Rail Carriage Research Articles

Analysis of the application of CPMV model to the thermal comfort of passengers in high-speed rail carriages

Due to the popularization of high-speed rail (HSR), there have been increasing concerns of passengers about the thermal comfort of HSR air conditioning. The corrected predicted mean vote (CPMV) model considering the impact of solar radiation on indoor thermal comfort has been previously proposed and validated for accuracy in office buildings. To verify the accuracy of the CPMV model in evaluating the thermal comfort of passengers inside HSR carriages, the field study on HSR in the Yangtze River Delta region of China was conducted in winter and summer. The results indicate thermal sensation vote values obtained from passengers fit well with CPMV values. When the temperature is high in summer and low in winter, the CPMV model ignores people’s ability to adapt and tolerate harsh environments. In addition, the thermal preference temperature of passengers in summer is 0.57°C higher than the neutral temperature, indicating that there is an overcooling situation in summer. The study recommends to lower the set temperature of summer air conditioning in HSR. This study contributes to the promotion of the CPMV model on HSR and provides technical support for the design of air-conditioning systems for HSR carriages from the perspective of thermal comfort of passengers.

Electromagnetic Environment Assessment and Safety Research of Electrified High-Speed Railway Carriages

With the advent of modern, high-speed electrified rail systems, there has been increasing concern about electromagnetic safety in rail carriages. The aim of this study was to assess the electromagnetic safety of passengers on trains by utilizing advanced 3D electromagnetic simulation software. A comprehensive model of the electromagnetic environment experienced by passengers on a CR400AF train, specifically under the influence of catenary radiation, was constructed. We analyzed the magnetic field strength, electric field strength, and current density in the brains of 20 passengers in various positions in the train. The findings revealed that among the 20 passengers analyzed, the maximum and minimum magnetic induction intensity recorded in the brain were 8.41 and 0.01 μT, respectively. The maximum and minimum induced electric field intensities were 1110 and 10 μV/m, respectively. Lastly, the maximum and minimum induced current densities were 1200 and 10 μA/m2, respectively. The results show that when people ride on the CR400AF train, the magnetic induction intensity, induced electric field strength, and induced current density in the brain are below the recommended basic limits of exposure to power frequency electromagnetic fields in the guidelines of the International Committee on Non-Ionizing Radiation Protection. The power frequency magnetic field generated by the catenary can be effectively shielded by the aluminum alloy car body. The final result of this study indicates that the electromagnetic exposure from the contact wire at the level 25 kV does not pose a threat to the health of passengers on the CR400AF train.

Improved Synchronous Sampling and Its Application in High-Speed Railway Bearing Damage Detection

Synchronous analysis is one of the most effective and practical techniques in rotating machinery diagnostics, especially in cases with variable speed operations. A modern analog-to-digital convertor (ADC) usually digitizes an analog signal to an equal time interval data series. Synchronous resampling converts the data series from an equal time interval data series to an equal shaft rotation angle interval data series. This conversion is usually achieved in the digital domain with the aid of shaft speed information, through either direct measurement or identification from a measured vibration signal, which is a time-consuming process. In order to improve the computational efficiency as well as the data processing accuracy, in this paper, a fast synchronous time-point calculation method based on an inverse function interpolation procedure is proposed. By identifying the inverse function of the instantaneous phase with respect to time, the calculation process of synchronous time points is optimized, which results in improved calculation efficiency and accuracy. These advantages are demonstrated by numerical simulations as well as experimental verifications. The numerical simulation results show that the proposed method can improve calculation speed by about five times. The synchronous analysis based on the proposed method was applied to a bearing fault detection in a high-speed rail carriage, which demonstrated the advantages of the proposed algorithm in improving the signal-to-noise ratio (SNR) for bearing damage feature extraction.

Analysis of the movement of an empty railcar on the longitudinal profile of the sorting slide

The article uses analytical formulas derived from the application of the basic law of dynamics for non-ideal connections (the Dalembert principle), the calculation of the kinematic parameters of the rail carriage movement (acceleration, time, braking path) in the braking zone on the site of the first braking position of the sorting slide is performed. All over the world, it is becoming increasingly important to design and build modern sorting stations, as well as to choose the right height for sorting slides. The main function of the sorting slide at railway stations is the disbanding of trains, as well as the formation of new trains. Sorting will depend on how rationally the profile of the descending part of the slide is designed. Calculation of the height of the descending part of the slide and design work is carried out according to the existing method, according to which the movement of the railcar on the slope of the sorting slide, the speed is determined by the expression of the rate of fall of the railcar vertically, taking into account the inertia of the rotating masses. This, in turn, creates several problems. In developed countries, including the US, Germany, Sweden, China, India, and Russia much attention is paid to the development of methods, such as mechanization and automation of sorting ways of stations that affect haul transport and local rail network [1-7].

The effect of ribs on the sound radiation directivity of rectangular plates

An analytical solution utilizing a double finite sine integral transform method is presented in this study for the sound radiation prediction of a ribbed rectangular plate structure under various combinations of clamped and simply supported boundary conditions. An advantage of the modeling method is that the plate–beam structural coupling and the structure–fluid coupling are automatically defined in the integral transformation without the need to manually select the mode shape function. The model is then utilized to investigate the effect of ribs on the radiated sound power and directivity of the plate structure under resonant and non-resonant conditions, respectively. The result shows that the ribbing effect on the omnidirectional radiated sound field of the rectangular plate is consistent with the change of the radiated sound power. However, the radiated sound pressure may increase at certain directions even if the radiated sound power of the rectangular plate is suppressed by the inclusion of ribs. The effect of periodic ribs on the sound radiation of the rectangular plate is also explored. The insight gained from this study can inspire the noise design for structures, such as marine platforms and high-speed rail carriages.

Effect of ventilation mode and airflow rate on the flow field and particle mass concentration distribution of a high-speed rail carriage in the putty polishing workshop

Objectives. The putty polishing procedure usually produces a large number of micron-sized particles, which can lead to serious respiratory diseases as well as skin conditions. The diagonal ventilation system is widely used to decrease the particle concentration in different environments. However, it becomes less effective for a large empty factory workshop, such as the polishing workshop for high-speed rail carriages, in which the diagonal ventilation mode usually results in turbulence in the airflow. In this article we report that the situation can be improved by optimizing the number and locations of the air inlets and outlets in the carriage-polishing workshop. Three modified ventilation modes are proposed, whose efficiencies are evaluated by numerical simulations and compared to the diagonal mode. Results. The results show that the mode with two inlets close to the ceiling and two outlets close to the floor yields the best performance. Besides, the optimum airflow rate under this mode is further determined by both simulations and in-situ measurements. The results reported can serve as a reference for the design of the ventilation systems in the polishing workshops of similar sizes.

The Pressure Peaking Phenomenon for Ignited Under-Expanded Hydrogen Jets in the Storage Enclosure: Experiments and Simulations for Release Rates of up to 11.5 g/s

This work focuses on the experimental and numerical investigation of maximum overpressure and pressure dynamics during ignited hydrogen releases in a storage enclosure, e.g., in marine vessel or rail carriage, with limited vent size area, i.e., the pressure peaking phenomenon (PPP) revealed theoretically at Ulster University in 2010. The CFD model previously validated against small scale experiments in a 1 m3 enclosure is employed here to simulate real-scale tests performed by the University of South-Eastern Norway (USN) in a chamber with a volume of 15 m3. The numerical study compares two approaches on how to model the ignited hydrogen release conditions for under-expanded jets: (1) notional nozzle concept model with inflow boundary condition, and (2) volumetric source model in the governing conservation equations. For the test with storage pressure of 11.78 MPa, both approaches reproduce the experimental pressure dynamics and the pressure peak with a maximum 3% deviation. However, the volumetric source approach reduces significantly the computational time by approximately 3 times (CFL = 0.75). The sensitivity analysis is performed to study the effect of CFL number, the size of the volumetric source and number of iterations per time step. An approach based on the use of a larger size volumetric source and uniform coarser grid with a mesh size of a vent of square size is demonstrated to reduce the duration of simulations by a factor of 7.5 compared to the approach with inflow boundary at the notional nozzle exit. The volumetric source model demonstrates good engineering accuracy in predicting experimental pressure peaks with deviation from −14% to +11% for various release and ventilation scenarios as well as different volumetric source sizes. After validation against experiments, the CFD model is employed to investigate the effect of cryogenic temperature in the storage on the overpressure dynamics in the enclosure. For a storage pressure equal to 11.78 MPa, it is found that a decrease of storage temperature from 277 K to 100 K causes a twice larger pressure peak in the enclosure due to the pressure peaking phenomenon.

The Impact of “Belt and Road Initiative” on Japanese Shipping Law

“Belt and Road Initiative” (BRI) is a Chinese initiative to promote multinational economic cooperation and enhance worldwide prosperity. This Initiative’s impact on other countries’ maritime law and policy is worth exploring. This paper discusses the BRI and its impact on Japanese shipping laws, emphasizing the importance of Sino-Japanese economic cooperation. It is observed that Japanese private enterprises appear to have a more open attitude than that of the Japanese government toward the BRI. By participating in the BRI, Japanese companies can be more involved in international multimodal transport, not only as shippers utilizing the improved rail and sea carriage network to ship their products but also as multimodal transport operators providing logistical services. This may further trigger the development of Japanese shipping law, so that Japan can better benefit from the connectivity brought by the BRI and address new geopolitical challenges created by it.

Checking the adequacy of the method for generating a random process of disturbance of oscillations of rail carriages according to the impulse response of the forming filter

Usually, to study the vibrations of rail carriages, the equivalent geometric unevenness of the track obtained as a result of processing the records of the track measuring car is taken as a disturbance. Such a record contains a certain set of irregularity wavelengths, for example, 50, 25 and 12.5 m. However, when it is used to simulate disturbances at different operation speeds, these wavelengths will correspond to frequencies depending on the given speed of motion, which is not permissible, since a stable frequency range from 0.2 to 10 Hz is required to excite the vibrations of all the bodies included in the carriage. To eliminate this drawback, in the previously performed works it was proposed to generate a random process of geometric irregularities for a given operation speed by changing the set of wavelengths included in the irregularities. In this paper, based on the study of random oscillations of a simplified model of a rail carriage, as a system with one degree of freedom, the adequacy of the method for generating a random disturbance process is verified in two ways. In the first method, it was found that the characteristics of random oscillations of such a model, obtained in the time domain on the basis of numerical integration of the equation of motion when specifying the generated disturbance, have satisfactory convergence with similar characteristics found by the frequency method using Shannon's formula. In the second verification method, the cross-correlation function and the mutual spectral density between the disturbance and the bouncing oscillations were determined from the generated disturbance realization and obtained by numerical integration of the vibration process realization. Then, using the method of identifying the dynamic system, experimental amplitude and phase frequency characteristics were found, which showed satisfactory convergence with the corresponding calculated characteristics obtained by numerically solving the equation of oscillations of the model under study. On the basis of the results obtained, it was concluded that the considered method of generating a random process of disturbance is sufficiently adequate and that it can be applied to solve problems of the dynamics of rail carriages.

Problems of ensuring the acceleration dynamics of aircraft during track tests at a speed of 1600 m/s

The article discusses the problems that arise when creating new models of supersonic and hypersonic aircraft, which can be solved by model high-speed ground track tests. Mathematical modelling of the aerodynamic characteristics of an aircraft (test object) placed on a rail carriage and accelerated by the solid fuel rocket engines is performed. The numerical method solves the problem of the motion of a body of variable mass along a rail track. To determine the required length of the rail track, a mathematical model of the ballistic characteristics of the upper stage of the rocket carriage was compiled, calculations were made, and the influence of various factors on achieving the maximum speed of the test object was analysed. An analysis is made of the influence of the total mass of the carriage with the load and engine thrust on the possibility of accelerating the test object to the Mach speed (4-5).

DETERMINATION OF THE STABILITY OF FREIGHT CARS TAKING INTO ACCOUNT THE RAILWAY TRACK PARAMETERS

Purpose. For prospective speed increase in the work is aimed to consider the complex conditions of the dynamic interaction of the railway track with rolling stock. The nature and level of this interaction depends both on the design of the unit of rolling stock, its state and speed, and on the design and condition of the track itself. Methodology. Evaluation of the possible rolling stock impact on the track was investigated by the analytical method. The track stress state was determined by calculation using dependencies between force factors and the characteristics of the stress-strain state of the track. When determining the static pressure of the wheel on the rail, the influence of rolling stock skews in the rail track according to the “herringbone” scheme is considered, in which the additional lateral effect of the wheel pairs of the bogies on the track structure is maximal. Findings. When conducting theoretical studies, the dependencies of the lift resistance coefficient by longitudinal forces were obtained taking into account various types of inertia forces on irregularities both on the wheel and on the rail thread. The values of the friction coefficient in the wheel-rail contact on the movement speed were also obtained. Originality. For the first time, the rules for calculating the railway track for strength and determining the dynamic loading of the rail carriage are combined. This improvement will make it possible to calculate the structural speed of the car based on the axial loads, inertia forces due to the wheel and rails` irregularities, and also take into account the longitudinal quasistatic forces arising in the train during braking modes. Practical value. Determination of the car lift resistance coefficient using the above methodology will allow a more thorough consideration and justification of the cause of wheelset derailment. The application of this calculation method will allow us to determine the strength of the railway track and the ballast layer, taking into account the uneven load of rail threads in the case of distortions of the freight rolling stock under the action of compressive quasistatic longitudinal forces.

Development of new polymer composite materials for the flooring of rail carriage

The subject of improving the competitiveness and efficiency of railway rolling stock is highly demanded as the railway transport consider the nerve of the goods transport in the hole word. One of the requirements to develop the railway transport related to the continuous improvement of existing materials and find a new material which would satisfy such conflicting requirements as relia-bility, sustainability, producibility and the manufacturing process automation possibility. The researches show that use of polymer composite materials (PCM) in the production of both passenger and freight railway rolling stock, provides lightweight, improves its performance, increases durability and reduces operating costs.Â

Method of Improvement of Efficiency Transportation Technology

This article analyzes the main factors that cause local wagons to stay on the rail when it comes to freight wagons, and develops technological processes for the processing of trains on technical stations. A formula for determining the total number of shipments from the station is also proposed. The interrelation of the operations carried out during the interval between train departure stations to the established stations, and the method of finding the overestimated hours during the operation of inter-sectional distance. The authors have developed a formula for determining the total number of operations from train stations to the designated stations, as well as an algorithm for calculating rail carriages from station to station.

RESEARCH OF WHEEL-RAIL WEAR DUE TO NON-SYMMETRICAL LOADING OF A FLAT CAR

Purpose. The paper is aimed at determining the influence of non-symmetrical loading of a flat car on the magnitude of the wear factor of a wheel-rail pair when changing the operation parameters that occur in operation. Methodology. The dynamic loading of the flat car, model 13-401 with typical three-piece bogies is studied using a model of spatial oscillations of a five-car coupling with the help of mathematical and computer simulation. Theoretical calculations are performed for the most dangerous sections of the railway track – small and medium radius curves in the range of permissible speeds. Findings. The indicators of wear of the rolling stock wheels and the rails are analysed on the example of flat cars in the presence of a longitudinal and transverse displacement of the load mass centre relative to the car symmetry centre. To obtain information on the effect of permissible deviations of the arrangement of cargo in the car on the magnitude of the dynamic loading of the wheel-rail contact, the authors performed theoretical studies of the spatial variations of the rail carriage and its interaction with the track. Originality. To determine the wear of the wheel-rail pair, the effect of displacement in two directions from the central axis of symmetry of the load gravity centre was studied, taking into account the value of the travel speed along the curved sections of the small and medium radius using a mathematical model of coupling of five freight cars. Practical value. As a result of the theoretical studies carried out, the authors assessed such factors as wear factor, directional force, and hunting of the wheel set of freight rolling stock in the event of load gravity centre displacement when moving along curved sections of the railway track. To establish the possible cause of intensive wear of the wheels and rails, the following parameters were analysed: lozenging of front bogie side frames; hunting of the left side frame of the front bogie; mutual longitudinal movement of the side frame and axle box of the front wheel set; mutual hunting of the left side frame of the bogie relative to the front wheel set.

The distribution and influential factors of PM2.5 and CO2 in urban rail carriages

The promotion of ‘Green Transport’ has increased the importance of urban rail transit in China. Increased passenger flow and longer travel time have led to increased attention to in-carriage air quality in trains. In this study, CO2 and PM2.5 monitoring were conducted in subway train carriages in a city in northern China. The study accounts for a variety of factors both inside and outside of the train carriages, such as passenger volume and exterior environment. The results reveal that good air quality outside of the train, an above ground location and the use of platform screen doors could aid in the attainment of acceptable PM2.5 concentrations. In addition, linear models of CO2 and PM2.5 concentrations were established based on passenger density. The nonlinear recursive models were constructed using time-series analysis to reflect the cumulative effects of the amounts of CO2 and PM2.5. The spatial and temporal distributions show that, given a constant passenger density, the PM2.5 concentration is higher near the door area than in the seating area. CO2 concentrations varied in three stages, consistent with the change of local passenger load. Finally, a real-time optimized control method for fresh air volume and some suggestions are proposed to improve the in-carriage air quality of subway trains.

Академік Всеволод Арутюнович Лазарян (1909‒1978) ‒ вчений, педагог, організатор науки і освіти (до 110-річчя від дня народження)

This article depicts the main stages of life, research and scientific, scientifically-organizational, pedagogic and public activity of the outstanding national scholar in the area of mechanics and railway transport, National Ukrainian prize-winner, academician of the Academy of Sciences of Ukraine - Vsevolod Arutyunovich Lazarian. This article indicates that he is the author of more than 300 published works in the field of mechanics- monographs, articles, manuals, and more than 20 invention certificates and patents. The theoretical studies of transitional modes of trains of V. A. Lazarian has always been supported by experimental research in trains and staging in test laboratories for experiments on electronic models of rolling stock.The work of V. A. Lazarian is also essential for practice, in which transition modes of motion of complex mechanical systems are investigated, with elements in the form of capacities, which are partially filled with liquid. The results of studies of transitional modes of trains are described and summarized in the monograph V. A. Lazarian"Investigation of Unspecified Traffic Train Mode", as well as in a number of articles. The great importance to theory and practice had the creation of V. A. Lazarian the theory of stability of motion of rail vehicles. Relying on the results of fundamental research of O. M. Liapunov in the direction of stability of movement, V. A. Lazarian has developed and used a number of methods for studying the stability of the movement of rail carriages. These methods allowed not only to develop engineering methods for assessing the stages of stability of the existing types of rolling stock, but also to put and solve the problem of finding such parameters of vehicles, in which their motion is stable in a given range of speeds. And these studies were supported by well-established experiments. 1972-1973 years under the guidance of V.A. Lazarian tests of a high-speed wagon-lab were carried out, during which for the first time in the former USSR the speed of rail transport was reached 250 km/h. Parameters of the spring suspension of the tested wagon-lab were determined earlier by V.А. Lazarian and his students on the basis of the developed theory of the stability of movement of rail carriage. They were such that the carriage movement, as it turned out from the theory, proved to be stable throughout the range of speeds. There was also a series of special experiments in which a high-speed wagon-lab with some structural changes was used. The results of these experiments convincingly confirmed the main provisions of the theory.

Integration of car-body flexibility into train–track coupling system dynamics analysis

ABSTRACTThe resonance vibration of flexible car-bodies greatly affects the dynamics performances of high-speed trains. In this paper, we report a three-dimensional train–track model to capture the flexible vibration features of high-speed train carriages based on the flexible multi-body dynamics approach. The flexible car-body is modelled using both the finite element method (FEM) and the multi-body dynamics (MBD) approach, in which the rigid motions are obtained by using the MBD theory and the structure deformation is calculated by the FEM and the modal superposition method. The proposed model is applied to investigate the influence of the flexible vibration of car-bodies on the dynamics performances of train–track systems. The dynamics performances of a high-speed train running on a slab track, including the car-body vibration behaviour, the ride comfort, and the running safety, calculated by the numerical models with rigid and flexible car-bodies are compared in detail. The results show that the car-body flexibility not only significantly affects the vibration behaviour and ride comfort of rail carriages, but also can has an important influence on the running safety of trains. The rigid car-body model underestimates the vibration level and ride comfort of rail vehicles, and ignoring carriage torsional flexibility in the curving safety evaluation of trains is conservative.

The Holocaust and Humanity

The Holocaust and Humanity

On-road PM2.5 pollution exposure in multiple transport microenvironments in Delhi

Abstract PM2.5 pollution in Delhi averaged 150 μg/m3 from 2012 through 2014, which is 15 times higher than the World Health Organization's annual-average guideline. For this setting, we present on-road exposure of PM2.5 concentrations for 11 transport microenvironments along a fixed 8.3-km arterial route, during morning rush hour. The data collection was carried out using a portable TSI DustTrak DRX 8433 aerosol monitor, between January and May (2014). The monthly-average measured ambient concentrations varied from 130 μg/m3 to 250 μg/m3. The on-road PM2.5 concentrations exceeded the ambient measurements by an average of 40% for walking, 10% for cycle, 30% for motorised two wheeler (2W), 30% for open-windowed (OW) car, 30% for auto rickshaw, 20% for air-conditioned as well as for OW bus, 20% for bus stop, and 30% for underground metro station. On the other hand, concentrations were lower by 50% inside air-conditioned (AC) car and 20% inside the metro rail carriage. We find that the percent exceedance for open modes (cycle, auto rickshaw, 2W, OW car, and OW bus) reduces non-linearly with increasing ambient concentration. The reduction is steeper at concentrations lower than 150 μg/m3 than at higher concentrations. After accounting for air inhalation rate and speed of travel, PM2.5 mass uptake per kilometer during cycling is 9 times of AC car, the mode with the lowest exposure. At current level of concentrations, an hour of cycling in Delhi during morning rush-hour period results in PM2.5 dose which is 40% higher than an entire-day dose in cities like Tokyo, London, and New York, where ambient concentrations range from 10 to 20 μg/m3.

Stresses in a Bogie Frame of a Rail Carriage

The paper presents a comparative study regarding the distribution of stresses and strains in a bogie frame, a prototype used in plants for the transportation of liquid cast iron, for a case of loading corresponding to common working operating conditions. The results of a numerical analysis carried out using the three-dimensional finite element method and those of an experimental study using the strain gauge technique were compared. Agreement between calculated and measured results obtained was good and areas of the bogie frame with maximum stress were predicted with reasonable accuracy. Knowing the most dangerous stress concentration zones, a new design optimization process could be accelerated without becoming unreliable, ensuring thus a safe transportation of cast iron by rail.