Due to their exceptional wave manipulation characteristics, acoustic metastructures have attracted substantial attention in vehicle noise, vibration, and harshness (NVH). However, the further development and application of passive acoustic metastructures are limited by the narrow and non-tunable low-frequency bandgaps and bandwidth. To address this challenge, an electrically controlled acoustic metastructure was proposed to enable flexible bandgap tuning, and the corresponding electrical twin theory was established. According to the classical electromechanical analogy, a two-dimensional electrical twin circuit for a Kirchhoff-Love thin plate was established by the finite difference method. Then, an inductance-capacitance-resistance (LCR) resonant circuit was connected in series to form the twin circuit of a metastructure unit, with a tunable capacitor introduced to achieve electrical bandgap tuning. Finally, a spiral-shaped electrically controlled metastructure was derived from the twin circuit and verified through simulations and experiments. The results confirm that the twin circuit constitutes an exact electrical-domain mapping of the metastructure. The equivalent stiffness of the metastructure can be adjusted by the electrical control, thereby facilitating bandgap tuning. The resulting tuning law can be efficiently predicted and analyzed by the twin circuit. The designed spiral-shaped electrically controlled metastructure exhibits a significant order-tracking noise reduction effect for electric seats, with an average sound pressure level reduction of approximately 7.4 dB(A) in the wide frequency range of 200–460 Hz. The proposed twin circuit contributes to the electromechanical integrated design of electrically controlled metastructures, and it provides a theoretical paradigm for the study of different types of electrically controlled metastructures.

To address the inadequate anti-roll stiffness of the axle box in-board bogies of high-speed electric multiple units (EMUs), a primary suspension configuration was proposed to replace the traditional hydraulic damper with hydraulic interconnected units. The configuration could increase the anti-roll stiffness without increasing the vertical stiffness. Firstly, the equilibrium equations of oil pressure, flow rate, and output force were derived. A nonlinear dynamic model of the vehicle system was established using SIMPACK, and a simulation model of the hydraulic interconnected units was created in MATLAB/Simulink to facilitate co-simulation of the vehicle-hydraulic interconnected unit coupling system. Subsequently, the accuracy of the simulation model was validated based on the quasi-static characteristic test of the hydraulic interconnected units and the dynamic tests of the roller rig of the entire vehicle. The simulation analysis was conducted to ascertain the impact of pivotal parameters associated with the hydraulic interconnected units on the roll angle of the car body, derailment coefficient, and riding index for various operation conditions of vehicles. Finally, the field dynamic tests were conducted to verify the improvement in the dynamic performance of vehicles during curve negotiation. The results have shown that the roll stiffness of the interconnection unit is significantly greater than that of the traditional hydraulic dampers. The roll angle of the car body can be reduced by more than 0.5°, which is conducive to narrowing the dynamic limit and ensuring overturning safety. The field test results demonstrate that the dynamic indexes of hydraulic interconnected units are comparable to those of traditional oil pressure dampers. It is viable to address the issue of inadequate anti-roll capability of axle box in-board bogies by adopting hydraulic interconnected units.

To investigate the influence of the dynamic braking process of high-speed trains on the longitudinal force at the pier tops of simply supported beam bridges, the rail-level braking force time-history curve was first calculated and obtained via multibody system dynamics simulation. Longitudinal resistance tests were then conducted on WJ-8 type low-resistance fasteners to reveal the law governing the influence of loading frequency and vertical load on the longitudinal resistance properties of the fasteners. Finally, a finite element model for longitudinal track–bridge interaction in multi-span simply-supported girder bridges was established. In this model, the wheel’s vertical and longitudinal forces were applied as moving concentrated loads on the rail, taking into account the uneven distribution of dynamic vertical force among the fasteners and their corresponding vertical-load-dependent longitudinal resistances. The influence of braking stop position and number of spans on the dynamic response of the track–bridge system was analyzed using the dynamic time-history method, and the results were compared with those from static analysis. The findings indicate that the longitudinal resistance of the fasteners is not significantly influenced by the loading frequency but is sensitive to the vertical load they carry. The longitudinal forces in the rail and at the pier tops are maximized when the train stops braking at the abutment of the final span. While these forces increase with the number of spans, they stabilize beyond eight spans. A discrepancy is observed between the dynamic and static analysis results for the maximum rail stress and displacement, yielding a dynamic amplification factor of approximately 1.05. Furthermore, the dynamic amplification factor is about 1.07 for the pier experiencing the greatest braking force, but can reach up to 1.93 for piers subjected to smaller forces.

To address the two types of rail corrugation in small radius curves of the Chongqing metro (short-wavelength corrugation on inner rails in the sections without rail gaps, and long and short-wavelength corrugation on inner rails in the sections with rail gaps), the comparative study on the causes of two types of rail corrugation was conducted based on the theory of wheel-rail frictional coupling vibration. The finite element models of the wheel-rail systems in the section with and without rail gaps in small radius curves were established, and their stabilities were investigated using the complex eigenvalue analysis method. Then, the dynamic response of the wheel-rail system under the effects of rail gap and rail corrugation irregularities was investigated using the transient dynamic analysis method. The results have shown that the wheel-rail system exhibits frictional self-excited vibration in both sections with and without rail gaps on small-radius curves, with main frequencies of 479.26 Hz and 477.65 Hz, respectively, which can induce short-wavelength corrugation from 30 to 40 mm. Rail surface irregularities increase the dynamic response of the wheel-rail system. The induced feedback vibration has a main frequency of 112.79 Hz, thus inducing long-wavelength corrugation from 150 to 160 mm. The feedback vibration induced by short-wavelength corrugation irregularities only serves to increase the depth of the short-wavelength corrugation itself and does not induce corrugation with a new wavelength.

To investigate the thermal characteristics inside the control and protection cabinet of nuclear safety-class instrumentation and control (I&C) systems and the variation patterns of the steady-state temperature (SST) of key chips (CPU and field programmable gate array (FPGA)), experimental studies were conducted on the cabinet under different ambient temperatures. The finite element method was employed to simulate the experimental process, and the accuracy of the numerical model was validated by comparing the experimental results. Furthermore, the SST values of CPU and FPGA under 100 sets of random working conditions were calculated by the finite element model, and the SST values of CPU and FPGA under different working conditions were learned and predicted using four algorithms of multi-output support vector regression (M-SVR), extreme gradient boosting (XGBoost), artificial neural network (ANN), and Bayesian ridge regression (BRR). Results show that when the ambient temperature is 20 ℃, the SST of CPU and FPGA is 37.5 ℃ and 33.5 ℃, respectively. When the ambient temperature is 55 ℃, the SST of the CPU and FPGA rises to 72 ℃ and 68 ℃, respectively. Finite element analysis can well simulate the test phenomenon, and the calculated chip SSTs are in good agreement with the experimental results. All the four algorithm models can be used to predict chip SST, among which the ANN algorithm exhibits the best prediction performance on the test set. It has a mean squared error (MSE) less than 0.15% and an R ²value greater than 0.99 and exhibits the strongest generalization ability. In contrast, although the other three models show good prediction performance for samples with high SSTs, the prediction error for samples with low SSTs is large, especially for the XGBoost model, whose prediction error is as high as 3.65 ℃. The research provides a new method for SST prediction of chips in nuclear safety-class control systems.

Morphological filtering (MF) is an effective method for bearing fault diagnosis with the capacity of recovering transient impulse features from noisy vibration signals, in which the choice of shape and length of structural element has an important impact on MF performance. To solve this problem, an enhanced time-varying structural element (ETVSE) based on median filtering was proposed to more accurately match and extract periodic transient features hidden in noisy signals. Moreover, the power spectrum (i.e., the frequency spectrum of autocorrelation signal) was applied to the filtered signal to further enhance fault-related components and eliminate broadband noise pollution. Finally, a bearing fault diagnosis method called enhanced time-varying morphological filtering (ETVMF) was developed, which combined the advantages of ETVSE and power spectrum. The analysis results of simulated data and measured data of two railway axle-box bearing test rigs show that, compared with the compared method, ETVMF demonstrates superior fault feature extraction performance and can accurately identify bearing inner race, outer race, and rolling element faults under complex noise interference, while obtaining higher performance quantification index and lower calculation cost.

The problem of vibration and noise caused by train operation is increasingly prominent, and it is difficult for traditional tuned mass damper (TMD) to achieve lightweight and broadband vibration reduction for rail. In view of this, inertial amplification mechanism (IAM) was introduced to achieve greater effective working quality of TMD by using inerter, so as to enhance the suppression of rail structure vibration. A new method for solving the complex band characteristics was proposed by using the energy method and the virtual spring method, based on which the complex band analysis model of the rail structure configured with IAM-TMD was established, and the accuracy of the model was verified with the solving results of the finite element method (FEM). On this basis, the influence mechanism of IAM on the vibration reduction effect of traditional rail TMD was investigated by taking the complex band characteristics as the evaluation index, and the modulation effects of IAM mass ratio, lever angle, and damping coefficient on the propagation of vibration wave in the rail structure were analyzed. The results show that the imaginary part of the complex band can describe the attenuation process of wave propagation inside the bandgap well. After the application of the IAM with α = 0.05 and θ = 10°, the original Bragg bandgap under TMD is widened from 925— 1260 Hz to 881— 1320 Hz, and the imaginary part of the complex band is increased, which implies that the attenuation capability of TMD is enhanced. The vibration reduction effect of IAM-TMD is proportional to the mass ratio and damping coefficient, and inversely proportional to the lever angle. The complex band characteristics are utilized to analyze the IAM, and the research results can provide a new idea for rail vibration reduction.

Micro-pressure waves are generated and noise is induced when the initial compression wave generated during the entry of a high-speed metro train into a tunnel propagates to the tunnel exit. In some cases, sonic booms may also occur, resulting in serious environmental problems for residents. To effectively control the micro-pressure wave noise at tunnel exits, numerical simulation studies on the acoustic characteristics of micro-pressure wave noise were conducted, and an acoustic suppression structure targeting low-frequency micro-pressure wave noise was proposed. Firstly, large eddy simulation (LES) was employed to obtain near-field unsteady flow field data at the tunnel exit, using the Ffowcs Williams-Hawkings (FW-H) acoustic analogy to predict the type of micro-pressure wave noise sources. Secondly, based on the unsteady flow field data, the acoustic finite element method (AFEM) was utilized to compute the far-field radiation of micro-pressure wave noise and analyze the mitigating effect of acoustic structures of the tunnel exit on micro-pressure wave noise. Finally, the accuracy of the numerical methods was validated through a moving model test. The results indicate that at a train speed of 160 km/h, dipole noise predominates in the micro-pressure wave noise at the tunnel exit. Dipole noise radiates outward in a semi-ellipsoidal shape, with its energy mainly concentrated below 20 Hz and a peak frequency being 4 Hz. The attenuation of dipole noise in the tunnel exit direction follows an exponential decay law. Adding acoustic structures at the tunnel exit significantly reduces micro-pressure wave noise. Specifically, the sound pressure levels (SPLs) outside the tunnel exit across various longitudinal planes decrease by approximately 3 dB. At the designated measurement points, located at 20 m and 50 m, the SPLs are reduced by 3.54 dB and 2.62 dB, respectively.

To address the tendency of spectral segmentation boundaries concentrating on local narrow bands when the empirical Fourier decomposition (EFD) method was applied to bearing fault signals, an order statistics filter (OSF) was used to simplify the frequency spectrum of the acquired bearing vibration signal, and then averaging and sliding processing and pre-segmentation were performed. To address the potential problem of excessive decomposition, a boundary fusion algorithm based on the frequency-domain squared Gini index (FDSGI) was proposed to adaptively determine segmentation boundaries and decomposition modes. The envelope spectrum harmonic significance (ESHS) indicator was used to select the optimal components. Further, bearing fault diagnosis was enabled through envelope spectrum analysis of the optimal components. The comparative test of bearing fault simulation signals and experimental signals demonstrates that empirical Fourier decomposition based on spectrum reconstruction (SREFD) outperforms EFD and empirical wavelet transform (EWT) in terms of spectral segmentation accuracy. The processed signals allow for clearer observation of bearing fault characteristic frequencies and their harmonics, which validates the effectiveness and robustness of the proposed method.

To address the issues of repeated decoding and resource waste caused by random batch generation of the outer code in existing outer code block coding schemes for batched sparse (BATS) codes, the optimization of theoretical batch count and dynamic adaptability of BATS codes was systematically investigated based on the outer code block encoding scheme. First, under the condition of a known packet loss rate, a batch consumption analysis model for BATS codes was established, and an optimal degree value computation method was derived to tackle the challenges in existing schemes regarding theoretical batch count calculation and optimal degree value determination for minimizing batch count consumption. Second, for scenarios with unknown packet loss rates in the channel, a reinforcement learning-based dynamic degree optimization method for BATS codes was proposed, enabling real-time acquisition of degree values through an intelligent learning mechanism. Finally, simulation experiments were conducted to evaluate the theoretical model and the proposed dynamic optimization method. Simulation results have shown that the established transmission model based on outer code blocks and its batch count computation formula can be used to calculate batch consumption and determine the optimal degree distribution. Simulation results demonstrate that the proposed reinforcement learning-based optimization scheme achieves lower average batch count consumption than fixed-degree value schemes with unknown packet loss rates and maintains great performance in dynamic channel environments.

Currently, most Min-Zhe timber arch lounge bridges suffer from the lack of detailed blueprint documentation, leading to unsatisfactory preservation effects and insufficient research on fire spread patterns and disaster prevention. To solve these problems, a digital reconstruction technology based on three-dimensional scanning and BIM parameterization was proposed to construct the digital twins of timber arch lounge bridges, and a BIM-fire dynamics simulator (FDS) was used to analyze the fire spread patterns and fire prevention strategies of such bridges. Firstly, the original point cloud model of Helong Bridge was obtained through on-site three-dimensional scanning, and after registration, denoising, and thinning processes, a BIM parametric digital twin was established to calculate its fire load density. Secondly, the IFC format was adopted to realize the interaction between BIM and FDS, and the fire digital twin of the timber arch lounge bridge was established. Simulation analysis was conducted through parameters such as heat release rate (HRR), fire spread phenomenon, visibility, temperature, and harmful gas concentration, and the fire spread patterns were derived by simulating and analyzing multiple typical fire source scenarios in FDS. Finally, fire prevention optimization strategies such as material flame-retardant treatment, bridge deck non-combustible transformation, and sprinkler system layout were discussed. The research results indicate that the fire load density of the timber arch lounge bridge is as high as 4 017.764 MJ/m², far exceeding that of typical Chinese and foreign buildings, thus posing an extremely high fire risk. Among multiple typical fire source scenarios, excluding HRR mutation values, the HRR peaks of the arch structure and bridge bottom working conditions are stable at 100 MW and 95 MW, respectively. The HRR peaks of the bridge center and bridge head working conditions are stable at 88 MW and 70 MW, respectively. The HRR of the bridge side bottom and bridge top working conditions does not reach the peak within 1 000 seconds, with maximum values of 55 MW and 22 MW. Therefore, the fire risk of ignition under the bridge is the highest, followed by ignition on the bridge deck, while the fire risks of roof ignition and ignition at the bridge side bottom are relatively low. Through fire simulation and quantitative analysis of multiple fire parameters, it is confirmed that the three fire prevention measures can delay the fire spread of timber arch lounge bridges, and the upper and lower fire compartments, wood flame retardancy, and sprinkler systems reduce the HRR peak by 23 MW, 39 MW, and 63 MW, respectively. The research results can serve as the basis for information storage, quantitative analysis of fire spread, and preventive protection of timber arch lounge bridges and provide technical support for the long-term safe operation and maintenance of cultural heritage buildings.

Due to the unique structural form of stone masonry walls in traditional Tibetan architecture, the complexity of the material composition, and the interference of environmental factors, the accurate detection of hidden damage in the wall is extremely challenging. To address the limitations of traditional methods in target signal identification, experimental data obtained from ground-penetrating radar (GPR) testing of Tibetan stone masonry walls were used to verify the reliability of the numerical simulation results. Then, the propagation characteristics of the effective wave were systematically analyzed, with the focus on the effects of different GPR antenna center frequencies, GPR spacing from the wall, and crack width on the echo characteristics. Finally, the successive variational mode decomposition (SVMD) method was applied for signal decomposition and reconstruction. Its stability, applicability in target signal identification, and its advantages over existing techniques were evaluated across varying noise levels and crack widths. The results have shown that when the SVMD method is applied to the noise reduction of GPR signals in masonry walls of traditional Tibetan architecture under specific conditions, it improves the signal-to-noise ratio by 58.36% and 18.67% compared to the empirical mode decomposition (EMD) and variational mode decomposition (VMD) methods, respectively. It can effectively separate the target signals, background wall signals, and noise signals, providing reliable technical support for extracting damage characteristics in masonry walls of traditional Tibetan architecture.

To improve the cohesiveness of foam asphalt cold recycled binder (composed of cement, old asphalt, and foam asphalt), three modifiers of foam asphalt cold recycled binder, including polyphosphoric acid (PPA), polymerized styrene butadiene rubber (SBR), and triglyceride (TG) were selected, and molecular models of foam asphalt cold recycled binder with different modifiers and their dosage were established by molecular dynamics simulation method. The effect of different modifiers and their dosage on the improvement of the interface properties of foam asphalt cold recycled binder was studied based on interface energy, interaction energy, diffusion coefficient, and radial distribution function (RDF) of water molecules. The significance difference of each index and the weight of the modification scheme were discussed by significance tests and the analytic hierarchy process. The results have shown that the addition of 0.8% PPA has the most significant effect on the cohesiveness of the foam asphalt cold recycled binder, which can effectively improve the interfacial energy, free volume, and water damage of the foam asphalt cold recycled binder, and also make the foam asphalt cold recycled binder have better diffusion ability. The addition of 15.0% TG can improve the interaction effect of the foam asphalt cold recycled binder, but the diffusion ability is poor. The addition of 2.0% SBR has the best effect on the water damage resistance of foam asphalt cold recycled binder, but the overall modification effect of SBR is not so good. There is no significant influence among different dosages of modifiers, and each modification scheme is independent and has its own advantages. After comprehensive comparisons, 0.8% PPA has the best effect on improving the interfacial cohesiveness of foam asphalt cold recycled binder.

The conservation of ancient stone arch bridges is severely hindered by drawing deficiency, difficult on-site survey and structural deterioration. These obstacles make it difficult to acquire the geometric parameters required for refined mechanical models and to reproduce the real damage state of individual blocks, so that reliable finite-element (FE) models can hardly be established. To solve the problem, a modeling strategy of ancient stone arch bridges based on masonry structure gap image recognition is proposed. First, a comprehensive dataset with labeled contours of masonry blocks in stone arch bridges was constructed, which was used to train a YOLOv8 convolutional neural network for instance segmentation of the masonry block contours on the bridge images. The trained network attained an accuracy of 96.51 %, a recall of 92.89 % and an F1-score of 0.94 on the contour recognition task. Second, the segmentation results were post-processed with the Douglas–Peucker algorithm and related techniques to extract key geometric information of individual blocks. Finally, a parametric modelling procedure was developed: an ABAQUS Python script was developed to automatically generate a separate FE model that faithfully replicate the actual masonry construction, with contact interfaces defined between blocks for subsequent mechanical simulation. The study shows that under self-weight and deck loads the peak principal stress in the arch rib predicted by the separate model is about 1.2 times that given by a conventional monolithic model, and conspicuous stress concentrations appear at masonry defects. The separate model can more accurately reproduce the masonry block distribution and local defects of the actual bridge, which has significant advantages for revealing the damage mechanism of the masonry structure of the ancient bridge, and provides a new perspective and method for the mechanical simulation study of the protection of ancient bridges.

The pile-net composite foundation can effectively reduce the post-construction settlement in road engineering, and has often been used for ground improvement for runway and apron systems in the airfield of coastal airports in China recently. However, the available research on the pile-net composite foundation is mostly focused on the bearing characteristics before construction, lacking research to quantitatively evaluate the influence of aircraft taxiing loads on the bearing characteristics of the pile-net composite foundation in the runway. Therefore, the parameters such as the thickness of the fill layer, the spacing between piles, and the type of aircraft were changed. In addition, based on the dynamic load influence coefficient, the differential settlement ratio after construction, and the degradation coefficient of soil arch, the finite element software ABAQUS was used, and a numerical analysis of the mechanical deformation characteristics of the pile-net composite foundation in the runway under the influence of aircraft taxiing load was conducted. The influence of aircraft taxiing load on the bearing and settlement characteristics of the pile-net composite foundation in the runway was quantified. The results show that when the thickness of the fill layer decreases from 4.5 m to 1.5 m, the soil arching effect is weakened by about 3.3% to 15.1%. When the spacing between piles decreases from 6 d to 3 d , the soil arching effect is weakened by about 7.8% to 12.0%. The differential settlement ratio after construction at the location of the soft soil layer may exceed the recommended value of the code. As the fill layer becomes thinner, the pile spacing and aircraft weight are greater; the main gear load is more concentrated, and the soil arching effect becomes weaker.

The middle and rear axles of three-axle mining dump trucks are the main load-bearing axles, and their output characteristics influence the driving stability of the vehicles. To solve the load-bearing problem of mining dump trucks and improve the driving stability of the vehicles at the same time, a kind of hydraulically interconnected suspension was proposed. The impedance transfer matrix method was adopted to derive the flow-pressure relationship of the suspension, and the 1/2 vehicle mechanical-hydraulic coupling equation was obtained. The complete decoupling of body-wheel motion modes was realized by solving the system state matrix. Finally, the road obstacle experiment was carried out to investigate the operational characteristics of the suspension. The analysis results show that the suspension system reduces the natural frequency of body bounce motion, increases the damping ratio, attenuates the body bounce vibration quickly, and improves the dynamic load distribution of the middle and rear wheels. When the vehicle passes a 120 mm high triangular road obstacle at the speed of 15 km/h, the maximum pressure difference between the two oil cylinders of the hydraulically interconnected suspension is 1.15 MPa, and the maximum response time is 0.3 s. These are good to achieve uniform load. At the same time, the displacement of the two oil cylinders is basically equal, but the direction is opposite, which plays a good role of displacement compensation and helps to maintain the attitude of the body during travel.

To make route guidance strategies more targeted for enhancing efficiency and practability, a route guidance model based on a multi-layer network and vehicle-source information of the regional highway was proposed. Firstly, a multi-layer network of the regional highway was constructed based on the complex network theory. The congested segments in the highway network were identified, and their vehicle sources were located and clustered. The locations for distributing route guidance information were further determined. Next, the travel cost function was controlled by applying the social welfare coefficient. A route guidance model with a variable parameter was established for balancing individual and social benefits. Finally, a route guidance information release framework was constructed, and the influence of the proportion of travelers using the guided routes on the system was investigated when the route guidance scheme was implemented. The results have shown that the proposed model guides a few travelers, and their average travel time increases by 2.1 minutes, while the average travel time of all travelers decreases by 9.1 minutes. The generated route guidance scheme poses a small adverse impact on the travelers, effectively decreases the total time spent when considering the fairness, and provides a more efficient and feasible strategy for alleviating highway congestion.

To reduce the phenomenon in which China-Europe Railway Express operators compete for cargo sources by offering excessively low prices, an asymmetric tripartite evolutionary game model of “government-operator-supplier” was constructed under the reward-and-punishment mechanism of the government. The model was based on local government subsidies to China-Europe Railway Express operators and suppliers and took into account the actual conditions in the operation process of China-Europe Railway Express. Through numerical simulation, the influence of the main factors, including the reward and punishment of the government, on the evolutionary stability strategy of the system was analyzed, providing theoretical references for the coordinated development of the China-Europe Railway Express accordingly. The results have shown that the increased government punishment will effectively promote synergistic development between operators and suppliers. Differential subsidies are given according to the different strategies of operators and suppliers. As the difference between different subsidy levels becomes larger, it is more beneficial for synergistic development. Reasonable setting of the maximum subsidy per unit of container provided by the government to operators, and gradually reducing the amount until the subsidy is completely withdrawn, is an effective way to promote synergistic development. The additional social benefits of the government are a positive influence in determining the choice of government strategies.

The dynamic load distribution and stiffness characteristics of bearings are important factors that cause vibration and cutting stability of machine tools. On the basis of nonlinear elastic Hertz contact theory and Jones-Harris model, combined with the judgment criterion of roller–raceway contact state, a five-degree-of-freedom analysis model of multi-row combined ball bearings was proposed to compare dynamic load distribution and dynamic stiffness characteristics of left and right rows in tandem back-to-back (TBT) combined ball bearings under different operating conditions. The improved iterative algorithm was adopted for solution, which greatly improved the convergence of the iterative calculation under the fluctuation of different external conditions and yielded the dynamic load distribution and dynamic stiffness characteristics within the TBT combined bearings under constant preload. The results show that the rotational speed, radial load, and axial load can change the load distribution and dynamic stiffness characteristics of combined bearings, and have different effects on the left-row and right-row bearings. The increase in rotational speed can lead to the incomplete contact area within the bearings, which makes the load distribution of the bearing oscillate. Compared with that of a single bearing under equivalent external load conditions, the radial dynamic stiffness of the combined bearing is more significantly improved than the axial dynamic stiffness.

Ultra-high ductile concrete (UHDC) has excellent strain hardening and multi-cracking characteristics, and it has great potential in impact load resistance. Direct tensile tests were conducted under 11 strain rates (0.000 1– 189.0700 s⁻¹) ranging from quasi-static to impact states to investigate the strain rate effect on the tensile properties of UHDC. The influence of strain rate on the shape of the tensile stress–strain curves, cracking pattern, and tensile performance indicators of UHDC was analyzed. The expression of the dynamic increase factor of tensile performance indicators regarding strain rate was established. In addition, the influence of the tensile rate on the fiber–matrix interface bonding performance was analyzed to further explain the strain rate effect on the tensile properties of UHDC. The results show that the deformation capacity of UHDC decreases with the increase in strain rate. When the strain rate is 102.000 0 s⁻¹, UHDC still has significant strain hardening and multi-cracking pattern capacity, with the tensile strain capacity up to 4%. The average crack width, which keeps a constant value of 100 μm, does not vary with the strain rate change, exhibiting the excellent crack control capacity of UHDC. The relationship curves between the dynamic increase factor of the tensile performance indicators and strain rate show a clear two-stage characteristic.

Efficient geographic and geological knowledge services for railway engineering form a crucial foundation for supporting the multi-scale and multi-disciplinary intelligent applications of digital twin technology in railways. To improve the completeness of query results and enhance the capability for integrated analysis across the multi-scale “region–engineering project–construction site” applications of railway digital twins, a meta-network model for the dynamic distribution of geographic and geological knowledge was proposed. This model was designed as a distributed knowledge base network system, with railway agents, business departments, knowledge relationships, and multi-scale application scenarios as key nodes. A meta-network disruption algorithm for distribution optimization was implemented, with node importance assessed using degree centrality indicators. By analyzing the distribution influence through network perturbation, the influence range of nodes was calculated, obtaining the optimized distribution structure of the knowledge base. To validate this approach, it was applied to optimize the distribution of the knowledge base within the knowledge base management and application scenario for railway digital twins of a major railway bridge project. Experimental results show that, when processing knowledge retrieval tasks at the engineering and regional scales, the distribution optimization method increases the number of query results with reduced retrieval time and enhanced result matching accuracy.

To investigate the complex nonlinear behavior of parabolic two-hinged arches subjected to a midspan concentrated force, a theoretical method was proposed to reveal its rule. Based on the nonlinear strain–displacement relationship of arches in the Cartesian right-angled coordinate system, nonlinear equilibrium differential equations of parabolic two-hinged arches subjected to a midspan concentrated force were derived, as well as the corresponding high-precision approximate analytical solutions of these nonlinear equations. The common rules of complex nonlinear behavior of parabolic two-hinged arches subjected to a midspan concentrated force were investigated by the limitation analysis of these high-precision approximate analytical solutions in discontinuous points: 1) If and only if the modified slenderness ratio is greater than or equal to the limit-pattern critical slenderness ratio, limit-pattern nonlinear behavior occurs in parabolic two-hinged arches subjected to a midspan concentrated force. Moreover, multiple extreme points appear on the limit-pattern nonlinear equilibrium path, and the number of extreme points is positively correlated with the parameter k . 2) When limit-pattern nonlinear behavior occurs in parabolic two-hinged arches subjected to a midspan concentrated force, the limit-pattern nonlinear equilibrium path passes through specific points. The coordinates of these points are fixed and do not change with variations in the modified slenderness ratio. 3) If and only if the modified slenderness ratio is greater than or equal to the bifurcation-pattern critical slenderness ratio, bifurcation-pattern nonlinear behavior occurs in parabolic two-hinged arches subjected to a midspan concentrated force. This bifurcation-pattern nonlinear behavior exhibits multiple equilibrium paths. Comparisons against nonlinear finite element results demonstrate that the proposed approximate analytical solutions of nonlinear equilibrium of parabolic two-hinged arches subjected to a vertical midspan concentrated force have sufficient accuracy, and the rules of complex nonlinear behavior of parabolic two-hinged arches subjected to a midspan concentrated force agree well with nonlinear finite element results. The maximum relative error is 9.05%, which meets the needs of engineering accuracy.

As demands for manufacturing quality and production efficiency continue to rise in modern industry, tool wear has emerged as a critical constraint affecting surface roughness. Traditional tool condition monitoring and process parameter optimization methods are often based on empirical models or static optimization strategies, limiting their adaptability to complex, dynamically changing, multivariable environments. In response, this study proposes an innovative approach integrating multi-scale distribution ratio (MSDR) with Bayesian multi-armed bandit (BMAB) for process parameter online optimization, incorporating real-time tool condition data into the optimization framework. Additionally, by combining Bayesian optimization and multi-armed bandit strategies, this method enables real-time adjustments to process parameters in dynamic manufacturing environments, effectively balancing exploration and exploitation to maximize machining efficiency. Compared to mainstream methods, MSDR demonstrates exceptional precision and stability in tool condition monitoring, achieving MAE, SMER, and RMSE values of 0.145, 0.258, and 0.194, respectively. BMAB also performs exceptionally in optimizing cutting efficiency and computational effectiveness, achieving 2305 mm³/min and a runtime of 2.92 seconds, respectively. Therefore, tool state-aware online optimization of process parameters presents a novel and promising technical pathway for high-precision manufacturing.

To address the prevalent issues of low effective throughput and limited covertness in high-speed rail (HSR) wireless communication systems, an optimization problem was formulated to maximize the system’s effective throughput, subject to constraints on the covert requirement, transmit power of the maximum artificial noise (AN), and the unit modulus of the intelligent reflecting surface (IRS) phase shifts, and a beamforming method for covert HSR wireless communications based on IRS assistance and AN enhancement was designed. An alternating optimization strategy was adopted, decomposing the coupled optimization variables into three subproblems, including base station beamforming, IRS phase shift optimization, and AN transmit power optimization. The covert requirement constraint was mapped onto a complex circle manifold using the quadratic transform method from fractional programming. The conjugate gradient (CG) algorithm was employed to optimize the IRS phase shifts. The Dinkelbach algorithm was used to design the AN transmit power, and these steps were iterated alternately. Simulation results demonstrate that the proposed algorithm achieves a lower computational complexity. Under high-speed scenarios, it enhances the system’s effective throughput by 27.31% and improves the covert transmission performance, which is important for enhancing the security of information transmission in HSR wireless communication systems.

To address the issue that the asymmetric basic type calculation model, which the intersection method relies on in highway alignment design, fails to perform calculations when turning curves include incomplete transition curves, the asymmetric basic type calculation model was used as the foundation. By analyzing the causes of the model’s failure in solving incomplete transition curve scenarios, the structure and solution logic of the calculation model were optimized and improved, and an asymmetric general type calculation model was further proposed. This new model introduced a novel definition of transition curve direction. It classified transition curves into two categories, positive and negative, by judging the relationship between the curvature change trend of the transition curve and the route’s traveling direction. Then, based on the positional order of the transition curve within a single curve, a special local coordinate system was established. Through geometric derivation, the tangential growth value and curve offset value of the incomplete transition curve were obtained, enabling the subsequent use of the asymmetric basic type calculation model for further solution. The research has shown that the asymmetric general type calculation model eliminates the restrictions of the asymmetric basic type model on alignment combination types, allowing the curvature radii at the start and end points of transition curves to be arbitrary values. By comparing the calculation results of the same complex curve segment with those obtained using the traditional element method, the differences in the calculated mileage values and coordinates of the control stakes are both less than 1 mm, which meets the engineering accuracy requirements.

To address the power frequency overvoltage and high costs caused by cable applications in high-voltage dedicated line continuous power supply systems, an optimized hybrid line configuration scheme was proposed. First, a no-load equivalent circuit model was established using two-port network theory, and the distribution laws of voltage and no-load circulating currents along the hybrid lines were theoretically derived by incorporating the distributed parameters of the lines. Second, a π-type equivalent circuit of the system was constructed through port equivalence, and a unified multi-load power flow model was developed using a network splitting algorithm. A calculation method for system equivalent impedance and the traction network’s maximum supply distance was proposed to quantitatively evaluate the power supply capability of hybrid lines. Furthermore, to minimize the total life cycle cost, the proportion of cable and overhead line installations was optimized. Simulation results demonstrate that the “cable + overhead line” scheme effectively suppresses power frequency overvoltage, reduces no-load current to one-third of that in pure cable configurations, and retains the long-distance supply advantage of cables (maximum supply distance of 95 km), saving approximately 5.1 million yuan in investment compared to conventional schemes.

The interaction between natural disasters forms a complex disaster chain, making the losses caused by composite disasters more severe. To quantify the risk of disasters caused by complex disaster chains, explore the vulnerability level of regions to complex disaster chains, and effectively promote disaster risk prevention work, the triggering and superposition (reduction) effects of disaster chains were considered. A vulnerability assessment index system for composite disaster systems was constructed from three dimensions: exposure of disaster-bearing bodies, susceptibility, and adaptability of disaster-prone environments. A series of models for assessing the exposure degree of composite disaster-bearing bodies, disaster-prone environmental sensitivity, and adaptability was established through derivation. Subsequently, they were weighted to obtain a series of vulnerability assessment models for composite disaster systems. By taking the rainstorm-landslide disaster chain in the Guangdong−Hong Kong−Macao Greater Bay Area as an example, the vulnerability index of rainstorm, landslide, and rainstorm-landslide disaster chain in the Greater Bay Area was calculated by combining convolutional neural network （CNN）, coupling model of a parameter optimal geographical detector and analytic hierarchy process （OPGD-AHP）, sequence relation method–technique for order preference by similarity to ideal solution (TOPSIS), and entropy weight-TOPSIS, and the corresponding vulnerability level zoning map was further drawn by using ArcGIS tools. The research results indicate that the vulnerability of the rainstorm-landslide disaster chain is high and relatively high in the western region, medium in the central and western regions, as well as southwest and northeast regions, and low and relatively low in the central, central and southern regions, and eastern regions in the Greater Bay Area. There are not only overlapping relationships but also certain triggering and synergistic effects between the vulnerability of different single disaster types in the same region, especially between high vulnerability areas, as well as between low vulnerability areas. The results can be promoted and applied in the vulnerability assessment of composite disaster systems, providing technical support for risk assessment and disaster reduction and prevention of composite disaster systems in China.

To ensure the safe and efficient operation of full-face tunnel boring machines (TBMs) in complex terrains, it is essential to clarify the load characteristics of cutters in the multi-cutter collaborative rock-breaking condition and to analyze the performance of cutter profiles in different geological strata. Therefore, a numerical discrete element model based on the particle-flow method for the multi-cutter collaborative rock-breaking condition was established. The load characteristics of flat-tipped and circle-tipped cutters under varying rock strength and rotational speeds of cutterheads were investigated. Additionally, multi-cutter rock-breaking experiments were conducted to verify the accuracy of the numerical analysis results. The findings indicate that under a given penetration depth, the circle-tipped cutter exhibits a normal total thrust that is 23%−50% lower than that of the flat-tipped cutter, along with a reduction in rock-breaking volume and specific energy by 10%−20%. The load of cutters at different installation radii varies. The innermost and outermost cutters only collaborate in rock breaking with adjacent single-sided cutters, so the cutting force is approximately 30% higher than that of the adjacent cutter. Consequently, the mean and the standard deviation of cutting forces show a “W”-shaped distribution, with higher values at both ends and lower values in the middle as the installation radius increases. The mean and standard deviation of the normal forces for both cutter profiles are positively correlated. However, at the same level of normal thrust, the flat-tipped cutter exhibits a 37%−50% lower standard deviation of normal force, which means the circle-tipped cutter may lead to more severe vibrations. Additionally, the cutting forces for both types of cutters increase with an elevation in the rotational speed of the cutterhead. The flat-tipped cutter exhibits greater sensitivity to variations in the rotational speed.

Forest fire detection is crucial for forest fire emergency rescue. To address the shortcomings of existing models in sample quality, multi-scale issues, and generalization capability across multi-view images, a method for forest fire detection based on YOLO (FFD-YOLO) was proposed. First, a multi-view visible light image dataset for detecting forest fire from of high point view (FFHPV) was constructed to enhance the model’s learning capability for multi-view fire information. Second, omni-dimensional dynamic convolution was introduced to develop an omni-dimensional spatial pyramid pooling (OD-SPP) to improve the model’s feature extraction capacity for multi-view fire characteristics. Finally, a wise intersection over union (Wise-IoU) loss function with a dynamic non-monotonic focusing mechanism was introduced to mitigate the impact of low-quality data on model precision and enhance small-target fire detection. Experimental results have demonstrated that FFD-YOLO increased precision by 3.9%, recall by 3.7%, mean average precision (mAP) by 4.0%, and F₁-score by 0.038 compared to YOLOv7. In comparative experiments with YOLOv5, YOLOv8, dense distinct query (DDQ), detection transformer with improved denoising anchor boxes (DINO), Faster R-CNN, Sparse R-CNN, Mask R-CNN, FCOS, and YOLOX, FFD-YOLO attained 75.3% precision, 73.8% recall, 77.6% mAP, and 0.745 F₁-score, validating its feasibility and effectiveness.

To meet the needs of human-robot collaboration, where an inspection manipulator actively cooperates with a person under the railroad car and to enhance the convergence speed of the proximal policy optimization (PPO) algorithm, an adaptive PPO (a-PPO) algorithm was proposed and innovatively applied in the online motion planning of the inspection manipulator. Firstly, the system model was designed to immediately output policy actions based on the current environmental state. Secondly, geometric reinforcement learning was introduced to construct the reward function, utilizing the agent’s exploration to continuously optimize the distribution of rewards. Thirdly, the clipping value was adaptively determined based on the policy similarity between before and after the update, and the a-PPO algorithm was developed. Finally, the improvement effects of the a-PPO algorithm were compared on two-dimensional maps, and the feasibility and effectiveness of its application were experimentally verified in both simulation and real train scenarios. The results indicate that in the two-dimensional plane simulation, the a-PPO algorithm shows certain advantages in convergence speed compared to other PPO algorithms. Additionally, the stability of paths has been improved, with the average length standard deviation being 16.786% lower than that of the PPO algorithm and 66.179% lower than that of the Informed-RRT* algorithm. In the application experiments in both simulated and real train scenarios, the manipulator demonstrates the capability to dynamically adjust target points and actively avoid dynamic obstacles during motion, reflecting its adaptability to dynamic environments.

As a strategic direction for future high-speed land transportation, the spatial alignment design of high-speed maglev railways has a decisive impact on system performance and safety. The latest research advances in spatial alignment design of high-speed maglev railways were reviewed. First, the development history of high-speed maglev lines was summarized, including Japan’s maglev test lines, Germany’s Transrapid system, China’s high-speed maglev engineering practices (e.g., test lines at Jiading Campus of Tongji University, Qingdao Sifang Company, Shanghai Airport, and Jiuli Campus of Southwest Jiaotong University), as well as ongoing and planned lines. Subsequently, the influence of spatial alignment of high-speed maglev railways on train stability was analyzed from three perspectives: the coupling effects of spatial alignment on levitation and guidance, the dynamic response mechanisms governed by alignment parameters, and the aerodynamic constraints on alignment configurations. Furthermore, the definition and composition of spatial alignment design were systematically elaborated, covering calculation and selection criteria for horizontal and vertical alignment parameters, combined horizontal and vertical alignment optimization, and turnout alignment studies. Current research bottlenecks were identified, such as inefficiencies in multi-physics coupling modeling and simulation efficiency, insufficient correlation between alignment parameter standards and dynamic performance, limitations in test line design theories and scenario coverage, challenges in global optimization and safety threshold quantification, low intelligence in alignment selection, difficulties in coordinating complex coupling constraints, immature multi-objective optimization methods for alignment selection and design, and inadequate integration of environmental impact assessment with alignment design. Finally, seven directions for in-depth studies were pointed out to advance the innovation and refinement of spatial alignment design theories for high-speed maglev railways.

To investigate the influence of ground motion uncertainty on the seismic demand and vulnerability of bridge structures and to clarify the propagation of this uncertainty in seismic vulnerability analysis, a quantitative method based on the Bootstrap method was proposed for assessing the uncertainty in the seismic vulnerability of bridges. Firstly, the relationship between the ground motion intensity index and the seismic demand of bridge structures was determined through probabilistic seismic demand analysis. Secondly, by considering the influence of ground motion sample size on the seismic demand model and vulnerability of bridge structures, the Bootstrap method was used to simulate the uncertainties in both probabilistic seismic demand model parameters and vulnerability curves. Finally, by taking a three-span simply supported beam bridge as an example, seismic vulnerability analyses were conducted using 50, 100, and 300 seismic records to quantify the variability of probabilistic seismic demand models and vulnerability under different ground motion samples. The results indicate that the seismic demand and vulnerability of bridge structures are subject to significant uncertainties under the ground motion. When 100 seismic records are used, the variability in failure probability of the bridge under various damage states exceeds 10%, and that under severe damage states reaches up to 30%. In seismic vulnerability analysis of bridges, it is advisable to represent the failure probability of bridge structures under different ground motion intensities as interval random variables to account for variability in seismic vulnerability due to seismic record samples. The Bootstrap method can effectively simulate the uncertainty in the seismic demand and vulnerability of bridge structures, providing an effective approach for statistical uncertainty simulation and seismic vulnerability analysis of probabilistic seismic demand models of bridge structures under small sample sizes.

To optimize the individualized comprehensive performance of plug-in hybrid electric vehicles (PHEVs), an optimization method for the shift schedule of single-shaft parallel PHEVs considering both dynamic and economic performance while reflecting the driving intention was proposed. Firstly, the switching logic among different operating modes was determined according to the demand torque, the engine characteristic curves, and the state of charge (SOC) of the power battery, and torque distribution strategies under different operating modes were formulated. Subsequently, a fuzzy inference method was used to establish a quantitative model for driving intention, which could calculate the driver’s expectations for dynamic and economic performance based on the driver’s operation and vehicle status. Then, by taking the driver’s expectations for dynamic and economic performance as the weights of corresponding sub-objective functions, a linear weighting method was used to construct a comprehensive performance evaluation function, thereby optimizing the shift schedules under different driving intentions. Finally, a simulation model was developed using MATLAB/Simulink, and simulations under the WLTC test cycle were conducted with initial SOC values of 0.5 and 0.9, respectively, using the optimal dynamic, optimal economic, and individualized optimal shift schedules. Simulation results show that under both SOC initial conditions, while reflecting the driving intention, the equivalent fuel consumption (EFC) of the individualized optimal shift schedules is reduced significantly compared to that of the optimal dynamic shift schedule, with reductions of 10.1% at an SOC of 0.5 and 11.8% at an SOC of 0.9. Meanwhile, the EFC of the individualized optimal shift schedules is increased compared to that of the optimal economic shift schedule, with increases of 5.3% at an SOC of 0.5 and 1.7% at an SOC of 0.9.

In order to reduce the impact of vehicle-induced vibration on the surrounding environment of high-speed railway bridges, firstly, a spherical bearing with built-in metal disc isolators for vertical vibration isolation of bridges was proposed, and the mechanical constitutive model and overall vertical stiffness calculation method of the bearings were given. The design compliance of the vertical stiffness of the metal disc isolator was studied by combining simulation and experimental comparison. Simulation was also used to analyze the influence of different friction support surfaces on the vertical stiffness and stress of the metal disc isolator. Secondly, through a series of tests on spherical bearings for vertical vibration isolation, the conventional performance, vertical stiffness, isolation load, dynamic and static stiffness ratio, and stiffness stability of the bearings were studied. Finally, taking the 32-meter-span concrete simply supported box girder of high-speed railway as the background, the vibration isolation effect of the bearings under the action of trains was explored. The results show that the deviation between the simulated and measured vertical stiffness values of the metal disc isolator with three different vertical bearing capacity designs is within ±10%. The friction coefficient of the bottom support surface of the metal disc isolator ranges from 0.01 to 0.10, with a 2.1% increase in vertical stiffness and a 0.9% decrease in stress. The conventional performance of the spherical bearing for vertical vibration isolation meets the design requirements, and the deviation between the test values and the design values of vertical stiffness and isolation load is less than ±10%. The vertical stiffness of the bearing remains stable after overload and unloading, providing protection for the metal disc isolator. At an excitation frequency of 1–17 Hz, the range of the dynamic to static stiffness ratio of the bearings is 1.00–1.15. The stiffness increase of the bearings after 10 million fatigue cycles is less than 10%, and all components are intact. The bridge supported by spherical bearings for vertical vibration isolation meets the requirements of train safety and riding comfort indicators. The soil vibration response attenuation of the former bridge is about 4 dB higher than that of the bridge supported by ordinary spherical bearings.

To accurately and efficiently evaluate the vibration damping performance of tracks, the German standard DIN V 45673 -4 provides a method for efficiently calculating the insertion loss rate, which can eliminate interference from stochastic factors such as line operation conditions and track irregularities. However, this method neglects the contribution of track bending stiffness in its equivalent model, leading to errors in identifying the resonant frequency of the wheel-rail system and the vibration damping frequency band of tracks. To increase the calculation precision, the model for calculating the German-standard insertion loss rate was improved on the premise that the computational efficiency was maintained. By employing the elastic foundation beam theory to approximate the actual structural dimensions and stiffness characteristics of tracks and considering the contributions of elastic components and track bending stiffness, the stiffness of the model was corrected. The plans for optimizing track dimensions and vibration damping performance of elastic components were discussed in terms of the 1–80 Hz vibration damping frequency band required by China’s environmental impact assessment by taking the floating slab tracks with vibration damping pads for example. The results show that after stiffness correction, the error in the resonant frequency of the wheel-rail system is reduced from 76% to 4.9%. The increase in the fastener loss factor can achieve the overall vibration damping performance within the 1–80 Hz frequency band. However, within the range of 30–90 kN/mm for fastener stiffness, reducing (increasing) the fastener stiffness improves the insertion loss rate of the 60–80 Hz (30–60 Hz) frequency band and decreases the rate of the 30–60 Hz (60–80 Hz) frequency band. This does not meet the overall vibration damping performance for the 1–80 Hz frequency band which can only be achieved when the fastener stiffness exceeds 90 kN/mm. Furthermore, lower stiffness of vibration damping pads or thicker floating slabs indicate higher improvement in fastener stiffness.

To address the problems of local buckling of cold-formed thin-walled steel members and cracking of ceramsite lightweight concrete, while considering the aesthetic requirements for interior building layouts, a prefabricated cross-shaped column partially encased with cold-formed thin-walled steel and filled with lightweight concrete was proposed. To investigate the seismic performance of these special-shaped columns, four cross-shaped columns were designed and fabricated using different coarse aggregate replacement rates as a parameter, and the low cyclic reversed loading tests were carried out. Based on the experimental study, the finite element software ABAQUS was used to analyze the lightweight aggregate concrete strength, steel plate strength, steel plate thickness, and loading angle. The test results indicate that the hysteretic curves of the four specimens are symmetrical and full, exhibiting a shuttle shape. A compression-bending failure mode of the specimens was observed. As the coarse aggregate replacement rate increases from 0% to 30%, 70%, and 100%, the specimen weight decreases by 77 kg/m³, 176 kg/m³, and 252 kg/m³, respectively; the carbon emission reductions decrease by 19.18%, 38.11%, and 49.93%; the ultimate load-bearing capacity decreases by 1.0%, 4.7%, and 9.2%; the ductility coefficient increases by 1.4% at first, and then decreases by 3.8% and 4.2%; the energy dissipation reduces by 8.6%, 2.5%, and 6.7%. The use of fly ash ceramsite to replace ordinary stone as a concrete coarse aggregate has no significant effect on the seismic performance of the columns but shows great potential for carbon emission reduction compared to ordinary concrete. Increasing the strength of lightweight aggregate concrete does not significantly improve the load-bearing capacity, ductility, or energy dissipation performance of the specimens. When the steel plate strength increases from Q235 to Q355, the ultimate load-bearing capacity of the specimens increases by 45.1%. When the steel plate thickness increases from 4 mm to 5 mm and 6 mm, the ultimate load-bearing capacity of the specimens increases by 14.8% and 35.5%, respectively. The least favorable loading angle for the specimens is 45°.

To further investigate the synergistic layout of aerodynamic braking devices on high-speed trains operating at 400 km/h and above and to clarify the overall braking benefit and efficiency of aerodynamic braking systems suitable for China’s current standard trainsets, the shape of the CR400AF platform and the configuration of its basic braking system were taken as a reference. Different numbers of “butterfly-type” aerodynamic braking devices were installed, and the aerodynamic characteristics of high-speed trains equipped with such devices under different operating conditions were simulated and calculated. A direct integration method applicable to aerodynamic braking problems was proposed. The braking performance of trains relying solely on aerodynamic braking devices at a given initial speed was compared with coasting to stop, and the braking effect was analyzed. Train braking equations were established, and the segmented accumulation method was used to calculate the braking distance and time when aerodynamic braking was combined with service braking and emergency braking. The results show that the installation of aerodynamic braking devices significantly increases the overall aerodynamic resistance of trains, and higher layout density leads to stronger aerodynamic interference between front and rear braking plates. The composite braking method combining aerodynamic braking effectively compensates for insufficient adhesive braking force at high speed, while addressing the low braking efficiency of aerodynamic braking at low speed. The combined braking distance is proportional to the square of the speed, and the braking time is proportional to the speed. With combined aerodynamic braking, the emergency braking distance from an initial speed of 350 km/h can be reduced to 5500 m or below.

To address the damage and deterioration of concrete materials in a sulfate environment in marine engineering, a concrete erosion test and microscopic test under different concentrations of sulfate solution and high temperature in the semi-immersed environment were carried out. By analyzing the mass change, dynamic elastic modulus, composition and content of eroded products, and sulfate ion content of concrete specimens and conducting the microscopic test, the damage and deterioration law of concrete under the high temperature and dry-wet cycle in semi-immersed and sulfate environment was revealed. The results show that in the early stage of sulfate erosion, sulfate invades the interior of concrete in the immersion zone and promotes hydration. The ettringite (AFT) and gypsum inside the concrete fill the initial gap, and the products play a filling and skeleton role. However, the continuous increase of the product amount in the later stage causes damage to the concrete, and the dynamic elastic modulus decreases by 12%–30%. The concrete in the adsorption zone is subjected to both the dry-wet cycle and the thermal cycle. The two cycles aggravate the capillary and diffusion effects so that the salt is easy to crystallize inside the concrete. Additionally, the thermal cycle accelerates the separation of aggregate and cement matrix, forming more pores, which is conducive to the continued intrusion of salt. The filling effect in the early stage of sodium sulfate crystallization improves the strength, and the mass increases by 0.5%–1.75%. However, the damage effect in the later stage is more serious.

To clarify the relationship between rockfall impact force and impact load in civil engineering, a comprehensive reflection coefficient is introduced to reflect the interaction between falling rocks, cushioning soil layers, and structures (a higher value indicates a more significant impact effect on the structure). A rockfall impact load calculation method based on wave theory is proposed. The size and distribution characteristics of rockfall impact loads were studied through experiments on arched structures with overlying cushioning soil layers subjected to rockfall impacts. The values and influencing patterns of the comprehensive reflection coefficient were obtained. The proposed calculation method was used to analyze the relationship between rockfall impact loads and rockfall impact forces. Through the research, it was clarified that the rockfall impact load on the structure presents a symmetrical parabolic distribution on the cross-section and can be characterized by a quadratic parabolic curve equation controlled by the maximum impact pressure peak at the arch crown and the structural span. The results indicate that within a range of 10 meters of free fall height for falling rocks and a cushioning soil layer thickness of 2.0 meters, there is a significant negative correlation between the comprehensive reflection coefficient and the thickness of the cushioning soil layer. When the thickness of the cushioning soil layer is 2.0 meters, its influence on the shape and free fall height of the falling rock is relatively small, and a value of 0.55 can be used. When the thickness is 1.0 meter and 0.5 meters, the comprehensive reflection coefficient of cuboid falling rocks is greater than that of spherical or conical falling rocks, and it is positively correlated with the falling height of the rocks. The relationship between the resultant force of rockfall impact loads on the structure and the impact force of rocks on the cushioning soil layer depends on the thickness of the cushioning soil layer and the shape of the falling rocks. When the thickness of the cushioning soil layer is 2.0 meters, the two are close, with the former slightly smaller than the latter, making the resultant force of rockfall impact loads equal to the rockfall impact force on the structure, which leans towards safety in structural design. However, when the thickness of the cushioning soil layer is less than 2.0 meters, the reverse is true, and the smaller the thickness, the greater the difference. When the thickness of the cushioning soil layer is 1.0 meter, the average increase of cuboid falling rocks is about 20 times larger than that of spherical or conical ones, and when the thickness is 0.5 meters, the average increase is about 30 and 10 times respectively for the two shapes. Under the same conditions, the resultant impact load of cuboid falling rocks is greater than that of spherical or conical ones, and the difference between them increases as the falling height of the rocks increases or the thickness of the cushioning soil layer decreases.

Self-sensing concrete materials for health monitoring have emerged as a new research focus in the field of structural engineering, yet there are challenges in the progress of their application and industrialization. To promote the application of self-sensing concrete in structural health monitoring, research on the effects of various conductive fillers on the performance of the concrete from the aspects of the dosage ratio, shape characteristics, secondary modification, and mixing with other kinds of fillers was introduced, and the significant achievements and milestones in the development of functional fillers for self-sensing concrete were reviewed. The testing and calibration standards for self-sensing functional fillers are not well-established. Different testing equipment and methods can significantly influence detection results, making it challenging to ensure comparability of results. Environmental adaptability assessments are inadequate. Complex environmental conditions (temperature, humidity, corrosion, etc.) have a substantial impact on material durability and service life, and there is insufficient research on the long-term stability of materials in actual operation. Quality control during mass production has not received sufficient attention. Disparities in raw materials and processes in large-scale production can severely affect the consistency of product performance. There are limited real-world engineering application cases. Conducting operational trials of intelligent self-sensing concrete with real-time multi-parameter monitoring and multifunctional coupling in large structures such as bridges and tunnels can supplement relevant data, offering promising research prospects for self-sensing concrete.

Rapidly obtaining co-seismic landslide distribution and conducting disaster assessments after earthquakes are vital for effective emergency relief and reconstruction. Therefore, in this study, the InSAR data-Newmark physical fusion driver model (IDNPM) was used to rapidly assess the landslides triggered by the earthquake in Jishishan, Gansu Province on December 18, 2023, with a view to quickly and accurately grasping the macroscopic distribution of landslide hazards. Firstly, through the time series SBAS-InSAR, it was revealed that there was serious gully development and retrogressive erosion in this area. These geological characteristics provided a favorable breeding environment for landslides. Secondly, the IDNPM was used to quickly evaluate the landslide of Jishishan earthquake, and it was predicted that the steep slopes and gully sides of Zhaomuchuan Village, Tashapo Village, and Dahejia Town were the high-risk areas for earthquake-induced landslide. Finally, based on the field investigation, numerical simulation, and satellite identification technology, the reliability of the model in practical application was proven. The results indicate that a total of 2.657% of the region is at high risk. There is a need to focus on such zones by urgently clearing and stabilizing slopes where landslides have occurred. For areas where no landslides have occurred, monitoring and assessment measures should be taken to guard against possible post-earthquake secondary landslide events. The research results can provide strong data support for emergency relief and reconstruction work after earthquakes in the affected areas.

To enhance the response efficiency of cross-regional emergency rescue under major natural disasters, considering differential disaster severity in affected areas, the optimization of cross-regional emergency supplies dispatching with combined transport was conducted. Firstly, a differentiated disaster classification strategy and a comprehensive evaluation system were proposed. The CRITIC-TOPSIS method was employed to determine the risk level of each region. Then, a bi-level programming model was developed, in which the upper level minimizes the total emergency response time and the lower level maximizes fairness. The upper level incorporated the Beetle Antennae Search to improve the Particle Swarm Optimization algorithm for finding solutions, thereby determining the shortest time and the volume of supplies transported from supply points to distribution centers. This provides basic data and time constraints for the lower level. The lower level uses the NSGA-III to solve the supplies allocation problem, where its results influence the distribution of supplies to affected areas in the upper-level model. This interdependence may lead to adjustments in the upper-level transportation scheme, further optimizing the overall objective. Finanly, taking 5•12 Wenchuan Earthquake as a case study for the simulation, the results indicate that, in terms of the total emergency response time, the scheme considering disaster severity classification is 2.53% shorter than that without considering disaster severity classification. Regarding fairness, the scheme under disaster severity classification shows a positive correlation between the satisfaction rate of emergency supplies demands and the disaster severity level at different disaster-affected points, thereby better reflecting the differentiated strategies based on disaster severity levels and the fairness of emergency supplies dispatch.

To enhance the accuracy and efficiency of crack detection of ancient bridges and address the issues of information loss and secondary damage caused by traditional sensor detection methods, a crack identification and measurement method was proposed based on an improved You Only Look Once 11 (YOLO11) and SegFormer. First, to overcome the limitations of the YOLO11 model, including its large parameter size and restricted inference speed, the You Only Look Once-crack detect (YOLO-CD) object detection model was introduced. The StarNet lightweight backbone network was employed to reduce computational costs. The HSANet neck network was integrated to enhance the ability to preserve the crack edge detail, and an optimized spatial context detection (OSCD) head was designed to improve multi-scale detection efficiency. Second, an enhanced SegFormer-HF semantic segmentation model was proposed, which incorporated a feature fusion module (FFM) and a high-low frequency decomposition block (HLFDB) to mitigate information loss during sampling and improve semantic consistency in crack segmentation. Finally, a joint detection-segmentation framework was developed, combining a skeleton line algorithm to achieve automatic calculations of crack length and width. Based on the experiments conducted on the crack dataset of ancient bridges, the results have demonstrated that the YOLO-CD model achieves F1 score, mAP50, and mAP50-95 values of 67.8%, 71.5%, and 46.4%, respectively, while reducing floating-point operations (GFLOPs) by 47.6% compared to YOLO11. The SegFormer-HF model achieves superior performance with F1-score, mIoU, and mPA of 91.50%, 90.51%, and 85.15%, respectively, outperforming existing mainstream models. The results validate that the proposed method achieves higher efficiency and compact model size while balancing detection speed and accuracy, which is suitable for deployment on mobile devices such as cameras and drones.

To resolve the difficulty in controlling heavy-haul trains operating in complex environments caused by insufficient driver experience, a multi-mass dynamic model for multi-locomotive traction was established based on the Locotrol synchronous control principle of the Datong–Qinhuangdao Railway. A controller was designed for the main locomotive, where the total time-varying unknowns, including coupler forces, running resistance, and external disturbances, were regarded as aggregated uncertainties. The acceleration of these uncertainties was further treated as an extended state, enabling real-time estimation and compensation via an extended state observer. Moreover, the fast terminal sliding mode control was introduced to improve the nonlinear error feedback control law in active disturbance rejection control, and an improved adaptive reaching law was employed to refine the dynamic quality of the sliding mode reaching motion. Simulations were conducted on a heavy-haul train with the formation of “1 + 105 + 1 + 105 + controllable end” by incorporating actual line data from Datong–Qinhuangdao Railway and expert driver experience, and compared with traditional methods. The simulation results demonstrate that, compared to conventional sliding mode active disturbance rejection control, the proposed method reduces control force chattering in master-slave locomotives by 23.7%, improves tracking accuracy by 19%, and confines tracking errors within ±0.7 km/h.

In order to investigate the influence of the number of ballast particle fracture surfaces on the direct shear performance of the ballast bed, pebbles were crushed to obtain ballast aggregates with different numbers of fracture surfaces. Direct shear tests were carried out under different vertical stresses to obtain the stress–strain relationship and deformation characteristics of ballast aggregates. Based on formula calculation, the variation laws of peak shear strength and internal friction angle of ballast aggregates with vertical stress were obtained. The results show that, in terms of strength characteristics, when the number of fracture surfaces is 0, 1, 2, and 3, the shear strength and internal friction angle of ballast aggregates under the same vertical stress increase with the number of fracture surfaces. The shear strength increases by 14.7%–25.6%, 12.2%–27.4%, and 6.0%–10.1%, respectively. In terms of deformation characteristics, the shear shrinkage of ballast aggregates increases with fracture surface number, with a maximum increase of 76.4%, while the shear dilation decreases with a maximum decrease of 20.8%.

In order to effectively characterize the mechanical response of vehicle-end contact and coupler instability during high-speed train collisions, a contact force calculation method for the longitudinal impact of a thin-walled structure was established, which considered the impact of vehicle misalignment on contact force and contact moment. Characterization methods for the load characteristics of different coupler-buffer devices after the crushing stroke were then established. Finally, based on these two methods, a three-dimensional (3d) train collision dynamics model was constructed considering the vehicle-end contact and coupler instability. The dynamics model results were compared with those from the finite element model (FEM) under two working conditions. The results show that the proposed method can better reflect the contact force responses of different thin-wall structures at different impact speeds, with a maximum relative error of 9.83% compared to the finite element results. The characterization method can effectively distinguish the post-crushing load characteristics of different types of coupler-buffer devices. The developed 3D collision dynamics model is in good agreement with the finite element calculation results in key indicators such as vehicle speed responses, collision interface force responses, and vertical responses of the carbody.

The floating charge condition of lithium-ion batteries widely exists in scenarios such as backup power sources and communication base stations, and is a special condition that tends to stabilize. This stability poses a challenge to the quantitative diagnosis of internal short circuit (ISC) in batteries under this condition. In this study, a quantitative diagnosis method for early ISC in lithium-ion battery packs based on intermittent charging was proposed. This method utilized a repeated “charging-rest” process to calculate the equivalent leakage current according to the relationship between charging capacity and leakage, thereby achieving rapid quantitative diagnosis of ISC. The simulation and experimental results show that the proposed method has a diagnostic accuracy of less than 2% and a detection time of about 33 minutes for a micro-ISC battery with an ISC resistance of 500 Ω. It achieves early-stage and high-precision quantitative diagnosis of battery ISC under floating charge conditions. In addition, compared with conventional constant voltage source methods, the proposed method improves the accuracy of diagnosing short circuits within 100 Ω by at least 16 times. The proposed ISC method has a very low computational burden and is of great significance for improving the safety of battery packs.

In order to reveal the air pressure variation law and the subsidence mechanism in covered karst soil cave induced by precipitation, according to the theory of short gas pipe submerged flow, calculation methods of gas seepage flow, air pressure, and stability coefficient in ellipsoid cave were obtained. MATLAB program was compiled based on finite difference numerical solutions. The feasibility of calculation methods was verified through indoor model tests of subsidence induced by precipitation in a karst soil cave. The example analysis has shown that the gas state parameters (flow and pressure) and stability coefficient of the cave evolved from the initial state to drastic variations in the early stage of precipitation, then shifted to gradual changes in the later stage, and finally returned to the initial state. The maximum peak flow of soil cave induced by precipitation is positively correlated with the length of the semi-minor axis b of the ellipsoid cave, and negatively correlated with the ratio of semi-major axis and semi-minor axis $ a / b $, and arch height. The minimum peak air pressure is positively correlated with $ a / b $, $ b $, and arch height. The arrival time of the minimum peak air pressure is positively correlated with arch height, and negatively correlated with $ a / b $, while the effect of $ b $ is negligible. The minimum peak stability coefficient of soil cave induced by precipitation is positively correlated with $ a / b $ and arch height and negatively correlated with $ b $. The arrival time of the minimum peak stability coefficient is positively correlated with arch height, and negatively correlated with $ a / b $, while the effect of $ b $is negligible.

For the purpose of improving the conveying efficiency of the vacuum pneumatic slagging system of the shaft boring machine (SBM) and addressing low conveying efficiency caused by the mismatch between the parameters of the slagging system and the rock slag, the effect of conveying system parameters on slagging efficiency was investigated based on single factor analysis method and orthogonal test method. Firstly, a parameter and pressure loss calculation model for the vacuum pneumatic slagging system was constructed based on fluid mechanics to determine the key parameters of the system. Then, the Fluent software was used to simulate the process of vacuum pneumatic slagging, and the outlet velocity of rock slag and the average gas pressure drop were taken as the consideration index of slag conveying efficiency. The single factor analysis method was used to study the influence of four factors, including inner diameter of pipe, gas velocity, rock slag particle size, and rock slag density, on the conveying efficiency. The multi-factor analysis was carried out based on the orthogonal test method, and the non-dominated sorting genetic algorithm was applied to obtain the Pareto frontier solution set. Finally, the slag conveying efficiency test of the vacuum pneumatic slagging system was carried out. The results show that the influence of gas velocity and rock slag particle size on the outlet velocity of rock slag is the most significant, and the influence of inner diameter of pipe and gas velocity on the average gas pressure drop is the most significant. In addition, the average gas pressure drop and the outlet velocity of rock slag cannot reach the optimum simultaneously. When the minimum value of the outlet velocity of rock slag is selected as the best economic conveying point, the optimal combination of conveying parameters is as follows: rock slag particle size of 10 mm, inner diameter of pipe of 150 mm, gas velocity of 40 m/s. The research results can provide a reference for the construction application of the vacuum pneumatic slagging system of SBM.

To construct a monitoring system of preventive protection for ancient masonry arch bridges, a monitoring method for risk identification was investigated. Three indicators, which were damage assessment grade, Von Mises stress, and component importance, were used to quantify the most severe damage, unfavorable stress, and critical components. The monitoring target values were solved for the 64 components of the Lugou Bridge based on the loss matrix, force matrix, and importance matrix, and a sensor placement scheme was made accordingly. The results have shown that the method can identify high-value components for monitoring and capture the seasonal fluctuation patterns and cumulative damage risks of Lugou Bridge. Except for the settlement, monitoring data exhibits significant seasonal fluctuation patterns, with peaks in June to July and troughs in January each year. The ratio of winter to summer peak values is 1.577 for strain sensors, 0.849 for displacement sensors at the seventh pier from the east, 1.206 for displacement sensors at the ninth pier from the east, and 1.549 for transverse inclination sensors. The average seasonal fluctuation ratio ranges from 20% to 60%. The settlement of the fifth pier from the East is 1.156 times that of the ninth pier from the East. Sensors near the central arch bridge or located in severely damaged areas have higher peak values among the same type of sensors. The study provides a scientific basis for the monitoring of preventive conservation of ancient masonry arch bridges.

To address the limitations of difficult convergence to the global optimal solution with fixed step search, strong dependence on the selection of initial growth point, and huge growth space for the plant growth simulation algorithm (PGSA), a new strategy for search mechanism of adaptive variable step, Gauss perturbation mutation mechanism, and screening mechanism of growth space was proposed. On this basis, the PGSA based on multi-mechanism fusion (multi-mechanism fusion PGSA) was established. The prestress optimization of suspended domes was further carried out by using the multi-mechanism fusion PGSA and compared with other algorithms. The results show that compared with the original PGSA, the introduction of search mechanism of adaptive variable step can avoid the algorithm falling into local optimal solutions; the introduction of Gauss perturbation mutation mechanism can solve the problem of poor optimization results caused by the improper selection of initial growth points, and the introduction of screening mechanism of growth space can effectively terminate the growth after the algorithm converges, thus significantly reducing the growth space by 97.64%. The number of iterations of multi-mechanism fusion PGSA is the smallest (only 45), and the absolute value of the average horizontal radial reaction of supports after optimization is minimal (only 0.004 kN) in comparison with other algorithms. Therefore, the applicability of this algorithm is verified.

Freeze-thaw cycles are among the primary factors affecting the limestone cultural relics in northern China. These cycles often result in various forms of surface weathering, seriously threatening the long-term preservation of these cultural relics. Water immersion freeze-thaw simulation weathering experiments were conducted on fresh limestone. The development patterns of physical and mechanical property indicators were obtained by utilizing various characterization techniques. By examining variations in pore structure, the freeze-thaw damage mechanism of limestone was quantitatively revealed from both macro and micro scales, and a comprehensive evaluation of weathered limestone was performed using an entropy weight-linear weighting method. The results have shown that after 50 freeze-thaw cycles, the P-wave velocity and surface hardness significantly decrease, with a loss rate of over 10%. The capillary water absorption coefficient increases by more than one time; The uniaxial compressive strength decay rate was 30.6%. As the number of cycles increases, the structural integrity of the compressed limestone becomes worse. The pores of limestone are primarily composed of mesopores (0.1- 1000 μm). Freeze-thaw cycles lead to an increase in both the number and volume of pores, accompanied by particle wear and the expansion of cracks. The mechanical-property half-life is a key parameter for evaluating limestone’s freeze-thaw resistance. A multivariate regression model based on non-destructive measurements can effectively predict the variation in uniaxial compressive strength. The capillary water absorption coefficient exhibits the greatest sensitivity to weathering damage. The introduction of an integrity index enables a multidimensional and quantitative assessment of the weathering severity of building limestone. The research findings provide a theoretical basis and practical guidance for the scientific understanding of limestone materials and the assessment of the current state of cultural relics’ weathering.

In order to study the mechanical properties of aeolian sand concrete (ASC) under axial compression with different basalt fiber (BF) contents, the experiment took concrete with 0% fiber content as the reference group and designed the basalt fiber–aeolian sand concrete (BF-ASC) with different fiber content of 0.05%, 0.10%, 0.15%, and 0.20%. The influence of the BF volume fraction on the axial compressive strength, the peak stress, the peak strain, and the elastic modulus of ASC was analyzed. The results show that the peak stress and elastic modulus of the concrete first increase and then decrease with the fiber volume fraction. At 0.10% BF, the peak stress and elastic modulus of the concrete are 115.6% and 112% of the reference group, respectively. The peak strain and toughness indices increase with the volume fraction of the fiber. At 0.20% BF, the peak strain and toughness indices increase by 34.92% and 7.2% compared to the reference group. The entire stress–strain curve of BF-ASC undergoes three stages of elastic, elastoplastic, and failure, just like ordinary ASC. The BF-ASC constitutive relation can be described in terms of segments based on the Carreira and Chu model and the Guo Zhenhai’s model. The ascending profile is consistent with the Carreira and Chu models, and the descending profile is consistent with the Guo model. In addition, a regression analysis is conducted on the BF-ASC uniaxial compressive constitutive model considering the BF content. The correlation coefficients are all greater than 0.98, and the model has a high degree of agreement with the experimental curves.

To achieve digital modeling and performance evaluation of ancient stone arch bridges, this study researches the reverse modeling method based on Unmanned Aerial Vehicle (UAV) oblique photography and image contour extraction technology. Firstly, a UAV is used to collect multi-view sequence images of the stone arch bridge. Secondly, the Structure from Motion (SfM) and Multi-View Stereo (MVS) algorithms are used to construct three-dimensional (3D) model of stone arch bridges. Then, based on the characteristics of color difference between stone blocks and mortar as well as the geometric regularity of stone blocks, strategies of color difference enhancement and small-area impurity filtering are proposed to improve the Canny edge detection. Cyclic quadrilateral recognition and shape optimization are introduced to improve the polygon approximation algorithm, so as to realize the automatic identification of surface contours. Subsequently, the real scale is calibrated based on ground control points, and the finite element model is generated through parametric modeling using the extracted contour coordinates. Finally, the proposed method is applied to model Toulong Bridge and analyze its performance, which is compared with experimental results. The study shows that no obvious diseases are detected on the surface of the 3D real-scene model of Toulong Bridge, with a maximum dimensional error of 0.8%; the maximum calculation error of the deflection is 2.1% by the finite element model. These indicate that the method can accurately reflect the geometric shape and mechanical properties of ancient stone arch bridges, providing technical support for their digital protection and performance evaluation.

The welded frame-type bogie is a newly developed product in recent years, and its operational safety and reliability are crucial. A fatigue reliability assessment of the welded frame-type bogie frames was carried out. A fatigue life assessment procedure for welded structures was proposed based on the equivalent structural stress (ESS) method and the main S-N curve model, and a formula for determining the stress state of welded structures under multiple loads was derived. According to the BS EN15085-3:2007 standard for the design of welded structures in railway vehicles, combined with finite element model simulations and fatigue test data, the stress state and fatigue life of the bogie frame weld joints were comprehensively analyzed. A finite element model including weld details was established to simulate the stress state under actual operating conditions. Fatigue life simulations were performed using the load spectrum provided by the fatigue test outline, and the stress state level of the weld joints was determined according to the standards to assess the quality grade and inspection grade of the welds. Fatigue tests of the bogie frames were conducted according to the EN13749:2011 standard. The results show that the ESS method, combined with the BS EN15085 standard, can accurately predict the fatigue life of weld joints. The total damage of key welds in the bogie frames is less than 1, meeting the design requirements for fatigue life. After fatigue tests, no cracks are detected by magnetic particle inspection, meeting the fatigue strength requirements. The maximum stress factor of the frame welds calculated by ESS is 0.939. The stress state level of each key weld is clarified based on the stress factor values, providing a basis for optimizing the quality and inspection grade of the welds.

To investigate the dynamic performance of prefabricated slab tracks (PSTs) applied in metro turnout areas, an analysis was conducted based on the interlayer contact relationship between the slab and the pad considering the constraint effect, as well as the multi-point contact theory in turnout areas. By taking a typical PST as an example, the safety performance in terms of concrete strength and ultimate bending moment capacity under train load was verified. A coupled vehicle–turnout–tunnel dynamic model was established, and a self-developed co-simulation program was used to study the system dynamic responses and vibration reduction effects during train passage through the metro turnout areas under different slab thicknesses and pad stiffnesses. The results show that under the load condition of metro type-A trains, the maximum tensile stresses in the track slab and self-compacting concrete layer are 2.48 MPa and 1.89 MPa, respectively. The cross-section bending moment capacities of longitudinal and transverse reinforcement in turnout areas are significantly greater than the lateral and longitudinal load moments. When the train speed is 55 km/h and the slab thickness increases from 180 mm to 300 mm, the insertion losses are 8.1 dB, 9.3 dB, 10.0 dB, and 10.7 dB, and the dynamic responses all meet the safety requirements. When the slab thickness is 260 mm and the pad stiffness increases from 0.01 N/mm³to 0.04 N/mm³, the insertion losses are 15.0 dB, 10.0 dB, 8.0 dB, and 5.2 dB, respectively. At a stiffness of 0.01 N/mm³, the vertical displacements of the switch rail and nose rail are 4.1 mm and 5.2 mm, respectively. Considering the safety performance, economic benefits, and vibration reduction effects comprehensively, it is recommended that the slab thickness of the PST is between 220 mm to 260 mm, and the pad stiffness range from 0.019 to 0.030 N/mm³.

To study the self-sensing performance of ultra-high performance concrete (UHPC) mixed with steel fibers and multi-walled carbon nanotubes (MWCNTs) under different cyclic stress amplitudes, experimental studies were conducted on UHPC specimens with a steel fiber volume content of 2% and varying MWCNT contents. The results show that the initial resistivity of UHPC increases first and then decreases with the increase in MWCNT content, and the addition of 0.15% MWCNTs improves the conductivity of UHPC. When the MWCNT content is 0.15%, the sample exhibits optimal repeatability, with a repeatability coefficient of 0.019, and the linearity change of alternating current (AC) resistance presents a strong linear relationship with stress, with a linearity of 0.97. The stress sensitivity and strain sensitivity of the samples UHPC0 and UHPC0.05 first increase and then decrease with the increase in stress, while the stress sensitivity and strain sensitivity of samples UHPC0.1 and UHPC0.15 show a gradually decreasing trend. The maximum strain sensitivity and stress sensitivity of UHPC0.15 are 71.6% and 0.16%/MPa under different cyclic stress amplitudes, both appearing at a stress of 10 MPa. When the content of MWCNTs is 0.15%, UHPC exhibits the best self-sensing performance.

To investigate the influence of the axial compression ratio on the hysteretic properties of the steel shell-concrete composite pylon, based on the composite pylon structure without longitudinal rebars, three hysteretic specimens were designed with the axial compression ratio as the research parameter. Through testing, the hysteresis curves, failure characteristics, and strain development of each specimen were obtained, and the mechanical behavior under large eccentric failure was analyzed. A finite element model was then established using ABAQUS for further analysis, and the boundary failure conditions of the pylon section were determined. Then, calculation formulas for the axial compression and bending moment of the section under boundary failure were proposed, and the effect of the steel ratio and concrete strength on the axial compression ratio under boundary failure was discussed. The research results indicate that under large eccentric failure, the section stiffness, peak bearing capacity, and energy dissipation capacity increase with the axial compression ratio. When the axial compression ratio increases from 0.056 to 0.166, the stiffness and the flexural capacity of the specimen improve by 20%. The boundary failure condition of the composite pylon section is defined by the yielding of the tensile-side steel shell and crushing of the compressive-side concrete. Under boundary failure, the section achieves its highest flexural capacity and stiffness. The proposed calculation formulas provide an accurate assessment of the axial compression ratio and flexural capacity under boundary failure. Both an increase in steel ratio and concrete strength lead to a reduction in the axial compression ratio at boundary failure. The axial compression ratio under boundary failure in the composite pylon section falls within the range of 0.44–0.56, making it well-suited for long-span suspension bridge towers with higher axial compression ratios.

The large eddy simulation (LES) was employed to make a transient simulation of the flow field within the grid flocculation tank to investigate the evolutionary characteristics of the jet vortex flow structure of flow field within the grid flocculation tank. The grid flow field was analyzed from both two-dimensional and three-dimensional perspectives. The results indicate that a jet vortex flow field is formed immediately behind mesh holes as fluid flows through a grid plate. Due to shear, entrainment, and mixing between jet and background fluid, a backflow vortex zone is formed in the region behind the grid, accompanied by a continuously developing vortex ring structure along the side wall. The vortex ring structure causes varying degrees of deformation and displacement at the front of the jet, while also suppressing its forward movement. The vortices are mainly located within the boundary layer of the jet, with rapid changes occurring in their structure at its forefront. This area exhibits both maximum size and intensity. The most significant variations in vortex structure intensity are observed near the side wall, where the vortex structures of each jet display mirror symmetry about its axis. Additionally, the front of the three-dimensional vortex structure resembles a coronal formation. As the jet develops forward, the coronal structure will extend and swell to become larger and then will eventually discrete and detach. The distribution of vortex structure at each moment exhibits mirror symmetry with respect to the bisector of the flow field, while the variation process of the flow field morphology demonstrates a trend from the side wall towards the center of the flow field.

A convolutional-bidirectional long short-term memory neural network-attention mechanism (CNN-BiLSTM-AM) prediction model optimized by the northern goshawk optimization (NGO) algorithm for landslide displacement was proposed to address challenges that a single prediction model fails to effectively extract complex sequence features and that manual parameter tuning tends to fall into local optima in current landslide displacement prediction research. Firstly, according to the factors affecting the landslide, the multivariate empirical mode decomposition (MEMD) algorithm was used to decompose various landslide displacement data into trend and periodic components. The trend components were predicted using the autoregressive integrated moving average (ARIMA) method. For the periodic components, influencing factors were identified through the gray correlation degree, and a CNN-BiLSTM-AM combined model was constructed for prediction. The optimal hyperparameters of this model were obtained through NGO. Then, by considering the lag of the periodic components, the Spearman correlation coefficient was used to select the optimal lagged displacement to further enhance the model’s predictive performance. Finally, the model was validated using monitoring data of the Tuojiashan Landslide in Weiyuan, Gansu Province. The results show that the RMSE and MAE of the total displacement prediction of the Tuojiashan landslide are as low as 0.22 mm and 0.37 mm, respectively, showing the prediction accuracy of the correction, while the R²reaches 0.98, which fully verifies the validity and reliability of the proposed model in landslide displacement prediction.

To investigate the compression performance of cold-formed thin-walled steel T-shaped composite edge columns with web stiffeners, axial and eccentric compression tests were conducted on eight groups of specimens. The influence of “V”-shaped longitudinal stiffening ribs on the failure modes and bearing capacity of the components were revealed through finite element model validation and parameter analysis, and an improved calculation method for bearing capacity was proposed. The results indicate that under axial compression, local buckling first appears in the web of the T-shaped composite edge column without stiffening ribs, ultimately leading to overall crushing failure. After adding “V”-shaped stiffening ribs, the stiffness of the single-limb C-shaped steel web is enhanced; the local buckling mode of the T-shaped composite edge column is improved, and the bearing capacity increases by approximately 15%. As the eccentricity increases, the failure modes of the specimens remain similar, and the ultimate bearing capacity shows a decreasing trend. The bearing capacities under axial and eccentric compression predicted by the effective width method are conservative. Both the finite element results and the test results are greater than the calculated results, with the average ratios being 1.238 and 1.143, respectively. After modification, the ratio of the results predicted by the effective width method to the simulated values ranges from 1.000 to 1.074, indicating high prediction accuracy.

To study the effect of cable breakage on the impact response of concrete-filled steel tube arch bridges and the difference in safety factor requirements between carbon fiber reinforced polymer (CFRP) cables and steel cables, the dynamic response of a railway bridge under accidental cable breakage was analyzed. A spatial finite element model was established by ANSYS. The force characteristic variations of the residual structure of the arch bridge under five cable breakage conditions were studied based on the equivalent unloading method. The impact sensitivity of the structure after cable breakage was evaluated by dynamic amplification factor ( D _DAF) and demand capacity ratio ( D _DCR). The effects of different cable materials, namely steel cables and carbon cables, on the dynamic response of the arch bridge were compared. The results show that the dynamic response of the main girder and the stress of the arch rib are greatly affected by the position and number of cable breakages. The redistribution ratio of the cable force is inversely proportional to the distance from the broken cable area and the cable length and directly proportional to the number of failed cables. The D _DAFof the arch bridge with carbon cables is higher than that of the arch bridge with steel cables, ranging from 1.19 to 1.43. The D _DCRof the remaining cable after cable breakage does not exceed 1, indicating large redundancy. Compared with bridges with steel cables, arch bridges with carbon cables require smaller safety factors under cable breakage conditions, ranging from 1.0 to 1.5.

To realize the requirements of minor post-earthquake damage, rapid repair, and functional recovery of reinforced concrete frame structures, three 1/2 scaled concrete frames were designed. One was an ordinary reinforced concrete frame, and two were concrete frames reinforced with high-strength steel bars (HG bars). Quasi-static tests were carried out to study the failure modes of the frames under cyclic loading. The effects of beams and columns with HG bars on seismic performance indexes including hysteretic curves, skeleton curves, residual deformation, repairability, and self-centering ability, were discussed. The results show that the use of HG bars in beams and columns effectively improves the overall bearing capacity and deformation capacity of the frame. Compared with the ordinary reinforced concrete frame, specimens NHGS2.5A15 and HGHGS2.5A15 show good displacement hardening effects. Their ultimate bearing capacities increase by 23% and 57%, respectively, and the displacement corresponding to ultimate load increases by 50% and 60%, respectively. These specimens have smaller residual deformations and higher reparability, and they demonstrate good self-centering capability and repairability performance.

The cyclic dynamic stress generated during train operation presents a significant challenge to the dynamic strength of subgrade fill materials. Existing research has mostly simulated train loads using continuous loading methods, which fails to fully reflect the intermittency of these loads. To investigate the differences in dynamic strength of loess subgrade under continuous and intermittent loading, a series of consolidated undrained tests under continuous and intermittent loading conditions were conducted using a GDS dynamic triaxial apparatus. The influences of confining pressure and dynamic stress amplitude on the dynamic strength of the soil were examined. The effects of different loading methods on the dynamic strength and strength parameters of the subgrade loess were compared. The experimental results indicate that the dynamic strength of the loess subgrade increases with higher confining pressure, but the growth rate diminishes gradually. Both dynamic cohesion ( c _d) and dynamic friction angle ($ {\varphi _{\text{d}}} $) decrease with the increase in the failure cycles (lg N _f), showing an overall linear relationship. Under intermittent loading, the soil exhibits a marked increase in c _dand$ {\varphi _{\text{d}}} $compared to continuous loading, with c _dincreasing by 2.18%–5.09% and $ {\varphi _{\text{d}}} $ by 4.03%–13.78%. By normalizing the dynamic strength using the static triaxial shear strength, an empirical formula for the dynamic strength of the loess subgrade based on static strength is proposed, which provides a critical basis for assessing the stability of the subgrade under dynamic loads.

This study aims to address the issue of vortex-induced vibrations (VIV) in long-span bridges under low wind speeds, which can lead to structural fatigue of the bridge and affect driving comfort. Based on the wake oscillator model and a variable-damping coefficient eddy current damper, a semi-active control strategy was developed. Firstly, a dimensionless VIV force model of the bridge wake oscillator was established, and its parameters were fitted using experimental data via a genetic algorithm. Then, a variable-spacing ball screw eddy current damper was designed, and the corresponding relationships between the damping coefficient and the axial velocity–air gap, as well as the damping force and the axial velocity–air gap, were determined through COMSOL simulations. Next, a genetic algorithm was applied to optimize the semi-active control parameters for the selected linear quadratic regulator (LQR) and sliding mode control (SMC) algorithms. Finally, a comparative study was conducted on the VIV suppression effects of an uncontrolled system, LQR, and SMC semi-active control by using the Hei-Bai-Shui River Bridge as the engineering case. The results show that the wake oscillator model accurately describes the VIV characteristics of the bridge. At the maximum VIV wind speed of 16.5 m/s, LQR and SMC semi-active controls can reduce the bridge amplitude to 4.95% of the uncontrolled amplitude, which is well below the regulated limit. Overall, the damping effects of LQR and SMC control are similar, but under the LQR control, the air gap of the damper remains unchanged, while under the SMC control, the air gap varies periodically. The former offers more favorable conditions for engineering implementation.

To study the problem of rail corrugation-induced clip fracture in metro sections with double-layer nonlinear vibration damping fasteners, by taking the typical GJ-Ⅲ type fastener as the research object, field investigation and numerical simulation were combined to analyze the causes and influencing factors of fastener clip fracture in this section. Firstly, a finite element model of the wheel–rail–fastener system incorporating rail corrugation was constructed. Subsequently, the instantaneous dynamic analysis method was employed to investigate the causes of fastener clip failure in the rail corrugation section from the perspective of resonance response. Then, based on cumulative fatigue damage theory, the fatigue life of the fastener clips on both sides of the low rail was compared under conditions with and without rail corrugation from the perspective of fatigue characteristics. Finally, a parametric analysis was conducted to explore the influence of external rail corrugation excitation and internal characteristics of fastening components on the fatigue life of the fastener clip. The results show that the high-frequency excitation induced by rail corrugation leads to the resonance in the GJ-III type fastener clip, which is the main cause of the clip fracture. Rail corrugation aggravates the vibration responses of the wheel–rail system, reduces the clip’s service life, and has a more serious impact on the outer clip of the low rail. It cuts the fatigue life to 2.18 × 10⁵cycles, which is only 4.36% of the design life. In terms of external excitation from rail corrugation, reducing the corrugation depth and increasing the corrugation wavelength can extend the fatigue life of the clip; moreover, when the corrugation wavelength exceeds 40 mm, the fatigue life improves significantly. In terms of the internal characteristics of fastener components, reducing the elastic modulus of the clip, increasing the Poisson’s ratio of both the clip and the rubber pad, and increasing the rubber pad’s elastic modulus can reduce the fatigue damage of the clip to some extent, thereby mitigating clip fracture in the rail corrugation section.

To develop an optimal sensor placement method for ancient stone arch bridges, by taking the Beijing Lugou Bridge, a national key cultural relics protection unit, as an example, a sensor optimization model considering initial damage and random material parameters was established. A fitness function design and solution method considering complex monitoring targets was proposed, along with a meta-genetic algorithm based on the concept of meta-learning for solving the sensor placement optimization problem. The proposed method was compared with two optimization methods based on conventional genetic algorithms, achieving optimal sensor placement for ancient stone arch bridges. The results show that the proposed method offers better parameter identification capability, damage sensitivity, and information redundancy level. When the noise level is within 5%, the sensor placement scheme given by the meta-genetic algorithm can successfully detect the damage, while the other two methods achieve only a 60.0% success rate. When the noise level reaches 10%, the meta-genetic algorithm can detect 60.0% of the damage, while the other two methods fail to detect damage effectively.

To consistently describe the mechanical response of sand and clay under generalized stress paths, a unified critical state constitutive model (CASM-SG) applicable to generalized loading conditions was proposed based on the unified constitutive clay and sand model (CASM) with state parameters and by employing the subloading surface theory and the transformed stress method. In the model based on the original CASM model, a plastic internal variable associated with the initial state of the soil was established by using the concept of subloading surface, and the original two-dimensional yield surface determined from triaxial compression tests was transformed into the three-dimensional stress space through the transformed stress method. A complete constitutive framework was constructed for the CASM-SG model under generalized stress conditions, including the stress dilatancy relationship and the hardening rule. Explicit expressions for the plastic modulus and the elastoplastic stiffness matrix were derived based on the consistency condition. Finally, the proposed model was employed to simulate the mechanical behavior of Hostun sand and Fujinomori clay under drained and undrained triaxial compression and extension conditions. The simulation results indicate that the CASM-SG model can accurately capture the mechanical behavior of both sand and clay under various stress paths. For Fujinomori clay, the triaxial extension strength decreases by approximately 24% compared with the triaxial compression strength, and the CASM-SG model captures this characteristic. Compared to the original CASM model, the CASM-SG model introduces two additional material parameters with clear physical interpretations, demonstrating a favorable balance between modeling accuracy and simplicity.

To simplify the steel shell–concrete composite pylon structure and improve construction efficiency, a novel ribbed straight-hooked rebar (RSHR) shear connector was studied. Firstly, the push-out and pull-out tests of the shear connector were designed. The shear bearing capacity, pull-out bearing capacity, and failure characteristics of each specimen were obtained. Secondly, the corresponding relationship between the failure mode and the bearing capacity of the specimen was obtained by using finite element analysis software. Finally, based on model analysis, the influence of the burial depth on the shear connector performance was further discussed, and the formula for calculating the shear and pull-out bearing capacity of the RSHR shear connector was proposed. The results show that under shear loading, the RSHR shear connector undergoes yielding of its stiffening ribs, while under pull-out loading, concrete punching failure occurs. Along with the yielding of the straight-hooked rebar, the difference in failure modes can cause the shear connector’s bearing capacity to vary by up to five times. Under push-out loading, the steel–concrete bonding force accounts for 30% of the total bearing capacity. The position of the straight-hooked rebar determines its stress characteristics and failure modes under pull-out loading. Reducing the spacing between the straight-hooked rebar and stiffening ribs increases the pull-out bearing capacity of the shear connector by 35%, while doubling the burial depth of the shear connector makes the pull-out bearing capacity increase by one time.

To investigate the friction and sliding performance of laminated-rubber bearings under aging conditions, heat aging tests and quasi-static tests were conducted based on the related provisions of shear aging resistance in the bearing specification. Firstly, the actual working state of the bearing in bridge engineering was simulated. Then, the bearing samples were subjected to hot air accelerated aging treatment through an aging chamber and then to horizontal cyclic quasi-static loading through a compression-shear machine. Finally, comparative analyses were conducted on the deformation state, hysteresis behavior, and related mechanical responses of the bearing specimens under different loading conditions. The results show that the shear deformation degree of the aged specimens is large during loading; the sliding degree is small, and the hysteresis loop is narrow and long. The sliding displacement of the bearings is negatively correlated with surface pressure and loading rate. The shear stiffness of the bearings first decreases and then increases as equivalent shear strain rises, and the shear stiffness of aged specimens decreases; the equivalent stiffness increases. At the average surface pressure of 10 MPa during the use of the bearings, there is less difference in the friction coefficient between the two types of specimens, both of which are lower than the recommended value of 0.20 in the specifications. The friction coefficient of the aged specimens is generally greater than that of unaged specimens, and insufficient energy dissipation is observed. There is a performance change point in the unaged specimens, and the overall mechanical behavior shows a three-fold trend. However, the friction and sliding behaviors of the aged specimens are stable, and there is no sudden change as the equivalent shear strain increases from 0 to 250%.

To reveal the mechanical properties of glacial tills in the Purang region of Xizang, in-situ direct shear tests with normal pressures from 100 kPa to 400 kPa were carried out on surface glacial tills in a natural state, and laboratory large-scale direct shear tests with normal pressures from 100 kPa to 400 kPa and large-scale triaxial tests with confining pressures from 100 kPa to 400 kPa were carried out on glacial tills with the compaction degree of 96%. The results show that the cohesion of surface glacial tills with a compaction degree of 91.7% is 11.0 kPa, and the internal angle of friction is 41.0°. The cohesion of glacial tills with a compaction degree of 96% is between 9.4 kPa and 11.2 kPa; the internal angle of friction is between 45.3° and 46.7°; the strength parameters obtained from laboratory large-scale triaxial tests are higher than those from large-scale direct shear tests. The peak strengths of glacial tills with a compaction degree of 96% are higher than those in a natural state, but the initial moduli are lower than those in a natural state. The stress–strain curve of glacial tills exhibits softening characteristics under various confining pressures, and the peak strain shows a trend of an increase followed by a decrease with the increase of confining pressures. The modified Duncan-Chang model can well describe the relationship between deviatoric stress and axial strain of glacial tills and reflect the strain softening characteristics of glacial tills in the Purang region.

As one of the important contents of health monitoring of concrete structure, crack detection reflects the stress and damage state of the structure, and the detection and evaluation is the core technology to ensure structure safety for service. The traditional detection methods have limited coverage in time and space and are greatly affected by environmental and altitude factors, so the detection efficiency and accuracy are relatively low. Additionally, they are dependent on subjective judgment, which is easy to cause missed detection and false detection. The detection method based on computer vision is equipped with digital imaging equipment for data acquisition, input, and image processing to automatically analyze and identify the concrete surface, which has the advantages of high efficiency, accuracy, and objectivity and is widely used in the field of intelligent crack detection of concrete structures. The principle, method, and application of concrete crack detection based on computer vision were described in detail from four aspects: image acquisition, image processing, recognition algorithm, and structure evaluation. Besides, the application of crack image acquisition equipment and various image preprocessing methods in digital imaging technology was reviewed comprehensively, and the advantages, disadvantages, and applicability of different recognition algorithms were analyzed. At the same time, the shortcomings of current research were summarized, and the challenges and problems faced by the application of computer vision technology for equipment intelligence and lightweight network were analyzed. Then the corresponding solutions were proposed. Prospects are also presented from the aspects of multi-source data fusion and utilization, lightweight intelligent equipment, digital imaging and crack mapping, and high-efficiency and real-time structure evaluation.

To study the mechanical constitutive model of steel bridge coating, uniaxial tensile tests were carried out on the long-lasting coating system, obtaining the stress–strain curves for the topcoat, intermediate coat, primer, and composite coating. The unified expression for the constitutive equation of the ascending segment of the long-lasting coating system was obtained through dimensionless processing, with corresponding constitutive equations provided for each coating film. The results are as follows. 1) The stress–strain curve for H06-X epoxy zinc-rich primer (80% zinc content) and long-lasting composite coating consists of an elastic and plastic stage, a strain-hardening stage, and a failure stage; the stress–strain curve for H06-C2 epoxy thick mica ferric oxide intermediate coat consists of a strain-hardening stage and a failure stage; the stress–strain curve for E01-JY fluorocarbon topcoat consists of an approximate linear elastic stage and a failure stage. 2) Based on the stress–strain curves, the mechanical property parameters of the primer, intermediate coat, topcoat, and composite coating, such as the elastic modulus, Poisson’s ratio, shear modulus, uniaxial tensile strength, and tensile fracture strain, are obtained. The primer shows the highest uniaxial tensile strength, followed by the intermediate paint, with the topcoat being the weakest. In contrast, the topcoat exhibits the best deformability, followed by the intermediate coat, with the primer showing the worst.

To optimize the T-shaped retrofitting scheme of diagonal members, the influence of structural and material parameters on the bearing capacity of the members after retrofitting was investigated through theoretical analysis, experimental study, and finite element analysis. Firstly, a theoretical model of the T-shaped retrofitting section was established based on the composite beam theory, so as to analyze the improvement in flexural stiffness after T-shaped retrofitting. Secondly, eccentric compression static experiments of single-side connected angle steels for T-shaped retrofitting were conducted. Finally, the finite element model was used to analyze the effects of the slenderness ratio, width-to-thickness ratio, and material strength on the selection of the number of connectors. The results indicate that the improvement in flexural stiffness after T-shaped retrofitting decreases with increasing load. A decrease in the number of connectors leads to relative slip perpendicular to the direction of member deformation. For the experimental members, an increase in the number of connectors leads to greater bearing capacity, with a maximum retrofitting effect of 100.4%. For the T-shaped retrofitting scheme of diagonal members, two connectors are sufficient when the slenderness ratio is below 150. Otherwise, three connectors are required. The width-to-thickness ratio and material strength have no effect on the selection of connectors.

To study the influence of automotive acoustic package design parameters on its multi-performance objectives, firstly, the traditional DBNs (deep belief networks) method was modified, and the SVR-DBNs (support vector regression-deep belief networks) model was proposed to improve the accuracy of model mapping. Secondly, from the perspective of vehicle noise transfer relationship and hierarchical target decomposition, a multi-level target prediction and analysis method was proposed. Finally, the proposed method was applied to the multi-objective prediction and optimization analysis of the MTL (mean transmission loss), weight and cost of the acoustic package for a real vehicle.The results show that the accuracy of SVR-DBNs method for the MTL, weight and cost target prediction of the acoustic package is higher than 0.975, which is better than that of the traditional BPNN（back propagation neural network）, SVR and DBNs models. The optimization results based on the SVR-DBNs model are appropriate to the measured results, the comprehensive relative error of the predicted and tested targets is 1.09% (the absolute values of the relative errors of MTL, weight and cost are 1.44%, 1.04% and 0.71%, respectively). Compared with the original status, the MTL, weight and cost of the acoustic package have increased by 5.51%, 9.01% and 4.40%, respectively.

With the increase in sinusoidal disturbance frequency, the performance of extended state observers (ESOs) will decrease. In order to improve the disturbance suppression ability of the ESO in the maglev rotor system, firstly, the mathematical model of a one-degree-of-freedom (1-DOF) maglev bearing rotor system was built. Secondly, ESO was designed, and the reasons for its reduced disturbance suppression effects were analyzed. On this basis, a model assisted ESO (MESO) was proposed to improve the bandwidth configuration and enhance the disturbance suppression effects. Then, the stability of the active disturbance rejection controller based on MESO was analyzed in the frequency domain. The effectiveness of the proposed observer was finally verified through simulation and experiments. The research results indicate that an increase in bandwidth amplifies the impact of system noises and increases the control voltage of the system. As the disturbance frequency increases, the suppression effect of MESO on high-frequency sinusoidal disturbance will decrease, but it can still reduce the modal amplitude of the rotor. After applying fundamental harmonic disturbance of 10 Hz−2 mm and fundamental impulse disturbance of 1 g to the rotor at a rotating frequency of 50 Hz respectively, the rotor displacement under MESO control is reduced by 16.3% and 22.6%, respectively compared with that under ESO control, and the control voltage is reduced by about 14%.