A stochastic model of randomly accelerated walkers for human mobility

作者：Gallotti Riccardo; Bazzani Armando; Rambaldi Sandro; Barthelemy Marc^*

来源：Nature Communications, 2016, 7(1): 12600.

DOI：10.1038/ncomms12600

Recent studies of human mobility largely focus on displacements patterns and power law fits of empirical long-tailed distributions of distances are usually associated to scale-free superdiffusive random walks called Levy flights. However, drawing conclusions about a complex system from a fit, without any further knowledge of the underlying dynamics, might lead to erroneous interpretations. Here we show, on the basis of a data set describing the trajectories of 780,000 private vehicles in Italy, that the Levy flight model cannot explain the behaviour of travel times and speeds. We therefore introduce a class of accelerated random walks, validated by empirical observations, where the velocity changes due to acceleration kicks at random times. Combining this mechanism with an exponentially decaying distribution of travel times leads to a short-tailed distribution of distances which could indeed be mistaken with a truncated power law. These results illustrate the limits of purely descriptive models and provide a mechanistic view of mobility.

• 出版日期2016-8
• 单位中国医学科学院北京协和医院; 中国地震局