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The indicators of dynamic qualities that ensure the traffic safety, as well as the permissible impact on the railway track, with the obligatory fulfillment of which the railway rolling stock can be used in the transportation process, are presented in this article. The purpose of this work was to carry out the complex dynamic (running), and the impact on the railway track, tests of the rolling stock, during which simultaneous registration of dynamic processes on the railway rolling stock, and in the elements of the superstructure of the track, is carried out, as well as in elements of turnouts. Dynamic tests were carried out on the track switches from the minimum speed to the maximum possible speed of 50 km/h by the TE33A diesel locomotive during the freight traffic. Meeting the requirement of reproducibility of test conditions and having a typical design of the track structure on wooden or reinforced concrete sleepers. [ABSTRACT FROM AUTHOR]

Multibody simulations are widely used for the dynamic analysis of railway vehicles, including the acceptance of vehicle running behaviour. Among these, the freight vehicles have, generally, friction damped suspensions for which numerical modelling is particularly challenging due to the contacting geometries, the intermittent contact, and the frequent stick-slip transitions. The impact of modelling decisions of friction-damped suspensions on the acceptance quantities for vehicle behaviour is the focus of this work. The selection of friction models and tuning of their parameters is challenging. In particular, the selection of friction coefficients is not straight forward, as friction conditions vary during operation and over time. This work aims to address both problems. A model of a friction-damped freight locomotive is used to simulate the dynamic response of the vehicle under realistic operation conditions and assess the impact of the friction modelling decisions. The results show that the use of different friction models provides similar results if the parameters are appropriately tuned. In contrast, the selection of friction coefficients significantly impacts the acceptance quantities, with emphasis on the wheel-rail forces at small radius curve transitions. The results recommend that the standard should include variations of the friction coefficients used for the friction-damped suspensions. [ABSTRACT FROM AUTHOR]

A clean solar hydrail, a locomotive operated by solar and hydrogen energy, has received significant attention as an alternative to a current fossil fuel-based locomotive. Nevertheless, the feasibility test of solar hydrail is still challenging since it has not yet been practically developed. Herein, we employed digital twin technology to design and operate solar hydrail and diesel locomotive. 30 years of operation simulation starting from 2021 was conducted based on the data of Gangwon-do, South Korea. It was confirmed that replacing the single diesel locomotive with solar hydrail can provide about 59 % lower net present cost and annual harmful emission reduction of approximately 300 tons. Sensitivity analyses were also conducted to mitigate future uncertainty, and the solar hydrail was a better option than the diesel locomotive in every scenario. This study demonstrates that solar hydrail is the successful substitute for the diesel locomotive currently operated in South Korea. • 30 years of operation was simulated for solar hydrail and diesel locomotive. • Solar hydrail can have $2,026,279 lower NPC than diesel locomotive. • Solar hydrail yearly saves about 300 tons of emissions compared to diesel locomotive. [ABSTRACT FROM AUTHOR]

This is a communication from a case study of twelve Brazilian freight transportation railroads showing the feasibility of hydrogen-powered locomotives over diesel-powered locomotives. Load increase models are made up to 2035 to project the performance of locomotives and their impacts on these railroads. Eight types of diesel locomotives were chosen for comparison. Interesting finding is that higher specific consumption has lower capacity to haul a heavier load per unit of locomotive power. Trend lines found indicate a reduction of 48% in energy demand if hydrogen is adopted. Results suggest environmental gains, with a reduction in total emissions of 132 kt CO 2 /year by 2035. A variable was created ("Hydrogen Specific Consumption 4k – HSC4k"), which shows the consumption of hydrogen as a function of the distance of the section traveled and the power of the locomotive employed. The methodology proposed is replicable to any rail environment if the indicated data is available. [Display omitted] • 12 stretches and eight types of diesel-powered locomotives served as base comparison. • Energy demand in railways can be reduced up to 48% in 2035 if hydrogen is employed. • Mitigation of 132 ktCO 2 /year is possible if locomotive diesel is switched by hydrogen. • A maximum of 62 tkm/MJ for energy efficiency in the rail freight can be observed. • Hydrogen Specific Consumption – 4k variable was discovered and successfully applied. [ABSTRACT FROM AUTHOR]

At present, the research on crashworthiness of locomotive mainly adopts the method of theoretical analysis, numerical simulation and component test, it is too expensive and less repeatable to carry out vehicle crash tests. Therefore, a method to construct the collision equivalent scaled model (SM) for locomotive based on multi-parameter nondimensional is presented in this paper. Firstly, an equivalent method of structural dynamic responses was proposed. The extraction process and analysis method of dynamic responses for thin plate structures widely existing in locomotives were studied. Then, according to the structural characteristics of the locomotive, the partition equivalent design was carried out, and a dimensionless analysis model of impact dynamic responses for SM was established. Finally, the SM crash test was carried out to verify the effectiveness of collision equivalent SM established, it was found that the SM has high reliability, it can achieve equivalence with the locomotive for energy absorption, average impact force, average acceleration of cab and center of gravity of vehicle body. Carrying out the SM crash test can study the reasonable configuration of energy absorption parameters for locomotives and obtain the impact dynamic responses of locomotives under different configurations of energy absorption parameters. [ABSTRACT FROM AUTHOR]

Fuel Hydrogen cells become nowadays a major candidate to replace the diesel in powering the traction locomotives since they offer low emission of pollutant gases, high efficiency, and flexible modular structure without the need for installation of electrification infrastructure for railway networks. However, they cannot respond appropriately to the fast load transients due to their slow internal electrochemical and thermodynamic responses. Therefore, they shall be integrated with fast dynamics Li-ion battery cells to form a hybrid power source for traction systems. Accordingly, this paper presents a development of a new smart integrated power source of fuel hydrogen and Li-ion battery cells to supply dual three-phase machines for driving the trains in railway networks. The developed control management system is regulating the two power sources according to the train operational modes as well as the battery state of charge. In addition to that, dual three-phase machines offer several superiorities over the conventional three-phase machines such as lower harmonic distortion and power losses along with higher power density and fault tolerance. A designated railway line is nominated through selection criteria in this paper for the implementation of the new smart drive traction system in HIL platform using Typhoon HIL real time simulator. Moreover, an optimization analysis has been carried out to reduce the overall hydrogen consumption with the same journey time spent for a designated railway line using particle swarm optimization approach. Finally, a case study is presented to illustrate a proof of concept for designing the hydrogen refueling station for such railways which are supplied by the new integrated power source of fuel hydrogen and Li-ion battery cells. The case study investigates the site selection, operational assessment, and equipment requirements. • Smart hybrid power source of fuel hydrogen and Li-ion battery cells is developed to supply dual three-phase machines for driving the trains. • The management system regulates the power sources according to the train operational modes as well as the battery state of charge. • The new drive traction system is validated in hardware-in-the loop platform using Typhoon real-time simulator. • Optimization analysis is also carried out to reduce the overall hydrogen consumption using particle swarm optimization approach. • Li-ion battery cells are optimized to act as an energy storage buffers by keeping their states of charge at start and end of the journey the same. [ABSTRACT FROM AUTHOR]

Adding battery locomotives to traditional diesel locomotives to form a hybrid consist has the potential to reduce fuel consumption and emissions in freight rail operations. This paper provides route-based estimates of diesel (hpd/ton) and battery (hpb/ton) power requirements and diesel (gal/ton) and battery (hpbhr/ton) energy requirements for hybrid consists. Given a route-specific power profile, the power split between the battery pack and the diesel engine is optimized to minimize fuel consumption by running the diesel engine at maximum efficiency during the entire route. Simulations for 200-mile round trips between Chicago and Harrisburg show that the diesel power is maximum in low-gradient regions at 1.05 (hpd/ton) and battery power is maximum in hilly regions at 2 (hpb/ton) for discharge and 6.5 (hpb/ton) for charge. Maximum fuel efficiency gains of approximately 60% are seen in the mountains, where 2.09 (hpbhr/ton) of battery energy is needed. Minimum fuel economy gains are observed in flat regions, with 20% fuel consumption reduction. With battery current and voltage limits, the battery pack size increases, and fuel savings decrease. [ABSTRACT FROM AUTHOR]

The work considers the problem of determining the factors of energy efficiency of industrial parks in the conditions of military aggression in the conditions of the introduction of the National Economic Strategy and regulatory influence on Industrial Parks in Ukraine. The energy efficiency of industrial parks primarily depends on the main parameters of the selected technological processes that are embedded in the basis of enterprises and their productivity. A significant factor affecting the environmental friendliness and energy efficiency of industrial parks is the method of energy generation. On the basis of the analysis of the work of enterprises operating in conditions of military aggression, the main factors determining the energy efficiency of electricity production have been determined. Such factors are the overall efficiency of the power generating unit, which is determined by monitoring and diagnosing the power unit. Analyzing changes in energy efficiency, the characteristics of the power part of one of the most powerful diesel engines were selected. It is obvious that the diesel locomotive will consume more fuel to generate energy with a decrease in efficiency. The main diagnostic factors of generating equipment that affect the energy efficiency of industrial parks in conditions of military aggression are: the ratio of currents in compressor and depressurized modes, the real degree of compression, and as a result, the efficiency of the power plant. On the basis of the determined factors, the effectiveness of the implementation of the system of monitoring and diagnosing the power units of energy-generating equipment of enterprises in the conditions of military aggression was determined. Recommendations have been established to minimize fuel consumption and reduce emissions to ensure the main principles of industrial parks, environmental friendliness and energy efficiency. [ABSTRACT FROM AUTHOR]

The work considers the problem of determining the factors of energy efficiency of industrial parks in the conditions of military aggression in the conditions of the introduction of the National Economic Strategy and regulatory influence on Industrial Parks in Ukraine. The energy efficiency of industrial parks primarily depends on the main parameters of the selected technological processes that are embedded in the basis of enterprises and their productivity. A significant factor affecting the environmental friendliness and energy efficiency of industrial parks is the method of energy generation. On the basis of the analysis of the work of enterprises operating in conditions of military aggression, the main factors determining the energy efficiency of electricity production have been determined. Such factors are the overall efficiency of the power generating unit, which is determined by monitoring and diagnosing the power unit. Analyzing changes in energy efficiency, the characteristics of the power part of one of the most powerful diesel engines were selected. It is obvious that the diesel locomotive will consume more fuel to generate energy with a decrease in efficiency. The main diagnostic factors of generating equipment that affect the energy efficiency of industrial parks in conditions of military aggression are: the ratio of currents in compressor and depressurized modes, the real degree of compression, and as a result, the efficiency of the power plant. On the basis of the determined factors, the effectiveness of the implementation of the system of monitoring and diagnosing the power units of energy-generating equipment of enterprises in the conditions of military aggression was determined. Recommendations have been established to minimize fuel consumption and reduce emissions to ensure the main principles of industrial parks, environmental friendliness and energy efficiency. [ABSTRACT FROM AUTHOR]

This paper mainly studies the safety and cost control challenges faced by diesel locomotives operating in cold environments. In order to meet this challenge, the author solves the fuel system problem of railway diesel locomotive in cold environment by deeply understanding and optimizing the chemical properties of fuel oil, and by designing and implementing effective heating system. First, the author investigates and summarizes the chemical properties of the fuel and the ambient temperature required for the fuel. The change of chemical properties of fuel under normal and low temperature is verified by experiments, and the specific demand relationship between the safe operation of railway diesel locomotive and the chemical properties and temperature of fuel is clarified. These implements provide strong data support for the realization of low fuel combustion. Subsequently, based on the above research results, the author designs a fuel temperature control system that can meet the low-burning fuel demand. In the design process, the chemical properties of fuel and the particularity of the material and structure of fuel tank in a railway diesel locomotive are fully considered, and a fuel heating scheme is proposed. Finally, it is verified by actual measurement that the scheme has the ability of fine control of temperature and synchronous heating of multi-temperature zones, which meets the actual demand of low fuel combustion. [ABSTRACT FROM AUTHOR]

The individual drive of the axles of a vehicle produces a reduction of the axle adhesion, implicitly reducing the total traction force of the vehicle. The paper proposes eliminating load transfer effects by using an algorithm to redistribute the traction effort between the tractive axles equipped with electric traction motors. A case study is presented, using the balancing of the electric traction torque for an electric locomotive, using the load transfer effects compensation. The conclusions can be used to maximise the traction of all types of vehicles, such as trailers, hybrid tractors, large harvesters, and Diesel-electric locomotives. [ABSTRACT FROM AUTHOR]

The derailment of railway vehicles in the turnout area is a worldwide concerned issue. Previous studies mainly concentrate on the derailment at the switch area, and the risk at the frog area is seldom concerned. Based on a specific derailment case of the remote locomotive in a 20,000-tonne heavy-haul train, a study on the derailment of the locomotive at the turnout frog area is presented. The conditions of the derailed locomotive and turnout track are introduced, and the potential influence factors are screened according to the field investigation results. A detailed simulation model that considers the complex wheel-frog/guard rail contact relationship and the interaction between adjacent vehicles is established. Through numerical simulation, the derailment process of the locomotive at the turnout frog area is reproduced, and the derailment mechanism is revealed, followed by the influence analysis of the potential factors. The results indicate that the combined effect of the compressive coupler force and the coupler jack-knifing promotes the derailment remarkably. Moreover, the derailment at the turnout frog area is more likely to occur under low-speed conditions, and the possibility of derailment can be reduced by decreasing the compressive coupler force and the friction coefficients between the wheel and stock/frog/guard rail. [ABSTRACT FROM AUTHOR]

Excessive crosstie wear and abrasion and ballast wear and fouling are fundamental problems contributing to inadequate railroad track performance. This adversely affects the attainment and long-term maintenance of desired track geometric requirements. The magnitudes and distribution of the stresses at the crosstie-ballast (CT-B) interface must be known to determine the stress distribution on and within the ballast. However, the track design recommendations to determine these pressures, which are largely based on a methodology from the 1980s, are currently valid for modern-day railroad applications for multiple reasons discussed in this study. This study analyzed CT-B interfacial pressure data measured on an active freight mainline in Mascot, Tennessee. Dynamic contact pressures at the CT-B interface were measured using hydraulic earth pressure cells for various wheel loads and train speeds. The test train was a Federal Railroad Administration (FRA) test train consisting of a diesel electric locomotive, a test car that had different wheel loads based on the deployable axle load, and an inspection car. Although the maximum train speed was limited to 64 km=h, this research found that speed variation has a minimal effect on the CT-B interfacial pressures. From the measured data, a Gaussian stress distribution equation is proposed to determine longitudinal pressure distribution transmitted to the CT-B interface for static conditions. In addition, the stress distribution along the length of a crosstie was investigated via laboratory experimentation using a half-length crosstie. As a result of the experimentation, a dimensionless trilinear approximation was developed to estimate the stress distribution along the length of the crosstie. In general, this research recommends that the longitudinal and lateral stress distributions be considered together to design a better railroad track. [ABSTRACT FROM AUTHOR]

This article presents a mathematical model of the risk of failures, depending on the operating parameters, of locomotive diesel engines. The purpose of this study is to determine the risk of failures of locomotive diesel engines in maintenance. The theory of probability and the theory of logic and reliability are used in this theoretical study. The innovations and main works are the first approaches to calculating the risk of failures of locomotive diesel engines by hourly fuel consumption, which, under operational conditions, allows for extending the life of locomotive diesel engines during maintenance. As a result, a maintenance process for 5D49 diesel engines is developed in a locomotive depot. When managing the maintenance processes of 5D49 diesel engines in the locomotive depot, it is determined that the optimal mileage is 45,000 km. The resource of 5D49 diesel engines in the locomotive depot increased by 2.4% in the management of the maintenance process compared to the existing maintenance system. [ABSTRACT FROM AUTHOR]

This paper describes the longitudinal-vertical coupling dynamics of a high-speed train rescued by locomotives during the braking process on grades. The coupler jackknifing behaviour under compressive forces will affect the running safety of the coupling train. In this paper, the longitudinal-vertical impacts by field testing for the locomotive to train rescue scenario are firstly introduced. The quasi-static force analyses of the train and couplers are carried out to study the coupler jackknifing mechanism on graded tracks. The three-dimensional dynamic model of the train and coupler system is then developed. In this model, the coupler rotational motions, hysteresis characteristic of draft gears, braking characteristic are taken into account. The typical responses during the braking process for the high-speed train rescued by the diesel locomotive are reproduced and verified. The running safety of the longitudinal-vertical interaction for selected scenarios is further evaluated. The Influences of train speed and track gradient on the longitudinal-vertical dynamics are also studied. Two improvement measures, including the limitation of the coupler pitch angle and coupler force, are discussed to provide possible solutions. [ABSTRACT FROM AUTHOR]

Currently, hydrogen and electric drives used in various means of transport is a leading topic in many respects. This article discusses the most important aspects of the operation of vehicles with electric drives (passenger cars) and hydrogen drives. In both cases, the official reason for using both drives is the possibility of independence from fossil fuel supplies, especially oil. The desire for independence is mainly dictated by political considerations. This article discusses the acquisition of basic raw materials for the construction of lithium-ion batteries in electric cars, as well as methods for obtaining hydrogen as a fuel. The widespread use of electric passenger cars requires the construction of a network of charging stations. This article shows that, taking into account the entire production process of electric cars, including lithium-ion batteries, the argument that they are ecological cannot be used. Additionally, it was indicated that there is no concept for the use of used accumulator batteries. If hydrogen drives are used in trains, there is no need to build the traction network infrastructure and then continuously monitor its technical condition and perform the necessary repairs. Of course, the necessary hydrogen tanks must be built, but there must be similar tanks to store oil for diesel locomotives. This paper also deals with other possibilities of hydrogen application for transformational usage, e.g., the use of combustion engines driven with liquid hydrogen. Unfortunately, an optimistic approach to this issue does not allow for a critical view of the whole matter. In public discussion, there is no room for scientific arguments and emotions to dominate. [ABSTRACT FROM AUTHOR]

Locomotive emissions from railroads can particularly impact air pollution, making it crucial to understand their impacts on human health and the environment and develop strategies to reduce them. The potential of drone technology equipped with a "sniffing" system for detecting air pollution emissions is promising and can be a valuable tool for assessing dynamic emissions. This research utilized sensor-equipped drones to measure gaseous emissions from cargo and passenger trains on a railway in Curitiba, Brazil. Reference equipment evaluated the accuracy of NO2, SO2, and O3 concentrations. The results showed that before the passage of trains, the average SO2 concentration was 20 µg/m³, with a maximum concentration of 110 µg/m³ detected during transit. The average increase in NO2 concentrations was from 30 µg/m³ to 120 µg/m³, and the average increase in O3 concentrations was from 80 µg/m³ to 135 µg/m³. The vertical profiles were evaluated before and after the passage of locomotives, indicating an accumulation of pollutants above the railroad. These findings demonstrate the potential of sniffing drones to measure railroad emissions in urban environments. They also highlight the need to regulate emissions from diesel-powered locomotives to minimize atmospheric pollution and its negative impact on public health in emerging and developing countries. [ABSTRACT FROM AUTHOR]

A successful guaranteed launch of a mainline diesel locomotive is one of the most important and urgent problems of the rolling stock operation. Improvement of the start-up system of the main diesel locomotive when using a supercapacitor allows multiple restarts of diesel locomotives, meaning that the operation of the diesel locomotive can be stopped several times without wasting fuel in idle operations. In this study, we simulated the electric starting circuit of a diesel locomotive with a block of supercapacitors using the Matlab Simulink program. The simulation results show that using only a supercapacitor in the start-up system is impossible. Even though the supercapacitor produces the required current and voltage, its operating time is extremely insufficient. Using a storage battery along with a supercapacitor in the diesel locomotive start-up system is most effective. This reduces the peak current load on the standard battery. The article suggests an effective principle for starting a mainline diesel locomotive and provides an effective circuit solution involving a supercapacitor. Based on the booster stabilizer scheme, a new scheme was modeled to study the successful launch of a diesel locomotive that has various start-up systems. Applying a supercapacitor in the start-up system of a main diesel locomotive is proposed and the results of its use are presented. In addition, this study defines the basic requirements for using a system based on a battery in conjunction with a supercapacitor. Characteristics such as the temperature range of the system are shown. [ABSTRACT FROM AUTHOR]

The present article focuses on the efficient deployment of dual locomotives in regional rail freight transport considering the quantification of traction energy and energy savings. In the first part of the article, a categorization of dual locomotives, according to their power output in electric and alternative traction (and ratio of both power outputs) is proposed. The potential of deployment of chosen dual locomotives in Central European conditions (a sub-network of Czech railway network around mainlines electrified with AC) is verified by calculation of traction energy consumption of the model train (with two examples of dual locomotives). In addition to non-stop running through the entire line, traction energy consumption of stop (and following acceleration) in each intermediate station is calculated, for a particular direction. Then, appropriate freight train paths for passing passenger trains and saving of traction energy are proposed. The results are supplemented by sensitivity analysis in the form of calculation of traction energy consumption with variable numbers of loaded wagons, with the help of iPLAN/FBS timetabling software. The limitations are the maximum length or gross mass of the train. Finally, the conclusions obtained from the computational examples are evaluated and recommendations for appropriate deployment of dual locomotives and planning of targeted improvements of infrastructure are formulated. [ABSTRACT FROM AUTHOR]

Hydrogen electric locomotives are receiving growing attention and progressing towards net zero. This letter discusses the improvement of traditional diesel-electric locomotives to use hydrogen and reduce energy demand. An internal combustion engine featuring direct injection and jet ignition of the hydrogen is proposed. The four-strokes, 12 L, V12 engine achieves peak power of 750 kW and peak efficiency above 46%. The propulsion system may be further optimized by adopting battery energy storage to buffer the operation of the engine and provide extra power when accelerating. This way, the engine may be further optimized to work over a narrower range of speeds and loads and be made smaller to provide reduced power. • Conversion of diesel locomotives to hydrogen is straightforward. • Use of a larger traction battery help with energy recovery. • It also helps using a smaller engine to work more efficiently. • Fuel cell alternative has efficiency advantage, but weight, volume, power density, and TRL disadvantages. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate whether equol production status has an impact on the risk of locomotive syndrome in very elderly (≥85 years old) women. In this retrospective observational study, 116 very elderly women were recruited from those who lived in nursing homes for the elderly from June 2018 to November 2019. Equol production status was determined by measuring spot urine levels of equol, and risks of locomotive syndrome were evaluated by vulnerable fracture history and loco-check, a simple questionnaire comprising seven questions that can describe locomotive syndrome. Equol production (≥1 µmol/L in a spot urine sample) was found in 46 women (39.6%). Loss of equol production contributes to some loco-check items, which correlate with weakness of lower limb muscle strength (P < 0.05). In this study population, 57 women (49.1%) had previous vulnerable fractures. However, equol production status was not significantly related to the vulnerable fracture in this study population (P = 0.159). Equol production might contribute to the induction of locomotive syndrome, at least in part. However, equol deficiency as a mechanism of locomotive syndrome induction might not be the primary cause of a previous vulnerable fracture in very elderly women who live in nursing homes. [ABSTRACT FROM AUTHOR]

In recent years, the number of long-distance trains running on non-electrified lines has been increasing in Poland. Unfortunately, trains running on non-electrified lines, unlike those running on the hook of electric locomotives, are very often canceled, especially in the winter. In this research, the analysis of which lines had the most frequent cancellations of trains in 2021 and the reasons for these cancellations were analyzed. The results show that the most common cause of train cancellations was the lack of an efficient locomotive at the starting station. Most often, accessibility problems concern Czech series 754 diesel locomotives. The numbers of canceled trains in February 2021 and 2022 were also compared. The comparison showed that although the situation is far from ideal, it has improved significantly. [ABSTRACT FROM AUTHOR]

Knowledge of creep forces at wheel-rail interface when high power is applied to the locomotive wheels has been the subject of many recent studies. The common wheel-rail interaction methods are generally divided by two theories – Hertzian and non-Hertzian. The first method uses Hertzian contact for the normal problem and the tangential problem is divided into two algorithms – Polach's theory and the Simplified theory-based algorithm referred to as Modified Fastsim. Kalker's original Fastsim-based method shows a better accuracy for these two Hertzian-based algorithms. The second method is based on the non-Hertzian theory, and it uses the Exact theory also developed by Kalker and implemented in the Extended Contact library to calculate forces at the wheel-rail interface. Considering that the second method is more accurate, this paper aims to present an adaptive simulation and integration method (ASIM) which is positioned in the middle between the two common methods and is designed to introduce a transition from the non-Hertzian to Hertzian contact in the normal problem with the application of the Modified Fastsim for the calculation of contact forces at the wheel-rail interface. The proposed method is aimed to be used in vehicle system dynamics studies performed in multibody software packages. A specially developed wheel-rail coupling incorporating geometrical, normal, and tangential modules is integrated into Gensys multibody software and benchmarked with the standard Extended Contact based wheel-rail coupling by means of locomotive traction tests that use a full mechatronic model of a high adhesion locomotive. The computational performance and accuracy of the proposed method are assessed and discussed. [ABSTRACT FROM AUTHOR]

This paper investigates the longitudinal dynamics performance of the combined heavy haul trains, especially for the cyclic air braking strategy on the long and steep downhill segments. Firstly, the mathematical models for calculating the longitudinal forces in the longitudinal train dynamics simulations are formulated. The brake delay time between neighbouring cars and the pressure variation of the brake cylinders in the braking and releasing processes are considered in the air braking force model. Besides, the nonlinear hysteresis characteristic of the coupler-draft gear system is taken into account in the coupler force model. The Newmark-β method is introduced as a numerical solver in this paper. Finally, the simulations based on the real-word infrastructure and vehicle data of the Shuozhou-Huanghua Line are carried out to study the longitudinal dynamics of the combined heavy haul trains with two distributed locomotives. [ABSTRACT FROM AUTHOR]

Suspension parameters optimisation and matching is a very important topic in the design of railway vehicles, and a reasonable combination of suspension parameters is the most powerful guarantee for safe and stable operation. However, most of the existing research about that still belongs to single-objective optimisation and pays little attention to the matching relationship between different suspension parameters, which has plenty of limitations. Therefore, the lateral stability and ride comfort of a certain type of domestic high-speed locomotive are studied and optimised through the genetic algorithm NSGA-II, to find the optimal lateral dynamic performance. It can be found that there is an obvious contradiction between linear stabilities under low-conicity and high-conicity conditions, but a strong positive correlation between low-conicity stability and lateral ride comfort in a low-conicity condition. Besides, the matching relation of the six key suspension parameters is explored employing data analysis methods, such as global sensitivity and clustering analysis, and three types of parameter combinations are proposed. In addition, the speed robustness and rail cant robustness regarding the three types of parameter combinations are analyzed, and the lateral dynamic performance characteristics of each parameter combination type are summarised. [ABSTRACT FROM AUTHOR]