Том 63, № 6 (2018)

Surface plasmons (polaritons) along the boundary between vacuum and a dissipative half-space with given complex permittivity, including the case of placing an electrically thin dielectric layer (system of layers) on the boundary, are considered. Conditions for transformation of a fast gliding Zenneck surface wave (polariton) into a slow wave (slow surface plasmon) are considered. The behavior of the group velocity and the energy velocity of motion (transfer) in such structures are analyzed. The reflection coefficient of the Zenneck wave along the sea for the ice pack of a given thickness is determined. It has been shown that rigorous solution of the Sommerfeld problem by means of numerical calculation of integrals in the near zone allows obtaining the solution of the inverse problem of the structure of the surface region on the basis of redundant experimental data on components of the electromagnetic field on the surface at different ranges from the antenna.

The problem of calculation of eigenmode characteristics is considered for 3D open dielectric waveguides and waveguides with the anisotropic impedance boundary condition. An efficient algorithm is proposed for finding eigenmodes of waveguides having different cross-sections. It is based on the solution of the auxiliary problem of diffraction of the field of a filamentous source located inside the waveguide. The method is tested using weakly directing dielectric waveguides having circular and elliptical sections and a waveguide with the two-sheeted section. The results of calculation of dielectric waveguides obtained with the help of the proposed method, the method of finite elements, and the method of the integral equation over the waveguide section are compared. The circular and elliptical waveguides and the waveguide having a two-sheeted section with an anisotropic impedance are also investigated. The calculation results are compared with the results obtained with the use of the method of separation of variables and the Galerkin method.

The paper presents a theoretical consideration of a two-dimensional array consisting of two series-connected parts: an infinite system of one-dimensional arrays of strip horns and an array of planar horns. The eigenwave problem for an infinite one-dimensional array of strip transmission lines k]which reduces to a singular integral equation with respect to the current on the strip k]is solved. An analytical solution for the current and an expression for the characteristic impedance of the principal T-wave of the array k]which is valid in the scanning mode k]are found. A model of an array with smoothly varying parameters that describes the operation of a one-dimensional array of strip horns in the approximation of a microwave transmission line is developed. In the same approximation k]a model of an array of planar horns and the entire two-dimensional two-section array is developed and its numerical study is performed.

The results concerning the development and investigation of the algorithms for incoherent detection of orthogonal frequency-division multiplexing signal preambles, which are used to synchronize processes in synchronous systems of discrete data transmission over single- and multibeam channels, are presented. It is demonstrated that the developed detection procedures rely on the stable algorithm of calculation of the sliding spectrum and are alternative to the detection technique based on the fast spectral transform in the Fourier basis with respect to their throughput.

The expression for the complex envelope of the reflected chirp pulse at the input of the radar receiver is derived taking into account the dispersion distortions in the ionosphere in the geometric optics approximation. The relations for the lower limits of the rms values of fluctuation errors of estimates of the radar range and the ionospheric correction as functions of the signal-to-noise ratio, the wavelength, and the relative deviation frequency are obtained. The possibilities of refinement of estimates of the ionospheric correction with the use of empirical models of the ionosphere are considered.

Dispersion of forward and backward (dissipative) magnetostatic surface waves is analyzed in the geometry of a plane-parallel in-plane magnetized ferrite plate with dissipation. The results of calculation of dispersion curves and characteristics of the group velocity as a function of the real and imaginary parts of the wave number are presented. A limitation on the dispersion curves and the group velocity with respect to the maximum value of the wave number has been revealed and interpreted on the basis of the aperiodic propagation mode. Practical recommendations for lowering of this limitation are given.

The results of the calculation of the electrodynamic parameters and of the structural optimization of an in-phase-mode double-gap cavity for a W-band klystron with a strip electron flow are presented. The effect of the dimensions of the drift space on the characteristic impedance and interaction coefficient is investigated, and the conditions for obtaining a uniform distribution of the longitudinal component of the electric field over the width of the drift space are determined.

One-dimensional flows of charged particles with opposite charge signs moving in the same direction are investigated, including an electron diode (or a diode with negative ions) shot by positive ions and an ion diode pierced by relativistic electrons. Variants with different degrees of space charge compensation at the diode output and the case of full charge, current, and magnetic-field (electromagnetic) compensation are discussed.

The problems of designing stripline and microstrip bandpass filters with mixed coupling, including the magnetic and electric components of the interaction, are considered. It is shown that the transmission zeros corresponding to mixed coupling coefficients can be shifted along the frequency axis by changing the shape of the stepped-impedance resonators. It is confirmed that N-resonator planar filters can have (N–1) transmission zeros. Designs of microstrip filters with combined coupling, which include mixed coupling and the traditionally used magnetic and electric coupling, are proposed. It is shown that the number of transmission zeros of such filters is smaller than for filters with only mixed coupling, but their designing and tuning are less labor-consuming. The data of the experiment and computer simulation are presented.

A simple analytical approximation for computing radio images of 3D objects is proposed for an airborne MIMO-type holographic in-plane surveillance radar systems (PSRSs). The model is intended for realtime estimation of the quality of 3D images in such PSRSs during selection of the main parameters of the MIMO antenna system, the frequency band, and the bandwidth of the sounding signal. The results can also be applied to conventional PSRSs, a factor that makes it possible to perform a comparative analysis of PSRS versions and select the PSRS embodiment.

A number of algorithms for image filtering based on the geodetic distance kernel have been proposed recently. When applied to noisy images, some of them yield restoration results that are comparable to those provided by the best modern algorithms. An algorithm of this class that improves the restoration result for multispectral images is proposed. The algorithm uses a convolution kernel based on the geodetic distance and offers a number of advantages, since it allows for recursive computation and, consequently, rapid image processing. The quality of image restoration by the proposed algorithm increases as a function of the number of image channels, which is important for restoration of multispectral images. Several criteria are used to estimate the quality of image restoration.

This study is devoted to the analysis of algorithms of calculating the fast Hough transform for two- and three-dimensional images. A method for calculating the fast Hough transform (FHT) for straight lines in a three-dimensional image is proposed; its space and time complexity are Θ(n⁴), where n is the characteristic linear size of the input image. The FHT algorithms for approximation in two- and three-dimensional spaces are considered, and properties of the accuracy and completeness of the corresponding sets of dyadic patterns are investigated.

The causes of the appearance of distortions in the image formation and the approaches to correction of these distortions are considered. The motion blur, optical aberrations, and atmospheric scattering are used as distortion models. The applicability of metrical and topological characteristics of the distorted signal in distortion diagnostics and image restoration is examined.

The purpose of this work is to estimate target coordinates and velocity. Target tracking is performed by an autonomous underwater vehicle (AUV). The observer is equipped with the direction finder that measures the azimuth and elevation angles of the target and the target range. Such problems are normally solved with the aid of non-linear filters due to nonlinearity of measurements. However, most filters produce estimations with unknown bias in the absence of estimations of accuracy. An important problem is related to unobservability of the target. A pseudomeasurement method is proposed to transform the problem of estimation into a linear problem. Such an approach makes possible to estimate coordinates and velocity of a moving target and solve the problem of unobservability. Results of computer simulation prove efficiency of the proposed algorithm in the problem of passive target tracking when only angles are measured.

The paper is devoted to the promising bin packing problems and some applications. A system view on the formulation of problems based on a set of elements (objects), a set of containers, and binary relations over the specified sets (precedence, dominance, and correspondence of elements to containers) is suggested. Special versions of packing problems with estimations of elements (objects) based on multisets are described. Examples in communication networks, such as the choice of information messages and two-dimensional packaging of messages in WiMAX systems are also briefly considered.

An approach to organization of a system for automatic earthquake prediction is developed. This approach is not bound to any particular type of data, and all data on seismotectonic processes are displayed using the spatial and space-time fields. The prediction field is learned from the feature fields and the sample of predicted earthquakes. The learning method proposed here is the least alarm method. The results of modeling of earthquake prediction for the regions of Japan and Mediterranean are presented. Modeling implied the analysis of prediction fields reflecting stationary and dynamic properties of the seismic process. The results of modeling demonstrate the efficiency of application of the least alarm method to earthquake prediction.