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.

Energy saving at operation of outdoor swimming pools

Abstract: Purpose. Energy saving is a major problem in modern power engineering and various energy-consuming devices. They include outdoor swimming pools. In order to maintain them in working condition, especially in winter period, it takes significant amount of thermal energy. Task of heat loss substantial decrease in open swimming pools is considered in the article (on DNURT example). Methodology . The method of determining the mass and heat loss on the basis of criteria equations of heat and mass transfer theory is used. Findings . Calculations of the actual DNURT pool heat loss for different seasons, as for natural convection both for air forced motion above the free water surface are performed. It is shown that for the adiabatic evaporation conditions of water from the pool in winter during blow-off with wind the heat loss can be up to 2 kW/m2 on surface. To reduce these losses it is offered to cover water surface in a pool with a special material with low thermal conductivity on the basis of porous polyethylene during the time when the pool is not used for other purposes. It is shown that the implementation of these standards will reduce the actual heat loss, at least 5-6 times. Originality . The solution of important environmental and energy problem thanks to reducing heat losses by the pool in different times of a year and correspondingly lower emissions of power generating enterprises. Practical value. It is shown that the coating surface of the pool with poorly heat-conducting and easy to install coating will let, at a minimum, to reduce the actual heat loss on 5-6 times and reduce the emissions of power plants generating energy for pool heating.

About track circuit calculation method dependent on ferromagnet properties in conditions of traction current noise influence

Abstract: Purpose . The work is intended to investigate the electromagnetic processes in impedance bond in order to improve noise immunity of track circuits (TC) for safe railway operation. Methodology . To achieve this purpose the methods of scientific analysis, mathematical modelling, experimental study, a large-scale simulation were used. Findings . The work examined the interference affecting the normal performance of track circuits. To a large extent, part of track circuit damages account for failures in track circuit equipment. Track circuit equipment is connected directly to the track line susceptible to traction current interference, which causes changes in its electrical characteristics and electromagnetic properties. Normal operability, performance of the main operating modes of the track circuit is determined by previous calculation of its performance and compilation of regulatory tables. The classical method for determination of track circuit parameters was analysed. The classical calculation method assumes representation of individual sections of the electrical track circuit using the quadripole network with known coefficients, usually in the A-form. Determining the coefficients of linear element circuit creates no metrological or mathematical difficulties. However, in circuits containing nonlinear ferromagnets (FM), obtaining the coefficients on the entire induction change range in the cores is quite a difficult task because the classical methods of idling (I) and short circuit (SC) are not acceptable. This leads to complicated methods for determining both the module and the arguments of quadripole network coefficients. Instead of the classical method, the work proposed the method for calculating the track circuit dependent on nonlinear properties of ferromagnets. Originality . The article examines a new approach to the calculation of TC taking into account the losses in ferromagnets (FM), without determination of equivalent circuit quadripole network coefficients. When building the FM reversal model in parallel magnetic fields, the most accurate methods are the approximation ones that take into account not only the changes in values and over time, but also their derivatives. The development of computer hardware and software makes real the mathematical methods for calculating TC with significant change in ferromagnetic inductance, including the saturation areas. Herewith, it is important to search for approximating analytical expression that describes the dynamic limit hysteresis loop (HL). Practical value . The changes in the electrical parameters of the same TC were analysed using the classical and the new calculation methods, the difference made less than 10%. The work introduced some measures to increase operational noise immunity of TC.

Reception of the biographical method in historical and anthropogical studies

Abstract: Мета. Актуалізувати питання про використання біографічного методу і встановлення його взаємозв'язку з іншими науковими методами та методологічними принципами в історико-антропологічних дослідженнях. Теоретичний базис. Розгляд біографічного методу в історико-антропологічних студіях здійснений у річищі загального теоретичного «ренесансу» класичної гуманітаристики, що значною мірою викликаний невизначеністю і багатозначністю теоретичних дискурсів і дискурсивних практик постмодернізму, висуває перед дослідником низку нових завдань, серед яких – «виявлення неявного», тобто не простого описування результатів культурної діяльності людини в безпосередній даності, а розкривання часом неусвідомлених механізмів цієї діяльності, глибинних «пружин» культури, що забезпечують її рух. Наукова новизна. Автори даної розвідки не торкаються соціологічної проблематики біографічних досліджень, які широко репрезентовані в працях сучасних західних дослідників. Предмет нашого повідомлення – біографічний метод, що є генетично висхідним від Ш.-О. Сент-Бева, який вважав, що головним завданням біографа є здійснення аналізу особистості видатної людини. Очевидність того факту, що дослідження в царині гуманітаристики загалом і в цивільній історії зокрема мають враховувати не тільки зміни соціокультурних аспектів буття, але й відповідну трансформацію методологічних підходів до аналізу епіфеноменів «текучої сучасності», привела нас до розуміння необхідності історіософського дослідження питання про рецепцію біографічного методу в історико-антропологічних працях з наступною історичною, філософською, культурологічною репрезентацією біографічного методу. Висновки. Історіософські трансформації останніх десятиліть з їх радикальною зміною концепцій, методів і прийомів повертають дослідника до вдосконалення біографічної методології, яка сьогодні репрезентує антропоцентризм, що наповнює науку гуманістичним змістом. Використання даної методології потребує від науковця дотримання основних методологічних принципів і оволодіння іншими науковими методами, насамперед діалектикою.

Optimization of bearing structure of ballast leveling machine SPZ-5/UA

Abstract: Purpose. The results of the optimization investigation and the rational projects of the bearing structure of ballast leveling machine SPZ-5/UA are brought in this paper. The necessity of realization of structural optimization of the investigated machine is reasonable. Methodology . The statement of the optimization problem is executed: the beam cross-section square is taken as the objective function; the allowable stresses criterion is taken as the constraint in this problem statement. Findings. The simplified FE-model of structure of machine is worked out. The optimization problem of double-T cross-section is considered as a test case. For this problem we can obtain the analytical and numeral solutions. Originality. The rational designs for the bearing structure of the investigated machine are brought with the increased consumption of material with preservation of durability characteristics. Practical value. The optimization investigation is executed for bearing structure of the ballast leveling machine SPZ-5/UA by the use of the numerical structural optimization procedure. The obtained rational structural projects are compared to the structural projects with standard double-T cross-sections. It is shown that the use of structural projects with standard cross-sections makes it impossible to obtain the better structure as compared to the rational project. As a result the rational structural project of the ballast leveling machine is obtained, which have the sufficient safety factor. The cross-section of the main longitudinal beam of the bearing structure of leveling machine is decreased on 73%.

Теоретические основы гасителей колебаний трением качения

Abstract: Purpose. There are some unresolved issues in vibration damping – the lack of engineering calculations for the vibration dampers by rolling friction; the absence of evidence of their application appropriateness. Considering this fact, the authors suggest to prove that the dampers based on rolling friction, are similar in rate of oscillation damping by hydraulic shock absorbers. At the same time, they are easier for the hydraulic design, and easily amenable to manual adjustment, both in automatic and manual mode. Methodology. Fixed techniques of practice in order to determine amplitudes of the oscillations of a shock absorber led to a predetermined result and will apply this theory in the calculation of other vibration dampers. Findings . Analysis of the formulas and graphs leads to the following conclusions and recommendations: 1) the nature of the oscillation damping at vibration dampers by rolling friction is close to their decay in the viscous resistance; 2) when conducting the necessary experiments the shock absorber rolling can be recommended as alternatives to hydraulic ones. The research results of this task will help implement the new trend in reduction of dynamic loads in vehicles. Originality. With the help of theoretical curves to determine the coefficients of rolling friction the dependences for determining the amplitudes of the oscillations in the vertical movement of cargo were obtained. At the same time, the previously proposed analytical dependence for determining the coefficient of rolling friction contains only conventional mechanical constants of the contacting bodies and there geometrical dimensions. Practical value. Due to the existing well-known disadvantages of hydraulic shock absorbers it would be logical to apply shock absorbers that are technologically convenient in manufacturing and easy to adjust the damping rate. The proposed theory can be used in the design of shock absorbers rolling as an alternative to the hydraulic shock absorbers of machines.