Diagnostics of the technical condition and predic-tion of accident-free guaranteed operating time of heavily loaded machines gear wheels

Problem. This article highlights the current state of diagnostics of gears on the level of accumulated fatigue damage in operation. The generalization of the known information on determination of a technical condition of separate gear wheels, especially with big modules (m> 20 mm), allows to outline prospects of development of such diagnostics of a technical condition of gear wheels directly in the course of operation. Goal. The goal of this study is to develop an algorithm for diagnosing the technical condition and forecasting a fault-free operation of the gears of heavy-duty machines. Methodology. The least squares method and the confidence interval method are used to predict accident-free guaranteed gear operation. Results. A procedure for diagnosing the technical condition of gears by measuring the hardness of the metal has been developed, which includes five main stages: selection of the device; choice of measurement scheme; selection of the number of measurements, number and relative position of measuring points; development of a design of a template for measurements; development of a device for fastening templates. When determining the accident-free guaranteed operating time on the basis of several criteria of the limit state, the final decision is made on the criterion that determines the minimum term. Originality. The method of forecasting accident-free guaranteed operating time of gears is chosen taking into account the stages of running-in and stable in linear function accumulation of damage in operation. Practical value. The use of the developed procedure for diagnosing the technical condition of the gears of gearboxes of heavy-duty machines will significantly increase the efficiency of their operation due to the transition from scheduled preventive maintenance to maintenance according to the actual technical condition.

Robust laser positioning in a mobile robot machine vision system

Problem. Laser scanning devices are widely used in Machine Vision Systems (MVS) of an autonomous mobile robot for solving SLAM problems. One of the concerns with MVS operation is the ability to detect relatively small obstacles. This requires scanning a limited sector within the field of view or even focusing on a specific point of space. The accuracy of the laser beam positioning is hampered by various kinds of uncertainties both due to the model simplifying and using inaccurate values of its parameters, as well as lacking information about perturbations. Goal. This paper presents the improvement of the MVS, described in previous works of the authors, by robust control of the DC motor, which represents the Positioning Laser drive. Methodology. For this purpose, a DC motor model is built, taking into account the parametric uncertainty. A robust digital PD controller for laser positioning is designed, and a comparative evaluation of the robust properties of the obtained control system with a classical one is carried out. The PWM signal formation by the microcontroller and processes in the H-bridge are also taken into account. Results. The obtained digital controller meets the transient process and accuracy requirements and combines the simplicity of a classic controller with a weak sensitivity to the parametric uncertainties of the drive model. Originality. The originality of the paper is in its focus on the MVS of the autonomous mobile robot developed by the authors. Practical value. The implementation of the MVS with the proposed controller will increase the reliability of obstacles detection within a robot field of view and the accuracy of environment mapping.

Method of selecting automatic control system of a motor grader

Problem. Effective use of motor graders is impossible without the use of automatic control systems, especially in modern conditions of large volumes of road construction. However, among the large number of samples of such systems, which differ in various parameters, it is impossible to make an appropriate choice without a scientifically sound approach, taking into account the set of their characteristics. It was found that these systems are characterized by a large set of parameters, with the values of some of them unknown, and the reliability of the values of many parameters is questionable, i.e. the choice must take place in conditions of fuzzy information. The methods of choosing alternatives in conditions of uncertainty described in the literature, in particular when choosing technical systems based on Analytic Hierarchy Process and fuzzy set theory, are analyzed and the latter is taken to develop a method of choosing a motor grader ACS. The goal of the work is to increase the efficiency of motor graders in road construction due to the appropriate choice of ACS. The methodology of constructing the method is the theory of fuzzy sets. The economic, technical-operational and ergonomic groups of criteria for choosing a motor grader ACS are determined and substantiated. The construction of the method was performed to select the ACS in the 3D class. As the alternatives, the systems which are the leaders of this segment were chosen. The above criteria are a set of criteria. The solution to the problem of choice is an alternative that best meets the requirements of the whole set of criteria. The results of the work are the development of a method of fuzzy multicriterion analysis for the selection of a motor grader ACS in the class of 3D systems. Originality lies in constructing the method of choosing a motor grader ACS in conditions of fuzzy information on the basis of reasonable criteria. The practical value is the fact that the use of the developed method will allow to make a scientifically sound choice of the ACS of a motor grader taking into account the whole set of criteria.

Analysis and software implementation of the modified cryptographic Vernam cipher and the Caesar cipher

Problem. Modern cryptography is a very important part of cybersecurity and confidentiality of many operations. It covers almost all parts of our lives, from e-commerce to specialized education of students. Goal. The advantage of symmetric key cryptography is that working with this method is very easy for users, as one key is used for encryption, as well as for decryption purposes, and this key must be secret and should be known only to the sender and recipient and no one else. On the other hand, public key cryptography has two keys. Unfortunately, this exposes the inherent security flaws, as the integrity of the encryption depends entirely on the password. It was decided to consider the implementation of a modified symmetric Vernam cipher that avoids these problems, and its modification and experimental studies should further strengthen data protection. Methodology. Higher mathematics, linear algebra are very important subjects. But if we want to encourage students with cryptography, we need to use all aspects of the IT cluster more effectively. Ideal for this is the implementation of algorithms and programs using programming languages. It is very important and useful for students studying Cybersecurity to illustrate where and how it is possible to create software implementations of encryption / decryption methods. Results. The article presents the analysis and implementation of the modified cryptographic Vernam cipher and Caesar cipher using a concept that combines modern programming languages and the principles of cryptography, which students study in subject-oriented specialties. Originality. An original approach to teaching Cybersecurity students by implementing ciphers using applied programming is described. Practical value. Using cryptography as a learning tool will help students develop their programming skills and effectively understand the concept of cybersecurity in real-world examples.

Analysis of the most common methods for determining the stability of energy systems

Problem. There are many methods for determining the stability of the energy system. In normal operating condition (normal rated mode), the power system must reliably ensure the consumption of electricity of normalized quality. However, in addition to the normal state, there are emergency and transient states caused by various transients. This is due to the fact that the energy system is constantly changing its parameters. Such changes are determined by variations in the amount of power produced and consumed, as well as the changes in system configuration. Goal. The goal is studying the possibilities of various methods of determining the power systems stability and drawing up the general algorithm of actions for maintenance of their stability. Methodology. When determining the stability of energy systems by the Lyapunov method, two methods can be used: the direct method and the first approximation method. Lyapunov direct method refers to differential methods. To conclude about the stability of the system we do not find a general or particular solution of differential equations, but with their help we find a mathematical function, the complete derivative of which over time allows to obtain a conclusion about the stability of the system. Results. Many methods can be used to determine whether a sustainable energy system is stable or not. The most common are the Lyapunov methods and the Moiseev method. It is determined that the direct Lyapunov method refers to differential methods. The application of the direct Lyapunov method for energy problems is limited. Currently, it can be used only for some individual cases. The method of the first approximation (Lyapunov first method) has received wider application in the solution of power problems. When applying this method, which belongs to the group of methods of full integration, the right-hand sides of the equations are decomposed into power series. Originality. It is determined that one of the perspective directions of increasing the efficiency of the mathematical device work is using the methods of the second order in modeling and optimization of operating modes of electric power systems. This allows you to increase the speed and reliability of the convergence of iterative processes. Practical value. Based on the analysis of various existing methods for solving the problems of stability of energy systems, an algorithm of actions is proposed and developed, which will help to solve the problem of stability in practice.

The method of optimizing the main technical parameters of the promising city electric buses of ONC Type

Problem. City electric buses of the ONC type, which are widely used for passenger transportation on city routes, even if the permissible gross weight is increased by 1500 kg, have significantly lower passenger capacity than the high-class buses on the basis of the bodies of which they are created. This is due to the fact that the mass of traction batteries is much greater than the mass of the power unit with all its city bus systems. Goal. The goal is determining the optimal values of the main technical parameters of promising electric buses already at the stages of development of sketch proposals or sketch projects. Methodology. The work is based on the analysis of technical parameters of city electric buses of modern designs and regulated technical requirements for high-capacity passenger wheeled vehicles, the dependences of their passenger capacity on the dimensional parameters of the body, the weight of the equipped electric bus without the weight of traction batteries and the autonomous mileage of electric buses. Results. Three variants of a technique of optimizing the parameters of the designed city electric buses on one of the set parameters – the nominal passenger capacity, average daily autonomous run or length of a body of an electric bus are developed. Originality. An algorithm for determining the optimized parameters of the designed electric buses at the stage of development of sketch proposals and sketch projects is proposed. Practical value. The proposed method provides the design of promising competitive city electric buses of ONC type, which are most suitable for use in the cities of Ukraine, with a given or maximum possible nominal passenger capacity in terms of providing a given or maximum autonomous mileage and equality of passenger capacity, determined by passenger area mass.

Peculiarities of English-teaching practice for students of electrical engineering

Problem. As engineering is a vast area of study in the world and English is a recognized language of international communication, knowledge of English is compulsory. Besides, we live in the digital age and English is the only language in latest version applications, installation guides and software instructions. Learning for students of engineering from not English-speaking countries is very important not only for their scholastic life, but also for their prospective career, mobility and successful communication. Goal. The goal of the work is to determine the features of teaching English to the students of electrical engineering, specify the role of English language for engineering students, outline the technique and methods of organizing the teaching process, look into innovative technologies of teaching. Methodology. The methodology is based on the analysis of the existing methods of teaching which are many, comparison of classical and innovative methods and analysis of the strategies of different methods. The paper emphasizes creative approach in teaching as a key to success. Results. The work provides a brief theoretical grounding and a working definition for creativity and motivation in teaching English for Specific Purposes and English as a Foreign language. It also explores the role and function of creativity in the context of the changing paradigm regarding the overall scope of the educational system in general and of the language learning in particular. Originality. The work offers combining creative methods and active strategies in fostering better language acquisition during English classes. When we see that the students are involved and motivated, it means that the strategy works. The teacher-oriented method is not currently welcomed in language teaching, and the ways to make it student-oriented are offered in the work. Practical value. The paper contains some practical advice on how a teacher can create more situations in which students can contribute, initiate, control and create. Keeping in mind the dependence of the learning success on creativity of teachers and motivation of students, new innovative methods of teaching in proper combination with theory of language can be used.

Simulation of а car parameters impact on the process of its acceleration

Goal. The purpose of the work is mathematical modeling of Daewoo Lanos passenger car acceleration dynamics. Methodology. The mathematical model is based on the methodology of E.A. Chudakov and N.A.Yakovlev. According to this method, the main factor that determines the current value of vehicle acceleration at an elementary speed section is the dynamic factor. This factor depends on the traction force, the air resistance force and the weight of the vehicle. The paper proposes formulas for determining the dynamic factor and parameters of vehicle acceleration at an elementary speed section, where gear shift takes place. The model is implemented in the MATLAB software environment. The software product allows to determine the parameters of the car during acceleration to the maximum speed when the engine is running at the external speed characteristic modes. Results Based on the results of mathematical modeling for the Daewoo Lanos car, the loads arising in the drive of the car were analyzed. It is shown that the tractive effort is mainly spent on overcoming the inertial forces, which at the beginning of the movement exceed the resistance forces of the road and air by more than 50 times. With an increase in the vehicle speed, the inertia force decreases and at a speed of 100 km / h it is only twice the other load components. It is shown that with the accepted initial data, the Daewoo Lanos car accelerates to 100 km/h in 17.7 s, which corresponds to the experimental data. The influence of the mass of the car, the rated power of the engine, the mode and time of gear shifting, the radius of the wheels, the height of the car, the coefficient of aerodynamic drag on the dynamics of acceleration of the car is analyzed. It was revealed that the vehicle weight and the nominal power of the engine affect the dynamics of acceleration from 0 to 100 km/h to the greatest extent. The influence of other parameters in the indicated speed range is not somewhat significant. The explanation of the obtained results is given. Practical value. The mathematical model presented in the work allows to determine the parameters of the engine and the car during acceleration, take into account the influence of the design and adjusting parameters of the engine and the car on these indicators, and carry out optimization studies.

Mathematical model for estimation the stability of the vehicle's motion on overturning

Problem. During the reconstruction of the circumstances of road traffic accidents with vehicles overturning, difficulties arise with determining the parameters of vehicles in the process of their overturning. This is due to the fact that the recommended calculation methods are often simplified. The main focus of such techniques is to determine the minimum speed of vehicles, which leads to their overturning. In fact, the speed of vehicles before overturning can be significantly higher. Goal. This paper is dedicated to developing mathematical model of overturning vehicles that makes possible to determine not only the conditions for overturning vehicles, but also other parameters of the vehicle movement in the process of overturning. Methodology. The overturning of the vehicle occurs as a result of the action of inertial forces after collision with an immovable side obstacle. In this case, the moment from the force of gravity of the vehicle keeps it from overturning. In the process of overturning the vehicle, the moment from the force of gravity decreases due to the decrease in the arm of the force of gravity. To compile a mathematical model, the basic equation of dynamics during rotational motion was used. The mathematical model of a vehicle overturning is written in the form of a nonlinear homogeneous second order differential equation. An analytical solution of this equation is obtained. Results. Developed mathematical model makes possible to determine not only the conditions for overturning vehicles, but also other parameters of the vehicle movement from the moment the center of mass begins to rise to the moment of its maximum rise in the process of overturning. For a particular case, when the critical speed of a vehicle during its overturning is determined, the developed mathematical model fully corresponds to the mathematical model based on the law of conservation of energy. For a specific vehicle, numerical results were obtained that fully correspond to the physics of the overturning process.

Functional scheme of the transformer-rectifier unit of the centrifugal oil cleaning installation

Annotation. Problem. The reduction of reliability, economical and mass-dimensional indicators is one of available ways for centrifugal cleaning transformer olives installations, which based on electric drives with icreased frequency. In addition to the development and calculation of the power scheme of the installation, the issue of developing an calculation power supply system from the industrial power system is relevant. In this case, the task of developing and researching a voltage and frequency converter, which is an intermediate link between the industrial power system and the centrifugal oil cleaning installation and provides the specified parameters of electricity, requires the solution of additional partial problems. Goal. The goal is to develop and study the functional scheme of the transformer-rectifier unit with an automated output voltage control system for the installation of centrifugal cleaning of transformer oil. Methodology. Analytical methods of research, methods of the theory of electric machines and electric drives, and also methods of calculation of transfer functions of elements of the automated control systems and their dynamic characteristics are used. Results. The structural scheme of the transformer-rectifier unit with the automated control system of the output voltage of the installation for cleaning transformer oil on the basis of the electric drive of the increased frequency is developed. Calculations of transfer functions of elements of the offered automated control system of the transformer-rectifier unit are executed and its dynamic characteristics are investigated. Originality. The scheme of the transformer-rectifier unit for installation of centrifugal cleaning of transformer oil with the electric drive of the increased frequency is developed and investigated. Practical value. The introduction of centrifugal transformer oil cleaning units with a high-frequency electric drive will increase the reliability, economy and weight of such units. The calculations allow us to draw conclusions about the compliance of the proposed scheme of the transformer-rectifier unit with an automated voltage control system for reliability and dynamic characteristics of the requirements for the secondary power supply of the centrifugal oil cleaning installation.