Objective. The aim of the study is to develop a computational model of a thermoelectric system (TPS) for cooling discrete semiconductor devices (DSD), implemented in the Elcut application software package, and to conduct a corresponding numerical experiment on it.

Method. A new type of DPP cooling system has been developed, which uses several TEM sections that provide heat removal from both the lower and upper surfaces of the fuel elements, which increases the heat exchange surface between the cold source and the REE element and increases the heat removal efficiency. Using the finite element method, a computational model of this system is constructed based on the solution of the problem of thermal conductivity for a multi-element structure of a complex configuration, each component of which is characterized by thermal and electrical parameters.

Result. A numerical experiment was carried out using the calculation model. As a result of it, the results of a numerical experiment were obtained in the form of a three-dimensional picture of the temperature field of the DPP - TPP system when it reaches the stationary mode, as well as graphs of temperature changes over time in the center of discrete semiconductor devices at various values of the cooling capacity of the thermoelectric module (TEM).

Conclusion. As a result of the numerical experiment, it was found that the proposed design of the cooling TPP fully allows solving the problem of ensuring the required temperature regime of the DPP in the range of its power up to 75 W. At the same time, the use of sections of thermoelectric modules from thermoelements identical in their geometric, electrical and thermal characteristics makes it possible to increase the manufacturability of the device, as well as to ensure its operation in optimal current modes. 

Objective. The aim of the work is to develop a calorimetric stand that allows simulating the operation of an energy-efficient two-evaporator refrigeration unit of a household refrigerator or freezer.

Method. In the course of the work, a calorimetric setup is described that allows conducting experimental studies to determine the cooling capacity and energy efficiency of a modernized refrigeration unit of a household refrigerator.

Result. Currently, new resource-saving circuit solutions for household refrigeration equipment have been developed. The developed solutions make it possible to increase the efficiency of the refrigeration unit, as well as to reduce its energy consumption. Theoretical calculations confirming these indicators have been carried out. To confirm the calculated values, automated experimental studies are required to determine the parameters of the refrigeration unit. The paper proposes a description of an automated calorimetric stand that allows simulating the operation of an energy-efficient dual-evaporator refrigeration unit of a household refrigerator or freezer.

Conclusion. The designed calorimetric stand will allow carrying out complex experimental studies to determine the cooling capacity of the modernized refrigeration unit when operating on various refrigerants. The experimental setup also makes it possible to measure the temperature and pressure during the operation of the refrigeration unit, as well as to determine the influence of various factors on its characteristics. 

Objective. Currently, access to the information resource of the ATS AS is implemented through the access control subsystem of the information security facility based on the mandatory and discretionary methods of access control developed in the 70s of the last century and requiring improvement. The purpose of the study is to analyze existing methods and, on this basis, select the optimal method for regular users to access information resources of automated systems of internal affairs bodies.

Method. System analysis, graph theory method, and verbal (verbal) modeling.

Result. A new aspect of the method of access of regular users to information resources of automated ATS systems, based on the use of hierarchical metrics of semantic proximity, is disclosed.

Conclusion. The use of a method based on semantic proximity significantly reduces the processing of a large amount of information, respectively, increasing the performance of automated systems. 

Objective. A high-quality "cloud storage" of data should ensure the confidentiality, integrity and availability of information in the "storage". The use of "cloud storage" for storing information in backups is associated with their possible loss. Ensuring the confidentiality of information in the "cloud storage" implies that by "uploading" data to the "cloud storage", the user must be sure that an attacker will not be able to obtain information from the storage. The aim of the study is to develop an algorithm for using a cross-platform mobile application to protect information in the "cloud storage" of IS.

Method. The study is based on the use of a cross-platform approach to creating applications.

Result. The analysis of existing approaches and frameworks for the development of crossplatform mobile applications was carried out. It is proposed to create an application based on the Xamarin framework. To ensure the confidentiality of information, it is proposed to encrypt them before uploading data and backup copies of files. Encryption involves hiding the original type of the file from unauthorized use using crypto-algorithms, when the owner of the encryption key is the authorized user. To implement the function of encrypting data and backup copies of files uploaded to the "cloud storage", it is proposed to use the Rijndael symmetric block encryption algorithm, adopted as an encryption standard according to the results of the Advanced Encryption Standard (USA) competition.

Conclusion. A cross-platform mobile application can be compiled and run efficiently under iOS and Android operating systems, encrypt files and upload them to the "cloud storage" with the possibility of subsequent decryption. 

Objectives. The aim of the work is to improve the information security of businesstype networks, as the most susceptible to external threats for the purpose of commercial espionage.

Method. The study is based on the use of an original mathematical algorithm that allows clustering networks of arbitrary topology and constructing a partial order matrix. On the one hand, clustering allows you to identify network agents that have the same information access to the network, on the other hand, partial order reflects the position of a single cluster in the hierarchical structure of the entire network.

Result. This approach allows assessing the potential threat to the network depending on the position of the agent in the network that has been attacked. On its basis, a methodology has been developed to determine the degree of openness of an entrepreneurial network to the influence of external factors for each agent of the network. It allows you to identify network agents that require increased security in relation to external influences, since a potential attack on them has the most negative consequences for the entire connection, which emphasizes the practical significance of the result.

Conclusion. The developed technique is practically significant and can be used to assess the information security or integrity of a network of any nature, represented as a directed graph. 

Objective. The aim of the study is to build emulators of the main sensors of a small spacecraft (SC).

Method. The quality of recovery is determined by the standard deviation (RMS) of the data from the standards. The study is based on the application of the dynamic programming method.

Result. A review of works in the field of application of stable characteristics - invariants, in the applied areas of pattern recognition and state control of complex technical systems is carried out. A method aimed at identifying failures and building small spacecraft sensor emulators based on the analysis of stable indicators: correlation and covariance coefficients is proposed and tested. The proposed approach makes it possible to increase the overall reliability of the information-measuring system of a small spacecraft (SC). In the future, to emulate a failed sensor, it is planned to use multiple correlation of time sequences.

Conclusion. In the general case, recognition is reduced to comparing the graph structures of objects to the correct matching of hierarchical image models based on various invariants. Control of the states of complex systems is based on the use of stable characteristics that act as invariant or subinvariant descriptors. Invariants in various applications help to recognize the current situation with a sufficient degree of accuracy, usually reducing the dimension of the problem. 

Objective. The purpose of the study is to determine the velocities of seismic waves on the ground.

Method. To determine the velocities of seismic waves in different parts of the earth's crust, using a sample obtained by mathematical modeling, an artificial neural network was trained. Using at the input of the trained neural network, the real values of the differences in the times of arrival of seismic waves on the ground, we obtain at its output the values of the velocities of seismic waves on the ground.

Result. A method for determining the velocities of seismic waves on the ground using artificial neural networks is proposed. Dependences of the root-mean-square error in determining the velocities of seismic waves on the ground on the training epoch, as well as the distribution of errors in determining the coordinates of the earthquake hypocenter using the obtained information about the structure of the earth, are obtained.

Conclusion. The proposed method makes it possible to determine the structure of the earth's crust more accurately than previously proposed mathematical methods.

Objective. In the development of the electronic industry, one of the strategic directions for the development of organizations is personnel training. The costs of training and the implementation of training courses in the context of the COVID-19 pandemic are significant. The purpose of this work is to increase the efficiency of engineers' activities in computer-aided modular design systems based on printed circuit boards (PCB) through the formation of the necessary competencies and recommendations for the designer.

Method. The article provides an overview of methods and systems for the formation of CAD content in various industries. It is proposed to create a training system updated in real time, which will improve the skills of engineers and overcome gaps in production The structure of an automated learning system (AOS) is developed. What makes this structure different from others is an ontological model domain and an adaptive model. An adaptive method has been developed for constructing a CAD training course for enterprises in the instrument manufacturing industry, which is distinguished by the use of mechanisms for the interaction of learning models. The individual characteristics of the engineer being trained to form an adaptive learning scenario are taken into account in these learning models. This allows providing the optimal learning trajectory to the student with a reduction in learning time.

Result. This research method is used to improve the skills of engineers in the course "Design of modules based on PP" at the X52 shipyard in Vietnam. As the results of the experiments, we can achieve a result that this effective method increases the level of engineering competence by 11.3% and decreases the total training time by 25.4 % compared to +the traditional method. Moreover, this method also reduces the cost of additional training for new engineers.

Conclusion. The obtained results demonstrate the need to develop an adaptive training system. Thank to this method, the competency of the software-based modular design engineers will be developed. The adequacy of this method has been previously confirmed by the experimental data and the previous studies. 

Objective. In modern technology, elastic structures of structures, machines, and technical devices are widespread. In real conditions, the rods experience oscillations from dynamic and kinematic disturbances. The aim of the work is to develop methods and algorithms for solving problems of oscillations under dynamic and kinematic disturbances.

Method. The study is based on the application of the hypothesis of flat sections and the d'Alembert principle.

Result. The problem of longitudinal free and forced vibrations of rods is considered. As a result, the displacement function of transverse sections in the longitudinal direction of the rod was found, the spectra of natural forms jn and natural frequencies w_n of vibrations were obtained.

Conclusion. A set of calculation programs has been created, which makes it possible to solve problems of rod vibrations. Spectra of eigenfrequencies w_n and eigenmodes j_n(x) of vibrations are obtained, and u(x, t) is found, the function of displacement of cross sections in the longitudinal direction of the rod. 

Objective. The study of the adhesion of reinforcement with tuff concrete on quartz sands, prepared both on ordinary Portland cement and expanding additives.

Method. The solution is carried out by conducting an experiment, for this purpose, the manufacture and testing of tuff-concrete prisms with one centrally located reinforcing rod of a periodic profile of class A-400 was carried out, within the time limits established by the norms.

Result. According to the results of the experiment, it was found that the adhesion of reinforcement to concrete is mainly determined by the compressive strength of concrete. The strength of the reinforcement's adhesion to concrete increases with the increase in the strength of concrete. In the studied compositions, the effect of the concentration of a large (tuff) filler or an expanding additive was not detected.

Conclusion. The adhesion of reinforcement to concrete is largely determined by the strength of the concrete itself. The type of binder (the presence of an expanding additive) and the concentration of coarse aggregate do not significantly affect the adhesion of reinforcement to concrete. The dependence between the coupling of reinforcement during punching and the strength of concrete is revealed. An assessment (indirect) of the endurance and crack resistance of the coupling can be given by (the value of the conditional coupling) l_sl, determined by the length of the visually visible cut of the consoles on concrete samples during penetration tests. In tuff-concrete of the studied compositions, the l_cl decreases with an increase in the strength of concrete. In tuff concrete with RD, the endurance and crack resistance of the coupling turned out to be higher compared to tuff concrete on ordinary Portland cement. 

Objective. The aim of the study is to develop an algorithm for the method of calculating the area of light openings of buildings, which allows the transition to a differentiated accounting of light climate resources at any geographical point.

Method. The study is based on methods for designing natural lighting in buildings.

Result. The mathematical model of the light regime of premises has been improved, taking into account the peculiarities of the redistribution of light fluxes in the designs of skylights, rectangular lamps and in inclined lighting devices.

Conclusion. On the basis of calculations using a mathematical model, the coefficients of the light climate for the city of Nalchik were obtained, the use of which will allow, with the improvement of the microclimate in the premises, to increase the technical and economic efficiency of natural lighting systems. 

Objective. The purpose of these studies is to develop a methodology for assessing the seismic hazard of territories and a methodology for making an optimal design decision based on various criteria, including criteria for quantitative parameters of soil vibrations, taking into account regional peculiarities.

Method. Estimation of quantitative parameters of seismic events registered on the territory of the Republic of Dagestan and adjacent areas by analytical and numerical methods. Determination of the reliability of buildings based on probabilistic models.

Result. A method for estimating the parameters of soil vibrations based on the processing of instrumental records of known earthquakes, taking into account the characteristics of soils, is proposed. A method for making an optimal design decision is proposed, taking into account the parameters of soil vibrations and other target functions.

Conclusion. The analysis of the obtained results showed that with an increase in the thickness of the loose layer, the magnitude of the maximum acceleration increases, the range of unstable fluctuations of the periods at the same time lies in the range of 0.1-0.5 seconds. The construction of buildings should be based on the parameters of the vibrations of the soils of the construction site, taking into account the lithological composition of the soil and other physical and mechanical properties. 

Objective. The paper considers controlled effects on changes in the properties of components and the control effect of technological methods and techniques for obtaining composite building materials with a set of specified properties.

Method. Methods of mechano-physical, physicochemical, nanotechnological influence were applied.

Result. The system-structural approaches are systematized and generalized by control actions at the stage of structure formation, technological stages, formation of the optimal structure and properties of cement concrete. The physicochemical principles and mechanisms of structure formation are given, based on establishing the role of controlling the mechano-physical, physico-chemical, nanotechnological methods of influencing the cement-water system. The possibility of controlling structural transformations in binder systems, including through the use of technological influences, has been revealed.

Conclusion. The implementation of the impacts on the components of cement concretes will ensure the targeted design of the structures of modern building materials. 

Objective. The purpose of this study is to create a static calculation algorithm to determine the maximum bearing capacity of a lenticular membrane-pneumatic system for covering large spans under the action of external force loads.

Method. A numerical study of a large-span membranepneumatic structure was carried out by the step method of incrementing parameters using the finite element method and the Euler-Cauchy numerical procedure of the third order of accuracy at the step.

Result. The authors have developed a technique for computer static calculation of geometrically and physically nonlinear lenticular membrane-pneumatic systems of coatings for large span structures by the iterative method of parameter increments with the phased application of the finite element method in the form of the displacement method, the universal equation of gas state and the improved Euler-Cauchy numerical procedure of the third order of accuracy.

Conclusion. Ignoring the aftereffect in the calculations means the imbalance of the system due to unbalanced pneumatic forces calculated with an error of 11.2% and affecting, as the calculations showed, in the amount of approximately 7% percent on the increment of excess air pressure in the lens. 

Objective. The purpose of the study is to establish the patterns of accumulation of irreversible soil deformations from repeated loading.

Method. When loading soils, the balance between external and internal forces is established gradually over a more or less long time. Therefore, with a single application of a cyclic load, such an equilibrium can be achieved only in a relatively long time.

Result. An approximate method is proposed for calculating the magnitude of the deformation developed as a result of the action of a cyclic load. The cases are determined when it is necessary to take into account the viscous component of deformation and when the latter can be neglected. It has been established that when determining the deformation of soils that has developed during a single application of such cyclic loads that are characteristic of the process of their compaction by machines, in all cases, except for rolling them with rollers on pneumatic tires, the viscous component of deformation can be ignored.

Conclusion. In a relatively short time of the load, the state of equilibrium can be achieved only in the process of soil deformation by repeated loading. With an increase in the number of loading repetitions, the soil gradually hardens, and the deformation decreases. This occurs both due to the irreversible and reversible parts of the deformation. Consequently, the soil deformation modulus increases from cycle to cycle. 

Objective. Determination of the degree of development of various types of microorganisms and their effect on the physical and mechanical properties of concrete.

Method. Assessment of the possibility of concrete to serve as a substrate for various types of biodestructors was carried out using the determination of moisture absorption and pH of water drawing of concrete samples.

Result. Experimental mechanism of action of various microorganisms on concrete is established. Taxonomic composition of microorganisms most aggressive to concrete is determined. The impact of biofouling on the physical and mechanical properties of concrete was assessed.

Conclusion. The results of the investigation serve as the basis for competent selection of the most effective methods of corrosion protection of concrete structures operating in biologically aggressive environments. 

Objective. An analysis of already known technological methods for molding shotcrete and a construction 3D printer confirmed the effectiveness of building additive technologies. The proposed extended additive technology, the method of electrostatic molding of products and structures made of reinforced concrete, will find its practical application in construction.

Method. The principle of obtaining electrostatic concrete is the electrostatic deposition of a semi-dry mixture of binder, finely ground sand and fibers on a shaping base made of steel or carbon mesh. The resulting layers are dosed with finely sprayed water with various additives, the mixture sedimentation and moisturizing cycles are repeated until the desired thickness of reinforced concrete is obtained.

Result. Electrostatic buildup of concrete layers occurs without mechanical impact on the shaping base. This means that the basis of the product can be made from a small amount of material in a short time and in any available way. The first layers of fiber-reinforced concrete, after holding time, give strength to the shaping base. As the thickness of concrete increases, the strength of the product increases, outstripping the increase in mass.

Conclusion. The electrostatic molding method makes it possible to manufacture thin-walled body parts of complex shape, spatial shells, architectural and construction parts, and structures of membranes, hollow columns and racks, power line supports, reclamation gutters, large-diameter drainage pipes, tanks, etc. 

Objective. Development of compositions of fire-retardant vermiculite-concrete composites for reinforced cement structures. Investigation of the properties of fire-retardant vermiculite-concrete composite and fine-grained concrete for two-layer reinforced cement structures.

Method. Methods for increasing the fire resistance of reinforced concrete structures are considered. Research is focused on the development of fire-retardant composites using expanded vermiculite and volcanic ash. To improve the physical and mechanical properties of the fire-retardant composite, a mixture of Portland cement, gypsum, lime, basalt fiber, saponified wood resin, volcanic ash and expanded vermiculite has been developed. For the study of vermiculite concretes reinforced with basalt fiber, a second-order rotatable plan of the regular hexagon type was used.

Result. Fiber-vermiculite concretes are proposed, which have improved fire-retardant properties compared to known compositions. This is due to the better preservation of the fiber-vermiculite-concrete layer when heated as a result of fiber reinforcement. Also, thanks to the addition of SDO, the fire-retardant properties of the composite increase due to the additional porosity of the fiber-vermiculite-concrete. The parameters of the "stress-strain" diagram of a vermiculite-concrete composite and fine-grained concrete have been obtained.

Conclusion. Vermiculite concretes with an average density of 480-560 kg/m3 have the best fire-retardant properties. The developed two-layer reinforced cement structures have high fire resistance. 

Objective. The purpose of the study is to determine the effect of a span on the operation of large-span structures; the features of the work of large-span coatings, which are widely used in the design and construction of modern buildings and structures, are considered and analyzed.

Method. Designs and design techniques are given that allow designing buildings and structures with a large span. Examples of the calculation of a large-span frame are considered, the corresponding drawings are made, nodes and other details are given that can serve as a visual aid in the design of the relevant buildings and structures. Large-span beam trusses and frame systems are considered.

Result. The main methods for reducing long-span bending moments, as well as design techniques that reduce span displacements, are proposed and tested.

Conclusion. The developed design schemes of frames and trusses provide minimal metal costs, and also allow determining the influence of the parameters and geometry of frames and trusses on metal consumption.