The article describes the concept of the digital gas sensors for toxic and flammable gases used in portable gas analyzers and stationary systems for dangerous objects monitoring. The results of the development of the low-power digital gas sensor for determining the concentration of carbon monoxide are described. The structure of the analog sensitive element, as well as its sensitivity to various gases and ambient temperature, is considered. A structural and schematic solution of a digital gas sensor using operational amplifiers and a miniature microcontroller is presented. The algorithm of firmware of the microcontroller is considered, as well as the calibration process.

Keywords: Digital gas sensor, toxic gas, gas converter, carbon monoxide, gas analyzer, monitoring system, calibration process, gas generator

Beams are structural elements subjected to bending loads transverse to their longitudinal axis. For steel beams, which compressed flange is not laterally restrained, checking loss of overall stability is often authoritative in determining their section. In engineering practice are known various approaches to verify the assurance of the steel beam against lateral-torsional buckling. In this article the attention is focused to the methods and their characteristics, described in actual version of the European standard EN1993-1-1.

Keywords: lateral-torsional buckling, steel beams, critical bending force, FEA

Radon is universally present in the atmosphere and is the most important natural source of radiation. The highest radon doses relate to staying in buildings. However, the damage from radiation exposure to radon is associated with the progression of lung cancer and the premature death from this disease of people exposed to radiation. The application of the principle of optimization of radiation protection in a radon exposure situation is complicated by the fact that a number of tasks remain ignored.

Keywords: Radon, territory, gas, radiation, emitting, dose, volumetric activity, source, site, protection, premises

The article is devoted to the approach to the development and design of effective dust collectors for the aspiration systems of the construction industry. It was proposed and implemented the study of the particle shape factors that determine the hydrodynamic features of gas flow around dust particles, for example, in the aspiration schemes, which are most spread and applied in the construction industry using the results of complex analysis of variance it this article. It was presented results of implementation hydrodynamic criteria in the output function of the analysis. The values’ meanings of the particle shape factors of the dusts’ particles were gained and obtained at the final stage of experiment. It was obtained regressions for particle shape factors as functions of hydrodynamic criteria. It was proposed dependences to clarify the particle sedimentation-growth velocities taking into account the influence of the particle shape factors of the studied dust samples. It was allowed possibility to assess and obtain ranges of changes in the values’ meanings of particle shape factors. It was obtained more reliable results for determining the sedimentation values’ velocities of dust particle as a determining result of complex analysis of variance of particles also. The research results allow the development and design of dust collecting devices for cleaning emissions in dust removal systems of the aspiration schemes of the construction industry. These dust kinds of collector provides a significant reduction in dust leakage out from dust removal systems of the aspiration. This way become one of the highly effective prevents polluting ways that allows to improve environmental safety of the construction industry.

Keywords: Dust, building material, dust collector, cleaning, leakage, analysis of variance, velocity, sedimentation, criterion, emission, atmosphere, dust removal, aspiration

In the article, a numerical study of the heat sink with a change in the aggregate state of the oil is carried out. Simulation was carried out in Ansys Fluent CAD for two modes, static - with constant heating of the oil at 340K and dynamic, at which the heating temperature varied with time from 340K to 270K. Heat transfer in the event of a change in the aggregate state of a substance is widely used in cases where it is necessary to achieve the maximum efficiency of heat exchange. In this case, the energy is expended on the phase transition of the substance, for example, to evaporation from the liquid phase. The advantage of the heat-sink design described in this work is a rather high rate of heat transfer, greater resistance to various influences, including mechanical ones, which is primarily ensured by the simplicity of construction, eliminating the drawbacks of classical designs, which are cumbersome (the presence of an external cooling circuit ) and the limited rate of heat transfer.

Keywords: heat dissipation, numerical methods, aggregate state, computational experiment, heat exchange efficiency

In the article, the authors carried out a computer experiment in Ansys Fluent CAD to study the efficiency of a heat sink surface in terms of reducing the temperature of a heat-loaded source. Providing optimal thermal conditions for electronic products is one of the most important problems in the design of radio electronic equipment. Increasing the temperature of electronic products significantly reduces the reliability of their work. The work is devoted to numerical modeling of the heat sink surface efficiency of a pin radiator with an internal heat source. A conclusion is drawn about the ineffectiveness of performing a heat sink pin surface, not the entire surface is equally effective.

Keywords: thermal mode of equipment, pin heat sink, numerical methods, aerodynamic flow

In this paper, we consider the application of the optical heterodyning method for signal processing of a receiving device. The simulation of the developed scheme was carried out in the environment of OptiSystem. Also presented are the results of modeling, explaining the principle of operation of this scheme.

Keywords: optical heterodyning, radio frequency, L-band, signal spectrum

The absorbing apparatus serves to extinguish the impact when the wagons cohere and move. Most of the energy, about 80%, in this system is absorbed by a friction unit consisting of a friction wedge and a fixed plate. Absorption of energy in this system occurs due to the work of frictional forces arising during longitudinal motion of the pressure wedge with respect to the friction plate. Due to the large shock-frictional loads, intensive wear and destruction of the cermet cake occurs, which adversely affects the energy capacity of the absorbing apparatus. To eliminate these shortcomings, studies were conducted to create a new material. After numerous experiments, a composition was obtained with the optimum content of components, which maximally satisfies the working conditions of the friction unit and the requirements imposed on these devices.

Keywords: absorbing apparatus, friction unit, cermet, wear resistance, friction plate, powder material, sintering technology

The analysis of the projects for securing the soil foundations, which are part of the new construction projects of educational institutions in the Rostov region in 2016-18, is carried out. On the example of the construction of schools in the cities of Rostov-on-Don, Taganrog, Shakhty, Novocherkassk, Aksai and the village of Chaltyr, the main technical and technological solutions for soil consolidation are considered, depending on the engineering and geological conditions of the construction sites

Keywords: cementation, injector, soil, consolidation, foundation, soil piles, retaining walls, sediment, subsidence, deformation

The article gives an overview of the ways to utilize the heat of the boiler exhaust gases. In conditions of actualization (both technical and economic expediency) of application of technologies for fuel economy and environmental protection, the use of aggregates based on the internal combustion engine and microturbines with the utilization of the heat of the cooling system and exhaust gases has found application. Deep cooling of combustion products of natural gas both in boilers (condensing boilers) and in special condensing heat exchangers (utilizers) makes it possible not only to organize the full utilization of the physical heat of the flue gases (the lowest heat of combustion of the fuel), but also to select the latent heat of condensation Water vapor. The coefficient of efficiency of the boiler-aggregate will be increased in this mode by 8-12%, provided that the boiler operates in the optimal mode. Cooling of combustion products also reduces the content of nitrogen oxides in flue gases, incl. With the use of heat pump plants. The efficiency of the implementation of projects for the installation of condensing heat exchangers depends to a large extent on the number of hours of operation at maximum capacity in the mode of deep utilization. In this connection, we propose a variant of optimization of the boiler room thermal scheme with the heat recovery of the flue gases.

Keywords: Heat recovery boiler, boiler house thermal scheme, optimization, boiler, flue gases, heat generating unit

The problem of identification of defects in the construction in the form of a wall element is considered. Numerical simulation of the structure is carried out in the Ansys finite element complex. The investigated model of a wall structure has a defect in the form of a through crack, of a certain length. The edges of the cracks do not interact with each other. The excitation of the structure under pulsed loading is considered. Wave field displacements at control points are analyzed. Identified signs of identification of crack-like defect.

Keywords: numerical modeling, wall element, defect, crack, identification, finite element modeling, dynamic analysis, oscillations, displacement wave field

The problem of identification of defects in the construction in the form of a wall element is considered. Numerical simulation of the structure is carried out in the Ansys finite element complex. The investigated model of a wall structure has a defect in the form of a through crack, of a certain length. The edges of the cracks do not interact with each other. The excitation of the structure under pulsed loading is considered. Wave field displacements at control points are analyzed. Identified signs of identification of crack-like defect.

Keywords: numerical modeling, wall element, defect, crack, identification, finite element modeling, dynamic analysis, oscillations, displacement wave field

The article is devoted to the study of the problem of determining the mechanical properties of vibrating centrifuged concrete with a combined aggregate and fibrous additive, which was basalt fiber. Experimentally obtained data on the optimal consumption of disperse fiber. The dependence of the strength properties of concrete with a combined aggregate on the amount of fiber additive added is graphically presented. Also graphically shows the increase in the speed of the passage of an ultrasonic wave in the body of concrete when determining the prismatic strength. It was found that the presence of porous particles in a concrete mixture facilitates the directed distribution of mineral fibers along the section of the concrete ring. This, in turn, leads to an increase in the fracture toughness of the material. The conclusion is made that the joint introduction of porous and fibrous additives into the concrete mix determines the production (at the same cement costs) of high-strength concretes with an increased crack resistance, as evidenced by the data on the displacement of the boundaries of microcracks formation in the direction of their increase.

Keywords: structures and products of annular section, centrifuged concrete, vibrocentrifuging, mechanical properties of vibrating centrifuged concrete, combined aggregate, fiber additive, basalt fiber, prismatic strength

An experimental device designed for the detection of peripheral veins during the injection and infusion was developed on the basis of recording the difference in the intensity of the optical signal reflected from the vessels and surrounding tissues. The device allows to perform the detection of the locations of vessels, to determine their projection, to confidently distinguish veins and arteries. The effectiveness of the application is shown in tests on healthy people and patients with diabetic angiopathy. The device is very compact, has a simple design and low cost.

Keywords: infrared light, optical pair, photodiode, LED, introscopy, vascular detection, complicated intravenous access, peripheral vein, photoplethysmography, angiopathy

The article deals with the effectiveness of high-strength concrete for the design of concrete columns on the example of 20-storey residential building in Rostov-on-Don. The results of the ground floor columns calculations for different types of concrete strength are presented. The columns are presented in two variations. The first variation is 600x600 B25 from the second underground floor to the tenth floor and 500x500 B25 from the eleventh to twenty-fifth floor. The second one is 500x500 B60 from the second underground floor to the seventh floor, 400x400 B60 from the eighth to the eleventh and 400x400 B25 from the twelfth to the twentieth floor. The analysis of the study results showed the technical and economic efficiency of the use of high-strength concrete (in particular, concrete class B60) due to increasing the strength characteristics of the compressed elements. This is also due to reducing the cross-sectional size and weight of the columns, saving reinforcement, causing a reduction in the cost of elements as a whole.

Keywords: high-strength concrete, compressed elements, construction of tall buildings, columns, Lira-SAPR, calculation of structures