Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan

About: Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan is a education organization based out in Dnipro, Ukraine. It is known for research contribution in the topics: Track (rail transport) & Bogie. The organization has 736 authors who have published 655 publications receiving 1468 citations. The organization is also known as: Institute of Railway Transport Engineers.

Audio Frequency Track Circuits Monitoring Based on Wavelet Transform and Artificial Neural Network Classifier

Abstract: The problem of revealing and identifying of signal disturbances in audio frequency track circuits is considered in the article. Track circuits are a key component of automatic train control system and used to detect whether the rail section is free or occupied. Amplitude-modulated signals used in track circuits have low noise immunity, therefore the power wide-band-frequency interference generated by an electrified railway can cause failure operation of track circuits. To ensure the safety of the track circuits, they are subjected to periodic maintenance with registration of the signal current to the computer and measurements of its parameters. The detection of time intervals during which the interference in the track circuits exceeds certain limit values is performed by simple visual analysis of the recorded signal and is time consuming and expensive. In order to automate the revealing and identification of disturbances in audio frequency track circuits with values exceeding the certain level, a new method for processing of the recorded signal have been proposed. At the first stage, the segments of a signal with interference exceeding a certain permissible level are revealed using the wavelet packet energy Shannon entropy. At the second stage, for the revealed segment with disturbances, a detailed analysis of the signal should be carried out using the digital wavelet packet transform to determine the type and parameters of the disturbances. For automatic identification of the track circuits signal disturbances, an artificial neural network classifier has been used. As a result of investigation the features of the signal disturbances in audio frequency track circuits have been extracted. The processing of the track circuits signals in accordance with the proposed method show high effectiveness in the revealing and identification of the signal disturbances.

Development of Methods for Optimizing Reactive Power Modes Based on Neural Network Technologies

Abstract: The high cost of electric power, as well as the considerable length and branching of electrical networks, necessitate reduce electric power consumption, and losses in electrical networks. One of solutions of this problem is optimizing the reactive power mode. Reducing the reactive power factor at the point of common coupling (PCC) to the economic level established by the power system is not taking into account that in a complex network, power flows with a non-optimal arrangement of compensating devices and improper determination of their power can reach large values, that resulting in an increase in losses in the network. A program has been developed that implements prediction algorithms using neural networks, as well as optimizing the reactive power mode.

Controlling the speed of rolling cuts in conditions of reduction of brake power of car retarders

Abstract: Purpose. The study aims to develop the requirements for organization of the marshalling process in the conditions when the power of retarder positions is less than the nominal one. Methodology. The research is carried out using the train traffic safety theory and mathematical modelling of hump processes. Findings . The current technical standard documents regulating the operational performance of humps do not contain direct instructions on how to proceed in the event of brake power loss by car retarders, thus creating threats to the traffic safety. This problem is quite acute for the Ukrainian railways in connection with a chronic shortage of funds for the repair and renewal of technical equipment, including the humps. At the same time, a significant drop in the volume of work leads to the fact that the hump required processing capacity can be provided in case of partial failure of retarders as well. Herewith the most important task is to ensure the breaking-up safety in conditions of parametric failures of retarders. The analysis of dangerous situations, the occurrence of which is possible at humps, as well as the modelling of cut rolling, allowed establishing the connection between the value of retarder tire pressing force on the car wheels and the breaking-up modes, providing the safety of marshalling process. The paper sets the application areas of such measures as the breaking-up speed reduction, breaking-up termination, the use of additional braking by block hangers. Originality. The originality of the work lies in the fact that it first obtained the complex of dependencies that determine the performance requirements for the power of hump retarders and allow the staff to enter the appropriate limits for breaking-up modes to ensure the marshalling process safety. Practical value. The results of the research can be used to supplement the «Instruction on the maintenance of facilities of mechanized and automated humps» in order to determine the limits of breaking-up modes when detecting the reduction of retarder power below the nominal one.

Theoretical and experimental research of strength properties of spine beam of freight cars

Abstract: Purpose . The purpose of this paper is to analyze the results of theoretical and experimental studies of the strength properties of rolling stock; search for design tools, modeling, selection, justification of the service life extension of freight cars and their elements. Methodology . The article is based on the finite element method (FEM). It makes possible to completely automate the calculation of mechanical systems, although, as a rule, it requires a much larger number of computational operations than the classical methods of mechanics. The modern level of development of computer technology opens wide opportunities for the introduction of FEM into engineering practice. FEM is implemented in many well-known and widely distributed software products that provide strength analysis of models of machines, mechanisms, structures, including the rolling stock of railways. Findings . The article presents an analysis of the theoretical and experimental studies of the strength properties of rolling stock elements on the example of the spine beam of freight cars; calculations were performed using a modern application program package. The presented example of use of the offered approach has shown its operation capacity and efficiency, as well as correctness of the research direction. The offered approach can be used when solving similar optimization tasks in research and developmental practice of transport mechanical engineering. Originality . The authors proposed me-thod of determining the reliability indicators and solving scientific and applied problem of calculating the elements of freight cars, taking into account the operation features and the loading mode impact. This allows determining their durability at the design stage. There were developed and investigated the models of the spine beam of a freight car, on the basis of which the dependences characterizing the stress-strain state of its elements were obtained. Scientifically substantiated results of the evaluation of strength properties of spine beams of freight cars were obtained depending on their design. The aspects related to the current state and development prospects of railway transport, the use of the software complex in the design and calculation of rolling stock in the railway industry are considered. Practical value . The theoretical and experimental studies of the strength properties of rolling stock elements were considered on the example of a spine beam in a freight car. Calculations were performed using a modern software package. The application of these results will contribute to increase the safety of freight cars and improve the technical and economic performance of railway transport.

Некоторые аспекты определения устойчивости порожних вагонов от выжимания их продольными силами в грузовых поездах

Abstract: Purpose. Despite of the implementation various programs to improve the safety of train traffic problem of reducing gatherings rolling stock off the rails is still relevant. The study aims to clarify the existing method of determining the factor of stability from the tire longitudinal forces to ensure the sustainability of cars with increasing speeds of the rolling stock. Methodology. Research was conducted by the method of mathematical modeling of loading freight car when driving at different speeds on straight and curved track sections. Findings. Analysis of the results shows that, for all selected freight cars for the calculation, the value of the safety factor by squeezing is smaller than the formulas of Standards. Corrections made to the formula for determining the safety factor by squeezing longitudinal forces, would achieve: 1) a higher safety factor of lightweight cars, excluding them squeezing longitudinal forces in the entire range of speeds of freight trains; 2) to develop and implement measures to prevent squeezing of cars in the entire range of motion; 3) to determine the degree of stability of the empty car in the head, middle and tail laden trains; 4) to offer optimal scheme of mixed trains formation. Originality. The analysis of existing methods for determining stability coefficient cars in freight trains from squeezing their longitudinal forces is presented in studies. Proposals are developed for the refinement of the design phase, construction and operation. Practical value. This study clarifies the existing method of determining the safety factor of stability from the squeezing longitudinal forces, as well as the influence on the magnitude of the coefficient of speed of movement of the rolling stock. Developed proposals for the refinement of existing methods for determining stability coefficient of longitudinal forces squeezing cars in a train, can reduce the number of retirements cars derailed by taking into account in the calculation and design of important parameters and characteristics that increase their stability in the rail track especially with increasing speeds of freight traffic.