Study On Pallet Allocation Optimization Over A Pallet Pool

Pallets move the world. Currently, there are three methods to manage pallets:transfer of ownership, pallet exchange, and pallet pooling. Particularly, pallet pooling is the most popular management methods among the three. Pallet pool construction is defined as one of the most important project of the nine key projects mentioned in the "Logistics Industry Restructuring and Revitalization Plan". Based on the detailed analysis of pallet pools, we focused on the problem of how to allocate pallets over a pallet pool (having the right number of pallets for the right customer in the right place at the right time.). This problem has always been a critical concern for poolers, such as CHEP, iGPS, PLUS, etc.First of all, the concept of Pallet Pool was defined and the conceptual model of Pallet Pool was established. An important conclusion was made through the analysis of the evolution mechanism of Pallet Pool using of Synergy theory, which is that it is very important to optimize the pallet allocation over a pallet pool to maximize the profit of the pallet pool. The third-party owned pallet pool, the third-party managed pallet pool, the cooperation pallet pool, and the private pallet pool are classified as "Professional Pallet Pool". Besides the four professional pallet pools, we proposed another kind of pallet pools named "Non-professional Pallet Pool (Loose Pallet Pool)" according to Chinese national conditions. The operational processes of every kind of pallet pools were refined, which made a foundation for the research on pallets allocation optimization over a pallet pool.Then, optimization models for pallet allocation over a professional pallet pool under deterministic conditions were established. In the models, pallet reposition and pallet recovery were distinguished as two different allocation processes and we tried to optimize the whole pallet allocation processes including purchase (or borrowing or leasing), distribution, reposition, and recovery using a model. Additionally, we considered two new parameters "in truckload quantities" and "damage rates" which have not been studied yet. The validity of the models was demonstrated through case studies. Through numerical analysis, it was found how the factors affect decision making, such as damage rates, loading and unloading capacity, transportation capacity, storage capacity, processing time and in truckload quantities. Moreover it was also found how about the relationship between different pallets’ types.Furthermore, optimization models for pallet allocation over a professional pallet pool under stochastic conditions were established. In the models, we considered stochastic storage capacity and stochastic loading and unloading capacity which have not been studied yet. The validity of the models was demonstrated through case studies. Through numerical analysis, it was found how the confidence level and unitary punishment cost affect the decision making. Moreover it was also found how about the relationship between different pallets’types.Moreover, optimization models for pallet allocation over a professional pallet pool under uncertain conditions were established. In the models, we considered many uncertain parameters, including uncertain transportation capacity, uncertain storage capacity, uncertain loading and unloading capacity, uncertain demand at supply customer, uncertain damage rates, etc., which have not been studied in recent research. The validity of the models was demonstrated through case studies. Through numerical analysis, it was found how the weight assigned to each scenario affects the decision making. Moreover it was also found how about the relationship between different pallets’types.Finally, optimization models for pallet allocation over a non-professional pallet pool were established. In the models, we considered customer selection and recovery time constraints which have not been studied yet. The validity of the models was demonstrated through case studies. Through numerical analysis, it was found how the unitary rental per unitary time and dwell time affect the decision making. Moreover it was also found how about the relationship between different pallets’types.Through analyzing of all optimize allocation schemes for professional pallet pools under all conditions, it could be concluded some basic principles for pallet allocation over a professional pallet pool as:"Pallets reposition should be in advance of pallets distribution; To reposition and distribute pallets between two close locations; To recover pallets as soon as possible, while do not purchase (or borrow or lease) pallets if it is not necessary". And some basic principles for pallet allocation over a non-professional pallet pool,"To distribute pallets between two close locations; To recover pallets as soon as possible; Getting profit is the point ", also were proposed based on the analysis of optimize allocation schemes for non-professional pallet pools.