This article contains the results of a study of the strength characteristics of building mortars of various compositions based on magnesia binder (magnesia oxychloride cement). The results obtained: the final compressive strength (28-day) within the studied compositions is from 12 to 45 MPa, the kinetics (rate) of strength growth on the first day of hardening is from 22 to 38%, on the third day of hardening – 33-68%, on the seventh day – from 50-88%, and about 120% from the design (28-day) with further hardening.

Keywords: magnesia oxychloride cement, magnesia binder, magnesia mortar, magnesia concrete, caustic magnesite, magnesium chloride, compressive strength, strength set kinetics

When clearing territories for the construction and / or subsequent maintenance of such infrastructure facilities as construction sites, airfield territories, right-of-way for roads and railways, heat supply routes, and so on, work is often carried out to remove growing undesirable tree and shrub vegetation, At the same time, the problem of assessing the quality of the performance of these works is relevant. The authors of the article consider the issues of mathematical modeling for assessing the quality and effectiveness of the work performed to clear the territories of a number of the above infrastructure facilities, give the boundary values ​​of the criteria for assessing the quality of the measures taken to remove vegetation, and formulate a conclusion about the advantages of the developed mathematical model.

Keywords: territory, unwanted vegetation, removal, efficiency, quality, criteria, evaluation

The paper studies the problems of heat transfer intensification in shell-and-tube heat exchangers used in the heat supply of buildings. The solution to this problem is to use the circulation of the coolant flow in a pulsed mode, with different frequency pulsations. Based on experimental studies to determine the efficiency of a shell-and-tube water-to-water heat exchanger, a method has been proposed, in accordance with which it has been proved that the pulsed mode, compared to the stationary one, is the most effective in terms of key indicators, such as the heat transfer coefficient and thermal power.

Keywords: intensification, heat transfer, heat exchanger, coolant, fluctuations, efficiency, thermal power

The article studies the thermal conditions in the heating system of a two-storey building of the laboratory building of the Medical Institute. The analysis was carried out on the basis of data obtained from thermograms of heating devices. The study of thermal conditions in a two-pipe heating system is carried out, the actual and estimated power of each heating device is determined, as well as the temperature inside the premises.

Keywords: Coolant regulation, heating system, thermostat, thermal modes, thermogram, coolant, balancing, heating system

The support in the bottom-hole zone of the trunk is a system of rings made of monolithic concrete having a different hardening period, which increases from the face up the trunk and is determined by the duration of the tunneling cycle. The strength and deformation parameters of the concrete support depend on the age of the concrete. Thus, to determine the strength of concrete in the early stages of concrete hardening, various empirical dependencies are used that link the strength of concrete at the design age with the strength at the required age. Based on a series of calculations performed by the finite element method, it was found that the change in the penetration rate does not significantly affect the relationship between stresses and deformations when static equilibrium is reached in the ""support – array"" system, which occurs at a high penetration rate at a greater distance from the bottom of the trunk. At the same time, intensive loading of the support at an early age can disrupt the process of natural hardening of concrete, lead to a violation of its structure, the development of fracturing, which will entail a decrease in the bearing capacity and water resistance of the support, a decrease in its durability.

Keywords: shaft, sinking, support, concrete, stress, deformation, strength, bearing capacity

The article discusses the importance of using energy-saving and energy-efficient technologies for the purpose of sustainable development of the country's territory. Examples of the introduction of energy-efficient residential complexes in Europe, as well as the experience of using these technologies in Russia are presented.

Keywords: energy efficiency, energy-saving technologies, construction, world experience, energy saving

Natural disasters can cause serious damage to cities and entire regions, which makes it important to improve the efficiency of planning repair and construction work when restoring built-up areas. The article discusses the organizational and managerial aspects of the restoration of territories affected by natural disasters, which is the basis for effective planning and implementation of projects for the reconstruction and restoration of settlements.

Keywords: natural disasters, emergency situation, urban area, advanced planning, infrastructure

This article attempts to consider some of the features of the calculation and operation of light trusses from rolling corners. Is given brief information about the history of the use of trusses from single corners, their advantages and some disadvantages, as well as the prospects for the use of structures of this type in modern construction practice. Based on the analysis of the design documentation for a number of industrial facilities built over the past two decades in the Khabarovsk Territory, are analyzed the most common mistakes that designers make when developing roof structures using trusses from single rolling angles.

Keywords: farm from single rolling corners; corrosion resistance of elements; eccentricity of the acting effort; loading nodal moment; the value of the coefficient of working conditions; farm support node; additional forces in compressed rods

Studies of building control issues are one of the most topical for industries and human life. The construction industry is one of those. The problem of safe and high-quality unique buildings is closely related to quality construction control.The article discusses the main stages of the documents regulating construction control in the implementation of unique objects, their systematization is given. The schemes of interaction of the main construction participants at the stage of construction and installation works with the obligatory involvement of experts in scientific and technical support of construction for the purpose of further study are presented.

Keywords: construction control, unique buildings, scientific and technical support of construction, construction quality, Camunda BPM

In this paper, a study was made of the test device for voltage stabilizers Teplocom ST-222/500, ST-555, ST-888. The DUT provides the verification algorithm outlined in the setup, verification, and process run instructions. This test involves changing the phasing of the conductors at the input of the device under test; control of voltage sources supplied to the tested stabilizer; measurement of voltage values ​​at the input and output of the stabilizer; their registration. The aim of the work is to design a device for testing voltage stabilizers, with an error of the measuring unit of not more than 2.5% and a test speed of at least 1.3 s. To confirm the achievement of the specified parameters, simulation was carried out in the MicroCap 11 software package.

Keywords: voltage stabilizer, MicroCap, Teplocom, transient simulation

This article discusses the advantages and perspective for the use of biogas in the conditions of the Republic of Crimea. The ecological and economic aspects of the use of biogas technologies at winemaking enterprises are touched upon. Describes the methods of using biogas at the winery "Massandra" in the Republic of Crimea. The calculation of the use of natural gas in the boiler house of a winery is made. A calculation was made for the use of biogas in a boiler house. It can be concluded that when using biogas in the boiler house of a winery, fuel needs are fully covered. The surplus of the remaining fuel is proposed to be used in a cogeneration plant to generate electricity.

Keywords: biogas, cogeneration plant, grape plant residue, recycling, interchangeability, granulate, natural gas, grapes, thermal energy, electricity, winery

The article considers one of the ways to improve the reliability of mining equipment, by eliminating sudden failures and reducing the severity of their consequences, based on the use of digital technologies and automated control systems for its technical condition and online diagnostics. It is proposed to use the methods of diagnostics and automated control of the technical condition of power electrical machines, which consist in monitoring the current with subsequent spectral analysis of the recorded signal. The method allows to determine the current technical condition of the engine elements with sufficient accuracy. A high-performance RISC microcontroller of the AVR ATmega16 family was adopted as the constituent elements of the diagnostic complex, which contains a fast Harvard processor, program memory, data memory, input / output ports and various interface circuits.

Keywords: reliability of mining equipment, diagnostics, automated control, current monitoring, spectral analysis

As part of the proper maintenance of a number of infrastructure facilities (right-of-way for roads and railways, protected zones of power lines, gas pipeline routes, etc.), work is being carried out on their territory to remove growing unwanted vegetation. The article discusses the features of determining the values ​​of capital investments for the formation of a system of machines, mechanisms and used mechanized and manual equipment for cleaning these territories from unwanted vegetation, shows an example of their calculation using specific brands of machines, mechanisms and equipment used in production, formulates a conclusion about the feasibility of introducing of the considered method into the production process of enterprises and organizations responsible for the maintenance of the indicated territories of linear infrastructure facilities.

Keywords: territory, unwanted vegetation, removal, mechanization, equipment, definition, capital investment

The article presents the results of checking the adequacy of the method of online diagnostics and automated control of the technical condition of the electromechanical drive of the KP21 mining machine with an asynchronous squirrel-cage motor, proposed earlier by the authors. The method of experimental production studies provides for the connection of the measuring complex to the stator winding of one of the phases of the electric motor. The measurements were carried out under various operating conditions of the combine, corresponding to various technical conditions of the facility. A comparative analysis of the technical condition of the diagnosed nodes and the values ​​of the normalized amplitudes of the corresponding frequencies led to the conclusion: the defect must be fixed if the signal amplitude exceeds the value of 10% of the maximum, and the defect is significant and needs to be eliminated if the amplitude value exceeds 30%. To use the obtained research results in practice, an integral nomogram of the correspondence between the operating time of the combine harvester and the amplitude - frequency characteristic of the stator current of the drive motor of the cutting body is proposed. The results obtained are taken as a basis for correcting the schedule of preventive maintenance and maintenance of the cutting body of mining machines KP21 when operating in the appropriate mining and geological conditions.

Keywords: reliability of mining equipment, online diagnostics, automated control, current monitoring, maintenance and repair

This article gives an overview of the operation of dehumidification plants located in indoor ice arenas. Since at the moment the operation of such facilities does not include control of such parameters as CO2 content, the possibility of implementing this task using the existing equipment is considered. A method of setting the automatics of maintaining the CO2 level in the set parameters is given. The principle of dehumidifier operation and problems of CO2 level control are considered. The method of tuning the control loops is also described. The use of CO2 controlled dehumidifier equipment will create comfortable conditions for the occupants of the ice arena, which in turn will lead to a reduction in energy and heat consumption.

Keywords: automatic control system, control loop, control object, process stabilisation, air drying, air drying plant