European J. of Industrial Engineering (36 papers in press)

Regular Issues

• The impact of online sales in centralized and decentralized dual-channel supply chains  
  by Subrata Saha 
  Abstract: This paper studies a supply chain structure featuring two different types of distribution channels through which manufacturers sell products. The centralised and decentralised distribution channels considered in this study are affected by online sales outside the structured channels. In the centralised distribution channel, two retail stores located in geographically distinct markets are operated by a single owner. In the decentralised distribution channel, two retailers independently operate two retail stores. In the non-cooperative scenario, the manufacturer always prefers the decentralised distribution channel irrespective of whether an online channel is used. To achieve channel coordination, a revenue-sharing contract is applied, but it can be used to coordinate only the decentralised distribution system. Therefore, a modified revenue-sharing contract is proposed to coordinate the centralised distribution system. The analytical study reveals that without coordination among the channel members, the manufacturer always earns maximum profit in decentralised distribution systems. However, if the supply chain is coordinated, then the manufacturer receives more benefits from using the centralised distribution systems under certain conditions. Propositions are presented to describe the characteristics of distribution structures, and to provide meaningful management guidelines for coordinating them. Extensive numerical investigations are also presented.
  Keywords: Supply chain management; Dual-channel supply chain; Revenue sharing contract; Pricing strategy; Stackelberg.
  DOI: 10.1504/EJIE.2018.10011153
   
  
• Risk-Averse Joint Facility Location-Inventory Optimization for Green Closed-Loop Supply  
  by Guodong Yu, Pengcheng Dong, Ying Xu, Xiao Zhao 
  Abstract: This paper considers a joint facility location-inventory optimisation for green closed-loop supply chain network design under demand uncertainty. Under the uncoordinated inventory policy, we propose a chance-constrained risk-averse bi-objective 01 mixed-integer nonlinear stochastic programming to minimise the total expected cost and CO2 emissions. To solve the model, we first present an equivalent reformulation with a single objective based on distributionally robust optimisation. Then, we provide a linear reformulation with some valid inequalities. We also provide a greedy heuristic decomposition searching rule to solve the large-scale problem. We finally present a numerical analysis to show the performance of our methods. Results illustrate that the risk-averse joint model can effectively improve service capability and reliability than independent and risk-neutral location and inventory problems. We also recommend that the incompletely uncoordinated strategy for the joint optimisation can be more cost-effective and generate fewer workloads. Besides, the proposed algorithm achieves a more desirable performance than CPLEX for large-scale problems.
  Keywords: green closed-loop supply chain; facility location; inventory; risk-averse; chance constraint; distributionally robust optimisation.
  DOI: 10.1504/EJIE.2023.10046132
   
  
• A survey on network design problems: main variants and resolution approaches  
  by Imen Mejri, Safa Bhar Layeb, Farah Zeghal 
  Abstract: Over the last decades, network design problems (NDPs) have been one of the most investigated combinatorial optimisation problems that are still catching the interest of both practitioners and researchers. In fact, NDPs pose significant algorithmic challenges, as they are notoriously NP-hard, and arise in several applications, mainly in logistics, telecommunication, and production systems. Based on the literature published mainly between 1962 and 2021, this paper provides a comprehensive taxonomy of NDPs and also identifies the most investigated variants as well as their main fields of application. This taxonomy highlights the diversity as well as the assets of this core class of operations research problems. Moreover, the main mathematical formulations and solution methods are reported. Finally, directions for future research on NDPs are derived.
  Keywords: network design problems; NDPs; literature review; survey; combinatorial optimisation.
  DOI: 10.1504/EJIE.2022.10046171
   
  
• Compact MILP Models for Double Row Layout Problem with Pairwise Clearance  
  by Richard Alaimo, Churlzu Lim 
  Abstract: Double row layout problem (DRLP) seeks for an optimal arrangement of departments along both sides of a central corridor to minimise the total material flow cost. This study considers a variant of DRLP where pairwise minimum clearance requirements between departments are enforced when they are assigned to the same side. This problem accounts for additional interaction that exists between departments during the layout planning process. Two mixed-integer linear programming formulations are proposed with the motivation that using fewer binary variables compared to the existing formulation in the literature helps reduce the solution time. Noting the NP-hardness of the problem, symmetry-breaking constraints are investigated in an effort to further alleviate the computational burden. The efficacy of the proposed models is demonstrated via a computational study using a set of test problem instances. [Submitted: 9 February 2022; Accepted: 11 August 2023]
  Keywords: facility layout; double row layout problem; mixed-integer linear programming; combinatorial optimisation; clearance requirements.
  DOI: 10.1504/EJIE.2025.10060235
   
  
• Performance Analysis for A Dual-Crane Automated Storage and Retrieval System  
  by Letitia M. Pohl, Mahmut Tutam 
  Abstract: Automated storage and retrieval systems (AS/RSs) were first implemented in the 1960s and continue to be installed today, albeit with dramatically evolved technologies. When compared to more manual systems, an AS/RS has the potential to dramatically reduce labour costs, with increased productivity, higher storage density, better order and inventory accuracy, and improved product security. Despite the advantages and widespread implementations, the typical unit-load, single-crane AS/RS is still often characterised by high initial costs and limited maximum throughput. This paper proposes a new design that uses two cranes in one aisle, where the cranes operate cooperatively to increase throughput, thereby allowing a facility that is at capacity to be retrofitted without a complete equipment upgrade and without the need for a new facility. We model travel time of the two cranes and develop system throughput equations. Significant throughput improvement is possible with the new design over a comparable single-crane AS/RS. [Submitted: 12 September 2022; Accepted 17 July 2023]
  Keywords: unit-load warehouse; automated storage and retrieval systems; AS/RS; dual-crane; optimal buffer position; throughput models.
  DOI: 10.1504/EJIE.2025.10059498
   
  
• A multi-period inventory model with price, time and service level dependent demand under preservation technology investment  
  by Sudarshan Bardhan, Indrani Modak, Bibhas Chandra Giri 
  Abstract: Price and time are two important parameters having significant impact on market demand, especially for fashion items, newly launched electronic products, etc. After-sale service facility offered by the retailers is seen to boost demand while investing in preservation technology reduces product spoilage. All these issues are taken into consideration while developing a multi-period inventory model where market demand depends on all three of the above-mentioned factors. The replenishment cycles are all of equal length, but due to the time-dependent nature of demand, the stock-in (and consequently stock-out) periods in the cycles are allowed to vary. The policy of planned shortages followed by replenishment in each cycle is adopted and seen to be fruitful indeed. Learning effect in holding and ordering costs are taken into account. The effects of limited capital and warehousing space are investigated. Numerical examples are employed to demonstrate the developed model and gain managerial insights from it. [Submitted: 23 December 2022; Accepted: 3 August 2023]
  Keywords: price dependent demand; learning effect; preservation technology; service level; multi-period inventory model.
  DOI: 10.1504/EJIE.2025.10059500
   
  
• Optimum Design of an Efficient Variables Sampling System for Validating Process Yield with Six-Sigma Quality Requirement and Creation of a Cloud-Computing Tool  
  by Chien-Wei Wu, Ming-Hung Shu, Bi-Min Hsu, To-Cheng Wang 
  Abstract: Six Sigma quality levels have become well-known process yield targets in supply chain channels. To meet this high-yield requirement, the variables tightened-normal-tightened sampling system (VTSS) operates a dynamic rule-switching strategy between sampling plans, becoming a flexible and economical method for practitioners to verify products. Existing VTSSs based on the process yield index are only designed to adjust sample sizes in tightened and normal inspections. In this paper, a VTSS with alterable acceptance standards is developed. We derive the proposed VTSS's operating characteristic function and integrate it with the producer's and consumer's yield-and-risk requirements to construct an optimisation model for the determination of the optimal system design. After conducting a series of investigations into the performance between the proposed VTSS system with the existing VTSS system with alterable sample sizes, we concluded the proposed VTSS could reduce the average sample size by more than 50% and has a steeper operating characteristic shape, which indicates superior cost-efficiency and discriminative power. Moreover, we designed a cloud-computing tool to build an open-access platform to help practitioners implement our proposed VTSS easily and efficiently. Finally, the practicality and applicability of the proposed VTSS are illustrated through an industrial case. [Received 15 December 2022; Accepted 25 August 2023]
  Keywords: Six Sigma; process yield; lot sentencing; alterable acceptance standard ; tightened-normal-tightened sampling system.
  DOI: 10.1504/EJIE.2025.10059660
   
  
• Sensitivity comparison of control charts under MAD shift detector using the rank set sampling scheme  
  by Nadia Saeed, A. Bushawiesh 
  Abstract: In this article, the sensitivity comparison of the standard Shewhart S-control chart is done with the MAD-control chart under the rank set sampling (RSS) scheme. The median absolute deviation (MAD) from the sample median is considered a robust estimator for the outlier's detection relative to the sample standard deviation (SD). Extensive simulations are conducted to evaluate the control charts' performance using both estimators under the RSS scheme for different sample sizes. The values for the out-of-control average run length (ARL1), standard deviation of run length (SDRL) and percentile points under different shifts are used as performance measures. On the basis of Monte Carlo simulations, it is revealed that as the shift gets large; control charts are equally effective to detect it while for small shifts, the suggested robust MAD-control chart performed well and better. A real-life dataset is analysed to support our findings from the simulation study for illustrative intents justified that the MAD robust estimator is a better outlier detector. [Submitted: 26 November 2022; Accepted: 11 August 2023]
  Keywords: rank set sampling; RSS; control chart; shift detector; outliers; median absolute deviation; MAD; percentile points; average run length; ARL.
  DOI: 10.1504/EJIE.2025.10060058
   
  
• An EPQ model with different demand and deterioration rate for two warehouses under shortage, learning and imperfect production.  
  by S. V. Singh Padiyar, Vandana Gupta, S.R. Singh, Naveen Bhagat 
  Abstract: This paper presents a mathematical framework to obtain a production model for deteriorating items with learning effect in production cost. The study considers different demand rates and different deterioration rate. In this model, one is own warehouse (OW) and other one is rented warehouse (RW) with different demand rate is considered. Every producer wants to get maximum benefit in his business, and he want to vacate the RW very soon, due to which he has to pay the least rent, so demand rate for RW is strictly increasing function of time. On the contrary, he can use his OW in such a way that the producer gets benefit and can build the selling price of inventory according to his profit, so demand rate for OW is selling price dependent. These assumptions effects on demand therefore production rate is taken as demand dependent. Shortage is also considered. Numerical example and sensitivity analysis of some parameters provided to examine the impact on the optimal total cost of the system. [Submitted: 28 January 2022; Accepted: 23 August 2023]
  Keywords: two warehouses; imperfect production; shortage; deterioration; learning effect.
  DOI: 10.1504/EJIE.2025.10060653
   
  
• A hybrid approach of genetic algorithm and truncated branch-and-bound for seru scheduling problem with sequence-dependent setup time  
  by Xiaohong Zhang, Zhe Zhang, Xiaoling Song, Xiaofang Zhong 
  Abstract: This paper concentrates on the seru scheduling problem considering sequence-dependent setup time to minimise the makespan, in which seru production system (SPS) is a new-type advanced manufacturing system to respond quickly to volatile market. A mixed-integer programming (MIP) model is formulated, and then a hybridisation of genetic algorithm with a truncated branch-and-bound method (GATBB) is designed to speed up the solving process. Truncated branch-and-bound (TBB) procedure is employed to find a better solution than the initial one given by the GA within a tighter upper bound. Computational experiments are carried out finally, and a series of results of experiments, analyses of variance (ANOVA), and Tukey test show that the GATBB algorithm significantly outperforms the GA and GA-PSO algorithm. Specifically, GATBB algorithm performs extremely well in finding high-quality solutions efficiently, and can find approximate and even exact solutions for instances with up to 100 products. [Submitted: 31 October 2022; Accepted: 25 September 2023]
  Keywords: seru production system; setup times; scheduling; genetic algorithm; branch-and-bound.
  DOI: 10.1504/EJIE.2025.10060760
   
  
• Applying a Modified Adaptive Large Neighborhood Search for Truck Scheduling and Pile Assignment in a Two-Stage Sorting System  
  by James C. Chen, Tzu-Li Chen, Yin-Yann Chen, Yung-Hsin Su 
  Abstract: In this study, we tackle the complexities of a two-stage semi-automatic sorting system, considering the diverse distribution requirements of parcels and the constraints imposed by sorting equipment. Our objective is to integrate two decision points the inbound truck schedule and the parcel sorting plan to minimise overall operational costs. We first formulate the problem using a mixed-integer linear programming model and then propose a mixed-coded modified adaptive large neighbourhood search (MCMALNS) algorithm to enhance performance. In our computational study, the proposed approach demonstrated the ability to quickly obtain high-quality solutions compared to other algorithms. Furthermore, a full factorial experiment was conducted to analyse cost variations across 36 scenarios. Factors including loading, deadline, arrival pattern, pile/commodity ratio, and algorithm were all identified as significant and exhibited considerable influence on the outcomes. The insights derived from this analysis provide valuable guidance for management personnel in decision-making. [Submitted: 30 January 2023; Accepted: 25 August 2023]
  Keywords: truck scheduling; two-stage sorting system; modified adaptive large neighbourhood search.
  DOI: 10.1504/EJIE.2025.10061219
   
  
• Pricing and Greening Strategies in a Dual-channel Supply Chain with Government tariffs and Cannibalisation under Demand Uncertainty  
  by Amit Ranjan, Anand Ranjan, J.K. Jha 
  Abstract: In light of the drastic exhaustion of natural resources and increased environmental pollution, to promote the use of green products, the government subsidises them and levies taxes on non-green ones. This paper considers a dual-channel supply chain with a manufacturer selling a green product online and a substitutable non-green product offline using a retail channel. The price differential splits the market into two segments. The stochastic linear demand is modelled as a function of prices, green quality level, and sales effort level, considering government tariffs and demand leakage. A centralised decision model is investigated for the case of uniform distribution and distribution-free demand. It is shown that the green quality level and the total supply chain profit increase with an increase in demand leakage. Also, it reveals that with an increment in government subsidy and tax, the total supply chain profit and green quality level are higher in uniform distribution. [Submitted: 20 April 2023; Accepted: 9 October 2023]
  Keywords: dual-channel supply chain; government tariffs; cannibalisation; uniform distribution; distribution-free.
  DOI: 10.1504/EJIE.2025.10061256
   
  
• Improving the Quality of Production through the Six Sigma Method in a Textile Business  
  by İzzettin Hakan Karaçizmeli 
  Abstract: This study aims to reduce seam mark defects to improve the quality in a cotton fabric manufacture business by using the Six Sigma method. The DMAIC steps were followed. First, potential root causes were identified through brainstorming. Causes related to sewing thread, sewing machine settings and operator mistakes came to the fore in the brainstorming. Then, a data collection plan was devised, and the necessary data were collected. The analysis of studies on root causes were conducted by using the collected data. It was found that sewing thread, one of the raw materials used, played a role in increasing the defects. Furthermore, it was found that sewing operators needed training, and the settings of the machines should be improved. For solving these problems, the improvements were put into use. Finally, necessary monitoring plans were made. The results of the study indicated that the seam mark defects were reduced by 63%. [Submitted: 23 May 2023; Accepted: 16 October 2023]
  Keywords: quality; textile; Six Sigma; process improvement; seam mark.
  DOI: 10.1504/EJIE.2025.10061430
   
  
• Shift scheduling and rostering with same shift-type and weekend-off fairness constraints in call centres  
  by Ruicheng Wang, Yue Xu, Xiuli Wang 
  Abstract: Based on the actual operational situation of call centres, this paper incorporates the constraints of the same shift-type within a week and the fairness of weekends-off into scheduling. Utilising the progressive decomposition structure of the same shift-type constraint, this paper constructs an integer programming model for multi-week scheduling optimisation problem of call centre agents. We first analyse the maximum lower bound of the problem and prove the optimality of its relaxation problem. Then we propose a two-stage algorithm which combines a constructive heuristic with neighbourhood search incorporating simulated annealing. Experimental results show that the integer programming model is only suitable for achieving optimal solutions for small-scale problems, while our two-stage algorithm can obtain (sub-)optimal solutions for large-scale problems. The impact of employment policy on labour costs is also discussed. [Submitted: 21 March 2023; Accepted: 12 November 2023]
  Keywords: call centre; shift scheduling; rostering; integer programming; optimal algorithm; heuristic algorithm; neighbourhood search; weekend-off fairness; same shift-type; operations management.
  DOI: 10.1504/EJIE.2025.10061821
   
  
• A Multi-Objectives Optimization Model for the Joint Design of Statistical Process Control and Engineering Process Control  
  by Salih Osman Duffuaa, Omar Dehwah, Abdul-Wahid Al-Saif, Anas Alghazi, Awsan Mohammed 
  Abstract: Statistical process control and engineering process control are two methodologies used for process control and improvement. These technologies have existed independently of one another. Consequently, this research aims to simultaneously design statistical process control and engineering process control utilising multi-objectives optimisation. In this research, statistical and economic criteria are used to construct statistical process control and engineering process control jointly. To solve the developed model, an effective heuristic method is proposed. A numerical example is used to illustrate the significance of combining the two techniques. The results showed that the proposed solution can obtain the Pareto efficient solutions. This will help decision-makers to select the best solution based on their preferences. In addition, the findings indicated that the expected income values range between $172.0839 and $177.2175, and the Taguchi cost values vary between $4.469333 and $7.907547. On the other hand, the power values range between 0.91373 and 1. Moreover, the results revealed that as the Taguchi cost increases the expected income will increase and the power will decrease. Furthermore, sensitivity analysis is performed to determine the effect of variables in the model. The sensitivity analysis showed that the power of the chart decreases as the value of sigma is raised. [Submitted: 31 July 2023; Accepted: 26 November 2023]
  Keywords: statistical process control; SPC; engineering process control; EPC; multi-objectives; control charts; process monitoring.
  DOI: 10.1504/EJIE.2025.10061955
   
  
• An Agile Optimization Algorithm for the Multi-Source Team Orienteering Problem  
  by Mattia Neroni, Javier Panadero Martinez, Elnaz Ghorbani, Majsa Ammouriova, Angel A. Juan 
  Abstract: In the team orienteering problem (TOP), a fixed fleet of vehicles have to collect rewards by visiting customers. Typically, all vehicles depart from a source depot and end in a sink depot. Also, each vehicle has a limited driving range, so not all customers can be visited. The goal is then to select the set of customers to be visited, and the corresponding routes to do it, such in a way that the total reward collected is maximised while respecting the aforementioned constraints. This paper explores a TOP variant with multiple source depots and where real-time solutions need to be provided, i.e., computation times need to be in the order of milliseconds even for mid-sized instances with hundreds of customers. To deal with this challenge, and taking into account that the problem is NP-hard, we propose an 'agile' optimisation algorithm that is based on a biased-randomised heuristic. Our approach can be applied in realistic and dynamic scenarios where vehicles need to recompute their routes in real-time, as vehicles are in-route, new customers appear, and some existing customers are not available anymore. [Submitted: 20 May 2022; Accepted: 31 December 2022]
  Keywords: agile optimisation; biased-randomised heuristics; team orienteering problem; TOP; dynamic scenarios.
  DOI: 10.1504/EJIE.2025.10062276
   
  
• Research on Pricing Strategy of Closed-loop Supply Chain Based on PIR and Recovery Effort  
  by Jun Yao, Dongyan Chen, Hui Yu 
  Abstract: Waste products bring opportunities and challenges to remanufacturing. A Stackelberg game model based on PIR and recycling effort is constructed to compare and analyse the optimal pricing, product demand and system benefits of the closed-loop supply chain with or without PIR and recycling efforts. The results are as follows: compared with the without of PIR and recycling effort, manufacturers can lower the retail price of their products under PIR and recycling efforts to promote the increase of product demand and system total revenue. When the PIR level and the cost saving per unit of remanufactured product are constant, the larger the recycling amount of waste products is, the more total cost will be saved. It can be seen that recycling efforts will indirectly affect the level of PIR. When the input cost coefficient of PIR meets certain conditions, the manufacturer can obtain the income brought by PIR. [Submitted: 14 December 2022; Accepted: 7 November 2023]
  Keywords: process innovation for remanufacturing (PIR); recovery efforts; closed-loop supply chain; Stackelberg game; pricing strategy.
  DOI: 10.1504/EJIE.2025.10062351
   
  
• Optimization of a Multi-Item Inventory model for deteriorating items with budget constraint, time-dependent holding costs, and two-level quantity discount: A comparison  
  by Mahdi Karimi, Seyed Jafar Sadjadi 
  Abstract: Considering the increasing number of perishable goods, it is necessary to study the inventory control of these items. Previously, due to the difficulty of the models and the need for solution methods, many fundamental assumptions were ignored. This article presents a multi-item economic order quantity model for deteriorating items. This paper's novelties are using dynamic programming, adding both budget and capacity constraints, and some realistic assumptions to the model. This study allows shortages with partial backlogging, and a two-level discount is available. Also, we investigated the unspent budget elsewhere to increase the total income. The greedy search and metaheuristic methods were used to compare the results with the primary method. The results show that the proposed dynamic programming can solve the problem and surpass metaheuristic methods in precision and running time (for small cases). A sensitivity analysis was conducted and resulted in some managerial and theoretical insights.
  Keywords: inventory control; economic order quantity; deteriorating items; budget constraint; capacity constraint; dynamic programming.
  DOI: 10.1504/EJIE.2025.10062773
   
  
• A mixed integer programming model and a hybrid VNS/TS algorithm for GVRP with the heterogeneous fleet, time windows, and vehicle selection  
  by Emine AKYOL ÖZER, Melis ALPASLAN TAKAN, Tugba Sarac 
  Abstract: The green vehicle routing problem (GVRP) is a logistical problem considering environmental effects. Existing GVRP studies considered important constraints such as time windows (TW) or heterogeneous fleets (HF), but mostly, they assumed that there is an available fleet where all vehicles can be used. However, some companies build their fleets using rented cars by selecting the vehicle numbers and types. Therefore, we focus on GVRP with the HF, TW, and vehicle selection to minimise travel, rental, and emission costs. A MIP model, and a hybrid algorithm combining variable neighbourhood search with the tabu search algorithm are proposed. The performance of the algorithm is demonstrated by using the modified Solomon test instances. The proposed algorithm could produce high-quality solutions within a short computation time. In addition, an average improvement of 45.49% and 16.69% are achieved respectively compared to the first scenario and the second scenario where the vehicles are held constant. [Submitted: 6 February 2023; Accepted: 9 January 2024]
  Keywords: heterogeneous fleet green vehicle routing problem; HFGVRP; green vehicle routing problem with time window; GVRPTW; vehicle selection; variable neighbourhood search; VNS; tabu search; TS.
  DOI: 10.1504/EJIE.2025.10063127
   
  
• Lagrangian-Based Solutions for the Multi-Level Production-Inventory Problem in Iron and Steel Production with Reverse Logistics  
  by Guoli Liu 
  Abstract: This research deals with the production-inventory problem originating from the ironmaking production system in Shanghai Baoshan Iron and Steel Complex. A mixed integer programming (MIP) model based on the minimisation of total related costs including production/purchasing costs, inventory costs and setup costs is proposed to determine the production and inventory quantities of all materials in each time period under material-balance and capacity constraints. To solve the problem, a decomposition approach based on Lagrangian relaxation (LR) is developed. A solution property is introduced to speed up the solving process. Heuristic strategies are applied to improve the upper bound. In order to further improve the quality of the solutions, an alternative Lagrangian relaxation algorithm based on variable splitting is derived. A detailed numerical evaluation based upon the actual production data from Baosteel is performed. The computational results reveal that the proposed algorithms can obtain good quality solutions within a reasonable time. [Submitted: 6 February 2023; Accepted: 25 February 2024]
  Keywords: combinatorial optimisation; Lagrangian relaxation; reverse logistics; production-inventory planning.
  DOI: 10.1504/EJIE.2025.10063416
   
  
• Measuring Modularity on Manufacturers' Distribution Channel Strategies: Direct selling, Reselling or Agency Selling  
  by Qinyu Song, Meng Yang, Yaodong Ni 
  Abstract: In recent years, consumers not only pursue cost-effective products but also begin to attach importance to individual customization. This paper investigates the effects of the modularity level on a manufacturer's three channel strategies. We find that the modularity level under reselling and agency selling is lower than that under direct selling. Considering modularity, the retail price under agency selling is lower than that under direct selling. Therefore, when the consumer pays attention to the modular design, if the commission fee is high (low), the manufacturer will adopt the direct selling (agency selling) model. However, when the consumer's customization concern is weak, the manufacturer prefers the reselling format. In addition, referring to dual distribution channels, the manufacturer may authorize the modular design to the retailer when the modular-sensitive the parameter is high. [Submitted: 29 August 2023; Accepted: 5 March 2024]
  Keywords: Distribution channel; Modularity; Agency selling; Reselling; Game theory.
  DOI: 10.1504/EJIE.2025.10064026
   
  
• Design and development of an optimization model and simheuristic framework for the on-demand delivery problem with driver-experience-based stochastic travel time  
  by Shuzhu Zhang, Bingbing Qiu, Jinyue Tian 
  Abstract: In this research, we investigate an on-demand delivery problem in city logistics, in which delivery requests from online customers are received in real-time and delivery services are conducted in short time. A multi-stage stochastic vehicle routing optimisation model is proposed, which incorporates two unique features arising from city logistics delivery, i.e., driver experience and stochastic travel time. In practice, the estimated travel time is indeed affected by the driver experience and can be gradually improved as drivers learn from accumulative delivery experience. A simheuristic framework is developed to handle the proposed model, in which an improved adaptive large neighbourhood search is designed for searching promising solutions with deterministic travel time, and Monte Carlo simulation is leveraged to assess the solution qualities and facilitate the searching process in stochastic scenarios. Computational experiments demonstrate that the proposed simheuristic framework can tackle the on-demand delivery problem with satisfactory performance. [Submitted: 22 November 2023; Accepted: 13 April 2024]
  Keywords: on-demand delivery; stochastic travel time; simheuristic framework; adaptive large neighbourhood search; driver experience.
  DOI: 10.1504/EJIE.2025.10064385
   
  
• A Sustainable Hub Location-Allocation Model considering the Inspection of Defective Wagons in the Rail Freight Network  
  by Bahareh Sohrabi Pirdousti, Amir Hossein Sheikh Azadi, Ali Heidari, Mohammad Khalilzadeh, Omid Kebriyaii 
  Abstract: The increasing demand for rail transport necessitates an effective transportation network design for the shipment of goods with minimum cost and time. Since the breakdown of wagons is a main delay factor in rail transportation, the maintenance and repairs of defective wagons becomes prominent. In this study, main stations are considered as hubs, and hubs are places where defective wagons are collected. For this purpose, a robust multi-objective mathematical model is proposed to minimise transportation costs considering customer demand. Also, the model seeks to minimise the total transportation time and emissions. The AEC method is exploited to solve and validate the proposed model. Moreover, the sensitivity analysis is performed to demonstrate the effect of changing the main parameters on the outcomes. The results show that repairs and maintenance can affect the capacity. Also, the findings demonstrate the applicability and validity of the proposed model in the railway sector. [Submitted: 29 May 2023; Accepted: 16 January 2024]
  Keywords: railway transportation; sustainability; hub location-allocation; maintenance; repair; augmented epsilon constraint; AEC.
  DOI: 10.1504/EJIE.2025.10064728
   
  
• Designing a Reverse Biomass Supply Chain Network under Uncertainty Conditions using Robust Programming and Lagrangian Relaxation Algorithm  
  by Alireza Hamidieh, Bahareh Akhgari Rik 
  Abstract: Researchers have studied solutions for reducing pollution and resource waste caused by increases in environmental pollution and resource waste. Moreover, increased productivity, reduced energy generation costs, decreased dependence on fossil fuels and use of biogas in supply chain networks have attracted interest from many industrialists. This research designed a biomass-based reverse supply chain network under conditions of uncertainty about capacity, demand and raw material quality that focused on increased profits and reduced biomass waste. For this purpose, a two-stage stochastic mixed-integer programming model was developed and robust optimisation was used to cope with the uncertainty about the parameters of quality, demand and capacity. In addition, a Lagrangian relaxation (LR) algorithm for simplification of the complicated constraints of the NP-hard problem was developed that could solve large-scale problems with a competitive convergence rate. [Received 6 July 2022; Accepted 4 December 2023]
  Keywords: biomass; Lagrangian relaxation; quality; robust; supply chain.
  DOI: 10.1504/EJIE.2025.10064788
   
  
• Designing an Enhanced Acceptance Sampling Strategy with the Process Loss Index  
  by Armin Darmawan, Chien-Wei Wu 
  Abstract: To reconcile the differences between loose and stringent models and address product specifications sensitive to target value variations, a process loss index Le was introduced. This index assesses process capability by incorporating the concept of the quality loss function. Some researchers have integrated this index into variables sampling plans. In particular, Repetitive Group Sampling Plans (RGSP) offer cost advantages over single sampling plans, but their infinite sampling nature might lead to inefficiencies. To address this, our study introduces a modified RGSP with an adjustable lot disposition mechanism based on the process loss index. We establish an optimisation model to minimise the anticipated number of sample items, considering quality and risk constraints. Performance is compared to conventional methods using metrics such as average sample number, operating characteristic curve, and average run length. Ultimately, a practical demonstration is provided through an example to illustrate and validate the feasibility of the proposed plan. [Submitted: 22 January 2024; Accepted: 17 May 2024]
  Keywords: acceptance sampling; average sample number; quality loss; quality assurance; operating characteristic function.
  DOI: 10.1504/EJIE.2025.10064829
   
  
• Assessment of equipment financial performance in overall equipment effectiveness metric for gauging manufacturing equipment criticality  
  by CHEN FUNG LIEW, Joshua Prakash, Kok Seng Ong 
  Abstract: This paper introduces equipment cost effectiveness, a metric for evaluating the financial performance of equipment in manufacturing. While overall equipment effectiveness is widely used to assess operational performance, its limited focus on financial aspects necessitates a more comprehensive approach. Equipment cost effectiveness addresses this limitation by quantifying the wastage of equipment acquisition cost and maintenance cost at any overall equipment effectiveness level. Real-world data from the medical device, tyre flap, and semiconductor industries validate equipment cost effectiveness through correlation analysis, revealing a negative relationship between overall equipment effectiveness and both equipment acquisition cost and maintenance cost. Equipment cost effectiveness provides a holistic evaluation of equipment, enabling better decision-making and cost optimisation. By bridging the gap between operational and financial evaluations, equipment cost effectiveness offers valuable insights for enhancing equipment efficiency and resource allocation in manufacturing operations. [Received: 22 April 2023; Accepted: 10 November 2023]
  Keywords: overall equipment effectiveness; OEE; equipment cost effectiveness; ECE; equipment acquisition cost; maintenance cost; improvement cost.
  
  
• Designing a cumulative sum control chart using generalised Conway-Maxwell-Poisson distribution for monitoring the count data  
  by Fakhar Mustafa, Rehan Ahmad Khan Sherwani, Muhammad Ali Raza 
  Abstract: This study proposes a multipurpose cumulative-sum control chart based on the generalised Conway-Maxwell Poisson (GCOMP) distribution and names it the GCUSUM control chart. The proposed control chart monitors dispersed count data considering tail behaviour. Further, the proposed chart can also monitor zero-inflated count data. The proposed chart's in-control and out-of-control performance analyses have been conducted using different run-length (RL) criteria. A comparative study has been presented to show the effectiveness of the proposed GCUSUM chart over established charts for monitoring distinctive features of the count data. It has been observed that the proposed control chart is efficient in monitoring the under- and over- dispersion in the count data while considering the tail behaviour. The GCUSUM chart also monitors the zero-inflated count data without utilising the zero-inflation property. Numerical and real-life examples also validate the effectiveness of the proposed control chart. [Received: 24 July 2022; Accepted: 25 April 2023]
  Keywords: control chart; SPC; under-dispersion; over-dispersion; zero-inflation; tail behaviour.
  DOI: 10.1504/EJIE.2024.10057052
   
  
• A hierarchical approach to schedule the two-machine flow shop problem with flexible periodic synchronised maintenance  
  by Nahla Chabbah Sekma, Hatem Hadda 
  Abstract: This paper tackles the makespan minimisation for the well-known two-machine flow shop problem with flexible periodic maintenance activities on both machines. The maintenance starting dates are to be decided along with the job's sequence. We adopt a hierarchical approach in which we first decide the job's sequence and then the maintenance starting dates. We identify a dominance rule and a polynomial case, and construct an enhancement procedure. We develop and test several variants of Tabu search and simulated annealing metaheuristics. We also propose an adaptation of the well-known NEH heuristic. The experimental study shows the superiority of one of the variants of simulated annealing and the efficiency of the dominance rule. [Received: 15 July 2022; Accepted: 8 May 2023]
  Keywords: flow shop scheduling; flexible maintenance; Tabu search; simulated annealing.
  DOI: 10.1504/EJIE.2024.10057224
   
  
• Robust supplier selection under uncertain costs and delivery delay times  
  by Cassiano da Silva Tavares, Pedro Munari, Moacir Godinho Filho 
  Abstract: We address the supplier selection problem under uncertainty, motivated by the current economic situation of global trade. The intense search among organisations for responsiveness in meeting market demands has directed efforts toward supply chain optimisation. Consequently, the decision regarding the best supplier choice has become vital for the success of organisations, requiring a high level of accuracy and assertiveness under complex and uncertain environments. To support decision-making in global sourcing environments, we propose a robust optimisation model that incorporates cost and time uncertainties that commonly arise in the context of worldwide raw materials supply. The model includes raw materials inventory management, preventing stockouts and violations of physical storage constraints, while considering deviations of the uncertain parameters. We analyse the behaviour of the proposed model using 324,000 scenarios generated by Monte Carlo simulations. The results show that the proposed model increases the level of robustness without significantly increasing the value of the objective function when uncertain costs and times attain their worst-case scenarios (highest deviation). On average, the objective function values increased only 3.58% in the worst case, considering 20 products, 40 periods, 60 suppliers, and an uncertainty level of 50%. [Received: 1 June 2022; Accepted: 10 May 2023]
  Keywords: supplier selection; uncertainty; inventory; VUCA; robust optimisation.
  DOI: 10.1504/EJIE.2024.10058218
   
  
• Pragmatic simultaneous scheduling of machines, AGVs, tool transporter and tools in a multi machine FMS using flower pollination algorithm  
  by N. Sivarami Reddy, D.V. Ramamurthy, K. Prahlada Rao, M. Padma Lalitha 
  Abstract: This paper deals with machines, automated guided vehicles (AGVs), tool transporter (TT) and tools simultaneous scheduling in multi-machine flexible manufacturing system considering parts and tools transfer times for makespan minimisation. Only one copy of every tool type is made available due to economic restrictions and the tools are stored in central tool magazine that shares with and serves for several machines. TT and AGVs carry tools and jobs between machines. This simultaneous scheduling problem is highly complex in nature as it involves allocating tools, AGVs and associated trip operations including the dead heading and loaded trip times of both AGVs and TT to job-operations, job operations sequencing on machines. This paper presents nonlinear mixed integer programming formulation to model this problem and flower pollination algorithm (FPA) is employed to solve it. The results have been tabulated, analysed and compared. An industrial problem in manufacturing company is used for verification. [Received: 18 October 2020; Accepted: 26 May 2023]
  Keywords: flexible manufacturing systems; automated guided vehicles; AGVs; scheduling of jobs; TT and tools; optimisation techniques; flower pollination algorithm; FPA; makespan.
  DOI: 10.1504/EJIE.2024.10059497
   
  
• The solution of bi-criteria flow shop scheduling problem through mathematical modelling and its application in a shoe factory  
  by Ayşe Çelik, Serkan Kaya 
  Abstract: This paper addresses a problem occurring in a real-life shoe manufacturing factory consisting of 28 machines. Due to a large number of orders, frequent and long delays in the delivery of the products to customers occur, which costs the factory a significant amount. The problem is formulated as a flow shop scheduling (FSS) problem and a 0-1 integer goal programming model is developed. Computational experiments indicate that problems with up to 50 jobs can be solved within a reasonable time by the developed model. A comparison of the results with the actual case in the factory revealed that, on the average, an improvement of 72.0% in total tardiness (TT) was achieved while an improvement of 3.9% was achieved in the maximum completion time. This helped to save the factory significantly. [Received: 30 January 2023; Accepted: 1 June 2023]
  Keywords: flow shop scheduling; FSS; 0-1 integer goal programming model; shoe manufacturing; makespan; total tardiness; TT.
  DOI: 10.1504/EJIE.2024.10057892
   
  
• A study on pricing and recycling strategies for retailers with consideration of selling new and refurbished products  
  by Yeu-Shiang Huang, Chih-Chiang Fang, Yi-Hsiang Tsao 
  Abstract: Used products can be recycled for remanufacturing, but refurbished products may still compete with new products in a market since some price-sensitive consumers may be attracted by a low price. Therefore, firms should make price decisions for new and refurbished products with caution. This study investigates a retailer's pricing and recycling strategies for two types of consumers: quality-oriented consumers and price-sensitive consumers. The work examines internal and external competition between new and refurbished products with the consideration of consumer heterogeneity. A Stackelberg game theoretic model will be considered in the study, in which the manufacturer is a leader, who determines the official price and wholesale price first, and the retailer is a follower, who then accordingly develops optimal pricing strategies considering the two recycling policies. The analytical results show that retailers would rather recycle products on their own than outsource recycling if they were more capable of remanufacturing. [Received: 24 June 2022; Accepted: 10 May 2023]
  Keywords: pricing; remanufacturing; consumer heterogeneity; game theory.
  DOI: 10.1504/EJIE.2024.10057620
   
  
• Hotel overbooking, capacity rationing and cooperation with third-parties: a two-period optimisation model  
  by Nazli Karataş Aygün, Önder Bulut 
  Abstract: We propose a two-period optimisation model for a hotel revenue management (RM) problem where overbooking, capacity rationing and cooperation with third-party websites are simultaneously considered. In a Stackelberg game structure, the hotel first sets the price, and overbooking and rationing levels, and as the followers, third-parties decide their effort levels by a Nash game. The proposed model is solved using a genetic algorithm. An extensive numerical study is performed to investigate the effects of multiple night stays, hotel effort level, and hotel capacity on the decisions and the hotel profit. It is shown that the value of capacity rationing increases with multiple night stays and the expected profit of the third-parties is decreasing with the hotel effort level but the relation between the hotel effort level and profit is not monotone. As the hotel capacity is expanded, the effort level of the third-parties and the hotel profit increase. [Received: 1 December 2021; Accepted: 26 May 2023]
  Keywords: pricing; overbooking; third-party websites; multiple night stays; multiple customer classes; two-period optimisation model.
  DOI: 10.1504/EJIE.2024.10058072
   
  
• Evaluating dispatching rules for make-to-availability under simplified drum-buffer-rope: a computational experiment  
  by Robson Flávio Castro, Roberto Fernandes Tavares Neto, Moacir Godinho Filho 
  Abstract: This research evaluates the impact of some dispatching rules (DR) on the performance of make-to-availability (MTA) under the simplified drum-buffer-rope (S-DBR) system. S-DBR/MTA seeks to ensure the availability of finished products to meet demand, so production needs to replenish inventory quickly. The DR has an important influence on the replenishment speed, which dictates the performance of such systems. We evaluate four rules found in the literature (FIFO, AT, SPT, and SRPT), two of the S-DBR/MTA (PSP and PSP1), and six rules combining the two groups (PSP-AT, PSP-SPT, PSP - PSP1-AT, PSP1-SPT, and PSP1-SRPT) using a computational experiment. We use the following measures to evaluate the performance of such rules: service level, average inventory in the system, mean flow time, and stock rate per service level percentage. The PSP1-SPT rule gets better results than others, increasing the S-DBR/MTA performance. [Received: 17 August 2022; Accepted: 4 June 2023]
  Keywords: make-to-availability; MTA; simplified drum-buffer-rope; S-DBR; theory of constraint; dispatching rule; DR; flow-shop; scheduling; work-in-process; WIP; finished goods inventory; FGI.
  DOI: 10.1504/EJIE.2024.10057827
   
  
• The influence of shelf life on the integrated production scheduling and vehicle routing optimisation for perishable products  
  by Hercules Tadeu Asato Dantas, Roberto Fernandes Tavares Neto, Juliana Keiko Sagawa 
  Abstract: Prior studies on integrating production and distribution optimisation highlight the benefits of such an approach. However, no studies regarding standardised metrics for categorising shelf life lengths in different scenarios were found. Moreover, the current literature does not address the change of behaviour on solving strategies accordingly to different shelf life profiles. To address these gaps, this research proposes the normalised shelf life metric to classify long and short shelf life products. Additionally, we present a simplified optimisation formulation for the integrated production scheduling and vehicle routing problem. By evaluating three solution methods (MILP model, genetic algorithm, and logic-based Benders decomposition model), our findings reveal that shelf life significantly affects solution performance. These results emphasise the need for research focused on solution methods tailored specifically for short shelf life products. [Received: 26 July 2022; Accepted: 7 June 2023]
  Keywords: shelf life; production-distribution integration; perishable products; genetic algorithm.
  DOI: 10.1504/EJIE.2024.10058090
   
  
• Multi-objective university rescheduling problem by fuzzy programming technique  
  by Sunil B. Bhoi, Jayesh M. Dhodiya 
  Abstract: This study presents multi-objective university rescheduling assignment problem (MOURAP), when some faculty members have been left the institute due to unavoidable circumstances, i.e., disruptions. This presented model executed in two phases. The first phase discusses and formulates the university course rescheduling problem and allocates unassigned courses to available faculty members based on the preferences for course of the faculty members, administrators and the indirect students preferences computed on faculty feedback and student result analysis. In the second phase, faculty members and courses are assigned to time in pairs, based on the faculty member's preferences. The prime aim of rescheduling is to minimise the course allocation change from former and latter to faculty members and time slots allocations change from initial and new schedule to faculty members and students. To test the strength of the presented model, this study demonstrated the model with two numerical examples on hypothetical data. With hypothetical numerical data, the model has been executed and has generated a new schedule by fuzzy programming technique with linear and exponential membership functions. This technique always produced non-dominated/compromise solutions. Results are obtained using LINGO19.0 software. [Received: 14 January 2022; Accepted: 9 July 2023]
  Keywords: university scheduling; rescheduling; 0-1 integer programming; fuzzy programming technique.
  DOI: 10.1504/EJIE.2024.10058383