Optimization Of Spare Parts Inventories With Random Demand

Spare parts are articles that can help servicemen keep the normal operating conditions of equipments. Large-scale industrial enterprises usually own a great number of equipments and spare parts. Some spare parts that have a huge impact on the normal operation condition have a high unit price. If such spare parts are stockpiled, overstocking inventory would lead to higher cost of capital and inventory management costs. On the other hand, if such spare parts are under stocked, the equipments would not work properly with the shortage of spare parts when the replacement is needed. Therefore, the key to enhance the core competitiveness of enterprises is to focus on the scientific and efficient management of the storage of spare parts, achieving the reasonable quota of spare parts in the warehouse and minimizing inventory cost and system breakdown loss.On the basis of the relevant domestic and overseas papers on optimization of spare parts inventories, and based on the characteristics of spare parts in large-scale industrial enterprises, this thesis has proposed a model of spare parts inventories with random demand.After setting up the mathematical model, this thesis demonstrated the existence of the optimal solution in the spare parts inventories model by one dimensional and multidimensional analysis. Meanwhile, it listed the corresponding algorithms and the sub-algorithms to solve this mathematical model. This thesis operated an example about a certain type of professional spare parts in a certain power station by using the mathematical model and algorithms mentioned above. The result showed that the total cost of spare parts (including inventory cost and system breakdown loss) has been decreased by 15.09%, if the spare parts inventories have been optimized by this model. Thus the result verified that the spare parts inventories model and its algorithms are accurate, reasonable, and practical. This theory can also help industrious enterprises improve their standard of management.The innovations of this thesis are as follows: (1)The spare parts inventories model with random demand is well established and spare parts are put into two categories—professional parts and common parts. By mathematical reasoning, the result shows that we can regard the two types of spare parts as the same in this model.(2)Instead of the index of spare parts, it is more practical for industrial management to use the index of system breakdown loss, combined with spare parts inventory cost as the objective function model.(3)This thesis demonstrates the optimization of the model and designs the corresponding algorithms, which can help the practitioners get an accurate solution in both mathematical models and practical cases.