bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical fibre with an offset core for SBS suppression
Authors: Khudyakov M.M. , Alekseev V.V. , Lipatov D.S. , Guryanov A.N. , Temyanko V. , Bubnov M.M. , Likhachev M.E. 
Published: February 2021

Abstract
To raise the stimulated Brillouin scattering (SBS) threshold, we have fabricated an optical fibre having a core heavily doped with germanium oxide and displaced from the fibre axis. A method has been proposed for broadening the SBS gain spectrum of the fibre by winding it onto a small-diameter spool, and a broadening of the spectrum by 5.4 dB has been demonstrated, which indicates an increase in SBS threshold by 4.1 dB.
Spectral diagnostics of an optical discharge propagating along a hollow-core optical fibre
Authors: Bufetov I.A. , Kolyadin A.N. , Yatsenko Yu.P. , Kosolapov A.F. 
Published: February 2021

Abstract
The results of spectral diagnostics of an optical discharge (OD) plasma propagating through a hollow-core revolver fibre under the action of repetitively pulsed laser radiation are presented. The revolver fibre is made of silica glass, with a diameter of the hollow core being 20 μm. The peak values of the laser radiation intensity reach 1012 W cm−2at an average Nd : YAG laser power of about 2 W. The time-averaged spectrum of the OD plasma in the visible range has the form of a continuum and is close to the blackbody spectrum with a temperature of 13.3 – 17 kK. The form of the spectrum does not depend on the gas filling of the fibre core (air or argon). In the UV part of the spectrum, lines of neutral silicon are observed, which are indicative of the partial evaporation of the reflecting cladding of the fibre.
Microstructured optical fibres with a wide single-mode range
Authors: Denisov A.N. , Semjonov S.L. 
Published: February 2021

Abstract
We have proposed a new design of microstructured optical fibres (MOFs), containing three rings of identical circular holes around a core, with different separations between the rings. The properties of the MOFs have been analysed numerically using the finite element method (FEM), and the leakage loss in the spectral range 0.40 – 2.65 μm has been calculated for the fundamental and higher order modes at various parameters of the MOFs. We have demonstrated the presence of several local maxima in the spectral dependences of the leakage loss for higher order modes and examined the physical mechanism responsible for the formation of the maxima and the variation of their position with MOF parameters. It has been shown that the proposed MOF design allows for single-mode operation in the range 0.77 – 2.3 μm.
Cross-correlation of phase fluctuations measured with a point source and an incoherent luminous object
Authors: Botygina N.N. , Emaleev O.N. , Konyaev P.A. , Lukin V.P. 
Published: February 2021

AbstractA high degree of cross-correlation of radiation wavefront aberrations, measured from a point reference source and from an extended object (a system of several luminous points), has been for the first time revealed based on simultaneous measurements of phase fluctuations in optical waves propagating in a turbulent atmosphere. The experimental data are consistent with analytical calculations. The high degree of cross-correlation (above 0.97) of measured phase fluctuations proves that an extended incoherent source can be used as a reference source to ensure the operation of an adaptive focusing system.
Zero ac Stark frequency shift of an atom trapped in pulsed laser light*
Authors: Afanasiev A.E. , Balykin V.I. 
Published: February 2021

AbstractWe report a theoretical analysis of the spectral properties of atoms localised in an optical pulsed trap. It is shown that this analysis can be carried out using the correlation coefficient calculated from the averaged dynamics of atomic excitation by resonant probe laser light in the presence of a nonresonant pulsed field. It follows from calculations that at a laser pulse duration of 8 ps, atoms can be trapped at a zero shift in the D2line transition frequency of the Rb atom, caused by the ac Stark effect. This configuration can be used to build optical frequency standards without the need for localising laser radiation at the ‘magic’ wavelength.
Laser adaptive vector-phase hydroacoustic measuring system
Authors: Romashko R.V. , Kulchin Yu.N. , Storozhenko D.V. , Bezruk M.N. , Dzyuba V.P. 
Published: February 2021

Abstract
We have developed and experimentally implemented an adaptive laser vector-phase hydroacoustic measuring system, which allows one to determine the total acoustic intensity vector. A receiving element of the measuring system comprises six spatially separated fibre-optic coil-type sensors. Signals from the sensors are phase demodulated by using a six-channel adaptive holographic interferometer based on dynamic holograms multiplexed in a photorefractive CdTe crystal. Performance of the developed measuring system has been experimentally tested by determining the bearing and localisation of a source of a weak hydroacoustic field.
Hidden structure in the spectra of strongly correlated electrons in 1D
Authors: Quinn Eoin 
Published: February 2021

Abstract
We identify a structure in the spectra of 1D lattice models of interacting electrons, characterised by an anomalous gapped branch of elementary excitations. Focussing on a family of Bethe ansatz solvable models, where all excitations are stable against decay, we make a four-way classification of the energy spectrum along with a model belonging to each class. We find in particular that the anomalous excitation branch may switch between the spin and charge symmetry sectors without a change in the ground state. Instead it changes its nature by becoming inaccessible to the ground state.
Features of the fine structure of asymmetric TE and TM modes
Authors: Egorov Yu A , Bretsko M V , Akimova Ya E , Volyar A V 
Published: February 2021

Abstract
This work is devoted to a new section of singular optics supplying a fractional topological charge on the axis. The peculiarity of this type of beams is structural instability. With a small external perturbation, these beams form optical arrays. Such optical vortices can be connected and, as it were, form an integral picture, or decay during propagation due to the fact that each of the vortices receives an additional phase swell. These studies were based on an experimental study and theoretical calculation of beams with a vector structure. And transporting optical vortices with a topological fractional charge, which is evidence of the formation of asymmetric TM (transverse magnetic) and TE (transverse electric) modes in free space. Some features of their vector “thin” structures have been studied in free space.
Development of optical imaging formation system for research of magnetic track parameters from moving object
Authors: Logunov S E , Davydov V V , Yu Rud V 
Published: February 2021

Abstract
The necessity of the magnetic track research from the moving object is substantiated. An optical system has been developed to detect a magnetic track at sea depth from the moving magnetic object. A method of processing and decoding optical images formed using a ferrofluid cell and laser radiation is proposed. The results of experimental studies are presented.
Improved 3D imaging of phase shifting digital holographic microscope by compensation for wavefront distortion
Authors: Cazac V 
Published: February 2021

Abstract
This paper is focused on improving the performance of quantitative phase imaging via phase-shifting digital holographic microscope. The development of the interferometric techniques is important for technology and biomedicine, since the surface and structure of samples can be monitored in real-time by non-destructive investigations. The novelty of the optical arrangement is that in the reference beam of the digital holographic microscope a liquid crystal variable retarder is introduced. Thus, it became possible to actively control the polarization state of light for realizing the necessary phase-shifts. In addition, a spatial light modulator is integrated in the optical setup to produce computer-controlled compensation of the spatial distortion. An ad hoc hologram processing technique was developed to execute the numerical correction of the physical phase-shifting errors. Topographical investigations of phase masks recorded on carbazol-based azopolymers provided the experimental testing of the achieved accuracy in phase reconstruction.
Modeling the image obtained by a system of vortex harmonic lenses
Authors: Khokhlov A S , Skidanov R V 
Published: February 2021

Abstract
The possibility of obtaining images using a system based on vortex diffraction lenses is considered. A system of two vortex harmonic lenses was simulated. In the system the total intensity distribution was calculated using the Fresnel transform. The width of the point spread function, which is 66 μm, is obtained. The influence of spatial filters on the result of this system is considered.
Tools for promoting a scientific article: Computer Optics journal case study
Authors: Kudryashov D V 
Published: February 2021

Abstract
The author analyzes the main tools for promoting scientific articles that are used most often by the editorial board of the Computer Optics journal to promote the publication in international scientometric databases and popularize the ideas of science. It is noted that the use of these tools allowed the publication to increase significantly the “portfolio” of articles, the number of articles published per year, including the articles in English, increase significantly the citation of journal articles in other scientific publications, as well as expand the geographical spread of authors.
Computer Information System multi-criteria optimization conditions of the complex chemical processes
Authors: Koledina K F , Koledin S N 
Published: February 2021

Abstract
An information-computing system for multi-criteria optimization of complex chemical processes has been developed. Considered sensing algorithm for solving the problem of multicriteria optimization. Information and computing system combines subsystems for solving individual computing problems. Each subsystem is designed for separate calculations-direct kinetic task, calculation of the inverse kinetic problem, multi-criteria optimization of the reaction conditions. For the catalytic reaction of the benzylalkyl ethers synthesis, using the developed information-computational system, the problem of optimizing the conditions has been solved. Based on the kinetic model, the optimal values of temperature and reaction time are determined. The values of the parameters for assessing the quality of the Pareto approximation are calculated.
Modeling of thermoelectric processes in a power MOSFET transistor with a structural defect
Authors: Sergeev V A , Hodakov A M , Kulikov A A 
Published: February 2021

AbstractThe results of thermal modeling of the temperature distribution in the structures of a high-power MOSFET transistor with macrodefects of an electrophysical nature are presented. It is shown that the presence of a defect in the structure of the transistor leads to an increase in the maximum temperature of the channel overheating and an increase in the inhomogeneity of the temperature distribution over the area of the active region of the crystal. The influence of the location of the defect on the value of the maximum overheating of the structure and the gate-source voltage is considered. The developed thermal model can serve as the basis for creating methods for diagnosing MOSFET transistors by thermoelectric characteristics and identifying defective products.
Software complex for modeling and optimization of chemical processes kinetics
Authors: Koledina K F , Almakaev R R , Koledin S N 
Published: February 2021

Abstract
A program is designed to optimize chemical reactions, allowing to carry out modeling and optimization of catalytic reactions has been developed. Implemented export and import of the reaction model and calculation of the direct kinetic problem. As an object of study, the catalytic reaction of the synthesis of benzyl butyl ether is considered. A mathematical reaction model is given and the concentrations of all reaction components are calculated.
Analytical and numerical modelling of the programmable percolation route formation when planning two-phase operations
Authors: Mostovoi Y A , Berdnikov V A 
Published: February 2021

Abstract
A swarm of robots, as a system of relatively simple interconnected managed objects, performs a common task simultaneously and in a distributed manner. When planning swarm operations associated with the creation in the service area through the front strip of the zones of the trust instrument - payload objects swarm, there is a problem of transmitting a signal from one robot to another for operational rearrangement of the swarm, as at the time of planning the exact purpose of the swarm operation has not yet been determined, or is a secret, or is determined by a number of random circumstances. The execution of the swarm operation is advisable to carry out in two phases, and the first phase to start even before the resolution of these uncertainties by creating a basic random network with a small concentration of robots in it. In the second phase of the operation, a programmable percolation route is formed by local rearrangement of the robots, which provides target coverage of the target equipment of the swarm objects of a certain service zone. In this case, you can significantly reduce the time of the operation. The corresponding analytical dependences were obtained.
Determination of heat exchange coefficient in heat conductivity problems with asymmetric boundary conditions
Authors: Trubitsyn K V , Mikheeva G V , Klebleev R M , Stefanyuk E V 
Published: February 2021

Abstract
This paper depicts an approximate analytical solution of the non-stationary heat conduction problem for an infinite plate under asymmetric boundary conditions of the third kind according to the heat balance integral method. The solution is a simple, engineering-friendly product of exponential and coordinate functions. The coordinate functions are found by the method of undetermined coefficients so that the asymmetric boundary conditions of the third kind meet the main criteria primarily. Satisfactory accuracy of the obtained solution for engineering use is provided by residual orthogonality condition abidance of the differential equation to the coordinate function obtained in this research. This method allows for errors by no more than 1% in the second approximation, in the range 1.0 < Fo < ∞ for Bi = 0 and Bi2 = 0.1. The heat transfer coefficient was determined a plate surface using the named solution along with data on the temperature change at a fixed plate spot, thus solving the inverse heat conductivity problem.
Comparative analysis of simulation options for the real geometry of the surfaces of gas turbine engine parts
Authors: Grachev I A , Bolotov M A , Pechenin V A , Kudashov E V , Kharin K E 
Published: February 2021

Abstract
Geometric deviations of parts surfaces inevitably occur during parts manufacture. It is known that the accumulated defects of parts surfaces and assembly units impact their functional characteristics throughout the entire product life cycle. Often, assembly simulation and dimensional ties analysis of products are performed by using the nominal geometry of parts without taking into account geometric deviations of the shape and location of parts surfaces. The accuracy of dimensional analysis without taking into account geometric deviations of the shape and location of parts surfaces is not sufficient to solve technological problems in digital production. The purpose of this article is the study of the influence of methods and models for constructing the real geometry on the accuracy of its reproduction. The subject of the research is the assembly unit of the rotor of a low-pressure turbine of an aircraft engine. The article considers three methods for constructing the real geometry, which are used to realize assembly virtual simulation. Comparative results of assembly simulation with the use of considered methods of real geometry constructing are presented, as well as their influence on the controlled assembly parameters is estimated.
Mathematical modeling of the process of interaction of sulfur dioxide with pyrolyzed polyacrylonitrile
Authors: Kakorina O A , Zaporotskova I V , Kakorin I A 
Published: February 2021

Abstract
The paper presents a study of the interaction of sulfur dioxide with a polymer-pyrolyzed polyacrylonitrile (PPAN). The possibility of using PPAN as an element of an electronic sensor device for recording the presence and identification of sulfur dioxide in the atmosphere is shown. The results of the established geometric and electron-energy characteristics of the polymer interacting with gas are described. Theoretical calculations were performed using the molecular cluster model and the quantum-chemical MNDO method.
Synergetic control algorithms for a multidimensional biomedical model under conditions of nonrandom and random disturbances using kernel regression
Authors: Kolesnikova S I , Avramyonok V A 
Published: February 2021

Abstract
The purpose is to investigate the applicability of the principles of the synergetic control theory to a primitive object with the initial description in the form of a system of nonlinear differential equations with a delay. In terms of intensionality, control will be here understood as the rule of intake of the substance (agent) into a living organism, which serve as antidotes to a disease, in the form of a pair of variables (time of the substance administration and amount of the administered substance). Based on a new algorithm of a discrete nonlinear analytical synthesis, three systems of control over such an object are designed for the following cases: 1) a control object is functioning under completely determined conditions; 2) a control object is affected by the deterministic unknown constrained disturbances via the control variable; 3) presence of an additive random noise on any variable. The results of a comparative numerical modeling of the designed control systems are presented, which function without any preliminary filtration of the random variable measurements and with a filtration by a kernel regression algorithm. The results can be used in the decision support systems.
Digital model of polymer molecules
Authors: Zaitsev S A , Semenov M E , Meleshenko P A , Tikhomirov S G , Chernyaev A P 
Published: February 2021

Abstract
The article is devoted to the construction and analysis of a digital model of polymer molecules. In this regard, the pseudo-random value generator (the Mersenne Vortex) from the C++ library of the C++11 standard was investigated. A method for spatial modelling of a polymer chain with free and fixed valence angles is developed and described. A software for building polymer molecules with given parameters is implemented within C++. A program for visualization of polymer structures is implemented in C#. Fractal dimensions for polymer chains with different stochastic properties were calculated. The basis for the further development of the software for simulation of radiolysis of polymers has been introduced.
Higher-order coefficients of the Williams series expansion for near crack-tip fields and their extraction from FEM experiments and digital photoelasticity method
Authors: Stepanova L V 
Published: February 2021

Abstract
Multi-parameter stress field near the Mode I crack tip in an isotropic linear elastic material is presented. The coefficients of the Williams series expansion of the stress field in the vicinity of the Mode I crack in the isotropic linear elastic material are obtained by the digital photoelasticity technique and by finite element analysis. The main objective of this study is to determine first fifteen coefficients with good accuracy and to compare the numerical results with the analytical solution for the infinite plate with the central crack. It is shown that the coefficients of the higher-order terms of the Williams series expansion are extracted with good accuracy. Comparison of the coefficients of the Williams series known from the theoretical solution for an infinite plate with the central crack and the coefficients extracted from the photoelasticity method and from finite element analysis is given. The FEM analysis is performed for a series of cracked specimens with a small crack and for a series of cracked specimens considered in the phototelasticity experiments. It is shown significant importance of higher-order terms in the Williams series expansion.
Modeling of soil dumping based on a modified Upwind Leapfrog difference scheme
Authors: Sukhinov A I , Chistyakov A E , Kuznetsova I Y , Protsenko E A , Atayan A M 
Published: February 2021

Abstract
The difference scheme is developed for the diffusion-convection problem numerical solution at large grid Peclet numbers. The scheme based on linear combination of the Upwind and Standard Leapfrog difference schemes (LCUSLDS) with weight coefficients obtained by minimizing the approximation error at small Courant numbers. The proposed approach takes into account the function of cell fullness, which allows to increase the accuracy of modeling on the area with complex geometry. The proposed modification of the Upwind Leapfrog difference scheme for the diffusion-convection problem numerical solution has better accuracy compared to other schemes considered in the article for grid values of Peclet numbers in the range 2 ≤ Pe ≤ 20. The problem of substances transport between two coaxial cylinders for large and small values of grid Peclet numbers is considered to test the proposed difference scheme. This movement of the water medium in hydrodynamics is called the Couette-Taylor flow. The steady fluid flow between two infinitely long coaxial circular cylinders is considered.
Sphalerons from the minimal 331 model and baryogenesis
Authors: Boubakir A , Aissaoui H , Mebarki N 
Published: February 2021

Abstract
The sphaleron energy and rate are investigated within the minimal 331 model. It is shown, that the constraint leading to the first order phase transition is satisfied for both spontaneous symmetry breaking vacuums of the model. A comparison with the economical model study is also made.
Ultra high energy cosmic rays
Authors: Attallah R. 
Published: February 2021

Abstract
Ultra high energy cosmic rays are the highest-energy particles ever observed in nature. Although known for more than half a century, their origin is still baffling scientists. They are most likely linked to some of the most violent phenomena in the universe but the nature of their sources remains a mystery, and so does the physical mechanism to accelerate particles to extreme energies. Here we review the different aspects of ultrahigh energy cosmic rays, emphasizing the key achievements over the past decade in our understanding of their origin. We also give a brief account of upcoming experiments and the prospects of progress in this field of research.
Dynamical study of ellipsoidal universes
Authors: Abdelali M L , Mebarki N 
Published: February 2021

Abstract
A Universe containing uniform magnetic fields, strings, or domain walls is shown to have an ellipsoidal expansion. This case is motivated from observational cosmology, especially the anomaly concerning the low quadrupole amplitude compared to the best-fit ΛCDM prediction in WMAP data. It is shown that a Universe with eccentricity at decoupling of order 10−2 can reduce the quadrupole amplitude without affecting higher multipoles of the angular power spectrum of the temperature anisotropy. The evolution of ellipsoidal Universes is studied using dynamical system techniques for the first time. The determined critical points vary between saddle and past attractors depending on dark energy state equation parameter w
Λ, with no future attractors. Numerical integrations of this dynamical system done using several initial conditions are showing new important results. For instance, a tendency for high expansion differences between planar and perpendicular axes is observed which contradicts previous assumptions on the evolution behaviour of ellipsoid Universes.