bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emission of xenon in the spectral range of 120 – 800 nm upon excitation by diffuse and spark discharges
Authors: Panchenko A.N. , Beloplotov D.V. , Kozhevnikov V.V. , Lomaev M.I. , Sorokin D.A. , Tarasenko V.F. 
Published: June 2021

Abstract
Xenon emission in the spectral range of 120 – 800 nm upon excitation by subnanosecond voltage pulses is investigated. Excitation is performed using diffuse and spark discharges in an inhomogeneous electric field at a xenon pressure ranging from 0.3 to 3 atm. It is shown that xenon excitation by a series of successive 0.7-ns voltage pulses with a pause of 30 ns leads to a decrease in the second-continuum radiation intensity by the second and subsequent voltage pulses and an increase in the first-pulse afterglow intensity. It is confirmed that in the case of a pulsed diffuse discharge, the second continuum of xenon dimers, which is used to generate laser and spontaneous radiation in the VUV spectral region, makes the largest contribution to the radiation energy. Broadband radiation in the visible range (λ > 400 nm) is found to occur when the discharge is constricted. The obtained results indicate that the influence of the dynamic displacement current on the pin-diode caused a measurement error in the papers by V.I. Baryshnikov et al., who did not record the second-continuum radiation from xenon excited by a short homogeneous discharge.
Transverse mode locking of the Stokes component of a diode end-pumped Q-switched Nd : KGW laser
Authors: Koromyslov A.L. , Tupitsyn I.M. , Cheshev E.A. , Chulkov R.V. 
Published: June 2021

Abstract
Lasing in a solid-state inhomogeneously diode end-pumped Nd : KGW/Cr4+ : YAG laser is obtained at wavelengths of 1067 and 1181 nm (Stokes shift 901 cm−1) under conditions of frequency degeneracy of cavity modes. In this case, the radiation has a characteristic ring spatial structure, which testifies to transverse mode locking of the fundamental and Stokes components. The possibility of controlling the Raman conversion efficiency by changing the position of an undoped KGW crystal additionally installed in the cavity is demonstrated. It is shown that the transverse mode locking is accompanied by the total longitudinal mode locking at λ = 1067 and 1181 nm.
Suppression of nonlinear distortion in a high-speed multichannel communication line with variable quadratic dispersion compensation
Authors: Shapiro E.G. , Shapiro D.A. 
Published: June 2021

Abstract
We report a numerical simulation of the propagation of short (25 ps) 8QAM pulses for two polarisations in a nine-channel communication line with a frequency band of 80 GHz. It is shown that the use of large-chirp pulses and different dispersion compensators leads to effective suppression of nonlinear distortions and significantly improves the signal quality in a multichannel communication line due to the rapid pulse broadening.
Two-photon absorption of light beams of variable cross section
Authors: Gordeev A.A. , Efimkov V.F. , Zubarev I.G. 
Published: June 2021

Abstract
An equation is obtained to describe two-photon absorption of light beams of variable cross section. It is shown that the experimental values of the two-photon absorption coefficients of focused laser beams, calculated in the plane-wave approximation in the focal waist region and taking into account the variable cross section of the light beam, differ by two orders of magnitude.
Possibility of resonant three-photon isotope-selective excitation of vibrational states with υ = 3 of the UF6molecule mode ν3by radiation from two pulsed IR lasers in a gas-dynamically cooled molecular flow
Authors: Makarov G.N. 
Published: June 2021

AbstractWe consider the possibility of resonant isotope-selective population of states withυ= 3 of the vibrational modeν3of UF6molecules as a result of three-photon bichromatic excitation of the molecules by IR radiation from two pulsed CF4lasers and two pulsed para-H2lasers. We propose specific schemes and analyse the possibility of exciting the238UF6and235UF6molecules into states withυ= 3 of the vibrational modeν3using two CF4lasers (or para-H2lasers) generating in the region of 16 μm at frequencies that are significantly (by ∼3.5 – 17 cm−1) detuned from the linear absorption bands at the frequencies ofν3vibration of these molecules in a gas-dynamically cooled molecular flow. However, the sum of the doubled lasing frequency 2νL1of the first laser and the frequencyνL2of the second laser is equal to a frequency of the transitionυ= 0 →υ= 3 of the vibrational modeν3of the UF6molecules. When both laser pulses coincide in time, the possibility of selective excitation of UF6molecules from the ground vibrational state withυ= 0 to the state withυ= 3 of the vibrational modeν3is realised. The proposed schemes for the excitation of UF6molecules to states withυ= 3 are compared with the previously implemented schemes for the effective excitation of states withυ= 3 of the vibrational modeν3(F1) and states withυ= 2 of the vibrational modeν3(A1) of SF6molecules by three- and two-frequency radiation of pulsed CO2lasers, respectively.
Q-switched lasing in ZrO2 – Y2O3 – Ho2O3 crystals
Authors: Artemov S.A. , Artemov E.A. , Lomonova E.E. , Ryabochkina P.A. , Chabushkin A.N. 
Published: June 2021

Abstract
The energy and time characteristics of Q-switched two-micron lasing at the 5I7 → 5I8 transition of Ho3+ ions in ZrO2 – Y2O3 – Ho2O3 crystals are studied under resonance pumping to the 5I7 level by a cw Tm : LiYF4 laser. The mechanisms of appearance of burns on the faces of the ZrO2 – Y2O3 – Ho2O3 active elements at high laser energy densities are proposed.
Effect of elastic anisotropy on thermally induced distortions of a laser beam in single cubic syngony crystals with radial cooling. Part III
Authors: Vyatkin A.G. 
Published: June 2021

Abstract
We report a study of thermally induced depolarisation of a laser beam in single cubic syngony crystals of 23 and m3 symmetry groups with an anisotropic elastic stiffness tensor. For active elements in the form of a long rod and a thin disk with radial cooling under uniform volume pumping, we investigate the effect of anisotropy of elastic properties on the dependence of the degree of depolarisation in the crystal on the orientation of the crystallographic axes, as well as on the position of the critical orientation in the crystallographic coordinate system.
Hidden or subclinical cochleopathy in idiopathic subjective tinnitus
Authors: Morgan Ashraf Elsayed , Elghandour Amira Mohammed Ahmed , Abdeltawwab Mohamed Mustafa 
Published: June 2021

Introduction
Tinnitus patients with apparently normal hearing represent a challenge to models of tinnitus generation which rely on compromised cochlear function. Although it is known that any cochlear changes even subclinical can cause tinnitus, our rational was to apply an objective measure that can aids in the quantification of these cochlear changes.

Objective
The of study was designed to evaluate possible hidden or subclinical cochlear dysfunction in idiopathic subjective tinnitus patients with normal hearing using extended high frequency audiometry and otoacoustic emissions.

Methods
Forty seven subjects enrolled in this study divided into control group (20 normal hearing adults without tinnitus) and a study group (27 normal hearing adult patients complaining of tinnitus). Extended high frequency (EHF) audiometry and otoacoustic emissions (OAEs) in addition to tinnitus matching study were done for all subjects. Study group further subdivided according to tinnitus pitch matching into low- and high-pitched tinnitus groups.

Results
The data of this study showed that patients with normal hearing sensitivity in the conventional frequency range (up to 8 kHz) and reporting tinnitus, present alterations of the auditory system in the affected side. This affection manifested as elevated EHF audiometry thresholds at 9000, 10,000, 11,200, 14,000 and 16,000 Hz. Most tinnitus patients had pitch matching frequency at high frequency range between (3000 and 8000 Hz). Transient evoked OAEs and distortion product OAEs amplitude was lower in tinnitus patients relative to controls.

Conclusion
The ultrahigh frequency hearing loss is not hidden – but – exists and awaits identification with appropriate testing.
Changes in Mechanical and Microstructural Characteristics of Demineralized Tooth Enamel after Conventional and Modified Infiltration Techniques
Authors: Gileva O S , Levitskaya A D , Mudrova O A , Daurova F Y , Zuev A L 
Published: June 2021

Abstract
The research carried out a comparative assessment of the physical and mechanical properties of tooth enamel: healthy; demineralized; demineralized and subsequently infiltrated with a flowable composite according to a standard or modified technique. An original in vitro model of artificial caries of human tooth enamel was used for the study, the clinical-topographic, color-textural and physical-mechanical properties of which correspond to the characteristics of enamel caries in vivo. Comparative analysis of the results of kinetic microindentation of enamel samples allows to characterize the biomaterial from the standpoint of physical materials science, to determine the advantages and disadvantages of different regimens of resin infiltration. The advantages of the modified infiltration technique are illustrated by significantly greater, as compare with classic method, increase in microhardness and elasticity against background of a decrease in a creep index of the infiltrated enamel in itsdeep zones. The results reflect the fact of incomplete obturation of microporous in the deep layers of enamel after classical treatment.
Inclinometer-Based Long-Term Monitoring of the Headframe of Salt Mine Shaft
Authors: Glot I , Shardakov I , Shestakov A , Tsvetkov R , Gusev G 
Published: June 2021

Abstract
The paper presents a block diagram of an automated inclinometer-based system for monitoring the inclination of a high-rise metal structure of the shaft headframe. The stress-strain state of this structure is defined by the loads associated with the operation of shaft skip and the impact of the environmental factors on the structure. The data obtained by 6 inclinometers located at different height were used to determine the inclination of the headframe and distortion of its shape. Analysis of long-term observation data revealed the existence of deformation processes having different time scales (long-term, seasonal and daily). A correlation between changes in the tilt angle of the structure and ambient temperature was established. Long-term monitoring of tilt angle showed that the displacements of the structure were within the permissible limiting values. The developed monitoring system is of great theoretical importance for understanding the deformation processes arising during the operation of such structures.
Influence of the Properties of the Plate Surface on the Natural Oscillations of the Clamped Drop
Authors: Kashina M A , Alabuzhev A A 
Published: June 2021

Abstract
We consider free oscillations of a clamped liquid drop. An incompressible fluid of different density surrounds the drop. In equilibrium, the drop has the form of a circular cylinder bounded axially by the parallel solid planes, the contact angle is right. These plates have different surface (wetting etc.) properties. The solution is represented as a Fourier series in eigenfunctions of the Laplace operator. The resulting system of complex equations for unknown amplitudes was solved numerically. The fundamental frequency of free oscillations can vanish in a certain interval of values of the Hocking parameter. The length of this interval depends on the ratio of the drop dimensions. Frequencies of other drop eigenmodes decrease monotonically with increasing Hocking parameter.
Experiment on Injection of SIC and BN Nanoparticles into Liquid Aluminum Using MHD Stirring with Subsequent Crystallization of the Melt
Authors: Khripchenko S , Dolgikh V , Kiselkov D 
Published: June 2021

Abstract
The paper describes the technique and results of experiments on the introduction of SiC and BN nanoparticles into an aluminum melt contained in a cylindrical crucible with a water-cooled bottom and heated walls. The crucible was placed in an MHD stirrer, which generated a travelling and rotating magnetic fields ensuring in such a way bidirectional stirring of the liquid metal in the crucible. After introducing the reinforcing particles, aluminum was stirred and directionally crystallized. Reinforcing particles were introduced into molten aluminum as a component of pressed pellets. Pellets with diameter of 20 mm and thickness of 15 mm were made from a mixture of aluminum powder (100-156 µm) and reinforcing nanoparticles (100-200 nm) by pressing in a special pellet die. The concentration of reinforcing particles in the pellets was selected using preliminary experiments and was 5% of their total weight. In some experiments, the aluminum was reinforced with SiC nanoparticles introduced into the melt in the amount of 0.59%, 1.04%, 1.77%, while in other experiments the concentration of hexagonal BN nanoparticles introduced into aluminum was 7%, 1%, 1.8% of the ingot weight. As the experiment showed, the reinforcing particles formulated into tablets can be introduced into aluminum by means of MHD stirring. The dependence of the ultimate strength and electrical resistance of aluminum on the concentration of the reinforcing nanoparticles introduced into it has been obtained experimentally. It has been found that with an increase in the concentration of nanoparticles in aluminum, its ultimate strength and specific electrical resistance increase. The dependences of the ultimate strength and electrical resistance of aluminum on the concentration of SiC and BN nanoparticles are very similar and close to linear (in the investigated range of concentrations of introduced particles. With an increase in the concentration of introduced nanoparticles the mechanical strength of the resulting material grows faster than the electrical resistivity. In the experiments, the ultimate strength of the samples increased by 22%, while the electrical resistance increased by 5-6%. This opens up new possibilities for industrial applications of such materials, for example, in manufacture of self-supporting wires in power lines.
Strain Measurement and Defect Detection with Fiber-Optic Sensors Embedded into the Cement Sample
Authors: Kosheleva N , Serovaev G , Gusev G 
Published: June 2021

Abstract
The application of embedded into material fiber-optic sensors based on Bragg gratings for strain measurement on the example of a cement sample during the manufacturing stage, under operational loads and upon the appearance and development of a defect is studied in the paper. The integrity and performance of fiber-optic sensors at all stages of the study, as well as the efficiency of strain measurement, have been demonstrated. An approach is implemented to register the appearance and development of defects based on information received from embedded fiber-optic sensors. The approach considered in the study is based on the location of sensors in the vicinity of the expected damage. The results obtained indicate the possibility of using embedded fiber-optic sensors to assess the mechanical state of civil structures.
Studying the Kaiser Effect During Modeling of Rock Loading Conditions Using the NX-borehole Jack
Authors: Beltyukov N L 
Published: June 2021

Abstract
The paper deals with modeling the stress state experienced by rocks in a loaded around-borehole volume to justify a promising method of in-situ stress measurements based on the Kaiser effect. Mathematical modeling of loading the horizontal borehole walls with a NX-borehole jack in a direction of principal components σ1
or σ3
of the natural stress field was performed for conditions of the unperturbed salt rock mass of the Verkhnekamskoe potassium salt deposit. As a result of the numerical calculation of stresses, it was determined that recovery of radial component σr
in compression regions of the rock volume around the borehole occurs when the jack’s pressure reaches the initial value of the principal stress. At the same time, the concentration of tangential component σθ
in these regions is retained. The rock salt specimens were tested under modes similar to the stress states of the rocks in the around-borehole volume to study the Kaiser effect under these conditions using a triaxial compression vessel. It was found that in the second loading cycle, the recovery of the initial values of axial component σaxial
of the specimen stress field, unloaded after the first cycle, stimulates acoustic emission. This regularity is true for the case when there is no increase in confining pressure σconf
on the specimen between the cycles. In the conditions with an increase in confining pressure σconf
between the first and second cycles, the Kaiser effect is found at higher values of σaxial
component than the initial ones. It is shown that the nature of the effect depends on a type of a specimen’s initial stress state and is caused by the growth resumption of longitudinal microcracks, if σaxial
> σconf
in the first loading cycle, or by a closure of lateral microcracks when σaxial
< σconf
in the first loading cycle.
Preparation of the Composite Powder Al – B4C by Ball Milling for Cold Spray
Authors: Chesnokov A E , Smirnov A V , Klinkov S V , Kosarev V F 
Published: June 2021

Abstract
In the work, when ball milling of mixture of aluminum powder (ASD – 1) and boron carbide (F 500) powder in a high-energy planetary mill, composite particles sized from 10 to 100 microns were produced, in the volume of which ultrafine boron carbide particles were distributed in the size range from 0.1 to 20 microns. It is assumed that the use of such particles in the production of coatings by cold gas-dynamic spraying will increase the deposition efficiency and the weight fraction of boron carbide in the coating. An increase in the concentration of carbide particles in the processed powder mixture, under all other conditions being equal, leads to a decrease in the average volume size of the particles. It is noted that in this case, the boron carbide particles behave as a surfactant. The X-ray phase analysis has shown diffraction peaks corresponding only to aluminum and boron carbide, therefore, under the selected milling conditions, the phase composition remain the same as in the original powders.
Stability Analysis of Composite Cylindrical Shell Containing Rotating Fluid
Authors: Bochkarev S A , Lekomtsev S V 
Published: June 2021

Abstract
A semi-analytical finite element method is used to analyze the stability of composite cylindrical shells interacting with a rotating fluid inside them. A mathematical formulation of the problem of deformable structure dynamics is based on the variational principle of virtual displacements and classical shell theory. The behavior of an ideal compressible fluid is described within the framework of the potential theory. The validity of the obtained results is supported by comparing them with the known solutions. Numerical experiments were performed for two- and three-layer cross-ply shells made of boron-epoxy resin with different boundary conditions and geometrical dimensions. It is demonstrated that, for the examined configurations, an increase in the fibre angles leads to a significant increase in the critical rotation velocities of the fluid, regardless of the conditions for fixing the edges of a thin-walled structure.
Experimental Study of Polyurea Protective Coating Effectiveness for Layered Composite Material Reinforced by Glass-Fiber under Impact Loading
Authors: Sazhenkov N A , Voronov L V , Sh Nikhamkin M 
Published: June 2021

Abstract
One of the promising methods for increasing the resistance of polymer composite materials to high-speed impact is the use of protective shockproof coatings. At the same time, over the past two decades, polyurea have been gaining noticeable popularity among such coatings. This work is devoted to study the effect of polyurea coating of 1.2 mm thickness on ballistic resistance characteristics of glass-fibre reinforced layered polymer of 8.5 mm thickness. During the experiments thirteen composite targets was affected by high-speed impact loading in the range of 80…150 m/s by spherical steel projectile of 23.8 mm diameter. It was shown that using the polyurea coating can increase the ballistic limit by 19% increasing the mass of the target only by 7%. Dynamic strain and displacement fields on the back surface of the target was obtained using digital image correlation method for 81.2 m/s collision process.
On the Possibility of Describing the Microstructure of Human Dentin as Soft Matrix Filled by Solid Particles
Authors: Cheboksartseva M A , Zaytsev D , Ivashov A S , Mandra J V , Zholudev S 
Published: June 2021

Abstract
Experimental verification of the applicability of self-similar hierarchical mechanics model for calculation of the mechanical properties of human dentin was carried out. A comparison of the deformation behavior of human dentin with the several polymer based dental composites under compression and bending was performed. It was shown that the deformation behavior of some highly filled composites was close to human dentin in the elastic regime whereas they cannot be deformed plastically under compression. Low filled composites possess higher plasticity, but a lower Young’s modulus than dentin under compression. Mechanical properties of a highly filled composite (∼60%, by volume) with smaller size of fillers are closer to the properties of human dentin under bending whereas other tested dental materials have a lower Young’s modulus and flexural strength in comparison with dentin. Therefore, we concluded that it was impossible to achieve complete combination of the mechanical properties of human dentin such as high elasticity and plasticity at high strength by means of varying the amount and size of solid filler in polymer matrix. Self-similar hierarchical mechanics model can be used for describing of the deformation behavior of human dentin in elastic regime and one level is sufficient for these calculations.
Assessment of Residual Stresses in a T-joint Weld by Combined Experimental/Theoretical Approach
Authors: Tagiltsev I I , Shutov A V 
Published: June 2021

Abstract
Residual stresses are common in metal structures, essentially influencing their mechanical behaviour. We consider a combined experimental/theoretical approach to residual stresses. The theoretical basis of analysis is provided by the recently developed F0-approach, operating with explicit relation between load-free and stress-free configurations. The titanium alloy Ti-6Al-4V is modelled with the multiplicative decomposition of the deformation gradient into the elastic and the plastic parts. Isotropic hyperelastic relations between stresses and elastic strains are assumed. The weak invariance of the material model allows for incorporation of residual stresses without additional numerical costs. In order to demonstrate the new experimental/theoretical approach to residual stresses, experimentally measured stresses are extrapolated from the surface inside the welded T-joint. The robustness of the stress extrapolation procedure is confirmed on synthetic experimental data.