13 research outputs found
Mean Field Theory for Pedestrian Outflow through an Exit
An average pedestrian flow through an exit is one of the most important index
in evaluating pedestrian dynamics. In order to study the flow in detail, the
floor field model, which is a crowd model by using cellular automaton, is
extended by taking into account a realistic behavior of pedestrians around the
exit. The model is studied by both numerical simulations and cluster analysis
to obtain a theoretical expression of an average pedestrian flow through the
exit. It is found quantitatively that the effect of exit door width, a wall,
and pedestrian's mood of competition or cooperation significantly influence the
average flow. The results show that there is suitable width of the exit and
position according to pedestrian's mood.Comment: 9 pages, 16 figure
Introduction of Frictional and Turning Function for Pedestrian Outflow with an Obstacle
In this paper, two important factors which affect the pedestrian outflow at a
bottleneck significantly are studied in detail to analyze the effect of an
obstacle set up in front of an exit. One is a conflict at an exit when
pedestrians evacuate from a room. We use floor field model for simulating such
behavior, which is a well-studied pedestrian model using cellular automata. The
conflicts have been taken into account by the friction parameter. However, the
friction parameter so far is a constant and does not depend on the number of
the pedestrians conflicting at the same time. Thus, we have improved the
friction parameter by the frictional function, which is a function of the
number of the pedestrians involved in the conflict. Second, we have newly
introduced the cost of turning of pedestrians at the exit. Since pedestrians
have inertia, their walking speeds decrease when they turn, and the pedestrian
outflow decreases.
The validity of the extended model, which includes the frictional function
and the turning function, is verified by both a mean field theory and
experiments. In our experiments, the pedestrian flow increases when we put an
obstacle in front of an exit. The analytical results clearly explains the
mechanism of the effect of the obstacle, i.e., the obstacle blocks pedestrians
moving to the exit and decreases the average number of pedestrians involved in
the conflict. We have also found that an obstacle works more effectively when
we shift it from the center since pedestrians go through the exit with less
turning
A stochastic cellular automaton model for traffic flow with multiple metastable states
A new stochastic cellular automaton (CA) model of traffic flow, which
includes slow-to-start effects and a driver's perspective, is proposed by
extending the Burgers CA and the Nagel-Schreckenberg CA model. The flow-density
relation of this model shows multiple metastable branches near the transition
density from free to congested traffic, which form a wide scattering area in
the fundamental diagram. The stability of these branches and their velocity
distributions are explicitly studied by numerical simulations.Comment: 11 pages, 20 figures, submitted for publicatio
Bubble burst as jamming phase transition
Recently research on bubble and its burst attract much interest of
researchers in various field such as economics and physics. Economists have
been regarding bubble as a disorder in prices. However, this research strategy
has overlooked an importance of the volume of transactions. In this paper, we
have proposed a bubble burst model by focusing the transactions incorporating a
traffic model that represents spontaneous traffic jam. We find that the
phenomenon of bubble burst shares many similar properties with traffic jam
formation by comparing data taken from US housing market. Our result suggests
that the transaction could be a driving force of bursting phenomenon.Comment: 9 pages,12 figure
Exact solution and asymptotic behaviour of the asymmetric simple exclusion process on a ring
In this paper, we study an exact solution of the asymmetric simple exclusion
process on a periodic lattice of finite sites with two typical updates, i.e.,
random and parallel. Then, we find that the explicit formulas for the partition
function and the average velocity are expressed by the Gauss hypergeometric
function. In order to obtain these results, we effectively exploit the
recursion formula for the partition function for the zero-range process. The
zero-range process corresponds to the asymmetric simple exclusion process if
one chooses the relevant hop rates of particles, and the recursion gives the
partition function, in principle, for any finite system size. Moreover, we
reveal the asymptotic behaviour of the average velocity in the thermodynamic
limit, expanding the formula as a series in system size.Comment: 10 page
Systematic experimental investigation of the obstacle effect during non-competitive and extremely competitive evacuations
Although some experimental evidence showed that an obstacle placed in front of a door allows making people's evacuations faster, the efficacy of such a solution has been debated for over 15 years. Researchers are split between those who found the obstacle beneficial and those who could not find a significant difference without it. One of the reasons for the several conclusions lies in the variety of the experiments performed so far, both in terms of competitiveness among participants, geometrical configuration and number of participants. In this work, two unique datasets relative to evacuations with/without obstacle and comprising low and high competitiveness are analyzed using state-of-the-art definitions for crowd dynamics. In particular, the so-called congestion level is employed to measure the smoothness of collective motion. Results for extreme conditions show that, on the overall, the obstacle does not reduce density and congestion level and it could rather slightly increase it. From this perspective, the obstacle was found simply shifting the dangerous spots from the area in front of the exit to the regions between the obstacle and the wall. On the other side, it was however confirmed, that the obstacle can stabilize longitudinal crowd waves, thus reducing the risk of trampling, which could be as important (in terms of safety) as improving the evacuation time
Cluster formation and anomalous fundamental diagram in an ant trail model
A recently proposed stochastic cellular automaton model ({\it J. Phys. A 35,
L573 (2002)}), motivated by the motions of ants in a trail, is investigated in
detail in this paper. The flux of ants in this model is sensitive to the
probability of evaporation of pheromone, and the average speed of the ants
varies non-monotonically with their density. This remarkable property is
analyzed here using phenomenological and microscopic approximations thereby
elucidating the nature of the spatio-temporal organization of the ants. We find
that the observations can be understood by the formation of loose clusters,
i.e. space regions of enhanced, but not maximal, density.Comment: 11 pages, REVTEX, with 11 embedded EPS file
Dependence of the transportation time on the sequence in which particles with different hopping probabilities enter a lattice
Systematic experimental investigation of the obstacle effect during non-competitive and extremely competitive evacuations
Although some experimental evidence showed that an obstacle placed in front of a door allows making people's evacuations faster, the efficacy of such a solution has been debated for over 15 years. Researchers are split between those who found the obstacle beneficial and those who could not find a significant difference without it. One of the reasons for the several conclusions lies in the variety of the experiments performed so far, both in terms of competitiveness among participants, geometrical configuration and number of participants. In this work, two unique datasets relative to evacuations with/without obstacle and comprising low and high competitiveness are analyzed using state-of-the-art definitions for crowd dynamics. In particular, the so-called congestion level is employed to measure the smoothness of collective motion. Results for extreme conditions show that, on the overall, the obstacle does not reduce density and congestion level and it could rather slightly increase it. From this perspective, the obstacle was found simply shifting the dangerous spots from the area in front of the exit to the regions between the obstacle and the wall. On the other side, it was however confirmed, that the obstacle can stabilize longitudinal crowd waves, thus reducing the risk of trampling, which could be as important (in terms of safety) as improving the evacuation time