Purpose The purpose of this paper is to develop a fuzzy analytic network process (FANP) model to select the maintenance policy of an acid manufacturing company. Design/methodology/approach Four maintenance strategies of Corrective Maintenance (CM), Time-Based Maintenance (TBM), Condition-Based Maintenance (CBM) and Shutdown Maintenance (SM) are investigated to be considered for seven equipment of the case study. These equipment are almost new and include boiler, molten sulfur ponds, cooling towers, absorption tower, converter, sulfur fuel furnace and heat exchanger. Chang’s extended analysis has been employed to deal with fuzzy data and analyze the fuzzy decision matrices. The proposed approach is applied to a sulfuric acid production plant and the suitable maintenance policy is found for all seven equipment of the company. Findings Based on the obtained results, the CBM policy is appropriate for high-risk (cooling tower) and high added value equipment (absorption tower). In addition, TBM is selected for boiler and converters while SM is selected for molten sulfur ponds. Finally, high-cost, low-risk and low added value equipment (sulfur fuel furnace and heat exchanger) are more appropriate with CM policy. Originality/value This research presents a novel idea to consider cost, risk and added value in the context of maintenance policy selection. From the methodological and theoretical features, this research offers new insights in this area since, to the best of the authors’ knowledge, no comparable study has been conducted before.

The present study reviews different studies on inventory control of deteriorating items in chain supply published over the period 1963-2013. The study investigates supply chain of the items in terms of various perspectives. Finally, the summary of the studies is shown in two tables for oneechelon and multi-echelon supply chain including the main information and assumptions of each paper. In the mentioned tables, the papers were classified in terms of the type of demand rate, deterioration rate, solution procedure and findings. It can be said that no analysis on the results was done in the present study and it can be only used as a good reference in the study field for other researchers.

The flexible job shop scheduling problem (FJSP) is an extension of the classical job shop scheduling problem (JSP) which allows an operation to be processed by any machine from a given set of machines. FJSP is NP-hard and presents two major difficulties. The first is to assign each operation to a machine out of a set of capable machines; and the second deals with sequencing the assigned operations on the machines. However, it is quite difficult to obtain an optimal solution to this problem in medium and large size problems with traditional optimization approaches. In this paper, a memetic algorithm (MA) for flexible job shop scheduling with overlapping operations is proposed that solves the FJSP to minimize makespan. We also proposed a heuristic that uses the critical path method (CPM) in order to improve the results of MA and reduce the objective function. The experimental results of MA and CPM show that our approach is capable of achieving the optimal solution for small size problems and near-optimal solutions for medium and large size problems in a reasonable time.

Nowadays enterprises should consider seeking to reduce the supply chain risks as a crucial part of their activities in order to improve their competitiveness in the international context. Choosing the suitable strategy in connection with assigning some parts of the production process to outside the organization is a complex multi-criteria decision making problem and it gets more complicated when supply chain risk factors as the factors to select the strategy as well as dependence and the close ties between these criteria also be considered. In this paper, after the identification of risks in the supply chain of a medical equipment manufacturer company, dependence and ties between criteria in line with choosing the best strategy among existing alternatives has been examined in the form of a combined ANP-ELECTRE method. This combined model has high performance to give a solution to the problem considered in this paper. Because of the complexity and time consuming nature of the AHP and ELECTRE, in this study a metaheuristic algorithm is developed called SIMANP that despite the simplicity of computing and high-speed, is good in the terms of precision and efficiency. The results of comparing SIMANP algorithm and the proposed ANP -ELECTRE method are presented at the end of the paper.Growing Science Ltd. All rights reserved. 7

This paper deals with part sequencing and optimal robot moves sequence in 2-machine robotic cells according to Petri net graph. We have assumed that the robotic cell is capable of producing same and different parts. We have considered a new motion cycle for robot moves sequence which is the development of existing motion cycles in 2-machine robotic cells. The main goal of this study is to minimize the cycle time by determining the optimal part sequencing and robot moves sequence in the robotic cell. So, we have proposed a model based on Petri network