Dnipropetrovsk National University of Railway Transport

Humans longing to fly higher and quicker have prompted the improvement of hypersonic vehicles. Typically, hypersonic streams are described by high temperature fields and a thin layer of shock close to the object wall or the body surface. To ease the reduction of thermal loads, a blunt nose is forced in a hypersonic vehicle which is more imperative. In any case, increase in the wave drag is one of the quick outcomes of a constrained bluntness. Consequently, investigation in the hypersonic field is constantly fixated on the wave drag decrease. The flow features around the blunt body get changed because of the attachment of spike in front of the vehicle. This chapter aims to give a detailed review of a hypersonic vehicle that involves an aerospike design in front of the blunt body, which tends to reduce the drag at the forebody. Views of various researchers are investigated, and efforts are taken to summarize the reported results on how the drag has been reduced using aerospike technique.

This research uses the finite element method to determine the strength of the bearing structure of a flat car during shunting impacts with. The authors determined the fields of the maximum equivalent stresses in the bearing structure of a flat car. The strength was also researched with the strain-gage method. The test results showed that the maximum difference between the stresses obtained theoretically and experimentally was 17.0%. The strength model of a flat car was verified with an F-test. The calculation demonstrated that the hypothesis of adequacy was not rejected. The research demonstrated that damage to the bearing structure of a flat car and the containers can be decreased by applying an improved interaction scheme. This will reduce the maintenance costs of flat cars and containers, and enhance the efficiency of railway transport.

The training of mining locomotive drivers using simulators will increase the efficiency and intensity of training. Due to this, a decrease in financial and time expenditures for training a driver, an increase in the safety and productivity of his labour will be achieved. The number of errors in the work and damage to equipment, which are sometimes caused by the driver's inexperience, will be reduced. The mining train driver's simulator is manufactured as an autonomous training tool with the trainee immersion in a virtual environment that is as close as possible to a real working environment and is a training complex consisting of hardware and software. The software simulates the operation of all locomotive systems, mining sidings infrastructure and an interactive 3D panorama of the environment. In the driver's cabin of a mining locomotive , a real working environment is reproduced, control, alarm and indication elements of the locomotive, as well as other equipment of a real cabin necessary for performing all technological operations. Training complexes will never replace real experience in the workplace, but they can quickly increase the qualifications of trainees, help them develop the skills of acting in non-standard and emergency situations, which is extremely difficult in real work conditions.

In the paper, structure and properties of novel diamond composite with enhanced properties were presented and discussed. The samples were prepared using the method of cold pressing followed by the originally developed two-stage vacuum hot pressing under electric current activation. It was demonstrated that addition of different amounts of chromium diboride to the WC–6wt.%Co composite had significant effect on its microstructure, phase composition and, hence, mechanical characteristics. It was found that percentage 4wt.% of CrB2 provided the most advantageous characteristics. In the second stage of researches, this composition was used as a matrix for the diamond reinforcement. The obtained results of analysis suggested that enhancement of the composite could be attributed to the dispersed strengthening mechanism and structure modification. In particular, important role played reduction of the average grain size of the carbide phase from 5.6 to 3.4 μm, disappearance of pores at the Co binding phase, formation of inhibitor phase clusters at the interphase boundaries, and the specific pattern of phases present in the composite. Chromium diboride contributed also to the formation of dense and strong interface between diamond grits and refractory matrix. Advantageous distribution of residual stresses around the diamond grits appeared in the sintered samples with CrB2, providing additional fixation of the diamond reinforcement in the matrix. It was also demonstrated that further increase of CrB2 content above 4 wt.% in the WC–6wt.%Co composite material lead to a deterioration in its mechanical properties, which could be attributed to further, disadvantageous changes in the structure, especially in grain size and phase composition.

In many countries around the world, a cubic parabola is used as transition curves in a simplified form. Today, the properties of many mathematical curves are well studied, which can be used as transition curves. The object of research is the process of restructuring transition curves when organizing high-speed trains operation. The use of modern means of mathematical modelling allows to add a number of dynamic characteristics for evaluation parameters of motion in the curved sections of the tracks. Thus, with an increase in speed for transition curves, both the values of unbalanced acceleration and its change in time, and also the velocity attenuation of oscillations of rolling stock when moving from a transition curve to a circular curve or to a direct section. On the basis of the conducted research, it has been found that when increasing the speed of the vehicle movement in the range from 120 to 200 km/h, the length of the stabilization section increases at the output of the curvature by an average of 20 m for every 40 km/h. The analysis showed that with correctly set parameters of transition curves, which correspond to the maximum speed of movement and radius of a circular curve, the strength and reliability of the bearing elements in the structure of the permanent way and the travel comfort are fully ensured.

The operation of locomotives diesel engines involves aging and physical wear of parts, components and assemblies, which leads to a decrease in the probability of failure-free operation and an increase in the number of failures. To increase the probability of failure-free operation and reduce the number of failures of locomotives diesel engines, a certain maintenance system is applied. To manage of diesel engines maintenance processes in a locomotive depot, it is proposed to use the risks of failures. The article presents mathematical models of the risks of failures depending on the operating parameters of diesel engines. Based on the developed models, it is possible to manage the maintenance processes. Comparison of theoretical and experimental results confirms the adequacy of the developed mathematical models and confirms the effectiveness of the proposed approach to determining the risks of failure of diesel engines for managing maintenance processes in a locomotive depot. As a result, a maintenance process for 5D49 diesel engines in the locomotive depot was developed. By managing the maintenance processes of 5D49 diesel engines in a locomotive depot, it was determined that the optimal mileage is 45,000 km. The resource of 5D49 diesel engines in a locomotive depot in the management of maintenance processes increased by 2.4...5.5% compared to the existing maintenance system.

The problem of improving the state of deformation of landmarks is an important aspect when performing civil services, because they have a historical interest and bring symbolisms which relate to an event of particular interest for the community. The engineering–geological surveys, technical evaluation and operational suitability of landmarks of national significance are performed to improve the state of deformation. The conducted analytical assessment of landslide hazard slope stability in the RocScience Slide computational complex shows that in the presence of landslide prevention works, and the stability coefficient is increased by a factor of 1.21–1.37. The regularities of deformation and strength parameters of the soil–cement obtained during the jet-grouting application indicated an increase in strength gain of amplifier elements by an average of 1.6–4.0 times. This proves the effectiveness of the jet-grouting application for improving the state of deformation of landmarks of national significance.

The strength of the coupling device under the action of operating loads with regard to the non-central interaction of two cars is defined. When longitudinal force is transmitted through the coupler, the points of its possible rotation can be either the upper ribs of the shank end surface or the upper ribs of the damping device body support surface. The tail part of the coupler is under conditions of eccentric compression (or tension) by the force, which is non-parallel to the longitudinal axis. Through any cross-section of the shank, transverse and longitudinal forces are transmitted, applied at a point far from the center of gravity of the section. Using the principle of addition of forces action, a dependence for the definition of the maximum normal stresses in the extreme fibers of the analyzed section of the shank of the coupler, the most distant from the main axis of inertia, has been obtained. The damage to the area of the coupler shank jumper and the bending of the shank in the horizontal and vertical planes, which occur during operation, are justified. Calculation methods make it possible to study the influence of eccentricities of longitudinal force application relative to the coupler axis and the difference of coupler axis levels in the analyzed sections on the magnitude of the compressive operating loads. Application of the obtained results will not only help to ensure the strength of the coupling devices, but will also ensure the freight cars' durability under conditions of increasing train weight and increasing train speed.

The paper considers the practical experience of creating educational visual materials on the Ukrainian language as a foreign language using innovative technologies, namely, the specifics of the role and place of colour and colour symbols as a code sign during the assimilation of new educational information. This study employed the following theoretical methods—analysis, systematisation and generalisation of modern research; empirical methods—experimental work; statistical methods—qualitative and quantitative processing of the results of empirical research; systematisation and correlation of the results of empirical research in accordance with the values of the case paradigm of the Ukrainian language. It was established that colour can affect not only a person’s emotions and behaviour, but also cognitive processes, thinking and memory. Upon recollecting information, a person reproduces events and focuses on everything associated with them. Within the framework of this study, the authors have identified the role of the influence of colour on the activation and mobilisation of students’ attention and memory, found ways to learn grammatical categories of the Ukrainian language using a generalising colour table. The authors proved that studying grammatical categories of the Ukrainian language using the colour coding method improves awareness and reproduction of educational information. Context and implications Rationale for this study The process of Eurointegration in Ukraine has an impact on all spheres of life, in particular on the educational system, where significant changes related to the optimisation of technologies, forms and means of teaching, improving the ways of motivating the assimilation of the necessary information are taking place. The quality of international students teaching and its effectiveness need to be improved. The solution to the problem of the effectiveness of the educational materials lies in the harmonious combination of structured content and cognitively oriented design. This paper considers the practical experience of creating educational materials on the Ukrainian language as a foreign language using innovative technologies such as the specifics of the role and place of colour and colour symbols as a code sign in the assimilation of new educational information. Why the new findings matter In the study, it was found that colour can affect cognitive processes, thinking and memory of a person, and the role of the colour influence on the activation and mobilisation of students’ attention and memory was revealed. The results of the research prove that the study of grammatical categories of the Ukrainian language using the colour coding method improves the comprehension and reproduction of teaching information. Implications for educational researchers and policymakers The grammatical table created by the authors contains the most difficult grammatical material for assimilation; it takes into account the basic psychological regularities of visual perception of information, colour influence on the human subconscious and is based on the principle of material accessibility, which manifests itself in the presence of symbols and words that are understandable for the speakers of different languages. Using the developed table, the conjugation of nouns, as well as adjectives and endings of pronouns and ordinal numbers can be studied. Educators should take into account that professional selection of colours significantly increases cognitive and motivational characteristics and decreases the level of negative psychoemotional states.

The relatively high maintenance costs of the ballast track are related to the short lifecycle of the ballast layer. The current vertical ballast tamping technology (e.g., Plasser & Theurer, Matisa, etc.) causes high ballast destruction and is neither applicable for unconventional sleepers’ designs nor slab tracks. The side tamping method presents an alternative, ballast saving, and sleeper form independent ballast tamping technology. This paper compares the ballast layer compaction and its resistance to permanent settlements accumulation after the vertical and the side tamping methodologies. Scaled models of ballast layer and tamping units and scaled simulation with discrete element method (DEM) were applied for the comparison. In the laboratory tests, the ballast compaction along the sleeper was estimated using the measurements of elastic wave propagation. The settlements resistance for both tamping methods was estimated under the vibration loading. The tests’ results show 5–7% higher compactness of the ballast layer under the sleeper ends for the side tamping method. The settlement intensity of the ballast layer after the vertical tamping is higher than for the side tamping method. In discrete element modeling, the performed laboratory tests were simulated. The compactness of the ballast bed, as well as the residual stresses, were determined in MATLAB. The side tamping technology provided five times higher residual stresses in the ballast layer below the sleeper than in the case of vertical tamping, which can be explained by the more stable and dense layer resulting from the side tamping ensures higher interlocking between the grains. The simulation of the wave propagation shows an influence of the residual stresses on the wave propagation velocities. The simulated wave propagation velocity was more than two times higher for the side tamping than for the vertical one.

There is a class of tasks that requires considering the dynamics not only for rolling stock but also for the response of the railway track. One of the directions of railway transport development, which encourages the transition to fundamentally new dynamic models of the railway track, is undoubtedly an increase in traffic speed. To solve such problems, the authors applied a model of the stressed-strained state of a railway track based on the dynamic problem of elasticity theory. The feature of this model is the calculation of dynamic stresses and deformations induced by the spread of elastic waves through the objects of the railway track. Based on the mathematical modeling of stress propagation in the under-rail basis, authors have shown the influence of various objects of a railway track on the formation of the outline of the front of the elastic wave and determined the main time intervals. Furthermore, the authors propose the following analytical method, which, in addition to the soil's physical and mechanical properties, considers the properties of the ballast as a layer that transmits pressure to the roadbed and takes an active part in the formation of the interaction space.

Purpose: The purpose of this paper is to elaborate new calculation schemes for evaluating the strength parameters of railway rolling stock parts with non-local properties of surface layers in the presence of elliptical stress concentrators. Design/methodology/approach: Using the proposed approaches of developed mathematical modelling and open software for calculating FEniCS, it were established the most dangerous angles of stress concentrator orientation and the required thickness of the hardened zones of parts, which ensures their minimum softening during operation. Findings: It is shown that for an elliptical stress concentrator with any orientation angle, there is a certain key size of surface hardening thickness, the exceeding the value of which does not have influence on the operational strength of the parts, but rise the price of technological operations. Research limitations/implications: In this paper proposes a method for computation the impact of the orientation of the surface elliptical stress concentrators on the contact strength of parts under conditions of dominate friction power loads. Practical implications: The obtained results were used to set the modes of plasma hardening, which increase the contact strength of railway parts with elliptical stress concentrators. Originality/value: Using the approaches of contact mechanics, mathematical and computer modelling, methods of controlling the contact strength of the parts with the surface elliptical stress concentrators were proposed for the first time.

The aim of the article is considered the conceptual reconstruction of the relationship between postmodern feminism and the notional field of contemporary neoliberalism. The analytical methods used were based on the assertion that the complexity of textual interventions requires interdisciplinary approaches. The findings and results of the research carried out accentuate that COVID-19 has contributed greatly to the contradictions of the current global landscape in the contexts of neoliberalism and feminism. Feminism asserts as a discourse that the conceptual apparatus of neoliberalism has not served its goals; in fact, postfeminism has not yet chosen its route in the neoliberal context. The assumption that women cannot win their “vindication battle” in the world where "the game is fixed" continues to be taken as an axiom, even though the coronavirus pandemic causes some observers to proclaim the return of influential governments and social contracts. The latter accentuates the role of female representation in neoliberal social, cultural, and political discourses at the global level.

This paper is an outcome of an international collaborative research initiative. Researchers from 24 institutions across 12 countries were invited to discuss the state-of-the-art in railway train air brake modelling with an emphasis on freight rains. Discussed models are classified as empirical, fluid dynamics and fluid-empirical dynamics models. Empirical models are widely used, and advanced versions have been used for train dynamics simulations. Fluid dynamics models are better models to study brake system behaviour but are more complex and slower in computation. Fluid-empirical dynamics models combine fluid dynamics brake pipe models and empirical brake valve models. They are a balance of model fidelity and computational speeds. Depending on research objectives, detailed models of brake rigging, friction blocks and wheel-rail adhesion are also available. To spark new ideas and more research in this field, the challenges and research gaps in air brake modelling are discussed.

The replacement of ferrous metals with lighter non-ferrous ones, in particular with aluminum and its alloys, is of great importance for reducing the specific material consumption of products. Modification of aluminum alloy D16 with combined electro spark coating VK8 + Cu is considered. Based on the method of finite element analysis of the Nastran software complex, an optimal coating continuity was determined at the level of 55-65%, which provides efficient workability of the coating via reducing the residual stresses in the base and tangent stresses in the plane of adhesive contact, optimization of the coating continuity, distribution of contact loads, and formation of optimal surface geometry. The results of modeling the stress-strain state of the coating-base at a coating continuity of 60% and a normal load of 600 N indicate a 30 MPa increase in equivalent stresses in a unit element of the coating and a decrease of this parameter by 100 MPa in the base as compared with an unmodified D16 surface, indicating the localization of normal stresses mainly in the combined coating. It was experimentally established that at a combined coating continuity of 60%, reduction of D16 wear by 2 times and decrease in the average power of acoustic emission by 1.33 times are provided, which testifies to the efficient structural adaptability of the coating-base under friction. The mechanisms of increasing the wear resistance of the VK8 + Cu coating according to the rheological-kinetic model, which reflects the correlation between processes of fracture and deformation under friction, are considered. It is determined that the high wear resistance of the combined coating is due to the combination of rheological properties of hard alloy VK8 with a fracture toughness of 13.2 MPa·m 1/2 and plastic copper material with a fracture toughness of 100 MPa·m 1/2 , which contributes to the efficient relaxation of stresses under friction.

The paper is devoted to analysis of modern directions of innovation-investment formation of intelligent computer networks that control the fast-moving technological processes of electricity supply. It is based on the conclusion that the problem of increasing the productivity of information exchange between information resources and consumers is dominant. A method for increasing the efficiency of information exchange is proposed as a search for the rational location of a new node and the organization of such a set of its connections among the whole set of nodes of the computer network, which provides a minimum average topological distance. Mathematical models of effective topological organization of connections in computer network of power consumption control at the level of traction substations, electric power distances and the railway in general are proposed.

Modern high-tech composite materials are widely used in various sectors of the economy, in particular, in railway transport. Among the areas of application of such innovative materials, the manufacturing of contact strips for pantographs of electric rolling stock should be mentioned. Innovation is primarily understood as the self-lubricating property of the working surface of the linings. The linings made of such materials differ from the traditional graphite (coal) ones by the increased content of metal additives, in particular copper, which limits the possibility of their use on electric rolling stock in the countries of the European Union. Regulatory restrictions on the content of copper (35% and 40%) are associated with possible damage to the contact wire, in the case of using overlays with a content of copper (metals) greater than these restrictions. On the railways of Ukraine (countries of the former USSR), there are also restrictions on the use of linings of different types according to the degree of wear of the contact wire, no more than 40 microns is allowed per 10 thousand passes of the locomotive pantograph along the contact wire. These standards are verified during operational and bench tests. The aim of the article is to present the types of tests and compare the obtained values with similar indicators in the case of using a traditional contact strip for pantographs of electric rolling stock. The results obtained confirm the possibility of using innovative linings on iron networks, since the wear of the contact wire during testing is much lower than that of the normative and knife than for traditional types of linings. In addition, during a set of tests, the fact of improving the quality of the working surface of the contact wire was established, which positively affects the extension of the service life of the contact wire.

It is established that at various technological processes at repair of a rolling stock of railways electric drives of the universal non-standard equipment can constantly work in essentially underloaded mode that leads to deterioration of their power indicators. The aim of the work is to quantify the reduction of active power losses when replacing constantly underloaded asynchronous motors of unregulated electric drives of universal non-standard technological equipment used in the repair of railway rolling stock with less powerful ones. In this work, the subject of research are the motors of electric drives of this equipment. The analysis of technological processes at repair of a rolling stock, technical characteristics of the specified equipment is carried out and the conclusion is accepted that first of all it is expedient to investigate efficiency of replacement on the equipment of the established engine on less powerful at carrying out at the specialized enterprises of such technological processes warehouse (wheel pairs, traction motors, auxiliary electric machines, frames of rolling stock carts, etc.). The load of the electric motors of transport trolleys of equipment is proposed to be defined as the ratio of the weight of a large unit of electric locomotive, diesel locomotive, electric train and other types of rolling stock to the carrying capacity of universal non-standard equipment of transport trolley. The term "universal" equipment is introduced in the work, which means equipment for performing a certain technological process in the repair of various large units of different types of rolling stock, as well as "specialized enterprise" specializing in the repair of rolling stock, large units which weigh significantly less, than the load-lifting capacity of the transport cart of the equipment. Therefore, the motors of electric drives of universal equipment at these enterprises are constantly operating underloaded. Also actions for quantitative assessment and reduction of active power losses in the electric drive motor are offered.