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.

Procedure for determining process characteristics of friction stir welding

Abstract: Purpose . The study is aimed at improving the procedure for determining the optimum radius of the shoulder of a special tool for friction stir welding (FSW) of aluminum alloys and its change depending on the variations of base metal thickness. Methodology. The friction stir welding process was carried out on specially designed equipment. The material for the studies were 1.85 mm thick plates made of aluminum alloy AMg3 with a chemical content of alloying elements within the range of the brand composition. The temperature in the welding zone and the pressure from the tool on the edges of the welded joint were determined using a specially designed research stand. The pressing force of the tool to the base metal during welding was measured with a dynamometer type DC-0.1 with the indicator head. Findings . During the research, the degree of metal heating and the quality of the welded joint formation were determined at various ratios of the rotation frequency of the working tool and the normal pressure to the joining edges. The research allowed determining the influence of FSW process parameters on the temperature of metal heating in the action zone of the working tool shoulder. Originality . The experimental studies allowed to determine the effect of the working tool rotation speed and the magnitude of its pressure on the welded metal during welding on the temperature in the weld zone. Increasing the tool rotation frequency allows to reduce pressure of the working tool during welding, which results in more efficient and high-quality welding process. It has been established that it is possible to obtain better welded joints at a temperature of about 0.7 Tm and to determine the optimal temperature range in the welding zone. Practical value . The study resulted in determination of the conditions for achieving the permanent softening effect during friction stir welding and the optimum temperatures in the welding zone for the tested alloy. The main technological parameters of the working tool are calculated and their influence on the generation of thermal energy in the welding zone is determined. The thermal analysis of the welding process resulted in development of the procedure for determining the technological parameters of the working tool and its rotation frequency depending on the weld metal thickness.

Diagnosis of relay-contact devices of railway automatics

Abstract: The analysis of existing methods of construction of diagnostic tests of discrete devices is carried out, algorithms and the program of construction of checking and diagnostic tests for the relay-contact equipment of railway automatics are developed.

Methodology approach for calculation of tourist time travel on the narrow gauge

Abstract: The author conducted a study of different types of tourist traffic with the use of modern rolling stock will run on narrow gauge railways. The methodical approach for calculating the duration of tourist trips on narrow gauge, which is based on considering time traffic railway train on the route, the number of trips and the stay of tourists on them, stay in hotels and restaurants that will advance to schedule different types of tourist trips on narrow-gauge railway and minimize the costs of their organization. Rationally applied measures proposed by the author directions managing tourist flows will increase revenues to the budget from domestic tourism.

Modeling of biological wastewater treatment on the basis of quick-computing numerical model

Abstract: Purpose. The scientific paper involves the development of quick computing numerical model for prediction of output parameters of aeration tank. The numerical model may be used in predicting the effectiveness of aeration tank under different regimes of work. Methodology. To simulate the process of biological wastewater treatment in aeration tank numerical models were developed. The flow field in the aeration tank is simulated on the basis of potential flow model. 2-D transport equations are used to simulate substrate and sludge dispersion in the aeration tank. To simulate the process of biological treatment simplified model. For the numerical integration of transport equations implicit difference scheme was used. The difference scheme is built for splitting transport equations. Splitting of transport equation into two equations is carried out at differential level. The first equation of splitting takes into account the sludge or substrate movement along trajectories. The second splitting equation takes into account the diffusive process of substrate or sludge. To solve the splitting equations implicit difference scheme was used. For the numerical integration of potential flow equation the implicit scheme of conditional approximation was used. On the basis of constructed numerical model computer experiment was performed to investigate the process of biological treatment in aeration tank. Findings. Quick computing numerical model to simulate the process of biological treatment in the aeration tank was developed. The model can be used to obtain aeration tank parameters under different regimes of work. The developed model takes into account the geometrical form of the aeration tank. Originality. The numerical model which takes into account the geometrical form of aeration tank and fluid dynamics process was developed; the model takes into account substrate and sludge transport in aeration tank and process of biological treatment. Practical value. Efficient numerical model, so called «diagnostic models» was proposed for quick calculation of biological treatment process in aeration tank.

Transient Stochastic Processes in Power Circuits of Electric Transport Systems

Abstract: The analytical method for the purpose of analyzing the transient processes occurring in the power traction circuits of DC electric transport systems allowing to take into account existing stochastic character of electric traction voltages and currents has been proposed. The method is based on using a modified form of Duhamel's integral adapted to the theory of random processes, in which the weight function is determined by the solution of the Wiener-Hopf correlation integral equation. Based on relationships of the proposed method the numerical calculations of transient stochastic characteristics (the function of mathematical expectation, the function of correlation, root-mean square deviation and dispersion) of the locomotive current in freight train operation of the Prydniprovsk railway were carried out.