1,193 research outputs found
Continuous and first-order jamming transition in crossing pedestrian traffic flows
After reviewing the main results obtained within a model for the intersection
of two perpendicular flows of pedestrians, we present a new finding: the
changeover of the jamming transition from continuous to first order when the
size of the intersection area increases.Comment: 14 pages, 9 figure
Crossing pedestrian traffic flows,diagonal stripe pattern, and chevron effect
We study two perpendicular intersecting flows of pedestrians. The latter are
represented either by moving hard core particles of two types, eastbound
(\symbp) and northbound (\symbm), or by two density fields, \rhop_t(\brr)
and \rhom_t(\brr). Each flow takes place on a lattice strip of width so
that the intersection is an square. We investigate the spontaneous
formation, observed experimentally and in simulations, of a diagonal pattern of
stripes in which alternatingly one of the two particle types dominates. By a
linear stability analysis of the field equations we show how this pattern
formation comes about. We focus on the observation, reported recently, that the
striped pattern actually consists of chevrons rather than straight lines. We
demonstrate that this `chevron effect' occurs both in particle simulations with
various different update schemes and in field simulations. We quantify the
effect in terms of the chevron angle and determine its
dependency on the parameters governing the boundary conditions.Comment: 36 pages, 22 figure
Chaos properties and localization in Lorentz lattice gases
The thermodynamic formalism of Ruelle, Sinai, and Bowen, in which chaotic
properties of dynamical systems are expressed in terms of a free energy-type
function - called the topological pressure - is applied to a Lorentz Lattice
Gas, as typical for diffusive systems with static disorder. In the limit of
large system sizes, the mechanism and effects of localization on large clusters
of scatterers in the calculation of the topological pressure are elucidated and
supported by strong numerical evidence. Moreover it clarifies and illustrates a
previous theoretical analysis [Appert et al. J. Stat. Phys. 87,
chao-dyn/9607019] of this localization phenomenon.Comment: 32 pages, 19 Postscript figures, submitted to PR
Frozen shuffle update for an asymmetric exclusion process on a ring
We introduce a new rule of motion for a totally asymmetric exclusion process
(TASEP) representing pedestrian traffic on a lattice. Its characteristic
feature is that the positions of the pedestrians, modeled as hard-core
particles, are updated in a fixed predefined order, determined by a phase
attached to each of them. We investigate this model analytically and by Monte
Carlo simulation on a one-dimensional lattice with periodic boundary
conditions. At a critical value of the particle density a transition occurs
from a phase with `free flow' to one with `jammed flow'. We are able to
analytically predict the current-density diagram for the infinite system and to
find the scaling function that describes the finite size rounding at the
transition point.Comment: 16 page
Lattice gas with ``interaction potential''
We present an extension of a simple automaton model to incorporate non-local
interactions extending over a spatial range in lattice gases. {}From the
viewpoint of Statistical Mechanics, the lattice gas with interaction range may
serve as a prototype for non-ideal gas behavior. {}From the density
fluctuations correlation function, we obtain a quantity which is identified as
a potential of mean force. Equilibrium and transport properties are computed
theoretically and by numerical simulations to establish the validity of the
model at macroscopic scale.Comment: 12 pages LaTeX, figures available on demand ([email protected]
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