Faculty of Physics
M.V.Lomonosov Moscow State University
Menu
Найдено: 1254

Dynamics of a multilayer adaptive network with cooperative interaction between layers

Dynamics of a multilayer adaptive network with cooperative interaction between layers

D. V. Kirsanov$^1$, V. V. Makarov$^1$, M. V. Goremyko$^1$, V. O. Nedajvozov$^1$, A. E. Hramov$^1$

Memoirs of the Faculty of Physics 2017. N 6.

In this paper, we investigated the processes of synchronization and the formation of structural patterns in a multilayered network of dynamic elements. The layers compete for an optimal topology, where elements interactions within the layer occurs according to the principles of additivity and homeostasis.

Show Abstract

Formation of clusters in a complex network reflecting the process of cooperation in social groups

Formation of clusters in a complex network reflecting the process of cooperation in social groups

V. O. Nedajvozov$^1$, V. V. Makarov$^1$, M. V. Goremyko$^1$, D. V. Kirsanov$^1$

Memoirs of the Faculty of Physics 2017. N 6.

In this study, we investigated the processes of clustering in multilayered social networks of collaborations and professional interactions. We have identified the basic principles that are responsible for the interconnection of topology and dynamic characteristics in such kind of networks.

Show Abstract

Calculation of high-efficiency resonators of solid-state lasers

Calculation of high-efficiency resonators of solid-state lasers

P. A. Nosov

Memoirs of the Faculty of Physics 2017. N 6.

The problem of calculating the stable resonators of solid-state lasers forming a Gaussian beam with variable spatial parameters (waist diameter, confocal parameter, angular divergence) with the energy parameters of the radiation unchanged is considered. The scheme of the optical system of a resonator of a solid-state laser to solve this task is presented. By the ray bundle method and on the base of scalar diffraction theory, the problem of calculating the characteristics of a laser beam formed by linear resonators of arbitrary configuration taking into account the aberrations of its elements is considered. The results of modeling the mirror-lens resonator scheme for varying the spatial parameters of the output beam by the ray bundle method are presented. For stable resonators approximate analytical expressions are obtained, which allow to calculate the distribution of the complex amplitude on mirrors and in an arbitrary cross section of the resonator, the spatial parameters of beam and the frequency spectrum of the radiation for a rectangular and circular aperture of mirrors. The configurations of resonators in which the aberrations of the shape of the surface of mirrors have a significant effect on the characteristics of the formed laser radiation are determined.

Show Abstract

Calculation of the optical system for process equipment on the basis of high-power fiber laser

Calculation of the optical system for process equipment on the basis of high-power fiber laser

P. A. Nosov, А. O. Shchadko

Memoirs of the Faculty of Physics 2017. N 6.

Features of functioning of optical systems of the process equipment on the basis of powerful fiber lasers are considered. The experimental results show that the distribution of the power density of the laser radiation and the temperature distribution on the optical element of the laser head can be approximated by the Gaussian function. The results of experimental studies of the heating of optical elements from high-purity quartz glass of the Russian production of the grade KS-4V are presented in the formation of radiation from a CW high-power fiber laser. The maximum heating temperature of optical elements at various laser power densities are determined. Expressions are given for analyzing the thermal-optical distortions of the beam at the output of the optical system of laser equipment for technological processes of material processing. Analysis of the optical systems calculated has shown that when heating of lenses made of quartz glass under the influence of high-power laser radiation, the output waist is shifted closer to the protective glass, and its diameter remains practically unchanged. The researches show that when designing of laser optics for the modern technological equipment on the basis of powerful fiber lasers the account of heating of lenses is very important.

Show Abstract

The temperature dependence features of the spectral characteristic of a diode laser with a frequency doubler

The temperature dependence features of the spectral characteristic of a diode laser with a frequency doubler

V. V. Bliznyuk$^2$, O. I. Koval$^2$, V. P. Alekseevich$^2$, A. G. Rzhanov$^1$, A. E. Tarasov$^2$

Memoirs of the Faculty of Physics 2017. N 6.

It was experimentally found that when the ambient temperature changes from 260 K to 345 K, the peak wavelength of the spectral characteristic of a laser diode with a frequency doubler on a KTP crystal is practically not shifted relative to the position it occupied at room temperature. The justification of this phenomenon is given.

Show Abstract

Methods to improve immunity noise detection and direction finding using a vector-scalar modules

Methods to improve immunity noise detection and direction finding using a vector-scalar modules

G. N. Kuznetsov$^1$, A. F. Kurchanov$^2$

Memoirs of the Faculty of Physics 2017. N 5.

Made direction finding of broadband sources of scalar antenna (SA) and vector-scalar modules (VSM) using processing the flow of power and the new method based on the use of pseudovectors built on the projection of vector vibrational rate (VVV). Investigated method of interference suppression from a local source with using of vector fields.

Show Abstract

Research unidirectional reception, evaluation range and source depth using scalar and vector-scalar antennas

Research unidirectional reception, evaluation range and source depth using scalar and vector-scalar antennas

G. M. Glebova$^1$, G. N. Kuznetsov$^2$

Memoirs of the Faculty of Physics 2017. N 5.

We analyze the spatial spectra at the output of the linear scalar or vector-scalar antenna (SA or VSA) at signal processing methods having a different resolution, consistent or inconsistent with the transfer function of the waveguide. The experiments were conducted in a shallow pool at the stationary location of the antenna and the emitter and in regime of the towing with the moving noise source. VSA, unlike SA, suppresses signals coming on «mirror» petals and has unidirectional direction finding, and at using consistent processing in passive mode uniquely determines the distance and the depth of the source.

Show Abstract

Theoretical analysis of a torque exerted by the vortex ultrasonic beam on the absorber located in liquid

Theoretical analysis of a torque exerted by the vortex ultrasonic beam on the absorber located in liquid

M. E. Terzi, S. A. Tsysar, P. V. Yuldashev, O. A. Sapozhnikov

Memoirs of the Faculty of Physics 2017. N 5.

Waves of any nature carry energy and momentum. In certain configurations of wave beams, angular momentum transfer is also possible: the corresponding beams are called “vortex beams”. In this paper, we study the ability of a vortex acoustic beam of the megahertz range to rotate a large-sized absorber (of several dozen wavelengths in diameter) in a liquid. The vortex beam was formed in water by passing ultrasonic radiation from a focusing piezoceramic source through a non-uniform in thickness 12-sector phase plate made from Plexiglas. The beam propagated vertically upward and was directed to an acoustic absorber in the form of a cylinder 10 cm in diameter and 3 cm in height made of silicone rubber. The absorber was freely suspended on a thin elastic thread. It is demonstrated that when the absorber is irradiated, it is rotated. By scanning the acoustic field in the transverse plane by a miniature hydrophone, two-dimensional distributions of the amplitude and phase of the wave were found, and on the basis of these calculations the moment of the radiation beam force applied to the absorber was calculated. The results of the calculations are in agreement with the observations.

Show Abstract

Ultrasonic gas flowmeters with laid-on sensors

Ultrasonic gas flowmeters with laid-on sensors

A. D. Mansfeld$^1$, A. G. Sanin$^1$, G. P. Volkov$^1$, R. V. Beliaev$^1$, D. V. Moroskin$^2$

Memoirs of the Faculty of Physics 2017. N 5.

Two types of ultrasonic flowmeters with laid-on sensors have been described realizing gas flow measurement through metal pipe wall. The main advantage of developed flowmeters is an ability to measure gas flow without sensor insertion into the wall even at low pressure. Different probing methods (pulse, continuous), "wall" signals influence, useful signal selection methods have been considered. Laboratory and field experimental results are presented.

Show Abstract

3D-printing possibilities for the manufacturing technology development of hydroacoustic longitudinal bending type emitters with the complex radiator's body geometry

3D-printing possibilities for the manufacturing technology development of hydroacoustic longitudinal bending type emitters with the complex radiator's body geometry

A. K. Britenkov$^{1,2}$, B. N. Bogolybov$^1$, S. A. Smirnov$^1$, V. A. Perfilov$^1$

Memoirs of the Faculty of Physics 2017. N 5.

Low-frequency hydroacoustic emitters are being used in a wide range of tasks: from long-distance sound communication and remote control to seismoacoustic reconnaissance. Thus the manufacturing of compact high-power radiators emitting in a sufficiently wide frequency band is an actual task. Making the radiator shell is one of the most laborious and complicated technological operations in the process of creating and customizing hydroacoustic transducers. Unrealizable for the ordinary metalworking complex shapes of radiator's body can be produced by layering laser melting (SLM-technology). Making the radiator shell longitudinal bending-type piezoelectric active element by laser 3D-printing of metal powders eliminates the problem of encapsulation, resistance to hydrostatic pressure and reduce the parameters dispersion of the radiator to facilitate its configuration, as well as improve reliability of the transducer.

Show Abstract