Browsing by Author "Gera, Bogdan V."
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Item Estimation of Private Locomotives Usage Efficiency for Freight Transportation in Ukraine(Dnipro National University of Railway Transport named after Academician V. Lazaryan; Les Ulis: EDP Sciences-Web of conferences, 2019) Kozachenko, Dmytro M.; Gera, Bogdan V.; Sannytskyy, Nazar М.; Hermaniuk, Yuliia M.; Shargun, TetyanaENG: Abstract. Ukraine has undertaken the implementation of European Union Directives, which provide nondiscriminatory admission to the railway infrastructure of independent carriers. A significant number of factors considerably affect working conditions of the carriers which are independent of Ukrzaliznytsia. One of the goals while performing transportation by independent carriers is the organization of private locomotives operation and their service by engine crews. The purpose of the article is to assess technical and economic indices of private locomotives use for goods transportation. The schemes of infrastructure objects arrangement for locomotives operation and engine crews work are presented. Performed calculations show the potential possibility of independent railway carriers to fulfil transportation to seaports with the use of its private locomotive infrastructure exclusively. The estimation of economically expedient volumes of cargo transportation by private locomotives in comparison with existing pricing of Ukrzaliznytsia is carried out. The nonlinear dependence of transportation volume depending on the distance is determined, at which the total cost of cargo transportation by Ukrzaliznytsia locomotives is equal to the cost of cargo transportation by private locomotives. The results of the study allow concerned companies to evaluate the investment efficiency into the development of locomotive fleet for rail transportation.Item Improvement of the Method for Standardizing the Duration of Rail Cars Shunting(НГУ, Дніпро, 2021) Kozachenko, Dmytro M.; Gera, Bogdan V.; Manafov, E. K.; Gorbova, Aleksandra V.; Korobiova, Ruslana G.ENG: Purpose. To improve the method for calculating the time standard for shunting cars from track to track in order to take into account the local operating conditions of railway stations and railway sidings. Methodology. During the research, the methods of theory of railway operation were used. The problem of calculating the time standard for shunting operation was solved as the problem of searching the optimal division of train set into the car groups to achieve minimal time consumption for shunting operation. Findings. In the course of the study, the methods for calculating the time standards for initial and fi nal operations, as well as movements performed when shunting cars from track to track were improved. It was proved that the minimum time spent on shunting cars from track to track was achieved when the train set was divided into the minimum possible number of parts and the cars were shunted in the longest possible groups and one remaining group. It was also established that with suffi cient accuracy for engineering problems the duration of shunting train set from track to track can be represented by the piecewise linear function of the car number in it. Originality. The work originality consists in improving the method for calculating the time standard for shunting cars from track to track, that, unlike the existing one, takes into account the length limitations of the car groups being shunted from track to track, as well as the actual composition of operations performed in the process of shunting. Practical value. The use of the developed method allows setting time standards for shunting cars from track to track, taking into account the local operating conditions of railway stations and sidings of industrial enterprises. The method also makes it possible to simplify solving problems of searching the optimal order of performing more complex shunting operations, such as sorting cars into several tracks, collecting cars on one track, train formation, and others.Item Improvement of the Method of Time Rationing for Assembling Car Groups on One Track(Dnipro University of Technology, Dnipro, Ukraine, 2024) Kozachenko, Dmytro M.; Gera, Bogdan V.; Taran, Ihor; Korobiova, Ruslana H.; Malashkin, Vyacheslav V.; Hermaniuk, Yuliia M.ENG: Purpose. To improve the method for standardizing the duration of the shunting operation of assembling cars on one track. This can be achieved as a result of solving the following research problems: development of a method for searching the optimal order of assembling cars on one track; distribution parameters estimation of the random value of the duration of shunting operation of assembling cars on one track based on calculation experiments. Methodology. During the research, the methods of theory of railway operation, dynamic programming and mathematical statistics were used. Findings. Research on the assembling process of car group to one track established the distribution parameters of the random variable of time spent for shunting. In the course of the research, the problem of choosing the optimal order of shunting operations during car assembling was formalized and solved as a problem of dynamic programming. The time spent for shunting work was chosen as the optimality criterion. The paper considers the possibility of approximating the data of calculation experiments by analytical dependencies. It was found out that the use of linear polynomials with interaction allows obtaining dependencies describing time standards with a relative accuracy of ±5 %. Originality. The method is improved for developing the time standards for shunting work, which, unlike the existing one, is based on the performance of a series of calculation experiments, each of which solves the optimization problem of finding such an order of assembling cars that ensures minimum time consumption for shunting. Practical value. The methods developed in the work and the dependencies obtained allow improving the quality of decisions made when developing technology and designing railway stations and sidings of industrial enterprises.Item Longitudinal Vibrations of Viscoelastic Longitudinally Nonuniform Rod under Power Load Distributed Along its Length(Lviv Polytechnic National University, Lviv, 2016) Gera, Bogdan V.; Sitarz, Marek; Bolzhelarskyi, Yaroslav V.EN: In this article, the dynamic behavior of a moving elongated object is simulated using the relations for a viscoelastic rod, which moves at a constant speed under the action of traction force and distributed along its length external forces of resistance. We investigate the change of displacements and internal forces after the sudden application in the rod section of the local force directed longitudinally. The correlations of the initial boundary value problem that describes the dynamic behavior of the rod are written down, and its solution is obtained in the form of a series expansion in terms of eigenfunctions. For a viscoelastic rod consisting of three connected uniform rods, the analysis of wave processes induced by the application to the rod of a sudden concentrated force that resists the motion is carried out. This affects the motion of the rod as a whole, and induces the wave processes, the propagation and reflection of waves on the inner surfaces of joints. The comparison is performed for the behavior of an elastic, piecewise nonuniform rod and a viscoelastic rod with different mechanical characteristics, where the waves during their propagation are damped and smoothed.Item A Model of Transit Freight Distribution on a Railway Network(The Silesian University of Technology, Katowice, Poland, 2019) Kozachenko, Dmytro M.; Skalozub, Vladyslav V.; Gera, Bogdan V.; Hermaniuk, Yuliia M.; Korobiova, Ruslana G.; Gorbova, Aleksandra V.ENG: Summary. The peculiarity of the transit freight transportation by rail in international traffic is the fact that while performing transportation, the railway administrations are in competition among themselves. At the same time, the routes of cargo traffic volumes sig- nificantly depend on the conditions of transportation by railways of individual states. The mathematical model for the distribution of transit freight traffic volumes on the railway network, based on the methods of graph theory and game theory, was proposed in this ar- ticle. The developed model enables the evaluation of the possibilities of attracting transit freight traffic volumes by indi by changing the tariff value and transportation conditions.Item Obtaining and Investigation of the Conditions of Heat Transfer Through Inhomogeneous Inclusion with Heat Sources(Національний університет «Львівська політехніка», Львів, 2015) Gera, Bogdan V.; Dmytruk, Veronika A.EN: The conditions of nonideal heat transfer are obtained for a heat conduction problem of contacting layers through a thin heterogeneous sublayer (inclusion) with acting heat sources (heat sinks). These conditions include both thermal resistances of components of the inclusion and specific powers of heat sources in them. On this basis, the heat conduction problem with nonideal conditions of heat transfer without consideration of inner inclusion is written down. Their use ensures observable features of temperature and heat flux, i.e. the function of temperature and the function of heat flux have a drop when passing through the contact interface. The magnitude of thermal resistance is suggested to be determined by means of more usual for measuring values, e.g. a thermal conductivity coefficient and a thickness of the inclusion. Surface specific heat sources can be set if the values of heat dissipation on the contact boundary are known. From the obtained and generalized heat transfer conditions, the known conditions of nonideal thermal contact can be obtained as particular cases.Item An Optimization Method of the Multi-Group Train Formation at Flat Yards(Taylor & Francis Ltd., UK, 2021) Kozachenko, Dmytro M.; Bobrovsky, Volodymyr I.; Gera, Bogdan V.; Skovron, Ihor Ya.; Gorbova, Aleksandra V.ENG: Formation of multi-group trains is aimed at arranging their cars in a given order and is one of the mass operations performed at railway. In this regard, the reduction of the duration of shunting operations for the formation of multi-group trains is an urgent task for railway transport. In this paper, for a discrete deterministic-controlled system that simulates the operation of the flat yard, a mathematical statement of the problem of choosing the optimal order of multi-group train formation is obtained. The set of possible states of the system under study and the transitions between them are presented in the form of directed graph, which made it possible to reduce the problem of choosing the order of train formation to the problem of searching the shortest paths on the graph. An algorithm of searching the optimal order of train formation is proposed.Item A Study of the Effects of Climatic Temperature Changes on the Corrugated Structure of a Culvert of a Transportation Facility(PC "Technology Center", Ukrainian State University of Railway Transport, Kharkov, 2019) Gera, Bogdan V.; Kovalchuk, Vitalii V.EN: The results of experimental studies of temperature distribution on the surface of a metal corrugated sheet are presented. It is assumed that temperature depends on two spatial variables. As a possible criterion for the selection of the desired function of temperature distribution structure minimization of the functional defined on the set of admissible functions in the form of an integral over the body region from the expression that determines the entropy production is taken. In the study of the temperature field, the differential equation of thermal conductivity is used, and the stress-strain state is the equation of the theory of thermal elasticity. The finite difference method was used to solve the differential thermal conductivity equation and the finite element method was used to solve the thermoelasticity equations. It is established that the temperature is distributed unevenly by metal corrugated sheet. There is a temperature difference between the lower and upper surfaces of the corrugated metal sheet. The temperature difference between the lower and upper surfaces of the sheet is +7.1 ° C at maximum additional ambient temperatures and –5.5 ° C at minimum negative temperatures environment. It is established that the magnitude of stresses that occurs in metal corrugated sheets from environmental temperature differences, up to 25% of the allowable stresses. Therefore, when designing metal corrugated structures, it is necessary to calculate the effect of temperature climatic influences. The obtained data of thermal stress of corrugated metal structures are important for design organizations. Since, given the effect of the temperature field on the stressn state of the structure as a whole at the design stage, it is possible to select materials in order to reduce the temperature stresses that have a direct impact on the development corrosion damage to metal pipe.