International Journal of Modern Physics C

Based on the Ising spin system and the Sznajd Model (SM), we introduce a new model to study the opinion evolving in SM on square lattices by numerical simulations. In the model, a panel of four neighboring sites are randomly selected at each Monte Carlo step (MCS), around the panel there are eight nearest neighbors. To be more realistic, two basic impacts are considered in the process of the eight individuals' decision-making, i.e., the information governed by the panel of four neighboring sites and the average opinion of the whole community. It is found that our model show many useful and interesting statistical results.

Based on the Nagel–Schreckenberg (NaSch) model of traffic flow, a new cellular automaton (CA) traffic model is proposed to simulate microscopic traffic flow. The probability p is a variable which contains a randomly selected term for each individual driver and a density-dependent term which is the same for all drivers. When the rational probability p is obtained, the larger value of maximum flow which is close to the observed data can be reached compared with that obtained from the NaSch model. The fundamental diagram obtained by simulation shows the ability of this modified CA model to capture the essential features of traffic flow, e.g., the spontaneous formation of traffic jams and appearance of the metastable state. These indicate that the presented model is more reasonable and realistic.

The unsteady flow within a simplified 3D centrally-actuated type artificial heart was investigated numerically using moving boundary technique. The velocities on the inlet and outlet were determined according to the motion of the diaphragm. The case with heart beat rate of 75 beats per minute (bpm) was simulated. Two models were studied. It is found that, in the diastolic cycle, a vortex ring forms in the conjunction of the blood chamber and the inlet tube. This vortex ring can provide good wash-out on the wall.

In a recent paper [Chaos, Solitons Fractals21, 915 (2004)], both real and complex Van der Pol oscillators were introduced and shown to exhibit chaotic limit cycles. In the present work these oscillators are synchronized by applying an active control technique. Based on Lyapunov function, the control input vectors are chosen and activated to achieve synchronization. The feasibility and effectiveness of the proposed technique are verified through numerical simulations.

An entropic lattice Boltzmann model for gaseous slip flow in microchannels is presented. We relate the Knudsen number with the relaxation time in the lattice Boltzmann evolution equation from the gas kinetic theory. The slip velocity taking the momentum accommodation coefficient into account at the solid boundaries is obtained with kinetic boundary conditions. The two-dimensional micro-Poiseuille flow, microflow over a backward-facing step, micro-lid-driven cavity flow, and three-dimensional microflow are simulated using the present model. Numerical tests show that the results of the present lattice Boltzmann method together with the boundary scheme are in good agreement with the analytical solutions and numerical simulations by the finite volume method.

By introducing the velocity difference between the preceding car and the car before the preceding one into the optimal velocity model (OVM), we present an extended dynamical model which takes into account the next-nearest-neighbor interaction in relative velocity. The stability condition of this model is derived by considering a small perturbation around the uniform flow solution and the validity of our theoretical analysis is also confirmed by direct simulations. The analytic and simulation results indicate that traffic congestion is suppressed efficiently by incorporating the effect of new consideration. Moreover, the effect of the new consideration is investigated by numerical simulation. In particular, the jamming flow, the current-density relation, and the propagation speed of small disturbance are examined in detail by varying various values of the parameter.

This paper exposes a procedure for modeling and solving linear systems using continuous-valued cellular automata. The original part of this work consists on showing how the cells in the automaton may contain both real values and operators for carrying out numerical calculations and solve a desired problem. In this sense the automaton acts as a program, where data and operators are mixed in the evolution space for obtaining the correct calculations. As an example, Euler's integration method is implemented in the configuration space in order to achieve an approximated solution for a dynamical system. Three examples showing linear behaviors are presented.

A model on the effects of leader, media, viruses, worms, and other agents on the opinion of individuals is developed and utilized to simulate the formation of consensus in society and price in market via excess between supply and demand. The effects of some time varying drives (harmonic and hyperbolic) are also investigated.

Two new pseudorandom number generators, based on iterated function systems (IFS), are introduced. An IFS is created based on an arbitrary seed and a set is constructed using the deterministic iteration algorithm (DIA). From this set pseudo random numbers have been constructed. The generators have big periods and pass all major statistical tests, indicating that they can be used in any application requiring random numbers, such as cryptography.

First, a function projective synchronization of two identical systems is defined. Second, based on the active control method and symbolic computation Maple, the scheme of function projective synchronization is developed to synchronize two identical chaotic systems (two identical classic Lorenz systems) up to a scaling function matrix with different initial values. Numerical simulations are used to verify the effectiveness of the scheme.

In this paper, we present the dynamics of disaster spreading from key nodes in complex networks. The key nodes have maximum and minimum out-degree nodes, which show important in spreading disaster. This paper considers directed Erdös–Rényi, scale-free and small-world networks. Using the model considering the common characteristics of infrastructure and lifeline networks, i.e., self-healing function and disaster spreading mechanism, we carry out simulations for the effects of the recovery time parameter and the time delay on the recovery rate and the number of damaged nodes. Simulation results show some typical disaster spreading characteristics, e.g., a non-equilibrium phase transition in the parameter space, disturbance from the maximum out-degree nodes resulting in more damaged effect, etc.

Traffic flow on straight roads is the most common traffic phenomenon in urban road traffic networks. In this paper, a realistic cellular automaton (CA) model is proposed to investigate driver behavior on urban straight roads based on our field observations. Two types of driver behavior, free and car-following, are simulated. Free driving behavior is modeled by a novel five-stage speeding model (two acceleration stages, one steady stage and two deceleration stages). Car-following processes are simulated by using 1.5-s as the average headway (1.5-s rule), which is observed in local urban networks. Vehicular mechanical restrictions (acceleration and deceleration capabilities) are appropriately reflected by a five-stage speeding model, which has the dual-regimes of acceleration and deceleration. A fine grid (the length of each cell corresponds to 1 m) is used. Our simulation results demonstrate that the introduction of the dual-regimes of acceleration and deceleration, 1.5-s rule and fine grid matches actual driver behavior well on urban straight roads.

The Lattice Boltzmann simulation of a flow generated by an oscillating plate is conducted in a wide range of frequency variation 0< ω_τ < ∞. The theoretically predicted transition from the viscoelastic (ω_τ ≪ 1) Newtonian behavior to purely elastic non-Newtonian regime (ω_τ ≫ 1) has been demonstrated. The relation of the derived solutions to microfluidics (high-frequency micro-resonators) is shown on an example of a "plane oscillator".