arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0711.0682cond-mat.stat-mechcond-mat.dis-nn
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复杂标度不变介质中的首次穿越时间

First-passage times in complex scale-invariant media

S. Condamin, O. Benichou, V. Tejedor, R. Voituriez, J. Klafter

摘要:

一个随机步行者到达一个给定的目标点需要多长时间?这个量,被称为首次通过时间(FPT),在过去的十年中导致了越来越多的理论研究。FPT的重要性源于第一次相遇属性在各种实际情况中所起的关键作用,包括无序介质中的传输,神经元放电动力学,疾病传播或目标搜索过程。大多数方法来确定的FPT属性限制域已被限制到有效的1D几何形状,或空间尺寸大于1只均匀介质1。在这里,我们提出了一个通用的理论,它允许一个准确地评估复杂介质中的平均FPT(MFPT)。值得注意的是,这种分析方法提供了一个通用的缩放依赖的MFPT的体积的限制域和源-目标的距离。这种分析是适用于广泛的随机过程,其特征在于长度标度不变的属性。我们的理论预测证实了无序介质,分形,异常扩散和无标度网络的几个象征性的模型的数值模拟。

英文摘要:

How long does it take a random walker to reach a given target point? This quantity, known as a first passage time (FPT), has led to a growing number of theoretical investigations over the last decade1. The importance of FPTs originates from the crucial role played by first encounter properties in various real situations, including transport in disordered media, neuron firing dynamics, spreading of diseases or target search processes. Most methods to determine the FPT properties in confining domains have been limited to effective 1D geometries, or for space dimensions larger than one only to homogeneous media1. Here we propose a general theory which allows one to accurately evaluate the mean FPT (MFPT) in complex media. Remarkably, this analytical approach provides a universal scaling dependence of the MFPT on both the volume of the confining domain and the source-target distance. This analysis is applicable to a broad range of stochastic processes characterized by length scale invariant properties. Our theoretical predictions are confirmed by numerical simulations for several emblematic models of disordered media, fractals, anomalous diffusion and scale free networks.

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