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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Journal of Industrial and Systems Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: particle swarm optimization,Variable neighborhood search,Centralized appointment scheduling,distributed echocardiography network,Shift scheduling,Capacity allocation
- چکیده:
- چکیده انگلیسی: Appointment scheduling systems are applied in a broad variety of healthcare environments to reduce costs and increase quality of services. This study is concerned with the problem of appointment scheduling in a distributed multi-hospital network of echocardiography departments. In this paper, a centralized master schedule is presented to maximize profit margin through maximizing the number of performed echoes and minimizing overtime. Developing such a schedule requires handling shift scheduling and capacity allocation problems simultaneously. Based on real-world settings, a mixed integer linear programming model is proposed for the research problem. Since this model requires a large amount of time and memory to provide good solutions, and fails to find feasible solutions for most of the test problems, two metaheuristics are proposed with different approaches. The first one is combined variable neighborhood search with simulated annealing (VNS-SA) and the second one is hybrid particle swarm optimization (HPSO). Also two lower bounding techniques based on patients’ assignment ( ) and specialists’ assignment ( ) are presented. Then the efficiency of the proposed model and algorithms is evaluated using a set of practical-sized test problems. The results showed that VNS-SA is capable of providing high quality solutions in reasonable amount of time for all test problems and outperforms HPSO. Furthermore, the superiority of over and the lower bound provided by the mathematical model was shown from both the quality and computational time points of view. Finally, some managerial notes and suggestions for extension are presented.
- انتشار مقاله: 17-08-1398
- نویسندگان: Delaram Chaghazardy,Seyed Hessameddin Zegordi,Mohammad Sepehri,Hassan Aghajani
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Industrial and Systems Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: pricing,Supply Chain Management,Market Power,Nash vs. Stackelberg game,Service level
- چکیده:
- چکیده انگلیسی: This paper is considering the competition between two multi-echelon supply-chains on price and service under balance and imbalance of market power between the chains which are analyzing through Nash and Stackelberg game approach. The problem is categorized as the centralized or decentralized structure of each chain, which means a few different possible scenarios are developing based on the Nash and Stackelberg games. The aim of the paper is to investigate the simultaneous effect of the chains’ structure and market power on the decision variables. As a surprise result, we show that in the Stackelberg game, the chain will not always have the second-mover advantage. Furthermore, the results demonstrate that the leader''s presence in the market may have different impacts on the situation depending on the structure of the chains. Also, when the chains take their decisions sequentially, the service and the price jointly play a strategic role in earning profits.
- انتشار مقاله: 11-09-1397
- نویسندگان: Narges Khanlarzade,Seyed Hessameddin Zegordi,Isa Nakhai Kamalabadi,Majid Sheikhmohammady
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Industrial and Systems Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Tabu Search,mixed integer linear programming,work shifts,Simultaneous production planning and scheduling,hybrid flow shop
- چکیده:
- چکیده انگلیسی: Simultaneous production planning and scheduling has been identified as one of the most important factors that affect the efficient implementation of planning and scheduling operations for the production systems. In this paper, simultaneous production planning and scheduling is applied in a hybrid flow shop environment, which has numerous applications in real industrial settings. In this problem, it is assumed that each time period includes a number of discontinuous intervals called work shifts. A novel mixed integer linear programming model is formulated. Since this problem is NP-hard in the strong sense, a new heuristic algorithm is developed to construct a complete schedule from a solution matrix that is embedded in the proposed Tabu search. A number of test problems have been solved to compare the performance of the proposed method with the exact method. The results show that the proposed tabu search is an effective and efficient method for simultaneous production planning and scheduling in hybrid flow shop systems.
- انتشار مقاله: 05-09-1397
- نویسندگان: Iman Hassanzadeh Nodeh,Seyed Hessameddin Zegordi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Industrial and Systems Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Cross-docking,vehicle routing problem,time windows,Bi-objective mathematical model
- چکیده:
- چکیده انگلیسی: This study addresses the pickup and delivery problem for cross-docking strategy, in which shipments are allowed to be transferred from suppliers to retailers directly as well as through cross-docks. Usual models that investigate vehicle routing in cross-docking networks force all vehicles to stop at the cross-dock even if a shipment is about to a full truckload or the vehicle collects and delivers the same set of products. In order to eliminate unnecessary stops at the dock, and thus reduce transportation costs, the designed model tries to decide about the best approach to deliver orders to retailers in a tailored network. In such a system, two objectives are taken into account: minimization of the total transportation cost and minimization of the total earliness and tardiness of visiting retailers. In order to deal with this problem, three multi-objective algorithms are developed. An evolutionary algorithm based on multi objective imperialist competitive algorithm (MOICA) is proposed, and the associated results are compared with the results obtained by non-dominated sorting genetic algorithm (NSGA-II) and Pareto archived evolution strategy (PAES) in terms of some metrics. The computational results show the superiority of the proposed algorithm compared to other algorithms in some metrics.
- انتشار مقاله: 26-08-1395
- نویسندگان: Asefeh Hasani Goodarzi,Nasim Nahavandi,Seyed Hessameddin Zegordi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Industrial and Systems Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Train timetabling,Urban rail,uncertain demand, robust stochastic programming
- چکیده:
- چکیده انگلیسی: In the context of public transportation system, improving the service quality and robustness through minimizing the average passengers waiting time is a real challenge. This study provides robust stochastic programming models for train timetabling problem in urban rail transit systems. The objective is minimization of the weighted summation of the expected cost of passenger waiting time, its variance and the penalty function including the capacity violation due to overcrowding. In the proposed formulations, the dynamic and uncertain travel demand is represented by the scenario-based multi-period arrival rates of passenger. Two versions of the robust stochastic programming models are developed and a comparative analysis is conducted to testify the tractability of the models. The effectiveness of the proposed stochastic programming model was demonstrated through the application to Tehran underground urban railway. The outcomes show the reductions in expected passenger waiting time of 22%, and cost variance drop of 60% compared with the baseline plans using the proposed robust optimization approach.
- انتشار مقاله: 12-08-1394
- نویسندگان: Erfan Hassannayebi,Seyed Hessameddin Zegordi,Mohammad Reza Amin-Naseri,Masoud Yaghini
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Industrial and Systems Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: pricing,Cooperative advertising,Bi-level programming,Multi-product supply chain,Substitutable and perishable products,Market Power
- چکیده:
- چکیده انگلیسی: In this article the coordination of pricing and cooperative advertising decisions in one-manufacturer one-retailer decentralized supply chain with different market power for channel members is studied. The products are both perishable and substitutable. The problem is modeled as a nonlinear bi-level programming problem to consider both retailer and manufacturer decisions about prices and advertisement expenditure as well as the amount of retailer’s purchase. An Improved Particle Swarm Optimization through combining PSO by local search and diversification is proposed to solve the model. Finally, a numerical example is presented to analyze the effect of market scale. Also the role of the values of coefficient of price elasticity on decisions is studied via the numerical example. Numerical results indicate that to raise profit when the consumers are more price-sensitive, both the manufacturer and the retailer should decrease their prices and increase their advertising expenditure. In the larger market scale, the manufacturer and the retailer are even permitted to increase their prices to gain more profit.
- انتشار مقاله: 15-04-1394
- نویسندگان: Seyed Hessameddin Zegordi,Maryam Mokhlesian
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Industrial and Systems Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: pricing,Bi-level programming,Decentralized supply chain,Disruption risk,Simulated annealing and Tabu search
- چکیده:
- چکیده انگلیسی: Pricing is one of the major aspects of decision making in supply chain. In the previous works mostly a centralized environment is considered indicating the retailers cannot independently apply their decisions on the pricing strategy. Although in a two-echelon decentralized environment it may be possible that supply chain contributors have encountered with different market power situations which provide that some of them try to impose their interests in pricing and/or volume of the products. In such situations the leader-follower Stackelberg game or more specifically bi-level programming seems to be the best approach to overcome the problem. Furthermore, in this study we consider the impacts of disruption risk caused by foreign exchange uncertainty on pricing decisions in a multi-product two-echelon supply chain. Also it is assumed that the market is partitioned to domestic and international retailers with segmented market for each retailer. The purpose of this paper is to introduce decisions policy on the pricing such that the utility of both manufacturer and retailers is met. Since the proposed bi-level model is NP-hard, a simulated annealing method combining with Tabu search is proposed to solve the model. A numerical example is presented to investigate the effect of foreign exchange variation on the decision variables through different scenarios. The results from numerical example indicate that the international retailers are indifferent to the manufacture undergoes changes where the domestic retailers react to changes, dramatically.
- انتشار مقاله: 27-02-1394
- نویسندگان: Maryam Mokhlesian,Seyed Hessameddin Zegordi,Isa Nakhai Kamal Abadi,Amir Albadvi
- مشاهده