Home – Home – Jornals – Thermophysics and Aeromechanics 2025 number 1

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.

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.

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.

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.

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 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

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.

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

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

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

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

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.

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 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

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

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

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.

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 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

The analysis of the efficiency of turbulent boundary-layer control on low-speed airfoils using mass transfer through a permeable wall is presented. Particular attention is paid to the consideration of the physical properties of the wall flow in the presence of positive (from the wall) and negative (to the wall) mass transfer and the aero-dynamic characteristics of airfoils under conditions of distributed or localized action of mass transfer of varying intensity on the boundary layer.

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.

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.

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.

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.

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.

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.

The forests of southern Buryatia are mainly represented by communities of the formations of grass light coniferous pine forests (Pinus sylvestris L. ) and forb-grass larch forests (Larix sibirica Ledeb. ), the grass stand composition of which is characterized by wormwoods known as medicinal. In the forest communities of southern Priselenginskaya Buryatia, 14 species of wormwood have been identified; they are rich in essential oils and other biologically active substances (BAS). It has been established that wormwoods were widely used by the aboriginal ethnic groups of Siberia - Evenks, Soyots, Buryats - in religious ceremonies, and as fodder, spicy-aromatic and medicinal plants. It has been determined that, depending on the ecological characteristics of the species, their assignment to forest types (associations) may be different; the occurrence of xerophytic wormwoods will be high in pine forests, in contrast to more humid mesophytic and xeromesophytic species, which are predominantly characteristic of larch forest communities (Artemisia latifolia Ledeb., A. tanacetifolia Bieb. ). For example, of the variety of wormwoods of the subgenus of true or typical wormwoods (subgenus Artemisia L. ), the most widespread is Gmelin’s wormwood (Artemisia gmelinii Weber ex Stechm. ), characteristic not only of forb pine forest communities (spiraea-forb and sedge-forb), but also of larch forest cenoses (steppe-forb and spiraea forb-reed grass). Many species of wormwood were widely used in folk and traditional medicine - Arabic, Tibetan, Mongolian and others. It is known that these plants produce flavonoids, coumarins, and carotenoids. It has been established that they are extremely rich in essential oils, and the predominant components include camphene, alpha-pinene, beta-pinene, gamma-terpinene, and borneol. Their diversity is indicated by the oil components in the Buryat populations of Artemisia sericea (Artemisia sericea Weber ex Stechm. ), where a high percentage of the following compounds is noted: 1,8-cineole, camphor, bornyl acetate and germacren D. Wormwood has anti-inflammatory, antibacterial, antimicrobial and antioxidant effects. Further phytochemical studies of wormwood are needed to identify valuable plant species in terms of metabolites richness; they are an important resource in the search for new medicinal plants.

The article presents the results of a comprehensive geomorphological and paleogeographic study of the central part of the Oka Plateau (Eastern Sayan). The relief structure of the region is characterized in detail. A special place in it is occupied by elements of the paleohydronetwork - basins of drained moraine-dammed reservoirs and abandoned fragments of valleys, including tiered ones. A comprehensive record was obtained from the bottom sediments of Lake Sagan-Nur, which made it possible to reconstruct a consistent picture of changes in the natural environment in the lake basin in the Holocene. It is shown that in the period of about 8600-7100 years ago the lake was fed by glaciers, large flood events occurred in its basin, the water level in the lake was higher than today, and it was probably connected to a moraine-dammed paleo-reservoir, traces of which are recorded in the estuary part of the Aynak River valley. Later, about 7100-5500 years ago, a sharp drop in the rate of lacustrine sedimentation and a gradual attenuation of the relative amplitude of flood events occurred. After 5500 years ago, the warming of the regional climate, especially in winter, and the disappearance of the “remnants” of the late Pleistocene glaciers caused a gradual expansion of dry areas at lower hypsometric levels favorable for the regional development of pine forests and the rise of the upper boundary of pine on the slopes. At the end of this time interval, the last restructuring of the local hydrographic network occurred and the modern river system was finally formed. Reconstructions for the period of the last 5500 years show a much calmer hydrological regime and sedimentation pattern. Palynological indices also suggest a warming of the regional climate and a decrease in soil moisture, which took place following a change in the influx of solar radiation in the temperate latitudes of the Northern hemisphere.

The article presents data from the long-term studies of the direction of forest formation on the burnt sites of different territorial (and topological) allocation in some areas of the Baikal region. Current trends in the initial stages of forest coenoses formation, and their structure on burnt sites of different years and intensity are shown. It is noted that secondary forests consisting of small-leaved tree species, represented by their sparse undergrowth and clump young growth, are developing on the site of burnt primary coniferous taiga. Tree species are often represented by single specimens on the sites of complete destruction of edaphic conditions - underlays and upper soil horizon on mountain slopes of different orography. It has been established that on the sites of catastrophic burning (in the central part and northern regions of Western Transbaikalia) with completely burnt forest stand and underwood, including the upper soil horizon, no plant species have been found for several years. At the same time, further degradation of the edaphic conditions of habitats occurs here. Under such conditions, the development of undergrowth of coniferous (forest-forming) species is extremely limited, and formation of forest coenoses will require many decades. On the burnt sites of light coniferous forests in the southwestern parts of Transbaikalia, with partial preservation of individual trees of forest-forming species, the initial stage of formation of a canopy of small-leaved tree species, sometimes with the participation of conifers, has been noted, which indicates satisfactory conditions for primary taiga formation in a rather short time period. Activities on artificial and combined forest restoration in all the considered areas of Western Transbaikalia will contribute to a more rapid restoration of forests if new fires are excluded.

The article considers the ethnocontact zones (ECZ) of Buryatia, by which the authors understand a type of ethnocultural regions and chorological objects consisting of intersecting, overlapping or adjacent ethnic areas and ethnic boundaries. Buryatia is presented as a key region - a republic with a mosaic, diverse and tolerant population, which is a multicultural complexly organized ethnocultural region, a system of ethnocontact zones of different hierarchical levels. At the same time, Buryatia is a part of a larger ethnocontact zone. Statistical, cartographic, expeditionary, sociological and other methods were used. The municipalities of Buryatia were grouped by ethnic composition and ethnic mosaic index, and calculations were carried out for nine key ECZ of rural settlements. An attempt was made to identify the specifics of the territorial structure of the ethnocontact zone, its place in the classification, historical and geographical features and factors of formation and transformation of the ECZ at different historical and geographical stages. The main factors identified are positional (including the border position), landscape, political and administrative factors, the nature of interethnic and intercivilizational interaction, models of territory development and forms of interethnic interaction. Schematic maps characterizing the ECZ of municipalities were made. The study of ethnocontact zones also has practical significance in addition to scientific one. It can be used by governing bodies to implement regional policies at different levels. The materials can also be used in the educational process and activities and in planning tourism development.

The territory of the Far Eastern Federal District has a variety of natural and climatic conditions that affect the consumption of certain types of food. It is noted that the regions of the district are characterized by a high share of costs (up to 35 %) for the purchase of food. The article considers the structure of consumption of basic foodstuffs in the regions of the Far Eastern Federal District in 2016 and 2021. Based on the analysis of the share of consumption of basic foodstuffs from the standard ones, the regions have been classified by type of consumption: regions with rational nutrition, regions with relatively rational nutrition, regions with poorly rational nutrition, and regions with an irrational type of nutrition. It has been revealed that there are no regions with rational nutrition in the Far Eastern Federal District. The analysis showed that in 2016, more than half of the regions of the Far Eastern Federal District belonged to type 1 (regions with relatively rational nutrition), namely: the Republic of Buryatia, Primorsky, Khabarovsk, Kamchatka and Zabaykalsky krais, and Amur and Sakhalin oblasts; type 2 (regions with poorly rational nutrition) included the Republic of Sakha (Yakutia), and Magadan and Jewish autonomous oblasts, and type 3 (regions with irrational nutrition) - Chukotka autonomous okrug. It has been established that in 2021, the number of regions with relatively rational nutrition of the population (type 1) decreased compared to 2016, the Republic of Buryatia and Sakhalin oblast left their number, while Jewish autonomous oblast moved to type 1. Chukotka autonomous okrug remained in type 3. It has been determined that the growth of per capita income in the regions does not lead to a reduction in the share of food costs, but contributes to an increase in the consumption of protein products while reducing the intake of potatoes, bread products and vegetables. It has been revealed that one of the reasons for the low consumption of certain food products is a reduction in own production of agricultural products in the subjects of the Far Eastern Federal District. The need to implement a policy of self-sufficiency in agricultural products that can be produced in the regions of the district, taking into account agroclimatic conditions, has been noted.

The ecosystem approach to assessing the object of accumulated environmental damage (AED) has been implemented; it consists in the possibility of using bioassay methods together with chemical-analytical methods for the environmental assessment of soils and bottom sediments of the closed authorized landfill located in the Gulf of Finland basin. It has been revealed that the cause of pollution of the basin territory is the long-term storage of mixed landfill masses without observing environmental protection technologies. It has been established that the current regulatory and methodological framework does not provide for reliable accounting of the factors of influence of AED objects, which leads to distortions of the parameters of eco-safety of territories and assessments of the impact on the surrounding geosystems. New pollutants with high toxicity can be formed at the objects of accumulated environmental damage. Their presence cannot be predicted only on the basis of chemical analysis. In this regard, the environmental control system should involve integral methods for assessing the toxicity of natural environments, which include bioassay. Bioassay, which performs the function of tactical control, allows us to approach the assessment of the impact of AED objects on the ecosystem and to quickly establish the danger of the object for the environment. In this work, ecotoxicological studies of soils and bottom soils by bioassay methods were carried out using a set of biotest systems including representatives of different trophic levels (crustaceans, infusoria, algae, and seeds of higher plants). The study used eluate and contact bioassay methods, which enabled to determine the most sensitive biotests. The obtained research results make it possible to properly justify scientific and applied solutions for the restoration of the cumulative technogenic background of natural and economic systems located in the Gulf of Finland basin.

The article presents information on disturbed lands in oil production areas in Western Siberia and Nenets Autonomous Okrug. The technogenic disturbances of the surface that occur during exploration and production of hydrocarbon raw materials were examined. The stages of restoration of the vegetation cover at geological exploration sites and in Nenets Autonomous Okrug were revealed. The analysis of primary successions of vegetation that arise after complete destruction of the soil and vegetation cover is given. It has been revealed that willow communities are formed at the studied geological exploration sites by plant succession. It has been established that in Western Siberia over a 25-year period, plant communities have been formed on bulk drilling sites that rise above the areas of disturbed swamps by 1-4 m that differ significantly from the vegetation of swamps. It has been concluded that the process of restoration of plant communities occurs by the way of formation of forest ecosystems; woody plants such as birches, pines, willows settle along with herbaceous plants. This is facilitated by the creation of favorable conditions for the growth of trees and shrubs in local areas due to embankments, an increase in the thickness of the root layer, and an improvement of the hydrothermal regime. Practical measures are proposed for the restoration of disturbed lands and the reduction of their negative impact on the environment. Various grass mixtures have been tested during restoration work. Promising plant species for sodding disturbed tundra areas in the Nenets Autonomous Okrug territory have been identified. The expediency of using wild species seeds, more resistant to local conditions, for sowing along with cultivated plants has been established. It is proposed to involve the indigenous population migrating across the tundra with herds of reindeer in collecting wild plant seeds and sowing plants in disturbed areas. For the first time, the feasibility of using small-sized (garden) equipment transported by helicopter for the restoration of hard-to-reach disturbed areas has been tested and proven. Technologies for the restoration of disturbed lands adapted to the conditions of the North are proposed.

The article presents information on the finds of shells of mollusks of the genera Monodacna, Unio, Lanceolaria, Planorbis, and Amuropaludina in the Pleistocene and Holocene deposits in Transbaikalia. Their shells are morphologically similar to those of modern species inhabiting regions of Russia that are geographically remote from Transbaikalia. Their ranges in the past were much more extensive than at present. The history of the existence and extinction of the species under discussion in Transbaikalia is reconstructed based on fossil finds and modern collections of mollusks. The ranges of the European species of the genera Monodacna, Unio, Planorbis, and the Far Eastern species of the genera Lanceolaria and Amuropaludina changed during the time period from the Pleistocene to the Holocene under the influence of climatic factors during the Ice Age. When comparing the absolute age of fossil shell finds or their host sediments with periods of warming and cooling on the regional geochronological scale, geochronological markers of the existence and extinction of the species under discussion in Transbaikalia were revealed. Thermophilic European species, widespread in the Pleistocene, became extinct in Eastern Siberia and Transbaikalia during the Ice Age, their ranges were interrupted and limited to the main part in Europe. The same scenario developed for the Far Eastern stenothermic species, which became extinct in Transbaikalia during the cold period of the Holocene. About 2-1,5 thousand years ago, their range, covering the entire Amur basin, was interrupted and limited to the main part in the Far East. The fact of habitation of local populations of European species of the common and wedge-shaped pearl mussel (Unio pictorum and U. tumidus) and the Far Eastern species of the Kian amuranodont (Amuranodonta kijaensis) in the refugium lakes of Transbaikalia has been noted. Changes associated with the natural cycles of cooling and warming in the Pleistocene and Holocene can be considered as a manifestation of climatogenic succession, during which the extinction of stenothermic species at the regional level and the rupture of ranges at the global level occurred.

The use of natural environmentally friendly resources in engineering systems, in particular, solar energy technologies, helps to cut energy costs, thereby reducing production costs and anthropogenic load on the environment. Long-term hydrometeorological data were studied and processed using mathematical statistics methods, the reliability of the interaction was determined, and regression equations were obtained to predict the natural and climatic conditions along the coast of the Kara-Bogaz-Gol Gulf in the Caspian Sea. Natural solar energy resource potentials of the gulf coast were considered. Using innovative techniques, the task is to assess the thermal resource potentials of solar radiation; consider the salt deposits of the gulf as heat accumulators for the development, implementation and application of solar thermal energy technologies; and justify the technical and economic feasibility of their use in engineering systems in the gulf. For development, creation and implementation of solar thermal and electric power stations in the study area applying innovative methods with consideration of natural and climatic conditions and atmospheric phenomena, gross, technical, economic and environmental capabilities of the region were assessed. The solar energy potentials of photoconverter and heat collector at the optimum tilt angle were estimated based on theoretical studies and methodological calculations, taking into account duration of sunshine; hour angle to inclined and normally oriented surface; movement of solar declination to an inclined surface and to the horizon; scattering of radiation, albedo, angular parameters of arrival and solar radiation; average monthly and annual temperature of outdoor air and operation of a solar installation; specific energy parameters of a solar installation, etc. The obtained scientifically substantiated and systematized results can be used in the development of design and estimate documentation, preparation of feasibility studies for the creation of various solar technology complexes in the Caspian region, which will contribute to strengthening of energy security, sustainable development of energy systems when using autonomous technological units based on solar energy, growth of production of natural chemical elements, reduction of energy consumption of organic fuel, and improvement of the environmental situation in the region of the Kara-Bogaz-Gol Gulf.

The article considers the main areas for development of mountain tourism in Kyrgyzstan based on a comprehensive study of the tourism potential. An integrated research of the country’s natural and recreational resources associated with altitudinal zonality has been conducted. They include mountains, glaciers, mineral waters, therapeutic muds, lake beaches, etc. Taking into account global trends in the development of the tourism market, three promising areas of mountain tourism in Kyrgyzstan have been identified, namely: resort and recreational, travel along the Great Silk Road, and mountain-adventure, the key role in the development of which is assigned to mountaineering. It is shown that the tourism and recreational potential of the republic is mainly associated with high-mountain territories. It is concluded that in order to unlock this potential, it is necessary to create an international mountaineering center, develop tourism infrastructure and modernize the existing one, as well as to enhance control in the field of environmental protection. Significant investments are required to achieve these goals; some of them can be attracted through foreign investors. The implementation of these measures should contribute to the sustainable development of the republic and improve the quality of life of the population.