I.V. Mikhaylov1,2, I.S. Oshlykov3, I.V. Surodina1,4, M.N. Nikitenko1, V.N. Glinskikh1,2 1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia 3Novosibirsk State Technical University, Novosibirsk, Russia 4Institute of Computational Mathematics and Mathematical Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Electromagnetic logging, toroidal coils, physical modeling, mathematical modeling, finite-difference method, geoelectric model, profiling, signal transformation
The study compares in detail the signals of an electromagnetic tool with toroidal coils which were measured in an electrolytic tank with a borehole and numerically calculated in its three-dimensional geoelectric model. For each electrical resistivity of the electrolyte, we performed the profiling of the air-tank and tank-borehole boundaries during round-trips of the tool. The values of the coupling coefficient of the measured and modeled signals have been determined for the entire set of frequencies and positions of the measuring coils in the summary and differential operating regimes. We have identified a pair of signals with a virtually constant coupling coefficient at varying electrolyte mineralization. Drawing on this pair, transformations of the tool signals into the apparent electrical resistivities of the geoenvironment have been constructed. The resulting transformation graphs allow a reliable recalculation of the measured signals of the toroidal tool into the apparent electrical resistivity distribution in the near-wellbore space, which is necessary for the petrophysical interpretation of the field log data.
A.F. Emanov1, A.A. Emanov1,2, E.V. Shevkunova1, E.A. Gladyshev1 1Altay-Sayan Branch of Geophysical Survey, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia 2Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Eastern Altai, Tsagan-Shibetu Range, Tsagan-Shibetu earthquake, aftershocks and foreshocks
The 29.07.2022 (UTC time 13:01:10.1) Tsagan-Shibetu earthquake with ML = 6.2, MW = 5.5 occurred in the eponymous mountain range in the eastern Altai Mountains (Gorny Altai), in proximity to the Tuva Basin (50.51º N, 90.69º E). The Tsagan-Shibetu Range was seismically inactive in the twentieth century, while neighboring with seismically active ones: the focal area of the 1970 Ureg-Nur earthquake with MS= 7.0 and the seismically active Shapshal Range where earthquakes with magnitude of up to five occurred quite frequently, however, no large earthquakes have hitherto been reported. Significant alterations in the structure of seismicity of Gorny Altai occurred after the 2003 Chuya earthquake with MS = 7.3: the period of quiescence was followed by emergence of new zones of enhanced seismic activity, with the Tsagan-Shibetu Range representing one of them. The internal structure of the mountain range is characterized by the formation of a triple-planed focal area with the pulse-like seismic process developing over time. The evolution of high seismicity in the considered mountain range occurred in the presence of foreshocks.
S.V. Borzenko, I.A. Komogortseva
Institute of Natural Resources, Ecology and Cryology, Siberian Branch of the Russian Academy of Sciences (INREC SB RAS), Chita, Russia.
Keywords: lakes, sulfates, sulfate reduction, evaporation, interaction of water with rock
This study analyzes the mineral and chemical composition of water and sediment, as well as the isotopic compositions of water, carbon, and oxygen in dissolved and precipitated carbonates, sulfate sulfur, and hydrogen sulfide. It has been established that the groundwater and surface water supplying saline sulfate lakes belong to the sulfate-bicarbonate geochemical type with a pH of less than 9. The research indicates that the region predominantly features soda and sulfate types of saline lakes. It has been revealed that in these types of lakes, the sulfate coefficient of the water exceeds 1, while the value of this coefficient decreases with increasing salinity due to the precipitation of thenardite and the process of sulfate reduction. It has been demonstrated that changes in the hydrochemical types of lakes lead to alterations in the mineral composition of their bottom sediments. During low-water periods, autochthonous sediment accumulation predominates, with an increased proportion of dolomite and clay minerals such as kaolinite and hydromica, while montmorillonite is additionally prominent in soda lakes. Concurrently, isotopically heavy oxygen accumulates in carbonates. Further increases in water salinity are accompanied by the precipitation of gelyusite, trona, and anhydrite, as well as a transition from soda to sulfate types. The formation of thenardite results in a shift from the sulfate to the chloride type. During the period of lake desalinization, allochthonous sedimentogenesis prevails, leading to the accumulation of clastic material in lake sediments, primarily represented by plagioclases and feldspars, alongside carbonates with an isotopically lighter composition of oxygen in the carbonates.
1Institute for Complex Analysis of Regional Problems, Far Eastern Branch of the Russian Academy of Sciences, Birobidzhan,Russia
2Hydrogeological service of JSC "Belokurikha Resort", Belokurikha, Russia
Keywords: organic matter, thermal waters, genesis, bacterial activity, hydrocarbons
The present study is aimed at the determination of organic compounds in thermal waters of the Belokurikha deposit (Altai Territory), which is important both for balneology and regional ecology. The TOC concentration ranges from 0.42 to 0.55 mg/L. Using capillary gas chromatography-mass spectrometry and solid phase extraction, 69 organic compounds were identified, forming 16 homologous series. Normal and iso-alkanes (25 %), as well as carboxylic acids and their esters (24 %) and aromatic hydrocarbons (14 %) dominate in thermal waters. The molecular weight distribution of the limiting hydrocarbons (odd/even1.3–1.5, ACL 16.6–17.5) and the presence of characteristic compounds indicate that the organic matter in the waters studied is of autochthonous, predominantly bacterial origin. A number of identified constituents may indicate a low level of anthropogenic contamination of the waters investigated (phthalates and compounds containing a tert-butyl group and chlorine). Oxygen-containing compounds may have therapeutic effects on the human body. The comparative analysis with Far Eastern hot springs showed both great similarities in the distribution of organic compounds and differences due to the contribution of plant detritus to the formation of the organic component of Far Eastern thermal waters.
The article considers the issues of determining the characteristics of target horizons using methods capable of learning on large volumes of heterogeneous data and high prediction accuracy. The methods are used to solve problems of seismic facies analysis at oil and gas fields, the main purpose of which is to reconstruct the sedimentation rocks and predict lithofacies in the study area. The object of the study was one of the fields in the Volga-Ural region. An improved Bayesian classifier was used as a tool. It was used to determine promising distribution zones of the reservoir of the productive formation B2 of the Bobrikovian deposits of the Lower Carboniferous and to assess the hydrocarbon production potential. During the research, the effectiveness of the application of machine learning methods and the proposed improvements was analyzed.
The article considers the problem of distortion of effective velocities estimated from common depth point (CDP) gathers caused by implementation of static corrections for compensation of the influence of near surface velocity anomalies. An analytical solution of the problem of compensation of effective velocities caused by the static correction for shallow and deep velocity anomalies correction is presented. The results of numerical modeling demonstrate the efficiency of the obtained solution. A comparative assessment of the accuracy of time to depth conversion with proposed methodology, without velocity correction and other algorithms for solving the problem is provided
A.A.Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian of Sciences,
Novosibirsk, Russia
Keywords: Dinoflagellate cysts, Campanian, biogeography, paleogeography, correlation
The article presents the results of the analysis of the geographical distribution and taxonomic diversity of dinoflagellate cysts in the Campanian of the Northern Hemisphere. Three types of dinocyst assemblages were established based on the qualitative and quantitative assessment of their generic composition. A wide distribution of some stratigraphically important genera and species, which previously had narrower habitats, was revealed due to transgressive events, expansion of interbasin connections, and the presence of multidirectional meridional currents. The possibility of comparing the North Siberian dinocyst assemblages with those from the stratotypes containing the orthostratigraphic faunal groups of the West European and North American Campanian deposits through the ekaton sections of the Subpolar Cis-Urals and the south of Western Siberia was shown.
A significant problem of the magnetotelluric sounding (MTS) method is the influence of local near-surface inhomogeneities, which distort MTS data across the entire frequency range. These distortions complicate the analysis and interpretation of the data and, ultimately, the retrieval of information about the studied deep structures. A widely used method for suppressing near-surface distortions is the normalization of MTS curves using spatial low-frequency filtering. The aim of the article is to evaluate the effectiveness of this approach, including through the use of weighting characteristics proposed by the authors. A simple geoelectric model of the earth's crust has been compiled, containing a conductive sedimentary cover, a high-resistivity basement, and a three-dimensional conductive depression in the basement. Two model variants were considered: with a homogeneous upper part of the section and with multiple local near-surface inhomogeneities. Using three-dimensional modeling, synthetic magnetotelluric sounding (MTS) data has been calculated for a system of profiles. The data for the second model variant exhibit the effect of near-surface distortions, which leads to a shift in the MTS amplitude curves by level. To suppress the distorting effect from near-surface inhomogeneities, we used normalization of the MTS curves with smoothing filters in a sliding window with different radiuses. Various weight characteristics of the filters were used, namely: for the distance of a point from the center of the sliding window radius, for the difference in amplitude at a given point from the average in the window, and for the difference in the principal directions determined from the polar diagrams of the modulus of the principal component of the impedance tensor and the principal component of the phase tensor. In general, the experimental results showed high efficiency of normalization of the principal components of the impedance tensor and telluric tensor and lower efficiency of normalization of additional components.
Using the laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) complex, with the involvement of X-ray photoelectron spectroscopy (XPS), new data were obtained on the distribution features and concentration levels of “invisible” gold on the natural surface of arsenopyrite crystals from the Natalka gold deposit (North-East of Russia). It was found that the distribution of Au contents on the surface of the studied sulfide and its concentration levels are closely related to the conditions of the deposit formation. The highest Au concentrations are confined to the surface of arsenopyrite crystals of the hydrothermal stage of ore formation, and the minimum ones are found at the early metamorphic stage. The extreme instability of the gold distribution profile and its content even within the surface of a single crystal is especially pronounced in arsenopyrite of vein and veinlet-vein ores, which is due to the instability of the physicochemical parameters of the hydrothermal ore formation processes at later stages of the deposit formation. Basically, these are oxidation processes that lead to a change in the composition of the primary (as-grown) non-autonomous phases and the redistribution of gold in the surface layer of the crystal, containing highly charged forms of arsenic – As5+
and As3+. The complex and long-term metamorphogenic-magmatic genesis of the giant gold ore deposit Natalka is confirmed. High concentrations of “invisible” gold in the easily destroyed surface layer of sulfides during enrichment are of significant practical interest in the extraction of gold from “refractory” ores, increasing the quality and value of the extracted raw materials.
N.V. Sennikov, O.T. Obut, N.G. Izokh, A.V. Timokhin, I.V. Korovnikov, E.V. Lykova, R.A. Khabibulina
Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Tyva, Ordovician, litho-biostratigraphy, marine sedimentary and volcanic-sedimentary strata
New lithological and biostratigraphic data on stratotype and paleontologically representative marine sedimentary sections of the Malinovka Group (Borlug, Tarlyk and Tamzyrin formations) in the Uyuk area of the region; Shemushdak Group (Ayangaty and Adyrtash formations) and Chergaky Group (Alavelyk Formation) in the Khemchik area of the region; Chergaky Group (Alavelyk Formation) in the Alash area of the region; Kargy Formation in the Kargy area of the region are discussed. The materials on the Sistigkhem Group (Uza, Ust’-Khamsary and Kugar formations) in the Sistigkhem area of Tyva are considered. The chronostratigraphic position of the Tarlag-Aksy Horizon has been clarified and the identification of a new Borlug Horizon has been substantiated. It has been found out that outrcops of the Tyva Ordovician marine sediments are currently located in the number of tectonically isolated blocks and are not fragments of a single paleobasin. Based on the analysis of the taxonomic composition of faunal assemblages and ichnofossils, it is suggested that the Tuvinian Alash-Khemchik, Uyuk and Kargy blocks with outcrops of Ordovician marine sediments were paleozoogeographically close to the marine paleobasins of the Gondwana group of continents. At the same time, a low migration potential of their faunal assemblages relatively to the possibilities of communication with coeval communities of the Altai Basin and of that of
2 из 48
the Siberian Platform and Taimyr was observed. The Tuvinian Sistigkhem block characterized by effusive-sedimentary sequences of the marine genesis was not only at a significant distance from the listed Siberian paleobasins, but was also separately located from the group of Alash-Khemchik, Uyuk and Kargy blocks with Ordovician marine sediments.
V.V. Marusin 1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences,Novosibirsk, Russia 2Novosibirsk State University,Novosibirsk, Russia
Keywords: Vendian, Cambrian, General Stratigraphic Scale of Russia, International Chronostratigraphic Chart, small skeletal fossils, trace fossils, chemostratigraphy, Siberian Platform
Nemakit-Daldynian Stage was originally introduced as a regional stage, embracing the lowermost Cambrian strata with the oldest small skeletal fossils, for the Anabar Uplift sections in the 1960s. In subsequent years, it became widespread in the works of Soviet researchers as the terminal Vendian or basal Cambrian stage or regional stage. Almost at the same time, the concept of the Manykaian Stage appeared which is close in its volume and geological meaning to the Nemakit-Daldynian Stage. Although this unit plays a crucial role for our understanding of the chronology of biotic turnovers at the Vendian–Cambrian transition, its status, age, and correlation with the Manykai Stage and units of the International Chronostratigraphic Chart (ICC) remain unclear. This research reveals a historical background revisits the stratigraphic volume and age of the Nemakit-Daldynian Stage. The integrated biostratographic, stable isotope and geochronological data shows this unit belongs to the Upper Vendian and spans the interval from the first appearance of unequivocal anabaritids (~539 Ma) to the first appearance of the Tommotian small skeletal fossils (~530 Ma). In this interpretation, the Nemakit-Daldynian Stage corresponds to the Fortunian Stage of the Cambrian System in the ICC. The base of this unit is coeval to the base of the Rovno Regional Stage of Baltica.
This paper presents the results of experiments to strengthen the surface of a fluoroplastic composite by creating a protective layer. The protective layer was formed by detonation spraying of VSNGN-85 powder consisting mainly of WC (81.56 wt.%) and Ni (10.6 wt.%). The granulometric and morphological properties of VSNGN-85 powder were studied, and its X-ray diffraction analysis was carried out. Optimal spraying modes for obtaining a dense coating 100÷115 mu thick were selected. X-ray diffraction analysis showed the presence of WO3 tungsten oxide and NiWO4(II) nickel tungstate in the coatings. The microhardness of the composite material with the protective coating was found to be 48 times higher than the microhardness of the composite without coating. The applied coating increases the life of the fluoroplastic composite, improves its strength, and slows down the processes of its oxidation, corrosion, and thermal destruction.
E.I. Palchikov1,2 1Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Science, Novosibirsk, Russia 2Novosibirsk National Research State University, Novosibirsk, Russia
Keywords: explosive emission, fracture, high electric fields in vacuum, ion and electron bombardment
Fracture of the electrodes of a three-electrode pulsed X-ray tube with a rechargeable insulated electrode operating in explosive emission mode at a voltage of 600 kV and pulsed current up to 1000 A was investigated. The fracture was produced by the action of high pulsed electric fields and pulsed flows of electrons and plasma during vacuum breakdown in X-ray tubes. X-ray fluorescence microanalysis using a scanning microscope revealed the presence of numerous metal globules of size 10÷40 mu formed from both the tungsten anode material and the material of the third insulated Kovar electrode. Several stages of separation of the globules by the electric field were detected on the insulated electrode. Quantitative estimates for the critical values of Coulomb forces at which droplets arise were obtained in accordance with a dynamic model (taking into account the kinetic energy accumulated by the mass during the exposure to the electric field and surface energy), and the electric field pressures during the operation of the tube were estimated, allowing an explanation of the observed phenomena.
Results of experimental and numerical simulations of interaction of plane shock waves with gas-permeable cellular-porous targets are presented. Some of these targets are homogeneous over the thickness, while others consist of material layers with pores of different diameters. The experiments are performed in a shock tunnel in the range of the shock wave Mach numbers M=1,2÷1,8. High-porosity cellular nickel is chosen as a gas-permeable material. In numerical simulations, such cellular-porous materials are described by a toroidal model of a porous medium. The mechanism of formation of reflected shock waves is revealed. The intensity of waves reflected directly from the structural elements of the material and of waves reflected from the rear end face of the wind tunnel is shown to be lower in the presence of targets made of a gas-permeable high-porosity cellular material. The most effectively reflected waves are suppressed by combined targets composed of material layers with pores of different diameters.
N.K. Luzgin1,2, A.A. Sidorenko1, A.D. Budovskii1, O.A. Gobyzov3 1Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State Technical University, Novosibirsk, Russia 3Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: transonic flow, shock wave/boundary layer interaction, luminescent pressure transducers, numerical simulation, flow separation
Interaction of a shock wave with the boundary layer on a half-airfoil model is studied. The experiments are performed in a wind tunnel with the free-stream Mach number M ≈ 0.75 and stagnation pressure P0 = 105 Pa. The half-airfoil model is mounted on the wall of the test section of the wind tunnel. Pressure distributions over the model surface are obtained by a method with luminescent pressure transducers and by a method with pressure taps. The limiting streamlines on the model are visualized, and thermographic visualization is also performed. For experimental parameters, numerical simulations are performed with an approach based on using the Reynolds-averaged Navier--Stokes equations. The three-dimensional structure of the flow is analyzed, and significant differences in the measured and simulated results for the flow in corner separation regions are revealed.
A.I. Kutepova, D.V. Khotyanovsky, A.A. Sidorenko
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: direct numerical simulation, interaction of the shock wave with a laminar boundary layer, flow separation, heat source of disturbances
Direct numerical simulations of propagation of disturbances generated by a heat source in a supersonic boundary layer interacting with an oblique shock wave are performed by the HyCFS-R hybrid code. The processes of excitation and evolution of unstable disturbances in the boundary layer, the influence of the incident shock wave on evolution of disturbances, and also the effect of disturbances on boundary layer separation and flow development in the separation region and in the laminar-turbulent transition region are studied. The influence of the duration of the thermal pulse on excitation and development of unstable waves in the boundary layer and interaction region is investigated. A case of disturbance generation by a pair of sources located at a certain distance from each other is considered. It is shown that reduction of the heat pulse duration leads to enhancement of the amplitudes of the first and second harmonics of the main unstable mode. For this reason, the disturbance spectrum in the interaction region changes, and flow turbulization is accelerated, which leads to reduction of the separation region size.
K.K. Maevskii
Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: equation of state, shock Hugoniot, phase transition, calcite
The behavior of calcite at pressures up to 1000 GPa is simulated taking into account the high-pressure phase transition. The shock-wave loading of calcite was calculated using a thermodynamically equilibrium model. A few-parameter equation of state of the Mie--Gruneisen type is used to describe the behavior of condensed phases. In the phase-transition region, the components of the sample under study are considered as a mixture of low- and high-pressure phases. The shock Hugoniots of single and double compression are constructed in the pressure range from 1 to 1000 GPa, and the heat capacity along the normal isobar, entropy as a function of temperature, and the thermodynamic potential along the shock Hugoniots were calculated. The simulation results were verified against experimental data and available calculation results
A. I. Rudenko
Kaliningrad State Technical University, Kaliningrad, Russia
Keywords: stationary weakly nonlinear periodic wave, potential fluid motion, wave profile, stream function trace, first Stokes method
A two-dimensional problem of stationary nonlinear waves on the surface of a layer of finite-thickness ideal fluid is considered. The solution to the problem using the proposed technique includes the following steps. Firstly, the stream function trace is used to change the kinematic condition on the free surface. Secondly, the Bernoulli---Cauchy integral is applied to present the dynamic condition in a new form. Thirdly, an integral operator of the convolution type is introduced, which allows one to simplify the nonlinear boundary value problem of determining four functions of one variable, the main ones of which are a wave profile shape and a stream function trace at the zero horizon. This technique allows reducing the two-dimensional problem to a one-dimensional one. Two forms of the nonlinear dispersion relation are obtained: the dependence of the wave velocity on the amplitude of the fundamental harmonic of the wave and the dependence of the wave velocity on the wave amplitude. The cases of short and long waves are considered
R. Abazari1, K. Yildirim2 1Department of Mathematics, University of Mohaghegh Ardabili, Ardabil, Iran 2Mus Alparslan University, Mus, Turkey
Keywords: small Phase separation, Cahn--Hilliard model, Splitting scheme, Crank--Nicolson method, Error estimation
In this paper, we have approximated the solutions of the Cahn-Hilliard equation (CH) with the logarithmic potential function which arises in the modeling of phase separation of binary alloys. The CH equation is a high-order nonlinear equation,consequently, utilizing a common difference scheme on the CH equation causes long stencil schemes. To resolve the faults of long stencil schemes, we split the CH equation to a second-order system under the Neumann boundary condition and we applied a second-order scheme based on the 2D Crank-Nicolson method to discrete it. The uniqueness and error estimation of the approximated solution is proved. Also, preserving the conservation of mass and decreasing the total energy are investigated. Finally, to confirm the theoretical results, three examples with various initial conditions are presented.
I. M. Ilyukhin, I. V. Egorov
Moscow Institute of Physics and Technology, Zhukovsky, Russia Central Aerohydrodynamic Institute, Zhukovsky, Russia
Keywords: numerical simulation, supersonic boundary layer, laminar-turbulent transition, favorable pressure gradient, turbulent spot
Perturbation propagation in a supersonic boundary layer on a straight parabolic wing is numerically simulated. Near the leading edge, a mass flow rate perturbation is introduced into the boundary layer, resulting in the formation of a first-mode wave packet, and the amplitude of the first mode increases downstream. It is shown that, upon reaching a critical amplitude, the perturbation begins developing nonlinearly and longitudinal structures appear. The nonlinear interaction of the boundary layer modes leads to the formation of a turbulent spot. The characteristics of the resulting spot with known data for gradient-free flows are compared
A. A. Rakhimov, D. A. Samigullin
Mavlyutov Institute of Mechanics, Ufa Federal Research Centre of the Russian Academy of Sciences, Ufa, Russia
Keywords: honey, air bubble, rheology, viscosity, shear strain rate, surface tension
The properties of honey are studied experimentally.It is shown that the viscosity of honey decreases with an increase in its moisture content or temperature. Close results are obtained when measuring the surface tension coefficient of white honey using several methods: the drop weight method, the capillary ascent, and the detachment by an air bubble in a liquid. A formula is derivedthat allows one to estimate the dynamic viscosity of the liquid usingthe known surface tension coefficient and the known rate of recovery of an air bubble shape in a liquid after the bubble was stretched twice its size at the same measurement temperature
V. A. Arkhipov, S. Yu. Bogdanov, A. S. Usanina, R. A. Churkin
National Research Tomsk State University, Tomsk, Russia
Keywords: monodisperse droplet cluster, droplet concentration, rate of ascent, experimental study
The paper describes an experimental study of the process in which a cluster of monodisperse droplets of isoparaffin oil ascends to the surface in distilled water in a range of Reynolds numbers Re = 200÷800. It is shown that the initial volume concentration of droplets in the cluster is one of the main parameters determining its dynamics. The study also touches upon the motion of two types of clusters, characterized by the presence or absence of collisions of the droplets contained in it. Experimental dependences of the rate of ascent of the droplet cluster on the Reynolds number are obtained for different values of the initial volume concentration of droplets. The limiting value of the initial volume concentration of droplets is determined, corresponding to the onset of cluster motion with a velocity exceeding the velocity of a single droplet
P. N. Kazantsev, B. L. Smorodin
Perm State National Research University, Perm, Russia
Keywords: magnetic fluid, magnetophoresis, thermal diffusion, convective stability, Hele---Shaw cell, Galerkin method
This paper touches upon the formation of thermomagnetic convection in a stratified magnetic colloid filling a Hele---Shaw cell placed in an external nonuniform magnetic field and heated from the side of a narrow edge in such a way that the constant field strength gradient is co-directed with the temperature gradient. The Galerkin method is applied to obtain critical magnetic Rayleigh numbers for the cases of monotonic convection and oscillatory convection arising due to the nonuniformity of the concentration of magnetic nanoparticles caused by thermal diffusion and magnetophoresis. In the case of oscillatory instability, the dependence of the neutral oscillation frequency on the mixture separation parameter and the concentration Rayleigh number is determined. For supercritical monotonic and oscillatory convection conditions, the current function, temperature, and concentration distributions are presented, and the behavior of the amplitudes of various spatial harmonics is investigated
V.I. Borodulin, A.V. Ivanov, Y.S. Kachanov, A.P. Roshchektaev
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: swept-wing boundary layer, cylindrical trip devices, scenarios of the transition to turbulence, efficiency of trip devices
The main goal of the present study is to investigate the mechanism of forced turbulization of the laminar boundary layer on a swept wing with domination of crossflow instability by means of using spanwise-periodic cylindrical trip devices. The experiments are performed with hot-wire anemometry in a low-turbulence wind tunnel based at the Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk) at low subsonic free-stream velocities; a 25-degree swept wing is chosen as a model. Results of detailed precision measurements of the mean and fluctuating structure of the flow are obtained in a broad space range in 12 different regimes of measurements for five types of trip devices (and also without them) for two flow velocities. The range of the Reynolds numbers based on the trip height is from 565 and 3613. The present paper describes the first part of the study, i.e., the main scenarios of the transition to turbulence induced by trip devices. They are demonstrated to be highly effective. Subsequent studies will be described in Part 2 of the paper.
A.V. Boiko, A.V. Dovgal, A.M. Sorokin
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: hydrodynamic stability, boundary layer separation, flow past a backward-facing step, unsteady flow
An incompressible gas flow past a two-dimensional backward-facing step on the flat plate surface is experimentally studied under the conditions of a controlled low-frequency action on the separated flow. It is found that flow oscillations whose frequency is smaller by an order of magnitude than the frequency typical for convective instability of the separated boundary layer induce significant changes of the time-averaged and fluctuating characteristics of the flow in the separation region.
A. V. Ivanov, A. D. Cherepanov
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Keywords: aerodynamics, cycloidal rotor, propeller, aircraft, controlled thrust vector
A history of development of various cycloidal rotors used as aircraft propellers is presented. The operating principle of a cycloidal rotor with a swinging blade is described. Differentpapers on this issue are reviewed, quantitative data are summarized and analyzed, and the most important parameters affecting the characteristics of a cycloidal rotor with a swinging blade are identified. Optimal values of the main parameters for improving the characteristics of a CR with a swinging blade are obtained. A method for the engineering evaluation of the thrustof a cycloidal rotor with a swinging blade is proposed
D.V. Dik, A.A. Filippov, N.Yu. Burkhinova
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: boron carbide, chromium diboride, nanofiber carbon, hot pressing, microhardness, elastic modulus}
Functionally graded B4C-CrB2 material with a CrB2 concentration gradient along the thickness equal to 5, 15, and 25 % was produced by reactive hot pressing of a mixture of boron carbide, chromium oxide, and a carbon material with high specific surface area. A general view of the microstructure and the size distribution of chromium diboride particles in each layer are presented. The change in mechanical properties with an increase in the CrB2 concentration is shown to be non-monotonic due to the features of boron carbide reduction.
This paper presents an algorithm for the developed overdetermined method of constructing the asymptotics of the stress field near a nanocrack tip in an anisotropic linear elastic body with cubic symmetry. For the problem of combined loading (normal separation and transverse shear) of a nanoplate of monocrystalline copper and aluminum with a central cut, a molecular dynamics solution was obtained and used to derive an asymptotic representation for the stress tensor components. The atomistic stresses in the vicinity of the crack tip were calculated, and the coefficients of the series representing the stress field were determined using the values of the atomistic stress tensor components. The molecular dynamics calculations were performed for a temperature of~10~K to exclude the appearance of a zone of nonlinear elastic deformation near the crack tip. The stress fields in the atomistic and analytical solutions were compared. The stresses at different distances from the nanocrack tip are in good agreement with the solutions of problems of macroscopic classical theory of anisotropic elasticity and can be described using a series that extends the Williams series to anisotropic media. In the series extended to anisotropic materials, the regular (non-singular) terms were taken into account and the series coefficients of these terms were determined. It is shown that the developed algorithm can be used to effectively determine the coefficients of the higher-order terms of the series
E.V. Karpov1,2, A.N. Prokhorov1,3, A.Yu. Larichkin1,2, V.N. Goverdovskiy1 1Moscow Polytechnic University, Moscow, Russia 2Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 3Tyubol Tsentr NSK, Novosibirsk, Russia
Keywords: thin-walled structures, supercritical deformation, elastic element of quasi-zero stiffness, infrafrequency vibration, vibration isolation
An approach to the simulation and evaluation of the parameters of thin elastic open shells and plates under postcritical deformation is proposed. A finite element model of the longitudinal bending of a plate with a trough-shaped profile is considered. A numerical simulation of the behavior of a plate with quasi-zero stiffness was performed, and the effectiveness of such a plate as an elastic element of a vibration isolation mechanism was studied. Finite element simulation results were compared with the results of calculations using analytical models and with experimental data. The possibilities of adjusting the quasi-zero stiffness of plates were analyzed. The results obtained indicate that such elastic elements can be widely used in vibration isolation systems for ground and onboard equipment
S. Lamsadfa1, M. Amara2, A. Belalia2, M. Hadj Meliani1,3, G. Pluvinage2, G.Y. Matvienko4 1University of Tamanghasset, Tamanghasset, Algeria 2University Hassiba Benbouali of Chlef, Chlef, Algeria 3LEM3-Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux-ENIM, Metz, France 4Mechanical Engineering Research Institute. Russian Academy of Sciences, Moscow, Russia
Keywords: fracture assessment, Material Failure Curve, notch driving force, API 5L pipe
The assessment of material toughness is governed by codes based largely on rigorous experimental results. However, the problem of transferability from the laboratory specimen to field-scale structures limits the extent to which these results can be used. The present work is a developmental contribution to a new approach for assessing the toughness of pipeline steels. The procedure concerns the interaction between material fracture curve based on the three-parameter fracture criterion (K-T-A3) and the surface longitudinal notch driving force of a pipe under internal pressure. This could be applied as an important engineering parameter for assessing the structural integrity of pipelines during long-term operation.
V.V. Vasil'ev1,2, S.A. Lurie2, V.A. Salov1,2 1Central Research Institute of Special Machine Building, Khot'kovo, Russia vvvas@dol.ru 2Institute of Applied Mechanics, Russian Academy of Sciences, Moscow, Russia salurie@mail.ru
Keywords: unsteady problem of heat conduction, differential calculus, nonlocal functions
An unsteady problem of heat conduction for a rod is considered. The classical heat conduction equation based on the assumption of temperature differentiability with respect to time and coordinate is derived. A solution of a model problem with boundary conditions of the second kind is obtained, which determines the temperature distribution in the thermally insulated rod over its length and in time. For the classical formulation of the problem, the temperature change rate at the initial time is found to be singular, and the condition of temperature differentiability with respect to time is not satisfied. A modified form of the heat conduction equation is proposed, which is based on nonlocal determination of temperature as a time-dependent function. In contrast to the traditional definition of temperature, this function is not the temperature value at a fixed time; instead, it is the mean value on a finite time interval called the nonlocal temperature. As a result of using such an approach, the heat conduction equation retains the classical form, but contains the nonlocal temperature rather than the traditionally used temperature. Traditionally, the temperature is determined by means of solving the Helmholtz equation including an unknown time interval over which the temperature is averaged and which is determined experimentally. The classical and nonlocal solutions are compared with experimental data. The nonclassical Maxwell--Cattaneo equation of heat conduction is discussed, which implies a finite rate of temperature propagation in time.
A.G. Megrabov1,2 1Institute of Computational Mathematics and Mathematical Geophysics Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: family of curves, curvature vector of a vector field and its vector potential, associated vector field, degree of nonholonomy, Aminov's divergent representations, conservation laws
A number of new formulas are obtained for vector fields and vector analysis used in geometry and the vector field characteristics used in differential geometry: curvature vector, associated vector field, degree of nonholonomy, and the Laplacian value. Non-classical characteristics such as the vector potential of the curvature vector field of a vector field and the sum of three curvature vectors of vector lines of the Frenet unit vector fields of a family of curves are also studied. It is shown that all the listed quantities are related to Aminov's divergent representations for the Gaussian curvature or for the total curvature of the second kind. The obtained formulas can be considered as properties of the family of curves. Some formulas have divergence form, which makes it possible to derive differential conservation laws for the family of curves as well as for the eikonal equation and Euler's hydrodynamic equations
A.K. CHERKASHIN
V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Keywords: geographical systems, definition of concepts, intertheories of modeling, geosystem analysis, functional and geomeric models, territory of Baikal Siberia
The achievements and problems of the V.B. Sochava’s geosystem doctrine, its spread abroad and development towards the joint use of conceptual, statistical and mathematical analysis in geography are discussed. The doctrine is considered in the context of the general systems theory and the possibility of applying other intertheories that explain the properties of nature, economy and population of a territory in unified system terms. The basic concept is a “structure” that imposes a system order on a set of elements to ensure their organization and functioning. Geosystems differ in the type of intertheoretical description of elements and their relationships - complex, functional, dynamic, behavioral, classificational, etc., as well as in the form of expression: natural and integral geosystems, metasystems, monosystems, polysystems, geocomplexes, episystems, chorions, and holаsystems. Their properties are reflected by special mathematical formulas of differential geometry of layered spaces. In particular, holаsystems of integrity are described as structures of surfaces defined by continuous functions (manifolds), enveloping in these spaces the planes of functions of a set of adjacent monosystem layers (geomeres) and thereby determining their pairwise connectivity and territorial organization of polysystems (geochores) in the unity of the geographical environment. Different types of geosystems are considered only as subjects, not objects of geographical research, which makes it possible to choose specific directions, models and methods for solving scientific problems. Formalization of accumulated geosystem knowledge is supported by conceptual schemes in the form of graphs and charts, and materials of statistical processing of primary and cartometric data. V.B. Sochava set the task of creating a functional-geomeric model to reflect the importance of geomers in the structure of geochores. It is proposed to discuss this problem in terms of the ordinal intertheory of describing the distribution of geoms by significance (occurrence) in different physical-geographical regions of Baikal Siberia. It is assumed that the same problem is solved by means of different intertheories using the appropriate mathematical apparatus. The development of such research tools corresponds to different directions of improving the geosystem analysis methods.
The analysis of various types of islands occurring on rivers with a branched channel or on meandering rivers was carried out, which made it possible to classify the islands taking into account the features of their formation, development and dynamics, as well as depending on the characteristics of the channel itself. Six main categories of islands have been identified, associated with their characteristics and conditioned by genesis, position in the channel, compliance with a particular structural level of branching, shape in plan (hydraulic resistance exerted by the island on the flow), and age. In addition to the main factors, the classification of islands is influenced by the characteristics of the channel itself, among which we can note its widening (the formation of an island in local widenings of the channel or due to the splitting of the flow into two or more branches of the current), stability, which determines the size and number of islands in each branching node, which, in turn, is directly related to the dispersion of the flow along the branches. Separately identified are the types of islands formed by sand or pebble-boulder deposits, differing in the degree of resistance to the impact of the flow (intensity of erosion of the headland) and in the development of the floodplain facies of alluvium and floodplain soils, which determines the type and nature of vegetation on the island. The considered classification features take into account the main function of the islands, such as flow dispersion, and can be applied when considering the water transport use of rivers.
A.G. DRUZHININ1,2 1Southern Federal University, Rostov-on-Don, Russia 2Institute of Geography, Russian Academy of Sciences, Moscow, Russia
Keywords: spatial structures, socio-economic development, southern vector, global changes, Great South of Russia, Russia
Multidimensional global changes are projected onto Russia and its regions, initiating priority attention to the problems of spatial development. The purpose of the article is to form systemic ideas about the South of Russia as one of the key and most dynamic macroregions of the Russian Federation, about prolonged trends and current problem situations of the implementation of the “southern vector” of the spatial socio-economic dynamics of the country, and about the strategic priorities of the South Russian regionogenesis and its new (“large”) formats. Priority attention is paid, in particular, to the long-term trend of the “flow” of the population to the South of Russia and the transformation of its ethnic structure. The “wave-like” dynamics of population growth in the South Russian macroregion has been identified; it is related to its position in the center-periphery system of the country, as well as ethnodemographic and geopolitical circumstances. The article shows the socio-geographical specificity of the South of Russia that developed in the post-Soviet period and is transforming in the “post-Crimean” conditions (polyethnicity, coastalness, near-border location, comparative agroclimatic and recreational “southernness”, stability of the residential structure, etc.), as well as its functionality on a nationwide scale (agricultural-industrial, residential-recreational, transport-logistics, and military-geostrategic). The current megatrends in the natural-economic and ethnocultural spheres inherent in the South Russian macroregion are characterized. It is emphasized that the deepening stratification of the South Russian space (including under the influence of ethnodemographic processes at the regional and municipal levels) and its development as a whole according to the polycentric model are combined with the accelerated formation (due to changes in geopolitics, transport infrastructure, economic sphere) of interregional, transboundary aqua-territorial integrity - the Great South of Russia.
S.V. KAKAREKA1, T.I. KUKHARCHYK1, S.YU. TARASENKO2, K.O. RABYCHIN1, N.E. SOSNOVSKAYA1, E.V. KORZUN3 1Institute of Nature Management of the National Academy of Sciences of Belarus, Minsk, Belarus 2Arctic and Antarctic Research Institute, Saint Petersburg, Russia 3Scientific and Practical Center of the National Academy of Sciences of Belarus for Bioresources, Minsk, Belarus
Keywords: Antarctic oases, buildings, vehicles, paint coatings, corrosion
The article presents the results of the study of the heavy metal content in soil and paint samples collected at the Belarusian (“Mount Vechernyaya”) and a number of Russian scientific stations (“Bellingshausen”, “Mirny”, “Progress”, “Novolazarevskaya”) and field bases (“Molodezhnaya”, “Druzhnaya-4”). The studies were carried out in the summer Antarctic seasons of 2021/22 and 2022/23. Paint samples were collected from old painted surfaces of buildings/infrastructure elements and abandoned vehicles. Soil samples were collected near buildings from a depth of 0-10 or 0-15 cm. The content of heavy metals (Cd, Cr, Cu, Pb, Ni, Zn) in solid substrate samples was determined using atomic absorption spectrometry. It was found that the content of lead in previously used paints in 76 % of cases, zinc in 60 % of cases, and chromium in 47 % of cases exceeded 1000 mg/kg of dry matter. High concentrations of cadmium (more than 10 mg/kg) were recorded in 20 % of cases. A wide range of measured concentrations of most heavy metals was revealed in soil samples near painted surfaces, with the maximum recorded lead content. The condition of painted surfaces at the research stations, destruction of coatings, and paint removal by strong winds are discussed. It is shown that local high concentrations of heavy metals in Antarctic soils (“hot spots”) can be caused by their leaching from painted surfaces and dispersion of paint fragments. The need for special studies to quantitatively assess the impact of paint coatings on the content of heavy metals in the soils of Antarctic oases is substantiated.
The article is concerned with the study of the influence of the herbaceous vegetation cover of terrestrial and aquatic facies on the cycle of ore and associated chemical elements near the site of Cu-Zn pyrite deposit development and Cu concentrate production (Southern Urals, north of the steppe zone, Republic of Bashkortostan). Thirty-five test plots were studied, 106 samples of total cuttings, 118 soil samples, 38 reed samples, and 38 bottom sediment samples were processed. Correlation and regression analysis of the Cu, Zn, Fe, Mn, Ni, Pb, Cd, Co, Cr, Ca, Sr, Ba, V, Sc, and Sb content in total cuttings, reed samples, soil and bottom sediments was carried out. The content of individual forms of chemical elements in the soil was determined by the sequential extraction method. The reserves of elements in total cuttings, the humus soil horizon (total reserve and the reserve of three mobile fractions), and reed beds were calculated. The volume of Cu, Zn, and Cd input with dump drainage waters was estimated. The role of reed beds as a geochemical barrier in a polluted small river was revealed. Arguments were obtained in favor of a weak stabilizing effect of grass stand on the Cu and Zn reserve in the soil; the Cu and Zn contents in cuttings are interrelated, despite the variability of the abundance of different plant species; they also do not correlate with the contents of these elements (both total and mobile forms) in the soil. A hypothesis is substantiated that excessive grazing (or other mechanical impact) near mining facilities can lead to an increase in the abundance of metal-concentrating species, due to which both the concentration and the Cd reserve in cuttings significantly increase. It was found that in the studied river reed beds can act as a biogenic geochemical barrier for Cu (but not for Zn or Cd). Suggestions for increasing the barrier efficiency are presented.
S.F. SHAYAKHMETOV, V.S. RUKAVISHNIKOV, O.M. ZHURBA, A.V. MERINOV, A.N. ALEKSEENKO
East Siberian Institute of Medical and Ecological Research, Angarsk, Russia
Keywords: snow cover, soils, accumulation of chemical elements, functional zones, territories of accumulated damage, atomic absorption spectrometry
The regional problem of pollution of the natural environment components with heavy metals in the territory of accumulated environmental damage of the arsenic and battery plants in Svirsk (Irkutsk oblast) has been investigated. The analysis and assessment of the levels of content and distribution of mobile forms of polluting elements in the snow cover and soils in the industrial, residential and recreational zones of the city territory have been carried out. The following indicators were used for the ecological and hygienic assessment of pollution of the snow and soil covers: the coefficient of concentration and accumulation of chemical elements, the total pollution index, and the degree of chemical pollution. It has been established that within the considered functional zones of the urbanized territory of the city there have been observed increased levels of accumulation of mobile forms of heavy metals in the components of the natural environment, caused by the impact of emissions from industrial enterprises, a thermal power plant, household furnaces, and accumulated harmful waste from former enterprises. The accumulation of elements is manifested to the greatest extent for cadmium, manganese, zinc, and lead in snow, and for arsenic, zinc, chromium, and lead in soils. A comparatively lower level of soil pollution with heavy metals is noted in the city territory after the environmental rehabilitation of the accumulated waste of the Angarsk metallurgical plant. Direct and inverse correlations have been found between the content of elements in the snow cover and soils, indicating a high environmental significance of the impact of technogenic factors and increased migration capacity of mobile forms of cadmium, zinc and manganese in the “soil cover-adjacent environments” system. According to the total pollution index, the category of snow cover pollution corresponds to a low level, while the category of soil pollution ranges from a hazardous level in the multi-story residential sector and recreational area to an extremely hazardous one in industrial and low-rise residential zones. The degree of urban soil pollution increases in the following order: multi-story residential area < coastal forest area < low-rise residential sector < industrial zone.
O.I. BAZHENOVA1, E.M. TYUMENTSEVA2 1V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia 2Irkutsk State University, Irkutsk, Russia
Keywords: modern rift zone, intra-secular cyclicity, mudflows, sediment runoff, coastal erosion, landslides, aeolian migration of matter
The article considers the regular patterns of exogenous processes manifestation in the Baikal basin, established on the basis of monitoring data of their long-term dynamics. The analysis is based on an extensive database obtained on the western, southern and eastern shores of Lake Baikal. The research methods included experimental observations (runoff sites, benchmark method, dust collectors, etc.) on representative sites, interpretation of space images, and aerial photography from remotely piloted aircrafts. The main attention is paid to such characteristics as the rate of processes, direction and volume of transported matter as a result of mudflows, landslides, coastal abrasion, and the activity of water and wind flows. The article shows temporal organization of exogenous processes, expressed in a pronounced rhythmicity of their course, controlled by changes in secular and intra-secular cycles of water content in Lake Baikal. It is established that low-water periods are characterized by high intensity of aeolian migration of matter. Detailed observations during the last low-water period recorded its average value of 500 g/m2. During high-water periods, erosion processes are active, mudflows and landslides are recorded, and shore erosion occurs. Intensive mudflows were recorded in 1930-1938, 1960-1962, and 1968-1972, with a maximum in 1971, when the total volume of drift from the slopes along the river valleys between the towns of Baikalsk and Slyudyanka amounted to more than 1 million m3 of loose rock. The results obtained make it possible to predict the further course of processes and minimize the negative consequences of their manifestation.
N.V. KICHIGINA1, A.A. RYBCHENKO1,2, A.A. YURYEV1,2 1V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia 2Institute of the Earth’s Crust, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Keywords: mudflows, rainfall floods, flood-forming precipitation, water level, mountain rivers, Slyudyansky district
The main hydroclimatic factors of rainfall and mud flood formation have been studied, and the spatial distribution of flood hazard of various genesis has been determined within the territory of the Slyudyansky district of Irkutsk oblast. The maximum water levels at six hydroposts of the Roshydromet network for 2001-2022 have been analyzed. All flood cases with the excess of critical levels corresponding to the onset of flooding have been identified. Flood-forming precipitation and atmospheric circulation features have been assessed for years with floods. It has been determined that the greatest danger is posed by rainfall and mud floods in the Khamar-Daban estuary zone. Mudflow processes are most developed here, and the towns of Slyudyanka and Baikalsk, as well as the sludge storage facilities of the closed Baikal Pulp and Paper Mill, are at risk. In the 2001-2022 period, floods were recorded at three hydroposts in 2001, 2005 and 2019. The floods in 2001 and 2019 were of rainfall genesis, and in 2005 - mixed snow and rain. Extreme precipitation (up to 200 mm per day or more, according to the Khamar-Daban weather station), along with previous humidification of the territory during the meridional circulation of the atmosphere, are the main factors in the formation of rainfall floods and mudflows here. Foothill weather stations reflect the climate of only the coastal strip. The most representative data for a significant part of the river basins are the data of the high-mountain (1442 m above sea level) Khamar-Daban weather station, where almost twice as much precipitation falls as in the foothill territory. This difference in the amount of precipitation is not taken into account when analyzing observation data from weather stations located in the foothill territories. Therefore, for mountain catchments, it is important to create an observation network in high-mountain areas where rain floods and mudflows are formed, especially where settlements are located in the foothills.
