High-speed Train Operation Research Articles

Interference Elimination of Wall Fluctuation Pressure Test Signal of High-Speed Train Based on Phase Space Reconstruction and Vibration Interference Model

Because of the complexity of high-speed train operation, the measured wall pressure of high-speed train will be affected by many factors, such as train vibration and environmental changes, which make the test signal inaccurate. The main interferences are the electromagnetic interference caused by the complicated electromagnetic environment and the sensor output interference caused by the train body vibration. In this paper, ensemble empirical mode decomposition (EEMD) combined with singular value decomposition (SVD) and the local projection de-noise algorithm with better effect on non-linear time series noise reduction are used to eliminate electromagnetic interference in test signal. Because of the frequency band aliasing of test signal and interference cause by vibration, it is difficult to eliminate vibration interference by the signal processing method. In this paper, a vibration interference model is established by model-train experiment and computational fluid dynamics (CFD) software to eliminate the vibration interference in the test signal. Moreover, the theoretical guidance for accurately extracting the wall pressure of high-speed train has been put forward.

An Improved Faster R-CNN for High-Speed Railway Dropper Detection

Overhead contact systems (OCSs) are the power supply facility of high-speed trains and plays a vital role in the operation of high-speed trains. The dropper is an important guarantee for the suspension system of the OCS. Faults of the dropper, such as slack and breakage, can cause a certain threat to the power supply system. How to use artificial intelligence technologies to detect faults is an urgent technical problem to be solved. Because droppers are very small in whole images, a feasible solution to the problem is to identify and locate the droppers first, then segment them, and then identify the fault type of the segmented droppers. This paper proposes an improved Faster R-CNN algorithm that can accurately identify and locate droppers. The innovations of the method consist of two parts. First, a balanced attention feature pyramid network (BA-FPN) is used to predict the detection anchor. Based on the attention mechanism, BA-FPN performs feature fusion on feature maps of different levels of the feature pyramid network to balance the original features of each layer. After that, a center-point rectangle loss (CR Loss) is designed as the bounding box regression loss function of Faster R-CNN. Through a center-point rectangle penalty term, the anchor box quickly moves closer to the ground-truth box during the training process. We validate the improved Faster R-CNN through extensive experiments on the VOC 2012 and MSCOCO 2014 datasets. Experimental results prove the effectiveness of the proposed network combined with attention feature fusion and center-point rectangle loss. On the OCS dataset, the accuracy using the combination of the improved Faster R-CNN and ResNet-101 reached 86.8% mAP@0.5 and 83.9% mAP@0.7, which was the best performance among all results.

Comfort-aware Cooperative Cruise Control of Multiple High-speed Trains: An Artificial Potential Field Approach

Abstract In this work, the cruise control problem of multiple high-speed trains movements is investigated. Different from the classical PID control method applied in the practical highspeed train operation system, in this paper, a cooperative cruise control strategy considering both safety and passenger comfort based on layered potential function is proposed. First, the cyber-physical modeling of the high-speed trains system is presented, where the physical layer models the dynamic characteristic, and the cyber layer describes the communication topology. Second, a cooperative control algorithm based on layered potential function is designed. The underlying artificial potential function is introduced to keep a safe distance between adjacent high-speed trains, and the speed consensus rule is realized through the consensus algorithm. The hyperbolic tangent function is selected as the upper artificial potential function to ensure the acceleration of the high-speed train within a comfortable range. Finally, the stability of the control system is proved by the Lyapunov stability theorem, and simulations verify the effectiveness of the control strategy.

A finite element analysis-based study on the dynamic wheel–rail contact behaviour caused by wheel polygonization

In this study, an explicit finite element analysis method was adopted to investigate the wheel–rail impact response generated by wheel polygonization, using a three-dimensional wheel–rail rolling contact finite element model. In this model, the infrastructure below the rails and the stiffness and damping of the sleeper supports were considered. Then, the characteristics of the wheel–rail contact zone, the stress/strain state and the wheel–rail impact force of the polygonal wheel–rail system were presented and discussed and were compared with those of the ideally perfect wheel–rail system. A parametrical study was then carried out to examine the influences of train speed and the polygonal order of the wheel on the wheel–rail impact response. The finite element analysis results revealed that the vertical wheel–rail impact force induced by wheel polygonization is related to the wheel radial deviation; the maximum contact force, stress and strain are all elevated with the increase of the order of the polygonal wheel, which suggested that the wheel should be repaired when it is in the initial lower order polygonal state. These findings can provide some theoretical and technical support for the optimal design of the wheel–rail system and the safe operation of high-speed trains.

Research on opportunities of operation of speed passenger trains by the couple unit system on the railway of ukraine

In the work investigated the direction of introduction of technology for the organization of multiply-units speed trains, which will reduce the cost of developing variable demand of train routes, and improve the quality of passenger service. In order to increase the efficiency of transportation in high-speed trains, it is necessary to use organizational technologies, which are based on concepts, that meet the requirements of the variable basis of the organization of passenger transportation and allow to provide a flexibility for companies-carriers. Was analyzed experience of operating high-speed electric trains on multiply-units control system. The modular operation of high-speed trains offers the ability to combine trains into two or even three trains with the possibility of adapting to changing time and space requirements. This makes it possible to use short-haul trains, which can be combined with trains of higher complexity to meet variable demand on railway network. In the work we find a solution for the problem of constructing a plan for the formation of connected high-speed trains on the network graph, and proposed an improved model of the current variant of the Intercity+ high-speed train on the Kiev-Przemysl route using connecting two high-speed trains.

Hardness ratio optimization of HiSi wheel/U71MnG rail tribo-pairs by sliding wear for high-speed train

Hardness matching of wheel and rail steels is important for the economic and safe operation of high-speed trains. A new wheel steel named HiSi has been developed by our group recently. Thus the aim of this paper is to explore the optimal hardness ratio of Hw/Hr for HiSi/U71MnG tribo-pairs. Therefore, HiSi wheel steels with various hardness were prepared by tempering at 500 °C–660 °C. Then microstructure and mechanical properties including hardness, strength, elongation and absorbed energy was evaluated with the comparison of ER8 and U71MnG. With the increase of tempering temperature, cementite morphology was transformed from lamellar cementite to plate cementite then to spheroidized cementite, which improved the ductility and toughness of HiSi steel. Furthermore, the sliding wear test under the hardness ratio of 0.91–1.11 revealed that the optimal Hw/Hr in HiSi/U71MnG tribo-pairs was about 0.98–1.04, which can be attributed to the ploughing damage without material remove, more adhesive films and suitable mechanical properties of HiSi steel tempered at 560°C–620°C.

Experimental and Numerical Investigation on Repairing Effect of Polymer Grouting for Settlement of High-Speed Railway Unballasted Track

Uneven settlement of high-speed railway subgrade leads to the irregularity of high-speed railway line, which seriously affects high-speed train operation. The skylight point of high-speed railway operation is short and the maintenance time is limited. Therefore, how to quickly lift and repair the ballastless track slab in the subsidence section is an urgent problem to be solved in the maintenance of high-speed railways. The two-component non-aqueous reactive polymer material has the advantages of strong expansive force, fast reaction speed, and wide application range, which is extremely suitable for the repair of high-speed railway track slab subsidence and lifting. In this study, the expansion force characteristics of different density polymer materials and the stress-deformation curves at corresponding density are tested in laboratory to propose the mechanical parameters of polymer. Then, a three-dimensional finite element (FE) model of high-speed railway train ballastless-track subgrade is established based on ABAQUS. The mechanical characteristics of CRTS III ballastless track under different repair materials, different elevation, and different density of polymer grouting materials are analyzed. The results show that, under the dynamic load of the train, the stress value of polymer repairing material is less than that of cement slurry, presenting a compressive stress state, which is similar to that of the complete subgrade surface. In addition, within a certain thickness range, increasing the thickness of polymer is beneficial to reducing the difference of stress variation between polymer filling layer and complete pavement. Once beyond this range, the thickness of polymer has little effect on the force variation.

Research on rolling bearing fault diagnosis of high-speed train

The rolling bearing is the main vulnerable component of a rotating machinery on high-speed train, which is very important to the safe operation of high-speed train. Based on the fundamental analysis of the causes of rolling bearing faults on high-speed trains, the feasibility of wavelet packet analysis and BP neural network in rolling bearing fault diagnosis of high-speed trains is discussed. In this paper, wavelet packet is used to denoise data and extract features, then the training BP neural network is used to diagnose and analyze the characteristic data accurately, and the diagnosis results are obtained. By comparing the training results, the number of wavelet packet decomposition is determined, and the accuracy of BP neural network diagnosis is improved. In this paper, the analysis is carried out by using the bearing data of American electrical laboratory “Case Western Reserve University”, an efficient and fast method for rolling bearing diagnosis is presented, which can be applied to real-time fault diagnosis and monitoring of rolling bearing faults for high speed train.

PAC Interaction Inspection Using Real-Time Contact Point Tracking

A good on-line contact, characterized by high-precision measurement, between the pantograph and catenary (PAC) ensures the safety of PAC and subsequently high-speed train operation. Currently, image processing is the mainstream measurement method for detecting contact points, in which the contact point’s real-time tracking in the image sequences with complex background is the method’s core difficulty. In this paper, a contact point surveillant method that can run during the actual operation of the railway is proposed. This surveillant method can be initialized by the global robust detection method and can do real-time tracking by means of kernelized correlation filters, which has high stability in regional tracking. With the help of result refinement and result confidential evaluation methods, this surveillant method can stably and independently obtain real-time and accurate results, which further gives the state analysis based on 3-D positions. The proposed method is tested on image data sets collected from a high-speed train running at 200 km/h, and results corroborate that a high-speed, high-precision, and stable contact point tracking is achievable, which ensures the state measurement’s feasibility by means of the contact point trajectory.

Evaluating frost heave susceptibility of well-graded gravel for HSR subgrade based on orthogonal array testing

Abstract Well-graded gravels are usually considered non-frost-susceptible, which appears to be a fair assumption in accordance with universally recognized frost criterions; However, their frost heave susceptibility is affected by the unavoidable presence of fines (passing through No. 200 sieve, 0.075 mm) and water when used as backfills for high-speed rail (HSR) subgrade. In practice, non-negligible frost heave would occur within gravels throughout a severe winter, causing great difficulties for operation and maintenance of high-speed trains which tolerates a maximum heave amount of 5 mm. This paper introduces a series of unidirectional freezing tests performed on gravel soils that rely on an orthogonal array, and the frost heave properties of tested material were obtained under the combined effect of moisture content, fines content, dry density, and cooling temperature. The average heaving ratio (AHR), an indication of frost heave susceptibility, was estimated by multivariate regression analysis using a stepwise approach. The results suggest that moisture content exerts the greatest influence on average heaving ratio of well-graded gravels, followed by dry density, fines content, and cooling temperature. In addition, whether the dry density is positively or negatively related to an average heaving ratio depends on the levels of fines content and cooling temperature. A statistical model considering the interaction between factors is proposed to predict the average heaving ratio and to evaluate the frost heave susceptibility of well-graded gravels further.

Feasibility verification for anomaly detection of track structures based on vibration data form vehicle body

Strengthening the detection and monitoring of abnormal track structure is of great significance to ensure the good operation of high-speed trains. The feasibility of detecting abnormal track structure of lower structure based on vehicle body vibration acceleration is verified numerically in this paper. A passenger car model is firstly established by rigid body dynamics software SIMPACK, and the vibration response of the car body is obtained by adding the abnormal irregularity waveform of typical track on the track spectrum as the wheel-rail excitation. And then, by comparing the acceleration vibration response of different positions and directions on the car body, the optimal measuring point of vibration sensor on the car body is determined. The results show that the vertical vibration acceleration of the front and rear position of the car can effectively reflect the abnormality of the lower track structure. Using the vibration data of the car body as the medium can provide a new way for the rapid abnormal detection of the lower track structure.

Study on Optimization of automatic train operation based on Grey genetic algorithm

The speed controller is the kernel module of Automatic Train Operation system, and is also a key core technology of the intelligent high-speed train. The research of the intelligent speed controller of ATO system is of great significance for automatic high-speed train operation. Through the analysis of the principle and function of CTCS-3 system, the scheme of adding the speed controller of ATO system in CTCS-3 system was proposed. The connection way between the speed controller of ATO system and ground equipment was designed to realize information interaction. The model of speed controller of ATO system for high-speed trains which is researched by grey system theory was used for prediction and decision making. In the grey prediction module, the metabolic GM (1,1) model was established, and the optimal strategy was generated by the multi-objective intelligent weighted grey target decision. Finally, a reasonable control strategy of train automatic operation was obtained. The optimal control strategy was got by using genetic algorithm. Designing software for the simulation test, the simulation results show that the method achieves automatic high-speed train operation under the CTCS-3+ATO system through the actual line data, and the efficiency of train operation, the energy saving index and all the performance indexes of the train were improved.

Neural Adaptive Fault Tolerant Control for High Speed Trains Considering Actuation Notches and Antiskid Constraints

Automatic operation of high speed trains (HSTs) requires dedicated control schemes to tackle uncertain dynamics, unknown resistive forces, coupling nonlinearities, interactive in-train forces, unexpected disturbances, and faults. This paper addresses the problem of position and velocity tracking control of HSTs with multiple vehicles connected through elastic couplers. A neuro-adaptive fault tolerant control scheme is developed to compensate the input nonlinearities due to traction or braking notches, uncertain impacts from in-train forces, resistive aerodynamic drag forces, traction or braking faults, and adherence-antiskid constraints. High precision velocity and position tracking is achieved by using the proposed control scheme that combines the robust adaptive control with nonlinearly layered neural networks. Closed-loop stability is ensured with strict mathematical analysis. The effectiveness of the proposed approach is also validated through numerical simulations with considering the adherence-antiskid constraints.

High efficient dynamic analysis of vehicle–track–subgrade vertical interaction based on Green function method

ABSTRACTA new method is proposed to efficiently simulate vehicle-track-subgrade vertical dynamic interactions based on the Green function method. In this simulation, the vehicle-track-subgrade system is divided into two subsystems, the vehicle-rail subsystem and the slab-subgrade subsystem, which are coupled through fastener connections. In the vehicle-rail subsystem, the vehicle is modelled as a multi-rigid-body system with 10 degrees of freedom, and the rail is simplified as a Bernoulli-Euler beam supported by rail pads. Dynamic equations of the vehicle-rail subsystem are described by differential equations. In the slab-subgrade subsystem, a three-dimensional finite element model is established to obtain the Green functions of the system induced by a unit impulse excitation. Based on the derived Green functions, dynamic equations of the slab-subgrade subsystem are formulated by the Duhamel integral. The interaction between the two subsystems is transferred by the fastener forces, and the dynamic responses of the whole system are solved through explicit numerical methods. The proposed method is subsequently validated through a detailed numerical comparison with the result obtained by the finite element method. Finally, the method is applied to investigate the dynamic property of the subgrade system under high-speed train operation.

The Impacts of Pollution for New High-Speed Railways: the Case of Noise in Turkey

In recent years, high-speed train operations have been increasing, yet their environmental impact is still not well researched and understood. Evaluation of the impacts of Turkey’s new high-speed train lines from the perspectives of noise, vibration and socio-economic issues is important to secure sustainable development in the sector. National and international regulations are important to enable environmentally friendly railway systems to be secured. In this study, national and international regulations for the control of noise from conventional and high-speed train operations are reviewed and used to estimate distances which should not be exceeded for the Turkish high-speed train system. Calculated distances for EU and Turkish systems for noise threshold values of 87 dB (A) pass-by noise (LpAeq,Tp—measured 25 m distance from the centreline of the track and 3.5 m above the rail head), 65, 60 and 55 dB (A) (LpAeq, day; LpAeq, evening and LpAeq, night, the A-weighted average sound level for the specified time periods, at the most affected residential area, 4 ± 0.2 m above the ground) were 28, 160, 272 and 469 m from the centreline of the track, respectively. These threshold distances were defined as a buffer zone in a railway map of Turkey in ArcGIS v.10.2.1 and merged with the Turkey population map to determine the population numbers which would be subjected to exposure above the threshold limits. Calculations conducted for highly populated cities showed that 2325, 22,839 and 3184 people would be exposed to railway noise exceeding the EU 96/48/EC Directive threshold limit 87 dB (A) for Ankara, Istanbul and Izmir, respectively. When calculations were repeated for the Turkey regulation threshold limits 65, 60 and 55 dB (A), these numbers were 10,767, 19,298, 35,951 for Ankara; 125,033, 210,360, 357,041 for Istanbul and 17,340, 29,026, 49,318 for Izmir, respectively. The data indicate that some noise mitigation is required to protect human health in Turkey and potential mitigation strategies are discussed.

Hardness matching of rail/wheel steels for high-speed-train based on wear rate and rolling contact fatigue performance

Hardness matching between rail and wheel is important for the safe and economic operation of high speed train. In this work, various hardness of 39.5, 36.8, 33.4, 30.5, 28.1 HRC were achieved in the wheel steels tempered at 748, 773, 793, 813, 833 K, respectively. Then the twin-disc fatigue test under 1000 MPa of Hertzian contact stress, 1676 r min−1 of rotating speed (i.e., 300 km h−1) and 0.7% of creepage was conducted using these tempered wheel steels and U71MnK rail steel with the hardness of about 32 HRC. Thus various hardness ratio of Hr/Hw (Hr is the hardness of rail and Hw is the hardness of wheel) including 0.81, 0.89, 0.96, 1.07 and 1.17 were achieved. Finally, wear resistance and rolling contact fatigue performance of the wheels as the function of Hr/Hw were evaluated and the relevant failure mechanism was discussed basing on the worn morphology and mechanical properties. The results indicated that wear rate of wheels increased with Hr/Hw. Furthermore, the wheel/rail couple presented the longest fatigue lifespan of 150 000 cycles when Hr/Hw was 0.96. Thus it can be concluded that the optimal hardness ratio of Hr/Hw was 0.96 basing on the less wear rate and the longest fatigue lifespan of the wheel/rail couples under high speed of 300 km h−1 due to the reasonable strength, ductility, toughness and hardness of the wheel steel tempered at 793 K.

Optimization study of jinghu highspeed railway train operation diagram

This article is based on familiarization with the technical methods of the standardized highspeed train operation diagram. Investigated the existing problems of the train working diagram of highspeed train between Beijing and Shanghai. In the process of train operation diagram compilation,analyze the difficulties based on the normalized. The operating diagrams which optimized from the various processes have been prepared from organization. The optimization plan of the normalized train operation diagram on the Jinghu highspeed train was proposed as well.

Application of remote monitoring and management of high-speed rail transportation based on ZigBee sensor network

Operational safety is the prerequisite for high-speed railway to carry out transportation work, and with the increasing mileage of high-speed railway in China, higher requirements are put forward for monitoring the operation environment of high-speed trains. From the point of view of the whole road, the wireless sensor network technology is fully applied to the monitoring of high-speed train operation environment. Based on the actual requirement of the high-speed train operating environment monitoring, the overall structure and logic frame of the high-speed train operating environment monitoring system based on wireless sensor network are put forward. By establishing the node structure model algorithm, and taking natural disaster and foreign object intrusion detection as an application example, the natural disaster and foreign object intrusion detection system based on wireless sensor network are designed.

Research on influence of harmonic wear wheel on wheel/rail contact geometry of high-speed train

Harmonic wear is one of the common wear phenomena of high-speed train wheels. The change of wheel/rail rolling contact geometry leads to unstable characteristics of wheel/rail contact, which directly affects the quality and safety of high-speed train operation. Because wheelset lateral displacement directly affected the wheel/rail contact geometry, in this paper, the UM software was used to establish a high-speed train vehicle-track coupled dynamics simulation model of the CRH2 (China Railway High-speed 2) head car. Lateral displacement of harmonic wear wheel was calculated under different wear condition to analyze the influence of harmonic wear wheels on wheelset lateral displacement. Then according to macroscopic dimension change of the wheel profile from lateral and radial directions of high-speed train induced by harmonic wear wheels, wheel profiles under different wear condition were selected. And wheel/rail contact geometry under different harmonic wear stages was calculated to discuss the influence of harmonic wear wheel on wheel/rail contact geometry. The results show that harmonic order and wave depth of harmonic wear wheel have small influence on the lateral displacement of wheelset, but the influence of wave depth is greater than harmonic order. The average difference of lateral displacement between harmonic wear wheel and no harmonic wear wheel increases with the increase of wave depth and order. In a harmonic wave length, the maximum value of both equivalent conicity and contact angle appear in deepest wave depth. The greater the wave depth, the more obvious the fluctuations, and equivalent conicity changes are less obvious.

Arching mechanism of the slab joints in CRTSII slab track under high temperature conditions

China Railway Track System II slab track is widely applied to China high-speed railway. Under the high temperature conditions, it tends to produce different degrees of arch at the joints between prefabricated slabs, which will affect the track irregularity and safe operation of high-speed trains. In this paper, considering the buckling instability of track structure, the arching mechanism of the slab joints was investigated by establishing a 3D finite element model of the CRTSII slab track. Combined with the field investigation, the damage process of joint concrete and its effects on the arching instability were analyzed. The results show: 1) The construction of joint concrete is difficult to control on site, which leads to inferior quality compared to prefabricated slab. The worse quality of joint concrete corresponds to a smaller amplitude of temperature rise causing joints damage and a greater damage area. 2) When the amplitude of temperature rise of the slab is over 37 °C, various damage emerges in the narrow joint and the middle of wide joint, resulting in the eccentric compression. 3) The temperature gradient load will cause the propagation of interface gap between slab and CA mortar layer, which aggravates the arching instability of slab, especially when the height of gap exceeds 1.5 mm. This research is expected to provide guidance for the optimization design, maintenance and damage control of slab track.