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The results of the numerical simulations on optical radiation focusing by a cluster of identical nanospheres densely packed into a spherical volume (a "metaparticle") are presented. The parameters of the focal region (intensity, longitudinal and transverse dimensions) formed by metaparticles with different internal structure are calculated. We show that in certain cases, the problem of focusing optical radiation by a globular cluster of nanoparticles can be reduced to the problem of light focusing by a homogeneous spherical particle with an effective refractive index obtained from the effective medium theory. Moreover, certain globular cluster topologies make it possible to improve the optical focusing in the near-field region, in particular, by increasing the focal intensity or enhancing the spatial localization of the focal area.

The conditions for the occurrence of extreme concentrations of submicron particles and black carbon in their composition in the surface air layer are analyzed on the basis of monitoring measurements of aerosol characteristics and acoustic sounding of the lower air layer in the winter periods of 2016-2022 in Akademgorodok, Tomsk. It is shown that with a combination of surface air temperature inversion and weak (up to 1.5 m/s) wind (air stagnation), the average aerosol characteristics under study increase by up to 3 times, and with a weak northwest wind, up to 7-8 times relative to the season averages. It is found that under several-day air stagnation conditions, the typical daily variation, characterized by the afternoon minimum, is transformed. The increase in the concentrations continues until 15:00; the values exceed nighttime minimum by 1.8 times. On other days of the winter season, the maxima occur at 10:00 am, with the excess of the concentrations of submicron particles by 1.2 times, and of black carbon, by 1.5 times over the nighttime minima.

A mathematical model is proposed that simulates the acquisition and processing of hyperspectral remote sensing data on subtle fragments of environmental pollution (garbage) comparable in size with the spatial resolution of the observation equipment. Spectral mixing of “objects” with “background” is provided by a special coefficient, which takes into account that the area of each element of a scene template related to the “object” is only partially filled with its spectral characteristic, and the rest of the area, with the background characteristic. The options for calculating the probability of detecting objects depending on the observation conditions specified with the MODTRAN atmospheric model are considered. The difference between the model data and real experimental results is no more than 10%.

The results of synchronous lidar observations of the transfer of atmospheric aerosol fields over Lake Baikal during the summer expedition of 2018 are presented. The experiment was carried out using two lidars, one of which was located on a ship, and the second, at a distance of 732 m at a stationary station. Based on the correlation analysis of the lidar data, the transfer time of atmospheric aerosol heterogeneities between observation points at different altitudes above the mountain basin is estimated. It is found that the transfer time is 5 min 20 s for the altitude range 100-350 m, 7 min 12 s for 1250-1500 m, 5 min 20 s for 2100-2500 m, and 6 min 24 s for the range 4200-4300 m. Such uneven altitude distribution of the transfer time of aerosol objects is due to the complex air flow circulation in the mountain basin.

Changes in the base height of the lower layer cloudiness and cumulonimbus clouds over the territory of Western Siberia are analyzed based on laser data for the period 2010-2021. We established that, in general, there is a decrease in the base height of lower clouds and its increase for cumulonimbus clouds. An increase in the base height of lower cloudiness occurs from north to south. More meridional distribution is obtained for cumulonimbus clouds. The seasonal course of the lower cloudiness and cumulonimbus clouds base height in the south of the territory has a maximum in summer. Two maxima are observed in the center and in the north: for lower cloudiness in summer and spring and for cumulonimbus clouds in winter and summer. The results of the cluster analysis show a significant difference in the base height for cumulonimbus clouds (in comparison with lower cloudiness) at different stations, which is presumably due to differences in earth’s surface characteristics and station height above sea level, as well as regional features of atmospheric circulation and convective processes.

Characteristics of air temperature inversions in the atmospheric boundary layer (frequency of occurrence, intensity, and depth) up to a 1-km height are analyzed based on experimental MTP-5 (meteorological temperature profiler) data obtained in 2020-2022. Air temperature profiles were measured simultaneously at a site with natural landscape (Tomsk suburbs) and over an urban territory (Akademgorodok, outskirts of Tomsk). Temperature inversions were observed in approximately half of the observation period. The statistics of various forms and types of inversions for different seasons is presented. The correlation between the inversion intensity and weather parameters in the surface air layer is considered. A significant effect of the wind direction on the inversion intensity is noted.

The results of an experimental study of the possibility of burning separated and discharged to the Earth's surface are presented on the example of the design of elements of the head fairing of a launch vehicle. A new scheme of a honeycomb-free three-layer construction of combusted elements of the head fairing using a charge of high-energy material is proposed. Based on the formulated requirements for the characteristics of the charge and analysis of the results of thermodynamic calculations, the basic compositions of high-energy materials (HEMs) were selected. The energy and strength characteristics of the selected HEM compositions are experimentally determined, and the patterns of their combustion at subatmospheric pressure are determined. The results of laboratory tests of the combustion of elements of the structures under consideration with a VEM filler charge showed the possibility of partial utilization of spent parts of the launch vehicle.

The purpose of the present study is to investigate the detonation in air containing an n-heptane droplet cloud and the effect of the droplet size. A finite volume solver is developed to simulate the two-phase reacting compressible flow using a single-step reaction mechanism. The focus is on the impact of the droplet size on the detonation wave pressure and velocity. For the physical situation considered, the upper limit of the droplet size is determined to ensure self-sustained detonation, and it is shown that medium-size droplets initiate a stronger detonation wave than the gas fuel detonation or than large-size droplets. The distribution of the flow properties behind the wave is analyzed to demonstrate the observed behavior of the droplet size.

The explosion process of the flake aluminum powder-air two-phase flow is experimentally studied in a large-scale long straight horizontal tube with a length of 32.4 m and an inner diameter of 0.199 m. The deflagration-to-detonation transition (DDT) of the aluminum powder-air mixture is analyzed after being ignited by a 40-J electric spark, and the DDT of the mixture at different mass concentrations is compared. The results show that self-sustained detonation can be achieved in the range of 286 ÷ 532 g/m³ of the flake aluminum powder concentration, and the DDT process of the aluminum powder-air mixture at the concentration of aluminum particles 409 g/m³ (optimal concentration) is analyzed in detail. The detonation velocity and detonation pressure at the optimal concentration are 1690 m/s and 58 bar, respectively. During the self-sustained detonation stage, the detonation overpressure of the multiphase fuel-air mixture exhibits a typical constant oscillation characteristic, while the detonation velocity remains stable. In addition, a double-headed mode helical detonation phenomenon is observed in the detonation wave front of the aluminum powder-air mixture. The structure of the detonation wave, the flow field parameters, and the interaction between the shock wave and the three-wave point trajectory are analyzed. The detonation cell size at the optimal concentration is approximately 486 mm.

Experimental and numerical studies of premixed methane-air flame dynamics in an obstructed chamber are carried out. In the experiment, high-speed video photography and pressure transducer measurements are used to study the combustion dynamics. In the numerical simulation, three subgrid-scale viscosity models and three subgrid-scale combustion models are selected to evaluate their individual predictions compared to the experimental data. The high-speed photographs show that the flame propagation process can be divided into four typical stages. When the flame front passes through the obstacle, two distinct vortex structures are formed. The volute flame is the result of the flame-vortex interaction. In addition, the combustion regime experiences a transition from “wrinkled flamelets” to “corrugated flamelets” and finally arrives at a “thin reaction zone regime.”