1. Absorption of electromagnetic energy of dipole antenna of double layer dielectric sphere
wave absorption, double layer dielectric sphere, perfectly conducting spherical screen, radial dielectric dipole, dual series equations, method of analytical regularization
Vestnik KhNU ¹712 Pages. 62-66
Considered the problem of electromagnetic energy absorption by double layer sphere, which the simplified model of human head protected by the helmet with the dipole antenna. This investigation is interesting due to control of energy absorption in sensible parts of human head tissues. The problem is solved by method analytical regularization, which reduces the problem to the system of linear equations of Fredholm second kind which provides guaranteed convergence. Basic absorption characteristics are obtained and comparison of protection effectiveness for different sizes helmets are made
2. SCATTERING AMLITUDE ERROR ESTIMATION FOR MOMENT'S METHOD IN L2 FOR 2-D SCREENS
A.G. Tyzhnenko, Y.V. Ryeznik
testing, reference solution, moment's method, 2-D screens
Vestnik KhNU ¹756 Pages. 65-70
The scattering amplitude error estimation problem for practically used MoM solutions in L2 function space for scattering from 2-D screens is addressed. To this end, a rigorous Galerkin solution in L2 to logarithmically singular and hypersingular EFIE is used as a reference solution for scattering amplitude error estimation by benchmarking. This one requires substantially lower computational efforts than using of the same MoM algorithm but with very high mesh density as a reference solution. To many, the approach helps to avoid unpredictable errors due to the ill-conditioning connected with high mesh density for any MoM solution to the EFIE in L2. Using the approach, the asymptotic decay rate of scattering amplitude error is investigated for some MoM algorithms widely used in practice
3. The Gaussian beam scattering on the bounded sequence of alternate grates of dielectric bars
V.B. Kazanskiy, V.R. Tuz, D.V. Yudintsev
Gaussian beam, thick grate of dielectric bars, anisotropic layer, periodic structure
Vestnik KhNU ¹756 Pages. 83-86
The Gaussian beam scattering on bounded periodical sequence of thick grates of dielectric bars are investigated. Identification of discrete structure with appropriate thickness homogeneous anisotropic layer was carried out for define sequence basic element transmission matrix. The sequence scattering coefficients were written down via Mougin polynomials. The effects of form distortion, beam splitting into several beams, side shift of beam axe were shown. Their correlation with scattering coefficients phase and module angle dependence of separate grates was established.
4. Arbitrary falling of wave on grate with by ànisotropic layer
A.I.Adonina, R.R.Naumov, A.I.Sljusarev
grate, magnetodielectric, stream of power, method of Riman-Gilbert, anisotropic, resonator
Vestnik KhNU ¹806 Pages. 22-28
A decision set the problem is conducted for Å and Í pour, proper two subsystems into which the system of equalizations of Maxwell is divided for anisotropic environments. The mixed field (in the case of the arbitrary falling of wave) is determined as a sum of two types pour. Integral descriptions are from the decision of the reduced endless systems of linear algebraic equalizations, got the method of task of Riman-Gilbert. The analysis of the graphs, partly resulted in work, allows to set influencing of parameters of structure and angles of incidence of wave on an anomaly in the dissipated field for every concrete case, and also to suppose and to confirm physical reasons of existence of anomalies a numeral account, as resonances of own waves in the opened resonator which is design the explored structure.
5. Way of transformation of the patterns of reception antennas
A.A. Sorokin, A.F Sorokin, O.V. Sokolova, R.N. Zaluzhniy, N.N. Gorobets
miñrowaves, antennas, pattern, Frenel zones
Vestnik KhNU ¹806 Pages. 29-32
the expedient of management by the shape of directional diagrams with the help of a fragmentation of Frenel zones is offered. Measuring the shape of a pattern diagram of the horn and spiral antennas are carried out. Peak allocations a builder of a field in short-range, medial and long-range bands for different frequency range are received and analyzed. By results of experiments intensity, a corner, radius for long-range and short-range bands is constructed 3D images.
6. Identification and localization of radar impulses buried in noise
A. G. Tyzhnenko, Y. V. Ryeznik
radar, pulse, identification, localization, low SNR
Vestnik KhNU ¹806 Pages. 70-74
Statistical method identification and localization of radar impulses buried in noise is addressed. To this end, the correlation coefficient between carrier samples measured in the extremal points and analogous set of points of received signal is proposed to implement. Such measurements for receiving signal need to be done at least by one tenth of the half period of the carrier. Because of very simple algorithm proposed, such measurements do not lead to heavy computational burden. To decrease identification and localization errors for given signal to noise ratio (SNR) one needs to increase the number of measurements points, and hence, the pulse width. To prevent this issue, one can increase the carrier frequency. In general, the method accuracy increases with the carrier frequency. The method proposed permits theoretically to identify with fidelity impulses buried in noise for SNR lower than -30 dB.
7. Potentially unbreacable ciphering on a hybrid physical-mathematical level
A. G. Tyzhnenko, E. V. Ryeznik
bit, stochastic signals, safe communication, hard drive protection
Vestnik KhNU ¹834 Pages. 108-113
A new kind of ciphering based on stochastic representation of bits as series of samples is addressed. Stochastic comparison is used for bit identification. Security level is increased by adding noise samples to signal samples and mixing signal samples with noise samples within one signal packet. The signal packet length and distribution features of signal samples among noise samples in signal packets are unique for given communication line, as well as stochastic representation of bits (0s and 1s). Using of noise in signal packets leads to enormous large computation in decrypting process which is unrealistically to do regardless what computer system is used. More to the point, the unique features of communication line mentioned above can be changed for each message that prevents information leakage in the case of stealing these ones in any previous period. Impossibility of decrypting by any reasonable time period of any message eavesdropped by a cryptanalyst guarantees the confidence of information which has permanent importance
8. Potential of a spherical segment which is placed within a spherical layer with circular aperture.
electrostatics, spherical segment, layer, Fredholm integral equation
Vestnik KhNU ¹834 Pages. 120-126
The rigorous solution of an axially symmetrical electrostatics problem is obtained. The potential of an ideal spherical segment, which is placed within a spherical layer with circular aperture, is analyzed. We use the methods of regularization, separation and inversion of summarized equations, the method of residues in singular points of analytical functions, the methods of contour integrals and integral transformations. Fredholm integral equation of the second kind with a compact operator in Hilbert space L2 is obtained. The comparison with known results and limit variants is given. The effectiveness of the constructed algorithm is confirmed. Some generalizations of the problems are considered
9. Arbitrary falling of wave on grate with by a screen and layer of environment
A.I.Adonina, R.R. Naumov, A.I.Sljusarev
grate, magnetodielectric, stream of power, method of Riman-Gilbert, resonator
Vestnik KhNU ¹853 Pages. 45-50
A decision of the set problem is conducted in the exact raising without imposition of limits on the parameters of structure, angles of incidence of wave, wave-length, parameters of environment. The variant of method of Riman-Gilbert was used for the case of the arbitrary falling of wave. A vectorial task is presented as a sum of two scalar tasks, proper subsystems into which the system of equalizations of Maxwell is divided for Å- and Í-fields. A numeral account, resulted in work as the graphs, confirms assumption about physical reasons of existence of anomalies, as resonances between active spectral accordions and own waves of the opened resonator which designs the explored structure
10. Diffraction of the plane acoustic wave on the hard spherical segment, shielding of the ball
acoustics, spherical segment, shielding ball, resonance frequencies, algebraic equations of the second kind
Vestnik KhNU ¹853 Pages. 57-63
A solution of the axisymmetrical problem of acoustics in strict formulation is built. The acoustic potential of the velocity of the plane wave, diffracted on the hard spherical circular segment, shielding of the ball is analyzed. The method of regularization of the paired summarized equations is used. The method of the integral transformations is applied. The principal part of the summarized equations is isolated and inverted. The effectively solvable system of the linear algebraic equations of the second kind with the compact operator in the Hilbert space l2 is obtained. Comparison with the known results and limited cases of the problem is given. The effectiveness of the constructed algorithm is confirmed. Some resonance frequencies and generalization of the task are examined
11. New statistical methods of recognition and classification for automatic interpretation of remote observations
Koltunov Y.A., Dumin O.M., Katrich V.A., Naumov R.R.
methods of recognition and classification, blenderized models of the probabilistic distributing, teaching selection
Vestnik KhNU ¹966 Pages. 37-49
Mathematical models, computational algorithms, and also prospects of development and application of three new methods of recognition and classification (RÀC), namely, construction of distinctive characteristics of objects; classification on the basis of probabilistic teaching selection with optimization of method RAC; account of dynamics of features of recognized objects are presented in the article. Recognition and classification is an area of modern science that have a boundless list of applications in all spheres of human activity. From the list of applications the only one is selected in the present work, but the most actual one, that is the remote sensing of ground surface in radiofrequency band with the purpose of study and maintainance of natural resources of Earth.
founded: 11 result (s)