To address the heavy computational burden and the complex vehicle-tube coupled vibration characteristics in modeling ultra-long tube dynamics for ultra-high-speed evacuated-tube maglev systems, this paper proposes a vehicle-tube coupled dynamical modeling method based on an Arbitrary Lagrangian-Eulerian (ALE) moving-region method (MRM). A three-dimensional tube dynamical model was established using Donnell-Mushtari thin shell theory; and a maglev vehicle dynamical model was developed based on the Newton-Euler method. A localized moving-region technique was introduced to efficiently compute dynamic responses of ultra-long evacuated tubes. Subsequent analyses investigated tube modal characteristics, localized vibration behavior under moving loads, and vehicle-tube coupled dynamic responses. Analysis results indicate that the low-order modal frequencies of tubes are significantly affected by their wall thickness, whereas the influence of internal pressure is relatively limited. Vibrations induced by moving loads are mainly concentrated near the load region. Moreover, the proposed moving-region method effectively reduces computational workloads for ultra-long tube dynamical modeling while accurately capturing the vehicle-tube coupled dynamic characteristics of ultra-high-speed evacuated-tube maglev systems.

High-temperature superconducting (HTS) magnetic levitation (maglev) offers a promising solution for urban and high-speed transport due to its self-stabilizing levitation and negligible magnetic drag. This paper introduces a novel V-shaped permanent magnet guideway (PMG) that achieves stronger magnetic-flux concentration than conventional flat PMGs, enabling reduced rare-earth magnet usage while enhancing both lift and lateral guidance performance. A validated finite element model is used to characterize the electromagnetic forces, which are then incorporated into a dynamic model of an HTS maglev vehicle, including a carbody, five bogies, ten air springs, and sixty cryostat-mounted HTS bulk modules. Dynamic simulations across speeds of 60-160 km/h show enhanced levitation efficiency, improved lateral stability, and acceptable ride comfort and vibration. These results demonstrate the feasibility of the V-shaped PMG concept and provide both theoretical guidance and engineering evidence for its application in future HTS pinning maglev transportation systems.

To address the attenuation of levitation force between the electromagnets and rails in maglev vehicles caused by high-speed operation, this study first analyzes the generation mechanism of eddy current effects (ECEs) based on electromagnetic field theory. A high-precision surrogate model for air-gap magnetic field calculation is established, incorporating the actual topological structure of the levitation electromagnets. Building on this foundation, an analytical electromagnetic force model accounting for ECE in both rails and electromagnets is developed. This model enables efficient parametric analysis of eddy current influences and is directly applicable to inverse problems in electromagnet topology optimization. To address the challenges posed by ECE on the engineering application of speed increase in medium- and low-speed maglev vehicles, this article analyzes the limitations of existing end-mounted levitation electromagnet structures. Based on the current balance optimization principle between front and rear suspension points, a nondominated solution set for structural optimization parameters is derived, aiming to mitigate uneven load distribution and compensate for ECE. Dynamic simulation results demonstrate that the optimized electromagnet structure effectively compensates for ECE while simultaneously enhancing track compatibility at levitation points. Experimental results indicate that at 140 km/h, the currents at both front and rear levitation points of the end-mounted electromagnets reach a balanced state, remaining below the rated value of 35 A. The outcomes of this study provide theoretical guidance for optimizing levitation systems in medium- and low-speed maglev vehicles at higher speed levels.

This paper investigates the nonlinear dynamics of the High-Temperature Superconducting (HTS) pinning magnetic levitation (MAGLEV) transit system under development at the University of L'Aquila. Due to its inherently weak damping characteristics, the MAGLEV system is particularly susceptible to external disturbances, such as mechanical or magnetic irregularities along the guideway. To analytically characterize its complex nonlinear dynamics, a simplified nonlinear single-degree-of-freedom model is developed, and the Multiple Scales Method (MSM) is employed as a solution technique. This approach enables the evaluation of how key design parameters influence the system's dynamic response. The analysis highlights the emergence of both primary and secondary resonances, which arise depending on system parameters and the nonlinear nature of the levitation force, potentially impacting not only performance but also stability. Finally, the analytical findings are validated against benchmark solutions obtained through direct numerical integration of the system's nonlinear equation of motion.

For high-speed operation of the high-temperature superconducting pinning (HTSP) maglev, adopting a coreless permanent magnet linear synchronous motor as the propulsion system ensures sufficient thrust while maintaining low normal force, thereby reducing the additional load imposed on the levitation system. In this study, based on the linear motor adopted in the HTSP maglev high-speed engineering prototype vehicle and test line, a three-dimensional finite element (FE) model is established to analyze the characteristics of the air-gap magnetic field distribution. The electromagnetic force of coreless and iron-core designs is compared. Subsequently, a two-dimensional analytical model is developed and further refined by incorporating the lateral end effect. Based on the three-dimensional magnetic field distribution obtained from the FE analysis, the analytical model is extended to a quasi-three-dimensional model. By comparing the analytical and FE models, the validity of the proposed analytical model is verified. On this basis, the influence of the air-gap length and the amplitude of the stator current on the electromagnetic force is investigated. The proposed analytical model is highly efficient in electromagnetic force calculation, providing a foundation for electromechanical coupling dynamics simulation of the levitation and propulsion systems in HTSP maglev.

Abstract Superconductivity was discovered more than a century ago, and it has achieved full commercialization for MRI and NMR applications. Superconducting technology has got on spotlight recent years for transportation, power network, and fusion energy, due to the significant advantages offered against its counterpart technologies, including lighter weight, compacter size, lower losses, higher efficiency, and higher power density. Therefore, many superconducting applications are moving towards higher technology readiness levels, with a fast pace. The accelerated research around superconducting applications for modern transportation is due to unique features of this technology towards decarbonisation via electrified systems. Meeting the Net Zero targets to decelerate global warming issue is the main driver of implementing the superconducting technology for aerospace, marine, and railway transport. However, many challenges still remain to be addressed for superconducting devices and applications, which will in turn pave the way for the commercialization of superconducting technology. In this article, a roadmap on electrification of transportation systems for aerospace, marine, and railway application is presented, covering challenges and solutions in design analysis, modelling, monitoring, and operation. A series of short articles are presented to outline the potential applications and solutions. These potential futuristic routes and their materials/technologies are considered/suggested for a 10-20 years time-frame.

The integration of linear motor and maglev technology enables contactless vehicle operation, laying the foundation for the speedup of rail transit. The high-temperature superconducting pinning (HTSP) maglev system is a passive levitation system, and its high-speed operation imposes explicit performance requirements on the traction system: a relatively large thrust to ensure high-speed traction capacity, a low normal force to avoid additional loads on the passive levitation system, and low thrust ripple to guarantee stable system operation. The ironless permanent magnet synchronous linear motor (PMSLM) meets all these demands, making it an ideal traction solution for HTSP high-speed maglev engineering. Focusing on the engineering application of HTSP maglev transportation, this paper takes the world's first HTSP high-speed maglev engineering prototype's ironless PMSLM as the research object, and investigates its electromagnetic characteristics based on actual prototype parameters. A finite element method model (FEM) is established to calculate the air-gap magnetic field and electromagnetic force, and a prototype test platform is built for experimental verification. Simulation and experimental results are in good agreement, verifying that the finite element model is reliable and accurate, and that the motor performance satisfies the system design requirements. Based on the validated model, the variation laws of electromagnetic parameters and the effects of key factors on electromagnetic force are clarified. The research results provide support for the collaborative design of traction-levitation-track systems and further promote the engineering application of HTSP maglev technology.

The electrodynamic suspension (EDS) system with cross-connected null-flux coil (NFC) configurations shows great potential for high-speed Maglev trains and electromagnetic launch systems. However, existing test platforms cannot experimentally simulate cross-connected NFC tracks. In this article, we propose a novel experimental approach to investigate the influence of crossconnection cables on dynamic performance in a laboratory environment. Firstly, a new rotating double-disk experimental EDS device equipped with cross-connected NFCs is introduced, with its structure, functions, and experimental procedures described in detail. Secondly, an efficient numerical model of the NFC-type EDS system, capable of accommodating general magnet arrays and arbitrary magnetization angles, is developed to support the electrical parameter design of the NFCs. Thirdly, comparisons of transient electromagnetic forces between numerical simulations (for both linear and rotary motion) and rotational experimental measurements demonstrate a high degree of consistency, validating the effectiveness of the proposed test platform. Finally, the transient performance of the EDS system with and without cross-connection cables is experimentally evaluated and compared. The results indicate that the cross-connected NFC configuration enhances the guidance force by 250% without compromising suspension performance. This experimental method, presented here for the first time, enables laboratory simulation of the dynamic behavior of cross-connected EDS systems and demonstrates considerable scalability. Moreover, the platform significantly enhances the capabilities of EDS testing by allowing flexible simulation of various coil and magnet configurations. As such, it provides an important reference framework for the design and experimental investigation of advanced EDS systems.

The limited intrinsic damping characteristics of the high-temperature superconducting (HTS) pinning maglev system pose challenges to effective vehicle vibration reduction under external disturbances such as permanent magnetic guideway (PMG) irregularities. This paper incorporates a magnetorheological damper (MRD) into the secondary suspension of HTS pinning maglev vehicles for semi-active vibration control. First, an MRD dynamic model considering the influence of current is presented, and a vehicle dynamic model developed based on an existing HTS pinning maglev test line and HTS-PMG relationship obtained from experiments. Subsequently, a semi-active vibration reduction co-simulation model is constructed using the skyhook (SH) linear continuous control strategy to evaluate the vertical and lateral dynamic performance of the car body under different operating speeds influenced by PMG irregularities. The results indicate that the semi-active damping strategy based on MRD ensures safe operation while effectively reducing carbody vibration, achieving over 50% vibration reduction rate at higher speeds, demonstrating its clear potential for improving the dynamic performance of HTS pinning maglev vehicles in practical engineering.

High-temperature superconducting (HTS) maglev trains represent the future of high-speed transport. Permanent magnet guideway (PMG) irregularities significantly affect vehicle performance, so accurately measuring and characterizing them is crucial for safe and reliable maglev train operations. This paper proposes two novel integrated measurement methods—static and dynamic—based on the world’s first HTS high-speed maglev test line. The static method combines a total station with custom-designed detection equipment to measure geometric and magnetic irregularities separately and characterize them uniformly through spatial transformation. The dynamic method involves utilizing the interaction between a scaled HTS maglev vehicle and the PMG, establishing a transfer function model to derive the PMG excitation characteristics from the dynamic response signals. Results show that the two methods, though differing slightly in power spectral density (PSD) amplitudes and signal sensitivities across frequency ranges, share the same overall trend and can capture key features complementarily. The static method excels in long-wave signal acquisition, serving long-line PMG acceptance and maintenance, defect detection, and model calibration by providing precise geometric and magnetic data. Conversely, the dynamic method is adept at train-operation monitoring, supporting vehicle-PMG coupling dynamics research and design optimization through swift short-wave signal collection. The combination of the two methods provides new methodologies and technical support for analyzing PMG irregularities, offering a reference for building a multi-dimensional measurement and analysis system for PMG.

Abstract Practical superconductivity applications offer significant advantages in energy efficiency and have considerable strategic importance. Owing to their zero-resistance property, superconductors offer great potential for railway transportation power equipment, such as superconducting cables and traction transformers. By exploiting the nonlinear current–temperature characteristics of superconductors, superconducting fault current limiters can be developed. Compared with conventional equipment, superconducting power devices enable low-loss, high-capacity power transmission and compact system integration. Moreover, superconducting devices, such as superconducting motors, superconducting bearings, and superconducting magnetic energy storage systems, offer high power density and low losses. The ability of superconducting magnets to carry large currents and generate high magnetic fields also makes them attractive for maglev transportation. Superconducting maglevs can levitate above the guideway without friction, which is conducive to higher speeds. Superconducting maglev systems can be broadly classified into low-temperature superconducting electrodynamic suspension (LTS EDS), high-temperature superconducting EDS (HTS EDS), and HTS pinning (HTSP) maglev systems. LTS EDS in Japan has achieved speeds of up to 603 km h −1 . HTSP maglevs also have the potential for high-speed operation and can be further combined with a vacuum tube to achieve higher speeds. The first high-speed HTSP maglev engineering prototype was developed and demonstrated in Chengdu, China, in 2021. However, the HTSP maglev systems face a series of challenges for engineering operation. On the other hand, insulation technology for superconducting power equipment and the instability of the rotor in superconducting electrical machines are challenges that also need to be overcome for their applications in railway systems. This paper also summarizes work conducted at Southwest Jiaotong University to address these challenges and develop practical implementations. It is believed that continued research and development will enable superconductors to play an important role in future railway systems. This development will help boost speed, reliability, and energy efficiency.

Superconducting electrodynamic suspension (EDS) trains promise very high-speed transport, yet electromechanical coupling can induce vibrations because of low or even negative damping, aggravated by track irregularities and high-frequency harmonics from discrete levitation and guidance coils (LGCs). An electromechanical coupling framework is developed together with an electromagnetic shunt damper (EMSD) for vibration suppression. An EDS train model integrates dynamic circuit representations of LGCs and damping coils with vehicle motion equations. The electromagnetic force module is validated against finite element simulations and experiments. A speed-based stepping window algorithm enables long-track simulation with reduced computational burden for mutual inductance and circuit matrices. Using fixed point theory, geometric and electrical parameters of the electromagnetic damper (EMD) and EMSD are optimized, and parameter sensitivity analysis examines how deviations in electromagnetic quantities affect attenuation across frequency bands. Simulations of suspension bogie system under random track irregularities show clear suppression by both an EMD and the EMSD; relative to EMD, EMSD reduces lateral acceleration RMS by 27.3% and vertical acceleration RMS by 17.5%. For a full train system at 600 km/h, EMSD reduces lateral acceleration RMS by 28.9% to 38.0% and vertical acceleration RMS by 2.4% to 7.4%, and lowers the vehicle body Sperling ride comfort index. By aligning electromagnetic and mechanical resonances, the optimized EMSD provides strong damping, most of all in the lateral direction. The framework offers a practical and scalable route to improve the dynamic stability of superconducting EDS trains, and future work will explore adaptive parameter tuning and intelligent control to coordinate damping across multiple vibration modes.

The rapid development of metro systems necessitates a thorough understanding of vehicle-track dynamics, where frictional heat at the wheel-rail interface induced by frequent acceleration, braking, and curving plays a critical yet not fully explored role. This study develops a three-dimensional (3D) finite element model for wheel-rail contact and a coupled vehicle-track dynamics model. Investigations are conducted into longitudinal friction forces at varying slip ratios (ξ) and the system’s dynamic behavior under different track irregularity spectra. The results reveal that the contact area measures 164 mm2 with a maximum contact stress of 1340 MPa. The temperature peaks at the center of contact area and increases with wheel slip ratio, achieving 1498°C on wheel and 602°C on rail under full sliding (ξ = 1). The longitudinal friction force evolves through three distinct phases with increasing slip ratio: linear growth (ξ ≤ 0.2), nonlinear transition (0.2 ≤ ξ ≤ 0.4), and saturated linear growth (ξ ≥ 0.4), attaining a maximum value of 24.6 kN at full slip. Furthermore, frictional heat significantly amplifies lateral force and derailment coefficient while having negligible effects on wheel-rail vertical force, vertical/lateral accelerations of vehicle body, and wheel load reduction rate. This research provides valuable insights for assessing operational safety in metro systems, highlighting the critical influence of thermomechanical effects on lateral dynamics.

High-temperature superconducting (HTS) maglev systems provide inherently stable, non-contact levitation and low energy consumption, making them attractive for high-speed transportation applications. However, the nonlinear dependence of levitation and guidance forces with lateral and vertical displacements leads to pronounced lateral-vertical coupling effects. These coupled vibrations, especially under external perturbations, can activate a broad range of resonant frequencies, thereby potentially affecting ride stability and operational safety. In this study, the nonlinear lateral-vertical coupled vibration responses of an HTS maglev system are investigated through integrated theoretical analysis, numerical simulations, and experimental validation. A coupled levitation/guidance force model is established via numerical simulations, quasi-static measurements, and dynamic experiments. The multiscale method is applied to derive analytical solutions for the coupled dynamics, under free vibration, lateral primary resonance, and forced vibration at critical frequencies. Theoretical analysis and numerical simulations reveal that lateral disturbances not only induce significant vertical responses but also excite a rich spectrum of resonant modes, including sum and difference frequencies between the lateral and vertical natural frequencies. These phenomena are confirmed by dedicated forced vibration experiments over a wide frequency range. Comparisons demonstrate strong agreement between theoretical predictions, simulations, and experimental data. Importantly, the study identifies specific frequency regions where the external excitation matches the sum or difference of the system's natural frequencies, which are critical for system stability and result in substantial amplification of coupled vibration amplitudes. The combined theoretical and experimental framework based on the multiscale method enables accurate prediction of the nonlinear lateral-vertical coupled dynamics in HTS maglev systems and clearly identifies the critical frequency regions that need to be avoided in design and operation. These findings are of great significance for ensuring the stability and safety of HTS maglev systems at high speeds and are essential for maintaining overall system reliability.

The suspension bogie is crucial for the high-temperature superconducting (HTS) maglev train, providing support, levitation, guidance, traction, braking, and shock absorption. This article developed a scaled HTS maglev vehicle with full functions based on the train's suspension bogie. Experiments were conducted on a short-distance test line to measure the dynamic response of the vehicle at speeds of 5, 6, and 7 m/s. A coupled model of the HTS vehicle-bridge system, accounting for track irregularities, was constructed and validated against experimental data. The model was then used to explore the dynamic response of the system under various conditions, identifying key factors affecting the safety and stability of the vehicle. This study combines experimental and numerical analyses and found that the vehicle's primary vibration frequency aligns with a single HTS levitator (a heat-insulation device equipped with liquid nitrogen and HTS bulks) under an identical levitation-load ratio. This correspondence confirms the identified frequencies as the natural frequencies of the maglev system. The numerical simulation analysis of the validated model reveals that the redundant HTS levitator configuration on maglev trains substantially optimizes dynamic performance, improving system safety and adaptability to load variations. As speed increases, the scaled vehicle's motion and the HTS levitator's vibration amplitudes rise, with a levitation gap of less than 8 mm at 180 km/h. The track beam's mid-span vertical vibration demonstrates velocity-robust dynamic responses. The vehicle exhibits superior dynamic response on small-span track beams. These findings provide valuable insights for future HTS maglev train dynamic research and structural design.

As a promising transportation solution, the high-temperature superconducting (HTS) maglev system is gaining attention in magnetic levitation technology due to its inherent passive self-stability. To align with this characteristic, this paper proposes a compact propulsion sys-tem featuring a linear synchronous motor (LSM) with an electromagnetic Halbach (EH) array. In this configuration, the air gap magnetic field is excited by the EH array with a triangular winding pattern. First, the magnetic field distribution of the EH array is characterized via analytical and finite element (FEM) modeling, and the single-side magnetic field perfor-mance is validated. Subsequently, the electromagnetic design of the EH-LSM is developed based on the novel HTS maglev suspension frame of the University of L'Aquila model 4 (UAQ4) Italian maglev train. The electromagnetic force characteristics are analyzed using analytical calculation and FEM simulation. The thrust error is controlled within 2.53%, meeting the requirements of the preset operating condition, while the normal force remains at a low level, approaching zero. Meanwhile, the electromagnetic force characteristics can be regulated by adjusting the current phase. Next, parametric analysis of the EH-LSM is per-formed to obtain the evolution characteristics of the magnetic field and thrust under different secondary structure dimensions and current inputs. The results indicate that the EH-LSM performs propulsion and holds promise as a compact and flexible driving solution in the HTS maglev system.

High-temperature superconducting (HTS) maglev technology offers significant potential for high-speed transportation due to its zero magnetic resistance. However, the inherent low damping characteristics of HTS maglev systems make them highly vulnerable to external disturbances, leading to reduced system stability, passenger discomfort, and thermal instability of superconducting magnets. Therefore, it is essential to simultaneously address vibrations in both the vehicle body and the suspension frame. To address this challenge, an electromagnetic damper is introduced between the vehicle body and the suspension frame, along with a skyhook-groundhook control strategy to collaboratively regulate vibrations of both components. The parameters of control algorithm are optimized using the entropy weight method, focusing on multiple dynamic performance indicators. Simulation results indicate that the proposed approach significantly reduces vibrations in the suspension frame and vehicle body simultaneously compared to traditional skyhook-only or groundhook-only control strategies. Consequently, the stability and ride quality of HTS maglev systems are enhanced, making them more suitable for high-speed transportation applications.

[Objective]Super-high-speed evacuated tube maglev transportation integrates the frictionless operation of maglev trains with the low air resistance of vacuum tubes,providing a transformative solution for the future of high-speed rail transit systems.This study aims to develop a comprehensive construction management model suitable for major science and technology infrastructure projects,balancing research flexibility and engineering rigor.The multimode coupled rail transit dynamic simulation test platform at Southwest Jiaotong University is selected as a systematic case study.[Methods]This research systematically reviews and analyzes the core technical and management challenges encountered during the construction of the test platform.The technical obstacles included ultrahigh-speed traction,reliable braking,vehicle-tube aerodynamic coupling at 1 500 km/h,vacuum sealing and maintenance for the 1 620 m tube,and millimeter-level precision measurement and control.Managerially,the project faced the lack of international precedent,complex interdisciplinary collaboration,deep integration of civil engineering techniques with customized scientific equipment,and the challenge of balancing research flexibility with engineering standardization.To overcome issues such as a lack of experience,design-construction coordination difficulties,and dual-attribute management conflicts,the team drew upon management practices from international megascience projects such as LCLS,the Centrifugal Hypergravity and Interdisciplinary Experiment Facility,the Shanghai Synchrotron Radiation Facility,and FAST.The following management innovations were implemented:① integration of research and engineering,with joint teams established at the proposal stage to co-design parameters and collaboratively address vacuum sealing and long-tube thermal expansion issues—through advanced welding techniques,precision support systems,and intelligent pressure monitoring were used to ensure vacuum reliability and minimize design changes throughout construction.② Multiparty collaboration,featuring regular coordination meetings among research,design,construction,and equipment supply teams,which accelerated the resolution of issues such as motor support manufacturing,material selection,and interface conflicts,improving decision-making efficiency and project progress.③ Iterative development and prototype validation,such as a 60 m linear motor prototype section used for installation,insulation,and inverter system testing.Here,prototype results were continually fed back to optimize the design.After aerodynamic optimization,the surface temperature of the tube vehicle at 0.005 atm remained under 100℃,meeting the desired targets.④ Precision measurement and digital quality control:when a 3.5 mm deviation was detected in the centerline of a 160 m tube section,the project team immediately suspended the lifting operation and organized an evaluation.By introducing a third-party measurement team and advanced testing technologies,a unified coordinate system was established and staged monitoring was carried out,ensuring the high-precision alignment required for subsequent experiments.[Results]Implementation of these management models yielded substantial outcomes.The platform achieved phased design objectives,with all major performance metrics(traction,braking,aerodynamics,vacuum,and assembly accuracy)meeting expectations.Collaborative and iterative management sharply reduced rework and failures,ensuring on-schedule delivery.The resulting management innovations are replicable and scalable,providing a model for complex,interdisciplinary engineering projects.While further refinement is still needed for engineering standardization,platform management mechanisms,and international collaboration,this project has effectively resolved the core technical and managerial challenges facing this new class of test platform.[Conclusions]Combining management innovation and technical optimization markedly enhanced the efficiency and quality of the super-high-speed evacuated tube maglev platform,establishing a universal management framework for advanced transportation infrastructure.The integration of research and engineering practices,multiparty collaboration,iterative prototyping,and precision measurement constitutes a systematic management model for next-generation transportation systems.These results will continue to drive engineering progress and sustainable development in the field of high-speed maglev systems,accelerating the advancement of rail transit toward higher speeds,greater efficiency,and global connectivity.

Currently, object detection-based rail fastener defect detection methods still face challenges such as limited detection categories, insufficient accuracy, and high computational complexity. To this end, the YOLOv8n-FDD, an advanced multi-category fastener defect detection model designed upon the YOLOv8n with comprehensive optimizations is developed in this paper. Concretely, by introducing the CUT-based style transfer model to generate diverse defect samples, the concern due to imbalanced distribution of sample categories is effectively alleviated. The CA mechanism is incorporated to enhance the feature extraction capability, and the bounding box loss function is further upgraded to improve the model’s generalization performance. With respect to efficiency, the Conv and c2f modules of the YOLOv8n model are, respectively, replaced with the GSConv and VoVGSPCP modules, accordingly achieving a lightweight design. Comparative experimental results demonstrate that the presented YOLOv8n-FDD model outperforms several classic object detection models in terms of detection accuracy, detection speed, model size, and computational complexity.