The Research Of Quality Inspection Stations For Express Items Based On Markov Decision Process

With the development and maturity of the express industry, the compression of the delivery time is gradually approaching the limit. The consumers pay more attention to the quality of the express items. How to protect and improve the quality of express items has become an important issue for the express enterprises. However, due to the privacy policy of the express, express enterprises can only identify the state of internal items through the external packaging generally, and take statistical control after the event. It is difficult to guarantee the quality of the items timely and effectively. Previous studies mostly focus on the evaluation and improvement for the quality of the express service. The research on the quality control for the items within the delivery process is quite few. Delivery process and manufacturing process have some similarities. The states of the express items change dynamically. Therefore, this paper is applied the method of allocation of quality inspection stations from the manufacturing system. Consider the cost elements comprehensively, and explore the optimal setting for the quality inspection stations of the express items within the delivery process.First, a statistical analysis of the operating, overdue, lost and damaged problems is carried out through some collected express service quality problem data. The analysis result indicates that in order to ensure the internal items from being damaged, it is quite necessary to add the inspection and repair for the external packaging within the delivery process. Then, take part of the unidirectional express network as the research object, and establish a discrete time Markova decision process model with limited stage under the certain assumptions. The state set is determined via the states of both the external packaging and internal items. The decision set is whether or not setting the quality inspection station in some step. State transition probabilities family is a state transition probability matrix under the certain decision. Cost parameters include the inspection cost, the repackaging cost, the transportation cost, and the penalty cost caused by the physical damage of the internal item. Take the minimum total cost of the system as the goal, and find out the optimal setting for the quality inspection stations within the delivery process. Finally, the paper uses MATLAB software to program for solving the model with related data and output the results, including the optimal inspection sequence, the total cost of the system and the proportions of the states of the steps. It investigate additionally that under certain conditions, how the changes of the state transition probability, the number of inspection stations and penalty cost influence the saving cost of the system and the reduction of the physical damage of internal items.The overall results show that the reasonable settings of the inspection stations within the delivery process can not only achieve the goal to save the total cost of the system or increase little total cost of it under the some certain extreme conditions, but also improve the quality of express items effectively. Thus comprehensive express service level is improved in this way. The research of this paper provides express enterprises with a new attempt to solve the quality problem of the express items. It also makes an extension and innovation to the contents and methods of the existing research on express service quality.