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The spatial and temporal variability of forest floor moisture characteristics is analyzed on the basis of the Canadian Fire Forest Weather Indices (CFFWIS) for the territory of Western Siberia (45-75° N, 60-90° E) over 2016-2021 for the first time. The floor moisture effect on the number of wildfires (hotspots) during the warm season (March-October) is assessed. The results are given for different natural zones. Statistically significant correlations are found between hotspots and floor moisture at a depth of 7 cm only in some spring and summer months (correlation coefficient is up to 0.54). The strongest effect (correlation coefficient is up to 0.60) on wildfires is observed for floor moisture at a depth of 1.2 cm in the south of Western Siberia in April. Thus, it can be concluded that the forest floor moisture is an important parameter in description of conditions for fire initiation and development. However, the question about its effect on the wildfire behavior remains open and requires additional research accounting meteorological and atmospheric conditions. The results can be used in future for solving problems of forecasting the potential fire danger.

The impact of aerosol sources on the atmosphere pollution of Russian Arctic sector is underestimated. The newly aerosol station was installed on Bely island (Kara sea) in August 2019, it is located on the way of air mass transportation from industrial regions of Western Siberia to the Arctic. Continuous aethalometric measurements of short leaving climate tracer - black carbon are carried out. They showed the seasonal variability with high values from December to April (60 ± 92 ng/m³) and low in June-September (18 ± 72 ng/m³). Pollution events with concentration higher background are identified. Regional distribution of fossil fuel and biomass burning sources are obtained by the concentration weight trajectory model. Impact of gas flaring from oil and gas extraction areas of Western Siberia, Volga-Ural, and Komi Republic is the most pronounced during the cold period while the wildfire smoke emissions are dominated in warm season. The difference between the black carbon concentrations in ultraviolet and infrared wavelength regions serves as a marker of biomass burning impact on the aerosol composition, indicating the residential wood combustion and agriculture and wildfires during cold and warm season, correspondently.

A technique has been developed and a calculation has been made of the irradiance of the entrance pupil of a ground-based optoelectronic system (OES) from a cylindrical space object illuminated by the Sun at night. The results of calculating the minimum irradiance and corresponding stellar magnitude at the input pupil of the OES are presented with a signal-to-noise ratio at the output of the photodetector matrix with a current equal to 7 in the wavelength range of 0.45 ÷ 0.85 mm. The dependence of the signal-to-noise ratio on the distance to the space object for its three different sizes is constructed. The program ROSN-1 was developed and its control panel was presented for calculating the characteristics of ÷ 0.85 mm was presented, and the possibilities of this program were explained.

The features of high-power and high-contrast imaging in a bistatic laser active optics system (laser monitor) are considered. In the developed system, a brightness amplifier has a larger volume than an illumination source, which makes provides for high-power contrast images of micro objects. For the first time, the influence of the time shift between a superradiance pulse of the amplifier and the time of signal arrival at its input on the contrast and power of images formed by one pulse was was ascertained. It is shown that artifacts formed as a result of the superluminous radiation "parasitic" reflection and scattering from optical circuit elements significantly reduce the contrast and power of the generated signals. This effect can be eliminated by the generation of an amplifier input signal before the generation of amplified spontaneous emission. The optimal delay is 1 ns.

An improved Ritchie-Knott-Rice failure criterion, namely (4δ_t, σ_22c) criterion, for the A515-70 steel is studied with allowance for the specimen geometry, specimen temperature, and initial crack length. The results show that the (4δ_t, σ_22c) criterion can effectively predict the cleavage fracture. Results of studying the possibility of using a dimensionless function for determining the fracture toughness are reported.

The possibility of phase transitions (martensitic transformations) in shape-memory alloys is evaluated using the concept of eigenmoduli and eigenstates from the linear theory of elasticity. For alloys with cubic and hexagonal lattices, the matrices of elastic moduli and compl are given and expressions for their eigenmoduli and eigenstates are written. For cubic and hexagonal phases, the specific strain energy is presented as the sum of six independent terms corresponding to six orthogonal eigenstates. It is shown that depending on the ratio of eigenmoduli, there are six types of materials (alloys) with cubic and hexagonal symmetry. The specific strain energies in the cubic and hexagonal phases are compared. If the strain energy is greater in the hexagonal phase than in the cubic phase, the alloy can tend to return to its original state with lower energy. In addition, the strain energies in different phases can be compared using the formulas of the tensors closest in the Euclidean energy norm to cubic and hexagonal tensors. The energies are compared for some values of elastic constants.

For boundary-value problems, the Helmholtz equations in wedge-shaped domains, it is shown that in packed block elements corresponding to the same boundary-value problem can be combined taking into account the type of boundary conditions, also forming a packed block element. The result is verified using another method. It is shown that in the presence of corner points in the domain in which the boundary-value problem is considered, combining block elements does not involve additional complications. It is found that since the solutions of some boundary-value problems in continuum mechanics and physics can be represented as a combination of solutions of boundary-value problems of the Helmholtz equation, this approach can be used to study more complex boundary-value problems and design materials with mosaic structure.

Interaction between a thin viscoelastic layer and a rigid cylinder whose contacting end surface is nominally flat but has a microrelief is studied. The microrelief is modeled by a periodic system of axisymmetric indenters. Analytical expressions for the depth of indentation and the actual contact area are obtained using an approach based on consideration of micro- and macroscale levels. The effect of the surface microgeometry of the punch and mechanical properties of the layer on the time dependences of the indentation depth and the actual contact area.

A self-balanced stress field for an incompressible sphere is constructed based on a non-Euclidean model of a continuous medium. The total stress field is presented as the sum of the elastic and self-balanced fields. The requirement that there are no singular contributions to the stress field leads to the fact that the coefficients at the singularities of the elastic and self-balanced stress fields can be related by a linear transformation, ensuring the removal of singularities. The compensating role of self-balanced stress fields allows one to construct a nonsingular equilibrium stress field for a spherically symmetric state of a continuous medium.

A problem of damping vibrations of a smart structure consisting of elastic and viscoelastic materials and piezoelements with connected shunt circuits is considered. It is proposed to replace the classical resistor in the shunt circuit by an element made of an electroconducting material, in particular, a polymer material filled with graphene nanoparticles. This element plays the role of several resistors with different resistance values, which ensure multimodal damping of vibrations. A mathematical formulation of the problem of forced steady and natural vibrations of smart systems under consideration is provided, as well as results of numerical calculations, which show that graphene-based composites can be used for additional damping of vibrations of smart structures based on piezoelements.