Showing papers in "Science and Transport Progress. Bulletin of Dnipropetrovsk National University of Railway Transport in 2020"

Gondola cars dynamics from the action of longitudinal forces

Abstract: Purpose . The aim of the work is to study the influence of longitudinal quasistatic tensile and compressive forces in gondola cars arising at stationary and transient modes of train movement on their main dynamic indicators and interaction indicators of rolling stock with a rail track, taking into account the possibility of speed increasing. The relevance of this study is related with the need to control the longitudinal forces arising during stationary and transient modes of train movement, with increasing speeds, masses and lengths of trains, especially freight ones, increasing the locomotives` power. Methodology . The main method for studying the dynamic loading of a gondola car on typical three-element bogies is mathematical and computer modeling of the interaction of rolling stock and track structure based on the model of spatial vibrations of freight cars` couplings. In a theoretical study, the influence of quasistatic longitudinal tensile and compressive forces is considered depending on the change in speed and the force value on the tension of 1 MN; 0.5 MN; 0 and before compression of 0.5 MN; 1 MN. Findings . As a result of theoretical studies and after modeling, taking into account the processes of oscillation of gondola cars under the action of quasistatic longitudinal forces limited by norms to ± 1MN (100 tf), the dependencies of the main parameters normalized by technical documentation are obtained taking into account the value of the movement speed. Originality . The influence of longitudinal compressive and tensile forces on the dynamic loading of a freight car is studied in order to solve the problem of forecasting the dynamics of rolling stock, taking into account the value of the speed along curved track sections. Practical value . Application of the results obtained can increase the stability of freight rolling stock and the strength of the railway track, which in turn will remove some existing restrictions on permissible speeds and increase the technical speed of trains. The obtained dependencies of the main normalized indices on the longitudinal quasistatic force will make it possible to predict the development of deviations and prevent their transformation into the dangerous ones for train movement.

Computer simulation of biological wastewater treatment processes in aerotanks with plates

Abstract: Purpose. Efficiency determination of the aeration tank at the stage of design or reconstruction of bioreactors in which biological wastewater treatment is carried out requires the use of special mathematical models and calculation methods. The main purpose of the article is to develop CFD models for evaluating the operation efficiency of aeration tanks. Methodology. A numerical model has been developed for the computer calculation of the biological wastewater treatment process in aerotanks, taking into account hydrodynamics. The model is based on two-level mass conservation equations for the substrate and activated sludge and the velocity potential equation. The process of biological transformation of the substrate is calculated based on the Monod model. For the numerical integration of the mass transfer equations of activated sludge and substrate, the alternating-triangular difference splitting scheme is used. In this case, the basic equations are divided into two equations of a more simplified form. For the numerical integration of the equations for the velocity potential, it is split into two one-dimensional equations. Further, each equation is solved according to explicit scheme. For the numerical integration of equations that describe the process of substrate transformation based on the Monod model, the Euler method is used. Findings. The software implementation of the constructed numerical model has been carried out. The results of a computational experiment on the study of the wastewater treatment process in an aeration tank with plates are presented. This leads to the conclusion that the quality control of wastewater treatment in aeration tanks is possible with the help of plates. Originality. A multivariate CFD model has been developed, which makes it possible to quickly assess the efficiency of the aeration tank. A feature of the model is the ability to evaluate the operation of the aeration tank, taking into account its geometric shape and location of additional plates in the construction. Practical value. The constructed numerical model can be used during calculations in the case of designing aeration tanks, or in determining the efficiency of wastewater treatment under new operating conditions.

Detection of attacks on a computer network based on the use of neural networks complex

Abstract: Purpose. The article is aimed at the development of a methodology for detecting attacks on a computer network. To achieve this goal the following tasks were solved: to develop a methodology for detecting attacks on a computer network based on an ensemble of neural networks using normalized data from the open KDD Cup 99 database; when performing machine training to identify the optimal parameters of the neural network which will provide a sufficiently high level of reliability of detection of intrusions into the computer network. Methodology. As an architectural solution of the attack detection module, a two-level network system is proposed, based on an ensemble of five neural networks of the multilayer perceptron type. The first neural network to determine the category of attack class (DoS, R2L, U2R, Probe) or the fact that there was no attack; other neural networks – to detect the type of attack, if any (each of these four neural networks corresponds to one class of attack and is able to identify types that belong only to this class). Findings. The created software model was used to study the parameters of the neural network configuration 41–1–132–5, which determines the category of the attack class on the computer network. It is determined that the optimal training speed is 0.001. The ADAM algorithm proved to be the best for optimization. The ReLU function is the most suitable activation function for the hidden layer, and the hyperbolic tangent function – for the output layer activation function. Accuracy in test and validation samples was 92.86 % and 91.03 %, respectively. Originality. The developed software model, which uses the Python 3.5 programming language, the integrated development environment PyCharm 2016.3 and the Tensorflow 1.2 framework, makes it possible to detect all types of attacks of DoS, U2R, R2L, Probe classes. Practical value. Graphical dependencies of accuracy of neural networks at various parameters are received: speed of training; activation function; optimization algorithm. The optimal parameters of neural networks have been determined, which will ensure a sufficiently high level of reliability of intrusion detection into a computer network.

3D Modeling of Biological Wastewater Treatment in Aeration Tank

Abstract: Purpose. The main purpose of the article is to develop a 3D CFD model for modeling the process of biological wastewater treatment in an aeration tank. Methodology. For mathematical modeling of the process of biological wastewater treatment in the reactor, taking into account the flow hydrodynamics, geometric shape of the aeration tank, convective-diffusion transfer of the substrate and activated sludge, a 3D CFD model was built. The model is based on the three-dimensional equation of motion of an ideal liquid and the equation of mass conservation for the substrate, activated sludge. The field of sewage flow rate in the aeration tank is calculated based on the velocity potential equation. The process of biological transformation of the substrate is calculated on the basis of the Monod model. The splitting scheme was used for numerical integration of the equations of convective-diffusion transfer of activated sludge and substrate. The splitting is carried out in such a way to take into account the transfer of substrate (activated sludge) in only one direction at each step of splitting. The calculation of the unknown value of the substrate (activated sludge) concentration is carried out according to an explicit scheme. The Richardson method is used to numerically integrate the three-dimensional equation for the velocity potential, and the unknown value of the velocity potential is calculated by an explicit formula. Euler's method is used for numerical integration of equations describing the process of substrate transformation and change in activated sludge concentration (Monod model). Findings. The software implementation of the constructed 3D CFD model is carried out. A description of the structure of the developed software package is provided. The results of a computer experiment to study the process of wastewater treatment in an aeration tank with additional elements are presented. Originality. A new multifactor 3D CFD model has been developed, which allows quick assessing the efficiency of biological treatment in an aeration tank. Practical value. The constructed 3D CFD model can be used to analyze the efficiency of the aeration tank under different operating conditions at the stage of sketch design of wastewater treatment systems.

Emergency Burning of Solid Rocket Propellant: Damage Risk Assessment to People in the Workplace

Abstract: Purpose. This work includes the development of a computer model to calculate the risk of thermal damage to people in the shop in case of emergency burning of solid rocket propellant. Methodology. To calculate the temperature field in the shop in order to determine the zones of thermal damage to workers in the building, the equation expressing the law of energy conservation was used. Based on this modeling equation, the temperature field in the shop is calculated in the presence of a source of heat emission – burning solid rocket propellant. To calculate the velocity field of air flow in the shop, taking into account the location of obstacles in the path of heat wave propagation, we used the model of vortex-free air motion – the equation of the velocity potential. A two-step finite difference scheme of conditional approximation is used to numerically solve the equation for the velocity potential. A difference splitting scheme was used to numerically solve the energy equation. At the first stage of construction of the difference splitting scheme of the two-dimensional energy equation into the system of one-dimensional equations is performed. Each one-dimensional equation allows you to calculate the temperature change in one coordinate direction. The point-to-point computation scheme is used to determine the temperature. When conducting a computational experiment, the air exchange in the building is taken into account. The risk assessment of thermal damage to personnel in the building is performed for different probabilities of the place of emergency combustion of solid rocket propellant. Findings. Using numerical model prediction of the potential risk areas of thermal damage to staff in the shop for a variety of emergency situations was performed. Originality. A computer model for rapid assessment of the potential risk of damage to people in the shop in case of emergency burning of solid rocket propellant was constructed. Practical value. The authors developed a code that allows you to quickly simulate the temperature fields formation in the shop in case of emergency burning of solid rocket propellant and to identify potential areas of thermal damages to workers based on this information. The developed computer program can be used to assess the risk of thermal damage in the chemical industry in case of emergency.

Дослідження двох підходів до виявлення мережних атак із використанням нейромережної технології

Abstract: Purpose. At the present stage, network attack detection systems based on the following neural networks are most often offered: multilayer perceptron, Kohonen network or self-organizing map and their combinations. The efficiency problem of two approaches to detect attacks on a computer network using neural network technology based on the normalized data of the open NSL-KDD database is considered. Methodology. As an architectural solution to the network attack detection system, it is proposed to consider the following approaches: based on one neural network determining the attack class (first approach) and an ensemble of five neural networks (second approach), which at the first stage determines the attack category (DoS, Probe, U2R , R2L), and in the second stage, the attack class belonging to a certain category. Findings. Based on the neural networks created in the MatLAB program, a study was conducted of their error on the length of the training sample using various training algorithms: Levenberg-Marquardt; Bayesian Regularization; Scaled Conjugate Gradient with different numbers of hidden neurons (minimum, average and maximum). Certain optimal parameters of neural networks with two approaches were determined. Originality. In the course of conducting experiments with various approaches, the results obtained were: TP (True Positive); FP (False Positive); FN (False Negative); TN (True Negative), based on which the following indicators were calculated for assessing the quality of solutions: correct determination of network attacks; false positives; reliability; accuracy and completeness, which prove the feasibility of using an ensemble of neural networks (second approach). Practical value. On the created neural networks with various approaches, studies were conducted: the operating time of neural networks; errors of the first kind; errors of the second kind. According to the results of the first study, the average operating time of an ensemble of neural networks is 0.92 s, and the operating time of a neural network (according to the first approach) is 2.21 s. According to the results of the second study, the error of the first kind using an ensemble of neural networks is 2.17%, and using the neural network (the first approach) – 7.39%. According to the results of the third study, the error of the second kind using an ensemble of neural networks is 3.91%, and using the neural network (the first approach) – 6.96%, which is confirmed by the efficiency of using an ensemble of neural networks (second approach).

Organizing Wireless Network at Marshalling Yards Using the Bee Method

Abstract: Dep. «Electronic Computing Machines», Dnipro National University of Railway Transport named after Academician V. Lazaryan, Lazaryana St., 2, Dnipro, Ukraine, 49010, tel. +38 (056) 373 15 89, e-mail viknikpakh@gmail.com, ORCID 0000-0002-0022-099X Dep. «Electronic Computing Machines», Dnipro National University of Railway Transport named after Academician V. Lazaryan, Lazaryana St., 2, Dnipro, Ukraine, 49010, tel. +38 (056) 373 15 89, e-mail olkdi@outlook.com, ORCID 0000-0002-7134-9416

The problem of a lack of material behaviour data for risk assessment

Abstract: Purpose. The main purpose of this work is to provide theoretical support for the need to expand data on changes in the material behaviour under dynamic loads when railway track risk assessment over time due to railway track elements deformability. Methodology. For the research, an original model of railway track design described using the original method based on the ability of elastic waves to propagate energy of power pulses in space and time, as well as a model describing materials as discrete substances were used. Findings. It has been established that the properties of the material affect the deformability of the elements and the design of the railway track; the main parameter in the study of deformability processes is time; material, as a substance, consists of atoms and molecules, and therefore is not continuous; internal physical processes determine changes in the behaviour of the material of an element. Originality. It has been proposed to develop classifications of changes in the physical properties of materials according to the probability of irreversible deformations and the impossibility of deformations, as well as classifications of changes in the mechanical properties of materials according to the probability of the defect appearance and changing the material structure. Practical value. The ability to simulate analytically any physical processes occurring inside elements due to the proposed method allows combining the influence of mechanical and physical effects into a single calculation. This enables to assess the probability of appearing defects in elements under certain dynamic loads when assessing the railway track risk over time due to railway track elements deformability.

Methodology for engineering calculation of stability coefficient against wheel climbing on the rail

Abstract: Purpose. One of the indicators of the track and rolling stock interaction, non-observance of which can result in a traffic safety violation, namely to derailment, is a condition for ensuring stability against the wheel flange climbing onto the rail head. The aim of this work is to create a methodology for practical engineering calculation of the resistance coefficient against the wheel flange climbing onto the rail head. The described methodology will have complete information both from calculation formulas and from reference materials, to eliminate the need to attract additional sources and special software. Methodology. The main objective of the implementation of this purpose is to bring the calculation of horizontal forces to the engineering level. Due to the complexity of the interaction process between the track and the rolling stock and the need to take into account a large number of factors that have an effect on the result, as a rule, complex dynamic models are used to determine horizontal forces. A possible solution lies in the assumption that for a specific type of rolling stock, the horizontal force can be calculated by linear dependence on the value of the unbalanced acceleration. For this, an analytical technique for calculating horizontal forces was used. Findings. The authors determined the missing coefficients for calculating the horizontal force depending on the unbalanced acceleration for some types of shunting locomotives and for a freight car taking into account its load level. Originality. In the work, scientific and practical approaches for the interaction analysis of the track and rolling stock in the horizontal plane acquired further development. Practical value. The proposed step-by-step methodology for calculating the stability coefficient makes it possible at the engineering level to carry out a practical analysis of ensuring the safety margin against the wheel flange climbing onto the rail head, which is necessary when investigating the causes of rolling stock derailment and for a number of other tasks related to movement in curved track sections.

Development of car traffic volumes organization methods in the russian empire and in the ussr

Abstract: Purpose. The main purpose of this article is to study the development of methods for organizing car traffic volumes into trains at the railways of the Russian Empire and the USSR. Methodology. The studies were carried out based on an analysis of literary sources and methods of the theory of organization of operational work of railways. Findings. The methods for organizing car traffic volumes have gone a significant development path under the influence of changes in the working conditions of railway transport, the formation of control technology and mathematical methods of optimization. The emergence of scientific methods for organizing car traffic volumes in trains dates back to the times of the Russian Empire. A modern approach to the organization of car traffic volumes is based on the plan for the train formation, developed in the USSR in 1931–1945. The goal of the implementation of the train formation plan was to reduce railroad expenses for cargo transportations. The conditions for the implementation of this approach is that the railways are vertically integrated: they simultaneously operate the railway infrastructure, and are the carriers transporting goods in their cars, while there is no competition between the transport modes for freight traffic volumes. The formation of modern methods for solving the problem of organizing car traffic volumes was mainly performed in 1945–1952. The basis of these methods is the separation of the organization of car traffic volumes into separate subtasks and their sequential solution in a deterministic and static setting. In practice, the organization of car traffic volumes at the railways of the USSR was solved in the 1970–1980s using a computer. The transition of Ukraine to a market model of the economy has led to a significant change in the working conditions of railway transport, which requires a review of the principles of organizing car traffic volumes into trains. Originality. For the first time, based on a historical analysis of the development of methods for organizing car traffic volumes at the railways of the Russian Empire and the USSR, connections were established between the working conditions of railway transport and methods for organizing car traffic volumes into trains. Practical value lies in the fact that they indicate the need to change in Ukraine the organization of car traffic volumes in accordance with the current working conditions of railway transport and the chosen direction of reforming the railway transportation market.

Detection of residual stresses in coatings obtained by the method of arc metallization with a pulsating spraying flow

Abstract: Purpose. The authors propose to develop a mathematical model for the calculated determination of residual stresses in arbitrary layer of a thermal gas coating based on the change magnitude in the base geometry (sample deflection) and the variation law of the layer thickness derivative, further regulation of these stresses by changing the technological parameters of spraying for each type of sprayed coating. Methodology. Based on known works on stress detection of in welded joints, the approach of determination of samples deflection after layer-by-layer spraying was developed. These deflection parameters are the basis for the developed mathematical model of influence on the stress state. The data on the study of the main types of residual (internal) stresses, as I type, distributed in the volume of the whole part (sample) with coating, and II type, localized in the volume of sprayed particles, are systematized. Findings. We presented investigations of the residual stresses arising in the applied layer, the magnitude and nature of the distribution of which depend on the type, base and sprayed materials, methods and parameters of spraying, the rigidity of the part, and other factors. The important role of evaluating residual stresses in a thermal gas coating by the calculation method is shown in connection with the complexity of the experimental determination of the kinetics of stress development in the coating-base composite. Originality. The authors of this work, on the basis of the first created mathematical model and software product Mathcad-Prime 6 2020, conducted a study of the level and principles of the formation of residual stresses in the coating during gas-thermal layer-by-layer spraying with various material, including the possibility of using a pulsating spraying air flow. Analytical studies have shown that the attention in the literature over the past five to seven years has been paid only to the study of residual stresses and deformations in welded joints, and only the growing interest in spraying technology opens up wide possibilities for studying the formation of stress fields in a thermal gas coating. Practical relevance. The results obtained in this paper confirm the formation of residual stresses in coatings and can be used as computational programs to solve design tasks, as well as for educational purposes during experts training in engineering fields.

Dynamic Properties of One-Storey Industrial Building

Abstract: Purpose. Recently, there has been a growing demand in Ukraine for the reuse of industrial buildings that have not been in exploitation for a certain period of time. At the same time, there are frequent cases when new technological equipment transfers significant dynamic loads to existing structures over a long period of time. Since the available data regarding the dynamic properties of industrial buildings are now practically absent, the main goal of the studies made by the authors is to evaluate and analyze own dynamic characteristics of a one-storey industrial building. Methodology. To achieve this goal, it was necessary first to choose the type of industrial building, which is common enough for the formulated conditions of the reuse possibility. A one-storey unheated industrial building with three purlins (purlins 15 + 15 + 6 m) with a steel supporting frame was taken as such a building. In the course of research, the cross sections of the main load-bearing elements were varied, as well as the schemes of their connection with each other. The calculations were carried out by the finite element method based on the Lira for Windows project complex. Findings. The obtained frequency spectra of the own dynamic characteristics for the main bearing structural elements of an industrial building of the type in question are in the range up to 30 Hz. Also, during the research, dependencies were obtained for changing this range for various cases of design decisions of the building. Originality. The research results presented in the publication make it possible to evaluate the range of the own dynamic characteristics of single-storey multipurlined unheated industrial buildings with the traditional structural solution of the steel frame. Practical value. The resulting range of the own dynamic characteristics of the industrial building of the type in question is quite dangerous for human health. The most unfavorable is the oscillation form of the columns, which actually involves the entire structural frame. Therefore, in the course of research, a special method was developed and tested to stabilize such vibrations «on the base» using flexible ropes.

Визначення міцності несучої конструкції вагона-платформи зчленованого типу з круглих труб

Abstract: Мета. Це дослідження спрямоване на визначення показників міцності несучої конструкції вагона-платформи зчленованого типу з круглих труб. Методика. Створено комп’ютерну модель несучої конструкції вагона-платформи зчленованого типу з круглих труб. Для дослідження динамічної навантаженості несучої конструкції вагона-платформи проведено математичне моделювання. Розрахунок виконано в плоскій системі координат. До уваги взяті коливання посмикування, галопування та підскакування. Розв’язок диференціальних рівнянь руху здійснено в програмному забезпеченні MathCad. Проведено розрахунок на міцність несучої конструкції вагона-платформи зчленованого типу. Результати. Встановлено, що прискорення, які припадають на несучу конструкцію першої секції вагона-платформи, складають 38,2 м/с², а другої – близько 37,5 м/с². Отримані величини прискорень ураховано для визначення показників міцності несучої конструкції вагона-платформи зчленованого типу. Розрахунок проведено за методом скінченних елементів у програмному забезпеченні CosmosWorks. Ураховано, що кожна секція вагона-платформи завантажена двома 20-футовими контейнерами. Результати проведених розрахунків дозволили зробити висновок, що максимальні еквівалентні напруження виникають у консольних частинах хребтової балки та складають близько 200 МПа, тобто не перевищують допустимі. Максимальні переміщення у вузлах конструкції зафіксовано в середніх частинах секцій та складають 3,8 мм, максимальні деформації складають 2,3∙10 -3 . Наукова новизна . Розроблено комп’ютерну модель для визначення міцності несучої конструкції вагона-платформи зчленованого типу з круглих труб. Модель дозволяє визначити показники міцності несучої конструкції вагона-платформи за поздовжньої навантаженості конструкції. Практична значимість. Проведені дослідження сприятимуть підвищенню ефективності експлуатації комбінованих перевезень та створенню рекомендацій щодо проєктування сучасних конструкцій вагонів-платформ зчленованого типу.

Вплив на динаміку вантажних вагонів поперечного зміщення візків

Abstract: Purpose The work is aimed at determining the influence of the lateral displacement of a freight car bogie, taking into account the value of the movement speed on its main dynamic indicators and interaction indicators of the rolling stock and the track Methodology The quantitative assessment of dynamic indicators was obtained by the method of mathematical and computer modeling The design scheme of the car takes into account the interaction peculiarities of cars as part of the train: the possibility of all modes of body vibration in space, the transmission of longitudinal force from neighboring cars in vertical and horizontal directions, taking into account the technical condition of individual parts of the car and their design features, as well as various operating conditions Findings During the research, a mathematical model of a coupling of five freight cars was applied to study the dynamic loading of a gondola car and a track Main dynamic and interaction indicators of the rolling stock and the track in case of transverse bogie displacement when moving along curved track sections assessment were assessed The maximum possible values of the lateral displacement of the freight car bogie were substantiated Originality The mathematical model of the coupling of freight cars in the train has been improved In the calculation schemes describing the vibrations of the cars, the peculiarities of the freight car bogies, lozenging of the bogie side frames are taken into account The model makes it possible to study the effect of changing rotation angle of the central axis of the car body, which in turn leads to the lateral displacement of bogies relative to each other, on the main dynamic and interaction indicators of the rolling stock and the track For the first time, the influence of transverse displacement of the bogie was investigated, taking into account the wear of its parts and assemblies when moving on track sections with unevenness Practical value The calculation results can be used to assess the influence of the bogie transverse displacement on the dynamic qualities of the rolling stock and interaction indicators of the rolling stock and the track, taking into account the wear of parts and units of the bogie when moving in straight and curved track sections with irregularities The application of the results obtained will contribute to an increase in the stability of freight rolling stock in the conditions of increasing travel speeds, which in turn will allow developing technical conditions for the implementation of resource-saving technologies for transporting goods that meet the safety requirements of train traffic

Analysis of layout schemes of sleeping cars

Abstract: Purpose. The purpose of the work is the development, analysis and selection of layout schemes for passenger cars according to the number and location of enclosed platforms and sanitary facilities for creating promising competitive sleeping cars of various comfort levels and assessing the prospects of mastering their mass production in terms of ensuring maximum capacity. Methodology . An analysis of the layout schemes and planning of existing sleeping cars of various European manufacturers and layout schemes of promising cars in terms of size, number and placement of enclosed platforms and sanitary facilities was carried out according to the proposed criteria and performance for the efficiency of design solutions and the comfort of cars. Findings . Designed layout schemes of promising sleeping cars equipped with two or one enclosed platform and three or four sanitary facilities for general use – lavatory rooms, lavatory rooms combined with shower racks or shower cabins and separate shower cabins. A technique is proposed for assessing the efficiency of the developed design solutions and the comfort of promising sleeping cars in terms of the number, purpose and location of sanitary facilities and the ease of their use by passengers. Based on the analysis of the proposed layout schemes, their optimal variants were selected, recommended for creating promising competitive sleeping cars of a substantially higher comfort level. Originality . For the first time, an analysis of existing and new layout schemes of passenger sleeping cars by the number and placement of enclosed platforms and the number, types and placement of public sanitary facilities based on the developed methodology for an objective assessment of the efficiency of layout solutions, levels of car comfort and ease of their use by passengers. Practical value of the work lies in the possibility of a reasonable choice already at the stage of development of outline proposals for optimal layout schemes for creating promising competitive sleeping cars of different classes of increased comfort levels.

Formation of Carbon Steel Structure During Hot Plastic Deformation

Abstract: Purpose. The main purpose of the work is to determine the peculiarities of the development of recrystallization processes of carbon steel austenite depending on the degree of hot plastic deformation and to develop proposals for improving the structural state of the metal of the railway solid-rolled wheel. Methodology. Two carbon steels of a railway wheel with a minimum and maximum carbon content of 0.55 and 0.65 % and other chemical elements within the grade composition of the steel 60 were used as research material. Samples in the form of cylinders with a diameter of 20 mm and a height of 40 mm were heated in a muffle furnace, exposed for a certain time to equalize the temperature across the cross section of the sample. After that, the samples were subjected to hot compression on Instron type test machine. The temperature interval of hot compression of the samples was 950–1100 oС, with deformation degrees in height in the range of 10–40%. The strain rate was 10-3–10-2sec-1. A standard etching was used to detect the boundaries of the austenite grains. Structural studies were performed using Epikvant type light microscope at magnifications sufficient to determine the structure of austenite grains. The grain size of austenite was determined by the methods of quantitative metallography. Findings. In the case of hot compression of the railway wheel blank, increasing the concentration of carbon atoms only within the grade composition of the steel is sufficient to increase the average austenite grain size, which confirms the proposals to limit the carbon content in the metal of railway wheels. The formation of a certain degree of austenite structural heterogeneity at the cross section of the rim or hub of the railway wheel is due to a change in the development mechanism of recrystallization processes depending on the deformation value. Under conditions of the same degree of hot plastic deformation, the replacement of one-time compression by fractional one is accompanied by a violation of the conditions of formation of the recrystallization nucleus. As a result of the specified replacement of the scheme of hot plastic deformation we obtain reduction in the austenite grain size. Originality. Based on a study of the development of collective recrystallization processes during the hot compression of carbon steel of the railway wheel, it was determined that the increase in carbon content contributes to the austenite grain increase. After hot compression of the wheel blank, the structural inhomogeneity of austenite that occurs is determined by a change in the mechanism of recrystallization processes development. During deformations above the critical degree, the recrystallization nuclei are formed and successively grow, which leads to the structure refinement. In the case of deformations below the critical value, the growth of austenite grains occurs according to the coalescence mechanism, according to which fragments of boundaries with large disorientation angles consistently disappear. Practical value. For austenite grain refining in massive elements of solid-rolled railway wheel we offer to replace one-time hot compression by fractional one.

Improving the methodology for assessing the train traffic safety at the railway

Abstract: Purpose. Despite the fact that the current methodology in Ukraine for assessing the train traffic safety at the railway does not provide a real and adequate picture, and foreign experience does not open up the possibility of a similar solution to the problems at Ukrainian railways, the goal has been set to improve the methodology for assessing the train traffic safety at the railway. Methodology.To improve the methodology for assessing the train traffic safety at the railway during a technical audit, the use of four indicators is proposed: the number of accidents for which losses are accrued; number of casualties; the number of traffic accidents that occurred during the year, but their consequences are not related to financial losses; number of violations identified by traffic safety auditors. Findings.The author has improved the methodology for assessing the train traffic safety at the railway. At the same time, four indicators were introduced in the methodology to calculate the train traffic safety at the railway. The ranking of these indicators was also performed. Using statistical data on the adopted indicators, a mathematical model was obtained for the integral assessment of train safety, on the basis of which a comparative assessment of traffic safety was performed at Ukrzaliznytsia JSC. As a result, it should be noted that the dynamics of the state of traffic safety in 2015-2018 has a different picture compared to the usual number of traffic accidents in Ukrzaliznytsia JSC. An improved methodology for assessing the state of train traffic safety at the railway allows us to perform adequate calculations and establish the real state of traffic safety during a technical audit. Originality. The author has improved the methodology for assessing the train traffic safety at the railway, which can be applied during the technical audit. Practical value. The improved methodology makes it possible to assess the general level of train traffic safety and establish real threats and risks in the process of technical audit, which, in the future, can be eliminated when developing appropriate measures and actions.

Modern trends in the development of transport and logistics systems

Abstract: Purpose. At the present stage, for the normal functioning of the economy, it is necessary to maintain a balance of economic interests for consumers of transport services and transport itself. Therefore, the aim of this work is a detailed study and analysis of the current development level of transport and logistics systems, as well as the prospects for their further development. Methodology For analyze the work of modern transport and logistics systems, a set of methods of economic and mathematical modeling was used, including an element-by-element examination of the transport and logistics system, determining the demand for each of its elements among consumers, the level of corresponding costs, differentiating transport services, etc. Based on the obtained analytical data, the behavior of the transport and logistics system is modeled depending on the specific conditions of its functioning and possible features that accompany it. This allows you to consider various options for using modern technologies in the operation of the transport and logistics system and evaluate the potential benefits. Findings. The application of the logistics principles is aimed at improving the transport services based on the latest transport technologies, which allows using different types of transport, improving information interaction between participants in the transportation process, etc. The development of transport and logistics systems in the Republic of Belarus is also determined based on the Republican expeditionary unitary enterprise BELINTERTRANS – Transport and Logistics Center of the Belarusian Railway. The concept of transport and logistics systems is disclosed. Based on a study of the Belintertrans enterprise, the effectiveness of introducing such technologies as FLEXE technology and the GLONASS fuel consumption control system for the development of transport and logistics systems is examined. Originality. Based on the study of methodological sources and scientific developments in the field of development of transport and logistics systems, several options are proposed for introducing new and more advanced information technologies into the activities of transport and logistics centers. Practical value. The result of applying these technologies is, first of all, cost reduction in the logistics system, as well as increasing the competitiveness of the enterprise, increasing its profits and maximizing customer satisfaction. Since in the transport and logistics system, to satisfy the needs of the client (providing services to consumers and producers of goods), the functions of transportation, storage, distribution, etc. are implemented, the use of information technologies in any of them will increase the stability and efficiency of the system.

Совершенствование технологии работы сортировочных станций на основе дистанционного акустического зондирования

Abstract: Цель. Основной целью этой работы является анализ действующих систем автоматического управления роспуском составов на сортировочных станциях, с определением их недостатков и обоснованием необходимости цифровой конкретизации координат положения вагонов и локомотивов на путях надвига и в сортировочном парке с учетом инвентарных номеров подвижных единиц. Методика. Исследованы принципы влияния низкочастотных физических воздействий на длину отраженной волны в волоконно-оптическом кабеле, уложенном вдоль рельсов. Обоснована принципиальная пригодность оптоволоконных технологий для распределенного акустического зондирования DAS (Distributed Acoustic Sensing). Дана оценка эффективности применения системы DAS для непрерывного слежения за перемещением вагонов и локомотивов, мониторинга свободности и занятости путей на сортировочных станциях. Использована методика моделирования и технологии настройки рефлектограмм для проведения измерений в волоконно-оптическом кабеле. Проанализировано использование координатно-временной информации для контроля местоположения горочного локомотива, обеспечивающей автоматическое позиционирование подвижных единиц. Результаты. Определение координат «окон» в сортировочном парке имеет важное значение для сокращения непроизводительных потерь времени по осаживанию или подтягиванию вагонов, а также излишнего перепробега горочных локомотивов. Полученную информацию от напольных датчиков системы DAS о количестве и типах вагонов в движущемся отцепе можно использовать для выявления «чужаков» на путях сортировочного парка. В этом случае непрерывное слежение за отцепом повысит достоверность информации в подсистеме управления прицельным торможением на спускной части сортировочной горки. Для автоматического определения инвентарных номеров вагонов с помощью специальной компьютерной программы обработки видеоизображений можно использовать автоматизированную систему контроля инвентарных номеров (АСКИН). Для этого программный аппаратный комплекс необходимо дополнить драйвером чтения и записи потоков информации с видеокамер при контроле поездов на входе в парки прибытия сортировочных станций. Научная новизна. Оснащение путей сортировочных станций волоконно-оптическими кабелями и аппаратурой системы DAS позволит повысить оперативность управления расформированием и формированием составов в режиме реального времени за счет точного определения координат нахождения локомотивов и вагонов на станционных путях. Практическая значимость. Комплексная система автоматического управления сортировочным процессом (КСАУ СП), дополненная системами DAS и идентификации инвентарных номеров вагонов, обеспечит ведение полноценной цифровой поездной и вагонной модели сортировочного процесса на надвижной и спускной частях горки и в сортировочном парке.

Study of negative influence of petroleum products on metal elements of railway infrastructure

Abstract: Purpose. The main purpose of the work is to improve the safety of railway transport operation. The implementation of this purpose is provided by assessing and preventing the negative influence of petroleum products on the structural elements of the railway infrastructure. Methodology. The main criterion for assessing the residual life of technical elements of equipment is their strength characteristics. One of the key factors affecting the suitability of technical devices during operation is corrosion damage to the metal. Therefore, the influence of various combinations of the mineralization degree and concentration of petroleum products on the corrosion rate of metals most often used in the design of cooling systems for diesel engines and other transport objects was studied. Thus, for carrying out static and dynamic laboratory tests, model working solutions with different salinity (demineralization model) and different concentrations of dissolved petroleum products (model of standard solutions with organic impurities) were selected. Dynamic and static studies of corrosion damage were carried out by the gravimetric method and the method of polarization resistance using standard samples and solutions. Findings. Based on the results of experimental studies of the authors and analytical data processing, generalizing model dependences of the corrosion rate on the mineralization degree of the working solution of the fractional composition of petroleum products were obtained. A study was carried out and the influence of the water demineralization degree on the corrosion rate of materials of diesel cooling systems was established. Originality. Based on a wide range of author's experimental data, the presence of generalizing dependences of the corrosion rate on temperature, the mineralization degree of the working solution and the fraction of the petroleum products composition has been shown and proven. The obtained dependences form the basis of the developed mathematical model of corrosion, which is a set of relationships linking the characteristics of the corrosion process with various factors influencing its development. Practical value. The obtained experimental and analytical data can be widely used for non-destructive testing procedures, detailed prediction of the state of structural elements and the selection of effective inhibitors to reduce the corrosive aggressiveness of the environment and protect structures.