Journal of Quality Engineering and Management

Abstract  The present paper focuses on the utilization of simulation approach for modelling the problem in the presence of different factors of uncertainty, as well as response surface methodology on the simulation results in sequencing problem of a 3-machine robotic manufacturing cell under S6 cycle, where produces multiple parts. The process supports by a single gripper robot to load/unload products and also displacement within the system. This study considers machine’s failure and repair such that machine’s probability density function of failure and repair time in this robotic cell follows exponential distribution. Minimizing both S6 cycle time and operational cost and maximizing throughput in this cell are the optimization’s main objectives. The simulation results of numerical examples indicate that this approach improves significantly the time of obtaining the optimal solution in comparison with the previous mathematical modelling.   

Abstract The reliability assessment of multi-state systems is often investigated by assuming the independence of the components. It is very useful to consider the interactions between components to evaluate the reliability of such systems. The traditional block diagrams do not evaluate the reliability of a repairable multi-state system. The use of simple stochastic process methods is very difficult due to the high dimension of the problem (the very large number of system states) for engineering applications. To the best of our knowledge, the universal generating function has not been used for systems with dependent components. In this paper, using stochastic processes and a universal generating function method, multi-system systems are analyzed in a situation in which the performance distributions of some components depend on the state of others.

Abstract This paper examines the issue of reliability and multi-objective redundancy allocation for series-parallel multi-state systems. Therefore, a suitable mathematical model is proposed in order to maximize the accessibility of the system and minimize the relevant design costs by considering the budget constraints and the physical weight of the system. In order to estimate the accessibility of a multi-state system, the general generator function method has been used, which is an efficient method for calculating the reliability and accessibility of multi-state systems. After solving the mathematical model by the Epsilon constraint method, in order to simultaneously optimize the two objective functions and generate partial solutions of the mathematical model of the problem on a larger scale, the second version of the genetic metaheuristic algorithm with unfavorable sorting has been developed. Finally, to evaluate the performance of the proposed solution algorithm, a number of sample problems in different dimensions have been generated and solved. The results of the meta-heuristic algorithm are compared with the results obtained from solving the mathematical model by the Epsilon constraint method by t-test, which indicates the efficiency of the proposed solution algorithm.