bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluating Stability Conditions for a Rotating Droplet in a Potential Flow
Authors: Sergeev M N , Evdokimov O A 
Published: December 2019

Abstract
The paper considers issues related to droplet fragmentation in air flow. We present the results of calculating the equilibrium conditions for a rotating droplet. The shape of the droplet is assumed to be ellipsoidal, and the flow is potential. The droplet equilibrium is determined by the balance of pressure due to the surface tension force, the centrifugal force and the aerodynamic effect force of the flow. We obtained an analytic expression linking the equilibrium values of the Weber number, the ellipsoid aspect ratio and the dimensionless swirl parameter. The calculation results showed that droplet swirling has a significant effect on the equilibrium conditions in a narrow range of variation in the ellipsoid aspect ratio. We obtained critical values of the Weber number and the aspect ratios for which the equilibrium state of the droplet becomes unstable.
Solution of loose medium movement problem on a curvilinear sifting surface
Authors: Kharitonov A , Busigina A , Maslennikov I 
Published: December 2019

Abstract
The paper presents the results of movement simulation of loose medium stratum on a curvilinear sifting surface using the program realizing a finite element method. The indicial equations represent an analogue describing fluid stratum movement under the theory of “shallow water”. The allocation of a part movement speed rate in the cross-section of a stratum is obtained. The presence of a braking underlayer on a sifting surface lowering efficiency of sifting process is detected.
Advanced methods and algorithms for rapid diagnosis of the organism
Authors: Berezhanskiy P V , Turchaninov S O 
Published: December 2019

Abstract
This paper deals with the methods of rapid biomedical diagnosis based on visualization of pathological states of the epithelium and microcirculatory bed, analysis of the exhaled air composition and algorithms which improve the accuracy of diagnosis with the definition of the boundaries of the medical norm for quantitative parameters.
Specifics of studying electrochlorination in a student chemistry practical
Authors: Kuznetsov N N , Bogoslovskii S Yu , Boldyrev V S 
Published: December 2019

Abstract
The suitability of the process of obtaining sodium hypochlorite by electrolytic chlorination of sodium chloride solution for the purposes in a chemical laboratory is shown. The process was carried out in a 1 l non-flowing cell with four bipolar titanium electrodes 6x10 cm with oxide-ruthenium anodes. The distance between the electrodes is 1 mm, the temperature of the initial solution is 7-8ºC. The concentration of sodium chloride 25 g/l is convenient for acquaintance with the basic electrochemical laws of the process since the dependence of the concentration of “active chlorine” on the electrolysis time is linear up to 9 g/l at a current density of 0.1 A / cm2. The study of the effect of side processes on the output of the target product is carried out at a current density of 0.125 and 0.15 A/cm2 (the dependence is nonlinear). The dependence at a concentration of 35 g/l, 0.1 A/cm2 is similar to the dependence at 25 g/l and 0.125 A/cm2. To determine the concentration of “active chlorine” the aliquot was taken from the reaction mixture at equal intervals, diluted by 25 times. The solution was acidified and titrated with methyl orange.
Numerical analysis of meniscus liner rigidity loss during its dynamic collapse
Authors: Baburin M A , Baskakov V D , Yeliseev S V , Karnaukhov K A , Tarasov V A , Zarubina O V 
Published: December 2019

Abstract
This paper describes a method of 3D computational modeling of the rigidity loss process in meniscus liners of variable thickness in circumferential direction using finite elements analysis for Lagrangian coordinates in the program complex LS-DYNA. Numerical calculations established the main consistent patterns in the process of rigidity loss in liners and the wrinkling process in the afterbody of the explosively formed projectiles formed during the dynamic collapse. Formation of a folded afterbody in explosively formed projectiles has been confirmed experimentally. The carried out research is of great interest to specialists in the field of physics of explosions and shock and impact, as well as to those involved in the analysis of rigidity loss in various constructions.
On some peculiarity in behavior of plasma with an arbitrary degree of degeneracy of electron gas in thin layer
Authors: Gordeeva N M , Yushkanov A A 
Published: December 2019

Abstract
In this study we considered the response of electron plasma with an arbitrary degree of degeneration to an alternating electromagnetic field. The electromagnetic field directed perpendicularly to the boundary of the plasma layer. We present an analytic solution of the boundary problem. The kinetic Boltzmann-Vlasov equation with the Bhatnagar–Gross–Krook collision integral and the Maxwell equation for the electric field are used. We consider the mirror boundary conditions for the reflections of electrons from the layer boundary. The boundary problem may be reduced to a one-dimensional problem with a single velocity. Separation of variables allow reducing the problem equations to a characteristic system of equations. The eigensolutions of the initial system, which correspond to the continuous spectrum, are Van Kampen mode. The eigensolutions corresponding to the adjoint and discrete spectra are Drude and Debye modes. We can construct the general solution. The Debye mode determines the plasma screening of the electric field. The behavior of this mode was analyzed. It depends on the parameters of the problem. In case of sufficiently high degrees of the electron gas degeneracy, the range of the Debye mode existence has a substantially nontrivial character, in which the ranges of existence and absence of this mode alternate with increasing electric field frequency.
Two-photon luminescence in POPOP and stilbene
Authors: Kupov M R , Gorelik V S , Sverbil P P , Lepnev L S 
Published: December 2019

Abstract
In this work, main results of spectral and energy dependences of two-photon luminescence in polycrystalline organic compounds are reported. The two-photon luminescence was excited by a repetitively pulsed laser on a yttrium aluminum garnet (YAG). This laser generated radiation at wavelengths of 266 and 532 nm. Two-photon luminescence and Raman scattering have been registered in a single measurement. We compared efficiency of two-photon luminescence and Raman scattering efficiency.
Raman scattering in diamond microcrystals and their composites
Authors: Romanovskaya A K , Gorelik V S , Bi Dongxue , Voinov Yu P 
Published: December 2019

Abstract
In this paper, the features of the Raman spectra in diamond microcrystals were investigated. The Raman spectra in microdiamonds were characterized by high intensity due to the effects of trapped radiation and total internal reflection. A characteristic line with a frequency of 1332 cm–1 and additional bands located in the overtone region of fundamental modes was registered in the observed spectra. Raman spectra in diamond-substances composites (diamond: K2Cr2O7, NaBrO3, NaNO2, HgI2, K2CrO4, PbO, KIO3, sulfur, iodine, stilbene, triglyceride sulfate, and POPOP) were detected.
Multi-frequency stimulated raman scattering in protium and deuterium water
Authors: Savelyeva A I , Gorelik V S , Voinov Yu P , Vodchits A I , Orlovich V A 
Published: December 2019

Abstract
Multi-frequency stimulated Raman scattering spectra were recorded with excitation of infrared (λ0=1064 nm) emission of picosecond solid state laser. The registration of spectra was with the fiber-optic technique by minispectrometer at wide frequency region.
Multifrequency parametric processes in dielectric media
Authors: Skrabatun A V , Gorelik V S , Pyatyshev A Yu , Vodchits A I , Orlovich V A , Apanasevich P A 
Published: December 2019

Abstract
Multiple Stokes and anti-Stokes satellites were observed in the spectra of stimulated parametric Raman scattering of light in liquids and crystals when excited by picosecond laser pulses of a YAG: Nd3+ solid-state laser with generation wavelengths of 1064 and 532 nm. The Stokes combination satellites of the infrared range were detected as a result of their conversion into the visible spectral region. The results obtained are of interest for the development of the theory of parametric processes of stimulated Raman scattering of light in crystals and liquids, which is also important for creating efficient laser sources from the ultraviolet to the far infrared.
The formula for the resistance force during slow motion of a sphere in an ideal gas
Authors: Semikolenov A V 
Published: December 2019

Abstract
In this article the formula for the resistance force during slow motion of a sphere in an ideal equilibrium gas is discussed, taking into account the velocity distribution of molecules. Using the density function of the velocity distribution of molecules hitting the surface of the body during a certain period of time, an expression for the resistance force is obtained. The resulting expression is compared with the well-known expression in the Stokes law.
X-ray free electron lasers in the course of physics of Technical University
Authors: Smirnov E V 
Published: December 2019

Abstract
The article provides an overview of the X-ray sources based on synchrotron radiation sources of the generation of the four – X-ray free electron lasers (XFEL). The multipolar system of magnetic fields – undulator – allowing receiving high intensity beams of X-rays is considered. Important properties of the radiation emitted by XFEL are noted: ultra-high brightness, ultra short pulses, the high spatial coherence of the beam. There is an urgent need to include this material in the course of general physics and in the courses of X-ray optics for Russian Technical Universities.
Dynamic crushing of spacecraft landing gear with crash legs
Authors: Scheglov G A , Lukovkin R O 
Published: December 2019

Abstract
The paper describes spacecraft landing on a landing gear consisting of four crash legs supported by beam struts. The first part is dedicated to verification of low dimension shell finite element model parameters in the MSC Nastran SOL700 software. An elastoplastic crushing test problem of square aluminum specimens with various thickness is simulated. The comparison of simulation results with experimental data shows that the proposed mathematical model provides the error of less than 10% for the specimens with a width-to-thickness ratio C/s > 30. The second part of the paper discusses landing gear legs crushing during vertical landing on a rigid soil. An analysis of the results showed that it is possible to reduce the crash legs mass by 35 % and the landing gear will provide safe landing conditions with a limited level of peak loads acting on the spacecraft. The characteristic features of the crash leg dynamic deformation process open possibilities for further reduction the landing gear weight and design optimization. The paper opens up a new avenue in design of high energy absorption lightweight gear components for the spacecraft landing process.
Kramers-Kronig relations in spectral analysis of diffuse reflected radiation
Authors: Anfimov D R , Golyak Ig S , Tabalina A S , Fufurin I L 
Published: December 2019

Abstract
In this paper studied application of Kamers-Kronig relations in spectral analysis of diffuse reflected IR radiation. Two methods of the Kramers-Kronig relations calculation were considered: Maclaurin’s Formula (MF method) and Method of Peterson-Knight (PK method). Influence of using MF and PK methods on synthetic and real experimental spectra were studied. Accuracy and calculating time of these methods were compared. According to the results of numerical experiments, conclusions about the perspectives and application possibilities of the considered methods were discussed.
Features of the formation of an electric field in a non-uniform conducting medium
Authors: Timchenko S L , Zadorozhnyy N A 
Published: December 2019

Abstract
The paper considers the influence of the electric field of the current on the behaviour of a gas bubble in an electrically conductive melt. We propose a model which makes it possible to predict a change in the size of gas bubbles in a metal, provided that its crystallization occurs in the presence of an electric current. The model takes into account the interaction of the charge induced on the surface of the gas bubble — metal-gas interface — with the electric field of the current. The force that deforms the gas bubble is introduced. The magnitude of the force is determined by the charges induced on the surface of the bubble due to the action of the electric field of the current. The surface density of the charges is proportional to the square of the current density and depends on the geometry of the object that is affected, as well as on the material parameters of the medium, such as electrical resistivity and magnetic permeability. Additional forces of electrical nature acting on the surface of the gas bubble contribute to its deformation in the electric field of the current. In the presence of such forces, the interfaces between the media — liquid metal and gaseous — can be deformed. Under the conditions of an orderly motion of free electrons and their collisions with ions of the crystal lattice, the size of the interfaces between the media can be changed. The gas bubble under the action of additional forces is deformed and can subsequently be fragmented.
Dimers of triangular Ag nanoprisms: computer simulation of optical properties
Authors: Lobanova E M , Bochenkov V E , Shabatina T I 
Published: December 2019

Abstract
In this paper the properties of a nanostructure comprised of a pair of distorted triangular Ag nanoparticles are studied using computer simulation. It is shown that upon excitation of localized surface plasmon resonance the electromagnetic field enhancement can reach the value | E | / | E0 | = 48.
Peculiarities of mathematical modeling of combustion of hydrogen-air mixtures
Authors: Kiverin A D , Melnikova K S , Minaev K O , Smygalina A E , Yakovenko I S 
Published: December 2019

Abstract
Paper presents a comprehensive study of contemporary opportunities in the numerical analysis of transient combustion regimes on the example of the topical problem of hydrogen combustion. The elementary processes determining the development of combustion under different conditions are considered. In view of this analysis, it is concluded that the most appropriate for numerical modeling of classic deflagration inside confined space is the low-dissipation numerical schemes of low (second) order of approximation. For near-critical conditions where distinct mechanisms determine the combustion development one is able to utilize the simplifications such as low Mach number approximation.
Simulation of viscoelastic flow past circular airfoil by using the modified LS-STAG immersed boundary method
Authors: Puzikova Valeria V 
Published: December 2019

Abstract
The LS-STAG immersed boundary cut-cell method modification for viscoelastic flow computations is presented. Rate type viscoelastic flow models (linear and quasilinear) are considered. Rate type viscoelastic flow models (linear and quasilinear) are considered. The obtained numerical method is implemented in the LS-STAG software package developed by the author. This software allows to simulate viscous incompressible flows by using the LS-STAG method and it modifications. The LS-STAG-discretization of extra-stress equations for viscoelastic Maxwell, Jeffreys, upper-convected Maxwell, Maxwell-A, Oldroyd-B, Oldroyd-A, Johnson Segalman fluids was developed. Formulae for differential types of convected time derivatives (Oldroyd, Cotter — Rivlin, Jaumann — Zaremba — Noll derivatives) the LS-STAG discretization was obtained. Normal non-newtonian stresses are computed at the centers of base LS-STAG mesh cells and shear non-newtonian stresses are computed at the cell corners. Time-stepping algorithm is based on the first order predictor-corrector scheme. To validate developed numerical method the test problem about viscoelastic Oldroyd-B flow past a circular airfoil was used. Computational experiments were carried out at Weissenberg number in the range from 0 to 4. The computed values of the drag coefficients and the wake length are in good agreement with the experimental data.
Spatial localization of thermal structures
Authors: Martinson L K , Pozdyshev M L , Andreev A G 
Published: December 2019

Abstract
The Cauchy problem for the integro-differential equation of nonlinear heat conduction, which describes the evolution of a finite temperature field in a medium in the presence of volumetric heat absorption, is discussed in the paper. A feature of such one-dimensional and three-dimensional processes is the spatial localization of heat, when thermal perturbations evolve in a finite spartial domain.
Comparison of combusting pellets of agro and wood biomass in different fluidized bed conditions
Authors: Kaczyński K , Kaczyńska K , Pełka P 
Published: December 2019

Abstract
The rise in pellet consumption has resulted in a wider variety of materials for pellet manufacture. Thus, pellet industry has started looking for alternative products in relation to wood biomass, such as wastes from agricultural activities, and related industries, along with the combination thereof, obtaining a broad range of these products. The results of the experiment showed significant differences between the analyzed biomass fuels burned under different operating conditions in a laboratory reactor with a model circulating bed. These differences are mainly associated with problematic phenomena during combustion, including sintering of ashes.
Experimental and numerical analysis of multi-disc heat exchanger efficiency in adsorption chillers powered with waste heat
Authors: Sosnowski M 
Published: December 2019

Abstract
The thermally-powered adsorption cooling systems capable to utilize industrial waste heat sources and environmentally friendly refrigerants are an effective way to decrease electricity demand due to cooling. The design of the heat exchanger combined with the sorption bed is crucial to enhance the heat transfer within the bed and in consequence, significantly contributes to the adsorption chiller efficiency. Therefore, the aim of the carried out research was to investigate the possibility of implementing the innovative multi-disc heat exchanger in an adsorption cooling technology. The logarithmic mean temperature difference, as well as temperature distribution within the investigated heat exchanger, were obtained with experimental and numerical research.
Microlasers based on GaAs and Si
Authors: Zhukov A E , Maximov M V , Kryzhanovskaya N V 
Published: December 2019

Abstract
Results are presented on microlasers with quantum dot active region grown on either GaAs or Si substrates. The optical resonator of these lasers represents a microdisk supporting whispering-gallery modes with a Q-factor in excess of 30’000. When operating in continuous-wave mode without temperature stabilization, the microlasers have the threshold currents of mA-range with the minimal threshold current density of 250 A/cm2. Under direct small-signal modulation, the -3dB modulation bandwidths were measured to be above 6 GHz with a little effect of self-heating on the performance. The consumed electric power was estimated to be about 2 pJ/bit. The achieved performance is a significant breakthrough in realization of low-threshold high-speed temperatrure-stable operation of microlasers compared with the previously reported parameters for the devices of comparable sizes.
Anomalous lasing in VCSEL with double oxide current apertures
Authors: Bobrov M A , Blokhin S A , Maleev N A , Kuzmenkov A G , Ustinov V M 
Published: December 2019

Abstract
Detail measurements and full-vector three-dimensional FDTD technique were used to analyze anomalous mode behavior in double-aperture oxide-confined 850 nm VCSELs with large gain-to-cavity detuning.
Reactor materials for high purity HVPE GaN growth: a thermodynamic analysis
Authors: Voronenkov Vladislav , Bochkareva Natalia , Zubrilov Andrey , Leonidov Andrey , Shreter Yuri 
Published: December 2019

Abstract
The chemical resistance of quartz, aluminum oxide, boron nitride, molybdenum, and platinum in the environment of the hydride vapor phase epitaxy of gallium nitride was estimated by chemical equilibrium calculation. The interaction of materials with hydrogen, hydrogen chloride, chlorine, ammonia, and gallium chlorides was analyzed. The conditions in which the use of each material is permissible were determined.
Selective area epitaxy of n+-GaN layers on SiO2 patterned GaN/c-Al2O3 templates by PA MBE
Authors: Shubina K Yu , Mizerov A M , Timoshnev S N , Mokhov D V , Nikitina E V , Kim I , Bouravleuv A D 
Published: December 2019

Abstract
The n+-GaN epilayers were synthesised by PA MBE on the SiO2 patterned GaN/c-Al2O3 templates, grown by MOCVD. Formation of the polycrystalline GaN atop of the SiO2 mask during PA MBE was observed. It was found that macroscopic voids at the interface polycrystalline GaN/SiO2/n-GaN template appeared during the PA MBE process. The polycrystalline GaN film was completely removed by etching in hot aqueous KOH solution. Hall measurements have shown that the value of electron concentration in n+-GaN contact layer is about ne∼4.6×1019 cm-3.
Structure of V-defects in a-GaN films grown on r-sapphire substrate
Authors: Savchuk A , Akhmerov Yu , Chelny A , Abdullaev O , Rabinovich O , Mezhenny M , Zharkova A , Aluyev A , Zakusov M , Kourova N , Murashev V , Didenko S 
Published: December 2019

Abstract
The a-GaN films were successfully grown on the r-sapphire substrate by MOCVD method. The structure of V-defects was investigated by AFM and SEM. The dependence of V-defects density on growth temperature of a-GaN film at a constant hydrogen flow through a TEG source was studied. The influence of V/III ratio on V-defects structure was investigated. Methods of V-defects density minimisation were purposed.
The two-stage electrochemical deposition of a manganese-doped silicon-carbon film onto the silicon (100) substrate
Authors: Mikhailova T S , Grigoryev M N , Myasoedova T N 
Published: December 2019

Abstract
Manganese-doped silicon-carbon films with a thickness about 100 nm were deposited on a silicon substrate by using the electrochemical route from the methanol, hexamethyldisilazane and manganese sulfate (CH3OH, (CH3)3-Si-NH-Si-(CH3)3 (HMDSN), MnSO4·5H2O) solution. At the first stage, the current density decreased from 51 mA/cm2 to less than 37 mA/cm2 with increasing the deposition time and slightly increased at the second stage when manganese sulfate was added. The analysis derived from the X-ray diffraction pattern indicates that Mn atoms interact with Si atoms and form mainly Mn5Si2 and Mn22,6Si5,4C4 phases.
In situ study of structural transformation of the (TeO)x(Mo,V,Nb)5O14 mixed oxide nanocatalyst with a tunnel structure
Authors: Derevyannikova E. , Kardash T , Marchuk A , Simanenko A. , Svintsitsikiy D. , Lazareva E. 
Published: December 2019

Abstract
The nano oxides (TeO)x(Mo,V,Nb)5O14 with so-called M1 structure are highly attractive objects due to unsurpassed catalytic properties. In situ X-ray powder diffraction method with high time resolution (0.4 seconds per diffraction pattern) was applied to study the structure stability and the mechanism of phase transformation under heating in the reductive conditions. It was shown that M1 structure gradually transforms into the rutile-type (Mo,V,Nb)O2 phase without intermediate phases and/or amorphisation at temperatures >480°C in a reductive media. The process is initiated by tellurium reduction and its sublimation to the gas phase.