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Dmitry Pozdnyakov

Publications and source records attributed to Dmitry Pozdnyakov.

12 recordsLinked to original sources
arXiv2026

Image Denoising via the Adaptive Rank-Cluster Filter

A spatial-local image-denoising filter is proposed, and its performance metrics are evaluated in comparison with baseline filtering algorithms, including the median, adaptive median, Gaussian, bilateral, Wiener, anisotropic diffusion, and non-local means. The developed filter is based on aligning the intensity value of the central pixel in a 3x3 window with the statistical majority intensity of one of the two clusters formed by optimal Otsu's partitioning of a pixel set sorted by intensity and trimmed to seven elements. This is followed by a fuzzy fusion of the calculated value with the median intensity of the pixels within the window. The proposed filter demonstrates the highest robustness to variations in image noise levels, particularly when processing mixed noise consisting of salt-and-pepper impulse noise and additive Gaussian noise in various proportions

cs.CV↗
arXiv2020

Fisheye lens distortion correction

A new distortion correction algorithm for fisheye lens with equidistant mapping function is considered in the present study. The algorithm is much more data lossless and accurate than such a classical approach like Brown-Conrady model

eess.IV↗
arXiv2020

Determination of the most representative descriptor among a set of feature vectors for the same object

On an example of solution of the face recognition problem the approach for estimation of the most representative descriptor among a set of feature vectors for the same face is considered in present study. The estimation is based on robust calculation of the mode-median mixture vector for the set as the descriptor by means of Welsch/Leclerc loss function application in case of very sparse filling of the feature space with feature vectors

cs.CV↗
arXiv2015

Physical interpretation of the Riemann hypothesis

An equivalent formulation of the Riemann hypothesis is given. The physical interpretation of the Riemann hypothesis equivalent formulation is given in the framework of quantum theory terminology. One more power series related to the Riemann Xi function and the Riemann hypothesis is considered. Some roots of the polynomial connected with the power series are studied. It is shown that the Riemann hypothesis is true. But it is undecidable and must be considered as an axiom.

math.GM↗
arXiv2014

Scattering of electrons by ionized impurities in semiconductors: quantum-mechanical approach to third body exclusion

As applied to the numerical simulation of electron transport and scattering processes in semiconductors an efficient model describing the scattering of electrons by the ionized impurities is proposed. On the example of GaAs at 77 and 300 K and Si at 300 K the dependencies of low-field electron mobility on the donor impurity concentration in the semiconductors are calculated in the framework of proposed model as well as in the framework of such most frequently used applied models as the Conwel-Weisskopf model and the Brooks-Herring one. After comparing the calculation results with the well-known experimental data it has been ascertained that the best agreement between the theory and experiment is achieved with application of the proposed model.

physics.gen-ph↗
arXiv2013

Validity of approximations applied in calculations of single-wall metallic carbon nanotube current-voltage characteristics

The calculation results of dependencies of electric current in the infinitely long single-wall metallic carbon nanotubes of armchair type with different diameter values on the strength of constant and uniform longitudinal electric field applied to them are presented in this study. On the one hand the results have been obtained by an accurate numerical self-consistent tight-binding full-band solution of the Boltzmann transport equations for electrons and phonons in the electric quantum limit. On the other hand the results have been obtained by solution of these equations after application of a number of commonly used simplifications and approximations. It is ascertained that the approximately calculated dependencies considerably diverge from the rigorously calculated ones. In addition the relaxation time of non-equilibrium phonons in the single-wall metallic carbon nanotubes has been estimated by means of comparison of the calculation results with the well-known experimental data. Its value is equal to 2.2+/-0.1 ps.

cond-mat.mes-hall↗
arXiv2008

Electron drift velocity control in GaAs-in-Al2O3 quantum wire transistor structure due to the electron scattering rate alteration

Electron transport in the transistor structure based on thin undoped GaAs-in-Al2O3 quantum wire is simulated by ensemble Monte-Carlo method taking into account electron scattering by the phonons and surface roughness. The influence of surface roughness height on electron drift velocity at 77 and 300 K is investigated for the values of longitudinal electric field strength of 0.1 and 1.0 kV/cm. A possibility of electron drift velocity control due to variation of the bias applied to the gates, which results in the electron scattering rate alteration, is ascertained.

cond-mat.mes-hall↗
arXiv2006

Electron Scattering in Thin GaAs Quantum Wires

In this paper the scattering rates of electrons in thin free standing GaAs quantum wires in the electric quantum limit are calculated self-consistently taking into account the collisional broadening caused by scattering processes. The following mechanisms of scattering are considered: one-dimensional acoustic and polar optical phonons, surface roughness and ionized impurities. The non-parabolicity of electron energy spectrum is also taken into account.

cond-mat.mes-hall↗
arXiv2006

Self-consistent calculations of phonon scattering rates in GaAs transistor structure with one-dimensional electron gas

Self-consistent calculations of acoustic and polar optical phonon scattering rates in GaAs quantum wire transistor structures were carried out with account of collisional broadening. The influence of the gate bias on the scattering rates was examined, too. It was shown that in order to treat the scattering rates rigorously it is important to search for electron energy levels by means of the self-consistent solution of Schrodinger and Poisson equations and to take into account the collisional broadening.

cond-mat.mes-hall↗
arXiv2006

Ionized Impurity and Surface Roughness Scattering Rates of Electrons in Semiconductor Structures with One-Dimensional Electron Gas and Broadened Energy Levels

An approach to calculation of the ionized impurity and surface roughness scattering rates of electrons in very thin semiconductor quantum wires taking into account the energy level broadening is worked out. It is assumed that all the electrons in the structure are in the electric quantum limit. The screening is taken into account while considering the ionized impurity scattering. Comparison of the surface roughness scat-tering rates calculated using the exponential and Gaussian autocorrelation functions is done.

cond-mat.mes-hall↗
arXiv2006

Electron transport in armchair single-wall carbon nanotubes

The rates of electron scattering via phonons in the armchair single-wall carbon nanotubes were calculated by using the improved scattering theory within the tight-binding approximation. Therefore, the problem connected with the discrepancy of the scattering rates calculated in the framework of the classical scattering theory and ones predicted by experimental data was clarified. Then these results were used for the solving of the kinetic Boltzmann equation to describe electron transport properties of the nanotubes. The equation was solved numerically by using both the finite difference approach and the Monte Carlo simulation procedure.

cond-mat.mes-hall↗