The construction of public buildings from a metal frame is always associated with the search for a rational constructive solution that meets not only the dependability requirements, safety, but also architectural and design solutions. Often, the solution to the problem of rationalization of roof construction in public buildings is the use of arched combined systems, since such systems have a number of advantages over simple arches: the survivability of combined systems is higher than simple ones, the possibility of creating complex, architecturally expressive spatial structures, lower material consumption, high load-carrying ability with relatively low weight, etc. The aim of the research is to find a rational construction solution for two arch-cable systems (Hud type system and Radial type system) by comparing in terms of the minimum internal forces, displacements and metal intensity at different ratios of the arch boom and span. Based on the calculation results in the Lira SAPR 2020 software, the most unfavorable loads combinations were determined, deformation schemes of arch systems, displacements, moments and forces were obtained, sections of arches and ties were selected. From ten arched structures of two types considered with different ratios of arch boom to span, the Hub type system with the ratio of arch boom to span f/L = 1/3 and Radial type system with the ratio of boom to span f/L = 1/4 showed the best result in terms of efficient operation and metal intensity.

Keywords: combined systems, arch-cable constructions, simulation of prestress, hub type s

The article considers the relevance of the use of nanomodified concrete in construction. The compositions of the studied mixtures are given, as well as the methods of their preparation using ultrasonic dispersion, the results of the experiment on the destructive effect of standard samples of beams are obtained. The conclusions of the obtained experimental data are presented.

Keywords: concrete, foam concrete, carbon nanotubes, superplasticizer, dispersion

The problem of removal of combustion products during the reconstruction of existing boiler houses is considered. The issue of determining pressure losses due to friction in steel and brick gas ducts when performing an aerodynamic calculation of gas ducts from gas-fired boilers is considered. Nomograms have been developed that make it possible to determine the specific pressure loss depending on the volume of flue gases and the diameter of the gas ducts.

Keywords: reconstruction, boiler units, aerodynamic calculation, friction pressure losses, gas ducts

To improve the quality of bearing rings, modern production strives to apply new modern methods for detecting defects based on the causes of their occurrence, as well as to introduce quality control systems by creating specialized software. An accurate assessment of the dynamic properties of bearings is very important for machines and helps to avoid serious mechanical damage. As part of the experiments, the main control methods were considered and the most effective one was established - eddy current control, which has a number of advantages compared to others. To prevent the occurrence of defective products in the control system, the fractal dimension method was considered and a neural network was built to solve the tasks of diagnosing.

Keywords: defect diagnosis, bearings, neural networks, automated control, fractal dimension, SVD filtering, Matlab software, monitoring system.

The author carried out the development of the measuring unit of the intellectual system for the protection of the territory. Based on the review of devices of a similar purpose, a block diagram of the device was developed. A functional diagram of the developed device based on the block diagram has been developed and described. The description of the computer experiment on modeling the operation of the input block of the circuit in Micro-Cap, its results and analysis is given.

Keywords: measuring unit, intelligent system, modeling, vibration, triboelectric sensor

The article examines the modern protection of the population of dual-use facilities, an analysis of it's effectiveness and further protects for the development of solving this problems. Yhe analysis was performed on the example of comparing the provision of the population with buried and other underground spaces in federal districts.

Keywords: protection of the population, infrastructure composition, types of protection, main activities, security of the population, garrison

The sedimentation analysis method is based on the measurement of the deposition rate of suspended solids depending on their equivalent diameter. The use of sedimentation for disperse systems is limited by their size, as microscopic dust particles have low deposition rates and are difficult to analyze. Therefore, for finely dispersed systems, the authors propose a method of sedimentation analysis using portable cameras that record the deposition process and break it down into frames. The images obtained frame by frame are translated with the help of a graphic editor into binary (black and white) format, which is able to process the software. The experimental data obtained are presented in the form of tables and distribution functions.

Keywords: sedimentation, dispersion, dust, binary photography, equivalent diameter, cement dust, distribution function

The effect of a zeolite support on the physicochemical properties of cobalt catalysts prepared by the precipitation method and calcined at 400°C was studied. The values of the specific surface of the catalysts, the degree of cobalt reduction, and the dispersion of the metal were determined, and the presence of functional groups on the surface of the catalysts was determined by BET, TPV, TPD-H2, and IR spectroscopy.

Keywords: catalyst, cobalt oxide, hydrocarbons, dispersion, active surface

When performing work on the inspection of residential buildings for deconservation, there are often problems associated with determining the composition of work, as well as problems related to the organization of work. This article discusses the scope of work on the survey of residential buildings for deconservation, as well as presents work in the form of schedules that allow you to predict the timing of work, as well as coordinate the exit of specialists to the facility.

Keywords: inspection of buildings, conservation of the object, organization of work, schedule of work, construction in progress, scope of work

Since the volume of restoration works of cultural heritage objects has been increasing recently, cases of problems related to the survey of these objects are not uncommon.this article discusses the main problems that arise during the survey of buildings and structures related to cultural heritage objects and suggests possible ways to solve them.

Keywords: inspection of buildings, object of cultural heritage, organization of work, non-destructive methods for determining the strength of concrete

The article deals with the issue of the influence of ambient temperature on the initial height of the flare emissions rise. The paper presents full-scale and theoretical studies of flare emissions operating near a temporary residential complex. In the course of the work, a series of images of flare emissions at different ambient temperature conditions was carried out and their subsequent comparison with the theoretical model was carried out. Field studies verify the theoretical model and establish that the initial height of the flare emissions depends on the ambient temperature and has an inverse proportionality.

Keywords: Flare, flare emissions, atmospheric air pollution, PM2.5

Engineering and geological conditions of the reconstructed territories are important town-regulating factors in the development of Master Plans and Rules of land use and development. They should be taken into account both at the pre-investment stage and at the stages of development of preliminary and working projects of construction projects. Data on the degree of exposure to dangerous engineering and geological processes will allow calculating the stress-strain state of the foundation depending on changes in the physical and mechanical properties of the soil, which means making the most effective organizational and technological decisions for the reconstruction of urban development.

Keywords: engineering and geological surveys, dense urban development, reconstructed territories, geoinformation bases, digital substructure, geological risks

The article considers the directions of development of energy, transport and water facilities through the use of liquefied natural gas.

Keywords: liquefied natural gas, energy, methane, motor transport

To ensure the correct and continuous operation of all electronic devices, it is necessary that all components of these devices correspond to their declared characteristics. In this article, an information-measuring system for incoming control and analysis of the quality of components is being developed. Structural and functional diagrams of the system were developed. A natural experiment was carried out.

Keywords: information-measuring system, input control, quality analysis, components

The electrophysical and mechanical properties of a piezoceramic material based on CTS are investigated. A number of features in the behavior of the electrophysical properties of the material in the temperature range located significantly below the low-frequency (1 kHz) maximum of the dielectric constant T_m = 160℃ have been revealed. The obtained results indicate the proximity of the studied material to ferroelectric relaxors, in particular, the low coercive field E_c~5 kVcmcm, the significant dependence of T_m on the frequency and amplitude of the measuring field, as well as the behavior of the velocity of longitudinal ultrasonic waves in this ceramic. It is shown that the elastic properties of this material are very close to ferroelectric relaxors, having a high malleability in a very wide temperature range. At the same time, the squareness of the polarization loops at relatively low temperatures indicates the manifestation of the classical properties of the ferroelectric during the polarization switching processes, and not the "freezing" processes characteristic of ferroelectric relaxors. From the results obtained, it can be established that this composition will be promising for use in the actuators of adaptive optics systems and precision positioning devices due to the high values of piezomodules.

Keywords: PZT system, ferroalloy ceramics, dispersion, polarization, elastic properties, blurred phase transitions, curie temperature, depolarization temperature, ferroelectric relaxor, rhombohedral phase, tetragonal phase