The work is devoted to the analysis of the frequency characteristics of a piecewise homogeneous coaxial Bragg microwave structure with irregularities in the inner conductor. The article presents varieties of piecewise-homogeneous Bragg coaxial microwave structures, their options for practical application and implementation, as well as the possibility of their modernization, and also considers a recurrent method for calculating a piecewise-homogeneous transmission line. The possibility of using lumped capacitances in an equivalent circuit is considered and simulation is carried out in the electrodynamic simulation program with initial parameters.Based on the results of the work done, it was concluded that the effect of lumped capacitances included in the equivalent circuit of a piecewise homogeneous coaxial Bragg microwave structure significantly improves the frequency characteristics of a single-wave calculation in comparison with full-wave simulation. When approaching conditions favorable for the propagation of the first highest mode, it is necessary to include the effects of its propagation in the calculation.

Keywords: Bragg microwave structure, reactivity, permittivity, coaxial cable, microwave range

The construction of a Polar gas turbine power plant is carried out on permafrost soils. Features of the construction of reinforced concrete structures of foundations and other elements in the permafrost zone implies high requirements for strength, density and frost resistance. A new composition of the concrete mixture with improved physical and mechanical properties is proposed. Superplasticizing additives and production waste are used in the composition of the concrete mixture.

Keywords: foundation, permafrost, borehole piles, superplasticizer, sulfuric acid sludge, concrete mix, strength, frost resistance

The article proposes new compositions of a fast-hardening concrete mixture using Portland cement, fine and coarse aggregates, basalt fiber, a complex modifying additive including acetone-formaldehyde resins and magnesium chloride (bischofite). The results of scientific and experimental studies are presented and the influence of the proposed additives on the formation of the structure, rheological and physico-mechanical properties of fast-hardening concrete is determined. Analysis of the test results showed that the proposed formulations, including a complex additive and basalt fiber, contributed to a decrease in the water-cement ratio, increased mobility of the mixture and increased strength of hardened concrete in the early and final hardening periods.

Keywords: concretes, oil and gas storage, modifying additives, fiber, mobility, setting time, strength

The task of planning the trajectory of a mobile robot is considered in the following formulation: it is necessary to choose the optimal trajectory of the robot's movement over hilly terrain from one point to another among the many available paths. The developed algorithm for planning the optimal trajectory of movement of mobile objects allows minimizing energy costs when moving over hilly terrain. The optimal trajectory is determined from the condition of minimum of the functional of the rolling friction forces work. To find the optimal trajectory on which the friction forces work is minimal, is used the dynamic programming method. The proposed algorithm for planning the optimal trajectory can be used to reduce energy consumption in the process of moving over hilly terrain not only autonomous robotic systems, but also other vehicles.

Keywords: planning algorithms, rolling friction force operation, dynamic programming, optimization according to the selected criterion

The article examines the issue of calculating the depth of compression stresses when using a spherical indenter in order to increase the fatigue strength of steel parts. When the spherical indenter is pressed, elastic deformation of the surface first occurs, and then plastic one. The residual plastic deformation is expressed in the size of the print. The physicomechanical properties of the processed material are not taken into account, the process of pressing a spherical indenter into a steel sample in the ANSYS program is modeled by the final element analysis (FEA).A bilinear deformation diagram was fed, which is set in the program by the modulus of elasticity, yield strength and Poisson's ratio. At the next stage, a finite element grid was generated by using the Hex Dominant Method, which divided the model into elements in the form of hexahedra of various sizes. In the contact area, the size of the finite elements was 0.2 mm. The results of calculations of analytical and numerical methods for spherical indenter diameters of 4, 6, 8, 10 mm and various degrees of plastic deformation to determine the depth of compression stresses are presented, compared with known data, the error is calculated. A dependence is derived for a preliminary assessment of the occurrence of residual stresses depending on the diameter of the well after the indentation of the spherical indenter.

Keywords: spherical indenter, bilinear deformation diagram, plastic deformation, indentation depth, compression stress

The conclusion of the relations for the study of the propagation or diffraction of electromagnetic waves in the semiconductor layers of composite materials, which are also recommended to be used in the creation of onboard antennas and microwave devices with less weight. Both exact and simplified mathematical expressions for the rapid quantitative estimation of the complex wave number are obtained. Using the example of carbon fiber plastics with high conductivity, it is shown that their use makes it possible to create waveguide paths and antenna reflectors up to a millimeter wavelength range.

Keywords: carbon fiber, electrodynamics, composite, propagation, absorption, antenna

This article is devoted to the possibility of using random access memory as a pluggable disk array in order to speed up calculations within a heterogeneous computing system. The problems of using a RAID array of hard drives as the main disk space for storing data generated by applications for a heterogeneous system of tasks are considered. The principles of using random access memory as a disk space are presented, as well as the features of connecting to the thus obtained data storage via a network.

Keywords: parallel computing, file system, random access memory, mounting, heterogeneity, computer complex

The subject of research is the development of a service for generating various forms of a given word based on the analysis of words found in the dictionary. The available approaches to solving such a problem were studied and the most relevant one was chosen. The service searches inside the dictionary file with text content in order to automate the process of selecting the necessary words among the entire set. The search for the stem of the word is performed, taking into account the morphology. Performing a morphological analysis of a word, a common basis for all its grammatical forms is found, cutting off suffixes and endings. As a result, the service algorithm allows you to search for all forms of a word by a given keyword, taking into account word forms. At the same time, it also analyzes which part of speech the word belongs to, this allows you to set different methods for determining word forms. For each type of word: verb, noun, adjective, adverb, its own algorithm is used to highlight word forms. The peculiarity of the service is that it allows you not only to search for word forms in the dictionary, but also allows you to generate sets of word forms based on the type of a given word. The service operates on the Linux platform under the control of the Apache web server. Free software tools were used for development. The development was carried out in JavaScript, HTML and CSS, the server-side programming language PHP7 was also used.

Keywords: search engine, document analysis, linguistics, word forms, morphology, word generation, web service

The calculation for progressive collapse with variation and comparison of different scenarios was carried out for the frame of a unique high-rise building of a multifunctional complex. At the first stage, the calculation was performed in a quasi-static formulation, the maximum deflections for two destruction scenarios were determined. The requirements for the state of limited operability in conditions of progressive collapse are completed. At the second stage, the calculation was made in a dynamic formulation. A modal analysis of the frame was previously performed in order to determine the forms of vibrations that will correspond to the expected deformations of the structure in the event of the occurrence and development of the process of progressive collapse. It is established that the maximum deflection of the plate when calculated in a dynamic formulation is 27.6% greater than in a quasi-static one. The residual deflection after the attenuation of the oscillatory process is 4.6% less than in the static calculation. Therefore, the object of study is safe from the point of view of the possibility of an emergency situation, accompanied by partial destruction of load-bearing structures.

Keywords: parametric architecture, evolution of shaping, aerodynamics, finite element method, analytical surfaces

In the article the authors consider the influence of development institutions on the formation of the knowledge economy, it is proposed to evaluate their quality in the form of an index of institutional development. A method of evaluation based on objective indicators is proposed. A model for ranking regions is presented, including the calculation of indicators, on the basis of which a comprehensive integral assessment of the index of regional institutional development is carried out.

Keywords: knowledge economy, regional economy, innovation economy, innovation activity, socio-economic development, institutional infrastructure

With the right approach, the heat generated by chillers in an indoor ice rink can be used to melt ice, a dehydration system, or to heat a concrete pad under a layer of ice. In this way, energy can be saved. For the purpose of accumulation and subsequent distribution of thermal energy in the building, a reservoir that accumulates heat can be used. Heat is removed from the chiller condenser by a water cooling circuit, which is connected to the coil of an indirect heating boiler (heat accumulator). The coil heats the water that circulates in the heating circuit. Since the load on the ice can change during the day, heat extraction will occur in different amounts. For efficient transfer of thermal energy from one heat exchanger to another, it is necessary to control the speed of rotation of the pump impeller so that the controlled function is maximum. If the speed is insufficient, then the heat exchange flow will receive less heat. On the contrary, if the drive drives antifreeze too quickly, then the coolant will not have time to heat up. A mathematical model of the system was compiled from a plant condenser and a boiler with heated water, a dependence on the speed of the coolant (antifreeze) and the temperature difference at the inlet and outlet of the accumulator was revealed.

Keywords: heat accumulator, temperature control, shell-and-tube heat exchanger, optimal regulator, freon

The article presents an analysis of the problems of diagnosis and restoration of the human respiratory system after diseases, including COVID-19. The review of analogues of small-sized spirometers is carried out. On the basis of which an individual small-sized device has been developed for effective training of the respiratory system. The functional scheme of the pneumatic trainer is described and the main simulator-game scenarios for achieving a therapeutic effect are analyzed.

Keywords: respiratory system, COVID-19, pneumatic trainer, portable device, pressure sensor, MEMS technology

This paper presents the principle of operation of the algorithm for translating a graphical representation of neural network models into a program code within the framework of a neural network repository. Based on the obtained data structure, it is possible to carry out sequential generation of program code in a general-purpose programming language.

Keywords: neural network model, neural network, repository, graph model, programming, translation, spatial data, algorithm, topology, architecture

The article discusses the features of numerical modeling of the limits of fire resistance of structures under the influence of standard and hydrocarbon temperature regimes. After carrying out the assessment using the proportionality coefficient, it is necessary to carry out a verification calculation of the structure tested under the standard temperature regime of the fire, and if the results obtained coincide, the calculation of the structure under the hydrocarbon regime.

Keywords: fire resistance of concrete building structures, standard fire temperature regime, hydrocarbon fire regime, fire resistance

The essence of the proposed is the arrangement of the frame from the channel around the coating beam. At the same time, the frame elements can be subjected to controlled effects, in the form of overvoltage in them, which is realized by specially installed traction brackets. The study of the proposed structural and technological solution, implemented by a channel frame, was carried out using digital technologies based on numerical modeling. In the proposed calculation model, the beam reinforcement area was changed due to the introduction of a reinforcement frame. In the Etabs software package, using the finite element method, transverse forces and moments were calculated in the newly formed system - a beam plus a channel frame. The paper considers the issue of the influence of the frame on the transverse force in the beam. Using the technology of processing large arrays of numbers, a mathematical model of the process was obtained when the beam was reinforced with a channel frame. A consistent analysis of the mathematical model was carried out, which allowed to state the correctness of the decision and assign the design dimensions of the device and its technological parameters.

Keywords: reinforced concrete beam, reinforcement, channel, reinforcement, shear force, load, numerical method, mathematical modeling, numerical modeling, mathematical model, Etabs software package