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.

Influence of shock voltage from the electric discharge on the fatigue endurance of carbon steel in water

Abstract: Purpose. The research supposes the explanation of influence of stress impulses from an electrical discharge in water on the level of the limited endurance at a cyclic loading of the thermally work-hardened carbon steel. Methodology . Material for research was steel 45 (0,45 % carbon) with сoncentration of chemical elements within the limits of steel composition. Specimens for tests are made as plates in 1 thick, width 15 and length 120-180 mm. The structural state of steel corresponded to quenching on a martensite from the normal temperatures of annealing and tempering at 300C, duration of 1 h. Microstructure was investigated with the use of electronic microscopy, the density of dislocations was estimated on the methods of X-ray analysis. Hardness was measured on the method of Rockwell (scale of «C»). A cyclic loading was carried out in the conditions of symmetric bend on a tester «Saturn-10» at a temperature +20C. The treatment by shock voltage from the electrical discharge was carried out in water on setting of bath type «Iskra-23», used for cleaning of castings manufactures. Electric impulses were formed at 15-18 kV with energy of 10-12 kJ and amplitude of 1-2 GPа. Findings. As a result of processing pulses of a pressure wave of heat-strengthened steel 45 found the increase of endurance under the cyclic loading corresponds to an increased amount of accumulated dislocations on the fracture surface. The use of Coffin–Manson Equation allowed finding the decrease of deformation per cycle of loading as a result of arising stress from an electrical discharge in water. On the fracture surface (after pulse exposure) was found the increased number of dislocations, located in different crystallographic systems, that is a testament to the rather complicated development of dislocation transformations in the structure of steel, which provide an increase of endurance at a fatigue. The increase of the limited endurance became as a result of impulsive treatment largely related with the number change of mobile dislocations. For the area of low-cyclic fatigue the growth of amplitude of loading is accompanied with the decrease of distinction in the values of the limited endurance (before and after the treatment of shock voltage). Originality. For the field of high-cycle fatigue, the result of shock voltage of carbon steel with the structure of the improvements, the increase of limited endurance is accompanied with a decrease in deformation per cycle. As far as growth of amplitude of stress cycle the effect of increase of endurance from treatment of metal by the shock voltage declines. Practical value. Treatment of metal by the impulses of pressure waves from an electrical discharge in water can be used for the time extending of exploitation details of the rolling stock, which are subjects of the cyclic loading.

3d numerical model for territorial risk assesment after terrorist act

Abstract: Purpose. A goal of the work is development of 3D numerical model for a territorial risk assessment in a case of a terrorist attack with usage of a chemical agent. Methodology. To describe the process of chemical agent dispersion in the atmosphere, emitted in a case of a terrorist attack, the equation of mass transfer of an admixture in atmospheric air is used. The equation takes into account a velocity of the wind flow, atmospheric diffusion, an intensity of chemical agent emission, a buildings presence near a place of a chemically hazardous substance release. For numerical integration of the modeling equation, a finite difference method is used. A feature of the developed numerical model is possibility of a territorial risk assessment in a case of a terrorist attack under different weather conditions and a buildings presence. For calculation of wind flow velocity field in a case of building presence 3D equation for potential of velocity is used. Findings . The specialized numerical model and software package which can be used for a territorial risk assessment, both in a case of terrorist attacks with usage of chemical agents, and in a case of extreme situations at chemically hazardous facilities and transport are developed. The method can be implemented on small and medium-powered computers, which allows it to be widely used for solving this class of problems. The results of a computational experiment are presented that allow estimating possibilities of the proposed method for assessing a territorial risk in a case of a terrorist attack with usage of chemical agent. Originality. An effective method of a territorial risk assessment in a case of a terrorist attack with usage of a chemically hazardous substance is proposed. The method can be used to assess a territorial risk in an urban environment, which allows to obtain adequate data about possible affected areas. The method is based on numerical integration of the fundamental mass transfer equation, which expresses the law of conservation of mass in a liquid medium. Practical value. The proposed method for a territorial risk assessment in a case of a terrorist attack with usage of a chemical agent can be used to calculate the affected areas near administrative buildings, centers and other socially significant facilities.

Influence of electric spark on hardness of carbon steel

Abstract: Purpose. The purpose of work is an estimation of influence of an electric spark treatment on the state of mouldable superficial coverage of carbon steel. Methodology . The steel of fragment of railway wheel rim served as material for research with chemical composition 0.65% С, 0.67% Mn, 0.3% Si, 0.027% P, 0.028% S. Structural researches were conducted with the use of light microscopy and methods of quantitative metallography. The structural state of the probed steel corresponded to the state after hot plastic deformation. The analysis of hardness distribution in the micro volumes of cathode metal was carried out with the use of microhardness tester of type of PMT-3. An electric spark treatment of carbon steel surface was executed with the use of equipment type of EFI-25M . Findings . After electric spark treatment of specimen surface from carbon steel the forming of multi-layered coverage was observed. The analysis of microstructure found out the existence of high-quality distinctions in the internal structure of coverage metal, depending on the probed area. The results obtained in the process are confirmed by the well-known theses, that forming of superficial coverage according to technology of electric spark is determined by the terms of transfer and crystallization of metal. The gradient of structures on the coverage thickness largely depends on development of structural transformation processes similar to the thermal character influence. Originality . As a result of electric spark treatment on the condition of identical metal of anode and cathode, the first formed layer of coverage corresponds to the monophase state according to external signs. In the volume of coverage metal, the appearance of carbide phase particles is accompanied by the decrease of microhardness values. Practical value . Forming of multi-layered superficial coverage during electric spark treatment is accompanied by the origin of structure gradient on a thickness. The effect of the superficial work-hardening from a spark according to a level can be an alternative to majority of thermal and chemical-thermal technologies of treatment of metallic materials.

Sexual representation in the postmodern philsophical discourse

Abstract: The purpose of the article is to discover the peculiarities of the interpretation of sexual representation in the postmodern philosophical discourse; to analyze the way of becoming the category of sexuality an integral part of feminine subjectivity; to compare the ways of interpretation of the category of sexuality in the works of the Western and Ukrainian researchers. Methods and approaches. To investigate the theoretical framework in the postmodern philosophy the cross-disciplinary approach is used. The comparative approach is methodologically important to clarify the problems concerning feminine subjectivity. The very approach provides the researcher with the opportunity to review the cultural peculiarities of the given historical period. Scientific novelty. Following the peculiarities of the gender approach it was discovered that the modern interpretation of the category of feminine subjectivity includes not only racial, class and ethnical differences, but the peculiarities of a sexual character. Unfortunately, the category of sexuality is still the way of women’s oppression. Nevertheless, this category is now an important tool when representing the versatile nature of feminine subjectivity. The problems of sexual marginality are considered to be the way of destroying gender stereotypes. Conclusion. It is proved that the postmodern philosophical discourse has contributed serious transformations when interpreting the feminine nature and changed the attitude to the very category of sexuality. The interpretation of the category of sexuality is a certain touchstone clarifying the attitude towards a human being in general and towards a woman in particular. It is determined that nowadays the problems of sexuality raise some concerns and anxiety posing more questions than giving the answers. One point is absolutely clear: it is impossible to investigate the nature of a modern human being out of the postmodern philosophical discourse. What is more, it is impossible to investigate the postmodern philosophical discourse out of the categories of human sexual representation.

Increasing efficiency of the wastewater treatment plant of khorol factory for baby food

Abstract: Article history: Received 23 April 2019 Accepted 30 May 2019 Print 25 June 2019 The aim of the work is to study the efficiency of the wastewater treatment plant at Khorol factory for baby food and to propose ways to improve quality of wastewater treatment. Some pollutants concentration exceeding the maximum permissible concentration for discharges is observed. In order to eliminate this problem, some solutions are proposed. To increase wastewater treatment effectiveness at the plant, recirculation of wastewaters and replacement of current filling material of the tower biofilters with plastic plate blocks is proposed.