A brief analytical review of existing hydraulic methods and techniques used to remove corrosive deposits formed on metal surfaces is provided. An effective cleaning method is described – hydro-abrasive cleaning (HAC) using bentonite clay, soda ash and polyacrylamide in its composition, which can not only improve the quality of the surface being cleaned, but also form a corrosion-protective film coating on it. The results of experimental research to study the influence of hydro-abrasive cleaning technology parameters on the processed surface of samples made from steels Ст3 (St3), Ст20 (St20) and Ст45 (St45) are presented. It has been shown that changing the parameters of hydro-abrasive cleaning (jet speed, distance to the treated surface, time) makes it possible to achieve a roughness of metal products ranging from 3.2 μm to 12.5 μm. It has been established that the use of a new technology of hydro-abrasive cleaning (HAC) results in the removal of corrosive deposits from metal surfaces with a minimum roughness of up to 0.01 microns. It has also been shown that with a bentonite clay content of 2–4 %, it is possible to achieve surface roughness in the range of 20–30 μm, which is optimal for the flame spraying process. With a bentonite clay content of 0.5–2 %, a surface roughness of 30–50 μm can be achieved, which is optimal for the subsequent painting process. In addition, when carrying out hydro-abrasive cleaning (HAC) on the treated metal surfaces, a long-term anti-corrosion coating is formed, which retains its properties for a long time (up to 1 year).

There is a need in machine-building industries nowadays to automate technologies, in particular, laser ones, to remove surface oxide layers – mill scale, rust – from steel products/pieces in order to improve the energy effectiveness of processing. Herewith, a theoretical assessment method for the intensity of heating of the oxide layer and the phase transition in it can be used to optimize laser cleaning (LC) of the steel surface. To realize this, it is possible to use some calculation and modeling procedures that require, as a first step, the data collection and verification on the temperature-dependent properties of iron-containing condensed phases, as possible components contained, in particular, in scale, which is typically widespread into various metal products. In this regard, the formation of database for characteristics of oxide scale components by the way of selection of information on thermophysical (including optical) properties of the components mentioned and of steel base, which are required for a reliable calculation of the thermal efficiency parameters of the technology for laser cleaning of carbon steels, as well as such actively developed related technologies as laser cutting, drilling, coating remelting, etc., was chosen as the task of our research. An analytical overview of published experimental data made it possible to systematize information on a number of transport and other physical properties of iron-containing components at ambient pressure, including thermal conductivity (k) and diffusivity (a), density ρ, irradiation absorptance and integral emissivity in the temperature range from T ≈ 298 K to the melting temperatures of oxide and metal phases and above them. At the same time, a preliminary thermochemical estimation shows (on the calculated data) the existence of such thermodynamically stable forms of the condensed phase in the heating spot of scale layers during its LC at the melting point and above it, as Fe₃O₄, FeO, and Fe, which is consistent with known experimental data. Comparison of the values of a calculated by us (using the published values of k, ρ and molar heat capacity and using extrapolation in the high-temperature region) for the types of scale components under consideration with a set of experimental values of this parameter in current literature revealed the presence of differences for both oxide and metal phases. These new values make it possible to fill in a gap in the temperature range T = 1600–1800 K that existed in the data on the thermal diffusivity. The value of a = (0.83–0.92)·10^–6 m²/s was also calculated for liquid iron oxide for the T ≈ 1800 K, which was not measured experimentally, that, obviously, prevented modeling of not only laser surface processing, melting and cleaning of steels, but also calculations in the field of metallurgical and other technologies, which are characterized by the presence of iron oxide melts during heating.

The purpose of implants is to replace, restore, maintain or improve the functionality of various tissues and organs of the human body. Their use in modern medicine has significantly improved treatment methods and increased the quality and life expectancy of patients. The most preferable from the point of view of the possibility of imparting the required mechanical properties, the relatively low cost of the material and low production costs are metal implants. Metals and their alloys in the production of implants are superior to ceramic and polymer materials in a range of properties such as tensile strength, endurance limit, wear resistance, hardness, elasticity, viscosity, shape memory effect. The paper provides an overview of the designs of modern implants for various purposes and the metal materials used for their production. An analysis of literature sources has shown that modern implants made of metal materials represent a wide range and have significant differences in shape and size. Some of them are characterized by a small cross-section and rigidity, while possessing elastic properties. Other products are load-bearing, in some cases massive, structures. According to the proposed classification, according to their purpose, metal implants are divided into: dental, cranial, maxillofacial, vertebral, traumatological, cardiovascular and joint endoprostheses. An analysis of the advantages and disadvantages of the main metal materials used in the production of implants (corrosion-resistant steel, titanium and titanium alloys, cobalt-chromium alloys and nitinol) has been performed. It has been established that all currently used biocompatible metal materials are not completely inert towards the body. Each material in any case causes some reaction in the surrounding tissues. The greatest biocompatibility and corrosion resistance in the body is provided by technical titanium, which, however, has low strength characteristics. 

Concrete composites with low defects, dense and homogeneous, with a high degree of adhesion between the cement matrix and aggregates, as well as a high ratio between static tensile and compressive strengths and plasticity have the best crack resistance characteristics. This ratio increases in the case of the use of fiber-reinforced concrete. Modern research in nanotechnology focuses on the management of matter at the nanoscale level, which makes it possible to create materials with new properties. Due to the high aspect ratio, flexibility, high strength and rigidity, carbon nanotubes (CNTs) exhibit reinforcing properties. Due to their nanoscale features, CNTs interact with a complex network of calcium-silicate-hydrate binder (C – S – H), contribute to a decrease in porosity and compaction of the cement stone structure, increase the shear forces of matrix adhesion in the contact zone. Thus, there are all prerequisites to assert that fiber concrete with a cement matrix modified with carbon nanotubes will have the required high strength characteristics and crack resistance due to multilevel dispersed reinforcement and the efficient operation of fiber in a nanomodified concrete matrix. This article presents the results of testing samples made of cement stone, concrete and fiber concrete with carbon nanotubes. The presence of carbon nanotubes in cement stone contributes to an increase in compressive strength by 11 %, tensile strength during bending by 20 %. The test results of samples made of reinforced fiber concrete modified with nanocarbon materials have shown an increase in tensile strength during bending up to 109 %, tensile strength during splitting up to 82 %, axial tensile strength up to 78 %.

This paper discusses examples of the use of local heating systems that improve the comfort conditions of spectators, necessary for a full-fledged perception of events at an indoor ice rink. Indoor ice rinks are popular venues for sporting events, concerts and other entertainment events. However, spectators in the stands of indoor ice rinks during a hockey match or a performance of figure skaters often face the problem of low temperature, which, on the one hand, is necessary to maintain high ice quality, but on the other hand,  can be uncomfortable with prolonged stay of the audience. The paper exa-mines the features of heat and mass transfer processes on indoor ice rinks, including convective and radiation heat exchange with the ice surface and the influence of the configuration of ventilation systems on the air environment inside the arena. The study on the need for mathematical modeling for a deeper understanding of the physical processes occurring inside indoor ice rinks. To study the operation of local heating systems, a numerical solution of a system of differential equations is used that describes the processes of heat and mass transfer in the air space of an indoor ice rink. The paper discusses several technical solutions for the organization of local heating systems. The advantages and disadvantages of the above technical solutions are highlighted. A comprehensive analysis of the operation of local heating systems at an indoor ice rink is an important contribution to the understanding the physical processes and parameters that affect the microclimate inside indoor ice rinks, and can also serve as the basis for optimizing such systems in order to ensure comfortable conditions for spectators.

high strength and stability of asphalt concrete, but also at ensuring optimal characteristics of its structure.

The main principles for the optimization of the grain composition are based on the parameters of the size and shape of thе stone aggregate particles included in the composition of asphalt concrete mixtures. An in-depth analysis of the grain composition helps to achieve an optimal balance between coarse and fine fractions, which in turn ensures the stability and durability of the asphalt concrete pavement. The maximum density of an asphalt concrete mixture  plays a key role, influen-cing its physical and mechanical properties and ability to withstand aggressive environmental influences and traffic loads. In addition, the density of the mixture significantly affects its resistance to static and dynamic loads  and deformations, which is important for ensuring road safety. The paper provides an analytical review of the basic principles and methodology for determining the grain composition of fine-grained asphaltic concrete mixtures with grain sizes up to 10 mm in order to achieve their maximum density. Both domestic and foreign methods for optimizing mixture design parameters are considered. Based on the consideration of ideal mathematical curves the grain composition, the main regularity for fine-grained asphalt concrete has been established, which has similar parameters to the mathematical Fourier curve. Understanding and practical application of the principles of constructing the grain composition of asphalt concrete mixtures of maximum density not only improves the quality of road construction, but also contributes to a more efficient use of resources, ensuring the stability and durability of the pavement. This leads to a reduction in road maintenance and repair costs, which is an important  aspect in the context of the economic efficiency of infrastructure projects. Thus, improving the methods for investigating and controlling the grain composition of asphalt concrete is important for the sustainable development of road construction.

The main criterion for a feasibility study of the production efficiency of precast construction plants, analysis of internal production reserves and optimal production volume is the production capacity indicator. Thus, the study of various Factors influencing the production capacity indicators is an important task. The results of research of the influence of the number of storeys and the set of block sections in the configuration of industrial residential buildings on changes in the ratio of product types in the range of the production programme of plants are presented in the paper. Fluctuations in the ratio of product types during the construction of different types of houses have been established.  Based on the obtained results, the dependence of the production capacity plants on fluctuations in the ratio of product types has been constructed. It has been determined that the main reason for the revealed facts of a decrease in production capacity is the uneven loading of production lines with fluctuations in the ratio of product types in the range of production programs of precast construction plants. Taking into account the known facts of  the dependence of production capacity on the concrete capacity of block sections of houses, the results of a comparison of the degree of influence of concrete capacity on the production capacity and the ratio of the main types of products in the range of production programs of plants are presented in the paper. It has been established that a key influence on the indicators of production capacity is exerted by  changes in the ratio of product types. On the basis of the conducted research, optimal reserves of production capacity have been determined with a high share of different types of houses in the production programs of the plants. Taking into account the established indicators of production capacity reduction, their optimal reservation is within 20–25 % of the design capacity of the plants, which should serve as a reference point when planning the functioning of the production management system under the conditions of changes in demand for products.

The paper proposes an original design of a continuously variable two-flow hydrostatic-mechanical transmission, which ensures division of the power flow along the sides of the crawler tractor. To ensure stability of rectilinear motion, their volumetric and mechanical efficiency, the maximum pressure of the working fluid in the hydraulic transmission, the maximum speed and torque on the shaft of the hydraulic motor. The parameters of an unregulated hydraulic motor, an adjust-table pump and mechanical transmission elements are selected. A mathematical model of the rectilinear motion of a caterpillar tractor with a continuously variable hydrostatic-mechanical transmission has been developed, taking into account the weight of the tractor, the parameters of the running system, the characteristics of the internal combustion engine, the parameters and efficiency of hydraulic machines, gearboxes, range and transfer boxes, planetary gear and allowing to determine the efficiency of individual branches and the entire transmission, carry out traction calculations of the tractor. A calculation program has been developed that implements the mathematical model. The parameters of the dual-flow transmission are selected so that most of the torque is transmitted through the mechanical branch and the transmission has a fairly high efficiency value. The maximum value of tractor traction efficiency is realized in the second and third ranges, which are designed to perform basic tillage operations.

. Transport enterprises of the Republic of Belarus today are at the stage of overcoming the consequences of the COVID-19 pandemic and sanctions pressure related to the peculiarities of the development of its economy. Modern operating cоnditions for enterprises providing passenger transportation services dictate that service providers focus on structural and organizational development, and on increasing efficiency in meeting the changing demands of consumers. Achieving an economic result for this type of enterprise is equivalent to determining a rational ratio of costs for  production, material, financial and labor resources in the process of providing transport services. The processes of agglomeration of passenger transportation in suburban traffic, urbanization, as well as the emergence of technologically new means of personal mobility have intensified restructuring of passenger flows in public transport services. In suburban and urban passenger transportation, road and rail transport is most often involved, and  inland water transport is less common. Passenger transportation is carried out by various types of ground transport: buses and electric buses, trolleybuses and trams, taxi cars and also transport owned by citizens, the competition between which depends on the ratio of price parities of a carrier and the level of consumer income. In this regard, it is necessary to revise price and non-price measures of flexible response of transport carriers of passengers in the process of providing socially significant services. This paper examines the essence of services for the transportation of passengers in regular traffic within the boundaries of the territory of Minsk in relation to the current level of development of the transport and logistics system of the Republic of Belarus. The purpose of the study was to develop proposals for calculating the cost of transport work for passenger transportation using the example of the electric transport fleet in Minsk.