中国交通流的衰减函数模拟及特征

Function Simulation and Regularity of Distance Decay of Inter-Urban Traffic Flow in China

交通流具有随距离延伸而不断衰减的空间属性,距离衰减规律是交通地理学的重要议题。基于空间"流"距离衰减研究进展的评述,本文构筑了交通流距离衰减规律的主要可能函数模型,包括指数模型、Pareto模型、常对数模型、平方指数模型、开方指数模型,采用中国城际交通流包括公路客流、铁路客流、铁路货流和航空客流,分别对5种距离衰减模型进行了模拟并对比分析,从中识别出最佳的距离衰减函数是Pareto模型。然后,重点分析了各种交通流距离衰减函数的参数差异和地理内涵,并采用时间序列的交通流进行模拟,考察距离衰减函数的主要参数变化,并解释其地理内涵,同时绘制了交通流累计率曲线和分配率曲线,对各种交通方式的距离衰减函数模型、主要函数参数和距离衰减规律进行论证和解释。

Distance is always an important parameter of spatial interaction models in geography and influences the range and depth of many social and economic activities.There is a close and important linkage between traffic flow and distance.So the regularity of distance decay of traffic flow becomes the important research field of transportation geography and economic geography.Based on the review and comment on research progress of distance decay regularity of traffic flow in foreign countries and China,we narrated the studying data and city specimens applied in this paper,and introduced the primary modals of distance decay function,including exponent model,Pareto model,logarithm model,square exponent model and extraction exponent model.Then we simulated the five distance decay model applying inter-urban traffic flow in China,including road passengers flow,railway passengers flow and railway cargo flow,and aviation passengers flow.We discussed the several parameters of their simulating results including distance decay coefficient b,correlation coefficient R and test parameters（namely F and T）,especially provided a comparative analysis.According to the analytical result and simulating parameter,we chose the optimal function model of distance decay of traffic flow,namely,Pareto model,and wrote the specific function formulations of the four traffic flow modals.So we further analyzed the parameter difference of four distance decay models and their geographical implication,especially the relation between distance decay coefficient b and the application distance of four traffic flow modals,and their changes about distance decay parameter of temporal inter-urban railway passengers and cargoes flow and their spatial explanation.To provide a further explanation,it is necessary to do so through analyzing the traffic flows and related socialeconomic index.So we protracted the accumulative ratio curves and distribution ratio curves of four traffic flows,and demonstrated the distance decay model of traffic flow,their parameter and decay regularity which provided an experiential discussion.