基于分形维数的交通流效率判别技术研究

Identification of Traffic Flow Efficiency Based on Fractal Dimension

复杂性和效率均是反映空管系统运行效能的关键特性,掌握两者之间的量变关系,有助于进一步揭示空中交通流的基本属性,提升空中交通的运行效率。基于分形理论,利用离散傅里叶变换计算了航路点系统交通流量时间序列的分形维数,判别交通流的复杂性。然后,选取延误和流容比作为表征交通流运行效率的特征指标。最后通过仿真实验分析了交通流复杂性和效率之间的量变关系。分析结果表明分形维数和延误、流容比均为正相关,变化速率与加权间隔期望呈负相关:分形维数和延误满足分段对数变化关系,和流容比间局部线性关系显著。根据航路点交通流复杂性和运行效率之间的变化关系,采取相应的流量管理策略,通过有效控制复杂性,提升航路运行效率。

Both complexity and efficiency are key characteristics which reflect the operation performance of the air traffic control system. Grasping their quantitative relationship can help further reveal the basic attributes of air traffic flow and improve the operation efficiency of air traffic. Based on the fractal theory,the Discrete Fourier Transform（ DFT） was adopted to calculate the fractal dimension of traffic flow time series of route-point system to identify the complexity of traffic flow. Then it selects delay and flow capacity ratio as characteristic indicators of traffic flow efficiency. Finally,it uses a simulation to help analyze the quantitative relationship between complexity and efficiency of traffic flow. Results show that delay and flow capacity ratio are positively related to the fractal dimension,and rate of change of the above positive correlation is negatively related to its weighted interval expectations. Fractal dimension has a sectionalized logarithm relation with delay,and a significant local linear relation with flow capacity ratio. According to the relationship between complexity and operation efficiency of route-point traffic flow,can be taken appropriate air traffic flow management strategies to improve route operation efficiency through effectively controlling the complexity.