Optimal Preventive Maintenance Policy with Consideration of Production Wait

In this paper, we consider the replacement of a single unit with catastrophic failure mode. Besides replaced at a preset time, the unit is also replaced at failure time or if it encounters a production wait and its age has reached a threshold. The joint preventive maintenance interval and threshold optimization problem are formulated with the objective of minimizing the expected cost per unit time in long run. A numerical example is presented to illustrate the applicability of the model.     

异质流网联车的不同换道集聚策略

为研究车联网环境下异质交通流的演变规律，首先，引入相对熵定量描述异质流的有序性，并分析有序性与智能网联车（connected and autonomous vehicle,CAV）市场渗透率、协同自适应巡航控制（cooperative adaptive cruise control,CACC）队列数之间的内在联系，推导得出智能网联车渗透率的增加及队列数的减少可以提升异质流的有序性；其次，提出了保守型集聚（conservative aggregation,CSA）、激进型集聚（radical aggregation,RDA）两种改进的智能网联车集聚换道策略，并通过元胞自动机仿真实验，从通行能力、相对熵和平均队列长度等方面比较了无集聚（no aggregation,NOA）、常规集聚（conventional aggregation,CVA）、CSA、RDA 4种换道策略的优劣；最后，在CSA换道策略中分析了不同最小队列规模限制对于通行能力的影响.研究结果表明：在双车道环境下，采取集聚换道策略能使智能网联车形成CACC队列，使异质流趋于“有序”，在20～95辆/km密度范围内提升通行能力；...