耦合Lévy过程中的Moses,Noah和Joseph效应
Moses, Noah and Joseph Effects in Coupled Lévy Processes
摘要:
我们研究了一种方法,用于检测异常扩散的起源,当它被观察到在一个合奏的时间序列,实验或数值生成的,没有知识的确切的基本动力学。均方位移的异常扩散标度的原因被分解为三个根本原因:增量相关性由“约瑟夫效应”表示[Mandelbrot 1968],增量概率密度的厚尾导致“诺亚效应”[Mandelbrot 1968],非平稳性导致“摩西效应”[Chen et al. 2017]。在适当的重新缩放后,基于这些效应的量化,增量分布在增加的时间收敛到时不变的渐近形状。对于不同的过程,这个渐近极限可以是一个平衡态,一个无穷不变的,或一个无穷协变的密度。我们使用时间序列分析的数值方法来量化一个非线性耦合的Lévy行走模型中的三个影响,比较我们的结果与理论预测,并讨论了该方法的一般性。
英文摘要:
We study a method for detecting the origins of anomalous diffusion, when it is observed in an ensemble of times-series, generated experimentally or numerically, without having knowledge about the exact underlying dynamics. The reasons for anomalous diffusive scaling of the mean-squared displacement are decomposed into three root causes: increment correlations are expressed by the "Joseph effect" [Mandelbrot 1968], fat-tails of the increment probability density lead to a "Noah effect" [Mandelbrot 1968], and non-stationarity, to the "Moses effect" [Chen et al. 2017]. After appropriate rescaling, based on the quantification of these effects, the increment distribution converges at increasing times to a time-invariant asymptotic shape. For different processes, this asymptotic limit can be an equilibrium state, an infinite-invariant, or an infinite-covariant density. We use numerical methods of time-series analysis to quantify the three effects in a model of a non-linearly coupled Lévy walk, compare our results to theoretical predictions, and discuss the generality of the method.
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