卷 62, 编号 11 (2017)

The problem of radiation of the eigenmodes of an infinite 2D array of semi-infinite coupled slot lines is solved. An analytical solution for the electric field on conductors is found by the Wiener–Hopf method in the approximation of narrow conductors forming the slot lines. An algorithm of numerical implementation of this solution is developed. Expressions for elements of the scattering matrix of an infinite array are found. Dependences of the elements of the scattering matrix on frequency and the structure parameters are studied numerically.

A method for calculation of the input impedance of a stripline dipole (SD) conformally situated on a dielectric cylinder is developed. A singular integral equation (SIE) for the unknown current density distribution function on the SD surface is obtained. A numerical method for solution of this SIE is described. The dependence of the input impedance on the SD length is obtained.

The problems of synthesis of bifocal, trifocal, and quadrifocal constrained lenses with symmetric focal curves are solved. The solution of the problem for the shape of the lens surface in the first case is obtained in the explicit analytical form and, in the other cases, in a parametric analytical form. Based on the numerical study of the eikonal, parameters of the lenses are optimized and the analysis of the eikonal aberrations of the optimized lenses is performed for two values of the maximum angle of view: 60° and 90°. The results of a numerical experiment for a planar constrained quadrifocal lens and a maximum angle of view of 60° are presented.

A periodic component of the ac electrode voltage (electrode noise) is revealed in experiments. The frequency of the periodic component is equal to the pulsation frequency of the flow velocity of liquid in which the electrode sensor is immersed. For the electrode sensor that moves in liquid such a component of the electrode noise may prevail and determine the sensitivity. The sensitivity of a sensor with stainless-steel electrodes with respect to the velocity pulsations is determined to be 1.2 × 10⁻⁶ V s/m. Pulsations of the electrode potential can be interpreted using variations in the rate of electrochemical reaction on the electrode surface.

The potential efficiency of data transmission systems in channels with quasi-pulsed radio interferences of the natural and industrial type has been estimated. The lognormal model of pulsed interference components has been used.

This paper presents the results on whispered speech recognition using gammatone filterbank cepstral coefficients for speaker dependent mode. The isolated words used for this experiment are taken from the Whi-Spe database. Whispered speech recognition is based on dynamic time warping and hidden Markov models methods. The experiments are focused on the following modes: normal speech, whispered speech and their combinations (normal/whispered and whispered/normal). The results demonstrated an important improvement in recognition after application of cepstral mean subtraction, especially in mixed train/test scenarios.

A method for detection and study of chaotic synchronization of cascade coupled single ring continuous phase-locked-loop systems is based on the determination of the phase of chaotic signal using continuous wavelet transform and the subsequent monitoring of phases on time (frequency) scales. Morlet, Gauss, Shannon, and B-spline complex wavelets are studied. The results of mathematical simulation are presented. Signal-to-noise ratios that allow chaotic phase synchronization are estimated.

The problem of formation of a ribbon beam with the cross section shaped as an elongated parallelogram, which is typical of electron-optical systems of planar gyrotrons due to the drift velocity along the cyclic coordinate, is solved. A local solution of the Laplace equation in the case of the temperature-limited emission near the cathode edge is constructed in the general case of 2D flows with nonuniform beam parameters. In contrast to arbitrary setting of the electrode geometry in this region, this solution does not violate the adopted hydrodynamic model of the flow. The results corresponding to typical parameters of a planar gyrotron are presented.

The synthesis method of electro-optical systems forming converging sheet electron beams at partial magnetic shielding of the cathode is developed. Equations of the inerior and exterior problems of the synthesis method and an equation for estimation of the deformation of the configuration of the sheet electron beam in the transit channel are obtained in the paraxial approximation. The proposed method is used to simulate electron guns forming converging sheet electron beams with the electrical parameters similar to the parameters of the uncompressed electron beam for terahertz radiation sources.

The generalized ambiguity function in spatial coordinates and its approximate analytical representation are obtained for the multifrequency multiple-input multiple-output (MIMO) synthetic-aperture radar (SAR) system. The examples in which ambiguity-function cross sections in range and azimuth are calculated in the Earth remote sensing problem for the MIMO SAR system installed on a spacecraft and compared with those for the classical SAR system are presented. In the case of the MIMO SAR system, the physical meaning and the practical importance of an increase in azimuthal resolution are explained.