Integrated Computer Technologies in Mechanical Engineering

The work is devoted to the application of the data-driven approach to determining the yield criterion of unidirectionally reinforced composite materials. This condition has the form of a function of the average coordinate stresses. In contrast to the traditional phenomenological approach, where the form of this function is postulated with the inclusion of a limited number of material parameters, the new approach involves the construction of a grid form of the yield criterion. A numerical determination of the yield strengths of the composite based on the known properties of the matrix and fibers leads to a typical problem of analysis of big data. Based on the finite element analysis of the representative cell, a technique has been developed for determining the yield strengths of the composite under various load paths. Illustrative results are given for special cases of combinations of coordinate stresses.

Fiber-optic pressure instrument transducers with elastic sensors were developed. Functional circuits and the way of proposed fiber-optic pressure instrument transducers work, protected with utility model patents of Ukraine, are described. Developed fiber-optic pressure instrument transducers can be applied in automatic control and regulating systems for different objects.

The article discusses the electrical equivalent circuit for installing a plasma generator in order to highlight the functional dependencies of the steady state of the control system. Experimentally established effect coating mechanism using tungsten carbides and rare earth impurities to the process of increasing resistance parts, which depends specifically introduced into the plasma generation system of controlled variables of internal resistances. This allows the use of a functionally stable control system for a non-stationary plasma medium. Experimental studies have confirmed that plasma formation occurs with the necessary parameters due to voltage stabilization at the target cathode and anode. Also, in order to stabilize the process, it is necessary to correct the current of the ionized flow, and equalize the energy potential of charged particles of the ion-plasma medium. To maintain the specified parameters within specified limits, it is necessary to introduce the corresponding resistance variables into the plasma generation system. Resistance variables are combined into a block of ballast resistors, which ensures the stability of the plasma formation and affects the value of current or voltage. These derived variable coefficients help maintain the functional stability of the specified parameters within the specified limits. This suggests that it is possible to control the flow of ionized particles by controlling their internal resistance. Due to this, the deposition of the tungsten carbide mixture on the workpiece is controlled. Coating using tungsten carbides and rare earth impurities is one of the most common in the production of tools that require high hardness, corrosion resistance and wear resistance.

The geometrically nonlinear deformation theory is used for the far post-buckling analysis of a uniformly compressed rectangular plate. The plate geometrically nonlinear deformation theory is developed using the right stretch tensor and the Biot stress tensor. The plate is assumed thin such that the Kirchhoff hypothesis are applied. The plate material is assumed linear elastic. The simply supported boundary conditions are assumed for the plate deflection function. The in-plane displacements of a plate are not constrained except for the prescribed uniform shortening along the opposite edges. The weak solution is constructed using the Ritz method. The basis functions in the displacement function approximations are assumed as Legendre polynomials and their linear combinations. The nonlinear simultaneous equations are solved by the Newton method. Three equilibrium paths are determined, which originate from the first three bifurcation points; two additional equilibrium paths are found to appear during the post-buckling deformation, which correspond to the formation of the buckle-waves (wrinkles) along the non-loaded edges. Stable and unstable branches of the equilibrium paths are determined, as well the bifurcation and limit points. The variation of the potential energy is demonstrated and the possible points of jump-like transitions between the adjacent buckled configurations are identified, including those with where wrinkles are formed. The high accuracy and convergence rate of the numerical solution are demonstrated.

Today there is a great need in the optimal designing and manufacturing of dimensionally stable precision structures for satellite communication systems and sensing systems, in order to implement the international space programs successfully. It is well known that sandwich panels with load-bearing skins made of polymeric composites based on carbon, organic or glass fibers and honeycomb filler of aluminum foil or other materials providing combined action of skins, feature high dimensional stability. Optimization of design parameters was performed on a specimen of operating section of the composite solar panel with honeycomb filler. Results of the analysis of various reinforcement patterns for the load-bearing skins and rational distribution of material for several loading cases of the solar panel are presented. Technological warpage of these panels was analyzed and assessed. Causes of defects generated during the manufacturing process in the form of continuous and discrete strips of thin load-bearing skins of CFRP (carbon fiber reinforced plastic) were also investigated. With the use of the analytical methods supported by finite element method, the integrated study of the adhesive joint’s bearing capacity of solar panel composite skins with the honeycomb filler at transverse avulsion for the main technological methods of applying the adhesive (as a continuous layer and targeted dosing to the ends of the honeycomb) was carried out. The results obtained allow predicting the fracture behavior of the load-bearing skins’ bonding with the honeycomb filler depending on parameters and properties of the honeycomb cell material and the adhesive layer.

A method for preliminary design estimation of civil light turboprop airplane take-off weight, taking into account the requirements of aviation rules Part 23 “Airworthiness standards for civil light airplane” AP-23 (CS-23, FAR-23), has been developed. The analysis of statistical parameters and characteristics of civil light turboprop airplane has been held. New parameters changing ranges are established. Statistical parameters and characteristics of existing civil light airplanes are specified. A method for light civil turboprop airplane take-off weight preliminary design estimation in three approximations according to the Technical Requirements Specification and recommendations for its implementation is presented. Minimum take-off weight is the accepted as effectiveness criterion. An algorithm for light civil airplane take-off weight calculation in first approximation has been developed. To implement the take-off weight calculation method, software has been developed. It allows studying the influence of the wing geometric parameters (such as aspect ratio ($$ \lambda $$), taper ratio ($$ \eta $$), airfoil relative thickness ($$ \bar{c} $$) and sweep angle ($$ \chi $$)) on aerodynamic performance, power-to-weight ratio and airplane mass characteristics and parameters. The software was tested in the calculation of modern light airplane, namely: A-Viator, Rysachok, King Air C90 GTx, Cessna 441, as well as An-14 and was used in the development of the preliminary design of the KhAI-90 civil light turboprop airplane.

The bearing capacity of construction is usually determined by the strength of the joints, where the stress state is irregular. Most existing mathematical joint models are one-dimensional, and imply a uniform stress distribution in width. However, there are constructions for which classical models are not applicable. To calculate the stress state of such joints, it is necessary to take into account the nonuniformity of stresses not only in the length, but also in the width of the joint. To solve such problems, a simplified two dimensional model of the lap adhesive joint of rectangular plates has been proposed. The simplification is that we consider the movement of the layers only along the applied load. Stresses are assumed to be distributed uniformely over the thickness of the layers, and the adhesive layer works only on shear. These simplifications made it possible to obtain an analytical solution to the problem. The stressed state problem for the adhesive joint of two rectangular plates, one of which is rigidly fixed along one of the sides, and the second plate is loaded with an nonuniform normal load at one of the butts, is solved. The problem is reduced to a system of second-order partial differential equations relatively to the longitudinal displacements of the joined layers. The solution is built using the variables separation method, and is a functional series consisting of eigenfunctions. The boundary conditions on the side are satisfied exactly. Satisfying the boundary conditions at the butts leads to a system of linear equations for the unknown coefficients of the functional series. The convergence of the obtained solution is proved. The model problem is solved and the numerical results are compared with the results of calculations performed using the finite element method. It is shown that the proposed approach is accurate enough for design problems.

Rapid development of unmanned aerial vehicles (UAV) is currently being observed. Expansion of both their applications and the tasks they solve lead to the growth of requirements to on-board control systems. This paper presents various options for constructing an automatic control system (ACS) for the longitudinal motion of the Vertigo small unmanned aerial vehicle (SUAV). A linear mathematical model of the SUAV movement was developed and its time characteristics were obtained. The ACS was synthesized on the basis of a traditional PID regulator, a nonlinear fuzzy PD type regulator and a neural regulator. As a training device of the neural regulator there was a reference model of the aircraft with a training block, which was switched off automatically when the required parameters of quality of transient processes were reached by the control object. The purpose of the work is to synthesize various algorithms of UAV ACS operation, as well as to analyze their influence on the dynamic properties of the SUAV “Vertigo”.

Based on the theory of dimensions and similarity, a method is proposed for obtaining the criteria for the energy perfection of ground launch devices for launching unmanned aerial vehicles. The principle of rationing the appearance of ground launch devices using special similarity criteria is proposed. A criterion space has been built for assessing the energy perfection of pneumatic and pyrotechnic ground catapults depending on the mass of the launched aircraft. The principle of deterministic design decision-making in the formation of the appearance of ground catapults according to the tactical and technical characteristics of the launched unmanned vehicle is proposed.

This work reports Parameter estimation of Propulsion System driven by Brushless Direct Current (BLDC) motor used in multirotor unmanned vehicles, parameters was obtained by experimental process. In order to obtaining the parameters in mathematical model given response to different excitation inputs, the analysis method for system identification that is used is the reaction curve. To establish the structure and parameters that mathematically describe the motor, the motor is stimulated with a step signal, the response to this signal is observed. Response in speed was observed graphically and from the experimental analysis the parameters that define his transitory response were determined then is used numerical approximations using optimization tools as objective function linear regression using least square method through objective function in Python programing language. Finally, the model found was replicated by computer simulation and compared, the relevant parameters were adjusted and validated by comparison between the experimental results and what was theoretically stated.

The article describes the features of the triad method application at the initial stages of aircraft design for the selection of fundamental decisions in aircraft design. The possibility of using the triad method to determine the initial appearance at the stage of conceptual design is analyzed. A brief overview and features of the conceptual design are given in this article. We are considering the general application algorithm and the basic concepts of the triad method. There are examples of the triad method used for the airfoil, aerodynamic design, and the selection of landing gear type. The formulated main postulates which allowed you to transfer this experience to the design of engineering products.

The subject of study in the article is the process of implementing the search for an object, its recognition (its geometric shape) and moving the manipulator to the corresponding coordinates to capture the object using a probe (ticks) and moving it to the given coordinates. The goal is to improve the quality of the robot manipulator when recognizing complex images of objects. Problems: study of human-robot interaction (HRI), gesture recognition for HRI, development of a generalized information processing algorithm, automation of collaboration between the working hand and the person, which should be guided by the movement of the hand using the camera. The models used: gesture recognition model for human-robot interaction. The following results are obtained: gesture recognition algorithm obtained during human-robot interaction, the functional structure of the system is obtained. The scientific novelty of the obtained results is as follows: improved model for recognizing objects of complex shape using the Kinect camera, proposed a special algorithm for gesture recognition in HRI, formed a series of gesture recognition tasks in HRI.

The features of changes in the real and imaginary parts of the complex permittivity of the samples with CdZnTe crystallites in the frequency range 10–103 Hz of the electric field in the absence of exposure to electromagnetic radiation are obtained. It has been shown that composites without these crystals have a higher diffuse reflection coefficient. Under the influence of non-monochromatic light, an increase in the changes in the complex permittivity of the samples with increasing frequency of the measuring field was detected. Moreover, the changes are larger for the samples with the largest crystallite size. The low inertia of changes in the dielectric parameters of the samples under the influence of non-monochromatic illumination is established. Samples with ZnSe (Al) crystallites are characterized by significant changes in the complex permittivity under the influence of non-monochromatic illumination in the frequency range 103–104 Hz. Negative changes of this parameter are especially unusual. The peculiarities of the spectral dependences of the constituents $$ \Delta\upvarepsilon_{\text{ef}}^{'} $$ and $$ \Delta\upvarepsilon_{\text{ef}}^{''} $$ complex permittivity of the structures, measured at a light intensity of 10 mW/cm2, have been established. The changes in the magnitudes of the increments of the real and imaginary components of the complex permittivity under the action of X-Ray radiation with a dose rate of 200 mR/h at different frequencies of the electric field are investigated and their characteristic features are determined. An analysis of the results from the point of view of non-equilibrium electronic processes in semiconductors is presented.

A problem of cutting irregular objects from the domain (rectangular sheet) taking into account technological requirements is studied. As mathematical models of real objects two-dimensional phi-objects, bounded by circular arcs and line segments, are considered. Our objects allow free translations and rotations within a domain. We reduce a collection of technological requirements to geometrical constraints (such as minimal allowable distances, prohibited areas, range of the possible object rotations, changing shapes of objects by adding auxiliary circular zones). A nonlinear programming model of the irregular cutting problem, employing the phi-function technique, is provided. We develop an efficient optimization algorithm, which involves a fast feasible starting point and local optimization procedures. To show the benefits of our methodology we present some computational results.

The article presents an implementation of object recognition methods using the OpenCV library. The analysis of existing approaches, as well as recognition algorithms. The best methods were selected for the quality and number of recognizable objects in the image, taking into account the time to search. A recognition algorithm based on the analysis of brightness histogram (three color components of objects is proposed); a recognition algorithm based on the analysis of the contour length has been developed; programs for counting objects of the same type in the image are developed, taking into account their separate location on the image and the possibility of overlapping (merging contours). The above algorithms are implemented in the programming language C++ using the OpenCV library. The results obtained in the course of using the implemented methods, both individually and in combination, are presented.

The problem of accurate medical diagnosis is always urgent for any person. Existing methods for solving the problem of classification of the state of a complex system are considered. The paper proposes a method of classification of patients’ status in medical monitoring systems using artificial neural networks. The artificial neural networks training method uses bee colonies to simulate less training error. The research purpose is to determine the patient’s belonging to a particular class according to the variables of his condition, which are recorded. Examples of using the method to determine the status of patients with urological diseases and liver disease are given. The classification accuracy was more than 80%.

Recommendation systems have changed the way inanimate websites interact with their users. Instead of providing static information when users search and possibly buy products, recommendation systems increase the degree of interactivity to expand the possibilities provided to the user. Recommendation systems generate recommendations independently for each specific user based on his past purchases and searches, as well as on the basis of the behavior of other users. This article describes recommender systems and their algorithms. Recommendation system is developed using SVD algorithm. The architectural pattern MVC was used. The implementation represents a three-tier architecture (DAL, BLL, WEB). Program realization of recommendation system was made using .Net language.

The advanced methodology of solution synthesis for multi-objective stochastic optimization problems is offered and realized. To validate the methodology regarding to some particular object one solved the problem of robust optimal designing of centrifugal impeller fitted with backward curved blades in the conditions of stochastic nature of the input data.

The article describes the method of image recognition on the example of recognition of Japanese characters. Recognition is carried out by determining the lengths of the contours. After that, the moments of each circuit are compared. Also, taking into account the peculiarities of Japanese characters, the comparison occurs line by line. This approach can also be used to teach writing hieroglyphs. The same principle has been applied to the recognition of road signs.

The method of objects probabilistic search is developed based on the necessary proximity conditions in a Euclidean space, which were previously proved for the Levenshtein’s metric. The method is based on a random selection of k pivots in Euclidean space among the original objects, projecting all source objects in a k-dimensional Euclidean space, filling special hash data structures, and fast search facilities, similar to the desired, based on proven necessary conditions for the objects proximity in Euclidean space. Experimental studies of the proposed method show the higher speed in comparison with the known method.

The article demonstrates the results of the research, which studied the effectiveness of organizing a proper connection between companies and universities. A methodology of employers’ requirements collection and evaluation is given. To get information about the requirements, it is proposed to analyze the open vacancies of companies. The technology for reviewing, extracting and systematizing requirements from the description of employers’ vacancies was created in order to use the gathered information in university Learning Management Systems. It is suggested comparator identification method as a basis for mechanism of vacancies description search, data retrieval, an indicator value transformation, and comprehensive assessment performing. It is proposed the model of requirements collection based on the method of comparator identification. The ontology of employers’ requirements can be used for requirements collection, analysis and estimation. However, there is still a problem of requirements thesaurus creation, vacancies, and features for different specialties in different languages. Description of vacancies in IT sphere is unified enough worldwide. But we cannot say the same about all other areas of industry. That’s why thesaurus of equivalent terms and their translations have to be created. Future work will be directed on the implementation of the suggested approach in the domain of IT specialists.

The article deals with the issues of legal responsibility in the field of cybersecurity. The Law of Ukraine “On the Main Principles of Cybersecurity Provision in Ukraine” of October 5, 2017, was analyzed and it was stated that art.12 presupposes responsibility for any breaches of legislation in the field of national security, electronic communications and information security in case the cyberspace is the place and/or the means of committing any legal offence, is the blanket article and refers to the articles of the Code of Ukraine on Administrative Offence, the Criminal Code of Ukraine, the Civil Code of Ukraine. The authors of the article offer characteristics of the kinds of legal responsibility: administrative, criminal and civil, for violations in the field of electronic communication and information security in the cyberspace, emphasizing that the issues of the robots’ legal responsibility are not regulated by the general Ukrainian law.

Currently, Cloud, IoT, Dew, Edge and touch networks of “things” are allocated as part of the program system. Data at the touch network level is associated with physical objects. At the Edge level, data is separated from objects to form a Digital Twin representation of their state, properties, and behavior with minimal latency. Copies of Digital Twin “things” are stored and used at different levels, but must reflect their current state. Interaction with “things” in IoT, data transport between sensor networks through their boundary nodes is considered. For Edge computing research it is proposed to create physical and virtual models of fragments of touch networks, their boundary nodes, processing of data and organization of access of devices as part of “things” to remote IoT resources. The paper shows how to build a virtual device model in a Proteus environment and assess adequacy versus a physical model. Implemented a piece of wired sensor network with TCP/IP protocol based on open platforms.

With long-term operation of pumping and other equipment, there is often a need to extend the life and assess the residual life. Modern life-time assessment methods are based on three-dimensional modelling and the finite element method. Within the framework of these methods, geometric models are constructed that take into account the thinning of the walls of the pumps as a result of operation. By constructing geometric models, finite element models are constructed. These models are made taking into account the conditions of loading of the structure, tightening of bolted connections, technological and temperature loads. The constructed models allow to assess the strength of the pump casing and the main bolted connections during normal operation and gyro testing. The paper assesses the cyclic strength of these structural elements. The results of the work confirmed a sufficient residual life-time for safety pump operation in the next 15 years.

Collisions between birds and aircrafts during the taking-off, cruising and landing phases have become an increasingly serious and catastrophic issues for aircrafts safety. Aviation standards in force require that the aircraft construction would allow the crew to conclude the flight safely after collision with 1.81 kg bird. A method for analysis of the stress-strained state of laminated airplane glazing at different operational factors is presented. The method includes a technique for strength analysis of the laminated airplane glazing at the bird impact, and a technique for analysis of superfluous pressure. The model of laminated glazing is based on the refined theory of the first-order accounting transverse shear strains, thickness reduction and normal element rotation inertia each layer. The mathematical model of pressure impulse authentically reproducing bird impact is based on the experimental researches. Theoretical results are in good agreement with experimental data that allows recommending the method for working out new airplane glazing elements.

The questions of planning and calculation of prototype magnetic rotor suspension of small engines at making of elaborate machine-building designs in particular pumps, turbo-expanders or expanders of compressor units of small and medium sizes. The preliminary estimation of dynamic descriptions of the rotor systems requires development of adequate mathematical models with taking into account numerous parameters, including design features, such as supports, stiffness and damping characteristics. A laboratory installation of a complete magnetic suspension of a horizontal rotor according to a combined magnetic-electromagnetic type is proposed and implemented. It uses two passive magnetic bearings created using two annular permanent magnets with axial magnetization as two radial bearings. The axial support is an active magnetic bearing (AMB) with stators in the form of armored cores. The functionality of this AMB uses a discrete method and an analog control system. Finite-element modeling was carried out and the dynamic characteristics of the structure under study were calculated. An experimental installation of the rotor propotype was developed and manufactured, with the help of which experimental testing of the developed model was carried out and the reliability of the calculated results was verified. Comparison of calculated and experimental results shows the effectiveness of the application of information technology in the design of complex engineering structures.

This paper deals with simulating the thermal and stress states of the piston and cylinder of a two-stroke diesel engine type D100 for a locomotive using two different methods. The methods are based on the use of various models of piston-cylinder arrangement: one of them uses assembly of the piston-cylinder arrangement and includes all components, but the other uses two models separately: the cylinder and the piston and rings assembly. It was shown that for both methods, the piston temperature fields differ slightly both in zone of the combustion chamber and on the inner surface, and the maximum difference was 8 K in the zone of the first piston ring, but the difference in the cylinder temperature fields is significant, especially in the middle section where the difference reaches 35 K. Transient thermal-stress states of the piston were determined for three programs of engine starting from the cold state (with various initial temperatures equal to 20 ℃; 0 ℃; −20 ℃) and heating it up to its maximum operating mode, and for one program with cooling from maximum mode to idling, every time with stepped loading. Warming up of oil and antifreeze were taken into account. It is shown that temperatures and stresses reach their peaks and then drop in some zones of the piston. The stress reaches a maximum level of 380 MPa at the center of the piston surface from the combustion chamber side when heated with an initial temperature −20 ℃, which is two times more than the stress at steady-state maximum operating mode (192 MPa). The profile of the piston side surface was synthesized taking into account the heating rate. The piston design with different materials of the piston head – VCh60-2, 25H2G2FL, 12DH1MFL – was proposed for D49 and D80 engines. The mean temperature of the piston hottest zone drops by about 40 K in proposed design. The stress also decreased.

The purpose of this paper is to analyze the error in the gas temperature measured by thermocouples. Correlations were established analytically between the dynamic measurement error and the parameters of a thermocouple temperature measuring system. The accuracy of the thermocouple time constant estimation was identified as a crucial factor of the dynamic error. Further, an analysis of the error in an experimentally obtained estimate of the thermocouple time constant was carried out. It revealed that the thermocouple time constant, which well represents its dynamic characteristics, can be accurately estimated with rationally planned experiments. This study provides an in situ analysis that considers the thermocouple as a part of the engine instead of a stand-alone element. The analytical solution demonstrates the correlation behind the errors and dynamic parameters, and pictures a guideline for optimizing the gas temperature measuring system of gas turbine engines.

The efficiency of integrated cooling air at the intake of Turbocharger and Scavenge air at the inlet of working cylinders of the main diesel engine of dry-cargo ship by transforming the waste heat into a cold by an Refrigerant Ejector Chiller as the most simple in design and reliable in operation and by complex in design but more efficient Absorption Lithium-Bromide Chiller was analyzed. A ship power plant of cogeneration type using the relatively low-grade heat of water of a heat supply system with a temperature of about 90 °C, that significantly complicates the problem of its conversion into cold were considered. A new approach is proposed to improve the efficiency of integrated cooling Intake Air of turbocharger and Scavenge Air at the inlet of the working cylinders of the ship main engine of a transport ship, which consists in comparing the required cooling capacity and the corresponding heat needs during the trade route with the available heat of exhaust gases and scavenge air of the cogeneration power plant, determining the deficit and excess cooling capacity of heat utilizing cooling machines of various types, that allows to identify and realize the reserves of improving the efficiency of cooling intake air of the turbocharger and the scavenge air of the main diesel engine through the joint use of chillers of various types. The minimum value of wall temperature and minimum value of exhaust gas temperature at the exit from exhaust gas boiler is determined, at which the permissible speed of low-temperature corrosion at a level of 0.25 mm/year is ensured.

The efficiency of reciprocating gas engines of integrated energy systems (IES) for combined electricity, heat and refrigeration generation is strictly influenced by their cyclic air temperatures. To evaluate the effect of gas engine cyclic air deep cooling, compared with conventional its cooling, the data on dependence of fuel consumption and power output of gas engine JMS 420 GS-N.L on its inlet air temperature at varying ambient air temperatures at the entrance of the radiator for scavenge air cooling were received. The results of treatment of gas engine efficiency monitoring proved non-effective operation of conventional chilling all the ambient air, coming into the engine room, because of increased air temperature at the inlet of turbocharger (TC), caused by heat influx from surroundings in the engine room. A new method of gas engine inlet air two-stage cooling at increased ambient air temperatures and advanced cyclic air cooling system with absorption lithium-bromide chiller and refrigerant ejector chiller was proposed. With this chilled water from absorption lithium-bromide chiller is used as a coolant in the first high-temperature stage of engine inlet air cooler and boiling refrigerant of ejector chiller in the second low-temperature stage.

Reciprocating gas engines are widely used in integrated energy systems (IES) for combined cooling, heat and electricity supply. The fuel efficiency of gas engine considerably depends on the air temperature at the inlet of turbocharger. To estimate the influence of inlet air on gas engine fuel efficiency the data on dependence of fuel consumption and power output of gas engine on its inlet air temperature were received for Jenbacher gas engine JMS 420 GS-N.LC of cogenerative type with using the heat of exhaust gas, scavenge air, engine jacket cooling water and lubricating oil for heating water to the temperature of about 90 ℃. The hot water is used in absorption lithium-bromide chiller to produce a chilled water, which is spent for technological needs and feeding to the central air conditioner, that provides cooling ambient air incoming the engine room, from where it is sucked by the engine turbocharger. The data on dependence of fuel consumption and power output of gas engine on its inlet air temperature received by processing the monitoring data are very usefull for improving the efficiency of conventional cooling system with chilling the engine room incoming air followed by heat influx from surroundings, that leades to increased air temperature at the suction of turbocharger and enlarged cooling capacity spent for cooling.

This work deals with development of a monitoring system for the stress-strain state of bolted connections of hydraulic turbines. The wireless strain gauge module is an autonomous hardware element, with its own embedded power supply. The transfer of information from the module to the data recording and processing equipment is performed by acoustic interlinking through the impeller body and the shaft of the hydrogenerator. Processing the results of measurements of the stress state of bolted joints is carried out using methods for assessing the residual life. The approaches proposed in this work allow constructing a system for monitoring the residual life of bolted connections of hydraulic turbines.

One the main problem during development of self-organized networks such as wireless sensor (WSN) and mobile ad-hoc networks (MANET) is creation of effective control system, which can cover a lot of management tasks such as topology management, routing management, radio resource management, security management, quality of service management etc. For this purpose it proposed hierarchical model of intelligent control system for WSN and MANET described in Sect. 1. The novelty of the model lies in using the graph theory to make a formal description of the functional subsystems of the network (vertices of the graph) and their interaction processes (edges of the graph). Using of proposed model can accelerate and systemize the network design process considering their functioning environment and hierarchical structure of their control system. Using of intellectual agents technology and multiagent systems allows to minimize the service traffic and use network and node resources more efficiently. One particular management task intended to plan the optimal topology of network nodes is described in Sect. 2. There was formulated a mathematical statement of the problem of finding a rational WSN topology using unmanned aerial vehicles (UAVs), which consists of problem of sensor localization in monitoring zone and problem of UAV relays localization in the space for the organization of connected network with desired characteristics. Rational WSN topology, built according to these principles, will reduce traffic and reduce energy consumption at the nodes, which in turn will increase network lifetime and reduce the total cost of its maintenance.

The paper follows the implementation of “Good practices of public environmental expenditure management in transition economies” suggested by UN Economic Commission for Europe in Ukrainian context. The study illustrates that Ukraine follows the UNECE’s good practices in some points, however its actual performance when it comes to environmental effectiveness, management efficiency and fiscal prudence is half way less than the best possible performance. The full success of copying UNECE’s good practices has not been observed in the Ukrainian case. However, the plausible scope conditions for successful copying for developing roadmap for remedying the situation on environmental protection project management in Ukraine can be suggested.This paper seeks to contribute to the call for more research on the internal and external drivers and barriers to modernization of public financial management in the Central and Eastern European countries. Previous research, discussing the context of Central Europe shows that the issue of the relation between economic growth and environmental protection at the state and municipal levels has become increasingly important in recent years, e.g. in case of Czech Republic. However, since its independence, Ukraine has been a major receiver of external aid not only financial one, but also in the form of knowledge, advices, recommendations, good practices, etc. This articles builds up on Røvik’s translation perspective on knowledge transfer to illustrate how “Good practices of public environmental expenditure management in transition economies” suggested by UN Economic Commission for Europe have been reproduced by Ukrainian government and how this policy translation can be explained in Ukrainian context.

The article presents models of achieving communicative competence in English as a foreign language. It also deals with the views on the essence of the notion communicative competence and its structure. In the context of studying English as a foreign language it has been proposed to consider communicative competence in two main aspects: as the result of studying English and as the ability to successfully implement communicative behavior in a certain situation. Communicative competence as the result of studying is achieved by practice and achievement motivation. Communicative competence as the ability to successfully implement communicative behavior can be explained by the Yerkes–Dodson law.

The proposed methodology can be used to more accurately analyze and predict project results. The methodology is based on the interaction of the method of evaluating the project’s timing and budget - PERT and the method of constructing a multivariate forecast of the dynamics of the external environment - the decision tree. The combination of these methods excludes their shortcomings separately. Thus, the proposed methodology visualizes the development of the project in a graphic way and includes a probabilistic assessment of the project scenarios. The relevance of the work is due to the fact that many projects are currently being implemented in various spheres of human life, but not all projects achieve their goals, including IT projects. According to The Standish Group, around the world last year $ 750 billion was spent on software development and implementation projects, and only 36% of projects were completed successfully, while 48% were only partially successful, i.e. went beyond budget or on time, and the remaining 16% failed. As a result, $ 120 billion was spent on failed projects of $ 750 billion.

At the current level of development of various forms of foreign economic activity, an organization of any level of management may be faced with the need for cooperation with foreign entities. In most cases, such cooperation occurs in the form of project activities, has its own characteristics and significant differences, which, in turn, depend on the scope of activities and goals. Therefore, for the successful implementation of a specific project, it is necessary to identify the distinctive features of this type and form of international project, which will allow choosing the right project management approach. In order to identify classifiers that will optimize the methods and tools of specific project management and improve the efficiency of their implementation, the theoretical issues of approaches to the definition of “international project” have been studied in the article. The project classifications had been also analysed, and the main classification features and categories that are most commonly used in the scientific literature and practical activities had been considered. In the course of the study it was found that the presented approaches to the classification of projects do not take into account the specifics of the implementation of international projects. As a result, the authors proposed classification features specific to international projects.

The subject of the study in the article is the processes of assessing the airspace in controlling small unmanned aerial vehicles (sUAV) traffic management. The goal is to improve the quality of air traffic control, taking into account the avoidance of conflicts involving three or more sUAV. Problems: to develop a mathematical model of the probabilistic traffic map, as well as to formalize the construction of a random geometric graph model for the estimation of alleged sUAVs conflicts and collisions; To implement algorithms given models construction for airspace automation. The models used: Poisson process whose intensity model is used for building a probabilistic traffic map, random geometric graph model is used for calculate the number of possible conflicts involving the sUAV. The following results are obtained. A formalized model of the sUAV location map has been created taking into account: the given region with the specified population density and the expected number of operations during the specified time interval. This model was used in the construction of a random geometric graph, in which, taking into account the minimum distance possible for the approximation of two sUAVs, an estimation of the probability of conflicts and collisions was conducted. The model is the basis for obtaining an algorithm for estimating the factors limiting the capacity of the airspace, as a result of the occurrence of difficult solvable conflicts. The scientific novelty of the obtained results is as follows: The random geometric graph model is improved by formalizing the position of the vertices. The vertices, taking into account the law of the Poisson process, are placed in the cells of a given region. This allows us to obtain an objective picture of the location of the sUAV in the city’s airspace. Two-dimensional models of probabilistic traffic maps (Dutch model Metropolis, model Cal) have been further developed, due to the formalization of the initial sUAV placement, taking into account the law of the Poisson process. This will help to determine the technical requirements for ensuring uninterrupted operation of small unmanned aerial vehicles in the urban airspace.

The operation of air coolers of railway air conditioning (AC) systems is characterized by considerable variations in current heat loads according to actual climatic conditions on the route lines. This causes increased changes of refrigerant flows. Over filling the air cooler coils by liquid refrigerant recirculation enables excluding a decrease in heat flux within variations in current heat loads and provides increasing the heat efficiency of air coolers compared with conventional air coolers with complete refrigerant evaporation and superheated vapor at the exit. Thus a larger deviation of current heat load on railway route lines are permited without falling air cooler heat efficiency. The method to determine the rational design heat load on air coolers of railway AC systems, providing closed to maximum refrigeration output generation over considered time period, was developed.

To increase the reliability of speech input systems, the emotional state of the operator shall be taken into account. The article presents a method and device to compensate for deviations of the displacement of the components of the speech spectrum. The essence of such compensation is that in the process of voice input of information, the operator has the ability to visually control their own condition. Therewith, it becomes possible to correct the spectrum by the operators in real time by self-monitoring their condition, and subsequent hardware elimination of the spectrum deviation from the “reference standard”. This “reference standard” represents a pre-spoken series (alphabet) of words used by operator. Visualization can be organized in the form of LED matrix, where each of the three gradations of the functional state – “large deviation”, “average deviation”, and “reference standard” – will correspond to a certain color of the matrix.

A problem of lossy image compression with providing a desired quality according to a given quality metric is considered. Several approaches to its solving are discussed. A two-step approach based on using the averaged rate-distortion curve is proposed and tested for a coder AGU based on discrete cosine transform. It is shown that it is often possible to use two iteration steps instead of sufficierntly larger number of iterations that makes compression with providing a desired quality faster. Meanwhile, there are ranges of visual quality where further modifications are needed to produce a desired accuracy of quality providing.

Digital image compression technology based on the application of atomic functions is presented. The fundamentals of this algorithm and the results of its comparison to the algorithm JPEG are given. It is shown that Discrete Atomic Compression saves more memory than JPEG with the same quality of results. It follows that application of Discrete Atomic Compression makes it possible in the future to reduce the cost of storing, processing and transferring a huge number of digital images via communication networks.

The subject of the research is the processes of constructing the optimal structure of game modules and the methodology for synchronizing them on the Internet. The aim of the work is to create prototypes of game modules with synchronous multiplayer. The physics of a bullet and a car was developed from scratch. The basic methods and tools of building gaming systems are considered. It is proposed to use property replication and remote procedural calls to create multiplayer. The configuration of Internet packages and calculations on CPU/GPU are optimized.

In the process of research, the authors described a computational method for synthesizing solutions to problems of multi-criteria optimization (based on the use of parallel computing) and decision-making with a priori data uncertainty, based on a memetic algorithm that implements the joint use of an evolutionary method with parameters changing from generation to generation: coding, fitness and relaxation functions, Decremental Neighborhood Method, and the random path generation method.

The article presents an implementation of methods for obtaining the form and appearance of real objects. The analysis of existing approaches, as well as recognition algorithms. The best methods were selected for determining an object in three-dimensional space. Reviewed by method of object recognition to determine the distance from the camera to the marker and methods for determining the position of the object in space. Algorithm for positioning an object in space is developed with the using of the OpenCV library functions. As a result, calculations of relative coordinates of the found object are carried out. Information selection rules based on information are suggested.

Modern virtualization techniques and server architecting solutions are studied. In order to reduce development time and assets cost, there is a great need in full utilization of all calculation resources for both dedicated and virtual servers. Containerization allows shorten environment integration and software deployment time basing on virtualization and tighter integration on high abstract level. The detailed description and analysis of common containerization techniques is given. Comparative analysis of modern solutions shows that the containerization orchestration systems are the best solution which advantages allow optimizing resource utilization and addressing arisen challenges. The features of the joint use of container orchestration and management system together with different cloud providers are given. Comparison of modern CI/CD approaches is given. Environment quality and its configuration for active application deployments make major impact on needed calculation resources quantity. Common environment architecture approaches in context of containerization usage are described. CI/CD solutions allow significantly reduce deployment time and increase reliability.