In this article, the object of study is a research drying chamber of a convective type, in the design of which a condensing heat exchanger based on a vapor-compression heat pump is introduced. The drying process of lumber refers to energy-intensive technologies, since the share of drying in the cost of finished materials reaches 50% [1]. In the presented experimental study, comparative results of two operating modes of the experimental installation are presented: standard (soft mode) and recirculation mode with a condensate dryer. The obtained experimental drying curves show that the cost of electrical energy, taking into account the option with a condensing heat exchanger, decreased by 7.75% compared to the standard.

Keywords: drying modes, drying, heat pump unit, heat recovery unit, material balance, heat balance, moisture content, heat consumption, experimental setup

The article considers variants of arrangement of various reactive power compensation devices, the choice of location of which took into account both modes of operation of power grids and voltage levels in the nodes. Mathematical modeling made it possible to form an optimal calculation algorithm based on a multi-criteria approach, taking into account the possible voltage increase at the corresponding substations. However, this approach is accompanied by some increase in active power losses, so the final conclusions should be based on expert procedures.

Keywords: reactive power compensation, mathematical modeling, installation site, power losses, multi-criteria approach, calculation algorithm, power system, substation, compensating devices

The article is devoted to the use of artificial intelligence tools to solve technical problems in the construction industry. It is noted that the use of neural networks will allow taking into account the behavior of materials in various experimental conditions. The authors present a comparative analysis of approaches to neural network training, in particular, the structures of multilayer and LSTM networks are considered. It is established that LSTM networks are more effective in solving problems of identification properties of materials.

Keywords: neural network, non-destructive testing, identification task, multilayer network, LSTM network, impact indentation, indentation, strength properties of materials, neural network technologies, statistical distribution

This article analyzes the calculated fire curve in accordance with the ignition heat source in the compartment. To predict the calculated fire curve, the exponential equation proposed in the previous study was compared with the heat release rate measured in a fire experiment. The lag index, which is the main factor used to predict the time it will take to reach the maximum heat release rate, has decreased in proportion to the ignition heat source.

Keywords: fire calculation curve, pipe insulation, ignition heat source, deceleration index, heat release rate

In this article, we investigate the effectiveness of using multiple pipes for heat dissipation. The study assumes laminar flow under steady-state conditions. Various mixtures are numerically investigated at different flow rates. Various nanofluids flowing through multiple parallel pipes have been numerically investigated to study the effects of temperature rise. Thanks to the benefits they bring to the cooling process, nanofluids have opened up a new way to improve the performance of thermal systems. A typical nanofluid consists of a base fluid, which is usually water, and nanoparticles.

Keywords: heat exchanger, flow tube, nanofluid, bottom heating, coefficient of friction, pressure drop

The article describes the well-known design of a tape-shell foundation. Based on the analysis of the known design, a number of factors affecting the limitation of the scope of the tape-shell foundation are derived. In order to ensure the controlled inclusion of the reinforced concrete shell of the foundation in the work, the author of the article proposed the use of a damping gasket under the tape support contours. A gasket made of an easily compressible slab material - polystyrene foam - is compressed under the influence of the load from the walls and columns of the basement of the building, the reinforcement of the shell is stretched and involves the soil of the subshell part of the foundation. At the same time, the strength characteristics of the band-shell foundation increase, the sediment decreases. The author of the article conducted numerical studies to determine the required thickness of the gasket. It is proved that the use of a damping gasket is relevant for soils with a deformation modulus of less than 15 MPa, above this value, the use of a gasket is impractical.

Keywords: tape-shell foundation, reinforced concrete shell, tape support contour, ground whole, auxiliary method of inclusion in the shell, damping gasket, thickness of the gasket

The development of a methodology for the formation of an estimate of a construction object on the basis of its information model is considered, taking into account the state of development of software systems for BIM modeling and the peculiarities of regulatory regulation of the construction of construction projects in Russia. The factors that limit the possibility of drawing up estimate documentation for the information model have been identified. Taking into account the identified limitations, a set of operations necessary for the formation of an estimate for a construction object based on its information model is presented.

Keywords: BIM, 5D BIM-model, estimate documentation, civil and industrial construction

The construction industry is considered to be one of the most unsafe industries, and as a result, safety in the construction industry is considered a very important factor. To reduce the number of accidents and monitor workers at a construction site, the article suggests integrating new tracking and communication technologies. The authors analyze the existing similar technological solutions, identify their advantages and disadvantages. A method for organizing monitoring of workers at a construction site using mobile devices is proposed, as well as the architecture of a software and hardware complex. The developed method is a smart system for a mobile device. This solution allows you to monitor the location of workers using a GPS tracker and a built-in accelerometer, and, if necessary, notify them of a possible danger.

Keywords: construction site, accidents, safety in construction, employee monitoring, mobile application, geolocation

The occurrence of convection in a two-layer system consisting of a region of a free fluid and a porous array saturated with the same fluid is investigated. The equations in the Oberbeck-Bussinesq approximation are used to describe the motion of a pure fluid, and the equations based on Darcy's law are used for the porous layer. Using the shifted grid scheme, the plane problem is approximated in natural variables. At the interface, special formulas derived by the integro-interpolation method and taking into account the different types of equations in the two domains are applied. The results of calculating critical numbers corresponding to the occurrence of convection for different heights of the porous layer and Darcy numbers are presented.

Keywords: dconvection, porous medium, Oberbeck-Boussinesq equations, Darcy model, shifted grids, stability

Reducing the consumption of heat resources in construction and housing and communal services is one of the key tasks solved by design engineers. The increase in the thermal protection of buildings is determined by regulatory documents, but construction customers often require it to be strengthened without any feasibility study. The objective of the study is to develop a graphical-analytical model, the analysis of which allows you to choose the most optimal combination of heat resistances of the coating (walls) and translucent structures of a particular building object.

Keywords: energy-saving project, thermal protection of buildings, "indifference" curves, the method of the fastest descent

To provide protection class Br1, С and S2 (not less than 550 m/s) GOST 34286-2017 "Armor clothing. Classification and general technical requirements "use soft armored packages, consisting of several layers of aramid fabric of various surface densities and types of weaving. The most promising are armored packages consisting of fabric weaving, with a surface density of 0.130 kg/m2 and higher.

Keywords: soft armor pack, protection class Br1, protection class C, protection class S2 (not less than 550 m/s) armor protection, ballistic protection, aramid fabric, individual armor protection equipment

The article offers a solution which will enable to reduce dust pollution during earthworks in urban conditions. A special multi-functional mechanism is proposed enabling to perform several important preliminary processes simultaneously - improving an environmental situation on the site of earthworks. The ground surface damping during trench opening and soil unloading from a bucket into a disposal area will make it possible to reduce the fine dust pollution of the air surrounding a work location. The objective of the study is to develop a mechanism reducing the fine dust dispersal when performing trench and pit excavation. The novelty is that a mechanism of special construction has been proposed that can be mounted onto any machine in the construction line.

Keywords: earthworks, dispersal, technology process, trenching, single-bucket excavator, soil disposal area, trench, fine dust, air pollution, РМ 2,5, PМ 10

This article is devoted to the consideration of the possibility of using LED technologies in solving the problems of organizing artificial lighting of the historical part of the urban environment. A unique set of properties of modern LED sources, such as a wide dynamic color spectrum, low power consumption, ease of installation, long-term uninterrupted operation, environmental friendliness of production and operation, chemical and physical resistance to external influences, provides them with a steady demand for solving the problems of street and architectural lighting of historical quarters of the city, emphasizing their originality and uniqueness.

Keywords: artificial lighting, architectural lighting, lighting design, lighting systems, LED, LED technology, energy saving, environmental friendliness

The article is devoted to the analysis of the vertical structure of the acoustic pressure field and the first-mode particle velocity in a hydroacoustic waveguide in shallow water. A waveguide consisting of a water layer with a constant sound velocity profile, a transition layer, and a half-space is considered. The acoustic properties of the transition layer are assumed to be frequency dependent. Formulas are derived that describe the vertical profile of the normal mode of a particle velocity. The transformation of the vertical profile of the first mode with increasing frequency is analyzed. The phase difference relations between the normal mode of acoustic pressure and particle velocity are analyzed. A relationship is established between the change in the vertical structure of the normal modes of pressure and particle velocity and the acoustic properties of the transition layer.

Keywords: normal modes, particle velocity, seabed, attenuation coefficient

Numerical investigations of the dependences of the output characteristics of the ion strontium vapor laser on the pressure and temperature of the active medium were carried out. Based on the results of calculations, a range of conditions for the excitation of the active medium was found for the realization of the multiwave lasing regime on visible and infrared transitions of the strontium ion (λ=430.5; 416.2; 1091 and 1033 nm SrII). A number of patterns were revealed that are inherent in the active medium of a strontium vapor laser, and the physical mechanisms that determine them were established. The investigations results provide a possibility to choose the conditions for optimal excitation of multiwave strontium vapor lasers, as well as to control the relative contribution of various spectral components to the output radiation.

Keywords: multiwave radiation, recombination pumping, self-termination transition, strontium vapor laser, numerical modeling