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Effects of pre-existing cracks and infillings on strength of natural rocks--Cases of sandstone, argillite and basalt

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第6期12卷 1333-1338页

作者： Chen Cui ivan gratchev School of Engineering Griffith UniversityGold CoastAustralia

This study aims to examine the influence of pre-existing discontinuities on the strengths of four natural rocks of different origins.A series of unconfined compression tests was performed on specimens of two types of sandstones,argillite and basalt that contain open and filled *** was found that the presence of cracks tends to decrease the overall strength for all studied rocks;however,the magnitude of strength reduction is related to the property of *** larger strength decrease was observed for the relatively harder argillite and basalt,compared to the softer *** was also found that the infill material could increase the strength of rock specimens,while the obtained strength depended on the characteristics of the fill material.

关键词： Pre-existing crack Rock strength Infill material Laboratory test

Method for passivation of propellant residues in orbital stage tank of launch vehicle

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Chinese Journal of Aeronautics 2024年第1期37卷 64-76页

作者： Valeriy TRUSHLYAKOV ivan LESNYAK Alexey PANICHKIN Department of Aviation and Rocket Building Omsk State Technical UniversityOmsk 644050Russia Sobolev Institute of Mathematics of the Siberian Branch of Russian Academy of Sciences Novosibirsk 630090Russia

The problem of removing unused liquid propellant residues from the tanks of spent spacecraft and orbital stages of Launch Vehicles(LV)leads to their explosion and the formation of space debris in *** provide a solution to this problem,a method for removing liquid propellant residues from the LV tanks after the mission completion is *** method is based on the gasification of liquid propellant residues in the tanks under acoustic-vacuum exposure and the discharge of the gasification products into the surrounding outer *** investigations were carried out on a Ground-based Experimental Installation(GEI)to determine the coefficient of heat transfer from the surface of an acoustic radiator to a *** obtained coefficient was then used to calculate the energy costs for the gasification of *** estimates are given on the example of the tank with kerosene residues from a spent second stage of the LV“Soyuz-2.1 v”.The optimal discharge rate at which kerosene does not freeze is 0.14 m^(3)/***,the acoustic exposure leads to an increase in the mass of evaporated kerosene over a given time by96.1%,and the energy costs are 1756.7 kJ(approximately 50% of the remaining electrical energy).

关键词： Propellant Weightlessness Liquid evaporation Heat and mass transfer Acoustics Vacuum Vapor bubbles

Oscillatory Dynamics of a Spherical Solid in a Liquid in an Axisymmetric Variable Cross Section Channel

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Fluid Dynamics & Materials Processing 2024年第6期20卷 1219-1232页

作者： ivan Karpunin Laboratory of Vibrational Hydromechanics Perm State Humanitarian Pedagogical UniversityPerm614990Russia

The dynamics of a solid spherical body in an oscillating liquid flow in a vertical axisymmetric channel of variable cross section is experimentally *** is shown that the oscillating liquid leads to the generation of intense averaged flows in each of the channel *** intensity and direction of these flows depend on the dimensionless oscillating *** the region of studied frequencies,the dynamics of the considered body is examined when the primary vortices emerging in the flow occupy the whole region in each *** a fixed frequency,an increase in the oscillation amplitude leads to a phase-inclusion holding effect,i.e.,the body occupies a quasi-stationary position in one of the cells of the vertical channel,while oscillating around its average *** is also shown that the oscillating motion of a liquid column generates an averaged force acting on the body,the magnitude of which depends on the properties of the body and its position in the *** quasi-stationary position is determined by the relative density and size of the body,as well as the dimensionless *** behavior of the body as a function of the amplitude and frequency of fluid oscillation and relative size is discussed in *** findings may be used in the future to control the position of a phase inclusion and/or to strengthen mass transfer effects in a channel of variable cross section by means of fluid oscillations.

关键词： Phase inclusion axisymmetric channel variable cross section oscillations dimensionless frequency averaged force viscous boundary layer

Liquid superlubricity of lubricants containing hydroxyl groups and their aqueous solution under rolling/sliding conditions

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Friction 2024年第1期12卷 164-173页

作者： Tomáš POLÁČEK Petr ŠPERKA ivan KŘUPKA Faculty of Mechanical Engineering Brno University of TechnologyBrno 61669Czech Republic

Macroscale rolling/sliding conditions are in the superlubricity,a little-studied topic so *** purpose of this paper is to examine the formation of elastohydrodynamic lubrication(EHL)films by water-based lubricants(glycerol and polyethylene glycol(PEG)),providing superlubricous *** were carried out on an optical ball-on-disc tribometer under rolling/sliding *** film thickness was measured by the thin film colorimetric interferometry,and the viscosity of liquids was measured by rotational and high-pressure falling body *** results show that tribochemical reactions are not the mandatory reason for friction to reach the superlubricity level when using the water-based *** studied liquids themselves are almost *** the addition of water,the signs of shear thinning behavior disappear even *** conditions for this type of lubricant can be predicted using the known Hamrock–Dowson *** anomaly in the thickness of the lubricants was observed as an abrupt change at certain *** more PEG there is in the lubricant,the higher the thickness at the beginning of the jump.

关键词： macroscale superlubricity super low traction water-based lubricants elastohydrodynamic lubrication(EHL) film thickness

Applying the Shearlet-Based Complexity Measure for Analyzing Mass Transfer in Continuous-Flow Microchannels

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Fluid Dynamics & Materials Processing 2024年第8期20卷 1743-1758页

作者： Elena Mosheva ivan Krasnyakov Institute of Continuous Media Mechanics UB RAS Perm614013Russia Department of Applied Physics Perm National Research Polytechnic UniversityPerm614990Russia

Continuous-flow microchannels are widely employed for synthesizing various materials,including nanoparticles,polymers,and metal-organic frameworks(MOFs),to name a *** technology allows precise control over reaction parameters,resulting in purer,more uniform,and structurally stable products due to more effective mass transfer ***,continuous-flow synthesis processes may be accompanied by the emergence of spatial convective structures initiating convective *** the one hand,convection can accelerate reactions by intensifying mass *** the other hand,it may lead to non-uniformity in the final product or defects,especially in MOF microcrystal *** ability to distinguish regions of convective and diffusive mass transfer may be the key to performing higher-quality reactions and obtaining purer *** this study,we investigate,for the first time,the possibility of using the information complexity measure as a criterion for assessing the intensity of mass transfer in microchannels,considering both spatial and temporal non-uniformities of liquid’s distributions resulting from convection *** calculate the complexity using shearlet transform based on a local *** contrast to existing methods for calculating complexity,the shearlet transform based approach provides a more detailed representation of local *** analysis involves experimental images illustrating the mixing process of two non-reactive liquids in a Y-type continuous-flow microchannel under conditions of double-diffusive convection *** obtained complexity fields characterize the mixing process and structure formation,revealing variations in mass transfer intensity along the *** compare the results with cases of liquid mixing via a pure diffusive *** analysis,it was revealed that the complexity measure exhibits sensitivity to variations in the type of mass transfer,establishing its feasibility as an ind

关键词： Shearlet analysis complexity measure entropy measure convection microchannels double-diffusive instability

Three-Dimensional Convection in an Inclined Porous Layer Subjected to a Vertical Temperature Gradient

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Fluid Dynamics & Materials Processing 2024年第9期20卷 1957-1970页

作者： ivan Shubenkov Tatyana Lyubimova Evgeny Sadilov Computational Fluid Dynamics Laboratory Institute of Continuous Media Mechanics UB RASPerm614068Russia Theoretical Physics Department Perm State UniversityPerm614990Russia

In this paper,we study the onset and development of three-dimensional convection in a tilted porous layer saturated with a *** layer is subjected to a gravitational field and a strictly vertical temperature ***,problems of thermal convection in tilted porous media saturated with a liquid are studied by assuming constant different temperatures at the boundaries of the layer,which prevent these systems from supporting conductive(non-convective)*** boundary conditions considered in the present work allow a conductive state and are representative of typical geological *** an earlier work,we carried out a linear stability analysis of the conductive *** was shown that at any layer tilt angles,the most dangerous type of disturbances are longitudinal ***,a non-zero velocity component exists in *** the present work,threedimensional non-linear convection regimes are *** original three-dimensional problem is reduced to two-dimensional one with an analytical expression for the velocity z-component v_(z)=v_(z)(x,y).It is shown that the critical Rayleigh number values obtained through numerical solutions of the obtained 2D problem by a finite difference method for different layer inclination angles,are in a good agreement with those predicted by the linear *** number of convective rolls realized in nonlinear calculations also fits the linear theory predictions for a given cavity *** carried out at low supercriticalities show that a direct bifurcation takes *** increasing supercriticality,no transitions to other convective regimes are *** situation studied in this problem can be observed in oil-bearing rock formations under the influence of a geothermal temperature gradient,where the ensuing fluid convection can affect the distribution of oil throughout the layer.

关键词： Thermal convection inclined layer porous media vertical temperature gradient

Is Veillonella a unique marker of physical exercise?Commentary on:"Is physical performance(in mice)increased by Veillonella atypica or decreased by Lactobacillus bulgaricus?"

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Journal of Sport and Health Science 2024年第5期13卷 682-684页

作者： Viktor Bielik ivan Hric Riadh Hammami Department of Biological and Medical Science Faculty of Physical Education and SportComenius University in BratislavaBratislava 81469Slovakia Department of Molecular Biology Faculty of Natural SciencesComenius University in BratislavaBratislava 84215Slovakia Biomedical Research Center Institute of Clinical and Translational ResearchSlovak Academy of SciencesBratislava 84505Slovakia School of Nutrition Sciences Faculty of Health SciencesUniversity of OttawaOttawaON K1N 6N5Canada Department of Biochemistry Microbiology and ImmunologyFaculty of MedicineUniversity of OttawaOttawaON K1N 6N5Canada

In 2020,Kostic1 published commentary on the bacterial genus Veillonella associated with the interaction between the intestinal microbiota and skeletal *** then,novel perspectives on the bidirectional gut-muscle communication axis have gained a lot of *** purpose of this commentary is to explore some of the challenging issues presented in Scheiman et al.

关键词： skeletal gained

Products of Commutator Ideals of Some Lie-admissible Algebras

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数学学报（英文版） 2024年第8期40卷 1875-1892页

作者： ivan KAYGORODOV Farukh MASHUROV Tran Giang NAM Ze Rui ZHANG CMA-UBI Universidade da Beira InteriorCovilhãPortugal Shenzhen International Center for Mathematics(SICM) Southern University of Science and TechnologyShenzhen 518055P.R.China Institute of Mathematics VAST18 Hoang Quoc VietCau GiayHanoiVietnam School of Mathematical Sciences South China Normal UniversityGuangzhou 510631P.R.China

In this article,we mainly study the products of commutator ideals of Lie-admissible alge-bras such as Novikov algebras,bicommutative algebras,and assosymmetric *** precisely,we first study the properties of the lower central chains for Novikov algebras and bicommutative *** we show that for every Lie nilpotent Novikov algebra or Lie nilpotent bicommutative algebra A,the ideal of A generated by the set {ab-ba|a,b E A} is ***,we study prop-erties of the lower central chains for assosymmetric algebras,study the products of commutator ideals of assosymmetric algebras and show that the products of commutator ideals have a similar property as that for associative algebras.

关键词： 17A30 17B30 17D25 assosymmetric algebra bicommutative algebra Lie nilpotent algebra Novikov algebra

Interatomic Interaction Models for Magnetic Materials:Recent Advances

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Chinese Physics Letters 2024年第6期41卷 54-66页

作者： Tatiana S.Kostiuchenko Alexander V.Shapeev ivan S.Novikov Emanuel Institute of Biochemical Physics RAS 4 Kosygin StreetMoscow119334Russian Federation Independent investigator

Atomistic modeling is a widely employed theoretical method of computational materials *** has found particular utility in the study of magnetic ***,magnetic empirical interatomic potentials or spinpolarized density functional theory(DFT)served as the primary models for describing interatomic interactions in atomistic simulations of magnetic ***,in recent years,a new class of interatomic potentials known as magnetic machine-learning interatomic potentials(magnetic MLIPs)has *** MLIPs combine the computational efficiency,in terms of CPU time,of empirical potentials with the accuracy of DFT *** this review,our focus lies on providing a comprehensive summary of the interatomic interaction models developed specifically for investigating magnetic *** also delve into the various problem classes to which these models can be ***,we offer insights into the future prospects of interatomic interaction model development for the exploration of magnetic materials.

关键词： materials interaction empirical