S. Cheybani | Searcharxiv

arXiv2000

Stochastic boundary conditions in the deterministic Nagel-Schreckenberg traffic model

We consider open systems where cars move according to the deterministic Nagel-Schreckenberg rules and with maximum velocity ${v}_{max} > 1$, what is an extension of the Asymmetric Exclusion Process (ASEP). It turns out that the behaviour of the system is dominated by two features: a) the competition between the left and the right boundary b) the development of so-called "buffers" due to the hindrance an injected car feels from the front car at the beginning of the system. As a consequence, there is a first-order phase transition between the free flow and the congested phase accompanied by the collapse of the buffers and the phase diagram essentially differs from that of ${v}_{max} = 1$ (ASEP).

cond-mat.stat-mech↗

arXiv2000

The nondeterministic Nagel-Schreckenberg traffic model with open boundary conditions

We study the phases of the Nagel-Schreckenberg traffic model with open boundary conditions as a function of the randomization probability p > 0 and the maximum velocity ${v}_{max} > 1$. Due to the existence of "buffer sites" which enhance the free flow region, the behaviour is much richer than that of the related asymmetric exclusion process (ASEP, {v}_{max} = 1$). Such sites exist for ${v}_{max} \ge 3$ and p < ${p}_{c}$ where the phase diagram is qualitatively similar to the p = 0 case: there is a free flow and a jamming phase separated by a line of first-order phase transitions. For p > ${p}_{c}$ an additional maximum current phase occurs like for the ASEP. The density profile decays in the maximum current phase algebraically with an exponent $γ\approx 2/3$ for all ${v}_{max} \ge 2$ indicating that these models belong to another universality class than the ASEP where $γ= 1/2$.

cond-mat.stat-mech↗