Proceedings of VNTU

Assessment of the impact of factors which influence the energy efficiency of res during the balancing of electrical energy system modes

2022-12-18T13:01:53+00:00

The paper evaluates the factors caused by the massive construction of renewable energy sources (RES), which in turn reduce their energy efficiency, and the significant generation capacity, which depends on weather conditions, causes difficulty in balancing the modes of electric power systems. General-purpose electrical networks are used to transmit the electricity generated by them. They affect the technical and economic parameters of electrical networks. In particular, with an increase in the amount of electricity in the balance of electric power systems (EPS).

A method of structuring electricity losses caused by power flows in electrical networks, which appear in them from green generation, is proposed, which will make it possible to increase the efficiency of RES use in mode balancing by including them in the generation schedule for the next day. As a consequence of improving the accuracy of generation forecasting, which increases the energy efficiency of such sources.

The method is based on a mathematical model of the electrical network for determining losses, in which current distribution coefficients in circuits from RES nodes and node voltages are used. As a result, a matrix of power loss distribution coefficients in lines is formed, which depends on the flow of power along the line from each circuit node. To form the array of data needed to determine losses, the steady-state mode of the electrical network is calculated or experimental measurement data is used. It is shown that the values of electricity losses in electrical networks caused by RES can be used during the operational planning of the electricity balance in the UES and, since they are addressable, their cost can be compensated accordingly.

Operational management of the balance of power and electric energy in the electrical power system with renewable energy sources

2022-12-18T13:55:58+00:00

This work demonstrates the effects of the active use of renewable energy sources (RES) in the unified energy system (UES) of Ukraine, in particular, maintaining the balance in the network for its reliable and high-quality operation. In the energy strategy for the development of renewable energy sources in Ukraine until 2035, a rapid increase of the installed RES capacity is planned, i.e. the task of maintaining balance sheet reliability in the conditions of an increase in the share of RES in the UES of Ukraine is quite urgent. Forecasting of the electricity balance is based on the generation forecast, electricity consumption in a given period of time, as well as fuel reserves and the volume of generating capacity reserves. Renewable energy sources have a non-uniform nature of generation, and therefore endanger aspects of balance reliability. This problem is key for Ukraine in light of the integration of Ukraine's energy system into the European ENTSO-E network. As a result of the conducted research, it can be stated that the improvement of the situation is possible only with an integrated approach and the implementation of appropriate technologies, namely: technical, economic and institutional technologies. The introduction of technologies will make it possible to improve monitoring and management of energy systems; economic implementations will contribute to the reform of retail pricing and taxation of electricity supplies, taking into account the payment they supply for electricity and covering part of the cost of the general infrastructure; institutional innovations will change the functions and responsibilities of management subjects. Improving coordination between transmission and distribution network operators will become a priority.

Analysis of the working efficiency of the unified power quality regulator to change voltage fluctuations

2022-12-28T09:55:38+00:00

Improving the quality of electricity is an urgent task for the development of the electric power industry, aimed at reducing electricity losses, increasing the service life of electrical equipment, and ensuring conditions for the normal technological process of electricity consumers. This article shows the analysis of the effectiveness of the application of a unified power quality regulator (UPQR) to minimize the range of voltage fluctuations (VQ), flicker dose and general harmonic distortion in the distribution system, which, as a result, improves the quality of electricity. The final simulation of the study is carried out using MATLAB/Simulink. To demonstrate the performance of URYAE, an analysis of the effectiveness of compensation of voltage fluctuations and the flicker indicator was carried out. URYAE was studied on the example of generation of active and reactive power of URYAE into the network and efficiency of compensation of passive current components. The initial data for performing calculations of voltage fluctuations are information on the parameters of the electrical network and a schedule of a random, rapidly changing electrical load, which causes changes in the network voltage, the swings of which can reach large values, for example, due to the inclusion of an asynchronous motor with a large starting current. Such phenomena are also caused by technological installations with a rapidly changing mode of operation, which is accompanied by active and reactive power surges and discharges by consumers such as welding machines, etc. The main objective of the study is to improve the quality of electricity, increase the service life of electrical equipment and ensure the conditions for the normal technological process of electricity consumers. The indicators characterizing the KN were considered: the range of voltage change (Ut) and the flicker dose (Pt). The purpose of the work is to analyze the efficiency of the URYAE with rapidly changing and non-linear load.

Decentralized coordination control of distributed cyber-physical systems with continuous objects

2022-12-28T12:28:36+00:00

A distributed system is one that consists of separate elements located at different points in space, the functions and resources of the system are divided between the elements, and the location in space affects the functioning of the system as a whole. A special case of distributed systems is distributed control systems (DCS). In today's market, there are a large number of distributed control systems created at different times and by different companies. In the work, a method of decentralized coordination of control of distributed cyber-physical systems with continuous objects is developed, a RKFS model with a continuous production object and resource state management is developed, which is characterized by taking into account the mutual influence of controlled elements of a continuous production object and resource costs for production and is presented in in the form of a two-flow graph, an indicator of the level of coordination is proposed, which determines the state of coordination in the interval from chaos to a given deterministic state, which allows to evaluate the effectiveness of the coordination system, the criterion of coordination of the RKFS with continuous production facilities, which is based on the model of a continuous production facility, and distribution of states of object elements in space and time, the method of forecasting the state of distributed cyber-physical systems with continuous objects, which is based on the RKFS model with a continuous production object and resource management of state and space-time spectrum, has been improved states and disturbances.

Algorithm for determining the places of installation of reclosers in branched distribution electric networks

2022-12-30T11:12:01+00:00

Air line 10 kV overhead lines are made, as a rule, according to a radial scheme with aluminum non-insulated wires on reinforced concrete supports with an average length of 15 km and in some cases can reach 40 km (data according to Khmelnytskyi REM). In these networks, devices of automatic sectioning and redundancy are practically not used, which leads to the disconnection of all consumers that are powered by these PLs in the event of emergency situations. For example, Air line 10 kV F-5 of the Khmelnytsky REM with a length of 23 km, the estimated value of SAIDI is 714 minutes, and according to the resolution of the ccording to the Resolution of the National Commission for Regulation of Public Utilities №1175, the value of the SAIDI indicator for rural networks should not exceed 300 minutes.

Reclosers are used to increase the reliability of the power supply. The use of reclosers makes it possible to reduce the number of de-energized consumers in the event of short circuits by sectioning the overhead power line and the possibility of reserving it from another substation for the period of repair work on damaged sections of the substation. Some distribution system operators follow the path of replacing line disconnectors that switch on-site teams, but this approach does not always correspond to the optimal placement of reclosers to ensure the maximum effect of improving reliability indicators, in particular, when using short-circuit indicators.

A method of determining the optimal location of reclosers in distribution electrical networks, taking into account the installation of short-circuit indicators, is proposed, which will provide the greatest effect of improving the reliability of power supply. This method is based on the use of a matrix of paths, which makes it possible to automate the calculation of the SAIDI indicator depending on the location of the recloser and the number of short-circuit indicators.

Electrical Transmission Line Damage Identification System for Distribution Electrical Networks

2022-12-30T11:58:59+00:00

In the paper shows, that one of the important directions of the development of the electric power industry both in the world and in Ukraine is the improvement and construction of electric power networks and systems according to the Smart Grid concept. The main idea of such systems is a reliable, energy-efficient and high-quality energy supply, which based on the growing role of management as a leading factor in the innovative development of electric power and the construction of high-performance information and computing infrastructure. One of the main components of Smart Grid is the diagnosis of emergency modes and damage monitoring. This is because damage to electrical networks affects the quality and reliability of electricity supply to consumers. Therefore, the task of quickly and accurately determining the place of damage is important. The effective solution of this problem gives a significant economic effect due to the reduction of power supply interruptions, the reduction of transport costs for bypassing electrical networks, and the minimization of the total time for the organization of repair and restoration works. It shown that one of the ways to increase efficiency is the use of means of identifying emergency conditions in sections of both cable and overhead electrical networks. A diagram of the location of damage indicators on the section of the electrical distribution network presented, which allows determining the direction of the search for the location of the damage. A comparative analysis of current measuring transformers of optical and electromagnetic type carried out. It shown that a significant number of advantages of optical measuring current transformers, which can be used in damage indicators, can be provided by measuring current transformers of the electromagnetic type. It is shown that in order to ensure the creation of a damage indicator based on the Smart Grid concept, which allows to reduce the time of searching for the cause and location of an emergency situation to a minimum, as well as to ensure connection to operating overhead and cable lines without removing voltage by connecting the output of the secondary winding of the measuring current transformer of the detachable design to the measuring converters directly placed near the current measuring transformers with the help of a mechanical spring fastener. A block diagram of a specialized information and measurement system with a damage indicator was created, taking into account the requirements of the Smart Grid concept, which allows to reduce the time of searching for the cause to a minimum.

Hybrid Sensor for Determining Air Gap Anomalies in Synchronous Generators

2022-12-30T12:15:51+00:00

In the paper shows, that from the moment of the start of production until the moment of final decommissioning, a number of physico-chemical and thermomechanical processes take place in the structural elements of powerful hydrogen generators (HG) in its rotating and non-rotating structural elements. Over time, these processes lead to a change in the actual technical condition of the HG nodes and the development of defects that affect the efficiency of the HG. The determination of the actual technical condition of HG based on the evaluation of a complex of control and diagnostic parameters of various nature, which include electrical, mechanical, temperature, magnetic, and technological parameters. The reliability of determining the actual technical condition, determining the presence of defects in the facility, assessing the possibility of further use of the energy facility depends on how fully the controlled parameters reflect its actual technical condition. The air gap between the rotor and the stator is one of the main nodes of the HG, in which the mechanical energy of the water pressure transformed into electrical energy. The design feature of the air gap in the HG is its relatively small size compared to the bore diameter of the stator. The size and value of the asymmetry and uneven distribution of the air gap largely determine the actual characteristics of the HG and its behavior during operation, and significantly affect a number of other characteristics of the machine (Value of the end magnetic fluxes and losses that occur in the extreme packages of the core and pressure plates of the stator; on the value and distribution of losses on the surface of the rotor poles; as well as on the area of permissible modes of operation of the generators). Determining the value of asymmetry and uneven distribution of the air gap only based on the data of the air gap control does not allow to fully determining the type of defect that led to the change in the air gap distribution on a working machine. For increase the efficiency of determining the types of defects associated with air gap anomalies, it is advisable to use hybrid sensors, which, in addition to capacitive air gap sensors, contain an additional sensor in their structure was shown.The calculation of the additional information component in the form of EMF is given.

Information technology of provision recommendations in emergency situations

2022-12-18T12:23:13+00:00

In the work, information technology for providing recommendations in emergency situations was developed, which helps the dispatcher of the State Emergency Service of Ukraine when talking to a person at the scene of an emergency, and also correctly determines recommendations for further actions in an emergency, while the brigade on duty heading to the scene of an emergency. An analysis of models and methods of providing recommendations in emergency situations was carried out. The types and classes of information technologies that solve the task of providing recommendations are defined. The combined application of fuzzy logic and expert systems in the process of providing recommendations in emergency situations is proposed. The design of software tools for providing recommendations based on the methodology of analysis and design of Structured analysis and design technique (SADT) systems has been completed. Software tools have been developed to determine the necessary key parameters by which each characteristic of an emergency situation is determined. In accordance with the tasks, the structural organization of the software product is proposed, the class diagram and the scheme of the algorithm of the program are developed and described. Software for providing recommendations in emergency situations has been developed, which improves the quality of providing recommendations in emergency situations due to the integration of technologies of expert systems and fuzzy logic. Software testing and analysis of information technology for providing recommendations in emergency situations was carried out. The work was carried out in accordance with the direction of scientific research of the Department of Computer Sciences of Vinnytsia National Technical University and the plan of scientific and educational and methodological work of the department.

Information technology predicting the sale prices of houses in king-county by machine learning methods

2022-12-18T13:22:16+00:00

The sale and purchase of the real estate, in particular housing, and houses are extremely important for our life. Most people turn to real estate agencies to realtors in order to purchase quality housing and at the same time at the best price for the buyer. You should rely not only on personal assessment or assessment of third-party experts but also use price prediction systems that, using the features of the house (area, number of floors, location, number of bedrooms, year of construction, etc.), are able to predict its possible price. The report is devoted to the task of improving the accuracy of predicting the sale price of houses in King-County using machine learning methods by creating an information technology for predicting this price. The analysis of sales and purchases of real estate has been carried out, and signs that have an impact on the pricing of houses have been previously proposed. The dataset was selected, and its main features were described, preliminary data cleaning was carried out, exploratory data analysis was carried out, a rule for filtering anomalous values for the selected dataset was proposed, many possible models were selected, they were trained, and the optimal one was selected, the result of the models was presented and analyzed, for comparison the prediction accuracy of similar solutions is given. An optimal LGBM regression model was obtained, and its application made it possible to obtain a prediction accuracy of 0.876, which is more than 0.82, as in the best analog. The scientific novelty lies in the fact that the information technology for predicting the sale price of houses in King-County has been further developed using machine learning methods, which makes it possible to increase the accuracy of such a prediction compared to analogs.

Development of a Fuzzy Matlab inference algorithm for decision-making under uncertainty conditions for designed objects

2022-12-28T12:21:52+00:00

The decision -making method in the face of uncertainty for designed objects is proposed. Uncertainty arises in open decision -making tasks in which the dice does not know the total set of factors. The uncertainty situation is characterized by the fact that the choice of a specific action plan can lead to any result from a certain set of options, but the likelihood of influencing random factors is unknown. The purpose of the article is to create a fuzzy algorithm for making decisions in the face of uncertainty for designed objects in the Matlab environment. The study is based on the use of decision -making method by means of a linguistic variable, which helps to increase the effective decision in a new difficult situation for designed objects. Two types of Mamdani and Sugeno algorithms in the Fuzzy Logic Matlab package were used to realize this goal. Previous studies were used to build a fuzzy knowledge base, namely indexes and quantitative indicators of the impact of the projected object on the components of the environment (air, surface water, soils). Expert rules "If - then" for both algorithms (Mamdani and Sugeno) were built. As a result, numerical values are obtained - indices of evaluation of influences on the environment of the projected objects. The used decision -making method based on fuzzy logical output models is effective in evaluating the influences of industrial objects on the components of the environment, but are more difficult to formalize than numerical methods that do not require the designer of skills in a specific software environment.

Keywords: fuzzy output, uncertainty, fuzzy logic matlab, fuzzy knowledge base.

Accounting of Statistical and Expert Information in Medical Decision Support Systems

2022-12-30T06:10:21+00:00

The work is devoted to solving the actual scientific and technical problem of building a decision support system based on the implementation of the developed model of the diagnostic decision rule by means of modern information technologies. Based on the analysis of the methods used to build a diagnostic decision rule (DRU) in diagnostic decision support systems in medicine, the components of a combined DRU are proposed, which express two approaches to the formulation of a diagnostic conclusion: an objective component, which is based on the analysis of educational samples, and the subjective component, which is based on expert information about the structure of symptom complexes. The purpose of the study is the synthesis of the combined DRU based on the method of comparison with the prototype, which takes into account both the objective and subjective components of the diagnosis process. The paper developed a mathematical model of the combined DRU and substantiated the choice of its components. As an objective component, the method of comparison with a prototype was selected, in which the diagnosed conditions (a list of diagnoses in a given subject area of medicine) are represented by their prototypes in the space of signs. As a prototype of each class, the geometric center of the class grouping is calculated. Expert information on the structure of symptom complexes is formalized by presenting the symptom complex of each disease with numerical intervals of linguistic variables. Variants of taking into account expert evaluations about the structure of symptom complexes when calculating the coordinates of class prototypes (collective decision rules, weighting and summarization of evaluations) are considered. On the basis of the developed mathematical model of the combined DRU, the decision support system was designed and a comprehensive check of the developed system was performed on real medical data, which confirmed the effectiveness of the system.

Сreation of seven- and eight-factory uniform computer designgs of experiment with low discrepancies

2022-12-13T10:03:35+00:00

Scientific research on the construction of efficient uniform computer designs of experiments is being carried out quite actively, and so far it has been proven that, the best results are achieved using Sobol’s quasi-sequences, but this is not observed in all cases of their arbitrary combination. Therefore, the construction of uniform designs even for a small number of factors requires additional research to ensure acceptable indicators of their uniformity. The work is devoted to the creation of multifactorial uniform computer designs of experiments based on quasi-random Sobol’s sequences with low discrepancy rates. The object of research is the process of creating uniform computer designs of experiments. The purpose of the work is to create multifactorial, namely seven- and eight-factor uniform designs of experiments with low rates of centered and wrap-around discrepancies, as well as to study their projection properties for a different number of filling points of a single hypercube. For the purpose of cataloging, seven- and eight-factor uniform computer designs of experiments were created, the quality of which was assessed simultaneously by a visual analysis of the scattering matrix of all two-dimensional projections and quantitative indicators of the uniformity of the set of vectors that form the design in hyperspace, namely, centered and wrap-around discrepancies. The trend of maintaining low indicators of these characteristics in multifactorial spaces, which is observed with a change in the number of design points, is confirmed. The results of the study can be used in the construction of metamodels of measurement processes for cases where it is necessary to ensure a high degree of accuracy in approximating a response hypersurface of a complex shape, solving inverse problems in real time.

Applications Type-2 Membership Functions in Fuzzy Logic Systems Under Conditions of Uncertainty Input Data

2022-12-28T12:45:44+00:00

This work proposes fuzzy logics system with use of math apparatus of type-2 interval fuzzy sets. The present paper formulates the task of developing a formal approach, which would enable analyzing fuzzy systems in terms of their capability to describe uncertainties of input information using interval membership functions. In contrast with the type-1 fuzzy sets-based systems, which result in membership value in the form of a single digit, the type-2 fuzzy sets allow to obtain an interval of values of the final linguistic variable. This interval is the result of the uncertainties, which are present in the incoming data, as well as of the uncertainties, related to the nature of presentation of expertise. These peculiarities allow the interval fuzzy sets-based system to function operating with less informative incoming data as well as in case of data omission. These conditions make function of the type-1 fuzzy logical systems impossible. That is why use of the fuzzy logics systems with interval functions is seen expedient compared to the usual type-1 systems. However, such models may result in wide interval output. In case the resulting output of the model may not be used to solve a task or is not satisfactory for the developer, it is better to get to use of the three-dimension membership functions while obtaining the outcome as a linguistic interpretation. This work also describes the stages of building fuzzy knowledge base using the common rule of use of experimental data. This work also proposes an approach to evaluate the parameters of gauss type-2 membership interval functions by defining the membership functions permissible measuring ranges which allow for adequate modelling. As long as use of the interval membership function provides for the fuzzy system output value with certain interval, taking into account certain vector of input values, this work provides expert recommendations on how to evaluate the interval output.

Features of simulation of information and measurement systems character-istics of microsystem technology devices

2022-12-31T16:27:12+00:00

The necessity of simulation modeling of information and measurement systems of physical characteristics of microsystem technology devices is proven and the features of such modeling are shown. It is shown that the application of mathematical modeling methods for microsystem technology devices is not correct due to the inconsistency of classical physical laws for micro- and nano-sized objects. At the same time, it was established that the use of simulation models and modern computer tools, which can qualitatively implement these methods, allows for high-quality modeling of microsystem technology devices at a qualitatively new level in real time. It was found that the advantages of such simulation models (implemented on the basis of the MatLab Simulink mathematical processor) are the possibility of taking into account processes and phenomena that take place at the micrometric level (microcapillary phenomena, surface microcurrent and tribocharge, exodiffusion of electrons from the surface, intermolecular interaction, etc.). In the course of the simulation, simulation models of information and measurement systems of various physical characteristics (surface charge, capillary and intermolecular interaction, temperature gradient) that can occur on stationary and dynamic surfaces of microsystem components of devices were built and investigated. The verification of the obtained simulation results showed their high convergence with the experimental results (the discrepancy between the simulation results and the experimentally obtained data did not exceed 8.5%), as well as accuracy (the relative error in determining such characteristics was 4.5-11.2%) and reliability (probability of obtaining adequate results, not less than 0.996) of the obtained model. The authors suggested using the results obtained as a result of simulation modeling in the design of information and measurement systems of physical characteristics of microsystem technology devices for various purposes.

Expert system of choice of the optimum strategy for managing the production of entomophages

2022-12-18T12:50:50+00:00

The work is devoted to the development of an intelligent decision support system in the production of entomophages, in particular, an expert system for choosing the optimal production management strategy, using at the same time the methods of analysis of T. Saati hierarchies, structural synthesis and the system of computer mathematics Scilab. An expert system, an information model and an algorithm for choosing the optimal management strategy for the production of entomophages have been developed using the analysis of scientific works related to the chosen research area; the process of choosing the optimal strategy is automated using the Scilab computer mathematics system. The structure of the expert system is decomposed into: goal (choice of the optimal management strategy for the production of entomophages), criteria (production strategies: innovative transformations, changes in the organization of production, diversification of production), alternatives (strategies for managing the production of entomophages: minimization of production cost and maximization of production profit). The algorithm for choosing the optimal strategy for managing the production of entomophages consists of: definition of the goal, criteria, alternatives; construction of matrices of paired comparisons, their normalization to obtain relative weighting coefficients of criteria and alternatives; calculation of weight coefficients as average values of the corresponding rows of normalized matrices; checking columns of normalized matrices; calculation of the combined weight of alternatives; making decisions about choosing the optimal strategy based on the criterion of maximizing the combined weight. The proposed approach allows comparison of qualitatively different production strategies. Based on the calculations, it was determined that the maximization of the profit of entomophages production is the optimal management strategy, the choice is consistent in accordance with the paired comparisons of criteria and alternatives.

Algorithmical provision of fuel supply control under the conditions of incomplete information

2022-12-18T13:37:42+00:00

An indirect method for assessing the identity of power unit operating cycles is proposed. The frequency-modulated signal of the speed of rotation of the crankshaft is chosen as a source of input information. With the use of nozzles that have piezoelectric control means, the conceptual principles of software movements of hardware devices to ensure the identity of work cycles have been developed. Direct digital control and feedback control methods are used to design the hardware architecture. The torque of an individual cylinder was approximated on the basis of the Fourier transform taking into account the sequence of their work. A mechanical system with four degrees of freedom is proposed as a deterministic mathematical model of the torque circuit of the power unit. The movements of the masses of the model are described by a system of differential equations, provided that friction is taken into account. The parameters of the system are normalized and the Laplace transform under zero initial conditions is used for its solution. The information links between the torques and the measurement information signal were established using the method of determinants and the theory of signal graphs. It was found that these methods give almost identical calculation results. Algorithmic support for assessing the identity of work cycles is built on the solution of a redefined system of algebraic equations with optimization of the result based on the method of least squares. The Monte Carlo method was used as a mathematical tool for the computer simulation of random disturbances. Computer modeling of the effects of interference on the measurement information signal and on the phase delays of individual cylinders established the requirements for the metrological characteristics of the hardware

Control and management of thermo-mechanical phenomena during the mechanical processing of products made of materials with a non-homogeneous structure

2022-12-21T09:31:08+00:00

This article provides information technology on the analysis and synthesis of models for ensuring the quality characteristics of the working surfaces of products during mechanical processing, taking into account the defects of the material structure. Various micro defects are described, the development of which, under the influence of mechanical processing, leads to the appearance of cracks and their increase and, as a result, local or complete destruction. The problem of thermoelasticity for bodies weakened by inhomogeneities is solved. The probabilistic-statistical approach in increasing the accuracy of identification of technological processes of mechanical processing, development, and implementation of new, more effective methods and means of information and computer modeling is considered. The developed model takes into account the influence of inhomogeneities of technological origin (starting from the workpiece and ending with the finished product), which arise in the surface layer during the manufacture of structural elements, the analysis of which allows the creation of an information base of criteria, the implementation of which allows preventing the loss of functional properties of the responsible elements. Mathematical models of the dynamics of thermomechanical processes accompanying the mechanical processing of products from materials of the heterogeneous structure have been improved in the form of a spatially non-stationary formulation of the problem based on systems of differential equations of thermoelasticity in partial derivatives and discontinuity conditions on defects of the elastic-deformation characteristics of the processed material, which, unlike existing ones, made it possible to increase the accuracy of identification of mathematical models generally. Mathematical models of the system for evaluating the effectiveness of the functioning of technological complexes of mechanical processing have been developed, which make it possible to determine the relationship between the state parameters of the treated surfaces and the main controlling technological characteristics that provide the necessary properties of functionally gradient materials. Finally, the modeling results provide an opportunity to create effective information technology, which makes it possible to reduce the loss of functional properties of heterogeneous systems significantly.

Management of the quality characteristics of the working surfaces of complex profile products during mechanical processing

2022-12-21T10:08:12+00:00

The paper considers the temperature field model, which is formed in the surface layer of complex profile products during their processing in finishing operations. These operations are associated with defects in the surface layer of products, such as burns, cracks, and tensile stresses. Which significantly affects the reliability and durability of these parts during their operation. These defects, being local stress concentrators in operational conditions, lead to premature failure of products, even though the load on them forms stresses, the value of which does not exceed the limit values. The model is built based on the solution of the product's initial boundary value problem of thermal conductivity. Functional relationships of technological parameters with the grinding temperature obtained based on the model reflect the state of the treated surfaces for products with complex profiles and allow using appropriate techniques to eliminate burns on the treated surfaces. The study of the conditions for improving the quality of the treated surfaces by eliminating defects such as cracks and burns was carried out mainly at the level of identifying the connections of the temperature fields that are formed with technological parameters, physical and mechanical properties of the polished materials and the geometry of the products. It was established that when grinding complex profile products from a larger radius in the direction to a smaller one, the temperature increased in proportion to the angle of inclination of the treated surface. The adequacy of the built model was checked on the example of grinding conical products made of steel with known physical and mechanical characteristics, the choice of tool, and the designation of processing modes. Analysis of the simulation results shows that the temperature of the machined surface increases as the machining tool approaches a smaller diameter along the conical surface. This area of conical products' machined surface is most prone to defect formation during finishing operations. Therefore, when assigning treatment modes for such surfaces, they should be assigned with the condition that when the processing tool approaches the part of the conical surface with a smaller diameter, the temperature formed on it should not exceed the permissible values that ensure the required quality. Analysis of the results of numerical calculations of temperature fields showed sufficient accuracy according to the boundary conditions of the simulation.

Implementation of wireless mobile device drive control video systems in the MATLAB environment in the educational process

2022-12-28T12:08:30+00:00

The peculiarities of the application of computerized systems of wireless remote control of drives, which include single-board computers with Wi-Fi communication channels, are considered. The advantages and disadvantages of programming controllers for wireless control of drives of mobile devices using the Matlab environment are analyzed. The tasks of integrating the IDE programming environment for the most common single-board computers and the video interface to the Matlab environment are set. To assist programmers and developers in creating software for such devices, observation and control modules have been developed as a model for machine simulation and programming skills. Interfaces that ensure the implementation of Simulink graphical programming environment tools into the educational process are proposed. Using the example of creating and setting programs for remote wireless control of elements of robotic systems, including mobile devices for restorative medicine. This report presents a method of programming Arduino boards based on visual support of actions. The created model for visual representation of the operation of a robotic technical system with four degrees of freedom is considered. The clarity, simplicity and effectiveness of such interactive support have been demonstrated. This method is preferred because it does not require prior programming skills to write code to create complex tasks. The method is expected to lend itself well to teaching basic programming skills due to the visual elements offered. Further integration and experience of control program modules in Simulink will require the use of drop-down menus containing informational messages and links to examples. Simulation modeling and statistical evaluation will obviously become the basis for further improvement of the interface, which realizes the advantage of the board when programming using a Wi-Fi network. In addition, an important opportunity for collective problem solving opens up thanks to the transparency and convenience of teaching students programming and process modeling in the Matlab software environment.

Use of peer-to-peer networks for secured communication

2022-12-30T11:44:05+00:00

Peculiarities of the applied application of peering networks are considered (every node is equal; it can be both a client and a server). Mathematically, a decentralized network can be represented as a graph. The reasons for the emergence of peering networks are analyzed (low load on the client processor, the need to provide access to data and joint work on data). The classification of P2P networks according to three characteristics (functions, degree of centralization and method of connection) is also considered. The relevance and perspective of their application for personal communication, especially for data exchange within the company (required data security, fault tolerance and independence from Internet access) are determined.

A peering network organization model is proposed, which provides for increased data security (messages, files, audio, user settings, etc.), reliable authentication of nodes (based on a combination of manual key distribution and trust network principles), scalability of the network itself and expansion of its functional capabilities (sending text, files, support for audio, video, etc.). The software implementation should work on most modern devices and operating systems (Android, IOS, Windows, MacOS). The created model makes it possible to increase security due to the combination of various cryptographic algorithms and data exchange protocols. Data exchange is based on the Tox protocol, which involves the use of distributed hash tables and asymmetric encryption. Data transport using the Tox protocol is organized based on TCP and UDP. A graphic representation of the above-described model is given, as well as a key exchange scheme between nodes. The data is also stored at the node in a protected form, and it can be read only if the key is present.

Simulation of the Optimal Control of the Established Motion of the Oscillatory System in Random Excitation

2023-02-01T09:41:07+00:00

An approach to modeling the motion dynamics of an oscillatory system with external random excitation is proposed. This made it possible to determine the optimal control modes for the established movement of the system. In the oscillatory system under consideration, as an example of one of the types of vibration machine, random periodic force excitation is presented in the form of "white noise". Also, the motion of the system is described by stochastic differential equations. The periodic component of the excitation is represented as an expansion in terms of cosines. It is accepted that random and deterministic excitations have the same effect on the motion of the system. It is determined that in oscillatory systems excited by white noise, the value of the drift coefficients in the functional is formed only by averaging the deterministic components. This made it possible to write down the averaged dynamic programming equation and build a control synthesis. The used principle of dynamic programming determined the synthesis of control and the stochastic principle of maximum. This made it possible to build program management. The function of optimal control of the external application of the moment of forces to the suspension (executive body) is determined. This is necessary to stabilize the oscillatory system in case of random force excitation of the system as a whole. Based on the optimal control equation, special cases are considered, namely: parametric excitation includes only the first harmonic, and there is no parametric resonance; external force excitation does not contain the first harmonic, there is no external resonance; there are no external force random excitations. It is shown that for any admissible control with the help of the torque applied to the suspension, the process is reduced to diffusion. An optimal search is also performed on the trajectories (modes) of the limiting diffusion system.

Prototyping IOT project at WOKWI service

2022-12-13T11:19:14+00:00

In the development strategy of Ukraine Industry 4.0, it is stated that relevant and promising scientific and engineering services are: the creation of new software products, including 4.0 technologies; industrial automation and complex engineering; development and production of complex, low-volume, or unique products. In the conditions of mixed education, which is related to the pandemic and martial law in Ukraine, the question of how to acquire the knowledge and skills necessary for mastering the basics of developing and programming embedded systems that work with the use of smart technologies and Internet of Things technologies is quite relevant. . In the absence of access to ESP8266, ESP32 IoT modules, students are invited to simulate their work in the Wokwi cloud service. The paper considers the temperature and humidity monitoring system in the DWEET.IO cloud service on the ESP8266 IoT module and the DHT11 combined sensor. Prototyping the operation of such a system in the Wokwi service is performed on an ESP32 IoT module and a DHT22 sensor, with the simulation of data transmission to the IoT cloud service. The article provides the source codes of the temperature and humidity monitoring system program. The proposed approach allows for prototyping embedded systems that work using smart technologies and Internet of Things technologies without the presence of IoT modules and sensors. The Wokwi cloud service allows you to configure the software part of embedded systems and connect to real cloud services of the Internet of Things with the simulation of data exchange via a wireless interface using Wi-Fi technology of the 802.11g standard.

Relevance and means of preserving Russian-language search traffic of commercial sites when translating them into Ukrainian

2022-12-13T11:38:42+00:00

The risks of reducing traffic from search engines when translating commercial sites from Russian to Ukrainian have been analyzed, and measures to minimize them have been proposed. Since in the Ukrainian segment of the Internet, a significant part of Internet trading sites uses the Russian language, when they are translated into the Ukrainian language in accordance with the Law of Ukraine "On Ensuring the Functioning of the Ukrainian Language as the State", there are risks of losing traffic from search engines. Due to the fact that when searching for goods on the Internet, some users enter search queries in Russian. To assess the ratio of Russian-language and Ukrainian-language search queries, statistical data from the Google trends service was used, according to which the number of Russian-language search queries for a number of popular product items significantly exceeds the number of similar Ukrainian. In order to investigate to what extent the language of search queries affects the ranking of search results of the Google search engine, the presence of Ukrainian-language snippets in the search results for Russian-language search phrases related to trade was analyzed. According to the obtained results, this presence is insignificant and, according to the investigated semantic core, in the first hundred sites of the Google.com.ua search result, in general, it does not exceed a few percent. Therefore, in order to deliver Ukrainian-language commercial offers to the target audience that uses Russian-language search queries, when translating sites into Ukrainian, it is necessary to use additional means aimed at preserving Russian-language traffic. The considered technical solutions that allow electronic trading platforms, the profitability and competitiveness of which depends from the number of visitor transitions from search engines, in compliance with the requirements of the Law, save Russian-language traffic by adding it to the traffic for Ukrainian search queries

Synchronization of Communication Systems Based on SDR

2022-12-13T11:48:35+00:00

The development of mobile telecommunications proceeds by increasing the productivity of communication systems, increasing the speed of information transmission, expanding the frequency band, and reducing delays. A software defined radio (SDR) is a programmable transceiver that supports various wireless technologies without the need for hardware upgrades. The best development environment for SDR devices is field-programmable gate arrays (FPGAs) because they provide parallel data processing. The signal in the communication channel is distorted under the influence of many factors: conversion of the signal sampling frequency in the transmitter and receiver, frequency and phase shift of the signal in the communication channel, signal delay, effect of white noise, etc. To reduce the impact of these effects, the receiver includes a synchronization circuit. The receiver contains the following units: automatic gain adjustment; frequency offset correction; recovery of symbol synchronization; restoration of the phase of the carrier frequency; signal demodulation. To ensure fulfillment of the Nyquist criteria and reduction of intersymbol distortions, the transmitter and receiver of the communication system contain a shaping filter with a characteristic of the square root of the raised cosine. Synchronization circles provide a certain range of changes in destabilizing factors. When this range is exceeded, the parameters and quality of the communication system deteriorate. The down-converter of the sampling frequency was studied, and its frequency characteristic was obtained. It is built on the basis of half-band filters according to the quadrature scheme. The frequency shift estimation and correction algorithm is developed according to the maximum likelihood criterion. The symbol synchronization recovery subsystem is based on a phase-locked-frequency circuit (PLL). The main characteristics of the PLL: the time to reach blocking; error detected; transient behavior and traceability; bandwidth. These options depend on the field of application and expected operating conditions. The bandwidth must be sufficient to compensate for deviations between the generator frequency and the reference input signal. The study of the time required by the PLL for synchronization with the reference signal was carried out. The coefficient of bit errors and the magnitude of the error vector for various frequency shifts in the communication channel are determined. The purpose of the article is to evaluate signal distortions in the HDL implementation of the communication system based on the Xilinx Zynq-7000 development environment.