Monte Carlo simulation of Ising model on directed Barabasi-Albert network

The existence of spontaneous magnetization of Ising spins on directed Barabasi-Albert networks is investigated with seven neighbors, by using Monte Carlo simulations. In large systems we see the magnetization for different temperatures T to decay after a characteristic time tau, which is extrapolated to diverge at zero temperature.Comment: Error corrected, main conclusion unchanged; for Int. J. Mod. Phys. C 16, issue 4 (2005

Reexamination of scaling in the five-dimensional Ising model

In three dimensions, or more generally, below the upper critical dimension, scaling laws for critical phenomena seem well understood, for both infinite and for finite systems. Above the upper critical dimension of four, finite-size scaling is more difficult. Chen and Dohm predicted deviation in the universality of the Binder cumulants for three dimensions and more for the Ising model. This deviation occurs if the critical point T = Tc is approached along lines of constant A = L*L*(T-Tc)/Tc, then different exponents a function of system size L are found depending on whether this constant A is taken as positive, zero, or negative. This effect was confirmed by Monte Carlo simulations with Glauber and Creutz kinetics. Because of the importance of this effect and the unclear situation in the analogous percolation problem, we here reexamine the five-dimensional Glauber kinetics.Comment: 8 pages including 5 figure

The nonlinear self-defocusing electromagnetic surface waves in a metalised ferrite film

The dispersion relations for TE s-polarized nonlinear electromagnetic surface waves guided by a metallised ferrite film, surrounded by a nonlinear self-defocusing dielectric cover with intensity dependent refractive indices have been computed. Numerical results are also illustrated to show the propagation characteristics for different values of the film thickness, and at a fixed value of the dielectric-ferrite interface nonlinearity. It has been found that the surface waves exist in both directions of propagation, where the external field is applied. The propagation of these waves is non-reciprocal, and has a resonant interaction in the reverse direction. The power flow carried by the structure has also been calculated for different values of the slab thickness. The non-reciprocity has also been obsorved, and the power flow level can been controlled by the film thickness. of semi-infinite gyromagnetic and nonlinear media2

Electron Transport in a Quantum Wire: Effect of a High-Frequency Electromagnetic Field

In this paper, we investigate the electron transport properties in a semiconductor quantum wire, where a finite-rang high-frequency electromagnetic field in the ballistic limit is imposed. Within the effective mass free-electron approximation, the scattering matrix for the system has been formulated by means of a time dependent mode matching method. Some interesting properties of the electron transmission for the system have been shown. It is found that, although the electrons in a nanowire only suffer from lateral collisions with photons, the reflection of electrons also takes place. And when the frequency of the electromagnetic field is resonant with the two lateral energy levels, the field induced inter subband transition dominates the process, and there is a steparising on the transmission as a function of the incident electron energy. Moreover, the transmission dependence on the mode coupling is also discussed

Gray and dark spatial solitary waves in Left handed waveguide structure

The propagation characteristics of both TE gray and dark solitary waves in a waveguide structure consisting of left handed material LH film sandwiched in a nonlinear defocusing medium is investigated. In (LH) film both permittivity and magnetic permeability are negative in definite frequency range. We study dispersion and grayness properties of the solitary waves. We found that the implementation of the left handed material stimulate the backward traveling of the waves with high intensity at the film boundaries. We also found that higher values of wave's grayness are obtained for relatively small magnetic permeability of LH film. These results may be used in designing microwave-photonic devices which have found increasing use in information and telecommunication technologies

Simulation of Demographic Change in Palestinian Territories

Mortality, birth rates and retirement play a major role in demographic changes. In most cases, mortality rates decreased in the past century without noticeable decrease in fertility rates, this leads to a significant increase in population growth. In many poor countries like Palestinian territories the number of births has fallen and the life expectancy increased. In this article we concentrate on measuring, analyzing and extrapolating the age structure in Palestine a few decades ago into future. A Fortran program has been designed and used for the simulation and analysis of our statistical data. This study of demographic change in Palestine has shown that Palestinians will have in future problems as the strongest age cohorts are the above-60-year olds. We therefore recommend the increase of both the retirement age and women employment.Comment: For Int. J. Mod. Phys. C 18, issue 11; 9 pages including figures and progra

Highly Nonlinear Ising Model and Social Segregation

The usual interaction energy of the random field Ising model in statistical physics is modified by complementing the random field by added to the energy of the usual Ising model a nonlinear term S^n were S is the sum of the neighbor spins, and n=0,1,3,5,7,9,11. Within the Schelling model of urban segregation, this modification corresponds to housing prices depending on the immediate neighborhood. Simulations at different temperatures, lattice size, magnetic field, number of neighbors and different time intervals showed that results for all n are similar, expect for n=3 in violation of the universality principle and the law of corresponding states. In order to find the critical temperatures, for large n we no longer start with all spins parallel but instead with a random configuration, in order to facilitate spin flips. However, in all cases we have a Curie temperature with phase separation or long-range segregation only below this Curie temperature, and it is approximated by a simple formula: Tc is proportional to 1+m for n=1, while Tc is roughly proportional to m for n >> 1.Comment: 10 pages including many figure