International Journal of Modern Physics C

In this paper, we study a model of opinion spreading and consensus formation on a square lattice. Given a two-dimensional square lattice with periodic boundary condition, a total fraction p of the sites are occupied by agents. We take into account the drift ability of the focal agents whose opinions' difference is too large. The dynamics of the model is governed by the following two rules. At each time step, the agents (or individuals) can exchange their opinions with those of their neighbors if the difference between them is smaller than the "bounded confidence" ∊; Otherwise, one can move to a vacancy location if permitted (i.e., there are any empty sites existing among the focal agent's neighborhood). The distribution of opinions over the population evolves toward either a consensus state that all individuals share the same opinion or polarization and fragmentation states where two or more opinions can coexist. The statistical properties of this final state vary considerably as the parameters p and ∊ change. It is shown that, when dispersal abilities of the individuals are considered, the bounded confidence which is required to attain consensus can be remarkably decreased.

Studied in this paper is the control problem of hyperchaotic systems. By combining Takagi–Sugeno (T–S) fuzzy model with parallel distributed compensation design technique, we propose a delay-dependent control criterion via pure delayed state feedback. Because the result is expressed in terms of linear matrix inequalities (LMIs), it is quite convenient to check in practice. Based on this criterion, a procedure is provided for designing fuzzy controller for such systems. This method is a universal one for controlling continuous hyperchaotic systems. As illustrated by its application to hyperchaotic Chen's system, the controller design is quite effective.

Monte Carlo simulations using the recently proposed Wang–Landau algorithm are performed to the q = 8 state Potts model in two dimension with various degrees of randomness. We systematically studied the effect of quenched bond randomness to system which has first-order phase transition. All simulations and measurements were done from pure case r = 1 to r = 0.4. Physical quantities such as energy density and ground-state entropy were evaluated at all temperatures. We have also obtained probability distributions of energy to monitor softening of transitions. It appears quite feasible to simulate spin systems with quenched bond randomness by Wang–Landau algorithm.

In this paper, the effects of viscous dissipation in electro-osmotic flow in microchannels are numerically analyzed with lattice Boltzmann method (LBM), and three different lattice Boltzmann models that can recover the macroscopic governing equations for electro-osmotic flow (EOF) are proposed. As the dimensions of the channels approach the microlevel, viscous dissipation could be significant due to a high velocity gradient in electric double layer (EDL). Numerical results show that viscous dissipation plays an important role in EOF in microchannels.

In this paper an expert system is presented that was developed with the aim to analyze electron spectra on the threshold energies in collision with triatomic and polyatomic molecules. This expert system was made by updating the expert system for the analysis of the threshold spectra of two-atomic molecules. In contrast to the threshold spectra of two-atomic molecules, where were exist more or less defined structures of excited states, as well as vibrational levels, in the threshold spectra of triatomic molecules clearly defined structures almost do not exist. The application of the expert system in the process of triatomic and polyatomic molecules spectra analysis has an important role because it enables analysis of larger number of excited states, vibrational levels, and resonances, which can be missed in the analysis by classical methods, either because of low intensity or because of insufficiently defined separation of peaks in spectrum, which arise from the overlapping of a large number of peaks.

In this paper, the updating of the intermediate velocity in the correction stage in SIMPLE-like algorithms on staggered grid is discussed in detail, based on the discussion CLEARER algorithm that is extended from the non-staggered grid to the staggered grid. The performance of SIMPLER and CLEARER algorithms are compared using two numerical examples with reliable solutions. The results show that CLEARER can predict the numerical results as accurately as SIMPLER, and it can also enhance the convergence rate greatly under low under-relaxation factors. In some cases CLEARER algorithm can only need 27% of iteration number required by SIMPLER to reach the same convergence criterion.

The collaboration network is an example of a social network which has both non-trivial temporal and spatial dependence. Based on the observations of collaborations in Physical Review Letters, a model of collaboration network is proposed which correctly reproduces the time evolution of the link length distributions, clustering coefficients, degree distributions, and assortative property of real data to a large extent.

In this paper we extend the investigation of cooperation in some classical evolutionary games on populations where the network of interactions among individuals is of the scale-free type. We show that the update rule, the payoff computation and, to some extent the timing of the operations, have a marked influence on the transient dynamics and on the amount of cooperation that can be established at equilibrium. We also study the dynamical behavior of the populations and their evolutionary stability.

In this paper, a generalized sub-equation expansion method is presented for constructing some exact analytical solutions of nonlinear partial differential equations. Making use of the method and symbolic computation, we investigate the inhomogeneous nonlinear Schrödinger equation (INLSE) with the loss/gain and the frequency chirping and obtain rich exact analytical solutions. From our results, many known results of some nonlinear Schrödinger equations can be recovered by means of some suitable selections of the arbitrary functions and arbitrary constants. With computer simulation, the main soliton features of bright and dark solitons, Jacobi elliptic function solutions, and Weierstrass elliptic function solutions are shown by some figures. Nonlinear dynamics of the chirped soliton pulses is also investigated under the different regimes of soliton management. The method developed does provide a systematic way to generate various exact analytical solutions for INLSE with varying coefficients.

Time evolution of number of cities, population of cities, world population, and size distribution of present languages are studied in terms of a new model, where population of each city increases by a random rate and decreases by a random division. World population and size distribution of languages come out in good agreement with the available empirical data.

Outlet boundary conditions for fully developed flow are discussed for a two-dimensional lattice Boltzmann BGK model (LBGK), and most of the existing ones are found to be incapable of ensuring mass conservation of the whole flow field. Based on this analysis, a mass modified outlet boundary is proposed, which can completely overcome this shortcoming. Tests were done against a two-dimensional plane channel flow and flow over a backward-facing step. The results show that the present method is of good accuracy, stability, and fast convergence, especially for relatively high relaxation time and relatively small lattice number. It can improve the accuracy of the numerical results as well as save the computational time.

The AutoRegressive Conditional Heteroskedasticity (ARCH) and its generalized version (GARCH) family of models have grown to encompass a wide range of specifications, each of them is designed to enhance the ability of the model to capture the characteristics of stochastic data, such as financial time series. The existing literature provides little guidance on how to select optimal parameters, which are critical in efficiency of the model, among the infinite range of available parameters. We introduce a new criterion to find suitable parameters in GARCH models by using Markov length, which is the minimum time interval over which the data can be considered as constituting a Markov process. This criterion is applied to various time series and its results support the known idea that GARCH(1, 1) model works well.