Home – Home – Jornals – Combustion, Explosion and Shock Waves 2022 number 5

For the first time, exposures of ultramafic rocks of subvolcanic origin have been investigated at the foot of Mount Khanlauta (Kola Peninsula) located at a distance of ~2 km from the southwestern margin of the Pados-Tundra layered complex of dunite-harzburgite-orthopyroxenite composition, which hosts zones of chromitite and unconventional PGE mineralization. The ultramafic body is composed of micro- to fine-grained harzburgite and subordinate orthopyroxenite and has a cryptically zoned structure. The body is of E-W strike and has a small size with an apparent thickness of ~0.1 km; the exposed outcrops exhibit a blocky surface as a result of extensive cracking caused by degassing and rapid cooling of a parental komatiitic melt. Elements of columnar parting are recognized, which have a hexagonal shape in cross section and are consistent with the inferred subvolcanic origin. Two zones are identified. Zone I is formed by a more magnesian olivine with Mg# = 86.0-87.9 (0.15-0.21 wt. % MnO). In Zone II, olivine grains are notably less magnesian (Mg# = 81.8-84.1) and invariably have higher contents of manganese (0.19-0.30 wt. % MnO). The presence of this zoning is corroborated by the lateral distribution of accessory chromian spinel grains with maximum Mg# values (>20) in Zone I. The Khanlauta rocks also contain subordinate orthopyroxene (Mg# = 86.3-87.2), amphiboles of the tremolite-actinolite series, and anthophyllite of deuteric (autometasomatic) origin along with accessory minerals: ilmenite, hematite (~15 mol.% escolaite, Cr₂O₃, in solid solution), and mono- and diphase grains of sulfides in the form of intergrowths of Co-bearing pentlandite (Ni/Fe = 0.9-1.3; 1.00-16.74 wt. % Co; up to 1.7-6.8 wt. % Cu) and heazlewoodite (locally in intergrowth with hematite). The inferred front of crystallization moved in the western direction, causing the formation of Zone II from a more fractionated melt with a notably lower Mg# value. A sharp increase in oxygen fugacity locally caused the formation of anomalous parageneses of chromite and ilmenite, in which the observed Mg# values of ilmenite are considerably greater than those of the coexisting chromite. The geochemical whole-rock characteristics based on major, minor, and trace elements (including LILE, REE, and HFSE), as well as the compositions and trends of chromian spinels, are similar to those in differentiated (zoned) sills of the Chapesvara complex, which are closely associated with the Pados-Tundra layered complex. The obtained data indicate comagmatic relationships among the Khanlauta massif, zoned sills of the Chapesvara complex, and the Pados-Tundra layered complex. All of them crystallized from a primitive highly magnesian Fe- and Cr-enriched komatiitic magma (Al-undepleted). Thus, they belong to a single subvolcanoplutonic association being part of the Serpentinite belt-Tulppio belt (SB-TB) megastructure of presumably Paleoproterozoic age.

Mantle xenoliths of fresh sheared and granular peridotites from the Udachnaya kimberlite pipe (Yakutian kimberlite province, Siberia, Russia) are studied in terms of mineralogy, chemistry, and behavior of platinum-group elements (PGE), with a focus on difference between the two types of peridotites and on the role of PGEs in their origin. The analyzed samples of sheared and granular peridotites differ in mineral-liquid equilibrium temperatures and pressures: 1230-1350 °C, 56-67 kbar inferred for the former and 750-1300 °C, 30-67 kbar for the latter. The contents of major oxides, trace elements, and PGEs differ both between sheared and granular peridotites and within each group. Some sheared and all granular peridotites are enriched in incompatible elements, have low percentages of clinopyroxene and contain garnet rich in middle rare-earth elements (MREE). These features result from interaction of the peridotites with melts and related fluids of presumably carbonate compositions containing incompatible elements in high abundances. Sheared peridotites were more strongly enriched and gained more Ca, Al, and Ti than the granular variety. On the other hand, granular peridotites have higher light REE (LREE) and lower heavy REE (HREE) enrichment, which may record compositional difference of metasomatic agents. Metasomatism acted in two stages: first silicate agents caused LREE enrichment and HREE depletion of melts and then the fractionated melts percolated through the mantle and affected the compositions of granular peridotites and, partly, sheared peridotites. The two types of peridotites differ also in PGE patterns, with largely variable Os-Pt concentrations in granular peridotite. This difference may be due to uneven distribution of the Os-Ir and Pt-Os-Ir intermetallic compounds, which formed as sulfide melting residue in the lithospheric mantle. Sheared peridotites show almost uniform Os-Pt distribution and are enriched in Pd, Re, and partly Pt. The enrichment possibly occurred during metasomatism when the percentages of garnet and clinopyroxene increased while sulfide phases precipitated into interstitials.

Based on the analysis of the petrographic and lithogeochemical features of the Middle Jurassic-Lower Cretaceous strata in the lower reaches of the Anabar River, we have studied the regularities of changes in the composition of the upper parts of the Yuryung-Tumus and Sodiemykha Formations and the lower part of the Buolkalakh Formation. It has been established that the silt-sandy rocks of the first and basal beds of the second formation are graywacke arkoses and essentially feldspathic varieties, and most of the Sodiemykha Formation is composed of quartz-feldspathic and scarcer feldspar-quartz graywackes. A chemical classification of the rocks was made; most of them were assigned to normosiallites. The rocks of the marker beds, namely, the Fe-containing deposits of the Sodiemykha Formation, the basal glauconite bed of the Buolkalakh Formation, and the overlying clay bed, were classified as hypohydrolysates. All the studied deposits are of low sedimentary maturity, with essentially petrogenic clastic material. These are predominantly igneous rocks of intermediate and, less, felsic composition. The provenances were characterized by moderate chemical weathering. In the periods of the formation of the marker beds, chemical weathering intensified, and the amount of mafic and, partly, ultramafic rocks increased. The established changes in the composition of the parental strata are observed in the Middle Jurassic-Lower Cretaceous deposits of the entire considered petromineralogical province, which permits them to be used for correlation.

The paper is concerned with a study of the slope deposits being weathering products of rhyolites and their tuffs in the vicinity of Lake Grand (northern Okhotsk area). The samples were divided into grain size fractions of 2500, 250, 140, 100, 63, 40, 20, and 1 µm. Analysis for major and trace elements and mineralogical and petrophysical studies were performed for each fraction. It is shown that a decrease in the fraction size is accompanied by the enrichment of the sediments with Al₂O₃, Fe₂O₃, TiO₂, MgO, Y, Rb, Ni, and paramagnetic minerals and by an increase in LOI. The fine fractions are characterized by low contents of SiO₂ and Na₂O and high values of CIA, PIA, and Rb/Sr. The maximum magnetic susceptibility, saturation magnetization, and contents of CaO, Sr, and Zr are established in the fractions of 40 μm. The values of magnetic susceptibility, J_s , and J_rs decrease in passing from the fractions of 40 μm to the fractions of 1 μm, whereas the values of B_c and B_cr increase. A specific feature of these fractions is high paramagnetic susceptibility and the presence of lepidocrocite. The qualitative composition of ferrimagnetic minerals is the same for the slope deposits and lacustrine sediments. In passing from coarse fractions to fine ones, the contents of quartz and K-feldspar decrease, and the contents of muscovite, biotite, chlorite, and kaolinite increase. The distribution of petromagnetic and geochemical characteristics in the Lake Grand sediments of varying grain size is similar to that in the slope deposits. The complex characteristics of the lacustrine sediments that formed in cold and warm periods are consistent with the distribution of these parameters in various fractions of deluvium and colluvium. Moreover, the fine-grained material acquired specific geochemical, mineralogical, and petrophysical properties when being on the slopes. Comparison of the SiO₂/TiO₂ and Fe₂O₃/TiO₂ ratios of the slope deposits and lacustrine sediments makes it possible to identify the intervals of biogenic and chemogenic sedimentation in water basins.

The paper presents the results of the development and use of numerical methods for interpreting logging data in the Bazhenov Formation interval (Upper Jurassic). We consider wells located in the central and southeastern regions of West Siberia. Based on the machine learning method (artificial neural networks) and with the results of detailed lithological and geochemical core studies taken into account, a computational algorithm has been developed and tested to evaluate the material composition of the Bazhenov Formation rocks. In the studies we use the classification of the Bazhenov Formation lithotypes, which is based on the modern concept of the distribution of rock-forming mineral and mineraloid components. In the examined well sections, the lithologic composition of the Bazhenov Formation rocks has been determined, along with its lateral change in the central part of the Salym field, in the Surgut arch region, and in the southeast of West Siberia.

New insights in the aeromagnetic data over the Central Iranian Microcontinent (CIM) have revealed interesting results for future studies and exploration. This work presents the interpretation of different magnetic analyses and the calculated 3D inversion model to provide important insights into the distribution of igneous rocks in the area that may be traced under significant cover. By analyzing several hundred magnetic susceptibility data points and aeromagnetic anomalies of known igneous rocks over the area, it was determined that mafic-ultramafic intrusive rocks generally have a high magnetic susceptibility and produce a strong magnetic response. Intermediate-felsic intrusive rocks have a low magnetic susceptibility and show a smooth gradient variation and commonly regular shape. Volcanic rocks show a wide range of magnetic susceptibility; therefore, the aeromagnetic anomalies are often random or show strong amplitude with high frequency signals and are rapidly eliminated when an upward continuation is applied. Based on the results of analysis of different magnetic maps and 3D inversion of data, and combining this information with known outcropped of igneous rocks, we revealed 1215 concealed intrusive rocks and 528 volcanic rocks in the area. We also renewed the boundaries of tens outcropped igneous rocks. The known and new mapped igneous rocks can be identified as 12 regions (or zones) for intrusive rocks and 4 regions for volcanic rocks. The results indicate that the mafic-ultramafic rocks are mainly located in the Sistan suture zone of eastern Iran along the Nehbandan fault zone. They also show that the many parts of the Lut block as the main structure of CIM have been under magmatic events, so that most of concealed igneous rocks are distributed in the middle and southern part of the Lut block. Volcanic rocks are widespread in the southeastern and northern parts of the area such as the Urumieh-Dokhtar Magmatic Arc, North Lut, and Bam region.

The latest results on electromagnetic geothermometry and its use in geothermics and geothermal exploration have been covered. Temperature models for the well-known geothermal areas, Larderello-Travale (Italy), Soultz-sous-Forêts (France) and Hengill (Iceland), constructed from electromagnetic sounding data and temperature well logs have been analyzed. 2D temperature model built along the magnetotelluric profile crossing the Travale (Italy) geothermal system allowed to locate a potential supercritical reservoir at the depth between two isotherms, T_SCF ~ 400 °C and T_BDT ~ 600 °C, coinciding with the seismic reflectors, detected earlier. 3D temperature model of the Hengill (Iceland) geothermal area built up to the depth 20 km, using electromagnetic sounding data, allowed us to locate high-temperature magma pockets at shallow depth (2-5 km); these magma pockets can be regarded as targets for geothermal exploration. Joint analysis of the specific resistivity and temperature models, taking into account gravity anomalies, allowed us to locate the zones of different thermal regimes within the crust; this, in turn, explained the observed seismicity pattern by thermo-mechanical properties, rather than by crust spreading. Deep temperature model, built for the Soultz-sous-Forêts (France) geothermal area from magnetotelluric data and temperature well logs, used to locate deep heat sources and predict heat transfer mechanism at depth up to 8 km.

The results of numerical simulation based on the Mie theory of the superresonance effect in a dielectric sphere with a low refractive index are presented. Water was used as the material of the mesoscale sphere. It is shown that not only the previously studied weakly dissipative mesoscale spheres made of a material with “medium” (~ 1.5) and high (> 2) refractive indices, but also with a low one (~ 1.3) support the high-order Fano resonance effect associated with internal Mie modes. In this case, the intensities of resonant peaks for both magnetic and electric fields can attain extremely high values on the order of 10⁶-10⁷ in the vicinity of the poles of a water droplet with a Mie size parameter of ~ 70.

The paper presents the results of complex experimental studies of gas impurities and the vertical structure of aerosol in the atmosphere over Lake Baikal in September 2021, using the research vessel (RV) "Academician V.A. Koptyug". Measurements of gaseous impurities in the near-air layer were carried out using local control means - chemiluminescent gas analyzers. The sounding of aerosol fields was carried out using a multi-frequency polarization aerosol-Raman lidar "LOSA-A2". Compared to previous expeditions, in 2021, low concentrations of gaseous impurities and aerosols, close to the background ones, were recorded. The analysis showed that the main contribution to atmospheric pollution was made by nearby local sources located near the coastal zone of the lake.

The approbation results for the algorithm of detecting specularly reflecting layers in high-level clouds based on passive satellite data are presented. We consider cirrus clouds with an optical thickness of less than 5 and a top height of more than 8300 m consisting of horizontally oriented ice crystals, observed over the territory of Western Siberia from 2006 to 2007. The technique for detecting specularly reflecting layers in high-level clouds is described and the statistical analysis of their parameters is performed on the basis of spectroradiometer MODIS satellite data. We discuss the seasonal and latitudinal properties of the parameters of considered clouds over Western Siberia..The typical values of the area, top height, reflection ratio, and effective emissivity of specularly reflecting layers over different latitudinal zones of the target region were estimated for the first time.

In this work, the long-term series of vertical stratification of aerosol in the stratosphere are processed and analyzed with the use of the scattering ratio as an example, as well as the vertical distribution of aerosol scattering coefficients at a wavelength of 532 (altitude range 15-50 km) over Tomsk. The experimental data were received from regular measurements at the lidar station of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, in 2010-2021. On the basis of the accumulated experimental material, regional features of the intra- and interannual variability of the stratospheric aerosol in Western Siberia were revealed. An optical-aerosol model of the atmosphere is suggested for this region, more adequate to actual conditions are compared to existing ones.

Possibilities of wind speed measurement in the atmospheric layer from 10 to 20 km with a ground-based pulsed coherent Doppler lidar (PCDL) operating on molecular light scattering are numerically studied. Requirements for the parameters of PCDL with sounding radiation wavelengths of 1 and 2 mm for receiving reliable information about the wind speed and direction in the atmospheric layer under study are determined in numerical experiments.

The reasons are found for a decrease in the sensitivity of a TROA (time-resolved optoacoustic) detector in spectrometers with pulsed lasers and of a non-resonant OA detector in spectrometers with cw lasers when buffer gas nitrogen (air) is replaced by hydrogen in mixtures with an absorbing gas. In the first case, the reason is the high speed of sound in hydrogen at an insufficiently wide working frequency band of the microphone. In the second case, the reason for the loss of sensitivity is the low dynamic viscosity of hydrogen, which results in faster pressure equalization in the pre- and behind-membrane volumes of the OA detector chamber for a light pause as compared to heavier molecular gases. Therefore, the amplitude of an OA signal at the modulation frequency of the cw laser radiation increases in proportion to the dynamic viscosity of the gas.

The mixed moments of wind vector components on the turbulent and meso-gamma scales calculated from experimental data obtained in the surface air layer at an altitude of 10 m are compared. The statistics of mixed moments for several months in different seasons of 2021 is presented. The dependence of mixed moments on the wind velocity and temperature stratification in the surface air layer is briefly analyzed. The values of mixed moments formed by the wind field components on the meso-gamma scale are comparable with those formed by the mixed moments of turbulent components of the wind vector.

The simulation results the radiative forcing of smoke aerosol (RFA) at the boundaries of the atmosphere are considered depending on the photochemical evolution of its organic component, illumination conditions, and underlying surface types (water, mixed forest, and snow/ice). An increase in the albedo of the underlying surface and a decrease in the aerosol optical depth can lead to the transformation of the cooling effect into heating at the top of the atmosphere. An increase in the absorbency of aerosol particles is the cause of an increase in RFA at the top of the atmosphere, which is most significant over snow/ice surfaces, while at the bottom of the atmosphere, RFA decreases. As the solar zenith angle increases, the absolute value of RFA decreases as the smoke plume propagates over weakly reflecting surfaces, but with an increase in the albedo of the underlying surface, this dependence transforms into a nonmonotonic one. It is shown that neglecting the transformations of the optical characteristics of organic aerosol can lead to overestimation or underestimation of the radiative forcing of the aerosol at the top of the atmosphere by several times (by several tens of W/m²), and also cause an error in determining the RFA sign.

Here we discuss methodological aspects and approaches to solar radiation measurements at the Fonovaya Observatory of IAO SB RAS, as well as capabilities of the new radiation unit mounted there in 2020. It is equipped with a set of instruments which allow continuous monitoring of the total (0.285-2.8 mm), total UV (0.280-0.400 mm), and UV-B radiation (0.280-0.315 mm) and the energy balance between incoming short-wave and long-wave far infrared radiation. The capabilities of measurement data collecting, transmitting, and processing of the specially developed software are described.

The design characteristics of the turbulent lidar affecting its thermo-mechanical stability are determined. A comparative description of two different designs is given, where different approaches are implemented to the selection of transceiving optics and receiver detectors and organization of the temperature control system for stabilizing the lidar optical bench. A simulation scheme of a lidar transceiver is suggested, including the calculation of the displacements of optical elements relative to the base points on the optical bench and the ray tracing from the laser into the atmosphere and back. The influence of the temperature gradient between the opposite sides of the optical bench on the operation of the receiving channels is considered. The results of the experimental study of lidars for resistance to temperature changes are presented. Recommendations for improving the design of a turbulent lidar are formulated.

The conditions for generation of red streamers at an atmospheric air pressure of 0.1-10 Torr are experimentally studied. The mode of generation of streamers tens of centimeters in length from the plasma of an electrodeless capacitive discharge is implemented under low pressures. A discharge between metal small-curvature electrodes transforms into a stationary mode, where streamers are not generated, as the pressure and voltage increase. It was confirmed using the ICCD camera that the streamers start from the positive-polarity electrode. The color of the discharge plasma depends on the air pressure in pulsed and continuous discharges and is most consistent with the color of red sprites at a pressure of ~ 1 Torr.

The CO₂ content in tree wood and the radial increment of trees can change under the impact of ground fires. The larch discs under study survived the fire of 1908 after the explosion of the space body in the Podkamennaya Tunguska revealed a number of features in the behavior of absorbed CO₂ and (CO₂ + H₂O) in larch wood. The photoacoustic analysis of samples vacuum-desorbed from tree rings has shown a long-term annual accumulation of CO₂ and (CO₂ + H₂O) in tree stems after 1908. A change in CO₂ release cycling in the post-catastrophic period is ascertained. A change in variation cycling is also noted in the tree ring chronologies. According to the analysis of the correlation coefficients, the specific behavior of the larch ring width chronologies in this region is most likely due to variations in the solar activity.

This paper presents the results of experimental panoramic measurements of the temperature field by a method based on the registration of laser-induced fluorescence of the hydroxyl radical (OH) upon excitation of two different transitions (two-line PLIF) in a laminar conical flame of a gas-droplet mixture of ethyl alcohol and air. Laminar flow of the uniformly mixed ethyl alcohol/air mixture with fine droplets is produced by an ultrasonic atomizer inside the liquid ethanol tank. The properties of the two-phase flow at the nozzle outlet without combustion was controlled by a time-of-flight optical sensor. The temperature field was estimated based on the excitation of the Q₁(5) and Q₁(14) lines of the (1-0) transition of the A²∑⁺ - X²π electronic system. The spatial unevenness of the energy distribution in the laser knife illuminating the central plane of the flame cone and the change in the pulse energy from frame to frame were compensated by the use of an additional camera recording the laser radiation intensity distribution in the calibration cuvette.

Structurally stressed hydrocarbons (SSHs) have improved energy performance compared to conventional liquid hydrocarbons. The ignition induction period of mixtures of SSH vapors with air has been studied as a function of temperature and excess air ratio. The results are compared with similar results for mixtures of vapor of n -alkanes with air. The ignition induction periods of mixtures of vapors of two SSH with air are determined. Data on the ignition delay of air-fuel mixtures are required to design engine combustors and to develop and evaluate the possibilities of using new fuels.

This paper presents the results of an experimental study of the characteristics of a swirling flow with the formation of vortex structures in a radial burner under isothermal and reacting conditions for various flow swirling parameters. For isothermal conditions, the distributions of average and fluctuating velocity fields, including those tied to the phase of a precessing vortex, are obtained, the pressure fluctuations induced by the precessing vortex are analyzed, and the contribution of the precessing vortex structure to the overall level of turbulence is determined. The studies are carried out using modern contactless experimental methods of flow diagnostics, such as optical imaging and particle image velocimetry (PIV). An acoustic field generated by the vortex core precession (VCP) is recorded using four measuring microphones with pressure taps. The contribution of the VCP to the overall level of turbulence is revealed using the method of proper orthogonal decomposition (POD), also applied to analyze the velocity distributions obtained by the PIV method. The experiments show that, in the isothermal case, the VCP that occurs after the twist parameter overcomes a value S = 0.6 is a single-helix vortex structure, whose contribution to the overall level of kinetic turbulence energy is up to 27 %. For reacting conditions, the flame is visualized at different flow swirls and the frequency characteristics of the VCP occurring in the flow at S ≥ 0.6 are measured. It is shown that the dependence of the dimensionless frequency of the VCP as a function of the flow swrl S has the same nonmonotonic character both in the case of combustion and in the isothermal case.

Results of studying kerosene combustion in constant-section channels for the Mach number at the channel entrance M = 1.7 are reported. The experiments are performed in channels with variations of the duct shape. The existence of flow regimes with wave structures that do not lead to the development of the pseudoshock mode of combustion is demonstrated. Critical conditions that have to be satisfied for initiation and realization of pre-detonation quasi-stationary combustion are determined.

Results of experimental investigations of the flow in a channel with sudden expansion without and with heat supply into a supersonic air flow are presented. Based on processing experimental data on the time evolution of static pressure on the channel walls, the spectral power of oscillations are determined. The analysis reveals an increase in the spectral power of pressure oscillations in the frequency range of 250 ÷ 400 Hz. The greatest increase in the spectral power is observed in the initial period of the process during ignition and at the end of flame stabilization. In the period corresponding to developed combustion, the peak value of the power spectrum of oscillations decreases, while the range of frequencies is extended to 400 ÷ 600 Hz.

Results of numerical simulations of turbulent reacting flows in a channel with sudden expansion with due allowance for injection of hydrogen jets into a supersonic (M = 4) air flow are reported. The simulations are performed in a three-dimensional unsteady formulation with the use of the ANSYS Fluent software under the test conditions of experiments performed in the IT-302M high-enthalpy wind tunnel. The computations predict a self-oscillatory regime with intense oscillations of pressure and integral heat release. The period-averaged pressure distribution is in reasonable agreement with the experimental measurements, and the frequency of pressure oscillations is within the range obtained in the experiments. Based on a detailed analysis of the flow characteristics within the full cycle of oscillations, the feedback mechanism responsible for the emergence of self-supported oscillations is refined.

Experimental data on the velocity of propagation of a combustion wave in a coal-methane-air mixture with respect to the walls of a closed channel for various concentrations of coal dust are presented. A physico-mathematical model of combustion of this mixture on the basis of equations of gas dynamics and mechanics of disperse media in the one-velocity one-temperature approximation is developed. In the proposed model, the velocity of propagation of the combustion wave with respect to the gas suspension and the burning rate of the coal dust particle are parameters of the model and are determined by providing the consistency between the computed and experimental results. A comparison of the calculated flame velocity with respect to the channel walls in a wide range of mass fractions of coal dust reveals reasonable agreement with the experiments. The proposed approach can be used for estimating the influence of coal dust combustion on the intensity of shock waves formed in coal mines in the case of accidental explosions of methane.

The influence of a relatively small additive of unsaturated gaseous hydrocarbon (propylene) on the detonation wave dynamics in a stoichiometric hydrogen-air mixture was studied by numerical simulation. The influence of the propylene concentration on the development of detonation in the mixture caused by direct initiation with an energy input from the outside in a small volume in a short time was studied at different initial temperatures of the mixture. A detailed mechanism of hydrogen combustion and key propylene hydrogenation reaction were used. Propylene is readily hydrogenated with the removal of atomic hydrogen from the reaction chain. This leads to an increase in the self-ignition delay of the mixture behind the leading shock wave, and at a sufficient concentration of the inhibitory additive, to the decomposition of the cellular detonation wave structure and detonation degeneration.

Interaction of a shock wave in a gas with a combustible gas bubble of an elevated density is numerically simulated based on the Euler equations. Three qualitatively different regimes of detonation initiation are described: direct initiation of detonation in the frontal part of the bubble at sufficiently high Mach numbers of the incident wave and detonation initiation in the rear part of the bubble due to wave refraction and focusing of secondary shock waves at lower Mach numbers. It is shown that the detonation initiation regime depends to a large extent both on the shock wave intensity and on the density of the mixture in the bubble. Based on a series of computations, a diagram of initiation regimes is composed. It is demonstrated that the effect of shock wave focusing ensures successful initiation of detonation with a much lower intensity of the incident wave as compared to direct initiation.

The flow in a combustion chamber in the form of an annular gap between plates with multi-headed rotating detonation has been studied numerically. It is assumed that a homogeneous propane-air mixture with given stagnation parameters enters the combustion chamber through elementary nozzles evenly filling the outer bounding ring. The gas-dynamic parameters of the mixture are determined as functions of the stagnation parameters and static pressure in the gap. The conditions for the formation of a given number of waves in the multi-headed detonation wave related to the dimensions of the combustion chamber and parameters of the initiators are obtained. The maximum number of waves for given dimensions of the combustion chamber are established. The existence of the maximum critical number of waves in multi-headed detonation is associated with blocking of the supply of the combustible mixture. Under the considered geometrical parameters of the flow region, one to eight rotating detonation waves are formed. It is found that in the case of an uneven arrangement of initiators, there is gradual alignment of the mutual angles between the waves making up the multi-headed detonation. Calculations were performed on the Lomonosov supercomputer at the Moscow State University using an original software package implementing a modified Godunov method and one-step reaction kinetics.

A new microwave technique for measuring the gasification rate in a non-stationary mode is described. A feature of the technique is that to determine the mass loss during gasification, the time-varying resonant frequency of the microwave resonator with the sample under study is measured by sequential registration of the resonant characteristics of the sensor. This provides independence of the measurement results from the change in the quality factor of the resonator during fuel sample gasification. A sensor prototype which is a coaxial resonator in which the sample under study is placed in the region of maximum electric field was tested. Experiments have shown that the sensitivity (the ratio of the change in resonant frequency to the change in the inner diameter of the sample) of the new sensor design is two to four times higher than that of the previous sensor model.

This paper presents results of an experimental study of the processes of thermal decomposition and ignition of high-energy materials (HEMs) containing an oxidizing agent, a combustible agent, and dispersed additives of aluminum, aluminum borides (AlB₂ and AlB₁₂), and amorphous boron. A Netzsch STA 449 F3 Jupiter thermal analyzer and an experimental testbench, which includes a continuous-wave CO₂ laser, are used to investigate the response and ignition characteristics of two basic HEM compositions based on AP/SKDM/Me and PCA/AN/MPVT/Me at different heating rates. It has been established that ammonium nitrate at low heat flux densities (q < 130 W/cm²) decomposes and melts, forming a liquid layer on the reaction surface and increasing the delay time of the emergence of a HEM flame containing Al, AlB₂, and AlB₁₂. With an increase in the heat flux density, the effect of the liquid layer on the reaction surface of the sample decreases due to the rising surface temperature, the outflow rate of gaseous decomposition products, and the layer evaporation.

Intermountain basins in Khakassia and southern part of the Krasnoyarsky Krai represent an interesting steppe region of Russia. This territory extends in the latitudinal direction for more than 350 km - from the Arga ridge in the north to the piedmonts of the Western Sayan in the south. As in many mountainous steppe and forest-steppe regions, four environmental gradients are responsible for vegetation patterns: moisture, stoniness, salinity, and sand content in soils. The high diversity of habitats is the reason for the high diversity of plant communities and species, among which there are many endemics. In numerous publications, since 1998, 22 associations have been given for the studied territory. Ecological analysis of these associations using plant indicator values (Korolyuk, 2006) showed that some of them do not differ in position on the main gradients. This requires an explanation and analysis of differences in floristic composition of syntaxa. The purpose of the work is to revise current syntaxonomical scheme of Nazarovsko-Minusinskaya intermountain depression using formalized methods or relevés analysis.

The main floristic differences of meadows of West Siberia plain, and of Altai-Sayan mountain region were revealed to be geomorphologically determined. The concept of syntaxa-“cores” uniting moderately disturbed meadows has been formulated. Their areas correspond to 5 geomorphological regions: the forest zone of West Siberian Plain, the northwestern foothills of Altai-Sayan mountain region, hyperhumid low mountains, hyperhumid middle mountains, and humid middle mountains. Dissimilarities of meadows in one region are caused by edaphic and anthropogenic factors, i.e. the recent fallow past, long-term overgrazing, relatively poor soils, periodically over wetted habitats, slightly salinized habitats. Taking into account the above ideas, the scheme of floristic classification has been corrected. The phytocoenotic diversity of studied area meadows is represented by 21 syntaxa belonging to 16 associations and 9 subassociations of 2 alliances from 2 orders of the Molinio-Arrhenatheretea class. Short descriptions of these syntaxa have been carried out. 15 syntaxa have been described for the first time or validated.

We studied the seed set of a perennial herbaceous short-rhizome polycarpic plant Galeobdolon luteum (yellow archangel) in open pollination and various options of mechanic pollination (bag directly, parthenogenesis test, cross pollination). Our surveys were carried out in 2020-2022 according to generally accepted methods in natural conditions of the Moscow region. It has been shown that G. luteum produces from 48 to 128 ovules and from 10 to 108 completed seeds per one shoot. In natural pollination, we found only two variants of coenobia (schizocarpic fruit): completed seeds are not formed in the fruit at all, or the fruit includes 4 fully formed nutlets. Our studies did not reveal the ability for apomictic seed setting in this species. In flowers of G. luteum, autogamous pollination is possible with rather sharp and significant fluctuations of flowers under the influence of various environmental factors (gusts of wind, raindrops, etc.). It was revealed that within the inflorescence of G. luteum, with simultaneous flowering of several flowers, geitonogamy is possible due to the presence of a self-compatibility system and visiting flowers by pollinating insects. In abundant cross pollination, the seed set of G. luteum is higher than in open pollination, which is due to the ingress of a larger number of pollen grains on the stigmas of flowers than with insufficient pollination carried out by insects.

On the basis of 25 years of observations (1990-2014), the types of ecological-cenotic strategies have been determined for laxicaespitose grasses Arrhenatherum elatius and Dactylis glomerata on spoil banks in the Kuznetzk Basin. In 1989-1990, seven agrophytocenoses were created on levelled open-cut spoil banks of “Listvyanskiy” coal mine. Seeding of D. glomerata and A. elatius was carried out on Quaternary and Perm deposits as a part of mixtures of grasses or grasses with legumes. Determining ecological-cenotic strategies was based mainly on revealing the following aspects: above-ground phytomass, projective cover, lifespan, hummock size, numger of generative shoots, ontogenetic spectrum. D. glomerata acts as a violent species in the grass mixtures on deposits of different geological age for the initial 14 years. But D. glomerata is an ecotopic patient species in the grass mixture with Onobrychis arenaria, in sowing with Trifolium pratense, and in the thickened clover-grass mixture (with a higher seeding rate). A. elatius acts as violent species in the grass mixtures on deposits of different geological age for the initial 4-5 years after seeding. During the subsequent years in the grass mixtures, as well as for all years in the mixture with Onobrychis arenaria, A. elatius acts as a phytocenotic patient species. The following features were also noticed. Both species, D. glomerata and A. elatius, persisted in all communities for all years of observatioin. The generative shoots of D. glomerata were emerging rather late, for the 3-4 years of life, which guaranteed fruiting of the shoots. For both species, the ontogenetic spectra laked the senile individuals (and for and A. elatius even the subsenile ones). In particular years, A. elatius was producing large quantities of generative shoots, about 100 per m²; and the numbers of individuals per m² were reaching 800 on account of seedlings.

Data on the species diversity of representatives of the genus Pseudokephyrion Pascher in water bodies of Western Siberia, their distribution by zones and subzones are summarized. To date, 17 species and intraspecific taxa are known for the region, represented by 16 species of the genus Pseudokephyrion from the Dinobryaceae family. Representatives of this family are found in mosaics throughout Western Siberia. A greater number of species (12) were found in the middle taiga; 11 taxa were identified in the forest-steppe zone; in other zones, the number varied from 1 to 5. No species were found in the steppe and forest-tundra. In lakes and streams of various types, 14 species of this genus were identified. To date, 11 species of this genus are known in the watercourses and reservoirs of the Siberian Uvaly Natural Park.

The results of a taxonomic analysis of the lichen flora of the North-Eastern Okhotsk region (Magadan Region), which currently includes 412 species belonging to 1 division, 1 subdivision, 4 classes, 5 subclasses, 15 orders, 45 families and 133 genera, are presented. The majority of the species belongs to the class Lecanoromycetes (404 species or 98 %), which is represented by 4 subclasses - Acarosporomycetidae, Lecanoromycetidae, Ostropomycetidae and Umbilicariomycetidae. The basis of the lichen flora is represented by the Lecanorales order, which unites 10 families, 53 genera and 190 species (46 % of the total species diversity). The average number of species in the family is 9.2 in the studied lichen flora. The level of species richness exceeding this indicator belongs to 12 families, numbering a total of 313 species or 76 % of the flora. The average number of species in a genus is 3. In the studied lichen flora, 24 genera have an indicator higher than this value; they include 235 species or 57 % of the total flora. The largest genus Cladonia in the lichen flora of North-Eastern Priokhotye includes 44 species. The spectrum of the leading families of lichen flora is typical of the lichen flora of the Boreal zone of the Holarctic. Boreal features are indicated by the leading position of such families as Parmeliaceae, Cladoniaceae, Physciaceae, Lecanoraceae, Peltigeraceae, genera Cladonia, Peltigera. The high position in the spectrum of the families Rhizocarpaceae, Umbilicariaceae, Stereocaulaceae, Lecideaceae, including epilithic species, indicates the mountain character of the lichen flora. Thus, the studied lichen flora should be characterized as mountain-boreal.

The article presents a brief autobiography and scientific activity of Alexey Gorbunov, a leading researcher at the Central Siberian Botanical Garden of the Siberian Branch of the Russian Academy of Sciences. The main results of scientific activity are lightened and prospects for further research are outlined.

With an increase in energy consumption, more and more attention is being paid to nontraditional energy, including natural resources of thermal springs. Along with the problems of using thermal waters, their search is an important task. The experience of analyzing maps of plastic relief for the detection of thermal springs, obtained by using the example of the south of Kamchatka, is presented. Linear and ring-shaped zones of tension of the Earth’s crust were identified according to the maps of the relief plasticity. Of particular interest are the intersections of linear and ring structures. There arise zones of increased fracturing of rocks, within which active and extinct volcanoes and thermal springs are located. A map of promising sites is presented, the development of which in the near future will make it possible to solve the problems of energy consumption in an environmentally safe way, expand the geography of tourism and spa balneology. This will give an impetus to the development of the entire region as a whole. The experience of analyzing relief plastic maps in order to detect thermal springs can be applied throughout Russia in the future, including when searching for ore deposits.

The problem of forest degradation caused by high growth rates of population is considered by using the Anuppur District (India) as an example. It is shown that the study area is faced with a significant reduction in the forest area due to a rapid population increase and an enhancement of economic activities. In 1981, the area occupied by forests in Anuppur was estimated at 129 885 ha (the area of the district totaling 374 671 ha), whereas it decreased to 76 448 ha in 2011. For the same period the population increased from 418 731 to 749 237. We identified a feedback between the population and the status of forests in the study area. Many kinds of economic activities (agriculture, construction of settlements, motor roads and railroads, engineering structures, development of mineral resources in the forest zone, etc.) are carried out in an unsupervised manner, which leads to a reduction of forest areas, loss of biodiversity of forest ecosystems, and to other ecological problems. Recommendations are made for improvement of forest management in order to increase sustainability of forest ecosystems as well as to meet the needs of the economy and population of the district for various forest resources.