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.

Detecting of Signal Distortions in Cab Signalling System Using ANFIS and WPESE

Abstract: The problem considered in the work is concerned to detecting of signal distortions occurred in the railway ALSN cab signaling system. The ALSN system is designed to transmit track status information into the train cab and uses rails as a continuous communication channel between track and train. The amplitude and duration of the pulses in the ALSN code combinations are changed over time due to deterioration of the track transmitters and other devices in the signal transmission channel, as well as due to electromagnetic influence of the traction current, rails magnetization, and other sources of electromagnetic interference. Due to distortions of ALSN signals, their decoding becomes unstable, which leads to intermittent failures in the form of temporary incorrect indication at the cab traffic light or to complete failure of the ALSN system. Diagnostic of the ALSN system and the revealing of signals with distortions is carried out by analyzing the signal current, recorded using the railway car-laboratory. However, the use for this purpose of the classifiers with sharp boundaries for input diagnostic parameters and strict rules for signal selection does not allow us to reveal incipient defects that arise in the ALSN system. The work investigates the effectiveness of using adaptive neuro-fuzzy inference system (ANFIS) and wavelet packet energy Shannon entropy (WPESE) for timely detecting of signal distortions in the ALSN system. The obtained results confirmed the efficiency of ALSN signal processing using ANFIS and WPESE for detecting of railway sections with unstable or faulty ALSN system.

Properties of Modified Concrete for Special Purpose Structures

Abstract: Purpose. The paper is aimed at developing the scientific fundamentals of new-generation monolithic concrete technology for special purpose structures by controlling the processes of structure formation of a modified cement system under natural hardening conditions. Methodology. The kinetics of interaction between the cement system and aggregates was evaluated by microcalorimetry. The measurements were carried out continuously for 24 hours after preparation of the mixture. The differential and integral characteristics of the heat release of the solidifying system were recorded. Investigation of the rheological properties of concrete mixtures was carried out on the mixtures with 10...15 cm consistency. The microhardness of contact layers was investigated on concrete cubes with dimensions from 20×20×20 to 50×50×50 mm. When determining the structural characteristics, x-ray phase and differential-thermal analyzes of the concrete cement matrix were used. Infrared spectroscopy was used to determine the effect of physicochemical modification on the cement system. Tensile creep was studied over a wide load range from 0.2 R t to 0.8 R t . Findings. It is determined that the reason for changing the concrete properties of natural hardening is the change in its hygrometric and thermal state, as well as the harmonic fluctuations of these environmental factors. The hygrometry of concrete depends on the thermal moisture conditions of the environment, the type and composition of concrete, the massiveness of concrete elements. An analysis of these factors and experimental data made it possible to establish the exponential dependence of the change in the hygrometric state of monolithic natural hardening concrete. The change in the moisture state of concrete makes it possible to predict its volumetric deformations. Originality . For the first time, the features of the structure formation of a modified cement system are established, consisting in the fact that magnesium chloride hydrate crystals grow rapidly in the space between hydrated clinker minerals, and the resulting mechanical cohesion defines the development of initial strength and rigidity. Since the free growth of crystals is hampered by a lack of space, the crystals mutually intergrow, forming a dense structure, contributing to the growth of strength. The developed organo-mineral modifying complex provides disperse reinforcement of the cement matrix of concrete. Practical value . The obtained dependences of structural concrete stresses make it possible to analyze their effect on the structure of modified concrete: to determine the probability of formation around the filler particles of the plastic flow zone, the material microcrack formation zone, the crack initiation period, the microcrack onset conditions, and the change of elasticity modulus of the material caused by microcracks in its structure. Disperous modification of cement matrix allows to obtain durable concrete of special purpose with design operational properties. The developed binder disperse modification technology, the established features of the structure formation mechanism for the modified cement system, as well as the use of the principle of congruence of a complex of technological influences to the physico-chemical processes of hydration of clinker minerals allowed developing the scientific fundamentals for the special purpose concrete technology. This helps to expand the use of modified concrete in various types of construction.

Solution of task of the mobile loading in the dynamic statement

Abstract: Мета. Особливістю статичної роботи тунельних конструкцій є те, що їх напружено-деформований стан формується у взаємодії з навколишнім масивом. Але, у свою чергу, динамічна складова напружено- деформованого стану такого роду конструкцій також велика, оскільки тунельні конструкції сприймають, окрім постійної дії навколишнього масиву, спектр динамічних навантажень. Аналізуючи кожен вид динамі- чної дії, слід також давати йому оцінку з позиції відображення в нормативних документах, оскільки урахування більшості динамічних дій тільки декларується в них без розробки будь-яких методик. Методика. Для дослідження впливу рухомого навантаження в динамічній постановці модель змінено для того, щоб коректно прикласти навантаження між колонами у вигляді імпульсу. Як і проведеному дослідженні рухомого навантаження в статичній постановці, в якій було з’ясовано, що його вплив на станційну конструкцію залежить від глибини закладення, при вирішенні цієї ж задачі в динамічній постановці досліджені дві моделі із глибиною закладення 5 і 10 м. Результати. Із проведеного аналізу можна свідчити, що комплексний аналіз станційної конструкції із проведенням статичних та динамічних розрахунків дозволяє отримати більш повну інформацію про напружено-деформований стан, яка дозволяє оцінити стан елементів в різних ситуаціях, деякі із яких вірогідно призводять до аварійних ситуацій і повинні бути прогнозовані. Наукова новизна. Проаналізовано вплив рухомого навантаження в статичній та динамічній постановках. Практична значимість. Розрахунки станцій метрополітену мілкого закладення доповнюються важливим розрахунком в динамічній постановці, а результати такого комплексного аналізу можуть вважатися більш повними.

Emergency Burning of Solid Rocket Propellant: Damage Risk Assessment to People in the Workplace

Abstract: Purpose. This work includes the development of a computer model to calculate the risk of thermal damage to people in the shop in case of emergency burning of solid rocket propellant. Methodology. To calculate the temperature field in the shop in order to determine the zones of thermal damage to workers in the building, the equation expressing the law of energy conservation was used. Based on this modeling equation, the temperature field in the shop is calculated in the presence of a source of heat emission – burning solid rocket propellant. To calculate the velocity field of air flow in the shop, taking into account the location of obstacles in the path of heat wave propagation, we used the model of vortex-free air motion – the equation of the velocity potential. A two-step finite difference scheme of conditional approximation is used to numerically solve the equation for the velocity potential. A difference splitting scheme was used to numerically solve the energy equation. At the first stage of construction of the difference splitting scheme of the two-dimensional energy equation into the system of one-dimensional equations is performed. Each one-dimensional equation allows you to calculate the temperature change in one coordinate direction. The point-to-point computation scheme is used to determine the temperature. When conducting a computational experiment, the air exchange in the building is taken into account. The risk assessment of thermal damage to personnel in the building is performed for different probabilities of the place of emergency combustion of solid rocket propellant. Findings. Using numerical model prediction of the potential risk areas of thermal damage to staff in the shop for a variety of emergency situations was performed. Originality. A computer model for rapid assessment of the potential risk of damage to people in the shop in case of emergency burning of solid rocket propellant was constructed. Practical value. The authors developed a code that allows you to quickly simulate the temperature fields formation in the shop in case of emergency burning of solid rocket propellant and to identify potential areas of thermal damages to workers based on this information. The developed computer program can be used to assess the risk of thermal damage in the chemical industry in case of emergency.

The ways of the freight train trucks design improvement

Abstract: В статье проведен анализ факторов, влияющих на износ пары «колесо – рельс», и сделан вывод о целесообразности создания в узле «боковина – букса» кинематической пары третьего рода.