Efficiency of integral phase approximation of light beams in adaptive focusing systems
Efficiency of integral phase approximation of light beams in adaptive focusing systems
F.Yu. Kanev, E.A. Lipunov, S.S. Chesnokov
Algorithms of reproduction of a specified phase profile of a light beam by an elastic mirror have been considered. An effective procedure of phase approximation has been proposed based on the method of least squares and allowing the first- and second-order phase surfaces to be specified with a high accuracy using a small number of control channels. The effect of the phase corrector parameters on the quality of adaptive focusing in linear and nonlinear media has been analyzed on the basis of a numerical model of the adaptive mirror.
Show AbstractOptimization of resonators in solid-state ring lasers with end pumping
Optimization of resonators in solid-state ring lasers with end pumping
V.V. Dedysh, V.E. Nadtotcheev, O.E. Nanii
A solution has been found to the problem of selecting optimum parameters of the resonator and the pumped region in a solid-state ring laser with monochromatic end pumping with allowance for a non-uniform amplification and also for the astigmatism of the mirrors and other components of the resonator. It is demonstrated that the minimum lasing thresholds can be achieved through the use of resonators which are equivalent to a concentric resonator, with compensation for the mirrors' astigmatism. A method for calculating the optimum size of the pumped region is given.
Show AbstractAcoustic diffraction tomography of boundary scatterers
Acoustic diffraction tomography of boundary scatterers
V.A. Burov, A.V. Glazkov, I.P. Prudnikov, O.D. Rumyantseva, E.Ya. Tagunov
An approach to the solution of tomographic inverse problem of scattering by boundary acoustic inhomogeneities is briefly described using the extrapolated Richardson method. Results of the experimental verification of the theory that has been developed are presented.
Show AbstractOn destruction and dissipation of long waves on a shelf
On destruction and dissipation of long waves on a shelf
S.A. Arsenyev, A.Yu. Gubar', N.K. Shelkovnikov
The paper considers the problems of calculating nonlinear processes of harmonics boosting, front steepening, and destruction of a long monochromatic wave (with the formation of a shock wave) moving over a shallow-water plane shelf. The well-known theoretical method of simple waves is generalized to include the dissipation due to friction against the bottom. The destruction conditions are found, and the growth of harmonics in a tidal wave M2 propagating on the Siberian shelf is calculated.
Show AbstractGlobular cluster M15: effects of gravitational focusing
Globular cluster M15: effects of gravitational focusing
M.Yu. Maslakov
The central part of the stellar globular cluster M15 has been investigated in search of the effects of gravitational focusing. The feasibility of this effect has been established by comparing the dispersion of the brightness of stars in the central part of the cluster, where this process more probable is, with the brightness of stars in a region distant from the center. The magnitudes of the dispersions have been estimated by the maximum likelihood method.
Show AbstractStability of orbits of small planets in the outer part of the asteroid ring
Stability of orbits of small planets in the outer part of the asteroid ring
I.A. Gerasimov, N.V. Rakitina
In the framework of the limited planar circular three-body problem it is shown that asteroids, which are unstable according to Hill, nevertheless can have stable orbits in the case of the first-order resonances. The limits and periods of changes in the eccentricities have been calculated for asteroids of the Hilda group.
Show AbstractOn the correlation between the width of the phase transition region near the Curie point and the variance of distribution of hyperfine magnetic fields in alloys $Fe_{75}(Cr_xCo_{1-x})_{25}$
On the correlation between the width of the phase transition region near the Curie point and the variance of distribution of hyperfine magnetic fields in alloys $Fe_{75}(Cr_xCo_{1-x})_{25}$
P.N. Stetsenko, M.A. Mostafa (Egypt), S.D. Antipov, L.A. Kondrashova
A correlation between the width of the phase transition region near the Curie points and the variance of the distribution function for hyperfine magnetic fields has been established on the basis of studies of the temperature dependence of magnetization and the distribution function of hyperfine magnetic fields on $^{57}Fe$ nuclei in rapidly quenched $Fe_{75}(Cr_xCo_{1-x})_{25}$ alloys.
Show AbstractOptical properties of magnetic semiconductors $xCuCr_2S_4- (1-x)Cu_{0,5}Ga_{0,5}Cr_2S_4$
Optical properties of magnetic semiconductors $xCuCr_2S_4- (1-x)Cu_{0,5}Ga_{0,5}Cr_2S_4$
L.I. Koroleva, Sh.Z. Sadykova, V.Yu. Pavlov
The spectra of diffuse reflectivity of magnetic semiconductors $xCuCr_2S_4-(1-x)Cu_{0,5}Ga_{0,5}Cr_2S_4$ ($x$ = 0; 0.05; 0.1) have been investigated within the temperature range from 115 to 353 K. Based on the spectra obtained, a diagram of the energy band structure is proposed for these semiconductors, which is close to the band structure of a similar compound, $xCuCr_2S_4-(1-x)Cu_{0,5}In_{0,5}Cr_2S_4$.
Show AbstractLow-temperature relaxation in disordered organic semiconductors
Low-temperature relaxation in disordered organic semiconductors
I.P. Zvyagin, A.V. Plyukhin
The electron hopping relaxation in disordered organic semiconductors was analyzed within the framework of the diagonal-disorder model. The time variation of the electron concentration at the percolation level was found for different relaxation stages, the conditions for passing from dispersive to normal (Gaussian) transport were studied, and the dependence of the dispersion parameter on the temperature and the disorder degree was determined.
Show AbstractRenormalizable model of massive gauge fields in a five-dimensional space
Renormalizable model of massive gauge fields in a five-dimensional space
D.A. Slavnov
A new scheme is proposed for the description of massive gauge fields in which masses are induced by additional components of vector fields. By way of example, the scheme was applied to the gauge sector of the model of weak electric interactions.
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