bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of computer vision and neural network analysis to study the structure and dynamics of turbulent jets
Authors: Abdurakipov S , Tokarev M , Butakov E , Dulin V 
Published: December 2019

Abstract
In this paper we solved the problem of detecting and detailed analysis of the characteristics of coherent structures in non-swirling and swirling turbulent jets from the 3D PIV experiment and DNS modelling database. To solve the problem intellectual approaches of computer vision based on deep neural networks were applied. It is shown that with the use of a generative competitive neural network, it is possible to reconstruct the structure and dynamics of a turbulent flow with an increased spatial resolution, which is important for analysis and interpretation. The approach is based on a modification of the loss function, which minimizes the residual part of the hydrodynamic equations (the continuity equations and the Poisson equation) for the reconstructed data. It is shown that generative models are more effective in the reconstruction of high moments of turbulent flow than conventional methods POD and DMD. Using a fully convolutional neural network, an automatic segmentation of the turbulent jet flow region and the external environment based on instantaneous velocity and pressure fields was carried out. For a swirling jet, the area of reversed flow is identified. It is shown that the complex of the developed machine learning algorithms successfully copes with the localization of coherent structures, the detection of their trajectory, characteristic size and phase propagation velocity. The obtained new fundamental information is important for a deeper understanding of the role of vortex structures in mixing processes in a jet flow. The developed complex of algorithms for the identification and analysis of characteristics of coherent structures can be applied to a database of measurements and numerical simulation of a wide class of hydrodynamic flows.
Peculiarities of the acousto-optical interactions of Bessel light beams in crystals
Authors: Belyi V N , Kulak G V , Krokh G V , Ropot P I , Shakin O V 
Published: December 2019

Abstract
The noncollinear acousto-optical filtration of diffracted Bessel light beams in uniaxial paratellurite crystals has been investigated. With the use of the method of overlap integrals it is shown that independently on the order of Bessel light beams in the conditions of transverse phase-matching of diffracted waves in the range of optical spectrum of 0.4-1.1 nm in paratellurite crystals the bandwidth of transmission of ∼0.52 nm is reached due to detuning from Bragg’s synchronism only. It is shown that in uniaxial gyrotropic crystals polarization-independent diffraction of Bessel light beams is possible, i.e. Bragg diffraction efficiency is independent of the polarization state of the incident beam. It has been stated that the physical reason of such diffraction is simultaneous realization of two processes of anisotropic scattering under which the Bragg synchronism conditions are realized for the orthogonally polarized elliptical Bessel beams.
Modeling pictures of the flow past rough and smooth surfaces in the program comsol multiphysics
Authors: Thu Win , Ilin D V 
Published: December 2019

Abstract
The aim of this work was to obtain simulated flow patterns of rough surfaces by aerodynamic flow at different speeds for comparison with the results obtained by anemometry from images of particles in a laboratory wind tunnel. The results obtained by the program Comsol Multiphysics, which is used to simulate complex high-turbulent flows characteristic of gas flows in aircraft engines and gas turbine plants.
Compact interferometer for precise shape testing of large-size convexaspherical mirrors
Authors: Gavlina A E , Novikov D A , Sergeeva M V 
Published: December 2019

Abstract
A model of an interferometer for testing of convex aspherical mirrors up to 250 mm in diameter based on the scheme of orthogonal rays is presented. An algorithm for interferogram processing has been developed. The results of measurements of the profile of a convex spherical mirror on the presented interferometer are presented.
Optical-acoustic diagnostics of cracks on the surface of solid bodies
Authors: Kazak N S , Kulak G V , Nikilaenko T V , Matveeva A G , Shakin O V 
Published: December 2019

Abstract
The features of optical-acoustic diagnostics of defects in the form of cracks on the surface of solid bodies in a pulsed mode are investigated. It has been established that pulsed surface Rayleigh waves should be used to detect cracks. The largest amplitude of the scattered surface acoustic wave is achieved at the optimum width of the laser spot, directed to the center of the crack.
Separate BOS-visualization of temperature and pressure distributions in a solid medium
Authors: Sychev D G 
Published: December 2019

Abstract
Background Oriented Schlieren (BOS) is a technique widely used for visualizing disturbances in optically transparent objects. This method makes possible to visualize the variation of the refractive index, which depends on such physical parameters as temperature, pressure and concentration. Therefore, obtaining information about these parameters is also possible. In the course of the work, an experiment was conducted to visualize the optical inhomogeneity formed by changes in pressure and temperature in plane-parallel glass plate. Processing of experimental data has shown that under certain conditions it is possible to obtain information about the individual parameters of the environment which forms a complex inhomogeneity.
Micro-PTV technique application to velocity field measurements in immiscible liquid-liquid plug flow in microchannels
Authors: Kovalev A V , Yagodnitsyna A A , Bilsky A V 
Published: December 2019

Abstract
The present paper presents the results of micro-PTV technique application to velocity fields measurements in plug flow of immiscible liquids in T-shaped straight and curved microchannels. The data processing algorithms are described; the procedure for velocity circulation assessment was proposed and applied to measure velocity circulation in aqueous plugs at different flow rates. The comparison with micro-PIV technique application results is performed.
Elimination of distortions on images in the existence of turbulence
Authors: Belov S Yu 
Published: December 2019

Abstract
The aim of the study is to eliminate the influence of the turbulence model on the photographed images. This problem is solved by computer processing of images containing such distortions. In the course of the work, images with simulated turbulent distortions were obtained, and they were also post-processed using cascade filters.
Laser diagnostics of the instability onset in the confined vortex flows
Authors: Naumov I V , Tsoy M A 
Published: December 2019

Abstract
This paper focus is the application of optical methods of pulsating vortex flow diagnostics on the example of swirling flow instability in a cylinder with rotating lid and aspect ratio h = 3.3, 3.4. To obtain a complete picture of auto-generated pulsations development, long-term LDV measurements of the tangential velocity component were carried out with a continuous method of the Reynolds number variation from 2000 to 3500 over 8 hours (30,000 seconds). In the view of the smallness of the Reynolds number increase rate ΔRe / Δt = 0.05 s−1, this process can be considered as quasi-equilibrium. A comparison with the widely used discrete method of the Reynolds number variation is made, given range of the Reynolds numbers was studied with a step ΔRe = 50 for 20 minutes per point. It was found that at the same h, Re different vortex structures are formed depending on the Reynolds number variation method. In the case of discrete the Reynolds number variation, the development of pulsations may require up to 2000 rotating lid revolutions or 500 seconds, it should be considered conducting the experiments.
High speed visualization of self-oscillation of axisymmetric cavitating cavity in a square vortex chamber
Authors: Skripkin S G , Tsoy M A , Kuibin P A , Zuo Zhigang , Liu Shuhong 
Published: December 2019

Abstract
An experimental investigation of the multiphase turbulent flow in a square vortex chamber was carried out to examine the self-oscillation of a cavitating cavity in a wide range of flow rates and pressure conditions. Such phenomenon is observed behind turbine runner when the hydraulic units operate at full load regime at high flowrate, and leads to significant flowrate and pressure pulsations in the entire hydraulic system. The dynamics of the cavity over time, and the freaquency of the volumetric oscillations frequency was studied via high speed visualization. The grey-scale images of the vortex cavity were binarized. By assuming an axially symmetric flow, the volume of cavity for each frame was integrated, and further investigated using FFT. Quantitative information on the structure of a single-phase flow was also obtained using the PIV technique.
Compensation of spectral image shift in AOTF-based system
Authors: Bykov A A , Zinin P V , Bulatov K M , Khokhlov D D , Kutuza I B 
Published: December 2019

Abstract
Recently, it was shown that the use of a tandem acousto-optic tuneable filter (TAOTF) in combination with a camera allows one to measure the temperature distribution at the focus of a laser beam on an object’s surface. The TAOTF advantage is a reduction of aberrations and spatial distortions. Unfortunately, a TAOTF significantly reduces the intensity of the transmitted light beam, requires longer exposure time and often hampers temperature measurements below 1200 K. A single-crystal AOTF is free from this drawback and allows increasing the intensity of the incident radiation to the camera sensor. The paper presents experimental data for comparing measurements of the temperature distribution at the laser focus, obtained using single-crystal AOTF and TAOTF. A strong chromatic drift caused by AOTF-based system was compensated using the digital processing of the spectral images.
A review of non-polar liquids as materials for bulk acousto-optic devices operating with terahertz radiation
Authors: Nikitin P 
Published: December 2019

Abstract
In this paper, the acoustic and optical properties of a number of liquids transparent in the terahertz range are systematized. The acousto-optic quality is calculated for the quasi-orthogonal and collinear geometry of the acousto-optic interaction. The parameters of acousto-optic deflectors and filters of terahertz radiation are determined. The diagrams linking the resolution for the filter and the maximum number of resolvable elements for the deflector with the diffraction efficiency are given.
Application of the particle trajectory imaging for modelling dusty plasma levitation on the Moon
Authors: Poroykov A Yu , Bednyakov S A , Zaharov A V , Dolnikov G G , Lyash A N , Shashkova I A , Kuznetsov I A 
Published: December 2019

Abstract
The future robotic and human lunar landing missions to the Moon has many factors which turn them into difficult technology and science tasks. One of these factors is the influence of the dust. Upper layers of the regolith are an insulator. The regolith exposed to permanent bombardment by micrometeorites and acquire a charge due to solar wind fluxes and solar UV radiation. These factors create a charge distribution on the surface of the Moon: positive on the illuminated side and negative on the night side. On the day side of the Moon near the surface layer exists possibility of formation an electric field. Charged dust particles of micron and submicron sizes can take off and levitate over the surface. The aim of the work is to get visualization of the dynamic of dust particles under a charged surface with simultaneously estimating its parameters as accurately as possible. The experimental setup based on vacuum chamber for physical modelling of dusty plasma levitation is described. For visualization of the dust particles trajectory a stereo system of two cameras with a laser as source of illumination is used. Image processing techniques for estimating the particle trajectory in three dimensional coordinates and examples of processing results are presented.
Computer modeling of acoustic standing waves in the coolant of nuclear power plants
Authors: Proskuryakov K N , Anikeev A V , Afshar E 
Published: December 2019

Abstract
In nuclear power plants (NPPs), the dynamic interactions of the coolant with the structures are among the main factors determining the dynamic loads on the equipments, its service life and reliability. The most hazardous is the resonant interaction of vibrations of the equipment with acoustic standing waves (ASW) that arise in accidental conditions. It is pointed out that the study of accident conditions on a full-scale object model is not possible and, accordingly, the development of adequate computer models to simulate the conditions is of prime importance. The analysis of acoustic systems with single-phase and two-phase fluid media is based on the theory of elastic wave propagation in liquids and gases. The analysis is based on the equations of fluid state, equations of motion, continuity equation and the equation expressing the law of conservation of energy. It is shown that in view of the unity of the differential equations of acoustic and electrical systems, the study of the propagation of the volume flow rate of one-dimensional pulsating flow of a compressible single-phase or two-phase fluid in the acoustic system can be replaced by the study of the propagation of electric current in the lines of electrical circuits. The paper presents an acoustic scheme of the NPP coolant circuit formed by acoustic elements considering their inherent thermal-hydraulic and geometric parameters. It is shown that the results of calculations of the frequencies of the ASW are confirmed by the measurements carried out at the NPP.
Determination of parameters of the compelled capillary disintegration of liquid jets
Authors: Boukharov A V , Kukanov S I 
Published: December 2019

Abstract
The technique of the automated precision parameters diagnostics of the compelled capillary disintegration of liquid jet is developed for the solution of heat-physical problems of receiving the stable monodisperse drop streams. The analysis of the images received from two digital cameras, located at the angle ninety degrees to each other is the basic of this procedure. One of cameras fixes the image of a drop flow in plane X, another - in plane Y. The minimum time of storing images is ∼0.1 microsecond. By means of specially developed software in the “on line” mode it is possible to process images and to determine the following parameters: jets speed, drops speed, jets length, jets diameter and drops diameter. Testing on objects with the known geometrical sizes confirmed working capacity and efficiency of the technique and the software. The relative error of parameters determination does not exceed 0.5% for jets with length of several millimeters. The developed technique and the software allow to increase the accuracy and reliability of parameters determination of compelled capillary disintegration of liquid jets and drop streams and expand possibilities of parameters control of setups for receiving monodisperse streams.
Visualization and PIV-study of the formation of a cooling film when flowing around the leading edge of the gas turbine nozzle blade
Authors: Veretennikov S V , Evdokimov O A 
Published: December 2019

Abstract
The results of particle image velocimetry near the perforated leading edge of the nozzle vane of gas turbine are presented. Visualization of the formation of cooling film on the surface of the blade with determination of its thickness is carried out. On the basis of the obtained results, the influence of the blown cooling air mass flow rate on the formation of the film is analyzed.
Estimating the quality of stereoscopic endoscopic systems
Authors: Naumov A A , Gorevoy A V , Machikhin A S , Batshev V I , Pozha V E 
Published: December 2019

Abstract
Stereoscopic video endoscopic systems are widely used for the control of hard-to-reach objects at the stages of production, assembly and testing of various devices. Using a stereoscopic endoscope as a measuring tool requires its geometrical calibration. The effectiveness of such systems is largely determined by the quality of an image, based on modulation transfer function (MTF) of the optical system. In this paper, we describe and test an algorithm for automatic calculating the MTF for images of a plane test object with chessboard pattern. Experimental data was obtained using two self-developed prism-based endoscopic stereoscopic systems. Coincidence of computer simulation results and results of applying the proposed algorithm shows its effectiveness for estimating the image quality provided by stereoscopic endoscopic systems.
On computer modelling of operations, geometric characteristics and methods of pulsed optical tomography of nuclear fuel microobjects
Authors: Domoratskiy E P , Baybikova T N 
Published: December 2019

Abstract
The paper refers to the area of morphological processing of projection images and its goal is to design some computer models of basic operations, geometric properties and methods of pulsed optical tomography which provide a high-speed production operational control and sorting of each microobjet (MO) of nuclear fuel in their flow according to their size and shape. Based on the proposed computer models, a precision laser method of industrial differential control and quality control of an MO flow of nuclear fuel was developed and experimentally tested. The method uses the statistical reconstruction of the size (D) and shape (K) of each microobject and takes into account the overall dimensions of the outlines of three mutually orthogonal two-dimensional pulsed discrete projection images of a microobject. The processing speed of this method is 100 MO/s in the diameter range of 400–1500 µm. The relative error of an MO diameter control is no more than 0.25% (at the reliability of PD
= 0.7 and K = 1.3 relative units), and the relative error of the non-sphericity coefficient control lies in the range of 2.3% (PK
= 0.7 and K = 1.3) to 0.6% (PK
= 0.96 and K = 1.05).
Study of convective structures and phase transition induced in a water layer by non-stationary boundary conditions
Authors: Dubnishchev Yu N , Arbuzov V A , Arbuzov E V , Berdnikov V S , Zolotukhina O S , Kislitsin S A 
Published: December 2019

Abstract
The problem of reconstructing interference and Hilbert structures from a numerical model of the evolution of the thermal field of convective flows in a water layer bounded by flat heat-exchanging surfaces under unsteady boundary conditions in the monotonic cooling mode and taking into account density inversion at a temperature of +4 °C was solved. The simulation of the thermal fields of convective flows in the form of the dynamic structure of isotherms was carried out taking into account the nonlinear dependence of thermal conductivity and water density on temperature. The field of the phase function, its Hilbert image and the interference field, which are compared with the results of the interference and Hilbert visualization of the fields of phase optical density obtained in the experiment, were reconstructed from the isotherms field supplemented by calculating of the velocity field and of the temperature gradients field. The presented films illustrate the qualitative adequacy of the coevolution of numerical models and real processes.
Infrared fiber based on AgCl-AgBr and AgBr-TlI crystals to transfer thermal radiation in pulsed
Authors: Shmygalev A S , Korsakov A S , Zhilkin B P , Turabi A 
Published: December 2019

Abstract
The our research objective is to study IR energy transfer in pulsed and continuous mode through optical fibers produced from crystals of silver halide and a monovalent thallium solid solutions. It is assumed that the transfer of infrared radiation in the pulsed mode will significantly reduce losses. We designed the experimental setup, determined its operational parameters, and obtained the dependence of the detector’s received radiation on the frequency of the pulses of thermal radiation. As a research subjects we used two different fibers compositions namely AgCl0.25Br0.75 and Ag0.95Tl0.05Br0.95I0.05.
Experimental study of the multiphase flow in a pore doublet model
Authors: Zamula Yu S , Batyrshin E S , Latypova R R , Abramova O A , Pityuk Yu A 
Published: December 2019

Abstract
The paper presents the results of an experimental study of the properties of single-and multiphase flows in a “pore doublet model” (PDM) using microfluidic and optical microscopy techniques. Polymer based microfluidic devices containing pore doublet were fabricated using soft lithography methods. The average cross-section of the microchannels was in the order of 100 μm, and the length reached several millimeters. A bubble generator in the form of a T-junction microchannel was fabricated to study the multiphase flows. High speed imaging and tracer visualization methods were used to study the flow patterns. The properties of multiphase flows were studied during liquid-gas displacement and bubbly liquid flow through pore doublet. The flow patterns were visualized using polymer micro particles suspended in flowing liquids.
The method of compensation for local displacements of images of capillaries in the evaluation of capillary blood flow parameters
Authors: Volkov M V , Margaryants N B , Potemkin A V , Gurov I P 
Published: December 2019

Abstract
The paper discusses the features of applying the method of local compensation of video frame displacements in the study of microcirculation parameters by the methods of video capillaroscopy (VCS) and microphotoplethysmography (micro-PPG). The results of the assessment and compensation of local displacements of images of the capillary network in the region of the hand of a conditionally healthy volunteer are presented. The result of the computation of the synthesized image of capillaries with equalized contrast based on the processing of a locally-combined sequence of video frames is shown. An example of capillary visualization using the frequency analysis of locally aligned video frames is given. The effectiveness of the method of local image stabilization within the study of the capillary network of mucous membranes using a laparoscope is demonstrated.
Installation for investigation of optical and mechanical system of fiber optical sensors of parameters of liquid or air flows
Authors: Badeeva E , Shachneva E , Murashkina T , Kukushkin A 
Published: December 2019

Abstract
A special measuring unit has been developed for experimental studies of micro-optomechanical systems of fiber-optic micro-angle transducers based on a bellows and micrometer, which are the basic elements of fiber-optic sensors of aerodynamic angles, imitating the physical effect of the flux on the sensing element.