In high-altitude cold regions with long downhill lines, the friction braking system of high-speed trains is vulnerable to environmental disturbances and thermo-mechanical coupling, posing serious safety challenges. This study investigates the impact of snowy conditions on the tribological behavior of the braking interface. A scaled braking test rig was developed to simulate low-temperature snowy environments, and continuous drag braking tests were conducted under both room temperature (RT) and ice and snow (IS) conditions. Friction heat accumulation, friction coefficient evolution, wear morphology, and debris behavior were analyzed to clarify the governing factors of interfacial contact. The results show that IS condition markedly changed the thermal response and contact state of the friction pair. With rising temperature, the system shifts from ice-film lubrication to water-film lubrication and finally to dry friction. In the ice-film stage, the lubricating role of the ice film produces a much lower friction coefficient than under RT, while its heat absorption and dissipation capacities significantly suppress the temperature rise. As the ice melts, the interface becomes liquid-lubricated. The friction coefficient increases stepwise, lubrication remains unstable, and debris adhesion and re-entry intensify heat buildup, accelerating block temperature rise. Once the water film evaporates, dry friction dominates, with larger friction coefficient fluctuations and more severe furrow wear induced by sheared debris. This study improves understanding of braking interface evolution under snowy low temperatures and offers theoretical support for performance regulation and safety improvement in cold-region high-speed trains.

High-speed trains experience intensified temperature-wear coupling effects on long ramps, provoking friction-induced self-excited vibrations and compromising operation safety. Therefore, this study investigates the coupling characteristics of brake on long ramps and their influence on vibration signals through drag braking tests, finite element modeling, and a numerical simulation method proposed considering temperature and wear. Results demonstrate that temperature-wear coupling effects are markedly enhanced under long ramps, leading to nonlinear escalation of friction block wear. Rising temperatures amplify vibration signal intensity, while wear progression enlarges the contact area, significantly reduces contact stiffness, and diminishes vibration energy storage capacity. Coupling promotes wear-dominated energy dissipation, attenuating vibration intensity through synergistic interfacial dynamics.

A dragging friction experiment is conducted on a scaled brake dynamometer to simulate the long-ramp braking conditions of a high-speed train. A heavy thermal load is generated due to the long-term friction process, resulting in a high interfacial temperature of more than 480 degrees C. Friction heat is concentrated in the sliding region of the disc surface, where a significant temperature gradient is formed. The eccentric wear phenomenon is identified in the radial direction of the block surface. This differs from that under ordinary braking conditions, which produce relatively low temperatures; under ordinary parking braking conditions, for example, eccentric wear is found in the friction direction. Moreover, friction-induced vibration (FIV) is closely correlated with the interfacial temperature, and the vibration amplitude increases with increasing temperature, whereas the main frequency of FIV decreases as the temperature increases. For further exploration, a novel fully coupled thermo-mechanical-wear-FIV numerical method is proposed to simulate the temperature, wear, and FIV evolution of the brake process. This indicates that the numerical model can reproduce the tribological behavior of the brake system well, and the underlying mechanism of the eccentric wear phenomenon is explained. This numerical method can be used as an auxiliary tool to design or optimize brake systems in engineering.

A thermo-mechanical-wear finite-element model coupled with cohesive-zone method is proposed to simulate potential failure pattern of an aluminum-based composite brake disc under frictional thermal loads. The analysis reveals that during cooling, a pronounced axial stress mismatch develops at the composite/substrate interface near the inner ring, driving interfacial delamination. Damage initiates at localized high-stress sites and propagates circumferentially until arrest. Composite layer thickness is critical: an optimal AMMC layer thickness reduces thermal gradients and peak stresses, mitigating delamination, whereas excessive thickness is counterproductive. These findings highlight the role of interface stresses and layer design in preventing composite-layer failure under braking.

This paper introduces an innovative numerical method for analyzing the thermal-induced crack propagation of railway brake discs based on a fully coupled thermo-stress-wear approach. The method's reliability is confirmed through experimental validation of its thermal and wear predictions. Subsequently, the residual stress in the brake disc after braking is determined for crack propagation simulation. It is found that more concentrated temperature and stress distributions are obtained when wear is ignored. Moreover, material removal due to wear dissipates a portion of the frictional heat, leading to lower temperature and residual stress levels compared to scenarios without wear, which ultimately cause underestimation on the fatigue life of the brake disc. Therefore, interfacial wear is a highly influential factor regarding the propagation behavior and fatigue life of the thermalinduced crack of the railway brake disc.

Grasping the effective carrying capacity of airport hub subway stations in real-time serves as the foundation for enhancing the safety assurance capability of the hub. Starting from the perspectives of multiple subsystems, including people, stations, and trains, and combining passenger flow, system structure, and multiple attributes of trains, a system dynamics (SD) model for passenger travel in airport hub subway stations is established. The model is simulated using Vensim PLE 5.9d to analyze the effective carrying capacity of the transfer system under the existing configuration and layout of transfer facilities and equipment in the hub. The model features a modular architecture and interface, enabling quick and easy model establishment, and adapts to various configurations and operational characteristics of airport hub subway stations in a user-friendly manner. Multiple sensitivity simulation analysis experiments are designed to analyze changes in passenger flow density from multiple perspectives. This method can calculate the effective carrying capacity of airport hub subway stations, providing a scientific basis for planning, construction, and operational management. The effectiveness of the model is verified by analyzing the Pudong International Airport terminal subway station.

The local stability may dominate the design of a self-anchored suspension bridge with steel box girders. Due to geometric imperfections and welding residual stresses rarely considered for its ultimate bearing capacity analysis, the influences of the local buckling on the global structural behavior remain unknown. This paper presents a multi-scale finite element (FE) model for a self-anchored suspension bridge incorporating geometric imperfections and residual stresses in a steel box girder segment simulated by shell elements. Also, the pattern considering the defects in the shell FE model is validated by experiments. An extended parametric study is carried out via multi-scale FE models under various defects. Results illustrate that: ➀ the effects of local buckling on the ultimate bearing capacity of the bridge is small and can be ignored if geometric imperfections and residual stresses are not considered; ➁ the influences of local buckling becomes significant if geometric imperfections and residual stresses are included; and ➂ ultimate bearing capacity decreases with increase of defects, with geometric imperfection being the main factor influencing the ultimate bearing capacity of the bridge. Additionally, the thickness of steel plates has significant influences on the ultimate bearing capacity of the bridge. A comparison between the EN 1993–1-5 and the FE analysis results indicates that the former is conservative. This study provides useful insights for analyzing and designing local buckling from the perspective of steel bridge system.

Three triangular friction block configurations are commonly employed in high-speed train brake systems, namely, unperforated, perforated configuration with one circular hole, and perforated with three circular holes. In this study, we adopted these friction block types to investigate the effect of perforated friction block configurations on the brake performance of high-speed trains based on a self-developed brake test rig. The results indicate the significant impact of the number of the holes on the wear behavior, temperature distribution, and vibration characteristics of the brake interface. The friction surface of the unperforated block is covered by wear debris, while the perforated blocks produce less wear debris. Furthermore, the one-hole block exhibits a more uniform temperature distribution and better vibration behavior than that with three holes. The friction brake is a dynamic process, during which separation and attachment between the pad and disc alternatively occur, and the perforated structure on the friction block can both trap and expel the wear debris.

This paper presents a novel piezoelectric-triboelectric hybrid energy harvester, which includes two sub triboelectric energy harvesters (sub-TEHs) working under the alternative impacts between a swinging structure and two plates, and a sub piezoelectric energy harvester (sub-PEH) whose motion is coupled with the swinging structure through magnetic repulsion. With this design, 1:2 frequency-up conversion is achieved for both the triboelectric energy harvesting and piezoelectric energy harvesting because of the nature of swing motion. The introduced magnets also induce bistability with a dynamically tuneable potential barrier to the swinging structure, which improves its ability to get across the barrier to form interwell motion. Through experimental investigation, the frequency-up conversion effect is demonstrated. It also shows that this energy harvester can effectively operate in a broad bandwidth and exhibits good robustness. The practical applications of the energy harvester are also experimentally validated by testing its energy harvesting performance under water wave conditions, which performs well under such operating scenarios. Then, a theoretical model is established and its reliability is experimentally validated. Based on the model, the dynamic behaviours and energy harvesting performance of the energy harvester under different excitation parameters and system parameters are comprehensively investigated, showing that this device can effectively and broadly harvest energy from low-frequency ambient vibration.

The tribology behavior of the brake interface is a vital aspect since it determines the service life and operation safety of the train. To be more understanding about this, a fully coupled thermo-mechanical-wear finite element algorithm is proposed to study the evolution of temperature, wear and mechanical contact at the interface of high-speed train brake systems, and the correctness of which is experimentally validated. In this approach, contact stress is extracted to calculate the interfacial heat flux for the subsequent thermomechanical coupling analysis. Meanwhile, based on the Achard wear model, the interfacial wear degradation under thermal conditions is simulated through ABAQUS subroutine UMESHMOTION with the help of arbitrary Lagrangian-Eulerian (ALE) remeshing technique. Using the proposed method, the dynamic interaction between temperature, wear and contact stress is investigated, and the coupling mechanism between these factors is revealed. The results indicate that the temperature magnitude will be overestimated without considering the wear effect. In reverse, the thermal expansion has a significant influence on the wear and contact behavior. The interfacial contact behavior is jointly influenced by surface wear and thermal effects. Therefore, it is impossible to accurately predict the tribology behavior of the brake interface without a comprehensive consideration of these factors.

In this paper, a PZT (lead zirconate titanate)-based absorber and energy harvester (PAEH) is used for passive control of friction-induced stick-slip vibration in a friction system. Its stability condition coupled with PAEH is analytically derived, whose efficiency is then demonstrated by numerical simulation. The results show that the structural parameters of the PAEH can significantly affect the system stability, which increases with the mass ratio between the PAEH and the primary system, but first increases and then decreases with the natural frequency ratio between the PAEH and the primary system. The impacts of the electric parameters of the PAEH on the system stability are found to be insignificant. In addition, the PAEH can effectively suppress the stick-slip limit cycle magnitude in a wide working parameter range; however, it does not function well for friction systems in all the working conditions. The stick-slip vibration amplitude can be increased in the case of a large loading (normal) force. Finally, an experiment on a tribo-dynamometer validates the findings of the theoretical study, in which the vibration reduction and energy harvesting performance of the PAEH is fully demonstrated.

Dockless bike-sharing is becoming popular all over the world, and short-term spatiotemporal distribution forecasting on system state has been further enlarged due to its dynamic spatiotemporal characteristics. We employ a deep learning approach, named the convolutional long short-term memory network (conv-LSTM), to address the spatial dependences and temporal dependences. The spatiotemporal variables including number of bicycles in area, distribution uniformity, usage distribution, and time of day as a spatiotemporal sequence in which both the input and the prediction target are spatiotemporal 3D tensors within one end-to-end learning architecture. Experiments show that conv-LSTM outperforms LSTM on capturing spatiotemporal correlations.

When studying the deformation characteristic of tunnel lining in the expansive surrounding rock, most research focuses on the expansion effect of surrounding rock after water absorption, while seldom considers the softening effect caused by water absorption at the same time. Therefore, based on a failure case of a tunnel in expansive mudstone in northern China, this paper investigates the expansion characteristics of the mudstone and the deformation as well as the failure law of tunnel lining through laboratory tests, field monitoring and numerical simulations. The results show that the mudstone exhibits significant water disintegration and softening characteristics, with a noticeable deterioration in strength. The clay mineral content of the mudstone is 68.8 %, and evaluations of various indicators indicate moderate expansion potential. The failure modes at the crown of the preliminary lining are compressive failure, which are coincident with that of field monitoring. The expansion of the surrounding rock leads to a sharp increase in the internal forces of the preliminary lining, significantly weakening its safety and causing large deformation even damage. The maximum deformation of lining reached 449 mm, necessitating the dismantling and rebuilding of the damaged preliminary lining. Therefore, in the design and construction of tunnels in mudstone, considering the expansive potential is essential to ensure the safety of the project.

A novel two-degree-of-freedom hybrid piezoelectric-triboelectric energy harvester is proposed in this work, which consists of a pendulum oscillator whose 'tip mass' houses a piezoelectric cantilever beam that also forms two triboelectric sub-harvesters working in contact-separation mode. To broaden the bandwidth of the harvester, magnets are introduced to the system, bringing about bistability to both the pendulum and the cantilever beam. An electromechanical coupled theoretical model is established, based on which the vibro-impact dynamic behaviours of the energy harvester are investigated under various working conditions. Both experimental and numerical results indicate that, through this pendulum-based design, the energy harvester can achieve large-amplitude oscillation in a broad low-frequency band, which overcomes the difficulties of traditional bistable energy harvesters that interwell motion can't be achieved under low-frequency and weak excitations. It is found that the maximum outputs of the sub piezoelectric energy harvester and the sub triboelectric energy harvester are 0.93 mW and 0.053 mW, respectively, when the excitation frequency is 4 Hz and the excitation amplitude is 15 mm, which are 23 times and 38 times larger than the configuration without pendulum swinging. This research has provided a new effective solution to scavenge vibration energy from low-frequency and weak excitations.

???????????, ??????????????????????, ??????????????????????, ???????????????????????, ????????????, ???????????????????????????????, ?????????????????????, ???????????????????1. ?????????????????, ????????????????2. ?????????????, ???????????????????????, ???????????????????????, ???????????3. ??1000 MW??????, ????????????????, ???????????????????4. ?????, ?1000 MW????????????????????????????, ???????????????????1. ??????????, ??????????1000 MW????????????????????2. ??????????0.001?????, ???????????; ??????, ?????4250 W/(m2 center dot K)?155 W/(m2 center dot K), ?????96.35%; ??????????????????3. ????????, ??????????????????51.73%; ??, ?????????, ?????????????????, ?????????

In this paper, we take the suspension bridge of Oujiang Beikou bridge in Wenzhou, as the engineering background, the effects of a full rigid connection between segments, adding restraint cables between the stiffening beam and bridge tower, and adding restraint cables between the main cable and bridge tower, addition underwater auxiliary pier and the combination of the above measures on the natural vibration characteristics of the structure are studied and compared, especially the influence of torsional frequency and vibration mode. The calculation results show that when the hoisting quantity of stiffening beams is small, setting cables or a combination of the rigid connection of the beam and setting cables can improve the torsional frequency of the structure. When the hoisting quantity of stiffening beams is large, setting cables or combination setting auxiliary pier and rigid connection of beam

Multiple strokes are the main factors affecting the safe and stable operation of power equipment. As the core lightning protection equipment, arresters are also frequently thermally collapsed due to multiple strokes. This paper investigates thermal effects of polymer-housed metal-oxide surge arrester (PMOSA) under multiple strokes. The comparative experiments of PMOSA lightning impulse are carried out through multiple strokes of experiment platform, including continuous lightning stroke and multiple strokes. Furthermore, the temperature distribution of the housing surface is obtained by infrared imager for thermal effect analysis. Subsequently, some typical DC parameters are tested to explore the association of impulse aging and thermal effects of the arrester under multiple strokes. Finally, a thermal-electric coupling model (TECM) is constructed to investigate the influence of some factors on the temperature of PMOSA from the perspective of materials and structure. The research in this paper can provide a theory reference and brief data support for improving the heat dissipation performance of arresters under multiple strokes based on structural optimization design and material modification.

When urban rail transit is faced with a large number of commuter passengers during peak periods, passengers are often waiting for the next train because the subway is running at full load, which causes delays to the overall travel time of passengers. The calculation and prediction of the congestion delay in subway stations can guide the operation department and passengers to make better planning and selection. In this paper, we use a new method based on deep learning technology to evaluate the congestion delay of subway stations. Firstly, we use automatic fare collection (AFC) system data to evaluate the congestion delays of stations. Then, we use a convolutional long short-term memory (Conv-LSTM) network to extract spatial and temporal characteristics to solve the short-term prediction problem of the subway congestion delay in the network structure. The spatiotemporal variables include inbound passenger flow, outbound passenger flow, number of passengers delayed, and average delay time. As a spatiotemporal sequence, the input and prediction targets are both spatiotemporal three-dimensional tensors in the end-to-end training model. The effectiveness of the method is verified by a case study of the Chongqing Rail Transit. Experimental results show that Conv-LSTM is better than the benchmark models in capturing spatial and temporal correlation.

In this study, piezoelectric elements were added to a reciprocating friction test bench to harvest friction-induced vibration energy. Parameters such as vibration acceleration, noise, and voltage signals of the system were measured and analyzed. The results show that the piezoelectric elements can not only collect vibration energy but also suppress friction-induced vibration noise (FIVN). Additionally, the wear of the friction interface was examined via optical microscopy (OM), scanning electron microscopy (SEM), and white-light interferometry (WLI). The results show that the surface wear state improved because of the reduction of FIVN. In order to analyze the experimental results in detail and explain them reasonably, the experimental phenomena were simulated numerically. Moreover, a simplified two-degree-of-freedom numerical model including the original system and the piezoelectric system was established to qualitatively describe the effects, dynamics, and tribological behaviors of the added piezoelectric elements to the original system.