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arXiv 0912.4608cond-mat.stat-mechcond-mat.dis-nn
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双向双车道排斥过程中障碍物处的动力学

Dynamics at barriers in bidirectional two-lane exclusion processes

Róbert Juhász

摘要:

研究了双通道排斥过程,其中颗粒在两个通道中以相反的方向移动,并且能够改变通道。重点是稳态行为的情况下,一个积极的电流被约束到一个扩展的子系统(无论是由适当的边界条件或嵌入环境),在没有约束的情况下,电流将是负的。我们发现了两种性质不同的定态,并用跃迁率的形式给出了它们的条件。在第一种稳态下,一个局部的粒子群与位于子系统中的抗冲击形成,电流随子系统的扩展指数地消失。这种行为类似于单通道部分非对称简单排除过程,并且可以例如在通过使两个通道中的跳跃率不相等来诱导局部驱动时实现。在第二种类型的稳定状态中,其例如在局部驱动纯粹由车道变化率的偏差引起的情况下实现,并且其因此在单车道模型中没有对应物,离域的粒子簇形成,其作为整体执行扩散运动,并且因此,电流与子系统的延伸成反比地消失。该模型还研究了淬火无序的存在下,其中,在离域的情况下,唯象的考虑预测异常缓慢,对数衰减的电流与系统的大小与通常的幂律相反。

英文摘要:

A two-lane exclusion process is studied where particles move in the two lanes in opposite directions and are able to change lanes. The focus is on the steady state behavior in situations where a positive current is constrained to an extended subsystem (either by appropriate boundary conditions or by the embedding environment) where, in the absence of the constraint, the current would be negative. We have found two qualitatively different types of steady states and formulated the conditions of them in terms of the transition rates. In the first type of steady state, a localized cluster of particles forms with an anti-shock located in the subsystem and the current vanishes exponentially with the extension of the subsystem. This behavior is analogous to that of the one-lane partially asymmetric simple exclusion process, and can be realized e.g. when the local drive is induced by making the jump rates in two lanes unequal. In the second type of steady state, which is realized e.g. if the local drive is induced purely by the bias in the lane change rates, and which has thus no counterpart in the one-lane model, a delocalized cluster of particles forms which performs a diffusive motion as a whole and, as a consequence, the current vanishes inversely proportionally to the extension of the subsystem. The model is also studied in the presence of quenched disordered, where, in case of delocalization, phenomenological considerations predict anomalously slow, logarithmic decay of the current with the system size in contrast with the usual power-law.

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