关键词: 应急医疗物资, 动态调度, 需求紧急度, NSGA-Ⅱ

Abstract: In recent years, major emergencies have occurred frequently all over the world. The scheduling of emergency medical supplies is the key link of emergency medical supplies support. There are some issues of the single-cycle multi-transportation mode emergency medical supplies scheduling model, such that the transportation network is not appropriate, constraints of transportation modes are not considered comprehensively, or dynamic changes of supply and demand are not considered, resulting in local redundancy and unfairness of scheduling.
Firstly, the multi-period dynamic scheduling model of emergency medical supplies under emergencies is established. According to the response characteristics of emergency medical supplies after the outbreak of emergencies, this thesis adopts the three-level transportation network, from supply point to distribution center and to demand point. It uses a variety of transport tools to transport jointly, considering capacity constraints for trucks and departure schedule constraints for trains and aircraft. It establishes a dynamic demand urgency indicator for demand points and calculate a dynamic demand urgency of demand points to correct their satisfaction rates. By dividing the period and aiming at the shortest scheduling time and the maximum sum of the satisfaction rate of the affected people, a model of emergency medical supplies is constructed with multi-supply point, multi-distribution center, multi-demand point and multi-period dynamic scheduling.
Secondly, an algorithm based on non-dominated sorting genetic algorithm-II (NSGA-II) is designed for solving the dynamic scheduling model of emergency medical supplies. For individual coding, the combination of string coding and natural number coding can intuitively show the entire scheduling scheme. For non-dominated sorting, it is difficult to consider all constraints in individual coding due to a large number of model constraints. The traditional non-dominated sorting method is improved, and the individuals who meet the demand of the constraints and those who do not are hierarchically divided according to the magnitude of individuals exceeding the constraints.
Finally, a case of multi-period dynamic scheduling of emergency medical supplies is studied. The designed case is solved by the NSGA-II algorithm. The results show that at the end of scheduling response of emergency medical supplies, the higher the demand urgency of demand point is, the more its satisfaction rate exceeds the minimum satisfaction one. With an increase in the satisfaction rate of demand point in the whole scheduling process, the final demand is satisfied, which verifies the validity and rationality of the model. At the same time, the genetic algorithm (GA) is used to compared with the NSGA-II algorithm. The results show that the scheduling scheme set solved by the NSGA-II algorithm dominates the scheduling scheme by the GA algorithm, reflecting the effectiveness and advantage of the NSGA-II algorithm.
The conclusions show that the model built in this paper can consider the constraints of different transportation modes, and materialize the idea that the higher the urgency of the demand point, the greater the value of its satisfaction rate exceeding its minimum satisfaction rate, which ensures the fairness of the distribution of emergency medical materials.

Key words: emergency medical supplies, dynamic scheduling, demand urgency, NSGA-Ⅱ