【作者】 张鹏；

【导师】 薛郁；

【作者基本信息】 广西大学 ， 理论物理， 2020， 硕士

【摘要】 随着城市交通的发展,人们面临交通带来的三大问题:汽车增加造成的交通拥堵;汽车尾气排放造成的空气污染;汽车增多带来能耗增加的问题。为了缓解汽车带来的能源压力问题,需要对不同道路、不同状态下的车辆油耗问题进行研究。因此本文研究了基于交通流微观模型的道路上坡和下坡的油耗问题、基于元胞自动机的Na Sch(Nagel-Schreckenberg)模型的混合交通流油耗问题和基于交通流宏观模型的上、下坡道路的交通拥堵问题。本文主要的研究工作如下:(1)考虑前后车速度差,提出车辆上下坡的交通流优化速度模型。通过线性稳定性分析得到稳定条件,通过数值模拟得到交通流油耗的时空演化图,研究结果表明前后车辆速度差强度(敏感系数)对交通流的油耗有一定的影响,速度差敏感系数越大,油耗的波动越平稳;上坡坡角对交通流油耗有影响,坡度越大交通流油耗越大;下坡坡角对交通流油耗有影响,坡度角越大交通流油耗越小。(2)基于交通流元胞自动机中的Na Sch模型,提出了混合交通流元胞自动机模型。通过混合比引入不同车长车辆组成的混合交通流,研究在周期性边界条件下单一车道交通流的平均油耗。最终模拟结果表明随着占有率的增加,车辆每一百公里的油耗也增加;不同运动状态的车辆耗油量不同,加速状态的车油耗最大,匀速次之,减速的最少;混合比越大每一百公里的油耗越大,车长越长每一百公里的油耗也越大;研究不同最大速度对交通流油耗影响时,在占有率较低的区域最大速度越大每一百公里的油耗越多,在占有率较大的区域,由于车辆的空间限制车辆达到最大速度,使得车辆每一百公里的油耗相同。(3)应用微观变量和宏观变量之间的转换关系,从考虑上下坡优化速度模型出发,并且考虑最近邻车辆的速度差对上坡和下坡的影响,导出了宏观交通流流体力学模型。通过线性稳定性分析,得到了该模型的稳定性条件;通过非线性分析,得出了中性稳定线附近密度波的Kd V(Korteweg-de Vries)方程及其解;利用有限差分迎风格式进行数值模拟,得到了上坡和下坡交通流演化的时空斑图。模拟结果表明当道路为上坡时不稳态区域随着坡度的增加而减小,向后传播的密度波则逐渐消失;当道路为下坡时,不稳态区域随着坡度的增加而增大,密度波快速向后传播。更多还原

【Abstract】 People are faced with three major problems brought by traffic: traffic congestion caused by the increase of cars;Air pollution caused by vehicle exhaust emissions;The increase in the number of cars leads to increased energy consumption with the development of urban traffic.it is necessary to study the fuel consumption of automobiles on the roads and under different conditions.Therefore,the fuel consumption of traffic flow on uphill and downhill roads based on the micro optimal velocity model is investigated in this paper.The Na Sch(Nagel-Schreckenberg)model of mixed traffic is used in fuel consumption,and the traffic congestion problem on uphill and downhill is studied from the micro to macro models.The main study of this paper is as follows:(1)The microscopic traffic model on uphill and downhill is presented with consideration of the influence of speed difference between front and rear vehicles.The stability conditions are obtained by linear stability analysis,and the time-space evolution diagram of fuel consumption is obtained by numerical simulation.The simulation results show that the speed difference coefficient has a certain influence on the fuel consumption of traffic flow.The greater the relative speed sensitivity coefficient is,the more stable the fuel consumption fluctuation will be.The upslope angle has influence on the fuel consumption of traffic flow.The greater the slope,the greater the fuel consumption of traffic flow.The lower slope Angle has influence on the fuel consumption of traffic flow,the higher the slope,the smaller the fuel consumption of traffic flow.(2)Based on the Na Sch model of traffic flow,a cellular automaton model of mixed traffic flow is proposed.The average fuel consumption on single-lane under periodic boundary condition is studied by introducing the mixing ratio defined by the proportion of long cars.The numerical simulations result show that the fuel consumption per 100 km increases with the increase of vehicle occupancy.The fuel consumption of vehicles in different motion states is different.The fuel consumption of vehicles in accelerating state is the largest,followed by uniform speed and the least deceleration.The greater the mixing ratio,the greater the fuel consumption per 100 kilometers,and the longer the car length,the greater the fuel consumption per 100 kilometers.In the area with a low occupancy rate,the maximum speed is higher and the fuel consumption per 100 kilometers is higher.In the area with a high occupancy rate,the fuel consumption per 100 kilometers is the same because the vehicle space limits the vehicle to reach the maximum speed.(3)An extended macro hydrodynamic model is derived from a microscopic car-following model considering forward looking and backward looking effect on the uphill and downhill by employing the transformation relation from microscopic variables to macroscopic ones.The stability condition of this traffic model is obtained by performing linear stability analysis.Nonlinear analysis derives the Kd V equation and yields its solution to the density wave near the neutral stability line.We make use of the upwind finite difference scheme for simulation.The spatiotemporal evolution patterns of traffic flow on the uphill and downhill are obtained.When the road is uphill,unstable region is shrunken with slope of the gradient increasing and backward-traveling density waves gradually decrease and even disappear.When the road is downhill,unstable region is extended and density waves propagate quickly backward to the whole road with slope of the gradient increasing.更多还原