Home – Home – Jornals – Journal of Applied Mechanics and Technical Physics 2020 number 5

We have studied volcanogenic diamonds in the context of a discussion of their genesis, including some assumption on their artificial origin. The carbon isotope composition of diamonds collected from the eruption products of Tolbachik Volcano (δ¹³C_VPDB from -22 to -29 ‰) is within the range of the δ¹³C_VPDB values of natural diamonds, including those from kimberlites. The ¹⁵N_Air values of the Tolbachik diamonds, measured for the first time (-2.58 and -2.32 ‰), correspond to δ¹⁵N_Air of volcanic gases and differ from that of atmospheric nitrogen (δ¹⁵N_Air = 0 ‰), which may be expected in synthetic diamonds. In the studied volcanogenic diamonds, as in synthetic ones, the nitrogen impurity is unaggregated. However, such an unaggregated form of nitrogen is specific to many natural diamonds (e.g., variety II diamonds, according to Orlov’s classification). Impurity elements (Cl, F, O, S, Si, Al, Ca, and Na) are locally concentrated in volcanogenic diamonds; they are a constituent of micro- and nanoinclusions in them. The high contents of F and Cl in the studied diamonds are correlated with the composition of volcanic gases; there is no reason to expect a similar correlation in synthetic diamonds. Moreover, the studied cube-octahedral Tolbachik diamonds have a number of accessory forms, some of which are not observed in synthetic diamonds. Their surfaces are frequently covered with films composed of Mg-Fe and Ca-Mg silicates, aluminosilicates, sulfates, metal alloys, and native Al. Mineral inclusions in the studied diamonds are Mn-Ni-Si alloys and silicides varying in composition from (Mn,Ni)₄Si to (Mn,Ni)₅Si₂, Mn5Si2, and pure Mn silicide MnSi. Summing up the obtained data, we conclude that volcanogenic diamonds form in a strongly reducing environment, in which silicides and native metals and their alloys are stable. The predominant cube-octahedral morphology of these diamonds and the unaggregated nitrogen impurity point to their short-term residence under high-temperature conditions. This makes them similar, to some extent, to synthetic diamonds. There are, however, clear differences as well. Volcanogenic diamonds are similar in compositional peculiarities, including isotope compositions, to natural diamonds that form under most unfavorable conditions, such as cuboids, balases, carbonado, and some diamonds of the eclogite paragenesis. They also resemble diamonds found in situ in harzburgite and chromitite of ophiolites. This suggests a specific mechanism of formation of both volcanogenic and ophiolitic diamonds in the oceanic lithosphere.

The paper discusses the mechanisms of formation of high-purity quartzites from the Bural-Sardyk deposit. Based on a stadial analysis of the sedimentary-metamorphic sequence, we interpret the succession of postsedimentary transformations of high-silica rocks. Comprehensive studies using geological and geochemical methods and isotope research data reveal the role of tectonics, magmatism, metamorphism (regional and contact), and dynamic metamorphism in the formation of high-purity quartzites. Two main varieties of tectonites have been identified and described: stress-metamorphic tectonites and cataclasites. The paper presents a new geological map of the Bural-Sardyk deposit on a 1:10,000 scale.

We present results of geochemical and Sr-Nd isotope studies of rocks and of local dating and determination of the Lu-Hf isotope composition of zircons from late Vendian-early Cambrian and Cambrian-Ordovician intrusive associations (granitoids and gabbroids) of the Kaa-Khem and East Tannu-Ola batholiths in Eastern Tuva. The wide ranges of the ε_Nd values (6.9 to 0.5) of rocks and the ε_Hf values of magmatic and inherited zircons reflect the diversity of the magma sources of late Vendian-early Paleozoic intrusive associations formed at the island arc and accretion-collision stages. Late Vendian (572-562 Ma, Kopto and Buren massifs) and early Cambrian (522-518 Ma, East Tannu-Ola batholith) island arc tholeiitic and calc-alkalic plagiogranitoids resulted from the melting of the Vendian-early Cambrian island arc crust without the contribution of a more ancient crustal material. The subalkalic gabbro-monzodiorite-granosyenite association of the Zubovka massif (510 Ma) formed from a mantle source depleted isotopically but enriched in incompatible elements, with the participation of an island arc crust material; this process took place in the early phase of plume activity at the accretion-collision stage. Island arc complexes were the main source of Cambrian-Ordovician accretion-collision calc-alkalic plagiogranitoids (500-450 Ma, Terektyg-Cheder, Karaos, Tapsa, Baisyut, and other massifs). Variations in their composition were due to the melting of thick crust, whose isotopic heterogeneity was caused by the different contributions of a more ancient crustal source. The crust of the Tuva-Mongolian terrane made the main contribution to the formation of the potassic granitoids of the Bren’ massif (450 Ma), marking the completion of accretion-collision processes in this region. The isotope parameters of the Vendian-early Paleozoic granitoids are indicators of the crust formation and evolution in the course of subduction and accretion-collision processes.

The evolution of the eastern part of the Mongol-Okhotsk Orogenic Belt marks the late Mesozoic accretion-collision processes involving the Siberian and Sino-Korean plates. Tectonic restructuring in the region was accompanied by the formation of igneous complexes, which replaced each other almost without a temporal break. Andesitic magmatism was widely manifested in the southern framing of the eastern part of the belt. Its study is complicated by the isolation of volcanic fields and their confinement to the Amur-Zeya depression. Study of the geochemical and geochronological characteristics of igneous complexes there made it possible to recognize and systematize the temporal stages and substantiate the geodynamic formation of these rocks. However, there are controversial geologic objects, such as the Isikan volcanic field. We present the first data on the isotopic age and chemical and isotope-chemical compositions of the rocks of this field. ⁴⁰Ar/³⁹Ar dating showed that the integrated age of the dacitic matrix is 113.0 ± 2.6 Ma and the plateau age is ??121.0 ± 1.6 Ma. In chemical composition the studied volcanic rocks are similar to rocks of the Poyarkov volcanic complex developed within the Bureya-Jiamusi superterrane, which formed under subduction in the period 120-105 Ma. In geochemical and isotope-geochemical characteristics the volcanics are similar to rocks of igneous belts of Andean-type active continental margins.

A high-amplitude negative δ¹³С anomaly (-11 ‰ V-PDB) has been found in the carbonate horizons of the Chistyakovka Formation of the Taseeva Group in the type sections of the southern Yenisei Ridge. The δ¹⁸О values (-2.7 to -5.4 ‰ V-PDB) and the lithologic features of carbonates indicate that these are primary sedimentary rocks and their isotope parameters reflect the primary isotope composition of the paleobasin waters. The negative δ¹³С excursion in the Chistyakovka Formation is close in stratigraphic position and amplitude to similar isotope excursion in the Vendian strata of the southern Siberian Platform and to the global middle Ediacaran Shuram-Wonoka anomaly. According to the data on clastic zircons, the age of the Chistyakovka Formation is no older than 580 Ma, which agrees with the earlier estimated age of the Shuram-Wonoka event. As follows from the data obtained, the age of the basement of the Taseeva Group is no older than 600 Ma. This provides a more accurate correlation of the Vendian complex along the southwestern margin of the Siberian Platform. The different stratigraphic scales of the sediments indicate that the marginal trough here began to form at different times (from late Riphean to late Vendian), which explains its segmented structure.

Deep and ultradeep oil and gas have been the prominent direction of international exploration in recent years. The deep oil and gas resources are distributed predominantly in three domains of carbonate, clastic, and igneous rocks. The carbonate rock reservoirs contain about 40 % of global oil and gas reserves owing to their superior reservoir properties. In recent years, a number of large oil and gas fields have been discovered in deep marine carbonate rocks in China, especially in the Sichuan and Tarim basins, which shows a vast oil and gas exploration potential in these rocks. In this paper, the genesis and source of deep natural gas in the Tarim and Sichuan basins have been systematically studied. The results show that the natural gas in deep marine carbonate rock reservoirs is generated not only from the later deep-source rocks. The substantial cracking of crude oil and pyrobitumen in the reservoir under conditions of great burial depth and high geotemperature can also provide abundant natural gas sources for deep reservoir. Accordingly, the contribution of gas from oil cracking should be considered in the evaluation of deep natural gas resources.

The bottom sediments of lakes with different mineralization located in the basins of inland areas are high-resolution archives of climate and environmental changes. We present results of study of the Late Pleistocene-Holocene sediments of freshwater Lake Baunt, one of the lakes of the Baunt (Tsipa) depression in the permafrost zone in northern Buryatia. The sediments were studied by XRD, IR spectroscopy, laser granulometry, elemental analysis, AMS dating, etc. Mineral analysis of the bottom sediments with an age of ~18 ka has revealed predominant phyllosilicates, quartz, and feldspars. Mathematical modeling of complex XRD spectra made it possible to identify chlorite, muscovite, illite, mixed-layer illite-smectite and chlorite-smectite, and kaolinite among the phyllosilicates. We have determined their structural and crystal-chemical features and quantitative proportions in the section (800 cm long core), which vary in accordance with the climate cycles and lake level fluctuations. The results obtained helped to reconstruct the evolution of the Lake Baunt basin controlled by the regional climate throughout the Late Pleistocene-Holocene. This paper continues a series of our publications concerned with the reconstruction of the Late Pleistocene-Holocene climate in East Siberia by comprehensive studies of the mineral composition of sedimentary sections of small lakes.

Structural and geological research has shown that the extension of the Russian Plate caused a neotectonic transition of the deformed material from the Voronezh and Volga-Kama anteclises to neighboring syneclises, primarily the deepest Peri-Caspian. The resulting geologic structures and landforms morphologically resembled landslides, but their large (up to many hundreds of kilometers) lateral sizes excluded the influence of exogenous processes and made it necessary to treat this event as a gravitational collapse involving a significant crustal mass. This phenomenon was previously considered for orogens only, but the conditions for its appearance here existed too: In the late Cenozoic, the East European Platform experienced a collisional pressure from the southern boundary of the Eurasian Plate, which led to a gravitationally unstable uplift. The collapse was best manifested in the zones of junction of anteclises and syneclises, where lenses of the thickened continental crust are thinned beneath anteclises. This fact, along with the published modeling data, gave grounds to state that the platform collapse was favored by the lenticular crustal structure: The light crustal lenses forming anteclises floated up under compression and diverged under subsequent decompression. Gravitational extension and subsidence in the anteclise apexes was compensated by compression near the syneclises, where folded dislocations and neotectonic ramparts formed. It has been established that a gravitational collapse results in a specific paragenesis of platform structures and morphostructures, which can help to identify its manifestations in other places and to make an unbiased assessment of the relationship between the relief formation and tectonics. In general, the data obtained suggest a relationship between the recent activity of passive continental margins and the gravitational collapse of the largest lenses of the continental crust.

The paper considers the basic regularities of inductively induced polarization (IIP) manifestation in the transient electromagnetic method. When calculating inductive transient responses of a polarizable ground, we assumed that the electrical conductivity of geologic materials is described by the Cole-Cole model. To present and analyze the results of computer-based simulation of the IIP phenomenon, we used a normalized transient response. It is defined as the ratio of the transient electromotive force (EMF) response of a polarizable ground to the EMF response of a ground that differs from the polarizable one only in that it has zero chargeability. The coordinates of the minimum of the normalized transient response are useful for an overall assessment of IIP manifestation. We show, by the example of a homogeneous polarizable half-space, how the inductive transient response is affected by the Cole-Cole model parameters and the size of transmitter and receiver loops. For a two-layer ground, IIP manifestation depends also on whether the base or upper layer is polarizable, as well as on the layer thickness. Inductively induced polarization is most pronounced when a conductive polarizable layer overlies a resistive nonpolarizable base. In this case, at a certain thickness of the layer, the IIP effect far exceeds that observed in the presence of a thick polarizable layer and even of a homogeneous polarizable half-space.

Marine geoelectromagnetic sounding with artificial sources is strongly hindered by the influence of a conductive seawater layer. There is only one known wide successful application of electrical prospecting in this field - Controlled Source Electromagnetic Method (CSEM). However, this method has unfortunate limitations: the need to submerge an electromagnetic probe to the bottom of a deep (more than 1000 m) sea and the great rafting (~15 km). The method is not applicable in an ice-covered sea. Deep sounding from the sea surface and, hence, from the ice surface is possible if the TM polarization field is used. This field is generated by a vertical electric line (VEL) or a circular electric dipole (CED). The former has drawbacks even when it is used at sea. At the same time, a CED is efficient in one-dimensional and three-dimensional media in frequency and time modes. We have developed a three-dimensional mathematical tool for the CED field in the Born approximation, which is quite adequate in a conductive section with deep local inhomogeneities. The research is carried out within the framework of a geophysical project using the Arctic drift ices.

Stability of a subsonic boundary layer with heat supply into its narrow band is studied. The maximum length of the stable boundary layer in the case of heat supply is found to be approximately three times smaller as compared to the case of a thermally insulated wall without heat supply. The frequency range of disturbances and their growth rates are approximately doubled. In contrast to the case without heat supply, three-dimensional disturbances are the most rapidly growing disturbances. In the case of a heated wall, the growth rate of disturbances decreases after heat supply into the boundary layer, which may lead to an increase in the length of the laminar region of the boundary layer.

Results of experimental and numerical modeling of a supersonic flow around a cylinder with a frontal gas-permeable high-porosity insert aligned at different angles of attack are presented. The experiments are performed in a supersonic wind tunnel at the Mach number M¥ =7 and unit Reynolds number Re1=1.5 х 106 m-1 in the range of the angles of attack 0-25oC. The numerical simulations are performed by means of solving three-dimensional Reynolds-averaged Navier-Stokes equations with the use of a three-dimensional annular skeleton model of the porous material. The drag and lift coefficients for a cylinder with a 95% porosity and pore diameter of 2 mm are obtained for different values of the insert length and angle of attack.

Flight experiments aimed at studying the transition from the laminar to turbulent flow in the boundary layer on the glider wing at different levels of atmospheric turbulence performed in the 1980s are reviewed. The results are obtained by means of hot-wire measurements and visualization of the flow on the wing surface by the method of sublimating coatings. The transition is found to proceed in several stages: emergence, evolution, and failure of a discrete packet of instability waves in the region of the adverse pressure gradient. The data obtained in the study are compared with the results of similar investigations carried out in a large wind tunnel on the same real glider wing at realistic Reynolds numbers.

This paper describes a study of a laminar separated flow in a compression angle for the Mach number of the incident flow M = 6; 8. The shock-wave structure of the flow in an attachment region is considered. The formation mechanism of a high-pressure layer, which is a narrow gas region located above the boundary layer downstream from the attachment line, is investigated.

The interaction of a laminar boundary layer with a shock wave at a Mach number M = 1.43 is studied by numerical simulation. The results obtained by direct numerical simulation are compared with the results of calculations using the Reynolds-averaged Navier-Stokes (RANS) equations supplemented with different turbulence models describing laminar-turbulent transition. The possibility of determining the position of the flow turbulence zone based on linear stability theory and the eN-method is estimated. Comparison of the numerical simulation with experimental data shows that the engineering RANS methods can be used to study supersonic flows in which transition to turbulence occurs in regions of interaction of the shock wave with the boundary layer.

This paper presents a brief overview of the most significant studies on magneto-plasma aerodynamics performed at the Khristianovich Institute of Theoretical and Applied Mechanics Siberian Branch, Russian Academy of Sciences in the last 20 years.

This paper describes a study of curvature of gas trajectory at the initial section of a supersonic nonisobaric jet on the features of unsteady perturbations from the Kelvin-Helmholtz instability class. It is shown that, in the presence of a barrel-shaped structure, steady Taylor-Gortler perturbations in the form of longitudinal structures (banded formations) arise. Studies for a mixing layer with a Mach number M=1.5 are carried out. The possibility of amplifying and suppressing the growth of Kelvin-Helmholtz perturbations by steady Taylor-Gortler waves. A nonlinear problem is solved within the framework of three-wave resonance interactions in a local-parallel approximation. A pumping wave is a steady Taylor-Gortler wave. It is shown that, at the initial section, small-amplitude traveling waves can be both amplified and suppressed.

A PIV method is used to measure the flow velocity in a zone of interaction between a shock wave and a boundary layer on a plate in the case where the Mach number is M=1.43. Two states of the incident boundary layer are considered (laminar and turbulent), and a boundary layer thickness can be two orders of magnitude smaller than the characteristic longitudinal scale of the flow. The results of measuring the velocity in the boundary layer, obtained using the PIV method at different settings of the equipment, and the results of measurements performed using various algorithms for determining the tracer particle displacement and reconstructing velocity fields from them. It is shown that the main constraint for increasing the spatial resolution is the tracer particle inertia.

This paper presents an experimental study of diffusion jet combustion of gas at different flow rates of CH4-N2 and a constant flow rate of coal. Entrainment curves for a diffusion flame for different nozzle diameters are obtained. It is shown that an increase in the nozzle diameter causes a decrease in the minimum residual flow rate of the fuel gas at which stable combustion is possible. As coal is supplied, the residual flow rate of the fuel gas also becomes slightly lower. The fluorescent glow of OH, which makes it possible to analyze the position and dynamics of the flame front is recorded.

Structural changes in a supersonic flow in a variable-section channels with axial injection of kerosene induced by the action of a jet generating a throttling effect are numerically simulated. Reynolds-averaged Navier-Stokes equations closed by the k-e turbulence model are solved. Kerosene combustion if modeled by equations of simplified chemical kinetics. The evolution of the processes in the channel is analyzed numerically and analytically for different types of the fuel (hydrogen, ethylene, and kerosene), and comparisons with experimental data are performed. It is found that high-intensity gas-dynamic pulses have to be used to form a transonic region in the case where kerosene is used as a fuel.

A hybrid model (combining the molecular dynamics and Monte Carlo methods) for computing the gas flow in a cylindrical channel with allowance for heat exchange between the gas molecules with the surface and adsorption of molecules on the channel surface is developed and improved. Two variants of the channel flow are considered: the flow in which the total number of molecules in the system remains unchanged in time and the flow with simulation of an infinite volume of vessels or a vessel with a constant pressure. Three variants of molecule interaction with the wall are analyzed: 1) the molecule experiences elastic scattering with a probability WE; 2) inelastic scattering (scattering with energy exchange) occurs with a probability WT; 3) deposition (adsorption) of the molecule onto the solid surface occurs with a probability WA. The sum of the probabilities if equal to unity. It is found that the allowance for adsorption exerts a significant effect on the velocity of the center of mass of molecules and on the density of the flux of molecules in computational volumes.

A technology of growing the bone tissue on a thin scaffold in a rotational bioreactor is developed. An optimal regime of cell bulk cultivation is determined for testing the method, and an optical method for diagnostics of the bone tissue evolution in the course of its growing is developed. The fluid flow in the bioreactor is numerically simulated, which allows significant simplification of the medical experiment and appropriate choice of the optimal values of the rotation frequencies and shear stresses acting on the cell material located on the scaffold. The optical diagnostics of the scaffold samples in the course of dynamic cultivation in the bioreactor is performed by the method of laser-induced fluorescence. An algorithm based on the principal component method is applied to analyze the spectral data; as a result, the spectra of excitation and fluorescent emission of the basic fluorescent substances in the sample (tyrosine and tryptophase aminoacids, structural protein (collagene), and fluorescent structures of polycaprolactone) are calculated. It is found that the contribution of the component corresponding to collagene increases in the course of dynamic cultivation in the samples, which testifies to effective formation of the extracellular matrix of the bone.

This paper presents the results of a numerical study of the effect of a positive longitudinal pressure gradient in a sudden pipe expansion on the turbulent two-phase flow structure and local heat transfer. It is shown that the longitudinal pressure gradient has a significant effect on flow characteristics and heat transfer in a separated gas-droplet flow. Increasing the opening angle of the diffuser leads to a significant increase in the degree flow turbulence (almost twofold increase compared to gas-droplet flow in pipe with a sudden expansion at φ = 0 ^oC). It is found that in the flow under study, the length of the recirculation zone increases in comparison with separation gas-droplet flow at φ = 0 ^oC and the point of maximum heat transfer rate shifts downstream. In this case, the coordinate of the point of maximum heat transfer rate does not coincide with the coordinate of the reattachment point of the detached two-phase flow.

This paper presents a brief overview of experimental studies performed at the Institute of Thermophysics SB RAS to model jets of low-thrust liquid rocket engines used as control and orientation thrusters of spacecrafts, including the International Space Station. Modeling criteria are formulated for the parameters of both the gas flow and the near-wall film of the liquid used for nozzle cooling. The experimental setup, diagnostic methods, and experimental results on the interaction of the near-wall liquid film with co-current gas flow inside the supersonic nozzle and during jet expansion into vacuum are described. The problem of minimizing backflows leading to contamination of the spacecraft external surfaces is discussed.

This paper describes the results of experimental studies of a flow using the prototype of a propeller-type microhydraulic turbine. The tests are carried out on a testbed in which atmospheric air is used as a working medium. The measurements carried out with the help of a two-component laser-Doppler anemometer are used to obtain velocity distributions behind an impeller in the case where the operating modes of the device change in a wide range. It is shown that the created model microhydraulic turbine has optimal parameters for the conditions set during the design, and a change in the operating mode of the device from nominal parameters to underload or overload increases the residual swirl of the flow and the generation of strong hydrodynamic instability in the form of a precessing vortex bundle. In this case, axial velocity over the cross section is distributed unevenly and the flow pulsation level is increased.

The aerodynamics of a laboratory model of an improved furnace with a four-vortex coal combustion scheme is studied using laser Doppler anemometry. For the isothermal case, the distributions of the averaged velocity and velocity pulsations are obtained for various flow regimes. The main features of the flow are established. Comparison of the experimental results with previous PIV measurements shows that they are in good agreement.

A method of gas-phase deposition of diamond structures with the use of a high-velocity jets for transporting gases activated in a microwave plasma to the substrate is developed. The diamond structures are synthesized from a hydrogen-methane mixture with the methane concentration of 1%. The influence of the gas mixture flow rate on the synthesis of the diamond structures with an unchanged composition of the mixture, pressure in the deposition chamber, and substrate temperature is studied. It is found that an increase in the flow rate leads to an increase in the polycrystalline film density and in the size of the diamond crystals forming the film. The composition of the mixture at the discharge chamber exit is numerically analyzed for different flow rates of the gas mixture. A correlation of the mixture composition with the growth rate and quality of the diamond structures is demonstrated.

Problems arising in the analysis of the physical and mechanical properties of composite materials on polymer matrices are under study. The structural features of such materials and the resulting difficulties in the development and implementation of corresponding models are discussed. A technique for determining the effective strain-strength, thermophysical, and electrophysical properties of the compositions is proposed, and a number of examples are considered. Particular attention is paid to solving computer design problems in order to determine the composition and structure of composites under specified constraints on their effective properties. Initial data for solving these problems are obtained both in field and computational experiments. Directions for further research are identified.

A review of works devoted to the study of the mechanical properties, stability, and buckling of graphene and carbon nanotubes is presented. Most of these results are obtained by means of molecular dynamics and molecular mechanics, which make it possible to effectively investigate the mechanical properties and stability of nanostructures. The data on the strength of graphene are presented, and bending modes for armchair and zigzag graphene sheets are analyzed. The stability and bending modes of natural vibrations of zigzag' and armchair nanotubes are analyzed.

A series of computations based on experimental data on the depth of projectile penetration into targets is performed for verification of parameters of ballistic stability of plates made of Al2O3, B4C, and SiC ceramics. Interaction of a heart-shaped steel projectile and a target made of an aluminum alloy with a variable-thickness ceramic plate positioned ahead of the target is simulated. The computed results are compared with experimental data for various ceramic targets 1-5 mm thick and projectile velocities of 810-850m/s.

A series of numerical simulations of the impact parameters of projectiles of different shapes with massive targets is performed. It is experimentally demonstrated that the dependences of the dimensionless depths of the craters formed by projectiles of different shapes on the dimensionless kinetic energy is described by a single curve of the modeling process.

This paper considers an energy approach to assessing the state of a cerebral aneurysm as a hydroelastic system consisting of an elastic vessel wall and oncoming blood flow. Assuming that the elastic energy of a vessel with an aneurysm in combination with the bending energy and kinetic energy is spent only on viscous flow dissipation in the structure, we performed a series of numerical calculations for model configurations of a fusiform aneurysm in the absence and in the presence of a diverticulum of different sizes relative to the size of the aneurysm body. It is shown that pressure-velocity diagrams are in good agreement with clinical data. Using numerical simulation, it is shown that a diverticulum of small size has a significant effect on hemodynamics inside the body of the aneurysm, and at a large diverticulum size, the vortex induced inside the diverticulum is almost completely localized in it.

Results of an experimental study of the microstructure and microhardness of a functionally graded material based on 316L stainless steel and ceramic particles of tungsten carbide (WC) created by the method of additive laser fusion are reported. Defect-free high-quality metal-ceramic coatings with different fractions of ceramics are obtained. It is demonstrate by the methods of optical and scanning electron microscopy and energy dispersion analysis that the laser action leads to dissolution of WC particles. The composition of the resultant coating, which has a dendrite character, includes iron and chromium carbides. The range of the coating microhardness is found to be HV_0.3 = 280-430.

The formation of single-layer and multilayer grapheme by chemical vapor deposition has been studied experimentally. The structure of the coatings formed at different temperatures and compositions of the gas mixture have been analyzed. Modes for transferring graphene structures to various substrates have been developed. Transparent flexible conductive polyethylene terephthalate-ethylene vinyl acetate-graphene and polymethylmethacrylate-graphene compositeshave been obtained.

In studies of tree fire damages, attention is usually paid to growth and development of wood (xylem). But for tree vitality a very important role belongs to the tissues outside the cambium - phloem (inner bark). The object of this work was to continue the study of anatomical features and chemical composition of inner bark of Scots pine Рinus sylvestris L. stems with different fire scars after prescribed fires of different intensity. The fire experiments were carried out in pine stands in Lower Angara river region of the Angara provenance, Krasnoyarsk Krai, Central Siberia. Anatomic analyses of stem cores of experimental and control trees were carried out by the methods of light microscopy and histochemistry. It was shown that eight years after the low-intensity and 13 years after the medium- and high-intensity fires, the thickness of inner bark increased in all the studied trees, as well as in the control. Moreover, a decrease in the number of annual phloem layers between the cambium and periderm was noted. The number of cells in the radial row of the conducting phloem after a low-intensity fire was almost the same in inner bark of trees damaged by fire and not damaged (control), after a medium-intensity fire, it decreased with an increase of fire scars square, after a high-intensity fire a tendency to increase in trees with severe fire damage was noted. The content of axial parenchyma was found to increase with increase of stem fire damage in trees after a low-intensity fire and decreased after fires of medium and high intensity. There was a tendency to an increase in the frequency of phloem rays in tree trunks with an increase of stem fire damage after a low-intensity fire; after medium-high and high-intensity fires any trends could not be identified. Distribution and amount of starch in the ray and axial parenchyma in the inner bark of all model trees was found to be almost the same. A tendency to increase the accumulation of callose in non-conductive phloem with an increase in the intensity of fire impact to the trunks was revealed. It is confirmed that the annual phloem layers formed after the fire do not contain lignin.

Carbon dioxide gas exchange and the pigment content of the photosynthetic apparatus of the Siberian stone pine Pinus sibirica Du Tour ecotypes vegetative scion from the West Siberian latitudinal transect grown on the geographical grafting plantation in the south of the Tomsk Region were studied. The latitudinal transect was represented by three ecotypes: Tomsk, the southern border of the range; Strezhevoy, middle taiga; Urengoy, northern border of the range. The age of the grafted trees was 20 years. It was shown that the photosynthesis intensity did not differ between ecotypes significantly, respiratory activity increased significantly from south to north, and the differences were 79 % between marginal ecotypes. The results of the experiment revealed that the respiration / photosynthesis ratio was twice as high in northern than in southern ecotype, which indicates a lower plant productivity of the northern ecotype. The results of measuring stomatal conductance and the intercellular CO₂ concentration showed that these values did not differ between ecotypes significantly. Research has revealed the tendency towards the decrease of green pigment contents in the middle taiga ecotype and the significant decrease those in the northern ecotype. The Chl a / b ratio increased from south to north from 2.7 to 3.2. On the contrary, the Chl/Car ratio decreased between marginal ecotypes from 6.2 to 5.7 due to the reduce of green pigment contents in the northern ecotype. The obtained data indicate the photosynthetic acclimation when ecotypes were moved to the warmer climate. The photosynthetic pigment synthesis and respiratory activity are largely regulated by hereditary factors (the ecotype origin).

The annual tree increment is one of the integral indicators of abiotic and biotic processes occurring in the forest ecosystem. The use of logistic regression models based on annual tree-ring growth data is a promising approach to studying tree mortality. The diversity of logistic variables in scientific research is a result of various choices of statistics (average, median, growth trend, etc.) and their score in the time-window for the past N (5, 10, ..., 40) years. We propose a new scheme for the formation of logistic variables that involves fixing the statistics for calculating the average and choosing two non-intersecting time-windows based on measurements of the annual tree-rings growth. The choice of non-overlapping «windows» enables setting the ratio of the average growth of annual rings of trees between the windows for different periods of time. We examined the past 41 years of tree growth. Logistic regression models are constructed on a set of pairs of non-intersecting «windows» with a limit on the values of the sensitivity and specification of at least 1.6. The calculation of the percentage prediction if a tree is living or dying was done based on the contingency table in the logistic regression model. The logistic regression models were visualized using ROC curves. The models were compared on an expert scale based on the calculated area under the ROC curves. The obtained logistic regression model was verified by the bootstrap method. The calculations were carried out for the Siberian stone pine Pinus sibirica du Tour growing in the Baikal region (the Khamar-Daban Ridge) using the R programming language. The computed logistic regression model helped us predict live and dead trees in more than 80 % of cases.

Of great importance when conducting forestry operations and scientific research is the accuracy of determining the height of trees. The height of trees in a particular area is usually calculated using models, where it is a function of diameter at breast height. Among simple models, three-parameter models are the most flexible and allow for more detailed transmission of the dependence. The purpose of the work is to select the most adequate one from the set of three-parameter models based on the materials used to measure model trees in birch stands, which conveys the relationship between the height of trees and diameter at breast height. On the materials of 23 sample plots with the measurement of model trees laid in birch stands of the Forest Experimental District of the Timiryazev Agricultural Academy, parameters were determined for 11 three-parameter models selected from literary sources. Model parameters were calculated by minimizing the standard error. The quality of the models was evaluated by the following metrics: the square root of the standard error, the coefficient of determination, the Akaike information criterion, the Bayes information criterion. The obtained results confirmed the advisability of using in practice the Mitcherlich equation (also known as Drakin-Vuyevsky, Chapman-Richards), which among the three-parameter models shows the best quality. The results of data analysis show that, from a statistical point of view, the differences obtained in the quality of models are not significant at the 5 % level ( t -test). Mitcherlich’s equation can be used in practice when carrying out forestry and research work in birch stands growing in the central regions of the European part of Russia. The methodology of the study allows you to repeat the same work for tree species and forest conditions, for which information about the nature of the relationship of height with the diameter at breast height is incomplete or absent.

The article presents the results of studies of ecological peculiarities of distribution of forest vegetation of the Ukrainian Rastochye based on an analysis of the floristic composition of plant communities. The following methods were used: phytoindication of ecological regimes based on ecological scales of F. N. Tsyganov, data mining methods, multidimensional ordination of plant communities based on the Principle Component Analysis, Analysis of Variance, statistical processing of ecological parameters of forest vegetation ecotopes. The results of a phytoindicative assessment of the conditions of forest phytocoenosis habitats are presented, which representing 22 associations of the classes Vaccinio-Piceetea, Oxycocco-Sphagnetea, Alnetea glutinosae and Querco-Fagetea, in nine parameters: Tm - thermal regime, Kn - continentality of climate, Om - climate humidity, Cr - cryo-climate, Hd - soil humidity, Tr - salt content, Rc - soil acidity, Nt - mineral nitrogen content, Lc - light-shading mode in plant community. The main regularity of the formation of ecotopes of forest vegetation of Ukrainian Rastochye consists in such a structure of interconnections between environmental parameters. The phytocenological space of the forest vegetation of Ukrainian Rastochye can be simplified in the form of an octagon, in the corners of which the associations are 8 located. Multidimensional ordination of forest vegetation of the Ukrainian Rastochye is characterized by the location of rare phytocenoses on the periphery of the ecological and phytocenological space. Practical significance. Patterns of the formation of forest vegetation allow solved the dynamics of vegetation cover, the relationships between different types of vegetation and environmental forecasting.

The paper considers the problem associated with the creation of databases. The review of available global, traditional soil databases is given. It is noted that they are of great scientific and practical importance. The description of the developed relational database «Heat Soil Portraits» in Microsoft Access is presented, based on the positive concept of representative soil profiles. The database contains information about the structural organization and thermal properties of natural and technogenic soils in Central Siberia. To create the database, we used materials from a morphological description, photographing, and ground radiometric survey in the thermal range of soil profiles obtained by the authors during the expeditionary work. Radiometric survey of soils was carried out according to the author’s method using a portable thermal camera. The structure of the designed database, its content and attributes are developed. Currently, the database includes information on 20 soil profiles of the main soil types and technogenic surface formations that are common in Central Siberia. The procedure for replenishing the created database with new information is simple to perform. A feature of the proposed database is the presence of photographs and thermal portraits attached to the description of a particular soil profile, which display the temperature distribution and structural organization of the soil profile. For each soil profile, temperature gradients are calculated that characterize the specific thermophysical properties of organogenic and mineral horizons. The prospect of DB development is replenishment with the results of radiometric surveys carried out in different seasons of the year and in different conditions of soil formation. Thus, the materials contained in the database can be used to assess the temporal and spatial variability of soils as a result of exposure to natural and anthropogenic factors.