The effect of mixture lengths of vehicles and braking on the traffic flow behavior in two-lane roadway

Using a numerical simulation, we study the effect of the mixture lengths of vehicles on a traffic flow in a two-lane roadway, for periodic boundaries in parallel dynamics. A deterministic cellular automaton which is an extended version of the one-dimensional asymmetric model is used to take into account the exchange of the vehicles between the two lanes. The variation of mean velocity and flow in a two-lane roadway versus the initial concentration C1, of vehicles in first lane, are studied for different values of the initial ratio f, between cars in lane 2 and vehicles in lane 1, and initial concentration n of trucks in lane 1. The presence of trucks has an important effect on phase transition between the maximal velocity phase and high density one. Indeed, the maximal current value decreases with increasing the concentration of trucks, and occurs at higher values of the initial density of vehicles in lane 1. The phase diagram (f,C1) established for different values of n. The maximal velocity phase increases by increasing the concentration of trucks in the circuit. Also, to approach more the reality, we have taken into account the human factor by introducing random rates. The random noises have a great effect on the results compared to those obtained in the deterministic case. Indeed, the current flow decreases and the first-order transition (LDP)-(HDP) is replaced by a second-order one in the presence of random noises

Monte Carlo study of a superlattice mixed spins under a crystal and external magnetic fields

In this paper, we study the effect of both an external and crystal magnetic fields for a superlattice with mixed spins (1/2, 1), using Monte Carlo simulations. The ground state phase diagrams, in the external magnetic field, coupling constant and the crystal magnetic field planes, were established.  The effect of increasing temperatures has also been established showing the behavior of the magnetizations and susceptibilities, for fixed crystal field values. In particular, the obtained results as well as in the ground state phase diagrams, as for non null temperature are obtained for fixed external magnetic and crystal field values. On the other hand, the effect of the temperature on the hysteresis loops is presented showing that the decreasing temperature effect is to increase the absolute values of the corresponding coercitif magnetic field

Multicritical Behaviours in One-Dimensional Traffic Flow

The effect of the on-ramp and off-ramp positions i1 and i2 , respectively, on the one dimensional-cellular automaton traffic flow behaviour, is investigated numerically. The on-ramp and off-ramp rates at  i1 and i2 are α0 and β0 , respectively. However, in the open boundary conditions, with injecting and extracting rates α and β and using parallel dynamics, several phases occur, depending on the position of i1 by respect to i2. Namely, low density phase (LDP), intermediate density phase (IDP), plateau current phase (PCP) and high density phase (HDP). Furthermore, critical, tricritical and multicritical behaviours take place in the ( i1 , α0 ) phase diagrams.The effect of the on-ramp and off-ramp positions i1 and i2 , respectively, on the one dimensional-cellular automaton traffic flow behaviour, is investigated numerically. The on-ramp and off-ramp rates at  i1 and i2 are α0 and β0 , respectively. However, in the open boundary conditions, with injecting and extracting rates α and β and using parallel dynamics, several phases occur, depending on the position of i1 by respect to i2. Namely, low density phase (LDP), intermediate density phase (IDP), plateau current phase (PCP) and high density phase (HDP). Furthermore, critical, tricritical and multicritical behaviours take place in the ( i1 , α0 ) phase diagrams

Phase diagrams and magnetic behavior of films with amorphization and anisotropy in surfaces

The phase diagrams and magnetic behavior of thin films with two amorphous surfaces are investigated by the use of the effective field theory with correlations. The transition temperature dependence of the exchange integral at surfaces, coupling between surface and nearest-layers, film thickness, and structural fluctuations are studied. Some interesting phenomena can occur as wetting phenomena and compensation point.The phase diagrams and magnetic behavior of thin films with two amorphous surfaces are investigated by the use of the effective field theory with correlations. The transition temperature dependence of the exchange integral at surfaces, coupling between surface and nearest-layers, film thickness, and structural fluctuations are studied. Some interesting phenomena can occur as wetting phenomena and compensation point

Numerical study of rice-pile model

A one-dimensional model of a rice-pile is numerically studied for different driving mechanisms. We found that for a sufficiently large system, there is a sharp transition between the trivial behaviour of a 1D BTW model and self-organized critical (SOC) behaviour. Depending on the driving mechanism, the self-organized critical rice-pile model belongs to two different universality classes.A one-dimensional model of a rice-pile is numerically studied for different driving mechanisms. We found that for a sufficiently large system, there is a sharp transition between the trivial behaviour of a 1D BTW model and self-organized critical (SOC) behaviour. Depending on the driving mechanism, the self-organized critical rice-pile model belongs to two different universality classes

A simulation study of an asymmetric exclusion model with disorder

On the one hand, using numerical simulations, we study the asymmetric exclusion model with open boundaries, particlewise disorder. The phase diagram in the (α , β)   -plane displays high density, low density and maximum current phases, with the first order transition line between high and low density phases shifted away from the line α =β. Within the low density phase a platoon phase transition occurs, many features of which can be explained using exact results for asymmetric exclusion with particlewise disorder on the ring. In a certain region of parameter space the disorder induces a cusp in the current-density relation at maximum flow. Our simulations indicate that this does not affect the topology of the phase diagram, nor the familiar 1/Öx -decay of the density profile in the maximum current phase. On the other hand, we study the effects of defects in the road and of jumping rate ∆t on the phase diagram J−ρ, using asymmetric exclusion model with periodic boundaries. For different level of disorder, the space-time evolution of particles displays «waves» for both phases low density and high density. Besides, there exist two critical values of density, a lower critical value ρc1 and a upper critical value ρc2, in between the current is constant and reaches its maximal value Jmax which increases with increasing the jumping rate ∆t and/or the degree of disorder c. Increasing ∆t and/or c, ρc1 increases and ρc2 decreases.On the one hand, using numerical simulations, we study the asymmetric exclusion model with open boundaries, particlewise disorder. The phase diagram in the (α , β)   -plane displays high density, low density and maximum current phases, with the first order transition line between high and low density phases shifted away from the line α =β. Within the low density phase a platoon phase transition occurs, many features of which can be explained using exact results for asymmetric exclusion with particlewise disorder on the ring. In a certain region of parameter space the disorder induces a cusp in the current-density relation at maximum flow. Our simulations indicate that this does not affect the topology of the phase diagram, nor the familiar 1/Öx -decay of the density profile in the maximum current phase. On the other hand, we study the effects of defects in the road and of jumping rate ∆t on the phase diagram J−ρ, using asymmetric exclusion model with periodic boundaries. For different level of disorder, the space-time evolution of particles displays «waves» for both phases low density and high density. Besides, there exist two critical values of density, a lower critical value ρc1 and a upper critical value ρc2, in between the current is constant and reaches its maximal value Jmax which increases with increasing the jumping rate ∆t and/or the degree of disorder c. Increasing ∆t and/or c, ρc1 increases and ρc2 decreases