The rapid expansion of railways,especially High-Speed Railways(HSRs),has drawn considerable interest from both academic and industrial sectors.To meet the future vision of smart rail communications,the rail transport ...The rapid expansion of railways,especially High-Speed Railways(HSRs),has drawn considerable interest from both academic and industrial sectors.To meet the future vision of smart rail communications,the rail transport industry must innovate in key technologies to ensure high-quality transmissions for passengers and railway operations.These systems must function effectively under high mobility conditions while prioritizing safety,ecofriendliness,comfort,transparency,predictability,and reliability.On the other hand,the proposal of 6 G wireless technology introduces new possibilities for innovation in communication technologies,which may truly realize the current vision of HSR.Therefore,this article gives a review of the current advanced 6 G wireless communication technologies for HSR,including random access and switching,channel estimation and beamforming,integrated sensing and communication,and edge computing.The main application scenarios of these technologies are reviewed,as well as their current research status and challenges,followed by an outlook on future development directions.展开更多
Based on the investigation of mechanical response and microstructure evolution of a commercial 7003 aluminum alloy under high-speed impact,a new simple and effective method was proposed to determine the critical strai...Based on the investigation of mechanical response and microstructure evolution of a commercial 7003 aluminum alloy under high-speed impact,a new simple and effective method was proposed to determine the critical strain required for the nucleation of adiabatic shear band(ASB).The deformation results of cylindrical and hat-shaped samples show that the critical strain required for ASB nucleation corresponds to the strain at the first local minimum after peak stress on the first derivative curve of true stress−true strain.The method of determining the critical strain for the nucleation of ASB through the first derivative of the flow stress curve is named the first derivative method.The proposed first derivative method is not only applicable to the 7003 aluminum alloy,but also to other metal materials,such as commercial purity titanium,WY-100 steel,and AM80 magnesium alloy.This proves that it has strong universality.展开更多
Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the...Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.展开更多
Ventilation systems are critical for improving the cabin environment in high-speed trains,and their interest has increased significantly.However,whether air supply non-verticality deteriorates the cabin air environmen...Ventilation systems are critical for improving the cabin environment in high-speed trains,and their interest has increased significantly.However,whether air supply non-verticality deteriorates the cabin air environment,and the flow mechanism behind it and the degree of deterioration are not known.This study first analyzes the interaction between deflection angle and cabin flow field characteristics and ventilation performance.The results revealed that the interior temperature and pollutant concentration decreased slightly with increasing deflection angle,but resulted in significant deterioration of thermal comfort and air quality.This is evidenced by an increase in both draught rate and non-uniformity coefficient,an increase in the number of measurement points that do not satisfy the micro-wind speed and temperature difference requirements by about 5% and 15%,respectively,and an increase in longitudinal penetration of pollutants by a factor of about 5 and the appearance of locking regions at the ends of cabin.The results also show that changing the deflection pattern only affects the region of deterioration and does not essentially improve this deterioration.This study can provide reference and help for the ventilation design of high-speed trains.展开更多
This study compares the microstructural evolution,dynamic recrystallization(DRX)behavior,tensile properties,and age-hardenability between the newly developed high-speed-extrudable BA56 alloy and those of the widely re...This study compares the microstructural evolution,dynamic recrystallization(DRX)behavior,tensile properties,and age-hardenability between the newly developed high-speed-extrudable BA56 alloy and those of the widely recognized AZ31 alloy in industry.Unlike the AZ31 alloy,which retains partially unrecrystallized grains,the high-speed-extruded BA56 alloy demonstrates a coarser but entirely recrystallized and more homogeneous microstructure.The fine-grained structure and abundant Mg_(3)Bi_(2) particles in the BA56 extrusion billet significantly enhance its DRX behavior,thus enabling rapid and complete recrystallization during extrusion.The BA56 alloy contains band-like fragmented Mg_(3)Bi_(2) particles and numerous fine Mg_(3)Bi_(2) particles distributed throughout the material,in contrast to the sparse Al_(8)Mn_(5) particles in the AZ31 alloy.These features contribute to superior mechanical properties of the BA56 alloy,which achieves tensile yield and ultimate tensile strengths of 205 and 292 MPa,respectively,compared to 196 and 270 MPa for the AZ31 alloy.The superior strength of the BA56 alloy,even with its coarser grain size,can be explained by its elevated Hall-Petch constant and the strengthening contribution from the fine Mg_(3)Bi_(2) particles.Additionally,the BA56 alloy demonstrates significant age-hardenability,achieving a 22%enhancement in hardness following T5 aging,attributed to the precipitation of nanoscale Mg_(3)Bi_(2) and Mg_(17)Al_(12) phases.By contrast,the AZ31 alloy shows minimal hardening due to the absence of precipitate formation during aging.These findings suggest that the BA56 alloy is a promising candidate for the production of extruded Mg components requiring a combination of high productivity,superior mechanical performance,and wide-ranging process adaptability.展开更多
High-speed imaging is crucial for understanding the transient dynamics of the world,but conventional frame-by-frame video acquisition is limited by specialized hardware and substantial data storage requirements.We int...High-speed imaging is crucial for understanding the transient dynamics of the world,but conventional frame-by-frame video acquisition is limited by specialized hardware and substantial data storage requirements.We introduce“SpeedShot,”a computational imaging framework for efficient high-speed video imaging.SpeedShot features a low-speed dual-camera setup,which simultaneously captures two temporally coded snapshots.Cross-referencing these two snapshots extracts a multiplexed temporal gradient image,producing a compact and multiframe motion representation for video reconstruction.Recognizing the unique temporal-only modulation model,we propose an explicable motion-guided scale-recurrent transformer for video decoding.It exploits cross-scale error maps to bolster the cycle consistency between predicted and observed data.Evaluations on both simulated datasets and real imaging setups demonstrate SpeedShot’s effectiveness in video-rate up-conversion,with pronounced improvement over video frame interpolation and deblurring methods.The proposed framework is compatible with commercial low-speed cameras,offering a versatile low-bandwidth alternative for video-related applications,such as video surveillance and sports analysis.展开更多
The influence of ramps on the transient rolling contact characteristics and damage mechanisms of switch rails remains unclear,presenting substantial challenges to the safety of railway operations.To this end,this pape...The influence of ramps on the transient rolling contact characteristics and damage mechanisms of switch rails remains unclear,presenting substantial challenges to the safety of railway operations.To this end,this paper constructs a transient rolling contact finite element model of the wheel-rail in switch under different ramps using ANSYS/LSDYNA method,and analyzes the tribology and damage characteristics when the wheel passes through the switch at a uniform speed.Our research findings reveal that the vibration induced in the switch rail during the wheel load transfer process leads to a step-like increase in the contact force.Moreover,the interaction between the wheel and the rail primarily involves slip contact,which may significantly contribute to the formation of corrugations on the switch rail.Additionally,the presence of large ramps exacerbates switch rail wear and rolling contact fatigue,resulting in a notable 13.2%increase in switch rail damage under 40‰ramp conditions compared to flat(0‰ramp)conditions.Furthermore,the large ramps can alter the direction of crack propagation,ultimately causing surface spalling of the rail.Therefore,large ramps intensify the dynamic interactions during the wheel load transfer process,further aggravating the crack and spalling damage to the switch rails.展开更多
Currently,the global 5G network,cloud computing,and data center industries are experiencing rapid development.The continuous growth of data center traffic has driven the vigorous progress in high-speed optical transce...Currently,the global 5G network,cloud computing,and data center industries are experiencing rapid development.The continuous growth of data center traffic has driven the vigorous progress in high-speed optical transceivers for optical interconnection within data centers.The electro-absorption modulated laser(EML),which is widely used in optical fiber communications,data centers,and high-speed data transmission systems,represents a high-performance photoelectric conversion device.Compared to traditional directly modulated lasers(DMLs),EMLs demonstrate lower frequency chirp and higher modulation bandwidth,enabling support for higher data rates and longer transmission distances.This article introduces the composition,working principles,manufacturing processes,and applications of EMLs.It reviews the progress on advanced indium phosphide(InP)-based EML devices from research institutions worldwide,while summarizing and comparing data transmission rates and key technical approaches across various studies.展开更多
Purpose–Regarding that Ultraviolet radiation,pollutant adsorption,and environmental changes may be the main reasons for the aging and yellowing on windshield rubber in high-speed trains,countermeasures are proposed t...Purpose–Regarding that Ultraviolet radiation,pollutant adsorption,and environmental changes may be the main reasons for the aging and yellowing on windshield rubber in high-speed trains,countermeasures are proposed to solve the aging and yellowing of windshield rubber and reduce the adverse effects caused by rubber yellowing.Design/methodology/approach–Scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)were used to test the yellowed windshield rubber.Aging tests,including UVaging,natural aging and salt spray aging,were conducted to analyze the effects of aging on the windshield rubber.Different cleaning agents were selected to soak the windshield rubber,and the quality,hardness,and surface appearance of the rubber samples were tested.Findings–After UV aging,antioxidants migrated to the surface of the windshield rubber,but due to oxidation failure,they could not capture free radicals,leading to continued oxidation reactions within the material and resulting in yellowing of the rubber in a short period of time.Originality/value–Cleaning agents have a minimal impact on windshield rubber,UV aging has the greatest impact and natural aging is a gradual and slow deterioration process.Through daily deep cleaning and maintenance with protective agents at regular intervals,the deterioration of windshield rubber yellowing in high-speed trains can be effectively suppressed.展开更多
Purpose–This paper investigates how high-speed rail(HSR)influences socioeconomic inequality by providing the first systematic bibliometric review of research trends,methodological approaches and thematic structures.I...Purpose–This paper investigates how high-speed rail(HSR)influences socioeconomic inequality by providing the first systematic bibliometric review of research trends,methodological approaches and thematic structures.It examines whether HSR fosters balanced regional development or reinforces spatial disparities.Design/methodology/approach–Using the Bibliometrix R package,237 records were retrieved from the Web of Science(1985–2024).Citation indicators,keyword co-occurrence and collaboration networks were combined with natural language processing(NLP)to classify studies by territorial scale,methodology,economic variables and inequality outcomes.Findings–The paper offers the first structured overview of how the literature conceptualizes the link between HSR and inequality.It highlights persistent gaps–scarcity of city-level analyses,limited socioeconomic indicators and reliance on Chinese case studies–providing a foundation for more comparative and interdisciplinary research.Originality/value–This paper contributes by offering a structured overview of how the literature has conceptualized and measured the relationship between HSR and inequality.By identifying persistent research gaps–such as the scarcity of city-level analyses,limited use of socioeconomic indicators,and overreliance on Chinese case studies–it provides a foundation for more comparative and interdisciplinary approaches.The study informs policymakers and researchers on how to design future infrastructure projects that balance efficiency with equity.展开更多
Purpose–High-speed turnouts are more complex in structure and thus may cause abnormal vibration of highspeed train car body,affecting driving safety and passenger riding experience.Therefore,it is necessary to analyz...Purpose–High-speed turnouts are more complex in structure and thus may cause abnormal vibration of highspeed train car body,affecting driving safety and passenger riding experience.Therefore,it is necessary to analyze the data characteristics of continuous hunting of high-speed trains passing through turnouts and propose a diagnostic method for engineering applications.Design/methodology/approach–First,Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)is performed to determine the first characteristic component of the car body’s lateral acceleration.Then,the Short-Time Fourier Transform(STFT)is performed to calculate the marginal spectra.Finally,the presence of a continuous hunting problem is determined based on the results of the comparison calculations and diagnostic thresholds.To improve computational efficiency,permutation entropy(PE)is used as a fast indicator to identify turnouts with potential problems.Findings–Under continuous hunting conditions,the PE is less than 0.90;the ratio of the maximum peak value of the signal component to the original signal peak value exceeded 0.7,and there is an energy band in the STFT time-frequency map,which corresponds to a frequency distribution range of 1–2 Hz.Originality/value–The research results have revealed the lateral vibration characteristics of the high-speed train’s car body during continuous hunting when passing through turnouts.On this basis,an effective diagnostic method has been proposed.With a focus on practical engineering applications,a rapid screening index for identifying potential issues has been proposed,significantly enhancing the efficiency of diagnostic processes.展开更多
Following the fundamental characteristics of the porosity windbreak,this study suggests a new numerical investigation method for the wind field of the windbreak based on the porous medium physical model.This method ca...Following the fundamental characteristics of the porosity windbreak,this study suggests a new numerical investigation method for the wind field of the windbreak based on the porous medium physical model.This method can transform the reasonable matching problem of the porosity and windproof performance of the windbreak into a study of the relationship between the resistance coefficient of the porous medium and the aerodynamic load of the train.This study examines the influence of the hole type on the wind field behind the porosity windbreak.Then,the relationship between the resistance coefficient of the porous medium,the porosity of the windbreak,and the aerodynamic loads of the train is investigated.The results show that the porous media physical model can be used instead of the windbreak geometry to study the windbreak-train aerodynamic performance,and the process of using this method is suggested.展开更多
With technological advancements,high-speed rail has emerged as a prevalent mode of transportation.During travel,passengers exhibit a growing demand for streaming media services.However,the high-speed mobile networks e...With technological advancements,high-speed rail has emerged as a prevalent mode of transportation.During travel,passengers exhibit a growing demand for streaming media services.However,the high-speed mobile networks environment poses challenges,including frequent base station handoffs,which significantly degrade wireless network transmission performance.Improving transmission efficiency in high-speed mobile networks and optimizing spatiotemporal wireless resource allocation to enhance passengers’media experiences are key research priorities.To address these issues,we propose an Adaptive Cross-Layer Optimization Transmission Method with Environment Awareness(ACOTM-EA)tailored for high-speed rail streaming media.Within this framework,we develop a channel quality prediction model utilizing Kalman filtering and an algorithm to identify packet loss causes.Additionally,we introduce a proactive base station handoffstrategy to minimize handoffrelated disruptions and optimize resource distribution across adjacent base stations.Moreover,this study presents a wireless resource allocation approach based on an enhanced genetic algorithm,coupled with an adaptive bitrate selection mechanism,to maximize passenger Quality of Experience(QoE).To evaluate the proposed method,we designed a simulation experiment and compared ACOTM-EA with established algorithms.Results indicate that ACOTM-EA improves throughput by 11%and enhances passengers’media experience by 5%.展开更多
With the rapid development of high-speed railway tunnel construction mileage and technology,the construction of the tunnel face is a key part of tunnel construction in high-speed railway tunnel projects.As mechanizati...With the rapid development of high-speed railway tunnel construction mileage and technology,the construction of the tunnel face is a key part of tunnel construction in high-speed railway tunnel projects.As mechanization and intelligence levels continue to increase,supporting equipment mainly includes rock drilling trolleys,arch installation trolleys,wet spraying robots,anchor trolleys,etc.To address the issues of high construction costs and the need to replace equipment for different processes,this paper designs an economical and practical multi-functional integrated trolley for high-speed railway double-track tunnels based on engineering cases.This trolley can adapt to various tunnel face excavation methods such as the full-face method and the bench method,enabling integrated functions such as drilling and blasting holes,anchor holes,advance grouting holes,pipe roof construction,charging,anchor installation and grouting,and arch mesh installation.This reduces the number of operators,improves the working environment of high-speed railway tunnels,lowers construction costs,and enhances construction efficiency.展开更多
High-Speed Trains (HSTs) have emerged as a mainstream mode of transportation in China, owing to their exceptional safety and efficiency. Ensuring the reliable operation of HSTs is of paramount economic and societal im...High-Speed Trains (HSTs) have emerged as a mainstream mode of transportation in China, owing to their exceptional safety and efficiency. Ensuring the reliable operation of HSTs is of paramount economic and societal importance. As critical rotating mechanical components of the transmission system, bearings make their fault diagnosis a topic of extensive attention. This paper provides a systematic review of image encoding-based bearing fault diagnosis methods tailored to the condition monitoring of HSTs. First, it categorizes the image encoding techniques applied in the field of bearing fault diagnosis. Then, a review of state-of-the-art studies has been presented, encompassing both monomodal image conversion and multimodal image fusion approaches. Finally, it highlights current challenges and proposes future research directions to advance intelligent fault diagnosis in HSTs, aiming to provide a valuable reference for researchers and engineers in the field of intelligent operation and maintenance.展开更多
The integration of high-speed railway communication systems with 5G technology is widely recognized as a significant development.Due to the considerable mobility of trains and the complex nature of the environment,the...The integration of high-speed railway communication systems with 5G technology is widely recognized as a significant development.Due to the considerable mobility of trains and the complex nature of the environment,the wireless channel exhibits non-stationary characteristics and fast time-varying characteristics,which presents significant hurdles in terms of channel estimation.In addition,the use of massive MIMO technology in the context of 5G networks also leads to an increase in the complexity of estimation.To address the aforementioned issues,this paper presents a novel approach for channel estimation in high mobility scenarios using a reconstruction and recovery network.In this method,the time-frequency response of the channel is considered as a two-dimensional image.The Fast Super-Resolution Convolution Neural Network(FSRCNN)is used to first reconstruct channel images.Next,the Denoising Convolution Neural Network(DnCNN)is applied to reduce the channel noise and improve the accuracy of channel estimation.Simulation results show that the accuracy of the channel estimation model surpasses that of the standard channel estimation method,while also exhibiting reduced algorithmic complexity.展开更多
The dynamic performance of high-speed trains is significantly influenced by sudden changes in aerodynamic loads(ADLs)when exiting a tunnel in a windy environment.Focusing on a double-track tunnel under construction in...The dynamic performance of high-speed trains is significantly influenced by sudden changes in aerodynamic loads(ADLs)when exiting a tunnel in a windy environment.Focusing on a double-track tunnel under construction in a mountain railway,we established an aerodynamic model involving a train exiting the tunnel,and verified it in the Fluent environment.Overset mesh technology was adopted to characterize the train’s movement.The flow field involving the train,tunnel,and crosswinds was simulated using the Reynolds-averaged turbulence model.Then,we built a comprehensive train-track coupled dynamic model considering the influences of ADLs,to investigate the vehicles’dynamic responses.The aerodynamics and dynamic behaviors of the train when affected by crosswinds with different velocities and directions are analyzed and discussed.The results show that the near-wall side crosswind leads to sharper variations in ADLs than the far-wall side crosswind.The leading vehicle suffers from more severe ADLs than other vehicles,which worsens the wheel-rail interaction and causes low-frequency vibration of the car body.When the crosswind velocity exceeds 20 m/s,significant wheel-rail impacts occur,and the running safety of the train worsens rapidly.展开更多
Automated detection of suspended anomalous objects on high-speed railway catenary systems using computer vision-based technology is a critical task for ensuring railway transportation safety. Despite the critical impo...Automated detection of suspended anomalous objects on high-speed railway catenary systems using computer vision-based technology is a critical task for ensuring railway transportation safety. Despite the critical importance of this task, conventional vision-based foreign object detection methodologies have predominantly concentrated on image data, neglecting the exploration and integration of textual information. The currently popular multimodal model Contrastive Language-Image Pre-training (CLIP) employs contrastive learning to enable simultaneous understanding of both visual and textual modalities. Drawing inspiration from CLIP’s capabilities, this paper introduces a novel CLIP-based multimodal foreign object detection model tailored for railway applications, referred to as Railway-CLIP. This model leverages CLIP’s robust generalization capabilities to enhance performance in the context of catenary foreign object detection. The Railway-CLIP model is primarily composed of an image encoder and a text encoder. Initially, the Segment Anything Model (SAM) is employed to preprocess raw images, identifying candidate bounding boxes that may contain foreign objects. Both the original images and the detected candidate bounding boxes are subsequently fed into the image encoder to extract their respective visual features. In parallel, distinct prompt templates are crafted for both the original images and the candidate bounding boxes to serve as textual inputs. These prompts are then processed by the text encoder to derive textual features. The image and text encoders collaboratively project the multimodal features into a shared semantic space, facilitating the computation of similarity scores between visual and textual representations. The final detection results are determined based on these similarity scores, ensuring a robust and accurate identification of anomalous objects. Extensive experiments on our collected Railway Anomaly Dataset (RAD) demonstrate that the proposed Railway-CLIP outperforms previous state-of-the-art methods, achieving 97.25% AUROC and 92.66% F1-score, thereby validating the effectiveness and superiority of the proposed approach in real-world high-speed railway anomaly detection scenarios.展开更多
基金National Natural Science Foundation of China(U2468201,62122012,62221001).
文摘The rapid expansion of railways,especially High-Speed Railways(HSRs),has drawn considerable interest from both academic and industrial sectors.To meet the future vision of smart rail communications,the rail transport industry must innovate in key technologies to ensure high-quality transmissions for passengers and railway operations.These systems must function effectively under high mobility conditions while prioritizing safety,ecofriendliness,comfort,transparency,predictability,and reliability.On the other hand,the proposal of 6 G wireless technology introduces new possibilities for innovation in communication technologies,which may truly realize the current vision of HSR.Therefore,this article gives a review of the current advanced 6 G wireless communication technologies for HSR,including random access and switching,channel estimation and beamforming,integrated sensing and communication,and edge computing.The main application scenarios of these technologies are reviewed,as well as their current research status and challenges,followed by an outlook on future development directions.
基金National Natural Science Foundation of China (No. U20A20275)Natural Science Foundation of Hunan Province,China (No. 2021JJ40096)。
文摘Based on the investigation of mechanical response and microstructure evolution of a commercial 7003 aluminum alloy under high-speed impact,a new simple and effective method was proposed to determine the critical strain required for the nucleation of adiabatic shear band(ASB).The deformation results of cylindrical and hat-shaped samples show that the critical strain required for ASB nucleation corresponds to the strain at the first local minimum after peak stress on the first derivative curve of true stress−true strain.The method of determining the critical strain for the nucleation of ASB through the first derivative of the flow stress curve is named the first derivative method.The proposed first derivative method is not only applicable to the 7003 aluminum alloy,but also to other metal materials,such as commercial purity titanium,WY-100 steel,and AM80 magnesium alloy.This proves that it has strong universality.
基金National Key R&D Program of China(2022YFB2602900)R&D Fund Project of China Academy of Railway Sciences Corporation Limited(2021YJ084)+2 种基金Project of Science and Technology R&D Program of China Railway(2016G002-K)R&D Fund Project of China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.(2021)R&D Fund Project of China Railway Shanghai Group(2021141).
文摘Purpose–The bridge expansion joint(BEJ)is a key device for accommodating spatial displacement at the beam end,and for providing vertical support for running trains passing over the gap between the main bridge and the approach bridge.For long-span railway bridges,it must also be coordinated with rail expansion joint(REJ),which is necessary to accommodate the expansion and contraction of,and reducing longitudinal stress in,the rails.The main aim of this study is to present analysis of recent developments in the research and application of BEJs in high-speed railway(HSR)long-span bridges in China,and to propose a performance-based integral design method for BEJs used with REJs,from both theoretical and engineering perspectives.Design/methodology/approach–The study first presents a summary on the application and maintenance of BEJs in HSR long-span bridges in China representing an overview of their state of development.Results of a survey of typical BEJ faults were analyzed,and field testing was conducted on a railway cable-stayed bridge in order to obtain information on the major mechanical characteristics of its BEJ under train load.Based on the above,a performance-based integral design method for BEJs with maximum expansion range 1600 mm(±800 mm),was proposed,covering all stages from overall conceptual design to consideration of detailed structural design issues.The performance of the novel BEJ design thus derived was then verified via theoretical analysis under different scenarios,full-scale model testing,and field testing and commissioning.Findings–Two major types of BEJs,deck-type and through-type,are used in HSR long-span bridges in China.Typical BEJ faults were found to mainly include skewness of steel sleepers at the bridge gap,abnormally large longitudinal frictional resistance,and flexural deformation of the scissor mechanisms.These faults influence BEJ functioning,and thus adversely affect track quality and train running performance at the beam end.Due to their simple and integral structure,deck-type BEJs with expansion range 1200 mm(±600 mm)or less have been favored as a solution offering improved operational conditions,and have emerged as a standard design.However,when the expansion range exceeds the above-mentioned value,special design work becomes necessary.Therefore,based on engineering practice,a performance-based integral design method for BEJs used with REJs was proposed,taking into account four major categories of performance requirements,i.e.,mechanical characteristics,train running quality,durability and insulation performance.Overall BEJ design must mainly consider component strength and the overall stiffness of BEJ;the latter factor in particular has a decisive influence on train running performance at the beam end.Detailed BEJ structural design must stress minimization of the frictional resistance of its sliding surface.The static and dynamic performance of the newlydesigned BEJ with expansion range 1600 mm have been confirmed to be satisfactory,via numerical simulation,full-scale model testing,and field testing and commissioning.Originality/value–This research provides a broad overview of the status of BEJs with large expansion range in HSR long-span bridges in China,along with novel insights into their design.
基金Project(12372049)supported by the National Natural Science Foundation of ChinaProject(2682023ZTPY036)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2023TPL-T06)supported by the Independent Project of State Key Laboratory of Rail Transit Vehicle System,China。
文摘Ventilation systems are critical for improving the cabin environment in high-speed trains,and their interest has increased significantly.However,whether air supply non-verticality deteriorates the cabin air environment,and the flow mechanism behind it and the degree of deterioration are not known.This study first analyzes the interaction between deflection angle and cabin flow field characteristics and ventilation performance.The results revealed that the interior temperature and pollutant concentration decreased slightly with increasing deflection angle,but resulted in significant deterioration of thermal comfort and air quality.This is evidenced by an increase in both draught rate and non-uniformity coefficient,an increase in the number of measurement points that do not satisfy the micro-wind speed and temperature difference requirements by about 5% and 15%,respectively,and an increase in longitudinal penetration of pollutants by a factor of about 5 and the appearance of locking regions at the ends of cabin.The results also show that changing the deflection pattern only affects the region of deterioration and does not essentially improve this deterioration.This study can provide reference and help for the ventilation design of high-speed trains.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korea government(MSIT)(Nos.RS-2024–00351052 and RS-2024–00450561).
文摘This study compares the microstructural evolution,dynamic recrystallization(DRX)behavior,tensile properties,and age-hardenability between the newly developed high-speed-extrudable BA56 alloy and those of the widely recognized AZ31 alloy in industry.Unlike the AZ31 alloy,which retains partially unrecrystallized grains,the high-speed-extruded BA56 alloy demonstrates a coarser but entirely recrystallized and more homogeneous microstructure.The fine-grained structure and abundant Mg_(3)Bi_(2) particles in the BA56 extrusion billet significantly enhance its DRX behavior,thus enabling rapid and complete recrystallization during extrusion.The BA56 alloy contains band-like fragmented Mg_(3)Bi_(2) particles and numerous fine Mg_(3)Bi_(2) particles distributed throughout the material,in contrast to the sparse Al_(8)Mn_(5) particles in the AZ31 alloy.These features contribute to superior mechanical properties of the BA56 alloy,which achieves tensile yield and ultimate tensile strengths of 205 and 292 MPa,respectively,compared to 196 and 270 MPa for the AZ31 alloy.The superior strength of the BA56 alloy,even with its coarser grain size,can be explained by its elevated Hall-Petch constant and the strengthening contribution from the fine Mg_(3)Bi_(2) particles.Additionally,the BA56 alloy demonstrates significant age-hardenability,achieving a 22%enhancement in hardness following T5 aging,attributed to the precipitation of nanoscale Mg_(3)Bi_(2) and Mg_(17)Al_(12) phases.By contrast,the AZ31 alloy shows minimal hardening due to the absence of precipitate formation during aging.These findings suggest that the BA56 alloy is a promising candidate for the production of extruded Mg components requiring a combination of high productivity,superior mechanical performance,and wide-ranging process adaptability.
基金supported by the National Natural Science Foundation of China(Grant No.62305184)the Basic and Applied Basic Research Foundation of Guangdong Province(Grant No.2023A1515012932)+7 种基金the Science,Technology,and Innovation Commission of Shenzhen Municipality(Grant No.JCYJ20241202123919027)the Major Key Project of Pengcheng Laboratory(Grant No.PCL2024A1)the Science Fund for Distinguished Young Scholars of Zhejiang Province(Grant No.LR23F010001)the Research Center for Industries of the Future(RCIF)at Westlake University and and the Key Project of Westlake Institute for Optoelectronics(Grant No.2023GD007)the Zhejiang“Pioneer”and“Leading Goose”R&D Program(Grant Nos.2024SDXHDX0006 and 2024C03182)the Ningbo Science and Technology Bureau“Science and Technology Yongjiang 2035”Key Technology Breakthrough Program(Grant No.2024Z126)the Research Grants Council of the Hong Kong Special Administrative Region,China(Grant Nos.C5031-22G,CityU11310522,and CityU11300123)the City University of Hong Kong(Grant No.9610628).
文摘High-speed imaging is crucial for understanding the transient dynamics of the world,but conventional frame-by-frame video acquisition is limited by specialized hardware and substantial data storage requirements.We introduce“SpeedShot,”a computational imaging framework for efficient high-speed video imaging.SpeedShot features a low-speed dual-camera setup,which simultaneously captures two temporally coded snapshots.Cross-referencing these two snapshots extracts a multiplexed temporal gradient image,producing a compact and multiframe motion representation for video reconstruction.Recognizing the unique temporal-only modulation model,we propose an explicable motion-guided scale-recurrent transformer for video decoding.It exploits cross-scale error maps to bolster the cycle consistency between predicted and observed data.Evaluations on both simulated datasets and real imaging setups demonstrate SpeedShot’s effectiveness in video-rate up-conversion,with pronounced improvement over video frame interpolation and deblurring methods.The proposed framework is compatible with commercial low-speed cameras,offering a versatile low-bandwidth alternative for video-related applications,such as video surveillance and sports analysis.
基金Project(2023YFB2604304)supported by the National Key R&D Program of ChinaProjects(52122810,51978586,51778542,U23A20666,52472458)supported by the National Natural Science Foundation of China+1 种基金Project(K2022G034)supported by the Technology Research and Development Program of China National Railway Group Co.Ltd.Projects(2020JDJQ0033,2023NSFSC0884)supported by Sichuan Province Science and Technology Support Program,China。
文摘The influence of ramps on the transient rolling contact characteristics and damage mechanisms of switch rails remains unclear,presenting substantial challenges to the safety of railway operations.To this end,this paper constructs a transient rolling contact finite element model of the wheel-rail in switch under different ramps using ANSYS/LSDYNA method,and analyzes the tribology and damage characteristics when the wheel passes through the switch at a uniform speed.Our research findings reveal that the vibration induced in the switch rail during the wheel load transfer process leads to a step-like increase in the contact force.Moreover,the interaction between the wheel and the rail primarily involves slip contact,which may significantly contribute to the formation of corrugations on the switch rail.Additionally,the presence of large ramps exacerbates switch rail wear and rolling contact fatigue,resulting in a notable 13.2%increase in switch rail damage under 40‰ramp conditions compared to flat(0‰ramp)conditions.Furthermore,the large ramps can alter the direction of crack propagation,ultimately causing surface spalling of the rail.Therefore,large ramps intensify the dynamic interactions during the wheel load transfer process,further aggravating the crack and spalling damage to the switch rails.
基金supported by the Strategic Priority Research Program of CAS(Grant No.XDB43020202)the Natural Science Foundation of China(Grant Nos.61934007,62274153,62090053).
文摘Currently,the global 5G network,cloud computing,and data center industries are experiencing rapid development.The continuous growth of data center traffic has driven the vigorous progress in high-speed optical transceivers for optical interconnection within data centers.The electro-absorption modulated laser(EML),which is widely used in optical fiber communications,data centers,and high-speed data transmission systems,represents a high-performance photoelectric conversion device.Compared to traditional directly modulated lasers(DMLs),EMLs demonstrate lower frequency chirp and higher modulation bandwidth,enabling support for higher data rates and longer transmission distances.This article introduces the composition,working principles,manufacturing processes,and applications of EMLs.It reviews the progress on advanced indium phosphide(InP)-based EML devices from research institutions worldwide,while summarizing and comparing data transmission rates and key technical approaches across various studies.
文摘Purpose–Regarding that Ultraviolet radiation,pollutant adsorption,and environmental changes may be the main reasons for the aging and yellowing on windshield rubber in high-speed trains,countermeasures are proposed to solve the aging and yellowing of windshield rubber and reduce the adverse effects caused by rubber yellowing.Design/methodology/approach–Scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)were used to test the yellowed windshield rubber.Aging tests,including UVaging,natural aging and salt spray aging,were conducted to analyze the effects of aging on the windshield rubber.Different cleaning agents were selected to soak the windshield rubber,and the quality,hardness,and surface appearance of the rubber samples were tested.Findings–After UV aging,antioxidants migrated to the surface of the windshield rubber,but due to oxidation failure,they could not capture free radicals,leading to continued oxidation reactions within the material and resulting in yellowing of the rubber in a short period of time.Originality/value–Cleaning agents have a minimal impact on windshield rubber,UV aging has the greatest impact and natural aging is a gradual and slow deterioration process.Through daily deep cleaning and maintenance with protective agents at regular intervals,the deterioration of windshield rubber yellowing in high-speed trains can be effectively suppressed.
文摘Purpose–This paper investigates how high-speed rail(HSR)influences socioeconomic inequality by providing the first systematic bibliometric review of research trends,methodological approaches and thematic structures.It examines whether HSR fosters balanced regional development or reinforces spatial disparities.Design/methodology/approach–Using the Bibliometrix R package,237 records were retrieved from the Web of Science(1985–2024).Citation indicators,keyword co-occurrence and collaboration networks were combined with natural language processing(NLP)to classify studies by territorial scale,methodology,economic variables and inequality outcomes.Findings–The paper offers the first structured overview of how the literature conceptualizes the link between HSR and inequality.It highlights persistent gaps–scarcity of city-level analyses,limited socioeconomic indicators and reliance on Chinese case studies–providing a foundation for more comparative and interdisciplinary research.Originality/value–This paper contributes by offering a structured overview of how the literature has conceptualized and measured the relationship between HSR and inequality.By identifying persistent research gaps–such as the scarcity of city-level analyses,limited use of socioeconomic indicators,and overreliance on Chinese case studies–it provides a foundation for more comparative and interdisciplinary approaches.The study informs policymakers and researchers on how to design future infrastructure projects that balance efficiency with equity.
基金support from the funds of National Natural Science Foundation of China(52308473)China Academy of Railway Science Corporation Limited(2022YJ192)are gratefully acknowledged。
文摘Purpose–High-speed turnouts are more complex in structure and thus may cause abnormal vibration of highspeed train car body,affecting driving safety and passenger riding experience.Therefore,it is necessary to analyze the data characteristics of continuous hunting of high-speed trains passing through turnouts and propose a diagnostic method for engineering applications.Design/methodology/approach–First,Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)is performed to determine the first characteristic component of the car body’s lateral acceleration.Then,the Short-Time Fourier Transform(STFT)is performed to calculate the marginal spectra.Finally,the presence of a continuous hunting problem is determined based on the results of the comparison calculations and diagnostic thresholds.To improve computational efficiency,permutation entropy(PE)is used as a fast indicator to identify turnouts with potential problems.Findings–Under continuous hunting conditions,the PE is less than 0.90;the ratio of the maximum peak value of the signal component to the original signal peak value exceeded 0.7,and there is an energy band in the STFT time-frequency map,which corresponds to a frequency distribution range of 1–2 Hz.Originality/value–The research results have revealed the lateral vibration characteristics of the high-speed train’s car body during continuous hunting when passing through turnouts.On this basis,an effective diagnostic method has been proposed.With a focus on practical engineering applications,a rapid screening index for identifying potential issues has been proposed,significantly enhancing the efficiency of diagnostic processes.
基金Projects(52302447,52388102,52372369)supported by the National Natural Science Foundation of China。
文摘Following the fundamental characteristics of the porosity windbreak,this study suggests a new numerical investigation method for the wind field of the windbreak based on the porous medium physical model.This method can transform the reasonable matching problem of the porosity and windproof performance of the windbreak into a study of the relationship between the resistance coefficient of the porous medium and the aerodynamic load of the train.This study examines the influence of the hole type on the wind field behind the porosity windbreak.Then,the relationship between the resistance coefficient of the porous medium,the porosity of the windbreak,and the aerodynamic loads of the train is investigated.The results show that the porous media physical model can be used instead of the windbreak geometry to study the windbreak-train aerodynamic performance,and the process of using this method is suggested.
基金substantially supported by the National Natural Science Foundation of China under Grant No.62002263in part by Tianjin Municipal Education Commission Research Program Project under 2022KJ012Tianjin Science and Technology Program Projects:24YDTPJC00630.
文摘With technological advancements,high-speed rail has emerged as a prevalent mode of transportation.During travel,passengers exhibit a growing demand for streaming media services.However,the high-speed mobile networks environment poses challenges,including frequent base station handoffs,which significantly degrade wireless network transmission performance.Improving transmission efficiency in high-speed mobile networks and optimizing spatiotemporal wireless resource allocation to enhance passengers’media experiences are key research priorities.To address these issues,we propose an Adaptive Cross-Layer Optimization Transmission Method with Environment Awareness(ACOTM-EA)tailored for high-speed rail streaming media.Within this framework,we develop a channel quality prediction model utilizing Kalman filtering and an algorithm to identify packet loss causes.Additionally,we introduce a proactive base station handoffstrategy to minimize handoffrelated disruptions and optimize resource distribution across adjacent base stations.Moreover,this study presents a wireless resource allocation approach based on an enhanced genetic algorithm,coupled with an adaptive bitrate selection mechanism,to maximize passenger Quality of Experience(QoE).To evaluate the proposed method,we designed a simulation experiment and compared ACOTM-EA with established algorithms.Results indicate that ACOTM-EA improves throughput by 11%and enhances passengers’media experience by 5%.
文摘With the rapid development of high-speed railway tunnel construction mileage and technology,the construction of the tunnel face is a key part of tunnel construction in high-speed railway tunnel projects.As mechanization and intelligence levels continue to increase,supporting equipment mainly includes rock drilling trolleys,arch installation trolleys,wet spraying robots,anchor trolleys,etc.To address the issues of high construction costs and the need to replace equipment for different processes,this paper designs an economical and practical multi-functional integrated trolley for high-speed railway double-track tunnels based on engineering cases.This trolley can adapt to various tunnel face excavation methods such as the full-face method and the bench method,enabling integrated functions such as drilling and blasting holes,anchor holes,advance grouting holes,pipe roof construction,charging,anchor installation and grouting,and arch mesh installation.This reduces the number of operators,improves the working environment of high-speed railway tunnels,lowers construction costs,and enhances construction efficiency.
基金supported by the Fundamental Research Funds for the Central Universities(No.2024JBZX027)the National Natural Science Foundation of China(No.52375078).
文摘High-Speed Trains (HSTs) have emerged as a mainstream mode of transportation in China, owing to their exceptional safety and efficiency. Ensuring the reliable operation of HSTs is of paramount economic and societal importance. As critical rotating mechanical components of the transmission system, bearings make their fault diagnosis a topic of extensive attention. This paper provides a systematic review of image encoding-based bearing fault diagnosis methods tailored to the condition monitoring of HSTs. First, it categorizes the image encoding techniques applied in the field of bearing fault diagnosis. Then, a review of state-of-the-art studies has been presented, encompassing both monomodal image conversion and multimodal image fusion approaches. Finally, it highlights current challenges and proposes future research directions to advance intelligent fault diagnosis in HSTs, aiming to provide a valuable reference for researchers and engineers in the field of intelligent operation and maintenance.
基金funded in part by the National Natural Science Foundation of China(62261024 and U2001213)in part by National Key Research and Development Project(2020YFB1807204)+2 种基金in part by Science and Technology Project of Education Department of Jiangxi Province(GJJ214606 and GJJ2205201)in part by Key Laboratory of Universal Wireless Communications(BUPT),Ministry of Education,P.R.China(KFKT-2022101)in part by the Jiangxi Provincial Natural Science Foundation(20212BAB212001)。
文摘The integration of high-speed railway communication systems with 5G technology is widely recognized as a significant development.Due to the considerable mobility of trains and the complex nature of the environment,the wireless channel exhibits non-stationary characteristics and fast time-varying characteristics,which presents significant hurdles in terms of channel estimation.In addition,the use of massive MIMO technology in the context of 5G networks also leads to an increase in the complexity of estimation.To address the aforementioned issues,this paper presents a novel approach for channel estimation in high mobility scenarios using a reconstruction and recovery network.In this method,the time-frequency response of the channel is considered as a two-dimensional image.The Fast Super-Resolution Convolution Neural Network(FSRCNN)is used to first reconstruct channel images.Next,the Denoising Convolution Neural Network(DnCNN)is applied to reduce the channel noise and improve the accuracy of channel estimation.Simulation results show that the accuracy of the channel estimation model surpasses that of the standard channel estimation method,while also exhibiting reduced algorithmic complexity.
基金National Natural Science Foundation of China(No.52388102)New Cornerstone Science Foundation through the Xplorer Prize.
文摘The dynamic performance of high-speed trains is significantly influenced by sudden changes in aerodynamic loads(ADLs)when exiting a tunnel in a windy environment.Focusing on a double-track tunnel under construction in a mountain railway,we established an aerodynamic model involving a train exiting the tunnel,and verified it in the Fluent environment.Overset mesh technology was adopted to characterize the train’s movement.The flow field involving the train,tunnel,and crosswinds was simulated using the Reynolds-averaged turbulence model.Then,we built a comprehensive train-track coupled dynamic model considering the influences of ADLs,to investigate the vehicles’dynamic responses.The aerodynamics and dynamic behaviors of the train when affected by crosswinds with different velocities and directions are analyzed and discussed.The results show that the near-wall side crosswind leads to sharper variations in ADLs than the far-wall side crosswind.The leading vehicle suffers from more severe ADLs than other vehicles,which worsens the wheel-rail interaction and causes low-frequency vibration of the car body.When the crosswind velocity exceeds 20 m/s,significant wheel-rail impacts occur,and the running safety of the train worsens rapidly.
基金supported by the Technology Research and Development Program of China National Railway Group(Q2024T002)the Open Project Fund of National Engineering Research Center of Digital Construction and Evaluation Technology of Urban Rail Transit(2024023).
文摘Automated detection of suspended anomalous objects on high-speed railway catenary systems using computer vision-based technology is a critical task for ensuring railway transportation safety. Despite the critical importance of this task, conventional vision-based foreign object detection methodologies have predominantly concentrated on image data, neglecting the exploration and integration of textual information. The currently popular multimodal model Contrastive Language-Image Pre-training (CLIP) employs contrastive learning to enable simultaneous understanding of both visual and textual modalities. Drawing inspiration from CLIP’s capabilities, this paper introduces a novel CLIP-based multimodal foreign object detection model tailored for railway applications, referred to as Railway-CLIP. This model leverages CLIP’s robust generalization capabilities to enhance performance in the context of catenary foreign object detection. The Railway-CLIP model is primarily composed of an image encoder and a text encoder. Initially, the Segment Anything Model (SAM) is employed to preprocess raw images, identifying candidate bounding boxes that may contain foreign objects. Both the original images and the detected candidate bounding boxes are subsequently fed into the image encoder to extract their respective visual features. In parallel, distinct prompt templates are crafted for both the original images and the candidate bounding boxes to serve as textual inputs. These prompts are then processed by the text encoder to derive textual features. The image and text encoders collaboratively project the multimodal features into a shared semantic space, facilitating the computation of similarity scores between visual and textual representations. The final detection results are determined based on these similarity scores, ensuring a robust and accurate identification of anomalous objects. Extensive experiments on our collected Railway Anomaly Dataset (RAD) demonstrate that the proposed Railway-CLIP outperforms previous state-of-the-art methods, achieving 97.25% AUROC and 92.66% F1-score, thereby validating the effectiveness and superiority of the proposed approach in real-world high-speed railway anomaly detection scenarios.
基金financially supported by the Central Government Guiding Local Science and Technology Development Fund of Henan Province(Z20241471091)the Independent R&D Funds of State Key Laboratory of Advanced Metallurgy(41624025).
