Browsing by Author "Hololobova, Oksana O."
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Application of Fourier Transform and Wavelet Decomposition for Decoding the Continuous Automatic Locomotive Signaling Code(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Hololobova, Oksana O.; Havryliuk, Volodymyr I.EN: Purpose. The existing system of automatic locomotive signaling (ALS) was developed at the end of the last century. This system uses the principle of a numerical code which is implemented on the basis of relay engineering, and therefore, it is exposed to various types of interferences. Over the years, the system has been upgraded several times, but the causes of faults and failures in its operation are still the subject of research. It is known that the frequency and the phase modulation of signal has a higher interference immunity as compared to the amplitude modulation. Therefore, the purpose of the article is to study the possibility of using the frequency methods such as Fourier series expansion and wavelet decomposition to extract the informational component of the received code from ALS signals under the action of various types of interferences. Methodology. One can extract the information unavailable in time representation of the signal using the signal studies in the frequency domain. The wavelet decomposition has been used for this purpose. This makes it possible to represent the local characteristics of the signal and to provide time-frequency decomposition in two spaces at the same time. Due to the high accuracy of the signal representation it is possible to analyze the time localization of spectral components and eliminate interference components even in the case of coincidence of interference frequency with the signal carrier frequency. Findings. To compare informativity of the methods of Fourier expansion and wavelet decomposition it was studied the reference and noisy signal of green fire code using the software package MATLAB. Detailed analysis of the obtained spectral characteristics showed that the wavelet decomposition provides a more correct decoding of the signal. Originality. Replacing the electromagnetic relays in the ALS system by microprocessor hardware involves the use of some mathematical tool for decoding, in order to obtain more information about the code. More often than not, as a mathematical tool, the classical Fourier decomposition is used. But because of a number of drawbacks in this method, it was suggested to use the wavelet decomposition, which has a number of advantages and accounts the disadvantages of the Fourier transform. Practical value. The presented method of code signal research can be the basis for developing dynamic model of the ALS receiver and decoder using digital processing module, which will enable to increase the reliability and accuracy of extraction of the code information component.Item Features of Design of Tied-Arch Bridges with Flexible Inclined Suspension Hangers(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпро, 2017) Samosvat, V. O.; Rongling, Zhang; Hololobova, Oksana O.; Buriak, Serhii Yu.EN: Purpose. Investigation and analysis of the hanger arrangement and the structural stability of a Network arch bridge – a tied-arch bridge with inclined hangers that cross each other at least twice. It is also necessary to make a comparative analysis with other types of hanger arrangements. Methodology. The authors in their research investigateda large number of parameters to determine their influence in the force distribution in the arch. Eventually they determined optimal values for all parameters. These optimal values allowed developing a design guide that leads to optimal arch design. When solving this problem, the authors used three-dimensional finite element models and the objective was to determine the most suitable solution for a road bridge, with a span of 100 meters, consisting of two inclined steel arches, located on a road with two traffic lanes, subjected to medium traffic. The virtual prototype of the model is performed by finite element simulator Midas Civil. Findings. In this study, for the bridge deck, a concrete tie appears to be the best solution considering the structural behavior of network arches, but economic advantages caused by easier erection may lead to steel or a composite bridge deck as better alternatives. Design requirements and local conditions of each particular bridge project will decide the most economic deck design. Originality. To ensure passenger comfort and the stability and continuity of the track, deformations of bridges are constricted. A network arch is a stiff structure with small deflections and therefore suitable to comply with such demands even for high speed railway traffic. A network arch bridge with a concrete tie usually saves more than half the steel required for tied arches with vertical hangers and concrete ties. Practical value. Following the study design advice given in this article leads to savings of about 60 % of structural steel compared with conventional tied arch bridges with vertical hangers.Item Mathematical Modelling of the Communication Channel between the Rail Circuit and the Inputs Devices of Automatic Locomotive Signalization(Dnipro National University of Railway Transport named after Academician V. Lazaryan, 2019) Hololobova, Oksana O.; Buriak, Serhii Yu.; Havryliuk, Volodymyr I.; Skovron, Ihor Ya.; Nazarov, Oleksii A.ENG: Abstract. In modern practice of operating under traffic safety conditions, the traffic light signal must be transmitted to the locomotive that moves to it, and duplicate in the driver's cab. However, this communication channel is not protected from external interference. In order to prevent the occurrence of code failure, it is necessary to create conditions under which the automatic locomotive signalling system will distinguish between signals with useful information, from signals with false information. The best way to solve this problem at the first stage is to model the devices. Using the simulation tools of graphical environment of simulation modelling Simulink from Matlab software environment, the software model of the communication channel between the railroad and the input devices of automatic locomotive signalling system was constructed. The created mathematical model with the actual parameters allows us to obtain diagnostic signs of a proper condition, on the basis of which the research is aimed at the identification, recognition and definition of various types of malfunctions, failure, damages and defects in the work of the constituent elements of the system and the signal transmission channel of the automatic locomotive signalling system.Item Modeling of Electromechanical Systems(Дніпровський національний університет залізничного транспорту ім. акад. В. Лазаряна, Дніпро, 2018) Buriak, Serhii Yu.; Havriliuk, Volodymyr I.; Hololobova, Oksana O.EN: Real time systems mode and transmit data on the instantaneous state of the control objects can timely detect any faults and thus provide additional time for their correction by railway employees. Turnouts are one of the most important and responsible components, and therefore require the development and implementation of such diagnostics system. Achieving the goal of monitoring and control of railway automation objects in real time is possible only with the use of an automated process of the objects state diagnosing. For this we need to know the diagnostic features of a control object, which determine its state at any given time. The most rational way of remote diagnostics is the shape and current spectrum analysis that flows in the power circuits of railway automatics. Turnouts include electric motors, which are powered by electric circuits, and the shape of the current curve depends on both the condition of the electric motor, and the conditions of the turnout maintenance. For the research and analysis of AC electric point motor it was developed its mathematical model which satisfies the conditions of adequacy. The calculation of parameters and interdependencies between the main factors affecting the operation of the asynchronous machine was conducted. The results of the model operation in the form of time dependences of the waveform curves of current on the load on engine shaft were obtained. On the basis of the constructed model we can study the AC motor in various mode of operation, record and analyze current curve, as a response to various changes of the load on engine shaft.Item Study of Transmission Lines Effect on the System Operationon of Continuous Automatic Cab Signalling(Дніпропетровський національний університет залізничного транспорту імені академіка В. Лазаряна, Дніпропетровськ, 2014) Hololobova, Oksana O.; Havryliuk, Volodymyr I.; Kovryhin, Mykhailo O.; Buriak, Serhii Yu.EN: Purpose. To conduct an effect research of the electromagnetic field of high-voltage transmission lines (HVTL)(750 kV, 50 Hz) on the track circuits and continuous automatic cab signalling (CACS) with a signal current of 50 Hz in the areas of convergence and intersection with the transmission lines and to propose possible methods to improve noise immunity of CACS. Methodology. The measurements were performed both by means of car-laboratory and directly on rail lines. During the study the electric field strength in the range of industrial frequency directly under the transmission lines and at the distance from it to the railway lines was measured, as well as the time dependence of CACS codes with signal current frequency of 50 Hz directly under the transmission lines and at a distance from it in the absence of the train and its passing. Findings. The root causes analysis of CACS faults and failures was carried out. The effect of the electromagnetic field of high-voltage transmission lines (750 kV, 50 Hz) on the track circuit and CACS with signal current of 50 Hz in the areas of convergence and intersection with the transmission line was investigated. Possible methods to improve noise immunity of CACS were considered. Originality. The effect research of transmission lines (750 kV) on the operation of the automatic cab signalling on spans Prishib-Burchatsk and Privolnoye-Yelizarovo, Pridneprovsk railway in places of oblique railroads crossing and transmission lines (750 kV, 50 Hz) was conducted. Electric field strength in the range of industrial frequency directly under the transmission lines and at a distance from it to the railway line, as well as the time dependences of ALSN codes with signal current frequency of 50 Hz directly under the transmission lines and at a distance from it in the absence of the train and as its passing were measured. It was found that CACS codes in track circuits under transmission lines are strongly distorted, as strength measurements of electric field are shown, it can be explained by the electromagnetic field effect of transmission lines on track circuits. Practical value. Possible methods of CACS safety enhancement by improving the reliability of signaling from a track on the locomotive were considered.