Science and Transport Progress

20-27

Authors: A. Bialon, D. Adamski, Ju. Furman

Purpose. Axle counters are more and more often applied in train detection systems. The wheel sensor is a main part of each axle counter system. In parallel, more and more complex railway vehicles, especially traction ones, are a potential source of interferences influencing the operation of these train detection systems. It is the reason to verify the electromagnetic compatibility (EMC) between the signalling equipment, particularly train detection systems and new vehicles in the process of obtaining the permission for their exploitation. The measurement of interfering magnetic fields generated by vehicles is one of tests to be carried out. Methodology. For the simplification and unification purpose of the applied interference test methods the EN 50238 standard and TS 50238-3 technical specification were developed. The specification defines unified testing procedures. However, it is necessary to verify if it may replace different testing methods used in particular European states. It is the goal of the European research project financed from the TEN-T network resources. Findings and originality. This project is part of the larger project of facilitation and speeding up the ERTMS system deployment. One of nine measurement campaigns planned in the frame of this project was conducted in Poland by Railway Research Institute.

41-48

Authors: M. Kycko

Purpose. The publication presents the importance and influence of railway traffic control system documentation on its safety. Furthermore, it presents certain selected issues of formal and semi-formal descriptions. Methodology. Development of correct and complete descriptions of the informal, semi-formal and formal becomes important in terms of safety requirements. Background documentation and forms of command-control and signaling system description are the base documents of safety proof. It seems necessary to implement the analysis of the design, manufacture process and operation of safety-related equipment into the work of the Polish railways. Firstly it is applied to traffic control devices. Findings. This publication also shows the importance of risk analysis, which is essential when deciding on the implementation of signaling systems to operate, which are required both in the regulations and making rational decisions about the implementation of the systems. Originality. The presented a problem changes the approach to certain data and makes us aware of their validity. Practical value. The presented problems can help understand certain legal requirements.

49-59

Authors: Yu. V. Zelenko, L. O. Neduzha, A. O. Shvets

Purpose.The success of the traffic on the railways of Ukraine depends on the number and the operational fleet of electric locomotives. Today, the locomotive depot exploit physically and morally outdated locomotives that have low reliability. Modernization of electric locomotives is not economically justified. The aim of this study is to improve the safety of the traction rolling stock by the frequency analysis of dynamical systems, which allows conducting the calculation of the natural (of resonant) frequencies of the design and related forms of vibrations.Methodology.The study was conducted by methods of analytical mechanics and mathematical modeling of operating loads of freight locomotive when driving at different speeds on the straight and curved track sections. The theoretical value of the work is the technique of choice of constructive schemes and rational parameters of perspective electric locomotive taking into account the electric inertia ratios and stiffness coefficients of Lagrange second-order equations.Findings. The problems of theoretical research and the development of a mathematical model of the spatial electric vibrations are solved. The theoretical studies of the effect of inertia ratios and stiffness coefficients on the dynamic values and the parameter values of electric locomotive undercarriages are presented.Originality.The set of developed regulations and obtained results is a practical solution to selecting rational parameters of bogies of the freight mainline locomotive for railways of Ukraine. A concept of choice of constructive scheme and rational parameters of perspective locomotive is formulated. It is developed the method of calculation of spatial electric locomotive oscillations to determine its dynamic performance. The software complex for processing the data of experimental studies of dynamic parameters of electric locomotive and comparing the results of the theoretical calculations with the data of full-scale tests is implemented.Practicalvalue.The theoretical study allows objectively assessing the impact of the partial frequency of electric locomotive elements on both the rational parameters of its underframe, and the performance and physiological condition of the locomotive crew. Thus, the practical value of the whole complex of theoretical research was to develop an algorithm and program, choosing rational parameters and design scheme of electric locomotive running gear. Using a software package for the study of spatial fluctuations of electric locomotive made it possible to evaluate the dynamic performance of the electric locomotive underframe with sufficient accuracy for practical problems.

97-107

Authors: O. M. Pshinko, V. H. Kuznetsov, D. K. Yatsenko, V. O. Gabrinets

Purpose. The paper analyses the possibility and terms of increasing the efficiency of heating and ventilation systems of public buildings at the present stage of development and the specific climatic conditions of Ukraine. The main purpose is to develop specific measures for public buildings, which will lead to a significant reduction in energy costs for heating and air conditioning system. The example is similar system of DNURT compact campus, which is heated with its own autonomous boiler that uses natural gas. Methodology. The statistical heat loss analysis for the last 5 years allows defining the types and calculating the heat loss values for specific conditions. These losses are compared with those in the world practice and based on the comparison and analysis of the current system there are offered the ways to reduce the heat loss values through the use of various technical and organizational methods.The paper also proposes involvement for this purpose of secondary and alternative energy sources. The secondary energy resources include the heat that is emitted by people and that coming out with the air during ventilation of buildings. The renewable sources include solar and geothermal energy. To enhance the heat transfer medium temperature capacity it is proposed to use the heat pumps. Findings. The maximum possible use of the proposed measures and implementation of rational schematic and engineering solutions for heat and hot water supply systems cam reduce the energy loss for heating and hot water by 30-35%. Originality. The paper for the first time proposed the use of new integrated approaches to maintain the desired heat balance in the winter period, as well as the new schematic solutions for heating and ventilation systems, both in winter and in summer, based on the use of heat pumps and secondary energy resources. Practical value. The introduction of the proposed schematic solutions and approaches demand relatively small capital investments and do not require significant reconstruction of already installed systems.

120-129

Authors: L. V. Trykoz, I. V. Bahiiants

Purpose. The article deals with the insulation resistance of the track circuit as one of the parameters that affect the operating performance of the railway transport. To reduce the influence of the insulation resistance on the operation modes of the track circuits and the performance indicators of railway transport it is assumed to study the influence of crushed stone treatment on the value of dielectric permeability of the ballast bed. Methodology. The influence of material type for the surface treatment of crushed stone on the value of the dielectric permeability was assessed on the basis of the physical nature determination of the relative dielectric permeability. Determination of the relative dielectric permeability of granular media can only be indirect, as a consequence of incomplete adjoining of crushed stone grains and uncertainty of the pore volume. Thus, the calculations were performed by comparing the measured capacity for a medium with the known with measured medium capacity, for which it is necessary to define. That is, the more the measured capacity is changed, the more changes the dielectric permeability of the medium. Findings. Sleepers and ballast significantly change their electrical conductivity depending on the presence of moisture, ambient temperature changes, the presence of pollutants and other factors. The article analyzes the existing models to describe the dielectric properties of such systems. It has been established that coating the crushed stone ballast with organic substances influences the value of its relative dielectric permeability. The greatest effect of reducing this value is observed for the coatings based on rosin mixture and silicone. Originality. Authors proposed original method of dielectric properties increase of the permanent way by grains’ coating with nonwettable substances, on the surface of which is not formed a water film. Practical value. The article shows the possibility of minimizing the negative influence of reducing the isolation with maximum its elimination. It is proposed the solution of actual problem by eliminating the influence of insulation resistance on the modes of track circuits operation, which will eliminate the part of causes of the failure of signaling devices and reduce the number of cases of «false business».

138-147

Authors: V. V. Netrebko

Purpose. This article analyzes the formation conditions, transformation and systematization of carbide phases formed in the system Fe – C – Cr.Methodology. Conversion of the elements’ content from mass % into atomic % and vice versa was carried out using standard methods. In order to identify the structural components and etching of carbides the Marble etchant was applied. Cast iron 300Х28Н2 in cast state without heat treatment and after isothermal holding at 1050 °С during 4.5 hours with further normalization was studied. Findings. Isothermal state diagrams of the Fe–C–Cr system don’t take into account the existence of Fe7C3 carbide alloyed with chromium. But there is evidence of the existence of chromic carbides containing 24…37.6 % of chromium, which exceeds its maximum solubility in cementite, but is not enough to form Cr7C3.Analysis of chromium and carbon content in carbide phases which are formed in high-chromium cast irons allowed to substantiate the formation of Fe7С3 carbide, stabilized with chromium. Assessment of the carbide phase by chemical composition in mass percent doesn’t allow determining the main carbide-forming element with sufficient accuracy. It is shown that with the increase of chromium concentration in carbides, mass content of carbon increases. Areas of existence of carbides of different types depending on carbon and chromium content in them were determined. Maximum content of chromium in the carbide (Fe, Cr)7C3 is 44.0 %. Allocation of alloyed cementite occurs on the present carbides Ме7C3 or grain boundaries, and with the increase of cooling rate – in the grain volume. This process is thermodynamically inevitable due to the decrease of carbon solubility in ferrite or austenite at temperatures when chromium diffusion is impeded, and only carbon diffusion is possible. At high chromium concentrations carbide Fe7C3 is formed, which transforms into Cr7C3 carbide as chromium diffusion takes place. Originality. The model of laminated structure of carbides, formed out of the liquid phase in the system Fe–C–Cr was built. The identification of the carbide phase based on the elements’ concentration in atomic percent was suggested. The model of the change of carbon content in carbides of different types depending on chromium concentration was built. Practical value. The suggested system of carbide classification and their structural model allows optimizing the cast irons’ composition and heat treatment modes for different exploitation conditions.

161-170

Authors: L. M. Bondarenko, M. O. Babyak, S. O. Yakovlev, S. O. Istin, G. Yu. Moskalev

Purpose. About one of the causes of slip rolling is known from the second half of the 19th century, it was believed that the slip resistance appears at the place of contact due to different speeds on the arc of contact. Only in the mid-20th century it was proved that this resistance is negligible in rolling resistance. However (for some unknown reason) it is ignored the fact that in practice in rolling bearings may rotate both the inner ring with a stationary outer one, and vice versa almost in equal relations. It is not taken into account the fact that the ball or roller in the rolling bearings runs the different distance along the roller path of the outer and inner bearing cages in one revolution. This fact is not taken into account in determining the calculated values for the friction coefficient of a rolling bearing reduced to the shaft. Therefore, the aim of this work is to determine the influence of path length on the track riding the outer and inner race of the bearing on the determination of the calculated value of the coefficient of friction of rolling bearings is given to the shaft. Methodology. The solution technique is based on the theory of plane motion of a rigid body, the theory of Hertzian contact deformation and the analytical dependencies for determination of coefficient of rolling friction. Findings. The obtained dependences on determination of rolling resistance of the balls or rollers along the bearing tracks of inner and outer bearing cages as well as path difference metering of the rolling on them allows to analytically obtain the rolling resistance and slipping for any size of bearings and different devices of bearing units. It is also possible at the design stage of rolling nodes to handle not only the design but also the content of the node. Originality. Using the analytical dependences for determination of the rolling resistance of bodies at point and line contacts, and also account for the difference in the path of the rolling ball or roller on the outer and inner cages of the bearing one can more accurately find the rolling resistance in the bearings. Practical value. The obtained dependences allow designing the bearing units with minimal energy consumption.

181-190

Authors: A. D. Malyi, T. V. Ulchenko, A. S. Shcherbak, Yu. Ya. Popudniak, T. V. Starosolskaya

Purpose. Study of geometric transformations. We will consider the so-called point transformations of space. Methodology. The most important are one-to-one transformations. They allow exploring and studying the properties of the transformed object using the properties of the original object (line, surface and figure) and the properties of the transformation. Cremona transformations occupy a special place in the set of one-to-one nonlinear transformations. Construction of one-parameter (stratifiable) transformations is carried out as one-parameter set of plane transformations, both linear and non-linear ones. The plane, in which the specific transformation is prescribed, moves in space by a certain law forming a one-parameter set of planes. The set of such plane transformations makes up the space transformation. Findings. The designed graphics algorithms and the established transformation equations allow building the visual images of transformed surfaces and conducting their research by analytical geometry methods. Originality. By completing elementary algebraic transformations of this equation, we obtain the cissoids equation. If the plane is continuously moved parallel to itself, it results in occurrence of surface, whose carcass will be the set of cissoids and the set of front-projecting lines. Practical value. The considered set of stratifiable algebraic transformations gives an effective means for exploring new curves and surfaces obtained by transforming the known algebraic lines and surfaces. These graphic algorithms allow graphically depicting the transformed lines and surfaces. The considered procedure of drawing up analytical formulas of specific transformations allows us to study the transformed surfaces and lines using the methods of analytic geometry. The above transformations can be of arbitrary high order, which is especially important during the design of complex technical surfaces such as aircraft components, parts of water and gas turbines, supports of the structures subject to strong flow of liquid, etc. Space modelling issues, including the building of graphic plane models of space, are relevant both in theoretical terms and in terms of application of the non-linear surfaces investigated on their basis for constructing the technical forms of parts and aggregates of construction machine movable elements, the middle surfaces of shells, the surfaces of turbulent blade, etc.