最新刊期
卷 ， 期 4 ， 2022
- 摘要：In order to grasp the elastic deformation characteristics of levitation electromagnet and levitation bogie of high-speed maglev vehicle, a rigid-flexible coupling dynamic model of high-speed maglev vehicle considering the flexibility of levitation electromagnet and levitation bogie was established. The elastic deformation of levitation electromagnet and levitation bogie under the five kinds of levitation electromagnet bending stiffness and three kinds of plane curves ( radius is 650 m, 1 000 m and 4 000 m ) was simulated and analyzed. The results show that the deformation of the levitation electromagnet is the largest on the curve of radius at 1 000 m. When the bending stiffness of the levitation electromagnet decreases by 50% from the existing design value, the dynamic overall deformation amplitude of the first levitation electromagnet increases from 0.49 mm to 0.82 mm, which is larger than the rated suspension clearance of 10 mm, and the overall deformation amplitude of the second levitation electromagnet increases from 0.11 mm to 0.23 mm. With the increase of the bending stiffness of the levitation electromagnet, the dynamic deformation decreases approximately linearly. The levitation bogie twists along the track on the mitigation curve, and the torsion angle is the largest at the midpoint of the mitigation curve. The torsion angle of the first levitation bogie is always less than that of the second levitation bogie. Overall, the bending stiffness of the levitation electromagnet has little effect on the torsional deformation of the levitation bogie, and has a certain effect on the elastic deformation of the first levitation bogie bracket, and has little effect on the second levitation bogie bracket.关键词：maglev train;levitation bogie;electromagnet;curve negotiation;rigid-flexible coupled dynamics;elastic deformation;simulation
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发布时间：2024-08-02 - 摘要：Superconducting electrodynamic levitation represents one of the development trends of the maglev technology. Taking the superconducting electrodynamic levitation train running on the Yamanashi test line as the research object, this paper was aimed to further study the levitation characteristics of the superconducting electrodynamic levitation system. A three-dimensional transient simulation model of the single-side on-board magnet - zero-flux coil was established. Firstly, the accuracy of the model was verified according to the released test data, and then the effect of the superconducting magnet length on the levitation force of the train was studied with this model. Finally, the levitation force characteristics of the length-optimized superconducting magnet under different speeds, vertical displacements, and lateral displacements were analyzed, focusing on fluctuation of levitation force. The research results show that the simulation results are close to the released test data, with an error less than 10%, which verifies the accuracy of the simulation model. In addition, the length of the superconducting magnet has little effect on the lift/drag ratio of the train, and the mean value of the levitation force increases linearly with the increasing length of the superconducting magnet; when the coil length is 1 110 mm, the fluctuation amplitude and the fluctuation coefficient of the levitation force are the smallest. The higher the speed, the smaller the fluctuation coefficient of the levitation force; at 500 km/h, the vertical displacement and the lateral displacement within a certain range have little effect on the fluctuation coefficient of the levitation force. The conclusions of this paper provide a reference for the optimization of the dynamic performance of electrodynamic levitation trains.关键词：superconducting electrodynamic levitation;superconducting magnet;finite element analysis;electromagnetic simulation;levitation force;size optimization
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发布时间：2024-08-02 - 摘要：For the deformation of the wheel-axle structure and the contact of the axle-sliding bearing of variable gauge bogie for1 435 mm/1 520 mm with a speed of 400 km/h, the vertical load values of axle journals were calculated in accordance with the standard EN 13104; based on Hertz contact theory, the semi-axis lengths of wheel-rail contact elliptical spots were solved to determine the constraint area of the wheel; according to the characteristics of the wheel-axle structure, the contact relationship of axle-sliding bearing was analyzed. The finite element model of the wheel-axle structure was established to study the effects of the thickness of resin of sliding bearing, the fit clearance between the axle and sliding bearing and centrifugal force on the deformation of the wheel-axle structure, the contact pressure of axle-sliding bearing and the shear stress of resin layer. The results of the calculations show that compared with resin-free layer, the surface of the inner hole of the sliding bearing with resin, which can reduce the structural deformation and significantly decrease the contact pressure and edge effect of axle-sliding bearing. It has little effect on the deformation of the wheel-axle structure, the contact pressure of axle-sliding bearing, and shear stress of resin layer when the fit clearance between axle and sliding bearing within 0-0.3 mm. The speed of vehicle increases in the range of 0 to 400 km/h, which has little effect on the structural deformation, but the contact pressure of the axle-sliding bearing and the shear stress of the resin layer both show obvious nonlinear growth.关键词：variable gauge bogie;wheel-axle structure;axle-sliding bearing;structural deformation;shear stress;high-speed train;FEA
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发布时间：2024-08-02 - 摘要：Virtual rail train is a product of the integration of railway vehicles and buses. It uses the principle of photoelectricity or electromagnetism to identify the virtual track set on the road surface and drive along it. In order to make virtual rail train with 100% low-floor rate and meet actual operation requirements power, a running system of wheel hub motor drive and independent suspension structure was designed. In view of this newly designed running system structure, the dynamic envelope calculation method was used to check the rationality of the running system structure layout. The finite element model of suspension system was established by using the finite element analysis software ANSYS to analyze the static strength and fatigue strength of the main load-bearing parts such as kingpin, steering knuckle, upper and lower cross arms and their mounting pins. The dynamic calculation model of virtual track train was established by UM software, and the stability and comfort of virtual track train equipped with this running system were simulated and analyzed. The calculation and analysis results show that there is no interference between the parts of the running system and the utilization of structural space is reasonable; The maximum Von-Mises stress of the main load-bearing parts is less than the yield strength of the corresponding material under various static load conditions, and under the fatigue load condition, the material utilization rate of the main load-bearing parts is less than 1, that is, the static strength and fatigue strength of the suspension system meet the standard requirements; The stability and comfort indexes of the train increase with the increase of speed, but within the range of the maximum test speed (80 km/h), the stability indexes are less than 2.5, belonging to the excellent level, and the comfort index is less than 2.5, belonging to the comfort level. Therefore, the structure design of the virtual track train running system is reasonable, and the parameter setting meets the requirements of dynamic performance..关键词：virtual rail train;running system;structural design;dynamic envelope;strength;comfort;simulation
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发布时间：2024-08-02 - 摘要：As a ground transportation, the tram needs frequent speed regulation. Relying on mechanical braking when decelerating will cause excessive wear of the mechanical devices. Therefore, it is proposed to install a permanent magnet reduction device on the tram. In this paper, a permanent magnet deceleration device was designed without changing the original brake control system of the tram and its associated mechanism. The position of the magnetic pole of the permanent magnet was changed by the actuating mechanism to obtain different spatial magnetic fields, to achieve the purpose of obtaining different induced eddy currents and corresponding braking torques on the turntable, which achieved the conversion of braking and mitigation. Under the limited space of the tram, the structural size of the deceleration device and the braking torque of the deceleration target were derived. The mathematical model of the eddy current braking torque was established, and the influence of structural parameters on the braking torque was analyzed. The prototype was developed and the performance parameters were verified to meet the design requirements.关键词：train braking;tram;permanent magnet deceleration device;magnetic analysis
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发布时间：2024-08-02
Advanced Transport Equipment
- 摘要：With the emergence and application of new generation power semiconductor devices, power electronic traction transformer (PETT) for traction has gradually become a research hotspot in the industry, while the high-voltage cascaded rectifier is the core component of PETT. Based on the synchronous rotating coordinate system, an improved single-phase four-quadrant converter control strategy based on the theory of instantaneous power balance was proposed, which realized the rapid adjustment of the active and reactive parts of fundamental current; then through the absorbed power regulation of each cascaded power modules, the cascaded rectifier achieved voltage balance control; at last, a specific harmonic suppression method was proposed, the harmonic modulation wave command was superimposed on the fundamental wave and the modulation wave of the voltage balance control to formed a total voltage command to achieve combination control of the system. Experiments show that when the traction grid voltage drops by 20%, the response time is less than 20 ms; when the grid voltage is distorted, the grid side current is guaranteed to have no low-order harmonics such as 3, 5, and 7; meanwhile, when the load diversity is 20%, the control system can still maintain the balance of DC voltages.关键词：PETT;high-voltage cascaded rectifier;synchronous rotating coordinate system;instantaneous power balance;specific harmonic suppression
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发布时间：2024-08-02 - 摘要：Interactions between the Ethernet-based train communication network (ETCN) and the outside information environment are increasing rapidly, which means that ETCN is facing severe cyber security threats. There is no systematic and macroscopic qualitative analysis of the vulnerability of ETCN at home and abroad, therefore it is urgent to analyze its security vulnerability. Firstly, from the perspective of network protocols and network devices, a macroscopic qualitative analysis of the vulnerabilities of ETCN were carried out. Secondly, potential attacks against ETCN were analyzed through the subjects, routes, and behaviors of attacks. At last, an ETCN attack testbed was built to conduct experiments on several kinds of primary attacks. Experimental results indicate that the vulnerabilities exploited by these attacks exist in ETCN and are easy to be compromised.关键词：train communication network;industrial ethernet;network attack;security vulnerability analysis;cyber-physical system
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发布时间：2024-08-02 - 摘要：Aiming at the low efficiency of the manual infrared image processing and the low intelligence degree in the state diagnosis of traction power supply equipment, a two-layer network model based on Inception-V3 and Mask-RCNN was proposed in this paper. In this diagnosis method, the first step was to identify power equipment types through Inception-V3 network; on this basis, Mask-RCNN was used to realize automatic division of different equipment structural regions; according to the coordinates of the divided structural regions, the highest temperatures of different regions were extracted, the temperature characteristic quantities were constructed, and the equipment status was automatically diagnosed by invoking different criteria according to the type of equipment. The experimental results show that the overall mAP value of power equipment structural division by using the double-layer improved network model can reach 0.907 2, and the efficiency of equipment fault diagnosis can be improved by 95.41% compared with manual processing. The model featuring a high accuracy and good recognition effect, works independent of fault samples, which improves the efficiency of infrared image processing in equipment diagnosis and reduces the labor intensity.关键词：traction power supply equipment;deep learning;infrared detection;fault diagnosis
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发布时间：2024-08-02 - 摘要：In order to analyze the influence from traction power supply system harmonics of the electric multiple units (EMUs) on the power grid, a load simulation model was established, which can truly reflect the harmonic fluctuation of traction power supply system with EMU included. Based on the measured data, a fast generation method of EMUs probabilistic harmonic model was proposed and verified in this paper. With a direct traction power supply system built in MATLAB/Simulink, considering the nonlinear characteristics of transformer harmonic impedance, the law of influence from the number and location of EMUs and the short-circuit capacity of the power grid on the electric energy quality of the power grid was analyzed through simulation, and a quantitative formula was given accordingly. This formula can be used to rapidly evaluate the possible harmonics occurring when a traction power supply system is connected to the public grid, which provides a certain theoretical basis for the subsequent harmonic suppression.关键词：EMU;harmonic;probabilistic model;power quality;power grid;traction power supply system;simulation
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发布时间：2024-08-02
Electric Traction and Control
- 摘要：In view of the limited accuracy of the traction calculation method specified in the code for train traction calculation in solving the air braking process of 20 000 ton heavy haul combined trains, based on the existing air braking calculation model of traction gauge, an air braking process solution method suitable for long marshaling heavy haul combined trains was put forward. Firstly, by analyzing the limitations of the traction gauge model and based on the dynamic behavior of the air braking system, the air braking process of heavy haul train was described as idling stage, braking force establishment transient stage and braking force stability steady-state stage according to the time node. Secondly, considering the influence of historical handling behavior on the current air braking performance, the air braking performance correction function was introduced; considering the influence of train formation form on brake wave distribution and brake wave transmission, the brake shoe pressure distribution function of combined train was introduced. Then, based on the basic calculation method of traction gauge air braking force and considering the continuity of air braking force distribution in the whole braking process, a three-stage refined air braking force calculation model was summarized. Finally, based on the actual operation data of 20 000 ton heavy haul train, the model error evaluation function was defined, and the correctness and effectiveness of the refined model were demonstrated by comparing with the existing traction gauge model. The results show that the model has good adaptability under the conditions of single short ramp braking and long downhill cyclic braking of heavy haul train.关键词：heavy haul combined train;air brake;transient phase;steady state phase;mathematical model;simulation
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发布时间：2024-08-02 - 摘要：The mountainous rack railway system currently becomes a hot topic in urgent need of research and development, under the backdrop of the development status quo and the application demands for rail transit systems in China, and in order to respond to the call for integrated development of “tourism + traffic + poverty alleviation” in mountainous regions. This paper mainly comprised the introduction on the features, development history and key technologies of rack railways, analysis on the application environment, and comprehensive elaboration on the key technologies from the aspects of the standard system, vehicle dynamics, driving and braking, and so forth. The rack railway system was designed with a ruling gradient up to 120‰ generally and even 250‰ at the maximum, and a negotiable radius of curve of 50 m to the minimum extent in the main line. Boasting the strong adaptation to the topographic conditions of mountainous lands, the rack railway system will certainly become a mainstream choice for the construction of mountainous tourism railways in China.关键词：rail transit;rack railway;rack rail vehicle;key technology
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发布时间：2024-08-02 - 摘要：In the traditional design process of bogies, engineers always had to balance the conflict between the operational stability and curve negotiation performance for railway trains, which can be effectively solved by applying the wheelset active steering technology. This paper analyzed the characteristics of several types of active steering devices commonly used, and put forward a novel active steering device suitable for the bogies with the rocker type journal box positioning, which integrated two plunger cylinders in the rubber joint. When the train ran on a curve, such an active steering device could exert control over the plunger on one side to push the journal box to move in the longitudinal direction and relative to the frame, thus realizing the wheelset active steering. Finally, the proposed active steering device was proven with excellent performance according to the analysis results. The research results provide a technical idea for the engineering application of the wheelset active steering technology.关键词：railway vehicle;rocker type positioning;active steering;controllable rubber joint;fail-safe principle
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发布时间：2024-08-02 - 摘要：In order to study the dynamic performance of the tilting train based on the active air spring control technology, a nonlinear vertical model of the air spring and the system dynamics model of the tilting train were established, incorporating the connecting pipeline, the additional air chamber and the tilting valve. The co-simulation of multi-body dynamics software Simpack and numerical calculation software Simulink was applied to explore the dynamic performance of the tilting train running on a curve at a high speed. The influence from angle stiffness of the anti-roll torsion bar on train tilting under the active air spring control was analyzed. The suspension parameters such as the lateral stopper stiffness and lateral stiffness of the air spring were optimized to ensure the running stability of the train on curves. The results show that the active air spring control technology can reduce the unbalanced centrifugal acceleration experienced by passengers and increase the curve negotiation speed without changing the bogie structure and track conditions. The vertical stiffness of the air spring should be well matched with the anti-roll angle stiffness, and the anti-roll angle stiffness should be reduced as far as possible under the premise of meeting the flexibility coefficient, to reduce the tilting resistance and relieve the pressure fluctuation of the air spring. In consideration of the fact that the active air spring control technology causes swaying increase between the carbody and the bogie, resulting in the carbody collision with the lateral stopper, reasonable matching between the lateral stiffness of the air spring and the lateral stopper stiffness can effectively reduce the carbody swaying, avoid hunting instability of the train passing on a curve with a large deficient superelevation, and improve the curve negotiation performance of the train.关键词：tilting train;active control;air spring;dynamic performance;lateral stopper;high-speed EMU;high-speed train
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发布时间：2024-08-02 - 摘要：A finite element model of the double-deck EMU trains including the on-board traction converter was established, and the main low-order elastic modes of the car body were calculated and analyzed separately when the converter equipment adopted rigid suspension and elastic suspension. The results show that when the equipment adopts elastic suspension, the modal frequency of the car body is higher than the modal frequency of rigid suspension. A rigid-flexible coupling dynamics model of the double-deck EMU vehicle including the on-board traction converter was established to study the influence of the different hanging frequencies of the traction converter on Sperling index of the vehicle, and the transverse tension of the hanging point of the converter under different hanging frequencies was also analyzed. The results show that when the hanging frequency is 13 Hz, the lateral and the vertical Sperling index are low; with the increase of the hanging frequency, the transverse tension of the converter suspension increases. If the hanging frequency is lower than 13 Hz, the transverse tension of damping element of hanging point is lower than 400 N.关键词：high-speed train;EMU;on-board equipment;modal analysis;riding stability;FEA;track irregularity
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发布时间：2024-08-02 - 摘要：The structural analysis of rail transit converters installed under the vehicle often involves time-consuming computer simulations to evaluate the strength of the structure for safety requirements. For typical rail transit converters, each static strength analysis with four working conditions costs at least 1 hour, and each random vibration analysis with one axis costs more than 8 hours. As a result, for using traditional engineering optimization methods to optimize the converter structure, the optimization efficiency will be severely limited, since these methods need to invoke a large amount of simulations as function evaluations. In this paper, machine learning methods were considered to approximate the functional relationships between design variables and responses. Specifically, the Latin Hypercube Sampling method was used to generate the samples and build Kriging surrogate models (also known as Gaussian Processes). With the information provided by the Kriging models, the sensitivity analysis, design space exploration and global optimization processes can all be facilitated so that the designers can avoid low safety allowance and over-redundant designs while the design circle is also shortened. A complete technical route of Kriging-based analysis and optimization was provided in this paper, and the key steps (design of experiments, surrogate model, adaptive sampling, sensitivity analysis, design space exploration, global optimization, etc.) were described in detail. Finally, the proposed technical route has been verified the validity by the analysis and optimization of a traction converter lug structure.关键词：rail transit equipment;converter lug;structural optimization;Kriging surrogate model;machine learning;Gaussian processes;simulation
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发布时间：2024-08-02 - 摘要：Resilient wheels can effectively reduce the transmission of high frequency vibration and impact between wheel and rail, and reduce wheel/rail noise, so they are widely used in tramcars. However, in the process of application, it is found that there is relative rotational motion between the tyre and the wheel center, and the phenomenon of wheel sluggish movement is formed, which may affect the life of the wheel and the economy of operation, or even affect the safety of vehicle operation. In this paper, the performance of the rubber components of the resilient wheel, the anti-sluggish torque of the wheel and the difference of the vehicle vibration with or without wheel-rail lubrication were analyzed, and the vibration time and frequency diagram and the inherent frequency of the resilient wheel obtained by modal test were compared, which concluded that: the wheel sluggish movement of resilient wheels was caused by vehicle resonance when the vehicle passed through the small radius curve without lubrication between the wheel and the rail, the resonance energy caused the contact surface of the wheel center and the pressure ring and the resilient wheel rubber block to rotate and slip. In order to avoid the resonance, reasonable use of wheel-rail lubrication was proposed, and the resilient wheel sluggish movement was proved disappeared after application..关键词：resilient wheel;sluggish movement;tram;modal;vibration;lubrication;simulation
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发布时间：2024-08-02 - 摘要：In order to study the influence of bidirectional ratio of hydraulic shock absorber in locomotive suspension system on locomotive dynamic performance, a vehicle dynamic model with 90 degrees of freedom was established by using Simpack software, which consisted of body, frame, wheelset etc. The nonlinear damping characteristics of shock absorber were embedded. Under random excitation of AAR 5 track spectrum, the locomotive dynamic performance corresponding to the damping model with two-way ratio of shock absorber greater than, equal to and less than 1 was simulated and analyzed respectively. The results show that: When the bidirectional ratio of primary vertical shock absorbers is 1, the vertical Sperling stability index of the locomotive under linear working condition is 3.08, and the maximum acceleration power spectral density is 0.11 m2/s3, both of which are smaller than the damping model with bidirectional ratio not 1, and the vibration transmission to the car body is more effectively attenuated. The vertical dynamic load coefficients of the primary and secondary suspension systems are minimum when the bidirectional ratio of the shock absorber is equal to 1, but they are not minimum when the vehicle speed is greater than 100 km/h. For the damping model with bidirectional ratio of 1, the anti-derailment coefficient of the locomotive and the vertical dynamic load coefficient of the secondary suspension device under curving conditions are better than that with bidirectional ratio greater than 1 or less than 1, but the vertical dynamic load coefficient of the primary suspension device is the largest. When the bidirectional ratio of the secondary transverse shock absorber is 1, the maximum nonlinear critical speed of the locomotive reaches 263 km/h, which is higher than that when the bidirectional ratio is greater than or less than 1. The research can provide some reference for the design of locomotive suspension system.关键词：six-axis locomotive;dynamics;shock absorber;damping;bidirectional ratio;track irregularity;electric locomotive
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发布时间：2024-08-02 - 摘要：Stress factor is an important parameter defined in EN 15085-3 standard. In order to obtain reliable stress factor calculation results, according to the fatigue load cases provided in EN 13749, the stress factors of key joints in typical frame were calculated and compared based on Goodman-Smith fatigue limit line diagram and master S-N curve method respectively. For the fatigue limit method, taking a pipe joint as an example, according to the comparison of different stress extraction methods, it was proved that the stress at the weld toe obtained by interpolation linear extrapolation was more conservative. For the master S-N curve method, the equivalent calculation formula of stress factor using cumulative damage was deduced. The calculation results of the stress factor of the welded joints of the actual frame showed that due to the different calculation methods of the stress factor and the basic data of anti-fatigue design used under static and dynamic load cases, the maximum value and position of the stress factor of the same weld in the structure may be quite different. Therefore, when applying EN 15085-3 standard, the calculation of stress factor should refer to the calculation results of two load cases at the same time, so as to more reasonably determine the weld quality and inspection class. In addition, the analysis showed that the stress factor calculation based on S-N curve method could also consider the fatigue damage contribution of multiple load cases and reflect the influence of the change of load cycles and the improvement effect of weld toe. Therefore, the calculation result is more reliable and the application is more flexible.关键词：welded joint;stress factor;Goodman-Smith fatigue limit line diagram;master S-N curve method;cumulative damage;bogie frame
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发布时间：2024-08-02
Railway Rolling Stock
- 摘要：In order to explore the wear mechanism of pantograph carbon slide surface, taking the pantograph copper to impregnate carbon slide material before and after the wear of a domestic subway line as the object, the surface microstructure and chemical composition of the carbon slide were tested and analyzed by electron microscope, laser confocal microscopy, scanning electron microscope and energy dispersive spectrometer. The results showed that the surface color of carbon slide changed obviously after wear, and the surface morphology changed from machining gully to wear scar, few cracks and arc ablation holes; the results of SEM and EDS showed that the distribution of C and Cu phases on the surface of unwearied pantograph carbon slide was relatively clear, while the distribution of C and Cu elements on the surface after wear was relatively uniform and there was no obvious boundary, indicating that the oxide film was formed during the wear process; arc ablation gathered in the relatively concentrated area of Cu distribution. The main wear forms of the surface were arc ablation, mechanical wear, abrasive wear and material transfer. Among them, arc ablation had the greatest impact on wear, inducing arc ablation pits, the material surface presents a typical rough and rugged morphology, and the friction condition deteriorated significantly, which aggravated the vibration of pantograph and catenary, further affected the friction surface, and led to the increase of temperature rise of contact pair and arc ablation. The resulting high temperature induced material transfer. Under the combined action of various wear forms, the surface cracks of the pantograph carbon slide plate continuously initiated and expanded, and finally, the surface material fell off, resulting in the surface wear of carbon slide plate.关键词：metro train;copper impregnate carbon slide;wear mechanism;micro-analysis;arc ablation
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发布时间：2024-08-02 - 摘要：When the locomotive is running on an electrified railway, it is necessary to ensure the continuous and reliable power supply of the catenary system. The contact wire wear will affect the current-receiving quality, and it needs to be monitored in real time. For the low accuracy and poor robustness of the current contact wire wear detection system, a contact wire wear detection algorithm based on Hough transform was presented. Firstly, the profile data collected by the structured light device was preprocessed with mean shift algorithm and cubic spline interpolation; secondly, the center of the contact wire was determined according to Hough transform; finally, the wear based on the geometric characteristics of contact wire was calculated . Experimental results show that the method has better accuracy and robustness compared with the classical least squares fitting, and can meet the real-time detection requirements.关键词：contact wire;catenary;wear detection;laser triangulation;mean shift;Hough transform
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发布时间：2024-08-02 - 摘要：To simplify the computing process for the structural vibration modal properties of railway catenary based on absolute nodal coordinates, this paper proposed a fast computational method based on the advanced flexible multibody dynamics. By establishing an equivalent spring model to simplify the constraint conditions, the complicated constrained dynamics of catenary was transformed to the classical structural vibration solution, and the quality matrix and rigidity matrix were generated for the simplified system. The structural vibration modal of the flexible catenary was computed by using the MATLAB characteristic value computation function Eig. The proposed method was first applied to vibration of the classical simply supported beam. According to comparison between the computed results and corresponding theoretical solutions, the proposed method could accurately compute modal frequencies and vibration shapes of the simply supported beam. Moreover, the effect of the equivalent spring stiffness coefficient on the calculation results was analyzed. The results show the characteristic modal frequency can be computed accurately in the modal analysis of two kinds of catenaries. The proposal method provides a theoretical basis for further study on pantograph-catenary interaction dynamics.关键词：high-speed railway;catenary;finite element method;absolute nodal coordinate;dynamic model;modal analysis
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发布时间：2024-08-02 - 摘要：The pantograph arc has become an important factor restricting the further development of high-speed trains. Therefore, in-depth research on the characteristics of pantograph arc is of great significance for further analyzing the damage characteristics of pantograph-catenary system and exploring the control method of pantograph arc. Combined with the actual wear of the contact wire and the pantograph strip, a two-dimensional dynamic analysis model of the pantograph arc under cross wind was established, the change rule of dynamic characteristics of the pantograph arc under the action of wind was studied. The results show that under the action of external wind, the arc column bends, pulls up, and is accompanied by the phenomenon of arc root jumping; the pantograph strip wears an obvious low wind speed zone. When the arc root is located in this low wind speed zone, the arc root displacement is slow and the arc heat accumulates, which will further aggravate the damage of the pantograph strip wear area; there is a low wind speed area on the right arc surface of the normal contact wire, where the arc root moves slowly, and the heat accumulates, causing damage to the contact wire; when there is wear on the contact wire, that is, the curvature of the bottom is reduced, the arc root of the surface moves faster. The wear of the contact wire and the surface of the pantograph strip will affect the flow field distribution in the arc area, and ultimately lead to differences in the arc root displacement distance and movement speed.关键词：characteristics of pantograph arc;MHD model;arc root displacement;simulation;high-speed train;catenary
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发布时间：2024-08-02
Railway Electrification
- 摘要：To ensure the operational safety of the autonomous-rail rapid transit (ART) trams on the structured roads, it is necessary to improve the efficiency and robustness of obstacle detection and tracking under different road conditions. This paper proposed a multi-target detection and tracking approach based on the fusion of LiDAR and millimeter-wave radar. Firstly, a millimeter-wave radar and LiDAR are used to perceive by single sensor, and the sensing results were merged by using a multi-source fusion algorithm, to generate more accurate detection results. Based on the false alarm filtering algorithm, the problem of false alarm probably caused by the millimeter wave radar was solved. The approach was based on the point cloud range image, and the gradient and distance characteristics to solve the problem of clustering obstacles in changing scenes. The cost function was derived from the characteristics of the segmented point clouds, which improves the robustness of the shape estimation algorithm. The multi-target tracking based on the track information raised the stability of target tracking. To overcome the challenge of heterogeneous sensor fusion, a multi-source sensor asynchronous fusion strategy was applied, which improved the target detection and tracking capabilities on the structured roads. The proposed approach was verified on the real ART trams based on the ROS framework. The test results demonstrate the stability, accuracy and reliability of the proposed approach.关键词：autonomous-rail rapid transit (ART) tram;segmentation clustering;shape estimation;interactive multi-model;multi-source information fusion
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发布时间：2024-08-02 - 摘要：The mechanical load is the only factor of influence considered in the traditional bearing lifetime prediction algorithm. However, for the traction motor of the electric multiple units (EMUs) in actual working conditions, its bearing is also subject to the additional electromagnetic load derived from the additional radial electromagnetic force acting on its rotor, which is under effect of bearing clearance. In this paper, the calculation method of bearing lifetime for the EMU traction motor based on the L-P theory and considering the electromagnetic load was expounded. In order to reveal the actual bearing clearance for the EMU traction motor, test was conducted in the real EMU scene, and the test results were statistically analyzed. Based on the measured bearing clearance of the EMU traction motor, the radial electromagnetic force probably acting on the traction motor bearing was calculated. Considering the influence from the electromagnetic force, the lifetime of the corresponding traction motor bearing was predicted and analyzed. The results show that any change in bearing clearance of the EMU traction motor has a considerable influence on the bearing lifetime of the traction motor. The test and lifetime analysis results of bearing clearance for the EMU traction motor provide guidance for the maintenance of EMU traction motor bearings.关键词：EMU;EMU traction motor;bearing clearance;eccentric magnetic pull;bearing lifetime;high-speed train
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发布时间：2024-08-02 - 摘要：To deal with the looseness of fasteners on the conductor rails of the medium and low speed maglev railways, a detection algorithm based on deep convolutional networks was proposed for loose detection of two kinds of fasteners, i.e. the base mounting bolt and the connecting plate screw. The first step was to locate the fastener area on the conductor rail for the sake of eliminating background interference; the second was to analyze any change of the fastener position for looseness detection. This algorithm was executed and verified through deep convolutional networks. Firstly, the areas of these two kinds of fasteners were located through YOLO V2 network; secondly, segmentation was conducted at the edge of the connecting plate, the insulator, the bolt and the screw, and the head of the connecting plate screw through the Mask R-CNN network simultaneously; finally, looseness of fasteners was detected by judging whether the position of any segmented part was changed. The proposed defect detection algorithm was tested using the data of the medium and low speed maglev system in Changsha, which revealed a looseness detection accuracy of over 90% for both the base mounting bolts and the connecting plate screws, and a recall rate of over 94%. The test results show that the method presented in this paper can accurately identify the loosened fasteners on the conductor rails of the medium and low speed maglev railways.关键词：conductor rail of medium and low speed maglev railways;fastener looseness;YOLO V2 network;Mask R-CNN network;Radon transform
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发布时间：2024-08-02 - 摘要：Aiming at the difficulty in extracting early faults of high-speed train motor bearings under the background of strong noise, an optimized VMD algorithm was proposed. Firstly, the vibration signal spectrum trend was obtained according to the spectrum trend estimation algorithm, thereby the resonance frequency band and the number of decomposition layers were determined; then, according to the boundary and bandwidth of each frequency band, the initial matrix of the penalty factor was obtained according to the value formula; finally the known parameters were substituted into the VMD algorithm to realize the decomposition of the signals. Verification by simulation signals and experimental signals shows that the method can more accurately identify the resonance frequency band under the condition of low signal-to-noise ratio, and accurately decompose the signal, which improves the accuracy and adaptability of the VMD algorithm.关键词：high-speed train;motor bearing;variational modal decomposition;frequency spectrum trend;fault diagnosis
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发布时间：2024-08-02
Detection Technology
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