Abstract: Based on the NS traffic model with open boundary conditions, the influence of the injected probability [α], the removed probability [β], the maximum velocity [Vmax] and the randomization probabilities [ρ] on the flow [J] is simulated. Then the phase diagrams are constructed due to the change of [J] in different regimes. Results show that [J] can be improved along with the increase of [Vmax] within a certain range. When [ρ] is smaller than the critical randomization probability [ρc], it will not affect [J]. When ρ exceeds [ρc], the bigger the [ρ] is, the more obvious reaction on [J] is. [Vmax] and [ρ] determinate the phase diagrams. When [ρ<ρc], the phase diagram only consists of the free flow regime and the jamming regime, and the two regimes are separated by a curve. When [ρ>ρc], the maximum current occurs and it will increase with the increase of [ρ].

Key words: cellular automaton, traffic flow, flow, phase diagram

摘要： 基于开放边界条件下元胞自动机交通流NS模型，模拟入口概率[α]、出口概率[β]、车辆最大速度[Vmax]以及随机慢化概率[ρ]对系统流量[J]的影响，根据不同流相中流量[J]的变化规律，建立NS模型的相图。结果表明，车辆最大速度在一定范围内的增加能提高系统流量，车辆的随机慢化概率在小于临界随机慢化概率[ρc]时，不会对系统流量造成影响，而超过[ρc]时，随机慢化概率越大，对系统流量的反作用越明显。[Vmax]和[ρ]决定系统相图。当[Vmax=5]，[ρ<ρc]时，系统相图只由自由流相和堵塞流相构成，自由流相和堵塞流相被一条曲线分开；[ρ>ρc]时，最大流相出现，最大流相区域随着[ρ]增大而增加。

关键词: 元胞自动机, 交通流, 流量, 相图