Department of Industrial Engineering (1994 - Present)
industrial engineering & Management
, Tokyo Institue of Technology, Tokyo, Japan
Industrial Engineering & Systems
, Sharif University of Technology, Tehran, Iran
industrial engineering
Industrial Engineering, Isfahan University of Technology, Isfahan, Iran
S.H. Zegordi is a Professor of Industrial Engineering in the Faculty of Industrial Systems Engineering at Tarbiat Modares University, Iran. He received his Ph.D. from the Department of Industrial Engineering and Management at Tokyo Institute of Technology, Japan, in 1994. He holds an MSc in Industrial Engineering and Systems from Sharif University of Technology, Iran, and a BSc in Industrial Engineering from Isfahan University of Technology, Iran. His main areas of teaching and research interests include production planning and scheduling, multi-objective optimization problems, meta-heuristics, quality management, and productivity. He has published several articles in international conferences and academic journals, including European Journal of Operational Research, International Journal of Production Research, Journal of Operational Research Society of Japan, Computers Industrial Engineering, Transportation Research Part E, International Journal of Advanced Manufacturing Technology, Decision Support Systems, Scientia Iranica - International Journal of Science and Technology, and Amirkabir Journal of Science and Engineering.
Although subsidies have had significant impacts on the electric vehicle (EV) market share, many governments have planned to eliminate subsidies. There is a concern that unsubsidized EVs reduce the EV market share, significantly. However, purchasing an EV instead of a fuel vehicle (FV) might impose a lower total cost of ownership (TCO) on customers, depending on their vehicle usage. In this case, supply chains could optimize their decisions considering which vehicle is affordable for each customer class from the view of TCO. This study investigates optimal pricing and free periodic maintenance service (FPMS) decisions in a two-stage electric-and-fuel automotive supply chain, considering TCO to estimate vehicle market shares under customer cl
This paper presents a new bi-objective mathematical model to design a build-to-order supply chain (BTO-SC) network. In this paper, the demand of customers (dealers) is lead-time dependent and the time-sensitive parameter of the lead time is also dynamic and time-dependent. The objectives are to minimize the supply chain network cost and the number of lost demands, respectively. This paper integrates procurement, production and distribution problems to consider the trade-off between lead time, logistic cost, and the lost demands derived from lead time in the BTO-SC. Due to the NP-hard nature of the proposed model, a new hybrid meta-heuristic algorithm is presented. The proposed model is validated by GAMS software, and some test problems gene
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 f
Trends like globalization, shorter product life-cycles, and cost reduction strategies in the global business environment have exposed many supply chains to various risks. Disruptions are one of the supply chain risks that can interrupt product flow, delay customer deliveries, and reduce supply chain revenues considerably. Prior planning for disruptions could greatly alleviate these consequences. A method to cope with disruptions is to use product substitution in the case of a product shortage. In this research, the supply chain of a livestock-drug distribution company in Iran, facing demand disruptions, has been chosen as a case study. For this purpose, a multi-stage stochastic integer programming model is proposed and solved using a custom
This paper seeks to develop a reliable network of cross-docks by taking in to account disruption and reliability issues to hedge against heterogeneous risk of cross-docking failure. In real environments, applying a recovery policy can be a feasible strategy to handle disruptions. Hence, in this study, a recovery policy has been addressed in the form of reallocating suppliers to alternative cross-docks or altering the transportation strategy to move shipments. In addition to cross-dock location design, the optimum capacity of opened cross-docks will be determined considering the loads that will be served by each cross-docking center under regular and disruption conditions. A mixed integer nonlinear programming formulation is pre
During the years of imposed sanctions against Iran, Iran Khodro Company (IKCO) got into a hazardous situation due to CKD parts’ purchasing cost increment and emersion of new product variants in the competitive market. To examine such situation, this study examines a multi-period semi-centralized dual-channel supply chain where a common retailer (free market) and two manufacturers’(IKCO and Saipa as a major competitor) direct channels are confronted with reference price dependent and stochastic demand. The problem is analyzed under Stackelberg and cooperative games scenarios using heuristic algorithm and a League Championship algorithm respectively, as solution methods. Results obtained from solving the problem with IKCO data proves high
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 mark
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 sear
Uncertainty is one of the main parts of the project management environment that can strongly affect the project objectives and cause unpredictable delays. This study presents a multi-objective optimization approach for constructing resilient project schedules under resource constraints to cope with uncertain activity durations. In this paper, the concept of resilient project scheduling is defined to measure the ability of schedules to deal with duration disruption. Since the direct evaluation of resiliency is computationally complicated and time-consuming, a new surrogate resilience measure is introduced. The proposed resiliency criteria measure the floating of activities and the risks associated with the completion of the proj
In this paper, we considered the competition between two multi-echelon supply chains with identical structures on price under two market power structures. For this purpose, we developed two different scenarios. In the first scenario, both supply chains decided simultaneously (the Nash game). In the second scenario, due to the imbalance of power between the two supply chains, we adopted the Stackelberg game in the model. Price equilibrium is obviously obtained through the Game Theory. The paper investigated the effects of different relations between the market sizes of supply chains and the supply chain structures on price and profit along with the analysis of power in the market. Based on these assumptions, it was found that the supply chai
Sanctions imposed by the West led to a period of economic stagnation in Iran in recent years. Automobile industry is among the industries that suffered from substantial losses from the sanctions. These sanctions were originated generally due to uncompensated damages incurred to automobile manufacturing supply chain process. Iran Khodro Company (IKCO) had been prohibited from Peugeot Company of France; hence, IKCO supplied its parts and components requirements via an intermediate country like Turkey in sanctions periods. Saipa proceeded to purchase production lines of Chinese automobiles and launched producing this country's automobiles in order to respond to disruptions caused by the sanctions. These Chinese automobiles have been considered
In this paper, a mathematical programming model is presented for integrated problem of closed loop supply chain network design and supplier selection. The suppliers propose discount policy based on purchase amount and loyalty of buyers which are both taken from the elements of Recency, Frequency and Monetary (RFM) technique. In contrast to the existing closed-loop supply chain network design models which select suppliers based on unit price and quantity discount, the proposed model considers loyalty discount policy along with unit price and quantity discount policy as elements of RFM technique in selecting suppliers. The main objective of this paper which is formulated by a mixedinteger programming model is to minimize the total cost throug
In this paper, we have examined minimising the total completion times in a single-machine scheduling problem with non-identical job release dates. This problem is known to be strongly NP-hard. We have proposed an effective lower bound-based. Also, a near optimal heuristic has been presented that has an average gap of less than 0.077% from the optimum solution. Additionally, in 18% of the problem instances with up to 60 jobs, the upper bound value is equal to the lower bound value. Then we provide two dominance properties. Subsequently, the proposed lower bound, upper bound and dominance properties have been applied in the branch and bound method and have been tested in a wide range of instances. Computational experiments demonstrate the abi
Di erent categories of Iranian handmade carpet are produced each year. Due to resource limitation, it is so important for managers to allocate more resources to the most e cient categories. Therefore, the main purpose of this illustration is to consider most e cient types of carpet in production and sales stages. To do so, di erent categories of Iranian handmade carpet are considered as DMUs. This study utilizes network DEA for constructing a model to analyze total and partial e ciencies of Iranian Handmade Carpet Company (IHCC), simultaneously. IHCC consists of three main departments that are working jointly to maximize productivity of the rm; therefore, the case of IHCC is a multi-stage system with shared intermediate variables, extra inp
This paper considers an inventory-routing problem in a distribution network in which kanban is used as a means to implement just-in-time strategy. There are a set of part suppliers and cross-docks in this network, which provide parts for an assembly plant. A novel mixed integer non-linear programming formulation is developed for the problem in which the optimum number of kanbans is determined considering inventory and transportation cost. In the other word, this research aims at reducing the level of inventory and transportation cost in a kanban controlled supply chain system, in which the number of kanbans is to be determined optimally considering demand from suppliers and geographical distribution of them. A fleet of vehicles is applied t
The results of dynamic efficiency evaluation not only help managers to realize their business' position in competitive market, but also enable them to compare current company’s performance with previous periods and do strategic planning properly. For doing so, network data envelopment analysis is a logical approach. Hence, the main objective of this illustration is to measure dynamic efficiency by means of network data envelopment analysis technique. Although different approaches in network DEA are introduced recently, the need for a comprehensive methodology in this area is remained because of the defects of previous methodologies. Consequently, a novel approach based on multi-objective optimization is introduced in this paper in order t
Uncertainty and non-deterministic nature of the real world makes planning and scheduling in cross-docks a very complicated task for decision makers. These constant changes that happen all the time, often, lead to an increase in costs and/or a decrease in efficiency. Most of the uncertainty in cross-docks is caused by un-known truck arrival times. In this study we address the problem of scheduling incoming and outgoing trucks at a cross-dock facility, when vehicle arrival times are unknown, through a cost-stable scheduling strategy. Two meta-heuristics, MODE and NSGA-II, are used for solving the designed sample problems and are compared with a random search based genetic algorithm existing in the literature. Finally, performance of each algo
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
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