The article contains an analysis of the shallow elastic spherical shell on a rectangular plan, reinforced with ribs along its contour, under the uniformly distributed load. The problem is solved numerically with the variational-difference method, considering the geometric nonlineaity and the shear deformations of the shell and the ribs. As a result, the dependencies of the critical load on the shell stiffness and the ribs stiffness are obtained.

Keywords: shallow spherical shell, ribbed shell, stability, bending stiffness, geometrical nonlinearity, variational-difference method, critical load

This article discusses the ways and methods of modifying bitumen with crumb rubber obtained from used recycled car tires. A method for modifying bitumen with crumb rubber in a two-stage technological process is proposed. The main modifiers are considered, the analysis of data from literature sources on the modification of bitumen with polymers to improve the physical and mechanical properties is given. Own research data on the modification of bitumen with crumb rubber are presented. The main conclusions are made, the analysis of the results obtained, and recommendations are made for the further use of bitumen modified with crumb rubber in a two-stage technological process.

Keywords: crumb rubber, bitumen, modification, polymer, improvement, quality, recycling, analysis, research

Numerical solution to the problem of heat transfer in boundary layers transparent Strip on the walls, exposed on the opposite side of the radiant-convective heating. Study of influence of mode parameters on heat transfer process of tasks carried out in the case of the gradient flow and included the most typical variants of transportation processes. The purpose of the real work is studying of processes of transfer at non-linear boundary conditions, obtaining approximate and analytical decisions non-linear warm and a mass transfer, establishment of communication between regime parameters and physical interpretation of results of a research. Also some conjugate problems of heat exchange in the presence of radiation are studied. The analysis received decisions is carried out. The executed research allowed to establish that existence of a transversal overflow of heat in a wall and also the radiation of a surface have significant effect on the nature of distribution of the surface temperatures.

Keywords: boundary layer, convection, radiation, gradient flow, conjugate heat transfer

Numerical solution of the problem of heat transfer in the boundary layers of transparent gas wall, exposed on the opposite side of radiant-convective heating. The energy dissipation due to viscosity is negligible, the wall is thermally thin, and the physical properties of the medium do not depend on temperature. The aim of this work - finding the local heat transfer coefficients (Nusselt number) needed for the analysis of heat exchangers. When solving the problem of nonlinear transfer functions linearizing method is used, based on which numerical scheme for computer calculations was constructed. The intensity of the local heat transfer in the boundary layer is determined by the number Kx = Nux / Nux0, where the value Nusselt numbers refer to the conditions under consideration of the problem of heat exchange (Nux) and constant surface temperature (Nux0). From a physical point of view, non-dimensional parameter Kx is a measure of the intensity of heat transfer in the boundary layer on a nonisothermal surface compared to heat transfer when the wall temperature everywhere the same. The analysis of this research showed that in radiative-convective heating number Kx on the front edge of the plate takes the largest value of Kx ≈ 1,37 corresponding to a constant heat flux on the wall. It is also shown that the relative temperature of the incoming flow has a significant impact on the value of Kx. The effect of this setting is especially evident in the processes when dominated by the effect of radiation and related to the nonlinearity of the transfer processes. The analysis revealed the influence of basic parameters of heat transfer on the development of transport processes in the boundary layer by heating radiation and convection simultaneously.

Keywords: Boundary layer, convection, radiation, radiation-convection heating, high temperature gas invironment, linearizing function