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 paper presents a comparative assessment of the methods for generating radiation in the form of a two and three-frequency symmetric packet of discrete frequencies, both traditional on the basis of the Mach-Zehnder modulator operating at various operating points, and the author's on the basis of tandem amplitude-phase modulation. The generated emissions are special cases of an ultra-narrowband packet of discrete frequencies used to construct radio-photonic vector analyzers. Based on the results of computer simulation of the shapers in specialized software, a qualitative and quantitative assessment of the purity of the generated radiation is given, which confirms the results obtained for mathematical models and their adequacy to the described physical processes.

Keywords: modulation of optical radiation, ultra-narrowband packet of discrete frequencies, Mach-Zehnder modulator, tandem amplitude-phase modulation, electroabsorption modulator

The paper presents the concept of constructing microwave photonic vector analyzers of a new type based on an ultra-narrowband packet of discrete frequencies, formulated as a result of a comparative analysis of existing methods for constructing optical vector analyzers.

Keywords: optical vector analyzer, microwave photonics, microwave photonic vector analyzer, modulation of optical radiation, ultra-narrowband package of discrete frequencies

This article presents the results of a study of the tendency of composites based on magnesium oxychloride cements to deformation changes. The dependence of the degree of deformation of light magnesian concretes on the conditions of their hardening has been determined. The main factors influencing the deformation of light magnesia concretes have been established. The influence of hardening conditions on the intensity of deformation changes is shown. Revealed the reasons causing uneven deformation of light magnesia concrete. A method for the manufacture of light magnesia concretes has been determined, which prevents their uneven deformation and subsequent violation of the geometry of the structure. It has been established that the introduction of modifier additives, such as cellulose ethers, helps to reduce the delamination of concrete magnesia mixtures, improve their homogeneity and reduce the unevenness of deformation changes over the sample volume.

Keywords: magnesium oxychloride cement, volumetric deformations, shrinkage, expansion, warpage, hardening conditions

Most of the electric motors used in industry are squirrel cage induction motors. In modern industries, various types of starting and controlling asynchronous motors are used, the choice of the starting mode determines the necessary means of automating the electric drive, which directly affects the functionality and, accordingly, the final cost of the project. Direct starting is the most common way to start an electric motor. The main advantage of direct start is the maximum cheapness of the control scheme implementation. The disadvantage of direct starting is high starting currents, exceeding the rated ones by 3-8 times, which leads to increased wear of the windings and causes a reduction in the service life of the electric motor. A high initial starting torque is accompanied by a significant impulse, which places a significant load on both the mechanisms of the electric drive itself and the units of technological equipment. Star-delta starting is used to reduce inrush currents. It allows you to make a soft start with a star circuit, and during operation, a triangle is turned on, providing the maximum power of the unit. In contrast to the starting modes discussed earlier, the soft starter stabilizes the starting characteristics, providing a gradual increase in power and stable operation of the motor, which allows to extend the service life of the electric motor and technological equipment. The use of frequency converters allows you to optimize production, reduce energy consumption, and increase the service life of equipment. The inverter also protects the electric motor in the event of a short circuit, deviations from the nominal mains voltage and controls the operating temperature of the electric motor, preventing it from overheating. Having considered the features, as well as the advantages and disadvantages of starting modes of asynchronous electric motors, it is possible to determine what equipment is needed to implement a specific task of an automated electric drive.

Keywords: automated electric drive, asynchronous electric motor, starting mode, soft starter, frequency converter, automatic control

The design of internal combustion engine (ICE) control system for an unmanned aerial vehicle (UAV), providing reduced fuel consumption and stable operation of ICE at an altitude above 5000 m above sea level, has been created. A system of remote adjustment of the internal combustion engine parameters in real time during the flight of the UAV was developed and manufactured.

Keywords: unmanned, aircraft, control system, internal combustion engine, remote adjustment, radio channel

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

The choice of a method for transporting hydrocarbons from the shelf of the northern seas is an urgent task, necessary for the economic justification of a project for the development of an offshore field. A comparative analysis of existing transportation schemes allows us to take into account both the advantages and disadvantages of possible options, namely, the natural and climatic features of the region, the technical capabilities of contractor organizations, the cost of field development facilities and vehicle rental.

Keywords: hydrocarbons, continental shelf, transport scheme, analysis, tanker, gas and oil pipeline, onshore infrastructure, offshore infrastructure

The article deals with the actual problematic elements of the organizational structure of enterprises in the construction of industrial buildings and structures. Using the method of optimizing the effectiveness of the existing organizational system, the necessity of introducing organizational and technological modules was revealed. An algorithm for optimizing the organizational structure of an enterprise during the construction of industrial buildings is proposed.

Keywords: optimization of organizational structures, organizational and technological modules, modules-stages, optimization algorithm

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

The purpose of this work is to determine the possibility of using a fine fraction (screening) of landfill waste located on the western outskirts of Volgograd as recultivating soil. The following priority indicators were determined in the selected samples: hydrogen index (pH), the content of benz(a)pyrene, petroleum products and groups of elements related to heavy metals: mercury, cadmium, arsenic, lead, zinc, nickel and copper, namely forms extracted with acid and buffer solution and ammonium acetate with a pH of 4.5. Excess of normative values in the samples was noted for such toxicants as cadmium, nickel and copper. The value of the total indicator of chemical pollution Zc without taking into account the toxicity coefficient was 30.03, and taking into account - 46.34, which corresponds to the categories ""moderately dangerous"" and ""dangerous"". It is determined that the small fraction of landfill masses belongs to the 4th class of waste hazard - low-hazard. Direct use of sieving as a soil recultivant is not possible. It is necessary to carry out measures to detoxify it. Due to the presence of components with carcinogenic properties, acceptable detoxification directions are extraction or encapsulation of heavy metals.

Keywords: landfill masses, fine fraction, chemical pollution, hazard class

It is known that diseases of the oral cavity and anomalies of the dentition are polyetiological. Prevention of these diseases is extremely important for the health of the population of Russia, and in order to ensure maximum effectiveness of preventive programs, it is necessary to develop them taking into account all factors and taking into account the characteristics of various regions of the vast extent of the country. At the same time, the level of development of information technologies and, in particular, geographic information systems makes it relatively easy to solve such problems, which until recently required huge labor costs.

Keywords: prophylaxy, epidemiology, statistical analysis, information technology, geoinformatics

The purpose of the article is to study the material on the topic "Basalt fiber", to generalize the studied material and the accumulated experience on the given topic. The article discusses the advantages, disadvantages, problems of use and achievements in the study of basalt fiber used for the production of building materials as a reinforcing component. The analysis of the average cost of basalt fiber in comparison with other types of fiber is carried out, a conclusion is made about the advantage of using basalt fiber. General conclusions have been made about the advisability of using basalt fiber for the production of building materials, and unexplored areas of using this type of fiber have been identified.

Keywords: basalt fiber, reinforcement, stress-strain states, compression, tension, bending, shear, deformation, adhesion

The work is devoted to some questions of prosthetics of human limbs. A prototype of a prosthesis control system based on electromyography is suggested, which is not inferior to existing analogues, but significantly benefits in its cost.

Keywords: bionic prosthesis, electromyography, EMG sensor, amplifier