Kharkov National University
V.N.Karazin
Main / Vestnik KhNU /Radiophysics and Electronics
 
Main
 
Edit. Board
 
For authors
 
Numbers
 
Authors
 
Titles
 
Keywords
 

1.  DESTRUCTION OF PULSE TRAINS IN WEAKLY NONLINEAR OSCILLATOR
D.D. Vavriv
chaos, dynamical systems, train pulses, quasi linear oscillator
Vestnik KhNU 756 Pages. 71-78

A study has been carried out on the transition of train of pulses via a weakly nonlinear oscillator. Conditions of destruction of such trains as a result of appearance of chaotic instabilities have been analyzed. Analytically conditions of the appearance of chaotic instabilities have been determined by using the method of secondary averaging.



2.  Determena Frequency properties of intervalley electron transfer in AlN
V. T. Plaksiy, .V.Arhipov, . S. Tischenko, . . Kamishanova, E.D. Prokhorov, .V.Dyadchenko, D. P.Chueshkov
perfect crystal, zone overcrystallization, temperature gradient
Vestnik KhNU 966 Pages. 19-22

The problem of growing of perfect bismuth-antimony monocrystals having of a uniform distribution of Sb atoms through the crystal by help floating-zone refining method is considered. The expression for temperature gradient in melt and temperature distribution for any melt point have been obtained. The monocrystals growing maximal velocity have been estimated. The growing velocity must be lower then 1 mm per hour was showed. It is velocity not lead to concentration overcooling and arising inhomogeneous dendrite structure. For solution with certain composition ( at = const) overcooling may be eliminated by either increasing of temperature gradient in liquid faze or decreasing growing velocity are showed.


Download >>


3.  Determination of optimal parameters of a magnetocardiographic hexagonal measuring grid
A.Yu. Kostiev, A.Yu. Butrym, S.N. Shulga
magnetocardiography, gradiometer, current dipole, sensitivity, Hessian
Vestnik KhNU 883 Pages. 25-29

The article considers hexagonal grid of gradiometer sensors of magnetic field. The aim of the study is to determine the optimal parameters of the grid and the gradiometers in order to obtain maximum sensitivity of the measuring system in terms of location


Download >>


4.  Dielectric permittivity profile reconstruction by frequency probing problem for a plane-layered media with regard to dispersion
Batrakov D.O., Simachov O.A.
plane layered media, dispersion, inverse problem, dielectric permittivity
Vestnik KhNU 883 Pages. 45-49

In the present paper the problem of dielectric permittivity profile reconstruction with regard to dispersion is discussed. The nature of dispersion function is assumed to be known and unknown functions are real and imaginary parts of dielectric permittivi


Download >>


5.  Diffraction of the plane acoustic wave on the hard spherical segment, shielding of the ball
Rezunenko V.A.
acoustics, spherical segment, shielding ball, resonance frequencies, algebraic equations of the second kind
Vestnik KhNU 853 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


Download >>


6.  Directed and polarization characteristics of the aperture of the circular waveguide with impedance flange
N.N. Gorobets, V.M. Dakhov, I.V. Gorbach
microwave, antennas, waveguides, polarization, pattern
Vestnik KhNU 806 Pages. 3-7

The amplitude and polarization patterns of the radiator in the form of the aperture of circular waveguide with impedance flange, excited by the dominant wave, have been measured by the method of the indicator antenna with polarization plane rotation. It is shown that such radiators have an axial-symmetric pattern, a wide polarization pattern and a low level of side lobes.


Download >>


7.  Directivity characteristics of rarefied antenna arrays
N.N. Gorobets, A.A. Bulgakova
electromagnetic waves, antennas, antenna array, directivity characteristics
Vestnik KhNU 834 Pages. 89-94

The radiation pattern, directive gain and scattering coefficient of equivedistance linear array were calculated and their dependencies on the number of radiators and distances between them were analyzed. It is shown that for every number of radiators the optimal antenna length of L≈0,9(N-1), allowing to obtain the maximum of directive gain, occurs. For greater antenna length or increase in operating frequency, directive gain varies according to oscillating dependencies. The greater number of radiators occurs, the greater difference of maximums and minimums occurs. For small number of radiators (N≤8), the directivity characteristics of the array is higher, then for continuous antennas of the same electrical length. For N≥16, their characteristics coincide


Download >>


8.  Dispersive characteristics of magnetoplasma waves in the rectangular wave guide with InSb
O.A. Zamuraev, O.O. Puzanov, A.S. Tishchenko
magneto-plasma wave, semiconductor plasma, dispersive characteristics, nitric temperature
Vestnik KhNU 834 Pages. 3-7

Frequency dependence of characteristics of magnetoplasma waves in the rectangular wave guide, containing longitudinal and cross-section - magnetized the semiconductor at various sizes of an induction of a magnetic field is experimentally investigated. Areas of values of an induction in which the behavior of wave number and factor of attenuation has resonant character are determined. An existence of two superficial magnetoplasma waves which are distributed in opposite directions is experimentally confirmed in longitudinal - magnetized semiconductor plasma. Good concurrence of results of experiment and numerical calculations is shown


Download >>

founded: 8 result (s)
Development wip.com.ua - V.N. Karazin Kharkov National university