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交通流时间序列在不同时间尺度上具有不同的波动特征.为了分析交通流的突变特征,以一段实际的交通流量序列为研究对象进行实证研究.采用小波变换的方法求得交通流在不同尺度上的突变点,按照小波函数过零点数目将交通流的尺度划分为若干层次,并分析了交通流突变的层次性.计算表明:以突变点数目为测度时,在一定的尺度范围内,交通流在突变层次上的突变点数目满足自相似性特征.因此,交通流的突变在不同尺度上具有无标度性.
In order to analyze the abrupt change of traffic flow, an actual traffic flow sequence is taken as the research object to carry on the empirical research.Wavelet transform method is used to obtain the traffic flow at different scales According to the number of zero crossing of wavelet function, the scale of traffic flow is divided into several levels and the level of traffic flow mutation is analyzed. The calculation shows that when the number of sudden change points is taken as a measure, within a certain range of scale, traffic flow The number of mutation points at the mutation level satisfies the characteristics of self-similarity, so the abrupt change of traffic flow has scale-free at different scales.