路网阻抗异质下时间依赖型应急配送决策优化

Optimization on Time-dependent Emergency Distribution Decision under Heterogeneous Road Network Impedance

灾后应急物资配送末端环节受道路梗阻、车辆同期到达拥塞等客观物理因素制约,影响待救援点最佳配送时间。对此,基于交通路网实时状态划分阻抗类型,对路网通行情况以及路网阻抗程度进行数学描述,分析路网阻抗异质下应急配送时间依赖性特征,并提出时间依赖性计算方法,构建基于MEET模型的配送车辆碳排放率估算函数。在此基础上,同时考虑路网阻抗异质性以及配送时间依赖性,建立路网阻抗异质下以配送时间、车辆使用数量以及碳排放量为优化目标的应急配送决策优化模型,设计考虑始发时间依赖性的自适应遗传算法对模型进行仿真求解分析。结果表明应急配送的时间消耗、车辆使用量、碳排放量与路网阻抗异质性及时间依赖下的始发时刻密切相关,具体表现为:首先,配送车辆的始发时间对执行该条配送线路是否会进入阻抗时间段以及该线路总阻抗时间与总耗时的占比产生影响;其次,路网的通行状况对配送车辆的通行速度产生影响,不同路网阻抗条件下的车辆通行时间各不相同;然后,在上述两个因素的共同作用下,执行完配送任务的总时间消耗、车辆的使用量以及碳排放量将会受到同步同频影响;最后,构建的模型和设计的自适应遗传算法能有效规避路网阻抗时间段,减少应急配送在途时间和碳排放,为“两碳”目标下待救援点在最佳时间窗口实现应急配送低碳化、绿色化提供可行的决策支持。

The terminal link of post-disaster emergency material distribution is restricted by objective physical factors such as road obstruction and congestion of vehicles arriving at the same time,which affect the optimal distribution time of the rescue point.The impedance types are divided based on the real-time state of the transportation network,and the traffic conditions and impedance degree of the network are described mathematically.The time-dependent characteristics of emergency distribution under heterogeneous network impedance are analyzed,the time-dependent calculation method is proposed,and the carbon emission rate estimation function of distribution vehicles based on MEET model is constructed.On this basis,considering the heterogeneity of network impedance and distribution time dependence at the same time,the emergency distribution decision optimization model is set up under the heterogeneous network impedance with optimization targets of delivery time,vehicle number and carbon emissions,and the adaptive genetic algorithm model is designed considering of starting time dependence for the simulation analysis.The result shows that the time consumption,vehicle usage and carbon emission of emergency distribution are closely related to the impedance heterogeneity of the road network and the time-dependent onset time.The specific manifestations are in embodied in(1)firstly,the departure time of distribution vehicles has an impact on whether the distribution line will enter the impedance period and the proportion of the total impedance time and total time consumption of the line;(2)secondly,the traffic condition of the road network affects the traffic speed of the distribution vehicles,and the traffic time of the vehicles under different road network impedance conditions is different;(3)then,under the joint action of the above 2 factors,the total time consumption,vehicle usage and carbon emission of the delivery task will be affected by the synchronization and same frequency;(4)finally,the constructed model and the designed adaptive genetic algorithm can effectively avoid the road network impedance time period,reduce the in-transit time and carbon emissions of emergency distribution,and provide feasible decision support for the rescue point to realize low-carbon and green emergency distribution in the best time window under the goal of“Carbon Neutral and Carbon Peak”.