车头间距与高速公路交通流混沌

为了分析交通流混沌的转化机理，探讨了车头间距与高速公路交通流混沌的关系．提出了一种快速判别交通流混沌的最大李雅普诺夫指数改进算法，并用此改进算法和功率谱法研究了高速公路实测交通流的混沌问题，绘制了实测交通流的功率谱曲线．通过分析功率谱曲线，可以明显地观察到交通流频谱出现了噪声和宽峰的变化；用最大李雅普诺夫指数改进算法计算实测交通流的最大李雅普诺夫指数，结果表明，高速公路实测交通流中存在混沌现象．研究表明，车头间距的变化是交通流混沌现象产生的根本原因．

Relationship between Distance Headway and Chaos in Traffic Flow on Expressway

The relationship between distance headway and chaos in traffic flow on expressway was investigated in order to analyze the formation mechanism of chaos in traffic flow. An improved algorithm for largest Lyapunov exponent was put forward for rapid identification of chaos in traffic flow. The chaos in traffic flow on an expressway was investigated with the improved algorithm and the power spectrum method. The power spectrums of the time series of the traffic flow were illustrated. Through the analysis of the power spectrums of the distance headway, it is clear that there are the variations of noise and wide apices. The largest Lyapunov exponents of the time series of the traffic flow were computed and used to identify the chaos in the traffic flow on the expressway. The results prove that chaos exists in traffic flow on an expressway indeed. The research shows that the change in distance headway is the main factor causing chaos in traffic flow.