The third potash seam of the Starobinsky deposit is mainly mined using the layered mining technology. The essence of the technology lies in the advance excavation of the 4^th sylvinite layer by the uppere lava and the joint excavation of  layers 2, 2–3 and 3 by the lagging lower lava under the protection of the interlayer pack of rock salt 3–4 (ceiling) left in the goaf. The thickness of the ceiling in accordance with the requirements of the regulatory document should be at least 0.8 m. At the same time, in the mine field of the mine of the Third Mine Administration, there are areas with a ceiling thickness reduced to 0.66–0.70 m. The purpose of the author’s research was to determine the possibility of safe mining of the Third potash seam using the layered mining technology with a reduced thickness of the ceiling. In the course of a full-scale experiment, the geological structure and strength properties of the rocks of the ceiling, its stability in the bottomhole space and the intensity of loading of the bottomhole lining of the lower lavas have been studied in the paper. The research methods also included the analysis of literary sources and statistical processing of the obtained data. It has been established  that a decrease in the thickness of the ceiling by 0.10–0.14 m from the required one does not have a significant effect on its strength, while it remains stable in the near-bottom space of the lower longwalls. The main indicators of the manifestation of rock pressure in the studied lower longwalls – the rate of increase of the bottomhole lining in the stope cycles and the lowering of the roof in the bottomhole space – did not exceed the similar indicators in the longwalls with the required thickness of the ceiling.  The obtained data indicate the possibility of safemining of the Third potash seam using the layered excavation technology with the thickness of the interlayer rock salt pack 3–4 not less than 0.66 m. In this case, the bearing capacity of the bottomhole lining should be at least 550 kN/m².   

The features of the formation of castings from chromium cast iron during casting in a combined mold are studied using internal sources of heat removal introduced into the melt. A series of experiemеnts has been carried out with wear-resistant chromium cast iron. The following macrocoolers have been used: a 0.5 mm thick silumin plate containing 3–5 % Ti; a mixture of borax and crushed ferrochrome (1–4 mm); white cast iron shot. The phase composition of the samples has been determined by X-ray diffraction analysis, and their microstructure has been also studied. Hardness testing has been carried out on specimens obtained with cast iron shot. The most effective method of using an internal source of heat removal, which has a significant effect on the cooling rate of the casting and its microstructure, has been determined. The most promising was a mixture of borax and crushed ferrochrome particles, which did not dissolve in the melt and formed zones with local structure refinement, as well as white cast iron shot, a more technological alternative to ferrochrome. The use of white cast iron shot has led to a refinement of the structure of the part “Backing sheet У3.1,1 [U3.1.1]” made of wear-resistant chromium cast iron, as well as to an increase in the hardness of its working surface by 2.6 HRC. Almost all of the shot introduced into the melt has been melted. As a result of the research, it has been revealed that the use of ferrochrome and white cast iron shot is an effective way of local structure refinement and a practical possibility of obtaining a part made of chromium cast iron with increased hardness. All this can increase the wear resistance of parts of crushing and grinding equipment.

The paper proposes a set of technical tools for solving the problem of ensuring the uniformity of measurements of micro- and nanoparticles. To do this, it is necessary to ensure the traceabilityof particle size measurements to a unit of length – 
a meter, as well as equivalent diameters used in measurements in various dispersed media (aerosols and suspensions). To ensure traceability of particle diameter measurements to the meter, it is proposed to use a nanomeasuring machine with an atomic force microscope as a probing system. The paper presents a diagram of the measuring system, describes the principle of operation of the machine and the method for measuring particle sizes. The main alleged sources of errors in particle measurement by this method are also identified. To ensure the traceability of measurements of the hydrodynamic diameter of nanoparticles, which characterizes particles in a liquid (suspension), it is proposed to use a nanoparticle size analyzer that implements the method of dynamic light scattering. The scheme of the analyzer with a description of the principle of measuring the size of nanoparticles by the method of dynamic light scattering is presented in the paper. The scheme of the column of the analyzer of the differential electrical mobility of particles is presented to ensure the traceability of measurements of their diameter, which is equivalent in electrical mobility. Diameter is usually used to characterize particles in the aerosol state. A diagram of an analyzer for the differential electric mobility of particles is given with a description of the operating principle, a formula for calculating the particle diameter is derived.

Reservoirs with multifunctional purposes are the most widely used as sources of water for irrigation. In China, a large number of irrigation systems have been created using reservoirs as sources for flood prevention, irrigation, industrial and agricultural water supply. In Belarus, the Soligorsk, Lyuban, Petrovich, Pogost and other multifunctional reservoirs are 

used for irrigation.  The useful (regulating) volume of a multifunctional reservoir consists of separate components calculated for each consumer in the basis of a hydrological and feasibility study. Thus, the useful volume of water intended for irrigation should provide the required irrigation capacity and capacity of the irrigation system. When determining the useful (regulating) volume of a multifunctional reservoir, the total water requirements for various purposes (water supply, irrigation, hydropower, etc.) are calculated. For each consumer, the required design supply is assigned and the appropriate method for determining water consumption is used.  Reservoirs intended for water supply count on 95–97 % availability of runoff, and for irrigation purposes – on 75–80 % availability in zones of moderate and excessive moisture. In arid, desert and semi-desert regions of China, where lack of water in dry years can lead to large crop losses, irrigation reservoirs are expected to be 90–95 % secure. The volumes and costs of water in the reservoir for irrigation purposes must cover the needs of plants in water within the established time frame for the year of estimated availability. The paper provides a formula for determining the weighted average irrigation rate and the volume of water required for irrigation. A methodology is presented for calculating the useful volume of a reservoir intended for industrial water supply and irrigation, for which flow regulation is calculated for two supply of water consumption. A method is proposed for determining the flow rate of entrained sediments for various stages of their movement. A formula is presented for the total volume of suspended and bottom sediments entering the reservoir.

The experience of developed countries shows that the development of the road network and transport infrastructure determines the intensity of economic ties and is one of the most important conditions for the development of the state’s economy. Optimization of the composition and production technology of asphalt concrete mixture – the basis of paved roads, is of great importance, both from an economic and environmental point of view. The production of asphalt concrete mixture directly (during the production process at asphalt concrete plants) and indirectly (during delivery from the plant to the place of installation) determines the energy costs for the production of asphalt concrete. At asphalt-concrete plants the specific energy consumption per ton of hot asphalt concrete mixture varies from 0.3 to 0.7 GJ. The range in energy costs is large. This situation indicates the presence of a significant energy-saving potential of asphalt concrete mixture thermal technology. The exergy analysis of technical systems proposed in this paper, which are operated in the asphalt concrete mixture production processes, makes it possible to judge the efficiency of energy use in their thermal units. This approach is expedient not only in the primary production of asphalt concrete mixture, but also for more environmentally friendly, energy- and resource-saving production processes for the operation of equipment during the regeneration of road asphalt concrete.

Concrete is a quasi-brittle building material that has low tensile strength. The process of its destruction under loading is inhomogeneous, due to the nature of the concrete structure mass, consisting of components with different physical and mechanical properties. Gradual deformation and destruction can be characterized as a process of formation and development of microcracks. The presence of different-sized components in concrete makes it possible to consider its structure as a multi-level system. In this system, each level is a matrix with its own structural inclusions, which play both a structure-forming role and the role of stress concentrators under the action of mechanical loads. The critical stress intensity factor is a good indicator of the crack resistance (fracture toughness) of a material. Nanoconcrete, from the point of view of a multilevel system, is a concrete composite with crack propagation inhibitors at the level of the cementing substance (carbon nanotubes are consi-dered as inhibitors). The presence of fiber fibers at subsequent scale levels allows us to consider concrete as a composite with multi-level dispersed reinforcement (nanofiber concrete). The paper discusses the change of concrete fracture toughness indicator (crack resistance) with dispersed reinforcement of the matrix at different structural levels. The 

presented for normal separation of notched cubes under eccentric compression with the determination of the stress intensity factor for concrete modified with carbon nanotubes acting as crack propagation inhibitors at the level of cementing substance (nanoconcrete), as well as for nanofiber concrete with dispersed reinforcement at the level of fine-grained concrete. Based on experimental studies by non-equilibrium methods of fracture mechanics, compositions of nanofiber-reinforced concrete of maximum crack resistance (fracture toughness) with different fiber concentrations and several types of matrices modified with nanocarbon additives are proposed in the paper.

Road bases are the main bearing layers of the road pavement, the purpose of which is the perception of the load from cars and its distribution on the subgrade soil. The base structure is determined by calculation depending on the planned traffic load and traffic intensity and usually consists of two layers, and for capital coatings, the upper layer of the two-layer base is made of materials reinforced with binders. The base of the pavement is a rather expensive construction and it is important for its construction, where possible, to use local materials, as well as secondary materials, i. e. industrial and construction industry waste.  In the process of construction and repair works, the use of secondary raw materials can significantly reduce the cost of their implementation. Moreover, this practice not only reduces the cost of work, but also reduces the negative impact on the environment. The paper considers the possibility of constructing a pavement base from such secondary materials as spent molding sands (foundry waste), cement granulate (a product of crushing old cement concrete structures, construction waste) and asphalt granulate (a product of milling worn asphalt concrete pavements). In this case, the cost of the base is significantly reduced  while еnsuring its necessary strength. Spent sands were used as a leveling layer, cement granulate

Field studies of panel buildings have shown that after 30 years of operation, the technical condition of structural elements (embedded parts, welds, etc.) are in working condition. At the same time, the thermal characteristics of the external wall fencing have decreased by more than 30 % compared to those adopted during the design and do not meet regulatory requirements. One of the main reasons for this is the destruction of the material of the thermal insulation layer of wall panels under the influence of atmospheric influences. Consequently, the thermal rehabilitation of external wall panels allows for  further operation of panel buildings without restrictions. According to the results of the studies carried out, it is proposed to use a factory-made thermal insulation cladding plate for thermal rehabilitation of the facades of operated panel buildings. The publication presents the results of laboratory studies on the choice of an effective solution for the design of the conection (joint) of individual thermal insulation plate into a thermal insulation facing plate of the required dimensions. The technology of manufacturing thermal insulation facing plates is described. The main advantages of the proposed structural 

and technological solution for the thermal rehabilitation of external wall panels are: a significant reduction in manual technological processes on the construction site; the possibility of performing work without eviction of residents; eliminating the appearance of cold bridges in the inter-panel seams during the operation of buildings through the use of a folding type joint.

The paper presents the methodological provisions for the organization of logistics operations during the transportation of household electronic waste in large cities. Human activity is accompanied by the formation of waste, the amount of which has recently increased. In modern conditions, households actively use electronic and electrical devices. Therefore, a lot of household electronic and electrical waste is generated, which is hazardous to the environment and must be disposed of in accordance with legal requirements. The efficiency of disposal of household electronic waste depends on the organization of logistics operations for the collection, accumulation and removal of such waste. The main methodological stages of logistical support for the recycling process include the formation of a hierarchy of territorial formations (taxons), standardization of waste generation indicators for taxa of each level in the hierarchy, designing the configuration of a network of collection points for acceptance and temporary storage of waste within the boundaries of the service area, substantiating the rational storage capacity of each point and deadlines for waste storage; planning the transportation of waste from accumulation points to objects of their further processing. When planning the transportation of waste, the actual volume of waste accumulation at each collection point is taken into account, transportation routes are designed for the shortest distances, taking into account the capacity of vehicles. The main feature of the developed method of waste removal is the operational adjustment of routes so that the car drives only to those accumulation points where the actual volume of waste has reached the maximum storage capacity. This approach ensures timely waste collection and lower transportation costs compared to existing methods that organize waste collection at a specified frequency. The developed methodology was tested on the basis of statistical data from Hanoi (Vietnam). The results of numerical experiments show that the application of methods provides a reduction in transport costs for the removal of household electronic waste, and also increases the level of their collection and disposal.

In the conditions of necessity of transition to Industry 4.0 the human resource potential is considered as an important source of competitive advantage.  Only qualified personnel can make an organization competitive on the basis of market loyalty, product and service quality, differentiated products and technological innovation. Two directions for increasing the competitiveness of industrial enterprises have been identified. The first is the assessment of the system of indicators of human resource level during the transition to Industry 4.0. The second is to identify the most significant factors in assessing the level of human resources that affect the increase in the level of competitiveness of industrial organizations. The paper provides a detailed analysis of a number of economic indicators that characterize the integral indicator of the effectiveness of the human resources development and competitiveness of an industrial organization. The integral indicator has formed the basis of a model for assessing the competitiveness of industrial organizations through human resource development. The model consists of two parts: human resource development and the increase in the level of competitiveness of industrial organizations. The model is based on the following factors: the quality of human resources (staff composition of an industrial organization, the number of employees, their income level, education level, projects related to human resource development) and its development (total corporate income, share employee remuneration in the total organization income, R&D costs, the share of investment in R&D in the total organization income, sales and production). The developed model will allow organizations to adjust their human resource development strategies (recruitment and further development of human resources), and will also contribute to the transformation of corporate talent.