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The H₂O absorption lines broadened by the air pressure were recorded using IFS 125HR Fourier spectrometer in the spectral region 3000-7500 cm^-1. The H₂O absorption line intensities are determined for the modified Voigt profile which takes into account the dependence of the broadening on the speed of colliding molecules. The comparison with literature data is carried out. The intensities of the H₂O absorption lines obtained in this work can serve both as a basis for improving the calculations of absorption lines and for various atmospheric applications that require the high precision intensity values.

In this paper, a two-dimensional, steady, laminar boundary layer analysis is presented to analyze numerically the internal heat generation and Soret-Dufour effects on mixed convection flows of power-law fluids adjacent to a vertical flat plate maintained at variable heat flux and variable mass flux conditions in a Darcy porous medium. The Ostwald-de Waele power-law model is utilized here. The transformed governing equations are solved by the Keller box method. After performing comparisons with previously published results, good agreement is obtained.

A modified form of differential equations is proposed that describes physical processes studied in applied mathematics and mechanics. It is noted that the solutions of classical equations at singular points may experience discontinuities of the first and second kind, which have no physical nature and are not observed experimentally. When deriving new equations describing physical fields and processes, we consider not infinitely small elements of the medium, but elements with finite dimensions. As a result, the classical equations include non-local functions averaged over the volume of the element and are supplemented by the Helmholtz equations establishing the relationship between non-local and actual physical variables, which are smooth functions without singular points. Singular problems of the theory of mathematical physics and the theory of elasticity are considered. The obtained solutions are compared with the experimental results.

Based on Haddad's small crack theory, a new comprehensive fatigue life model of the TC4 titanium alloy is proposed through combining the modified Chaboche model and the crack propagation formula considering the crack closure effect. The results of model validation and comparisons show that the crack initiation life and crack propagation life predicted by the model are consistent with the test data under cyclic loading of the alloy.

In this paper, a novel modified strip yield model is proposed to evaluate the load-bearing capacity of an infinite isotropic plate containing five collinear straight cracks with coalesced yield zones. It is assumed that these yield zones are subjected to a linearly varying yield stress. The well-known complex variable method is used. To assess the results, numerical studies are carried out for different cracks lengths. Good agreement of the results obtained is observed with previously published data.

A simulation mathematical model is presented that describes the process of vitrification and devitrification of the binder. Theoretical estimates of the effective physical and mechanical parameters of the material and microstructural stresses with temperature change are obtained. A numerical scheme has been developed (in the form of a computer program) that makes it possible to implement the modeling technique. Estimates of elastic moduli and submicrostructural stresses are obtained. The results can be used to select the composition of the material and its parameters at the final stages of the technological process of creating a polymer binder.

The plastic instability of an internally impulsively loaded thin-walled end-closed cylindrical shell with plastic anisotropy is investigated. The cylindrical shell is assumed to be made of a ductile material. Based on Hill's orthogonal anisotropic yield criterion, the instability strain of a thin-walled end-closed cylinder is derived, which takes into account the effects of the plastic orthotropy and strain rate. The numerical analysis of the instability strain is conducted. The results show that the instability strain for a thin-walled end-closed cylindrical shell depends upon the deviation from isotropic plasticity and the strain rate.

The Bhatnagar-Gupta method is used to consider a solution to the problem of torsion of a rod with a circular cross section cut in the longitudinal direction from a transversally isotropic plate under creep conditions is considered. It is shown that the solution agrees satisfactorily with the lower and upper estimates of the twisting angular velocity obtained on the basis of the principles of minimum total power and additional scattering, as well as with the results of numerical simulation in the Ansys finite element program. Based on the Bhatnagar-Gupta solution, the possibility of using the method of characteristic parameters for estimating the stress-strain state and the rate of the twist angle of a rod under the action of a constant moment is shown.

Theoretical aspects of natural gas liquefaction at a high-pressure gas distribution station using the Claude open cycle are considered. Based on the thermodynamic analysis of the cycle, it is shown that there are two modes of gas liquefaction: if the initial gas pressure is higher than the critical one, the liquefaction process by throttling the production flow can be considered as isenthalpic; if the initial gas pressure is below the critical one, the process of gas throttling and liquefaction should be considered as a set of processes of isentropic expansion and subsequent adiabatic expansion and deceleration of the production flow. For both modes, mathematical models and algorithms for numerical calculation of the natural gas liquefaction process have been developed. The value of the maximum yield of liquefied gas was estimated, taking into account its real properties and existing restrictions. It is shown that the obtained calculation results are in good agreement with the known experimental data.

A novel dual-axis solar tracker (DAST) based on a super-twisting high-order sliding mode controller (STHOSMC) is proposed. The surface of the photovoltaic panel is perpendicular to the solar radiation at all times. The super-twisting algorithm due to its super-spiral curve can precipitate the convergence and reduce the chattering phenomenon. Hence, the STHOSMC can promote the tracking performance of the DAST and smooth its tracking motion without the need to obtain the sliding variable time derivative. Various scenarios of the sunlight and temperature have been considered to deal with the tracking performance of this proposed controller. The simulation results under these scenarios have validated that the proposed controller accurately extracts the maximum electrical energy from the sunlight. To further evaluate the performance of the STHOSMC-based DAST, its prototype model has been provided and tested.