1. Capacitancevoltage measurements in selectively doped ALGAAS/GAAS heterostructures N.B.Gorev, I.F. Kodzhespirova, E.N. Privalov gallium arsenide, selectively doped heterostructures, Schottky barrier, barrier capacitance, capacitance–voltage measurements Vestnik KhNU ¹853 Pages. 37
The dependence of the measured apparent capacitance of selectively doped AlGaAs/GaAs heterostructures on the amplitude of the measuring ac voltage is calculated numerically. An expression that gives the measured apparent capacitance as a function of the true capacitance and the above amplitude is derived. Using this expression and the results of the above numerical calculation, it is shown that capacitance–voltage characteristics of selectively doped AlGaAs/GaAs heterostructures, which feature steeply dropping regions, may be measured at moderately small amplitudes of the measuring ac voltage (of the order of 100 mV) at the expense of taking measurements at two different amplitudes
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2. Global Sensitivity analysis of the dipole matrix element according to variation of parameters of the indium surface segregation in ingan/gan quantum well M.V. Klymenko indium surface segregation, semiconductor nitrides, piezoelectric polarization, dipole matrix element, global sensitivity analysis Vestnik KhNU ¹853 Pages. 814
In this paper, influence of the indium surface segregation on dipole matrix element for InGaN/GaN heterostructure is under investigation. The global sensitivity analysis has been applied for quantitative estimation of the indium surface segregation effect at each interface of the quantum well. Together with the indium surface segregation, the piezoelectric effects are considered. It has been shown that joint action of the piezoelectric fields and the indium surface segregation leads to changes in the selection rules for optical transitions. Results give the method to apply the optical spectroscopy for observation of the indium surface segregation
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3. Oscillation efficiency of TED diodes on the basis of nitrides E. D. Prokhorov, O. V. Botsula, A. N. Zabazhan AlN, GaN, InNdiodes, drift speed, oscillation efficiency Vestnik KhNU ¹853 Pages. 1521
Oscillation efficiency of intervalley transfer electrons diodes on the basis of nitrides (InN, GaN, AlN) is considered. Electric fields at peak oscillation efficiency are determined. The results have been compared to results for GaAs. The account of floatable potential in connections InGaN improves their power characteristics in comparison with power characteristics of these connections without taking into account floatable potential, maximal efficiency In_{0.8 }Ga _{0.2N and In0.5Ga0.5N diodes to compare to InN diodes on 30 % is higher (22 % to compare to 16,43 %) but at more high tensions of an electric field. The maximal oscillation efficiency is observed at higher electric fields than GaAs ( from 250 êV/sm for InN to 1000 kV/sm for AlN)}
4. Inner partial mutual admittance of two overlopping longitudinal slots in a rectangular waveguide with dielectric layer parallel to narrow walls A.A.Lyakhovsky, L.P.Yatsuk, A.F.Lyakhovsky , layer, dielectric, slot, admittance, scattering parameters Vestnik KhNU ¹853 Pages. 2227
The expression for the partial inner mutual admittance of two longitudinal slots overlapping along waveguide longitudinal axis is obtained. The slots are cut in a broad wall of a rectangular waveguide filled with threelayered dielectric. The excitation problem is solved with the modified eigen waves method. As eigen waves of the LE and LM modes are chosen. The field in the source region includes the potential functions as well. Dependences of inner mutual admittance and scattering parameters on distance between two slots and frequency are investigated. The system scattering parameters calculated are in a good agreement with experimental data
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5. Influence of apertureillumination law on nearfield characteristics of aperture antennas E.E. Ovsyannikova, A.V. Shishkova, N.N. Gorobets electromagnetic waves, reactive fields, aperture radiators, Kirchhoff technique, nearfield, farfield, amplitude distributions, phase characteristics, amplitude characteristics, reactive radiation power Vestnik KhNU ¹853 Pages. 2836
On the basis of Hertz potentials the investigation of nearfield reactive region of square aperture antennas with various aperture illumination laws has been carried out. The influence of the field amplitude distribution law in the aperture on the extension of this region has been studied. The calculation and analysis of amplitude, phase and power radiation characteristics, including reactive radiation power density, at the different planes in nearfield region have been carried out. The analysis of the criteria for estimation of nearfield reactive region boundary has been carried out
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6. Algorithms of the processing signal from the trellised receiver for measuring of the laser radiation characteristics Kokodiy N.G., Pak A.O. the laser, optical radiation, intensity, bolometer, direct task, reverse task Vestnik KhNU ¹853 Pages. 3744
In this paper has been considered the development of the device for the measurement of the intensity distribution in the beam of optical radiation. The algorithm of processing of a signal from the receiver of radiation is studied. The method of measurement of the intensity distribution of optical radiation by the bolometric grid is offered. The developed algorithms for processing a signal from the measuring converter and programs realizing them are checked up experimentally, their serviceability is confirmed. The comparative characteristic of algorithms based on the transformation of Fourier and transformation of Radon has shown an opportunity of their use in practice
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7. 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 RimanGilbert, resonator Vestnik KhNU ¹853 Pages. 4550
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, wavelength, parameters of environment. The variant of method of RimanGilbert 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 Ífields. 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
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8. Single cone with longitudinal slots excitation by an impulse point source A.V. Artyukh, y.A. Doroshenko, Y.D. Shimuk impulse source, cone, longitudinal slots, analytical solution, numerical solution Vestnik KhNU ¹853 Pages. 5156
In this work the excitation of a semiinfinite perfectly conducting cone with periodic longitudinal slots by an impulse radial source problem is investigated. The solution of the wellposed initialboundary problem is found using an analytically numerical method based upon Green function and MelerFock integral transforms applying. It is shown that the original electrodynamic problem is equivalent to the one of the Fredholm linear algebraic equations system of the second kind solving. Analytical view of the solution is derived and the graphs illustrating the field dependence on the aperture angle and angle slot width are presented
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9. 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 ¹853 Pages. 5763
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 l_{2} 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
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10. Asymptotic method of the solution of diffraction problem on the convex impedance cylinder, excited by the string of the electric current V.I. Vyunnik, A.A, Zvyagintsev diffraction, asymptotic method, interpolation, convex impedance cilinder Vestnik KhNU ¹853 Pages. 6470
In the work considered the problem of diffraction electromagnetic waves on the convex impedance cylinder exited by string of the electric current, located near to its surface. The method asymptotic theories of the diffraction, offered by Fok is used. Are received asymptotic interpolation formulas for calculation radar cross section of the system string the current  cylinder, for a case of circular and elliptic impedance cylinders. The received formulas are suitable for calculations both in shadow and in lighted areas. It is shown, that these formulas can be distributed on a case of the any convex impedance cylinder with variable curvature
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11. Algorithm of a pulse signals delay definition, based on a Hilbert's transformation D.O. Batrakov, D.V.Golovin, S.V. Grekov, A.G. Batrakova* pulse signals, definition of a delay of signals, Hilbert's transformation, planelayered media, thickness measurements Vestnik KhNU ¹853 Pages. 7176
In the present paper the algorithm of processing of the pulse signals reflected from planelayered media is offered. It is supposed, that an effective thickness of layers less than spatial size of an impulse. This feature of a problem complicates use earlier proposed methods of signals time delay evaluating. Therefore in paper the theoretical analysis of possibilities of various approaches for processing of signals is carried out and the algorithm and the corresponding software for definition not only a time delay, but also physical and geometrical characteristics of investigated objects are offered. Results of numerical modelling and experimental researches for the purpose of definition of sensitivity and resolution of a method, and also possibility of its practical use are given
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12. Theoretical investigation of photonic crystals by means of analysis of photonic density of states maps I.V. Guryev photonic crystal, photonic density of states, transmittance spectrum, plane wave expansion method, finite differences method Vestnik KhNU ¹853 Pages. 7783
In the work, there have been computed the photonic density of states maps of the 2D photonic crystal by means of plane waves expansion method by the analogy with photonic band gap maps. The photonic density of states maps allows precise determination of the parameters of photonic crystals during the design process of the photonic crystalbased device. Moreover, there have been carried out the comparison with analogous characteristics obtained by the finite differences time domain method. Comparison results indicate the similarity of results obtained by two methods, however, the computation of photonic density of states maps requires much less time at the same computation precision. Moreover, in the work there have been carried out the comparison between the efficiencies of the photonic density of sates maps and the photonic band gap maps analysis methods
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13. Paramagnetic properties of ASO2" free radical in irradiated KDP single crystals A.N. Levchenko KDP single crystal, ionizing irradiation, free radicals, EPR, spin Hamiltonian Vestnik KhNU ¹853 Pages. 8487
The electron paramagnetic resonance (EPR) spectra of AsO_{2}^{2} free radical in potassium dihydrogen phosphate (KDP) single crystals irradiated with gamma rays and electrons have been investigated. The angular dependences of the spectra have been measured. The number of magnetically inequivalent sites for the AsO_{2}^{2} in the crystal lattice of KDP has been determined. The principal values of gfactor and hyperfine structure tensor have been calculated. It is found that the radical exhibits orthorhombic symmetry. The lagest component of hyperfine tensor is in the ab crystal plane. The molecular planes of the free radicals and the ab crystal plane are mutually perpenducular. The superhyperfine structure of the spectra indicates an existence of two protons near the paramagnetic center
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14. HF ionosonde signal focusing by traveling ionospheric disturbances Yu. B. Milovanov, V. F. Pushin, O. F. Tyrnov traveling ionospheric disturbances, signal amplitude variations, Doppler frequency shift, focusing factor, computer simulation Vestnik KhNU ¹853 Pages. 8894
HF signal focusing due to linear and nonlinear wave disturbances occurring during monostatic ionospheric sounding is discussed. A technique is developed for estimating signal amplitude variation due to focusing based on beating amplitude measurements during significant Doppler frequency shift events. The intercomparison of measured and modeled variations in beating amplitudes, the focusing index, and Doppler frequency shift show a qualitative agreement. The simultaneous analysis of variations in the beating amplitude and the Doppler frequency shift makes the interpretation of measurements more definite, e.g., it permits the isolation of large scale disturbances traveling at approximately 1 km/s
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15. Random inhomogeneous liquid medium as a continuous laser of lowintensity modulator for excitating sound in the medium B. G. Yemets laser, random inhomogeneous liquid medium, interference, temperature field, optical acoustical phenomenon, sound, excitation, modulation Vestnik KhNU ¹853 Pages. 95100
When a medium is irradiated by laser pulses, sound waves are excited in this medium, i.e., the wellknown optical acoustical phenomenon occurs. To excite sound oscillations, the specific laser beam modulator is shown to be unnecessary. The role of the modulator can play the liquid itself, which is a random inhomogeneous medium. The real liquid contains suspended solids and gas bubbles of small dimensions (dust particles and the like) that move irregularly in space (fluctuations). As a result, the electromagnetic wave interference taking place in the liquid undergoes random changes. Consequently, the temperature field changes, and hence variations in the local pressure occurs (thermooptical mechanism for exciting sound). The excitation of sound due to the laser irradiation of low intensity is observed in an increase in the gas bubbles dimensions in the liquid
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