Tver State Technical University

The article is devoted to the study of the role of smart urban technologies in the development and commercialization of electric transport in Russia. The purpose of the work is to analyze the impact of digital platforms, intelligent control systems, and infrastructure solutions on the integration of electric vehicles into the urban transport system. The article assesses the regional specifics of the dynamics of electric transport. It is argued that the digitalization of the urban environment contributes to the formation of sustainable and environmentally friendly transport systems, accelerating the implementation of innovative solutions in megacities. The scientific novelty of the work lies in identifying the key factors that determine the commercial potential of electric transport within the framework of the smart city concept.

The article presents results of a complex loading experiment on thin-walled brass L63 tubular specimens, demonstrating a highly non-trivial relationship between stresses and strains during elastoplastic deformation. The experimental program, as well as the interpretation and discussion of the obtained data, are based on the terminology and theoretical provisions of A.A. Ilyushin’s theory of elastoplastic processes. The experimental study was carried out in the deviatoric strain space on the automated testing machine SN-EVM under combined axial tension-compression and torsion loading of thin-walled tubular specimens. A distinctive feature of this study was the complex curvilinear strain trajectory consisting of five circles internally tangent at the coordinate origin. Each trajectory segment featured varying curvature values and circle center positions along the axis. According to A.A. Ilyushin’s definition, this trajectory qualifies as smooth since it contains no break points. During the experiment, the scalar and vector properties of the L63 brass material were studied. It was experimentally established that a change in the trajectory curvature causes a “dive” of stresses on the stress-strain diagram, which is similar to the dive that appears when there is a break angle in the trajectory, for example, in two-link broken trajectories. It was also established that the obtained experimental diagrams reflecting the vector properties of the material have a pronounced oscillatory behavior. The experimental results will be useful for verification of existing mathematical models of plasticity theory.

The article presents the results of an experimental study of complex elastoplastic deformation of L63 brass along two-link broken strain trajectories in the deviatoric strain space. The description of the experimental program, presentation and discussion of its results are carried out in the vector representation of stresses and strains using the terminology and approaches of A.A. Ilyushin’s theory of elastoplastic processes. The experiments were carried out in the mechanical testing laboratory of Tver State Technical University using the automated testing machine SN-EVM under combined loading of thin-walled tubular specimens with axial force and torque (P + M experiments). The loading process was assumed to be isothermal, and the strains were considered small. The material of the specimens was sufficiently isotropic initially, as confirmed by experiments under simple loading. The test programs were implemented in the deviatoric space of strains (rigid or kinematic loading). Two-link broken trajectories with the first link length of 3% and fracture angles of 90°, 135°, and 180° are investigated. Experimental diagrams characterizing the scalar and vector properties of the L63 brass material are presented. Approximations of deformation diagrams under simple and complex loading are proposed. The research results can be used in constructing mathematical models of plasticity theory.

For the case of a simplified plane stress state and plane deformation trajectories, the constitutive relations between stresses and strains beyond the elastic limit in derivatives with respect to the parameter of tracing the loading process are obtained. The necessity of taking into account the sign of the approach angle between the tangent to the strain trajectory and the stress vector in the constitutive relations is shown.

This work is aimed at the search of optimal conditions of selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE). The main question was if the common slurry reactors are suitable for this reaction under ambient hydrogen pressure with the use of environmentally friendly solvents. Thus, we investigated the effect of the reactor type (shaker-type or slurry), temperature and solvent nature (isopropanol, n-butanol or toluene were used) on the behavior of a palladium catalysts (1 wt.% of Pd) deposited on amorphous aromatic polymers in the reaction of selective hydrogenation of MBY to MBE. Aromatic polymers were synthesized by the one-step cross-linking of such monomers as benzene and naphthalene using methylal as an external cross-linking agent. These polymers are simple in synthesis and possess high porosity (specific surface area is about 1000 m2/g) that favors stabilization of Pd nanoparticles into the polymers� pores. It was demonstrated that synthesized catalysts allow achieving high selectivity with respect to MBE (95-96% at almost complete conversion of MBY). Moreover, since the reaction was carried out at ambient hydrogen pressure, the method of hydrogen supply and sampling has strong influence as well as the nature of the solvent, which affects not only the hydrogen partial pressure, but also the hydrogen solubility and the adsorption of the reagents.

Studies of natural processes of river water chemistry formation and the effect of anthropogenic factors on it remain a topical task of hydrochemistry. In July 2021, water quality was assessed based on hydrochemical indicators of the upper reaches of 29 small rivers in the Volga River basin within the Tver region. The location of most of the gages was selected, if possible, in homogeneous landscape conditions of catchments, minimally affected by economic activity. The obtained characteristics can be considered as close as possible to natural background indicators for the summer low-water period. The analysis of spatial differentiation of natural factors was carried out on the basis of landscape maps, geochemical and hydrogeological cartographic materials of different years of publication. The set of hydrochemical characteristics was processed using the method of hierarchical cluster analysis. Significant spatial differentiation of the chemical composition of waters was revealed, and landscape diversity was not found to play a clear determining role. The chemical composition of water in small rivers is mainly influenced by two factors. The high degree of swampiness of the catchment area leads to an increase in the concentrations of Fe, organic matter by COD and PO, phenols and color index in surface waters. The presence of channel lakes levels out this factor to some extent, which is most noticeably manifested in the association of river waters of the Volga and Selizharovka. The second factor is the recharge by deep groundwaters, which increase the TDS of river waters, the content of the main ions, F, Sr, and P, and the leaching of silicates from bedrock. The combined effect of both factors apparently causes the high concentrations of Mn characteristic of the region.

For plane plastic deformation of an anisotropic medium, the stress state coefficient is determined. Graphs are constructed that characterize the effect of anisotropy on deformation amplification. The coefficient of anisotropy influence is given, showing how much the deformation force for an anisotropic medium is greater (or less) than for an isotropic one. It is shown that plane plastic deformation is possible only in a certain range of yield strength ratios.

The laws of thermal radiation from gas volumes of flares of steam boilerfurnaces of power plants, combustion chambers of gas turbine installations of power plants are described.Heat transfer is calculated in the furnace of a steam boiler of a power unit with a capacity of 800 MW.The distribution of temperature, heat fluxes of the flame and deposits in the tubes is significantly non-uniform, which adversely affects the operation of the furnace. A steam boiler furnace has been developed in which the flame temperature and pollutant emissions are reduced and heat fluxes across heating surfaces are equalized.