No 2 (2023)

The influence of external wave action on the filtration of the fluid from capillaries into the tissue surrounding the capillaries and from the tissue into the capillaries is considered. Two mechanisms for increasing the filtration rate are established: nonresonant, associated with the asymmetry of the change in the permeability of the capillary surface layer and the tissue surrounding the capillary at adjacent half-periods of wave actions, and resonant, associated with an increase in the pressure drop caused by a pulse wave in the capillary, and a synchronous and in-phase increase in permeability due to wave actions. The established effects can find application in medicine for the intensification of transcapillary exchange and microcirculation in the circulatory system.

According to the estimation of experts, the number of breakdowns and accidents, as well as wear of parts of standard equipment, is 3–5 times (in some cases 8–10 times) greater during operation at low temperatures than under temperate climate conditions. Therefore, enhancing the quality of surfaces of various machines and mechanisms operating in the Arctic is relevant. This article suggests a method of combined processing that allows one to increase hardness, reduce roughness, obtain optimal residual stresses, and create regular surface microrelief to keep the lubricant on the surface. However, these properties must be maintained at temperatures down to –50°C. The effect of low temperatures on the surface layer of details after combined processing is studied. This work is useful for experts engaged in the design of machines for operation in the Arctic.

On the example of planar mechanisms with rotational pairs, a comparison is made of two types of graphs that describe their structure. Graphs G of the first type, corresponding to hinged-lever mechanisms, consist of vertices corresponding to the hinges of the mechanism, and of edges corresponding to its levers. The vertices of graphs 
 of the second type correspond to links of the mechanism, and the edges correspond to kinematic pairs. It turns out that in the absence of combined hinges, the graphs G and @  are equivalent for describing the structure of mechanisms. In the presence of combined hinges, the graph graph @ and the graph 
 obtained by its modification in the theory of mechanisms, in contrast to the graph G, do not provide complete information about the structure of the mechanism.

A posteriori estimates of the parameter of reliability obtained on the basis of the mathematical expectation of the parameter and the variance calculated by the results of a limited number of Bernoulli trials taking into account additional information are examined. The novelty of the results consists in the predictions of the accuracy of the estimation of the parameter of reliability depending on the method of a priori information accounting in addition to a limited number of failure-free tests. The scope of the obtained results includes estimates of the indices of reliability of a highly reliable nonrepairable single-action item based on a small number of tests using a priori information.

To increase the resource and the reliability level, this article considers a radial slide bearing with a metal coating on the shaft surface and the bearing bushing support profile adapted to the friction conditions. We conducted a theoretical study engaging the well-known equations of micropolar fluid motion for a “thin layer,” the equation of continuity, and the equation describing the radius of the molten shaft contour, with account for the formula for the mechanical energy dissipation rate. We obtained an exact automodel and asymptotic solution with and without account for the coating melt, as well as with account for the pressure dependence of viscosity of the lubricant and the coating melt having (both) micropolar rheological properties under laminar flow conditions. Within the experiment, we investigated a modified slide bearing using the modernized model II-5018 friction machine II 5018.

The process of creating 3D models based on the AAA pipeline method is described. It is established that any project or model starts with an idea, which is an interpretation of the customer’s request, which should be provided to clients by meeting the objectives and requirements set for both the whole team and individual developers. An invariant image comparison metric is proposed. The latest development process in the IT sphere, the AAA pipeline, is considered. A step-by-step guide for the AAA pipeline for creating solid 3D objects is presented, including eight basic stages of pipeline execution. Models of a digital concept that provide a comfortable working environment for the design engineer are developed. The created 3D models are exported to another graphics editor.

Mathematical experiments on the study of dynamic thermal processes that occur during the heating of technical devices in the cold are considered. The novelty is in obtaining volume representations of thermal processes occurring in these devices over time: their heating at a lower temperature range limit, using previously accumulated thermal energy in a warm room and increasing it due to additional heating by woven electric heaters when the devices are in a warm room. This article may be of interest to developers of heating systems that use autonomous sources of electricity.