We derive the semiclassical equations of motion of a transverse acoustical
wave packet propagating in a phononic crystal subject to slowly varying
perturbations. The formalism gives rise to Berry effect terms in the equations
of motion, manifested as the Rytov polarization rotation law and the
polarization-dependent Hall effect. We show that the formalism is also
applicable to the case of non-periodic inhomogeneous media, yielding explicit
expressions for the Berry effect terms.Comment: To appear in JETP Let
We study the polarization transport of transverse phonons by adopting a new
approach based on the quantum mechanics of spin-orbit interactions. This
approach has the advantage of being apt for incorporating fluctuations in the
system. The formalism gives rise to Berry effect terms manifested as the Rytov
polarization rotation law and the polarization-dependent Hall effect. We derive
the distribution of the Rytov rotation angle in the presence of thermal noise
and show that the rotation angle is robust against fluctuations
We study the effect of superdiffusion on the instability in reaction-diffusion systems. It is shown that reaction-superdiffusion systems close to a Turing instability are equivalent to a time-dependent Ginzburg-Landau model and the corresponding free energy is introduced. This generalized free energy which depends on the superdiffusion exponent governs the stability, dynamics, and the fluctuations of reaction-superdiffusion systems near the Turing bifurcation. In addition, we show that for a general n-component reaction-superdiffusion system, a fractional complex Ginzburg-Landau equation emerges as the amplitude equation near a Hopf instability. Numerical simulations of this equation are carried out to illustrate the effect of superdiffusion on spatiotemporal patterns. Finally, the effect of superdiffusion on the instability in the Brusselator model, as a special case of reaction-diffusion systems, is studied. In general, superdiffusion introduces a new parameter that changes the behavior of the system near the instability.
In this paper, the output characteristics of a UV pin array pre-ionized TEA CO 2 laser have been simulated and compared with the associated experimental data. In our simulation, a new theoretical model has been improved for transient behavior analysis of the discharge current pulse. The laser discharge tube was modeled by a nonlinear RLC electric circuit as a real model for electron density calculation. This model was coupled with a six-temperature model (6TM) in order to simulation dynamic emission processes of the TEA CO 2 laser. The equations were solved numerically by the fourth order Runge-Kutta numerical method and some important variables such as current and voltage of the main discharge, resistance of the plasma column and electron density in the main discharge region, were calculated as functions of time. The effects of non-dissociation factor, rotational quantum number and output coupler reflectivity were also studied theoretically. The experimental and simulation results are in good agreement.
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