Perimeter traffic control strategy based on macroscopic fundamental diagrams

A perimeter traffic signal control strategy is proposed based on the macroscopic fundamental diagram theory(MFD)to solve the signal control problem in oversaturated states.First,the MFD of a specific regional network can be derived using VSS IM simulation software.Secondly,the maximum number of cumulative vehicles that the network can accommodate is determined based on the MFD.Then,through monitoring the influx flow,the number of vehicles existing in and exiting from the network,a perimeter traffic control model is proposed to optimize the signal timing of the boundary intersections.Finally,a virtual network simulation model is established and three different kinds o f traffic demand are loaded into the network.Simulation results show that a fer the strategy implementation,the number o f vehicles accumulating in the network can be kept near the optimal value,while the number o f both entering and exiting vehicles increases significantly and the road network can be maintained at a large capacity.Simultaneously,the queue length at the approach of the border intersections is reasonably controlled and vehicles entering and exiting the network can maintain a more efficient and stable speed.The network performance indices such as the average traffic delay and average number of stops can be improved to a certain degree,thus verifying the effectiveness and feasibility of the perimeter control strategy.

底铰摆式波能装置在斜向波中的水动力性能

采用特征函数展开和二维格林函数相结合的方法求解底铰等厚度摆式波能转换装置水动力系数及斜向规则波作用下的波浪扰动力矩。二维积分方程中奇异积分项采用复变函数解析法求解,因此同时适用于有限厚度及薄壁底铰摆板的水动力计算。通过与文献及与AQWA软件水动力计算结果的比较,验证程序的正确性。类似于船舶横摇运动,在固有周期附近粘性阻尼对摆式波能转换装置的性能有很大影响。通过在运动方程中添加粘性阻尼项考虑粘性阻尼的作用,并在此基础上给出最佳负载阻尼系数的估算公式,分析波向角和波高对装置最佳转换效率的影响。