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Zubko S.P.,St Petersburg Electrotechnical University Leti
Physics of the Solid State

The size effects observed in thin films of displacive ferroelectrics are considered. A model of the dependence of the spontaneous polarization and phase transition temperature on the film thickness is proposed. © 2010 Pleiades Publishing, Ltd. Source

Altmark A.M.,St Petersburg Electrotechnical University Leti | Kanareykin A.D.,Euclid Techlabs LLC
Journal of Physics: Conference Series

In this paper, we give a complete analytical solution for Cherenkov wakefields generated by an azimuthally asymmetric annular beam propagating in a coaxial two-channel dielectric structure. The transformer ratio of this type of structure is dramatically increased in comparison to a cylindrical wakefield accelerating structure. A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects has been upgraded to incorporate annular drive beams and coaxial dielectric wakefield accelerating structures. Beam dynamics simulations of the annular drive beam with asymmetric charge distributions have been carried out to determine the sensitivity of this method to beam imperfections. © Published under licence by IOP Publishing Ltd. Source

Baruzdin S.A.,St Petersburg Electrotechnical University Leti
Technical Physics

The excitation of a spin echo by two pulses with linear frequency modulation, upon which the pulse parameters ensure maximal compression of the response in time, is considered. The frequency of the excitation pulses was changed by a step law, approximating its linear rise. The transfer matrix of the state of the spin system for pulses with linear frequency modulation is found by solving the Bloch equations. The shape of the envelope of the spin echo in thin magnetic cobalt films, as well as the dependence of the echo amplitude on the parameters of the excitation pulses, is determined. The amplitudes of the excitation pulses, which ensure the excitation of the echo maximal amplitude for various values of the frequency deviation, are found. It is shown that the use of pulses with linear frequency modulation makes it possible to obtain the same echo amplitude as with the use of simple excitation pulses for a substantially smaller amplitude and power of excitation pulses. © 2015, Pleiades Publishing, Ltd. Source

Khomyakov M.Y.,St Petersburg Electrotechnical University Leti
Pattern Recognition and Image Analysis

A comparative evaluation of the most commonly used linear methods for edge detection in grayscale images are presented. Detectors based on the first and second derivatives of image brightness are considered. The method for automatic edge tracking in grayscale images is proposed. The model for assessing errors and artifacts caused by sampling during digitization of real input images is proposed. Investigation of edge detectors isotropy and errors caused by input images sampling is conducted. The advantage of the Isotropic operator for edge tracking is shown. The noise immunity of linear edge detection methods is assessed and the superiority of 3 × 3 gradient operators for noisy images is shown. Isotropic and Sobel operators are identified to be optimal on a basis of sampling errors, output noise level, and computational complexity. © 2012 Pleiades Publishing, Ltd. Source

Skobov V.G.,St Petersburg Electrotechnical University Leti | Chernov A.S.,National Research Nuclear University MEPhI
Physics of the Solid State

The influence of nonlinearity on propagation of radio waves into semimetals in the geometry where the constant magnetic field H is directed along the trigonal axis of the crystal has been investigated. Strong magnetic Landau damping occurs in the linear mode in this geometry. It is shown that the electron capture by the magnetic field of a radio frequency wave of large amplitude decreases this absorption. As a result, the depth of the skin layer in the semimetal becomes the function of the amplitude of the exciting radio frequency field and can increase many times. © 2013 Pleiades Publishing, Ltd. Source

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