arXiv subjects

A. K. Aringazin

Publications and source records attributed to A. K. Aringazin.

At least 19 recordsLinked to original sources

arXiv2016

Phonon assisted resonant tunnelling and its phonons control

We observe a series of sharp resonant features in the tunnelling differential conductance of InAs quantum dots. We found that dissipative quantum tunnelling has a strong influence on the operation of nano-devices. Because of such tunnelling the current-voltage characteristics of tunnel contact created between atomic force microscope tip and a surface of InAs/GaAs quantum dots display many interesting peaks. We found that the number, position, and heights of these peaks are associated with the phonon modes involved. To describe the found effect we use a quasi-classical approximation. There the tunnelling current is related to a creation of a dilute instanton-anti-instanton gas. Our experimental data are well described with exactly solvable model where one charged particle is weakly interacting with two promoting phonon modes associated with external medium. We conclude that the characteristics of the tunnel nanoelectronic devices can thus be controlled by a proper choice of phonons existing in materials, which are involved.

cond-mat.mes-hall↗

arXiv2007

Theory of Acoustic Emission for Micro-Cracks Appeared Under the Surface Layer Machining by Compressed Abrasive

One of the possible mechanisms for acoustic emission of growing micro-cracks under conditions of the material machining by com-pressed abrasive has been theoretically studied. Physical ground of this mechanism is the dislocation creep in the field of instant contact temperature on stage of micro-cutting with appearance of the wedge-shaped cavity. It has been shown that the energy density for radiated acoustic wave at the moment when the cavity is opened essentially depends on parameters of the material abrasive machining.

cond-mat.mtrl-sci↗

arXiv2006

Acoustic Emission of Growing Microcracks in Vibration-Loaded Material

We propose mechanism describing an acoustic emission by growing microcracks in the material under external cycled load. We use the theoretical approach based on Huygens principle for elastic solid con-tinuum with an account for dislocation creep in the zone of abrasive action. We show that the acoustic emission is anisotropic and its main direction depends not only on the effective length of microcrack but also on dynamics of dislocation structure and on diffusion processes in Kottrell zone which give rise to microcracks.

cond-mat.mtrl-sci↗

arXiv2005

Magneto-optics of multi-well quantum structures with D2- centres

The problem of electron binding states in field of two D0 centres in semiconductive quantum well (QW) in the presence of an external longitudinal magnetic field (along the QW growth axis) is studied within the framework of zero-range potential model. It is found that the magnetic field leads to a considerable change in positions of g- and u-terms, and to a stabilization of the D2- states in QW. It is shown that a form of impurity magneto-optical absorption spectrum essentially depends on the light polarization direction and on the spatial configuration of the D2- molecular ion in QW.

cond-mat.stat-mech↗

arXiv2005

Dissipative tunneling in structures with quantum dots and quantum molecules

The problem of tunneling control in systems "quantum dot - quantum well" (as well as "quantum dot - quantum dot" or quantum molecule) and "quantum dot - bulk contact" is studied as a quantum tunneling with dissipation process in the semiclassical (instanton) approximation. For these systems temperature and correlation between a quantum dot radius and a quantum well width (or another quantum dot radius) are considered to be control parameters. The condition for a single electron blockade is found in the limit of quantum dot. The criteria for an extreme tunneling current in quantum molecules are also presented. The tunnel probability for systems under investigation is analytically obtained as well.

cond-mat.stat-mech↗

arXiv2005

Stochastic models of Lagrangian acceleration of fluid particle in developed turbulence

Modeling statistical properties of motion of a Lagrangian particle advected by a high-Reynolds-number flow is of much practical interest and complement traditional studies of turbulence made in Eulerian framework. The strong and nonlocal character of Lagrangian particle coupling due to pressure effects makes the main obstacle to derive turbulence statistics from the three-dimensional Navier-Stokes equation; motion of a single fluid-particle is strongly correlated to that of the other particles. Recent breakthrough Lagrangian experiments with high resolution of Kolmogorov scale have motivated growing interest to acceleration of a fluid particle. Experimental stationary statistics of Lagrangian acceleration conditioned on Lagrangian velocity reveals essential dependence of the acceleration variance upon the velocity. This is confirmed by direct numerical simulations. Lagrangian intermittency is considerably stronger than the Eulerian one. Statistics of Lagrangian acceleration depends on Reynolds number. In this review we present description of new simple models of Lagrangian acceleration that enable data analysis and some advance in phenomenological study of the Lagrangian single-particle dynamics. Simple Lagrangian stochastic modeling by Langevin-type dynamical equations is one the widely used tools. The models are aimed particularly to describe the observed highly non-Gaussian conditional and unconditional acceleration distributions. Stochastic one-dimensional toy models capture main features of the observed stationary statistics of acceleration. We review various models and focus in a more detail on the model which has some deductive support from the Navier-Stokes equation. Comparative analysis on the basis of the experimental data and direct numerical simulations is made.

cond-mat.stat-mech↗

arXiv2004

Conditional Lagrangian acceleration statistics in turbulent flows with Gaussian distributed velocities

The random intensity of noise approach to one-dimensional Laval-Dubrulle-Nazarenko type model having deductive support from the three-dimensional Navier-Stokes equation is used to describe Lagrangian acceleration statistics of a fluid particle in developed turbulent flows. Intensity of additive noise and cross correlation between multiplicative and additive noises entering a nonlinear Langevin equation are assumed to depend on random velocity fluctuations in an exponential way. We use exact analytic result for the acceleration probability density function obtained as a stationary solution of the associated Fokker-Planck equation. We give a complete quantitative description of the available experimental data on conditional and unconditional acceleration statistics within the framework of a single model with a single set of fit parameters. The acceleration distribution and variance conditioned on Lagrangian velocity fluctuations, and the marginal distribution calculated by using independent Gaussian velocity statistics are found to be in a good agreement with the recent high-Reynolds-number Lagrangian experimental data. The fitted conditional mean acceleration is very small, that is in agreement with DNS, and increases for higher velocities but it departs from the experimental data, which exhibit anisotropy of the studied flow.

cond-mat.stat-mech↗

arXiv2004

The conditional mean acceleration of fluid particle in developed turbulence

Using the random intensity of noise (RIN) approach to the one-dimensional Laval-Dubrulle-Nazarenko type model for the Lagrangian acceleration in developed turbulence [cond-mat/0305186, cond-mat/0305459] we study the probability density function and mean acceleration conditional on velocity fluctuations. The additive noise intensity and the cross correlation between the additive and multiplicative noises are assumed to be dependent on velocity fluctuations in an exponential way. The obtained fit results are found to be in a good qualitative agreement with the recent experimental data on the conditional acceleration statistics by Mordant, Crawford, and Bodenschatz. The fit to the observed conditional mean acceleration is of pure illustrative character which is performed to study influence of variation of the cross correlation parameter on the shape of conditional acceleration distribution and conditional acceleration variance. The conditional mean acceleration should be zero for homogeneous isotropic turbulence. The observed conditional mean acceleration increases for bigger velocity fluctuation amplitude and is associated to anisotropy of the studied flow.

cond-mat.stat-mech↗

arXiv2004

Skewness of probability density functions of fluid particle acceleration in developed turbulence

Within the framework of one-dimensional Laval-Dubrulle-Nazarenko type model for the Lagrangian acceleration in developed turbulence studied in the work [A.K. Aringazin and M.I. Mazhitov, cond-mat/0305186] we focus on the effect of correlation between the multiplicative noise and the additive one which models the relationship between the stretching and vorticity, and can be seen as a skewness of the probability density function of some acceleration component. The skewness of the acceleration distribution in the laboratory frame of reference should be zero in the ideal case of statistically homogeneous and isotropic developed turbulent flows but when considering acceleration component aligned to fluid particle trajectories it is of much importance in understanding of the cascade picture in the three-dimensional turbulence related to Kolmogorov four-fifths law. We illustrate the effect of nonzero cross correlation parameter $λ$. With $λ=-0.005$ the transverse ($x$) acceleration probability density function turns out to be in good agreement with the recent experimental data by Mordant, Crawford, and Bodenschatz. In the Random Intensity of Noise (RIN) approach, we study the conditional probability density function and conditional mean acceleration assuming the additive noise intensity to be dependent on velocity fluctutions.

cond-mat.stat-mech↗

arXiv2003

Gaussian factor in the distribution arising from the nonextensive statistics approach to fully developed turbulence

We propose a simple modification, the Gaussian truncation, of the probability density function which was obtained by Beck (2001) to fit the experimental distribution of fluid particle acceleration component from fully developed fluid turbulence inspired by the framework of nonextensive statistical mechanics with the underlying gamma distribution of the model parameter. The modified distribution is given a phenomenological treatment and provides a good fit to new experimental results on the acceleration of fluid particle reported by Crawford, Mordant, and Bodenschatz. We compare the results with the new fit which was recently obtained by Beck (2002) with the use of the underlying log-normal distribution of the model parameter.

cond-mat.stat-mech↗

arXiv2003

Stochastic model of the conditional acceleration of a fluid particle in developed turbulence

The random intensity of noise approach to 1D Laval-Dubrulle-Nazarenko model is used to describe Lagrangian acceleration of a fluid particle in developed turbulence. Intensities of noises entering nonlinear Langevin equation are assumed to depend on random velocity fluctuations in an exponential way. The conditional acceleration PDF, variance, and mean are found to be in a good qualitative agreement with the recent high-Re Lagrangian experimental data.

cond-mat.stat-mech↗

arXiv2003

One-dimensional Langevin models of fluid particle acceleration in developed turbulence

We make a comparative analysis of some recent one-dimensional Langevin models of the acceleration of a Lagrangian fluid particle in developed turbulent flow. The class of models characterized by random intensities of noises (RIN models) provides a fit to the recent experimental data on the acceleration statistics. We review the model by Laval, Dubrulle, and Nazarenko (LDN) formulated in terms of temporal velocity derivative in the rapid distortion theory approach, and propose its extension due to the RIN framework. The fit of the contribution to fourth order moment of the acceleration is found to be better than in the other stochastic models. We study the acceleration probability density function conditional on velocity fluctuations implied by the RIN approach to LDN type model. The shapes of the conditional distributions and the conditional acceleration variance have been found in a good agreement with the recent experimental data by Mordant, Crawford, and Bodenschatz (2003).

cond-mat.stat-mech↗

arXiv2003

Magneto-optical properties of the quantum dot - impurity center systems synthesized in a transparent dielectric matrix

Magneto-optical absorption by the quantum dot (QD) with impurity center (IC or D(-)-center) complexes synthesized in a transparent dielectric matrix, with consideration of the QD size dispersion, is theoretically studied. Within the framework of effective mass approach, the analytical expression for the light impurity magneto-optical absorption coefficient for both the longitudinal and transversal polarizations with respect to the direction of external quantizing magnetic field is calculated.

cond-mat.mtrl-sci↗

arXiv2003

Two-dimensional tunnel bifurcations with dissipation

Two-particle tunneling in synchronous and asynchronous regimes is studied in the framework of dissipative quantum tunneling. We show that the use of the proposed model is justified by a comparison with realistic potential energy surfaces of porphyrin and experimental dependence of the reaction rate on temperature. The critical temperature T_c corresponding to a bifurcation of the underbarrier trajectory is determined. The effect of a heat bath local mode on the probability of two-dimensional tunneling transfer is also investigated. At certain values of the parameters, the degeneracy of antiparallel tunneling trajectories is important. Thus, four, six, twelve, etc., pairs of the trajectories should be taken into account (a cascade of bifurcations). For the parallel particle tunneling the bifurcation resembles phase transition of a first kind, while for the antiparallel transfer it behaves as second order phase transition. The proposed theory allows for the explanation of experimental data on quantum fluctuations in two-proton tunneling in porphyrins near the critical temperature.

cond-mat.soft↗

arXiv2003

Two-dimensional tunnel correlations with dissipation

Tunneling of two particles in synchronous and asynchronous regimes is studied in the framework of dissipative quantum tunneling. The critical temperature T_c corresponding to a bifurcation of the underbarrier trajectory is determined. The effect of a heat bath local mode on the probability of two-dimensional tunneling transfer is also investigated. At certain values of the parameters, the degeneracy of antiparallel tunneling trajectories is important. Thus, four, six, twelve, etc., pairs of the trajectories should be taken into account (a cascade of bifurcations). For the parallel particle tunneling the bifurcation resembles phase transition of a first kind, while for the antiparallel transfer it behaves as second order phase transition. The proposed theory allows for the explanation of experimental data on quantum fluctuations in two-proton tunneling in porphyrins near the critical temperature.

cond-mat.mes-hall↗

arXiv2003

The PDF of fluid particle acceleration in turbulent flow with underlying normal distribution of velocity fluctuations

We describe a formal procedure to obtain and specify the general form of a marginal distribution for the Lagrangian acceleration of fluid particle in developed turbulent flow using Langevin type equation and the assumption that velocity fluctuation $u$ follows a normal distribution with zero mean, in accord to the Heisenberg-Yaglom picture. For a particular representation, $β=\exp[u]$, of the fluctuating parameter $β$, we reproduce the underlying log-normal distribution and the associated marginal distribution, which was found to be in a very good agreement with the new experimental data by Crawford, Mordant, and Bodenschatz on the acceleration statistics. We discuss on arising possibilities to make refinements of the log-normal model.

cond-mat.stat-mech↗

arXiv2003

Magneto-optics of quantum wires with D(-)-centers

The impurity magneto-optical absorption for the cases of longitudinal and transversal light polarization with respect to the quantum wire axis has been theoretically studied. Analytical expressions for the corresponding D(-)-centers photo-ionization cross sections under the action of longitudinal magnetic field have been obtained, and their spectral dependences for InSb quantum wires have been investigated.

cond-mat.str-el↗

arXiv2003

Phenomenological Gaussian screening in the nonextensive statistics approach to fully developed turbulence

We propose a simple phenomenological modification, a Gaussian screening, of the probability distribution function which was obtained by Beck to explain experimentally measured distribution from fully developed fluid turbulence, within the framework of nonextensive statistical mechanics. The modified distribution provides a good fit to new experimental results on the acceleration of fluid particles reported by Crawford, Mordant, and Bodenschatz. Theoretical foundations of such a modification requires a separate study.

cond-mat↗