Home – Home – Jornals – Atmospheric and Oceanic Optics 2025 number 4

We present new data on the composition and U-Pb (LA-ICP-MS) age of detrital zircons from the Carboniferous sedimentary rocks of the Siberian Platform cover, in which diamonds and accessory minerals were found, namely, the Baeronovka Formation in the southwest and the Tushama and Kata formations at the center of the Siberian Platform. The geochemical characteristics and results of analysis of minerals of the heavy fraction from the Baeronovka Formation indicate a predominantly felsic composition of the provenance rocks. The latter are, most likely, the rocks of the Cis-Sayan uplift of the Siberian Platform basement, including mostly Paleoproterozoic granitoids and volcanic rocks of the South Siberian postcollisional magmatic belt. Smaller amounts of detrital material got into the sedimentation basin of the Baeronovka Formation through the destruction of early Paleozoic rocks at the northern segment of the Central Asian Orogenic Belt. The geochemical characteristics of the terrigenous rocks of the Carboniferous Tushama and Kata formations testify to a felsic composition of the provenance rocks, but the mineral compositions of the heavy fractions indicate different compositions of these rocks. These data and the age of detrital zircons suggest that the Neoproterozoic sedimentary rocks and middle Paleozoic igneous rocks of the Baikal-Patom zone on the southern margin of the Siberian Platform and the Middle Paleozoic igneous rocks of the Vilyui rift and the Yakut diamondiferous province are the main provenances for the Tushama and Kata formations. The established differences in the composition and age of provenance rocks for the Carboniferous sandstones of different areas of the Siberian Platform confirm the earlier conclusions about the existence of several local sedimentary basins within it in the Devonian-Carboniferous. These basins formed after the middle Paleozoic tectonomagmatic activity accompanied by diamondiferous lamproite and kimberlite magmatism.

Three midocean ridges meet in the Bouvet triple-junction region: Mid-Atlantic, Southwest Indian, and American-Antarctic. The triple-junction region is indicated by the Bouvet hotspot magmatism. Available laboratory modeling data are applied to construct a diagram showing the conduit of a thermochemical mantle plume melting from the core-mantle boundary and erupting onto the surface. Morphobathymetric data for the Bouvet Island region are used to obtain the mass flow rate of magmatic melt for the Bouvet plume. Considering the calculated melt flow rate, the thermal power of the Bouvet plume source is N _B = (1.7-2.0) ·10¹⁰ W, and the plume conduit diameter is 9-16 km. Possible evolution of the Bouvet plume is presented on the basis of consideration of its geodynamic regime. The influence of the geodynamic system of asthenospheric convection flows on the ocean floor structure in the Bouvet region is shown. The plume under whose influence Bouvet Island formed is located in the region of the ascending asthenospheric roll flow and locally intensifies it. Transform faults in the Bouvet region were formed under the influence of descending asthenospheric roll flows. The width and the depth of the trough of the Bouvet transform fault are determined by analyzing the flow structure and heat transfer in the asthenosphere in the Bouvet region and with regard to the intensifying effect of the Bouvet plume on the ascending asthenospheric roll flow. The conducted geochemical and thermobarogeochemical studies indicate the decisive role of fluid components in the magmatic systems of the Bouvet hotspot, which are characterized by enrichment in volatiles (H₂, H₂O, and CO₂) and alkalis (primarily potassium) as well as lithophile rare and rare-earth elements (La, Ce, Th, Nb, and Rb). In view of the seismic tomography results, the features of the mantle structure in the triple-junction region are considered. A high-velocity anomaly is identified along the axial zone of the Bouvet transform fault, and the roots of this anomaly in the upper mantle are traced to a depth of 250 km. A low-velocity anomaly is revealed under Bouvet Island, which is traced to about 500-km depths.

The paper considers the age, composition, and genesis of granitoids of the Soktui massif, a petrotype of the Kukul’bei Complex of Mesozoic rare-metal granites in Transbaikalia. The Soktui massif is heterogeneous; it comprises several petrographic varieties: monzogranite-monzoleucogranites and microleucogranites of the major intrusive phase and alaskites, alkali-feldspathic granite porphyry, granodiorites, and quartz syenites of the phase of additional intrusions. According to the obtained U-Pb geochronological data, the ages of all varieties are the same within the analytical error and correspond to the Early Cretaceous. The granitoids are diverse in geochemical characteristics: The monzogranite-monzoleucogranites of the major intrusive phase belong to the rare-metal plumasite type, and the rocks of the phase of additional intrusions show signs of A -type granitoids. The geochemical and isotope characteristics of the rocks confirm the contribution of both continental crustal substrates and deep-seated mantle-derived magmas to their formation. The contents of volatiles in micas and the composition of fluid and melt inclusions indicate the involvement of two types of fluids in the magma generation: reduced chloride (probably mantle) and more oxidized fluoride (presumably of lower-crust origin). All melts were generated at depths of no more than 30 km, and the depth of the massif formation was shallower than 8 km. Based on the obtained data, we propose a model for the formation of the massif rocks.

We have studied the macrocomponent composition of pore solutions in hydrothermal clays forming extended thick strata in the thermal fields of the Pauzhetka geothermal system. Two zones have been identified in the vertical sections of the clay strata, which differ in the physicochemical parameters, composition, and formation conditions of pore solutions. It is shown that the pH of the solutions plays a crucial role in the change of their macrocomponent composition with depth. The conclusion is drawn that the pore solutions resulted from the direct impact of deep-level infiltrating thermal waters on the matrix of hydrothermal clays, which led to the redistribution of elements between the rock and the contact solution. Along with the general regularities, we have established significantly different conditions of formation of pore solutions in the Upper Pauzhetka and East Pauzhetka thermal fields, which is due to the different geologic positions and hydrogeochemical regimes of these fields.

Sulfosalts of the tetrahedrite and enargite groups from the Maletoyvayam epithermal Au-Ag deposit were studied using optical and scanning electron microscopy. We conclude that they were crystallized from acidic magmatic volcanogenic hydrothermal fluids under conditions of elevated oxygen level. Early sulfosalts of the pre-gold stage of the Maletoyvayam deposit, argentotetrahedrite-(Zn,Fe) and tetrahedrite-(Zn,Fe), associated with pyrite, arsenopyrite and galena, evolved with their enrichment in Te, Se and Cu. Increased activity of these elements caused by an increase in the oxidation potential of the environment led to the crystallization of subsequent stibiogoldfieldite, arsenogoldfieldite, and minerals of the enargite group, where the excess Cu content increased as the ore-forming system evolved. Au-bearing minerals are paragenetically associated with sulfosalts of the final stage of this evolution. The crystallization trend of sulfosalts (As→Sb→Te) at the Maletoyvayam deposit is also characteristic of other acid-sulfate type deposits, such as the Ozernovskoe and Prasolovskoe deposits, in contrast to the reverse trend (Te→Sb→As) typical for sulfosalts from adularia-sericite type epithermal Au-Ag deposits.

Active faults under permafrost conditions in the highland part of Gorny Altai (South Chuya and Kubadru fault zones) and the Lena River delta (Primorsky Fault Zone) were studied using the electrical resistivity tomography technique. The method proved to be effective in identifying active fault zones to depths up to the first hundreds of meters under permafrost conditions. However, the presence of ice-rich rocks with a resistivity greater than 100 kΩ·m limits its application because of the screening effect of the insulating unit. The main criterion for identifying active faults in geoelectric sections is the existence of subvertical zones of reduced electrical resistivity against the background of high-resistivity permafrost rocks. This concerns both the young seismic ruptures formed during the 27 September 2003 Chuya earthquake ( M_s = 7.3) in the South Chuya Fault Zone and the older Holocene primary seismic deformations in the zones of the Kubadru and Primorsky faults. At the same time, the electrical resistivity values in the zones of active faults and seismic ruptures are too high to assume their saturation with free water. The decrease in electrical resistivity in such zones relative to the host permafrost frame may be due to (1) intensive fracturing of rocks and sediments; (2) occurrence of finely grated material in the core and damage fault zones, on particles of which adsorbed unfrozen water is concentrated; (3) residual thermal anomalies in the case of modern fault activations, so that negative temperatures have already been restored, but the process of frozen strata aggradation is not complete yet; (4) saturation of the geologic section with sand-silty material as a result of liquefaction and fluidization processes during earthquakes. The revealed regularities can be used not only to confirm the zones of morphologically distinctive segments of active faults but also to search for their buried segments in the permafrost areas typical of seismically active highland and Arctic regions in Russia and worldwide.

The article considers the results of mathematical modeling of transient electromagnetic cross-borehole monitoring data for civil and industrial cryolithozone facilities containing thaw zones (taliks) in their vicinity. A solution to the direct problem is presented based on the Sumudu integral transform and the vector finite-element method for two types of borehole sources: induction coils and a less common electric current line, taking into account the frequency dispersion of the electrical conductivity of permafrost. Three-dimensional numerical modeling of the transient signals is performed in realistic geoelectric models of a gas-producing borehole and a residential building on piles. Based on the modeling results, we have revealed the main features and differences of transient cross-borehole monitoring with coils or a line as the source.

The use of microgrids is a relevant direction of energy development both in Russia and abroad. At the same time, problems arise in selecting an optimal structure and operating parameters of such networks. Conducting full-scale experiments with a real energy complex involves certain risks associated with high time and financial costs, as well as the reliability and safety of its equipment. Therefore, studies are usually carried out on mathematical or physical models of a microgrid. A physical model allows solving a number of important problems. These include the analysis of the network structure, the study of its main characteristics (resilience, reliability, regulation of demand and supply of energy resources, use of renewable energy sources, and other features) and the determination of optimal operating modes. The paper considers a monitoring system for a physical model of a microgrid (a simulation stand that simulates a network with a high share of renewable energy sources).

A method and technical instrumentation are proposed for estimating the sizes of vortex structures generated in the annular gap of a Couette - Taylor system. The size estimation of these structures is based on analyzing the measured amplitude-frequency spectra of radial dynamic pressure pulsations. A simplified model of vortex generation in the Couette - Taylor annular flow, driven by the rotation of the inner cylinder surface, is introduced. Using this model and the measured amplitude-frequency spectra of radial pressure pulsations, the sizes of the generated vortices in the Couette - Taylor flow are evaluated. The results reveal three distinct types of vortices: vortices with diameters significantly smaller than the annular gap width, vortices with diameters comparable to the gap width, and vortices with diameters substantially exceeding the gap width, leading to their deformation (flattening).

The paper presents a gradient boosting-based machine learning model developed to predict the occurrence of defects (dross) on galvanized steel sheets used in the automotive industry. An analysis of the influence of process parameters on the occurrence of defects is carried out, which makes it possible to identify the key factors affecting the quality of the coating: coil rolling speed, elongation and force in the coil-scin pass mill, zinc coating at top, temperature in the galvanizing pot, and temperature in the furnace snout. Based on the results of the study, a digital assistant is developed for evaluating coils in real time, providing simulation of the decision-making process and helping in prompt managing of the technological process.

The article presents modifications to the Sardana software package for automating synchrotron radiation experimental stations. These modifications are aimed at achieving the nominal accuracy of positioners, reducing the time consumption with the minimum operator supervision. In addition, these modifications simplify conducting standard experiments and provide greater flexibility in configuring experimental setups. They are applied to the automated control system of the sample environment at Experimental Station 1-1 "Microfocus."

The article problem of optimal performance for a process described by a system of nonlinear differential equations is considered. To determine an approximate solution to the problem, it is proposed to apply the evolutionary method of artificial immune systems, which offers an advantage of the lack of sensitivity to the choice of the initial approximation. To find a numerical solution to the problem of optimal performance, a step-by-step algorithm is formulated, whose operation is tested on a model problem. Suboptimal control in terms of response time is obtained, and the algorithm parameters are determined that allow one to calculate the problem solution with the least computational costs. The efficiency of the developed algorithm is demonstrated by comparing the results of numerical calculations with the results of applying the fixed-point method.

A parametric identification problem of a linear dynamic SISO plant under incomplete a priori information based on the least squares method is considered At the stage of formation of the system of equations, a special type of the forming function is used. It allows the numerical differentiation of the measured input and output signals of the identified plant to be replaced by multiple application of integration by parts. The dependences of the frequency properties of the forming function and its derivatives on the function parameters are obtained in analytical form. The paper presents results illustrating almost complete coincidence of the frequencies obtained both experimentally and analytically.

We develop a theory of the ferroelectric polarization reversal taking into account conduction of domain walls. The case of capacitor geometry is considered as applied to lithium niobate. We show that the field dependence of the domain nucleation rate obeys the law exp(-E_n/E ), where E is the applied field and E_n ≈ 10² kV/mm is the characteristic field controlling the domain nucleation process. For the critical domains, the longitudinal size l^*_c strongly exceeds the transversal size 2l^*_a ≈ 1 nm. We formulate consistently a kinetic model of the field-induced polarization reversal. It includes not only random nucleation events but also the subsequent elementary events of the lateral growth obeying the Merz law exp(-E_l/E ) with the field E_l = E_n/3√3 controlled by the crystal symmetry. Numerical simulations show distinct stages of the domain nucleation, lateral growth, and coalescence. In accordance with experiment, the polarization switching time obeys the law exp( E_*/E ) with E_* = (E_n + 2E_l)/3, while the hysteresis loops show a standard behavior with the coercive field E_c = (3-5) kV/mm weakly dependent on the field ramping period.

Fluorescence spectroscopy, which employs excitation wavelength scanning, is a powerful tool for chemical, biological, and medical diagnostics. It allows one to characterize the distribution of fluorophores in samples of various nature. However, when the fluorophores are initially unknown, interpreting large sets of excitation wavelength-dependent fluorescence spectra can be challenging, especially when there are data losses in the measured excitation-emission matrices due to random causes or systematic factors. In this paper, we propose to restore the damaged areas of the spectrum using the principal component analysis. This can be achieved without data loss because individual fluorophores’ fluorescence spectra are independent of the excitation radiation wavelength.

The present paper describes the Monte Carlo simulation of the silicon nanowire growth by the vapor-liquid-solid mechanism using gold droplets as a catalyst. The growth of tilted nanowires on Si surfaces with (111), (011) and (100) orientations is considered. It is found that the silicon nanowire orientation and morphology is affected by the size of gold droplets. The growth of tilted nanowires in the ⟨011⟩ and ⟨211⟩ directions using small-size droplets is demonstrated. As the droplet size increases, ⟨111⟩ becomes the most probable direction of nanowire growth. Diagrams demonstrating the influence of the gold droplet size on the probability of the nanowire growth direction on Si surfaces are presented. The kinetics of unstable growth of silicon nanowires catalyzed by small-size droplets is analyzed.

A method has been developed for modeling the transmission of channel signals of the M-QAM modulation format using the CO-OFDM (Coherent Orthogonal Frequency Division Multiplexing) technology over a fiber-optic path operating in a nonlinear regime. Using the normalized analytical expressions obtained, signal distortions on the receiving side are modeled for given parameters of the transmission system, and the signal quality factor (Q-factor) is calculated based on a statistical analysis of the signal and noise parameters. The model helps to clearly represent the signal distortion in the constellation of signal points in the IQ-diagram for given parameters of the transmission system. The paper presents a model of a transmission system for an OFDM signal with a total rate of 4 Tbit/s using a standard single-mode optical fiber over distances of 80, 160, and 240 km. To achieve the maximum signal quality factor at such transmission distances, optimal levels of optical signal power of +5.5, +4, and +2.5 dBm have been found.

Image quality assessment is crucial in the design of optical systems with an increased depth of the field and containing axicons, which possess two caustics, retain the linearity property but are spatially variant, creating difficulties for their analysis. We propose to consider the images formed by each of the caustics within the framework of the linear systems theory. A theoretical analysis of image formation is performed and PSFs are found for three optical systems in which toroidal light waves are formed by means of the axicon, as well as multiple experiments are carried out to determine the resolving power of such systems. As a result, it is shown that the axicon produces an image of a single object as a continuous set of ‘intermediate’ images along the focal segment. Light beams incident from the object to the centre of the axicon produce an image in the immediate vicinity of the axicon, while beams incident to the periphery of the axicon produce an image at the periphery of the focal segment. In doing so, all these low-contrast images mask each other. The lens-axicon tandem simultaneously produces images of the object both at the near diffraction zone in the form of a set of ‘intermediate’ images and at the far zone in a geometrically transformed form. Moreover, in the near diffraction zone, the depth of the field imaged by the tandem can exceed the depth of the field imaged by the single objective. The experimental data confirm the theoretical conclusions.

The paper presents the study of the transmission loss dependence in the 1.5-1.6 μm range for tapers, depending on their length, melting speed, and constriction dimensions using the Corning SMF-28 optical fiber as an example. The tapers are fabricated on the Fujikura FSM-100P, 100P+, LZM-100 welding machines and Lightel CW-200B coupler workstation. As a result of the experiments, a taper configuration with the minimum losses of -0.5 dB is determined. Using the Lightel CW-200B station, it is possible to manufacture a mode adapter for matching the modes of a standard polarization-maintaining optical fiber Fujikura SM15-PS-U25D and a highly nonlinear fiber with a reduced core HNLF PM. Due to better matching of the mode fields, the connection losses of these optical fibers are reduced from -3 to -1.25 dB.

The approach of applying machine learning methods to automatically detect people in forest-steppe areas in images is investigated. The artificial neural network technology is used to detect people from photographs. Deep learning methods of convolutional neural networks (YOLOv51, DenseNet, CenterNet, InceptionV3, Xception, and Faster R-CNN) are used in interaction with the "transfer learning" technique. Based on YOLOv51, a neural network is trained, which makes it possible to identify people using graphical images with an accuracy of 0.8795 on a test sample using the F1-score metric with a threshold value of 0.5.

Currently, many studies are aimed at increasing the information capacity of data transmission channels by using the orbital angular momentum (OAM) of laser beams to encode information. The use of this approach in atmospheric optical communication systems is limited by the distorting effect of atmospheric turbulence, which makes decoding difficult and reduces the data transfer rate. In addition, the intensity distributions of vortex beams with opposite in sign OAM values are identical in the case of homogeneous media, which limits the use of the OAM sign for encoding information. The main goal of the study was to evaluate the fundamental possibility of using neural networks to recognize opposite in sign OAM values of vortex beams in a turbulent atmosphere only through intensity images. The study is based on numerical simulation of the Laguerre-Gauss beam propagation in a turbulent atmosphere and further use of the obtained intensity images for training and testing neural networks. It has been shown for the first time that the use of neural networks makes it possible to recognize opposite in sign OAM values of Laguerre-Gauss beam through intensity images in case of propagation in a turbulent atmosphere with an accuracy of more than 90%. The obtained results can be useful for developers and researchers of atmospheric optical communication systems using OAM of vortex beam.

To form plasma antennas in various radio and telecommunication devices it is necessary to increase the relaxation time of laser breakdown centers. To overcome this problem, the processes occurring in aerodisperse media containing solid microparticles during interaction with laser radiation are considered. The decay times of plasma with aerosol particles under the influence of nanosecond and microsecond laser pulse have been analyzed. The influence of the electron shell around solid microparticles on the creation of a continuous ionization zone in the aerosol atmosphere formed by overlapping plasma halos around microparticles has been evaluated. The conditions necessary for the creation of a long ionized channel formed by breakdown centers during explosive evaporation of atmospheric microparticles in the zone of influence of a nanosecond pulse of a CO₂ laser and further maintenance of the formed plasma by the radiation of a microsecond laser are considered. A scheme of an experimental setup for creating a long ionized channel in an aerosol atmosphere is suggested. The results can be used for creation of wireless communication channels in the atmosphere.

The sulfur dioxide (SO₂) plays a key role in the winter-spring stratosphere of the Arctic because the sulfur compounds SO₂ and H₂SO₄ (together with nitric acid HNO₃) are the primary construction materials going to form the polar stratospheric clouds (PSCs). This paper studies the maximal SO₂ concentrations and total SO₂ columns at four Arctic sites: Eureka (Canada), Ny-Ålesund (Norway), Thule (Greenland), and Resolute (Canada) based on data on the minimal temperature, maximal negative deviations of ozone concentration from multiyear average, maximal sulfur dioxide concentration in the Arctic stratosphere, and the total ozone and sulfur dioxide columns calculated from the corresponding altitude profiles. The temperature and ozone mixing ratio profiles are obtained from the Aura MLS observations for 2005-2022; the sulfur dioxide mixing ratio profiles are calculated from Aura MLS observations for 2010/11, 2019/20, 2020/21, and 2021/22. The results can be useful for studying of how SO₂ affects the PSC formation and O₃ destruction in the winter-spring stratosphere of the Arctic.

The article is devoted to experimental study of hyperspectral method of detection of oil pollution on the earth surface in the near-IR range. The results of experimental measurements of spectral brightness coefficient of soil samples contaminated with various types of petroleum products in the spectral range 1.6-2.5 mm are given. The influence of soil moisture and rainfall on the spectra of reflection of soils (various types of sand and soil from forest and park areas) contaminated with petroleum products (Moscow and Samara oil processing plants, kerosene, gas condensate, various gasoline brands, motor oils, and diesel fuel) was studied. It was shown that spectral notches of about 1.73 and 2.3 mm (typical for soils contaminated with oil products) in most cases remain in the spectra of reflection under conditions of moderately wet soil, moderate “rain”, and even heavy “rain”. The results of the work of the created neural network show the probability of detecting oil pollution on the earth surface to be more than 99% under conditions of moderately moist soil and moderate “rain” and more than 88% under conditions of heavy “rain” and wet soil for 14 spectral channels with a resolution of 10 nm in the range 1.6-2.4 mm.

The NH Earth polar stratospheric vortex significantly varies from year to year in winter, which periodically lead to the occurrence of sudden stratospheric warmings (SSWs). Such events significantly disturb the circulation and chemical composition of the polar stratosphere. Our understanding of the wave processes that are recorded in the stratosphere and are directly involved in the occurrence of SSWs remains incomplete to date. Oscillations of the polar stratosphere of the Northern Hemisphere in the period from 1979 to 2023 are studied based on ERA5 reanalysis data. The method of current spectra is used to study the variability of the periodicity of wave processes in the polar stratosphere for different time intervals. As the main indicator of the wave properties of the stratosphere, we use the field of the vertical component of the wind speed in the region between 60 and 90° N. It is shown that in some years, oscillations of the stratosphere coincide with or are close to the periods of the main waves of the fortnightly and monthly lunar gravitational tide. The causes and consequences of the oscillatory processes synchronization in the polar stratosphere with the lunar gravitational tide are discussed. The results can be useful for improving the understanding of the mechanisms of occurrence of SSWs, as well as for improving the forecast of such events.

The paper evaluates the experience of creating a regional monitoring system for the turbulent energy exchange of the atmosphere with the underlying surface. An original technology for building an observation network based on ultrasonic automatic weather stations of domestic production has been developed. Based on the developed technology, the TomskFluxNet system has been deployed in Tomsk - the first urban network of observations of the characteristics of turbulent energy exchange of the atmosphere with the surface in Northern Eurasia with a pronounced continental climate. The first experimental results were obtained, on the basis of which significant differences in turbulent heat and momentum flows over urban and natural underlying surfaces were revealed. The results can be used to verify and improve the parameterization of the urban surface, which are actively developing in land-air models and weather forecast.

The phenomenon of increased burning velocity of a laminar fuel-rich ethanol flame with droplet injection was investigated numerically, and the results were compared with calculations for ethanol combustion without injection with the same mass fuel consumption. The calculations show that the presence of a dispersed phase in the form of 14 μm droplets with a mass flow rate of 0.5 g/min and a gas flow rate of 1.6 g/min significantly increases the flame propagation velocity compared to the combustion of gaseous ethanol with a flow rate of 2.1 g/min. The laminar flame speed increases from 23 cm/s in the combustion of only the gaseous fuel to 42 cm/s in the combustion with droplet injection. This effect correlates with a more than threefold increase in atomic hydrogen concentration in the flame and with a twofold increase in HCO concentration.

The dynamics of gas temperature was studied using as an example a single cylindrical channel with a diameter of 2 mm - a Raschig ring - placed in a porous medium made of such rings. The gas and thermocouple wire temperatures on the channel axis and the temperature distribution in the channel were calculated for two processes: the first is the pressure rise in a closed vessel during flame propagation in the space free of the porous medium, and the second is the cooling of the gas after the flame passage through the channel. For both processes, the gas temperature and the equilibrium temperature of the gas and the porous medium were measured using a thermocouple with a wire diameter of 15 μm in a cylindrical pore with a diameter of 2 mm. It was shown that during gas compression at a constant low rate, the thermocouple provided adequate measurements of steady-state gas temperature. However, when reaching the steady-state value, the larger the wire diameter, the longer was the thermocouple lag. During cooling of the instantaneously heated gas, the thermocouple measurements of gas temperature were found to be significantly underestimated. This is due to the higher heat capacity of the thermocouple wire as compared to the heat capacity of the gas in the pore. During the heating of the thermocouple, the gas cools down due to heat transfer into the pore walls.

Based on the large-eddy-simulation (LES) turbulence model, the shock wave propagation process in the roadway with branch structure was studied, focusing on the changes of overpressure under different explosion intensities and a different number of branches. Four conditions of gas accumulation length of 5, 10, 15, and 20 m are used in four models to reveal the influence of the branch structure. The results show that the shock attenuation coefficient of the main roadway no longer changes linearly with the gas accumulation length when there are branch structures in the roadway. When the gas accumulation length is constant, the increase of the number of branches can effectively reduce the rise rate of the impact overpressure value within a certain propagation distance. The overpressure in the branch roadway away from the explosion site is less affected. Due to the influence of multi-branch structure of adjacent roadway, its fluctuation is more chaotic than that of main roadway.

A closed mathematical model of continuous spin detonation of a synthesis gas---air mixture is formulated in a three-dimensional unsteady gas-dynamic formulation, and an algorithm for numerically solving the problem is developed. The model is verified using experimental data on ignition delay at high temperatures and the results of one-dimensional numerical calculations of the Chapman---Jouguet detonation parameters. For three stoichiometric compositions in an annular cylindrical combustor 306 mm in diameter, single-wave continuous spin detonation modes are obtained and the three-dimensional structure and the main flow parameters are analyzed. The minimum possible flow rates for continuous detonation are obtained in the case of variable specific mixture flow rates in a range of 90 ÷ 260 kg/(s · m²). The resulting data are compared with existing experimental data.

The methodology of calculating the problem of detonation initiation in acetylene-oxygen mixtures by a small-diameter sphere flying with a velocity greater than the Chapman-Jouguet detonation velocity is presented. A reduced kinetic scheme of chemical reactions is tested against experimental data on the ignition delay time, detonation propagation velocity, and detonation cell size. Regimes of oblique detonation and combustion in an acetylene-oxygen mixture diluted by argon are obtained in experiments in the pressure range from 21.1 to 60.7 kPa. The energy of detonation initiation by a high-velocity projectile is estimated, which demonstrates good agreement between analytical, numerical, and experimental data. Based on this estimate, the initiation of oblique detonation by a high-velocity projectile in an acetylene-oxygen mixture is calculated. A correlation between the numerically predicted flow regimes and analytical estimates is obtained.

Flows with multiheaded rotating detonation in a combustor in the form of an annular gap between plates are numerically studied. It is assumed that a homogeneous propane-air mixture enters the combustor from a reservoir with specified stagnation parameters through elementary nozzles uniformly filling the outer ring that limits it. The gas-dynamic parameters of this mixture are determined as functions of the stagnation parameters and static pressure in the gap. The study of multiheaded rotating detonation is carried out under the following conditions: the number of waves is 1, 2, 4, and 8, while the stagnation pressure slowly decreases over time according to a linear law. It is revealed that shock-wave structures can be qualitatively different, depending on the stagnation pressure, and that detonation ceases at a stagnation pressure lower than the critical pressure. The dependences of the power characteristics of the traction equipment on time are presented. Calculations are performed on the Lomonosov supercomputer at the Moscow State University using an original software package implementing a modified Godunov method and a one-step reaction kinetic model.

This paper presents generalized results of numerical analysis of the effect of mesoscopic thermal dissipation and heat transfer processes on the temperature field formed in a shock-compressed viscoplastic porous material containing spherical pores with a thin layer of plasticizer on the surface of pores in plastic flow. Based on the results, a theoretical estimate is made of the effect of the mechanical properties of the phases on the critical conditions of shock-wave initiation of chemical reaction in the two-phase porous energetic material.

The investigation of the energy output resulting from alterations in the aluminum powder content in emulsion explosives permits the expeditious transformation of civilian explosives into military explosives during wartime, while simultaneously enhancing the energy capacity of the equipment. One can choose the appropriate scenario based on the form and energy yield of the explosives. The experiments were conducted using emulsion explosives with 0%, 5%, 10%, 20%, 30% and 40% mass percentage of aluminum powder. The study investigates the effects of varying aluminum powder contents on detonation velocity, brisance, underwater explosions, and aerial explosions. The experimental outcomes show that the detonation speed decreases with increasing aluminum powder content. The brisance of the emulsion explosive initially ascends and subsequently descends, reaching its pinnacle value of 22.71 mm at an aluminum powder content of 20%, reflecting a surge of 19.97%. As the aluminum powder content increases, all underwater explosion parameters of the emulsion explosive increase linearly, with the total energy reaching its maximum at 40%, showing increases of 120% compared to the aluminum-free emulsion explosive. The highest pressure increase in aerial explosions is achieved at an aluminum powder content of 30%, reaching 113.28 kPa and signifying a 78% rise. The experimental findings demonstrate that in the context of underwater munitions employing high-energy emulsified explosives, including 40% aluminum powder results in the optimal level of destructive capability. Conversely, when considering applications for aerial weaponry, the maximum explosive potential is attained with an aluminum powder content of 30%.

A wide-range semiempirical equation of state of liquid and gaseous neon is constructed with account for evaporation and thermal ionization based on a modified van der Waals model for mixed substances. The model and the simplifications used in this study are described. The values of the key parameters are given. The results of model calculations are compared with experimental data up to a pressure of ≈1 000 GPa and with the results of calculations based on other models, including those at a pressure of >1 000 GPa. In the low-density limit, the model transforms into an equation of state of a mixture of ideal gases of atoms, ions of all multiplicities, and electrons with a concentration determined by the Saha equations.

Experiments on measuring the electrical resistance of copper foil under shock compression are analyzed for determining the basic parameters responsible for the concentration of shock-induced defects in the metal. Based on the excessive electrical conductivity of the metal, the concentration of point defects of the crystal structure in copper samples placed in various cartridges (Plexiglas, micarta, and fluoroplastic) is estimated. The cartridge material is found to affect the number of defects arising due to shock compression of the metal. The cartridge with a higher shock impedance corresponds to a smaller concentration of defects in the sample (at identical pressures of the shock wave in the cartridge). A physical model of generation of crystal structure defects due to shock compression is formulated to explain the experimental results obtained. According to this model, defects are formed during matter compression in the shock wave front and remain “frozen” after unloading. A new portion of defects is formed after secondary compression of matter, resulting in accumulation of defects. It is assumed that the parameter determining the number of defects arising under dynamic loading is the algebraic sum of metal deformations at each stage of shock compression. The data presented in the variables concentration of defects - deformation yield a dependence that mitigates the difference in the cartridge material. The analysis performed shows that the sum of deformations can be considered as a parameter determining the concentration of defects generated by shock compression of copper.

The expansion and rupture of metal casing under internal explosion loads may form a large number of fragments. An understanding of how the relevant parameters of metal casing influence the fragment mass distribution, is essential for the prediction of the power of metal casing explosive devices and the effective design of protection systems. In this paper, the important influence factors of metal casing (mechanical properties of casing material, geometric structure of casing, performance of explosive) were determined by a dimensional analysis. Several complete recycle tests of fragment were carried out to analyze the influence of these relevant parameters on the natural fragment mass distribution. Based on the test results, it is found that these relevant parameters have a linear relationship with the distribution modulus of the fractal model of natural fragment mass distribution in double-logarithmic coordinates. A formula was developed to predict the distribution modulus, whose influence parameters were considered in a dimensionless way. The applicability of the estimating method was verified with the test data of a casing with irregular axial geometry. The error between the calculation result and test result was only 6.9%. In addition, the test data compared with the prediction results of two theories, and the fractal model of natural fragment mass distribution showed better accuracy. This work can provide a reference for the hazard assessment and protection system design of metal casing explosive devices.

The dependence of vegetation indices NDVI (Normalized Difference Vegetation Index) and EVI (Enhanced Vegetation Index) on the content of pigments in plants was studied at three sites with environmental disturbance: at the territory of diesel fuel spill, in the region of natural oil occurrence, and at a post-fire site. The studies have shown that the stability of plant species against pollution with petroleum products increases in the sequence: sedge < cereals < field horsetail < willow < moss. Determination of interrelation between remotely measured optical characteristics of the vegetation cover and the concentrations of pigments revealed a direct dependence of NDVI and EVI values on the concentrations of pigments in field horsetail and cereals, and inverse dependence for willow, moss, and sedge. In the region of natural oil occurrence under the conditions of pollution with oil, a substantial decrease in total chlorophyll content is observed for wild strawberry, artemisia, and thyme in comparison with the reference conditions. A decreased content of chlorophylls and carotenoids was detected at the post-fire site in padus, and an increased pigment content in dwarf elder, which provides evidence of the higher stability of dwarf elder to the action of high temperatures. The vegetation indices at the post-fire site are substantially lower than at the background (intact) site.

Analysis of the properties of the Bazhenov Formation metalliferous oil from the West Siberian oil and gas basin is presented During the development of these oil reserves, there is a danger of heavy metals (for example, vanadium and nickel) entering the environment during oil extraction, transportation and refining. The information from the database of the Institute of Petroleum Chemistry SB RAS (Tomsk) and the methods of statistical and spatial analysis of geographical information systems are used in the work. Based on the classification of hard-to-recover oil, deposits of the Bazhenov Formation with high and medium vanadium and nickel content have been identified. The distribution of oil from these fields over the depth of occurrence is shown. With an increase in the depth of occurrence, the concentration of metals in oil decreases by almost an order of magnitude. The lithological features of reservoir rocks have been revealed: metalliferous Bazhenov oil is mainly found in sandstones (86.2 % of oil samples) and in sandy-siltstone rocks (13.8 % of samples), which confirms that the reservoirs of the formation belong to the terrigenous type. The average values of reservoir parameters characterising filtration properties and the capacity of deposits are determined. To analyse metalliferous Bazhenov oil, a set of 68 oil samples from 33 fields in the West Siberian oil and gas basin was used. The results obtained in the study can be used in the development of new methods and technologies, and improvement of the existing ones, for the extraction and processing of metalliferous oil, taking into account environmental consequences.

Oil production from low-permeable reservoirs is an urgent and promising issue because of the depleted reserves of oil extracted using traditional procedures, both in Russia and abroad. The statistical analysis of porosity distribution in the sediments of the main oil and gas basins (OGB) of Russia is presented: the Volga-Ural, Timan-Pechora, North Caucasus and West Siberian. These basins have large reserves of hard-to-recover oil from complex formations with low porosity. Computer maps of the deposits with low-pressure reservoirs are presented. In the West Siberian basin, 15 deposits of this kind have been identified, 13 deposits in the Timan-Pechora basin, 63 in the North Caucasus, and the largest number of deposits is located in the Volga-Ural basin - 82. The great role of low-porosity rocks in the oil and gas potential of basins is shown, 80 % of the Russian reserves of low-porosity sediments are concentrated in the Volga-Ural basin. According to lithological characteristics, low-permeable reservoirs mainly belong to carbonate sediments, but the porosity of terrigenous rocks is higher, compared to carbonate deposits. The presence of reservoirs in various stratigraphic layers has been established, starting from the Cenozoic and ending with the Paleozoic, but most rocks belong to the Paleozoic age. The distribution of reservoirs with low porosity is analysed as the depths increase. It is shown that porosity decreases at great depths (over 5000 m) by a factor of 2-3, while the proportion of low-porosity sediments increases with depth, compared to medium-pored and highly porous rocks. In the future, at great depths, the role of low-permeable reservoirs as the sources of hard-to-recover oil will only increase.