Home – Home – Jornals – Thermophysics and Aeromechanics 2021 number 5

We present results of U-Pb (LA-ICP-MS) dating of detrital zircons from the alluvial deposits of the Angarakan River (North Muya Ridge, northern Baikal region), whose drainage basin is composed mainly of granitoids of the Barguzin Complex, typomorphic for the late Paleozoic Angara-Vitim batholith (AVB). Three age clusters with peaks at 728, 423, and 314 Ma have been identified in the studied population of detrital zircons. It is shown that small outliers of igneous and metamorphic rocks, probably similar to the large AVB roof pendants mapped beyond the drainage basin, are the source of Neoproterozoic and early Paleozoic zircons. The late Paleozoic cluster comprises two close peaks at 314 and 285 Ma, which totally «overlap» with the time of the AVB formation and mark a granitoid source of the zircons. The results of detrital geochronology, together with the data on bedrocks, point to the prolonged (~40 Myr) formation of the AVB, but the intensity of magmatism during this period calls for additional study. Based on the analysis of published geological, geochemical, and geochronological data, we assume that the AVB resulted from the plume-lithosphere interaction that began in the compression setting and gave way to extension 305-300 Ma (the Carboniferous-Permian boundary), which caused replacement of «crustal» granitoids by granitoids formed from a mixed mantle-crustal source.

Based on the materials collected by L.N. Repina in the southern Hövsgöl area (Mongolia) in 1986-1988, we describe three sections and identify lower Cambrian trilobites. The sections of Mt. Hurtel Harna and along the Ujigin Gol River were studied earlier. We consider trilobites that have been found in these sections for the first time: Redlihia zharkovi , Lermontoviella shanganica , Erbia granulosa , Kootenia siberica , and Parapoulsenia lata . The section along the ravine of the Zuun-Shuvuutyn-Sair Brook and the findings of trilobites in it are described for the first time. The found new trilobites make it possible to correlate the coeval lower Cambrian strata in the southern Hövsgöl area, Altai-Sayan folded area, and western Siberian Platform and refine the age of the certain parts of the Egyin Gol, Ukhaa Tolgoi, and Ujigin Gol formations.

The Quaternary stratigraphy of the southern West Siberian Plain is considered in the context of the updated International Chronostratigraphic Scale, with the Neogene/Quarternary boundary at 2.588 Ma. New geological, lithological, paleontological, and paleomagnetic data from a reference Quaternary section in the Irtysh River valley near Isakovka Village provide more rigorous constraints on the Lower-Middle Pleistocene stratigraphy and the respective deposition conditions. The Isakovka outcrop exposes two stratigraphically expressed and paleontologically characterized units that were deposited during regional Pleistocene interglacial events of different ages: the Strunino and Serebryanoe alluvium beds lying over eroded surfaces. The species of the Corbicula genus coexisting with numerous species of Palearctic molluscs, small mammals Allophaiomys deucalion, Mimomys reidi , and last rooted lagurids Borsodia found in the Strunino alluvium are known also from continental equivalents of the warm upper Gelasian Stage in different parts of northern Eurasia. Judging by the presence of extant corbicules, the Strunino alluvium was deposited in a warm climate, with a mean annual air temperature above +16 °C and a mean winter temperature no colder than -8 °C, in rivers that remained free from ice all year round. On the basis of fauna constraints for the Serebryanoe alluvium, along with the first appearance of the European Pisidium clessini molluscs in West Siberia, the unit can be correlated with one of the earliest Middle Pleistocene interglacial events. The faunal assemblages and spore-pollen patterns of the two units indicate that the climate during the Serebryanoe deposition was slightly cooler and wetter than during the Strunino deposition, though steppe landscapes predominated on watersheds in both events. The two alluvial beds, which are traceable in river bluffs, at 30 m above the modern water level in a tectonically stable part of West Siberia, mark the hypsometrically higher position of the river network during the Early Pleistocene and early Middle Pleistocene interglacials.

Using image recognition methods (principal component method (PCM) and discriminant analysis) made it possible to group and identify more than 500 research objects developed in five oil and gas areas of the West Siberian oil and gas province (WSOGP), which are confined to 13 large tectonic structures and 10 productive horizons. The grouping was made according to 19 parameters characterizing the mode of oil and gas occurrence and the geophysical and physicochemical properties of the reservoirs and hosted fluids exerting a prevailing influence on the recovery of oil reserves and used on projecting the development of research objects. The performed study has identified 19 relatively homogeneous groups of objects, each having a specific set of geophysical properties. It is shown that the parameters reflecting the geophysical and physicochemical properties of the reservoirs and fluids within the identified groups of objects exert different effects on the recovery of oil reserves. This requires differentiation and grouping of the objects during the solution of various development problems. It has been established that the specific features of groups of objects are determined primarily by areal, tectonic, and stratigraphic factors and that grouping must be performed separately in each stratigraphic system. Algorithms are proposed for grouping the developed oil and gas fields and for searching for groups of analogous objects in fields out of exploration that are most similar to the developed ones. The performed grouping and the results obtained provide the necessary information about the research objects and increase its reliability, thus making possible to improve the efficiency of managing the oil company assets, i.e., the WSOGP oil fields.

We present results of an integrated research into the spatial distribution of methane in the area of the northern closure of the Central Basin of the Sea of Japan and in the southern part of the Tatar Trough. Methane emissions have been revealed in the study area. The methane fluxes are distributed unevenly within the area (1 to 23 mol/(km² day)). The discrete high-frequency measurements and calculation of methane fluxes at the water-atmosphere interface, combined with the study of the content of natural gases and microbiologic parameters in sediment cores, allow us to explain the formation of local methane emission zones in the water area. Despite the great sea depths, there are sources and fluid-conducting zones that determine methane concentrations (exceeding the equilibrium ones) and high methane emissions from the water area. The data obtained provide new information and suggest the presence of deep gas sources, which determine gas dispersion in the bottom sediments, the methane content in the surface water layer, and the distribution of methane flows at the water-atmosphere interface in the study area. This study is part of the integrated program of geological and geophysical expeditionary research performed by V.I. Il’ichev Pacific Oceanological Institute (Vladivostok) in the northern part of the Sea of Japan.

Results of study of natural waters of the Baidar valley (southwestern Crimean Peninsula) obtained during the 2018-2019 field works are presented. Major groundwater resources of the study area are confined to the Upper Jurassic aquifer complex, which serves as a recharge source for the aquifer systems of the Plain Crimean and the Azov-Kuban’ artesian basins and hydrogeologic folded region of the Crimean Mountains mega-anticlinorium. The regional waters are fresh and ultrafresh, predominantly of calcium bicarbonate composition, with TDS varying from 208 to 1269 mg/dm³. The study enabled their classification into eight geochemical groups: (1) waters of a regional fracture zone in carbonate-terrigenous rocks affected by continental salinization; (2) waters of a regional fracture zone affected by leaching of aluminosilicates and sulfide oxidation; (3) waters of a regional fracture zone dominated by sodium aluminosilicates in the fracture filling (long-term interaction in the water-rock system), affected by continental salinization; (4) regional fracture zones dominated by sodium aluminosilicates affected by anthropogenic continental salinization; (5) groundwaters in fracture-vein aquifers affected by leaching of aluminosilicates and sulfide oxidation; (6) fracture-vein aquifers affected by leaching of sodium aluminosilicates (long-term interaction in the water-rock system); (7) waters in fractured karst aquifers; and (8) surface waters subjected to continental salinization. Fracture karst waters, which were found to be most protected against human impact and continental salinization processes, are slightly alkaline (pH = 7.7), fresh (with average TDS = 444 mg/dm³), with low silicon concentrations (2.23 mg/dm³), and of calcium bicarbonate composition. Waters residing in regional fracture and fracture-vein zones are affected by continental salinization and anthropogenic load and are neutral to alkaline (pH = 7.1-8.6), predominantly fresh (TDS = 269-1269 mg/dm³), with average silicon concentrations of 4.61-4.70 mg/dm³, of calcium bicarbonate composition, with high concentrations of sulfate ion, magnesium, and sodium. The waters of the Chernaya River, Chernorechensk reservoir, and lakes, which are also affected by continental salinization, are slightly alkaline (pH = 8.3), brackish (TDS = 207-364 mg/dm³), with an average silicon concentration of 1.18 mg/dm³, of calcium bicarbonate composition, with high concentrations of chlorine ion, magnesium, and sodium. The calculated intensity of chemical-element migration in waters of the background composition follows the descending order: very strong, I_17.7 > Br_14.4; strong, Se_2.83 > B_2.22 > Sr_1.46 > Sb_1.12 > Be_1.07 > Hg_1.06; moderately strong, Zn_0.74 > Mo_0.50 > Li_0.46 > Sc_0.41 > Ag_0.18 > As_0.16 > Si_0.123 > Ba_0.122; weak, Cr_0.10 > Cu_0.096 > Bi_0.080 > Sn_0.068 > Tl_0.067 > P_0.062 > Ni_0.043 > Ta_0.040 > Ge_0.034 > Cd_0.028 > Fe_0.026 > Rb_0.024 > >Co_0.023 > Pb_0.020 > W_0.017 > V_0.012; very weak (inert), Nb_0.008 > Hf_0.0033 > Mn_0.0031 > La_0.0029 > Cs_0.0022 > Ti_0.0018 > >Ga_0.0016 > Y_0.0013 > Al_0.0008 > Zr_0.0008. All the studied waters are found to be of atmospheric origin and located along the global (GMWL) and local (LMWL) meteoric water lines. Their δ¹⁸O value varies from -9.9 to -3.3‰, and δD value, from -64.2 to -32.5‰. Sedimentary carbonate rocks, atmospheric carbon dioxide, organic compounds, and hydrolysis of aluminosilicate minerals serve as the source of δ¹³C bicarbonate ion in natural waters of the Baidar valley. Surface waters have a heavier carbon isotope composition (δ¹³C = -9.2 to -6.2‰), which is due to atmospheric CO₂, plant growth, and associated microbial activity. Fracture karst waters are characterized by a lighter carbon isotope composition (δ¹³C = -12.8 to -11.0‰) because of their interaction with dispersed organic matter. Waters of the regional fracture and fracture-vein zones display the widest variation in δ¹³C (-15.5 to -6.9‰), which is associated with a mixed type of «isotope supply» to the waters. A complex hydrogeochemical field that has formed in the Baidar valley tends to be increasingly affected by the anthropogenic factor.

We consider results of measurements of thermal conductivity, porosity, and permeability for 780 samples of Mesozoic sandstones and siltstones from the cores of 50 wells drilled in three southern regions of the West Siberian Plate (Novosibirsk and Tomsk regions, Surgut region of the Khanty-Mansi Autonomous Area). The thermal conductivity of the samples was measured twice: in dry and in water-saturated states. It has been established that the thermal conductivity of water-saturated rocks is on average 20-40 % higher. The thermal conductivities of dry and water-saturated samples show stable correlations between each other and with the sample porosity and permeability. These correlations can be used for the approximate estimation of the thermal conductivity of water-saturated rocks from the measured thermal conductivity of dry samples or even from the porosity values. The relationship between thermal conductivity and porosity can be used for the rapid assessment of rock porosity from the measured thermal conductivity of the core.

A mathematical model of the influence of the Earth’s magnetic field (the Hall effect) on results of the controlled source transient electromagnetic (TEM) method has been elaborated. For identification of this effect, we propose a schematic layout of the experimental grounded system with a pulsed loop source and signals recording by radial receive lines equally spaced relative to the loop. The 2018-2019 special field experiments were conducted in the Tatar region of the West Siberian Lowland with an aim to estimate the Hall effect contributions to the TEM method. To detect the Hall effect, transient electromagnetic responses were measured mainly by four receive lines radiating from a 500×500 m square loop. Analysis of the TEM results processing aimed at improving the signal quality and reducing the interference revealed a great similarity in signals from the radial lines, which is theoretically possible only under the Hall effect. Comparison of the field signals with the theoretical ones enabled estimation of the components caused by the Hall effect, in particular, conductivity at ~0.002 S/m.

Inductively induced electric polarization (IIP) is one of the aftereffects inherent in the geologic materials and affecting results of the transient electromagnetic method. Its effect on the inductive transient response manifests itself as a nonmonotonic EMF decay, including the polarity reversal. The dependence of IIP on many conditions makes it difficult to study the basic regularities in its manifestation. One of the ways to address this problem is to present the simulation results as a normalized transient response. From the most general point of view, the intensity and time range of the IIP manifestation are controlled by the competition between induction and induced polarization phenomena. Induced polarization manifests itself differently, depending on the transmitter used for the excitation of the ground response. Therefore, when studying polarizable ground, the results of the conventional IP method and those of the TEM method do not always correlate.

The influence of the interferometer optical system characteristics on the distribution of spectral power density of partially coherent light passing through the system is investigated. The results of effective wavelength measurements for partially coherent light sources are presented. It is shown that the optical system transforms the spectra, which leads to a systematic error of interference measurements using the scattered light phase. With atomically smooth surfaces used as a reference mirror, the influence of this system on the phase distortion is investigated. The systematic error is found to be approximately 5 nm in terms of height owing to phase distortion. It is shown that the use of atomically smooth surfaces as a perfect measurement surface allows this error to be significantly reduced down to 0.12 nm. The results of measuring an echelon of atomic steps with a countable number of monoatomic layers on the silicon crystal surface are reported. The interatomic (interplane) distance in the crystal lattice of Si with orientation [111] is experimentally measured for the first time by low-coherence optical interferometry, and its value is found to be 3.145 0.003Å.

The unique variability of modern fiber and integrated optics and also the development of physics of complex nonlinear optical phenomena and nanophotonics have contributed to the development of qualitatively new approaches to the implementation and control of pulsed lasing in fiber lasers in the last decade. In this paper, we present a structured review and comparative analysis of current methods for static and dynamic control of the regimes and parameters of generation in mode-locked fiber lasers.

Modified holographic photopolymer materials developed at NIOCH SB RAS, which, as a result of post-processing, provide high diffraction efficiency with a small thickness of the recording layer, have been studied by the method of recording reflection and transmission volume elementary holograms. Samples of volume reflection holograms with a diffraction efficiency of about 90% are obtained with a recording layer thickness of about 6 μm and refractive index modulation ∆n of no less than 0.036. The obtained holograms have high transparency in the entire visible range of the spectrum, low shrinkage, and good uniformity of the spatial structure of the grating, as evidenced by a clear picture of the side lobes of the spectral response contour.

The method and the possibility of realizing isotropic Bessel-Hilbert diagnostics of the phase optical density fields of gaseous, condensed, and reacting media are discussed. The probing field in such systems is formed as a mono- or polychromatic configuration of the Bessel beams. The spatial-frequency Fourier spectrum of the Bessel beams is optically coupled with the concentric phase structure of the isotropic Hilbert filter, and the color structure corresponds to the spectral sensitivity of the photomatrix of a video camera connected to a computer, which analyzes the frame-by-frame sequence of the resulting images. The structure of such a probing field is resistant to diffraction disturbances induced by the medium under study and their influence on the isotropy of the Hilbert visualization of the phase optical density. The area of possible applications is experimental hydro and gas dynamics, thermal physics, oceanology, as well as the corresponding industrial technologies.

It is shown that the use of an ensemble of reading heads of a certain format, consistent with the parameters of the measuring raster and the matrix of indicator rasters in readheads, can significantly reduce the distorting effect of the systematic component of the instrumental error of the raster. It is noted that the specific technical solution considered in the present paper for matching the parameters of complementary lattice filters is not the only one for the raster used.

The results of experiments aimed at studying the concentration dependences and the time and temperature stability of the quadratic response of guest-host type materials based on polycarbonate and original synthesized dyes are presented. It is shown that modifications of the chromophore by dendronic side substituents significantly improve the solubility, which allows construction of polymer materials with a high content of optically active particles. The materials have high time and temperature stability and exhibit d₃₃ up to 80 pm/V at a chromophore concentration of 2.5^.10²⁰ cm^-3.

The main approaches to identifying the contours of objects in hyperspectral images are considered. Algorithms for extracting the contours of spectrally selective objects based on the spatial spectral correlation and interspectral difference of gradients are presented. The efficiency of the proposed algorithms for processing real hyperspectral images under the condition of additive Gaussian noise is demonstrated.

The paper is devoted to solving the problem of constructing a state estimation of a finite discrete-time Markov chain. A Markov chain is considered as a linear dynamic system with incomplete state information. The state estimation is based on the Luenberger observer. The conditions for state estimation invariance to perturbations of transition probabilities in a Markov chain are obtained. A numerical example is considered.

The article proposes a method for selecting stable feature points of images obtained using the BRISK and AKAZE algorithms. The method is based on the selection of points that remain in the image after its significant transformation. The results of numerical experiments, based on 1000 images, confirming the effectiveness of the proposed method are presented. It is found that the sets of points obtained using the proposed method contain three to five times more stable points than random sets of the same size. It is shown that, for the selection of stable points, it is more efficient to use significant transformations of images.

The properties of the method for testing the hypothesis of theindependence of random variables based on the use of a nonparametric pattern recognition algorithm corresponding to the maximum likelihood criterion are investigated. The distribution laws in the classes are estimated on the basis of the initial statistical data, assuming the independence and dependence of the compared random variables. Under these conditions, the estimates of the probability of an error in pattern recognition in classes are calculated. Based on their minimum value, a decision is made on the independence or dependence of random variables. The application of the proposed technique allows us to circumvent the problem of decomposition of the range of values of random variables into multidimensional intervals. The effectiveness of the proposed technique with the complication of the relationship between random variables and changes in the volume of the initial statistical data is investigated by the method of computational experiments.

On the basis of the previously developed mathematical model and algorithms for functioning of the mirror system control system of the Millimetron Observatory, the results of numerical simulation of obtaining permissible values of the errors of the on-board 3D scanner during the preliminary measurement of the geometric parameters of the spatial location of the mirror system of the Millimetron Observatory using optical control marks on the surface of the mirror system are presented. When modeling the measurement of the geometric parameters of the spatial arrangement of the control marks, two options for their execution on the panels of the main mirror of the telescope are considered: Option 1 - the control marks are given in the form of mirror spheres with a diameter of 10 mm, located at the four corners of the panels of the main mirror; Option 2 - the control labels of Option 1 are complemented with miniature swivel mirrors. The miniature mirrors allow the measuring beam to be rotated so that through the mirror it is possible to measure the geometric parameters of the control marks located on adjacent (for mirrors) panels of the main mirror. It is revealed that, when the permissible values of errors in the operation of the 3D scanner are reached (9 μm for the rangefinder channel and 2 angular sec for the angle channels) and combined control marks are used (option 2), it is potentially possible to build a device for pre-tuning the mirror system.

The article presents the structure and implementation of a digital model of a coalmine face. The digital model contains the parameters of the coal seam, the technical parameters of the mining machines, and economic indicators. The digital model can be used to support decision-making to increase the productivity of the coalmine face and to assess the effect of using new mining machines or new technology. An example of using the digital model to determine the dependence the financial indicators of functioning of the face on the face length and technological schemes of coal mining is given.

The article is devoted to the development of a numerical algorithm for determining the optimal regime parameters of a chemical process. The statement of the problem of multi-purpose optimization of the chemical process conditions is formulated in the general form. To solve this problem, a genetic algorithm is presented. The algorithm is based on the FFGA method, which allows one to determine many Pareto-optimal solutions. A computational experiment is carried out for the thiol aminomethylation reaction in order to determine the optimum temperature and reaction time, ensuring the maximum conversion of the starting materials and the maximum selectivity of the formation of the target reaction product.

The paper suggests an approach to the construction of equipment for diagnostics of dangerous states caused by destruction of bearing elements in propulsion systems like gas-turbine engines. The approach is based on continuous monitoring of external factors affecting the bearing assembly and of the presence of metal particles in the engine lubrication system, which are carried out using original single-coil eddy-current sensors, modeling of the wear of bearings, and expert verification of the remaining resources in changing operating conditions. This makes it possible to determine the residual life of the bearing assembly and predict the time until its intensive destruction. Thus, the possibility of taking measures to prevent the development of emergency situations is provided.

In the present paper, the results of a study of the influence of textile materials on the structure of the aerodynamic wake behind blunt-body models in the form of quasi-two-dimensional and cantilever cylinders are reported. The fabrics used were previously examined in the works by co-authors while determining the drag coefficient of a two-dimensional cylinder. The change in diameter in the latter case proved to be not more than 1%, and it was considered insignificant. The use of fabrics has made it possible to reduce the critical Reynolds number to about 2·10⁵. The two- and three-dimensional flows turned out to be similar in terms of fluctuation level, whereas some narrowing of the wake behind the cantilever cylinder occurred due to the three-dimensional structure of the flow. Based on the results of spectral analysis, complete similarity between three- and two-dimensional flows was demonstrated, both for the flow around a smooth cylinder and for the flows around cylinders fitted with textile materials.

Methodological aspects of stagnation-temperature measurement in high-enthalpy supersonic air flows using a thermoelectric transducer (thermocouple) with shielded measuring junction are analyzed. Specific features of thermo- and gas-dynamic processes under the conditions of interest, leading to a substantial deviation of temperatures measured using traditional measuring methods from the true temperatures, are demonstrated. Refinements to the method of determining the temperature of high-enthalpy supersonic air flows allowing one to reduce the deviation from the true temperature are introduced. A mathematical apparatus developed for analysis of experimental data and for quantitative estimation of temperature-measurement error is described. Approbation of the proposed approaches and validation of the developed mathematical models are performed using the results of experimental studies of high-enthalpy supersonic flows. A satisfactory agreement between the results of indirect temperature measurements and specified temperature values is shown. The results of the study can prove useful in the development of techniques and methods, and in the analysis of physical experiments with high-enthalpy flows.

Nano-tracer Planar Laser Scattering (NPLS) technique and pseudo-color processing technology are employed to investigate the flow field after a thickness plate of non-isobaric initial conditions. The results show that the supersonic mixing layer behind the blunt trailing edge will deflect toward the low pressure side which is consistent with the canonical mixing layer. However, there is no laminar region for any unmatched cases and the turbulent state of the mixing layer seems to be restricted for the case of the low-speed side with a higher pressure.

A physical-mathematical model of a plane supersonic boundary layer of a vibrationally excited dissociating gas in the Prandtl approximation is presented. The simplest case of a diatomic gas parameterized according to the data for nitrogen is considered. A number of simplified formulas for calculating the transport coefficients and the dissociation and recombination rates for a molecular-atomic mixture, which are admissible for typical conditions of supersonic and hypersonic boundary layers, are substantiated. Comparative calculations of numerical and locally self-similar solutions of the boundary layer equations on a flat plate for typical conditions of a high-enthalpy wind tunnel and hypersonic flight in the upper atmosphere are performed. It is shown that the atomic concentration profiles calculated on the basis of these approaches differ significantly. In this regard, in order to adequately take into account the effect of chemical reactions in the boundary layer stability calculations, it is necessary to use the profiles of hydrodynamic parameters calculated numerically on the basis of full boundary layer equations. Locally self-similar solutions can serve as initial conditions for numerical calculations.

Film cooling efficiency averaged over the length of a one-row ring of holes for the case of a flat surface with air blowing through fan-shaped holes was estimated experimentally and normalized by the respective efficiency for cylindrical holes in a wide range of injection parameters m (from 0.25 to 5.5) and blowing angles a (from 30° to 75°). Ranges of regime and geometric parameters of film cooling systems in which fan-shaped holes provide a higher cooling efficiency in comparison with cylindrical holes have been identified. With the case of α = 30° taken as an example, we show that very high injection parameters ( m = 4.5¸5.5) in the entrance region of the mixing zone ( x / d < 10) make the relative efficiency decrease from 1.7 to 1.05 with the increase of x / d . Simultaneously, the relative efficiency increases from 1.05 to 1.6 in the main mixing zone ( x / d > 10). Fan-shaped holes provide a higher film cooling efficiency at optimal and high values of m and α = 45° (under all other conditions being identical) in comparison with cylindrical holes both in the entrance region and in the main mixing zone. At α = 75°, the efficiency is higher than throughout the whole examined range of injection parameters and throughout the whole examined range of the normalized distance from the location of the injection place. The relative efficiency decreases from 4 to 1.5 in streamwise direction in the entrance region of the mixing zone ( x/d < 5), and it ranges between 1.5 and 2.5 in the main mixing zone ( x/d > 5) at all values of injection parameter considered in the paper.

Oscillations of a cantilevered rod - fuel element simulator - were experimentally studied in an annular channel with a longitudinal ascending fluid flow using an original sensor built on the basis of the electrical impedance method. The data on the trajectories of the rod axis movement and changes in amplitude and frequency of rod vibrations depending on the velocity of the axial fluid flow are given. The data on rod vibration obtained using the electrical impedance method and high-speed video recording are compared.

A model of a rivulet formed on the coils of a tubular heat exchanger has been developed. The cross-sectional shape of the rivulet is determined taking into account the forces of gravity of liquid, the forces of surface tension, and centrifugal forces. The equations for the coordinates of the free boundary points of the rivulet are presented in the integral form based on the analytical solution of the problem. The cross-sectional areas of rivulet and liquid bridge are compared, as well as the areas of their contacts with the working tubes.

The results of experimental studies on the properties of a capillary liquid bridge in the gap between two glass spheres of an equal diameter are presented. It is shown that for the case when the diameter of the spheres is much larger than the capillary scale of liquid, the shape of the capillary liquid bridge can be described as a figure formed by two “drops”, touching the spheres, and the central catenoid. The contact angle between the “drop” and the sphere depends on the effective mass of the “drop”, and the relative position of the catenoid and the “drops” is set by the condition that the contact angle between them is equal to zero. In the field of gravity, the position of the minimum cross section of the catenoid does not coincide with the middle of the gap between the spheres and is determined by the magnitude of the surface energy and the way how the mass of liquid in the bridge is distributed over the “drops” and the catenoid.

The article describes the main stages in the development of biological methods for protecting forests from the caterpillars of the Siberian moth Dendrolimus sibiricus Tschetv. in Russia, from the first half of the 20^th century to the present. It has been shown that the use of bacterial preparations is of the greatest importance in the practice of forest protection; Lepidocide is currently the most widely used biopesticide. Previously, there was a viral preparation as a means of protection, but currently there are no viral preparations approved for use. Information on the development of fungi preparations is given, but it is emphasized that effective and reliable fungi preparations have never been available to combat this pest. A detailed historical analysis of the development of the classical biological control in forest protection from the Siberian moth is given. Cases of successful use of the egg parasitoid Telenomus tetratomus Kieffer and the technology by which this entomophage was used are described. The reasons are discussed that the use of this species has not become an important part of the biological protection system of taiga forests. The authors are convinced that the use of such biological agents of forest protection as entomophages, pathogenic fungi and viruses is possible only in those cases when suitable technologies of application and bio-production will be developed for each of them. Bacterial preparations are widely used in the practice of forest protection from Siberian moth due to the well-developed production technology, and the similarity of the technology of their use with chemical pesticides, while guaranteeing a reliable result.

Models of the population dynamics of forest insects are considered based on the concept of an outbreak as a first order phase transition of the (this sentence is not complete) As objects of the studies, the population of the Siberian silkmoth in Siberia and the Far East, the population of the pine moth in Europe, the population of the gypsy moth in the Urals, and the population of the gray larch leaf worm in the Alps are considered. In this work, models fo same species of forest insects are considered, that make it possible to estimate the critical population densities and, in this regard, to propose algorithms, on the basis of which it is possible to make decisions on the implementation of protective measures. A model of the population dynamics is considered as an analog of a phase transition in physical systems to describe the dynamics of the population. An algorithm for transforming of population dynamics time series is proposed to reduce the level of errors in the course of density counting of pest populations. A state function is proposed as a characteristic of population dynamics, calculated as the reciprocal of the probability of finding a population in a state with a given population density. The functions of the state of populations with modes of outbreaks are characterized by the presence of two local minima and one local maximum - a potential barrier. A method is proposed for calculating the functions of state of populations based on data from time series of population dynamics, characteristics of state functions are described, such as local stable densities, critical and semi-critical density, susceptibility of the state function to changes in population density, and the half-width of the potential barrier. Indicators are introduced - indicators of the risk of outbreaks. Assessments of the risks of outbreaks are given for the studied species of phyllophagous insects.

Regularities of micro and macro-spatial distribution of individuals of Siberian silkworm populations during an outbreak of mass reproduction are considered. When studying the spatial distribution of the Siberian silkworm, a model of the distribution of individuals of the Siberian silkworm among fodder trees on sample plots was considered and the shape of areas damaged by the Siberian silkworm was studied. Additionally, a model of long-term spatial dynamics of insect pest’s population centers is considered. To assess the micro-spatial distribution of individuals on the territory, the spatial dynamics of the distribution of Siberian silkworm caterpillars on trees at different stages of the pest population gradation are considered. To describe the distribution of insects over trees on test plots, a model is proposed - an analogue of the model of phase transitions of the second kind in physical systems. To describe the “movement” of the boundaries of the center of mass reproduction of insect pests, the model of “viscous fingers” is considered and the fractal characteristics of the boundaries of the centers are calculated. By assessing the fractal dimension of the outbreak boundary, it is possible to calculate the ratio of the population density and the time of development of the forage object, and from the fractal dimension of the boundary between the outbreak and the undamaged forest, it is possible to estimate the nature of the further development of the outbreak. Also, based on a single measurement of the structure of the focus boundaries, one can try to estimate the fractal dimension of the focus and the risk of its further development. The considered models were verified according to the observations of various authors. When constructing and verifying the models, we used the data of the counts of the Siberian silkworm population and the population of trees in the foci of its mass reproduction, and remote data on the areas and shape of the foci. Using the proposed models, it is possible to estimate the critical characteristics of the population density and the shape of the foci of mass reproduction of pests at different phases of population gradation based on the data of counts and remote observations.

It is known that weather affects the development of outbreaks of Siberian silkmoth Dendrolimus sibiricus Tschetv. breeding. In this regard, the purpose of these studies was to study the influence of weather factors - temperature and precipitation on the possibility of developing of Siberian silkmoth population outbreaks. For a correct assessment of the influence of climatic factors on the dynamics of the number of forest insects and the development of outbreaks of pests, the concept of necessary and sufficient weather conditions was introduced to facilitate outbreaks of phyllophages. An approach is proposed to assess whether certain weather conditions are necessary or sufficient for the development of outbreaks of the Siberian silkworm in Krasnoyarsk Krai. Selyaninov’s hydrothermal coefficient (HTC) was chosen as an integral indicator of weather conditions: the ratio of the amount of precipitation for a certain period to the average temperature for this period. The Bayesian approach was used to calculate the conditional flare probabilities. For various forests in the territory of Krasnoyarsk Krai in which outbreaks of the Siberian silk moth were observed, analyses were carried out for May, June, July, August, and September in the period from 1980 to 2017. Analysis of the relationship between weather conditions and the development of outbreaks of the Siberian silk moth showed that a necessary condition for the occurrence of an outbreak of this pest in Krasnoyarsk Krai is dry and warm weather in May of the year preceding the onset of the outbreak. However, dry and warm weather in spring - early summer is not a sufficient condition for a future outbreak, and additional indicators are needed to predict the outbreak. Nevertheless, when the weather with HTC < 1 is realized, it is necessary to start carrying out a more detailed monitoring of the state of the pest population. It seems that the proposed calculation method can be used to assess the effect of weather on the development of the population not only for the Siberian silk moth, but also for other species of forest insect pests.

The Siberian silk moth Dendrolimus sibiricus Tschetv. is one of the most dangerous pests of taiga forests. Large-scale outbreaks of the population and the expansion of the pest’s habitat attract scientists to the study of insect sex pheromones. The Siberian silk moths use pheromones to attract mating partners. Pheromone communication is a complex multistage process, including the synthesis of pheromone, the spread of odorous substances in the environment, the perception of the pheromone signal by other individuals, and the behavioral response of individuals receiving the signal. Effective transmission of the pheromone signal is ensured due to the preservation of the chemical composition and conformation of molecules during propagation in the air, as well as their ability to decompose at a certain time under the influence of external factors. The stability and reactivity of molecules is determined by their physicochemical characteristics. Structural and spectral properties of molecules were investigated using methods of computer molecular modeling. Quantum chemical calculations were performed using the density functional theory B3LYP/DFT, which is widely used to study small organic molecules. A detailed analysis of the atomic and electronic structure of molecules in the ground and excited states was carried out, and the absorption spectra of molecules were calculated. The wavelengths and absorption intensity were determined. Based on the data obtained, a conclusion was made about the stability of pheromone molecules to the effects of sunlight, an assessment was made of the possibility of changing the chemical composition and structure of molecules as a result of absorption of ultraviolet radiation. The calculated data obtained were compared with the data on the daily patterns of insects.

To assess the state of plantations in vast areas of boreal forests, modern methods are needed that allow obtaining information quickly with minimal labor costs. The existing assessment methods are either associated with labor-consuming ground-based observations, or they make it possible to measure the damage that has already occurred using remote sensing data (satellite, aeronautical observation methods). Methods for analyzing the state of forest stands in large areas (such as taiga forests in Siberia) based on remote sensing data are proposed. As an indicator of the state of stands, it is proposed to use the susceptibility index of vegetation index during the season (NDVI) to changes in the radiation temperature (LST), obtained from satellite data of the Terra/Aqua system. The index was calculated as the transfer spectral response function in the integral equation between NDVI and LST. The analysis was made for two types fir stands of Krasnoyarsk Region taiga zone - territories that since 2015 were damaged by of the Siberian silkmoth Dendrolimis sibiricus Tschetv. caterpillars and nearest intact areas. It is shown that indicators of stands’ susceptibility to environmental changes on the studied test plots changed significantly 2-3 years before pest population outbreaks and can be taken into account when assessing the risk of outbreaks. This distinguishes proposed indicator from assessments of the vegetation cover state, which register a significant defoliation of forest stands and cannot be used for forecasting.

The article is devoted to the research of natural regeneration of the pine forest, which suffered from outbreak foci of Siberian moths Dendrolimus sibiricus Tschetv. The studies were carried out in far south of Tomsk Oblast in the subzone of the subtaiga on the southern border of closed Siberian pine forest area on West Siberian plain in 2011-2015. The results of the research of the dynamic of the undergrowth condition of the Siberian pine forest with different defoliation level of maternal canopy were presented in the article. To assess vitality of the undergrowth of various species, a reference method was used that is based on comparison of morphological inventory indicators of young plants with pre-selected standard items. It was shown that the vitality and survivability of the undergrowth influence the damage level of the tree stands by the Siberian moths. In completely-eaten stands, dark coniferous undergrowth of preliminary reforestation died and broad-leaved trees took up the major portion in the composition of the undergrowth. In the stands of heavily weakened trees the increase in portion of aspen was determined. Under the canopy of the plantation with weak defoliation, the dramatic changes in species composition of the undergrowth did not take place. Prevalence of dark coniferous species is still being observed but its quantity is not enough for successful reforestation. The changes of lighting did not cause either positive or negative reactions of Siberian pines or fir trees undergrowth to an increase in lighting.

The first note about the outbreaks of the Siberian moth Dendrolimus sibiricus Tschetv. (Lepidoptera, Lasiocampidae) was published 125 years ago. The pest outbreaks of the 1950s and 1960s are poorly documented in Krasnoyarsk Krai. For the first time we provide the details of planning, organizing and implementing large-scale measures to combat the Siberian moth outbreak in the second half of the 1960s. The outbreaks that occurred in the southern taiga forests of the region covered an area of 260 thousand hectares. The maximal insect density reached 7 thousand caterpillars per one fir tree. The outbreak was successfully suppressed thanks to its early prediction, development and implementation of surveillance methods, as well as methods of aerial treatment and assessment of efficiency of protection measures. In 1967-1969, the crews of 45 An-2 aircraft during 2.5 thousand flight hours treated more than 200 thousand hectares of the pest foci with the dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane solution. Over 1,100 people took part in the aeronautical work, including about 250 engineers and technicians. During the 1960s outbreak, the total labor costs for airborne combat with the Siberian moth exceeded 22.000 man-days. To control the Siberian moth, for the first time, high concentration of the insecticide was used, i. e. 20 % oil solution of DDT + hexachlorocyclohexane, with ultra-low consumption rates of working solutions (from 3 to 5 l/ha). The Siberian moth outbreak that occurred on in Krasnoyarsk Territory in the mid-1960s clearly demonstrated high importance of cooperation between scientists and forest protection practitioners. The joint work contributed to the initiation of a specialized institution - the Station (later the Center) of forest protection of the Krasnoyarsk Territory, which leaders in different years were the researchers from the V. N. Sukachev Institute of Forest Sib. Br. Rus. Acad. Sci.

The principles of organization in the forest protection system and the principles of decision-making in the tasks of carrying out protective measures are discussed. The problem of assessing costs and risks in the course of forest protection measures is considered. The functioning of a security service is better understood when viewed as an agent-principal system. In the «agent-principal» system, agency relations are established when one person - the principal or the owner (principal) - transfers certain rights to another person - the agent. In this case, the agent, in accordance with the contract concluded between them, is obliged to act in the interests of the principal in exchange for remuneration. The agent problem, well known in the contract theory of economic systems management, is that if the managing manager is not the owner (principal) of the control structure, then there is a mismatch between the management goals of the principal and the agent. Each of them - both the agent and the principal - has their own interests. The agent has its own interests, and he tends to follow the goals of the principal only to the extent that the contract encourages him to do so. In such a system, there is an uneven distribution of information between the agent and the principal. By analogy with such economic systems, the system of forest protection is considered, where the state or the region is the principal, and the heads of regional structures of the forest protection system have information about the state of the forest ecosystem and the right to make managerial decisions. The features of the functioning of such a system are discussed. The problem of decision-making when carrying out protective measures is considered. The main feature of the decision-making process when protecting a forest from an attack by insects is that there is a lag between the moment a decision is made to switch to protective measures and the moment when protective measures begin. A decision-making model that minimizes the risks of errors is considered. The proposed approach makes it possible to evaluate the efficiency of decision-making in forest protection tasks, depending on the management principles used. The optimal decision on carrying out protective measures will be while minimizing errors of the first and second genera and the risk of damage to the plantation. In the proposed decision-making model, the coefficients for a certain type of pest can be determined from long-term survey data, while as an indicator of the state of the population, it is possible to use not only the values of its density, but also other indicators.