Abstract:【Objective】In order to recover the mechanical energy during the vibration of the vehicle suspension, a vibration mechanical energy recovery is conducted based on the designed vibration energy harvesting magnetorheological (MR) damper and charging circuit module. 【Method】The proposed vibration energy harvesting MR damper is modeled for power generation performance based on COMSOL software, and the charging capability for 1.2V lithium battery is also analyzed combined with Simulink for co-simulation. The full-bridge rectifier circuit is designed and fabricated, and the experimental test system is also built. The generating electricity abilities of the induction coils in series are tested under the sinusoidal displacement excitation with frequency of 4Hz and amplitude of 8mm. 【Result】The test results show that the induction coils in series can generate power of 0.13W, and it is lower than the simulated value of 0.22W. The reason is that the mechanical vibration energy is relatively weak and there exists circuit loss. In addition, the charging energy from the damper to the 1.2V lithium battery is about 1.2mAh within 40s, and it needs 1667s to fully charging. 【Conclusion】The relevent results show the developed MR damper has a good charging ability.

Abstract:【Objective】Aiming at the problems of highway pavement distresses, such as the existence of many categories, large scale differences and high background complexity, a highway pavement distress detection algorithm with improved YOLOv7 is proposed.【Method】Firstly, the display visual center module EVC is introduced into the neck network to fully obtain the global and local information of the input features and improve the feature extraction ability for small targets; secondly, the feature fusion module RFECSP is designed to enhance the feature fusion ability for multi-class and multi-scale lesions, and to solve the problem of the loss of detail information and the influence of irrelevant regions that lead to the low detection accuracy; finally, the MPDIoU loss function is used to improve the network. MPDIoU loss function to improve the convergence speed and detection accuracy of the network.【Result】The experimental results show that the algorithm in this paper achieves good results on the RDD 2020 dataset, improves the average detection accuracy by 3.13% compared with the YOLOv7 algorithm, and outperforms the algorithms such as SSD, YOLOv4, YOLOv5, etc.【Conclusion】The algorithm in this paper has a good effect of detecting pavement diseases, and is able to satisfy the requirements of detecting different types of diseases on highway pavements.

Abstract:[Objective] In order to meet the requirements of vehicle load modeling and analysis for the digital transformation of highway and bridge, [method] the characteristics of vehicle load are analyzed and summarized. Based on the classification method of the number and complexity of random factors, vehicle load models are divided into single factor vehicle load model, vehicle load spectrum, random traffic load model and vehicle load theoretical model. Based on this classification, the characteristics, modeling methods, development status, existing problems and application prospects of various vehicle load models are discussed. [result] The results indicate that existing vehicle load modeling methods mostly rely on sampling analysis of unknown random processes, which are often inefficient and limited, and the resulting load models are not universal; In practical applications, appropriate modeling methods should be selected based on the characteristics of single factor vehicle load models, vehicle load spectra, and random traffic load models to meet application requirements; The random traffic load model is currently the most comprehensive modeling description of vehicle loads, and its basic research direction focuses on covering more load parameters, clarifying the correlation between various parameters, and more efficient modeling methods; The development of vehicle load theoretical model is not mature, which is the main direction of further research on vehicle load. [Conclusion] With the development of society, the establishment of universal and automatic vehicle load model has become the basic trend of model development.

Abstract:【Objective】 Stratified rock is a common sedimentary rock type in underground engineering environment, and the rock bolt support technology is widely used to strengthen the stratified surrounding rock in order to study its mechanical response under complex engineering stress environment. 【Method】 Yunnan red sandstone, marble glue, screw and epoxy resin were selected as raw materials. Triaxial compression tests were conducted to investigate the effects of different interfacial dip angles and confining pressures on the mechanical properties of anchored and unanchored stratified rocks. 【Results】 The results showed that the failure of the sample went through the stages of pore compaction, elastic deformation, crack development and macroscopic crack generation, and its strength, deformation parameters and crack growth morphology were significantly affected by confining pressure. The increase of confining pressure can prolong the elastic deformation stage and improve the residual strength and ductility. The failure modes of specimens with different angles under confining pressure are split failure, tensile shear failure and pure shear failure. 【Conclusion】 This study provides strong support for further understanding of rock mechanical properties and engineering applications.

Abstract:In the current domain of air traffic, frequent flight conflicts and departure flight delays within airport systems are increasingly becoming key factors that affect the efficiency of flight operations and passenger satisfaction. In light of this, the present study aims to explore the collaborative sequencing problem of departure flights within airport systems. By considering the resource constraints of airport systems, the concept of "departure flight satisfaction" is introduced. The objectives of optimization include minimizing the total delay of departure flights, maximizing the sum of average satisfaction across all flights in airports, and minimizing the overall measure of fairness within the airport system. A collaborative sequencing model for departure flights in the terminal area of airport clusters is established, and an elitist strategy-based non-dominated sorting genetic algorithm is designed to solve the Pareto optimal solution for the collaborative sequencing problem of departure flights in the terminal area of airport clusters. An empirical analysis was conducted using the terminal areas of three airports in the Beijing-Tianjin region as examples, validating the effectiveness of the proposed model and method. The experimental results show that compared to the first-come-first-served scheme, the total flight delay was reduced from 7,796 seconds to 5,029 seconds, a decrease of 35.3%, with the average delay per flight dropping from 159 seconds to 103 seconds. The average satisfaction of flights reached 0.7867, and the overall measure of fairness among airports in the cluster was 0.0044. The proposed optimization method can significantly reduce the total delay of departure flights in airport systems, improve overall flight satisfaction, and achieve the fair and efficient use of resources.

Abstract:【Objective】To delve into the temperature effect of sustained summertime heat on the bridge-mounted CRTS III type ballastless track, this research aims to offer scholarly guidance for the enhancement of seamless track line design, operational maintenance, and remedial strategies for bridge-mounted ballastless track systems.【Method】Based on the principles of thermodynamics and the mechanics of beam-slab-rail interaction, a refined thermo-mechanical coupling model for the bridge-mounted CRTS III type ballastless track seamless lines has been established to simulate the temperature field, longitudinal forces, and displacement variations of the track structure components under sustained high-temperature conditions ranging from 2 to 10 days.【Results】

Abstract:【Objective】Studying the issue of excessive vibration in high-rise buildings located in the test track area of subway depots.【Method】Through on-site measurement and finite element simulation of the environmental vibration before and after the vibration reduction transformation of a subway vehicle testing line, the vibration source and the vibration transmission law of the upper cover before and after the vibration reduction transformation are analyzed.【Result】The results indicate that the influence of vehicle speed on the dominant frequency of the source intensity affects the level of vibration transmitted to various floor slabs. The vibration measured in bedrooms is relatively large under the condition of 60km/h, while the vibration in living rooms is more significant under the condition of 40km/h. The vibration first decreases, then increases, and finally decreases again as the distance from the vibration source increases. While the steel spring floating slab reduces vibration, noise may be slightly amplified, with all vibration measurement points at the vibration source reduced by more than 10dB after the modification, but the noise at the 7.5m measurement point increased by 0.96dB. By comparing and observing the changes in vibration levels at different frequencies with floor height before and after the vibration reduction modification, it is found that the maximum frequency band of vibration acceleration level shifts forward, from 25-40Hz before the modification to 20-25Hz after, which is related to the change in excitation frequency at the vibration source.【Conclusion】Compared to conventional ballast beds, the steel spring floating slab after vibration reduction modification can significantly reduce vibrations, enabling the buildings constructed above the test track area of this depot to meet the corresponding regulatory requirements.

Abstract:【Objective】The impact of high-speed trains on urban green technology innovation is an important research direction in the study of the impact of high-speed trains on regional innovation. In order to study the impact of high-speed railway on the "quality and quantity" of urban green technology innovation, 【Method】this paper establishes a multi-period DID model and discusses how high-speed railway operation affects urban green technology innovation based on the panel data of 41 cities in the Yangtze River Delta urban agglomeration from 2004 to 2019. 【Result】The results show that the operation of high-speed trains can effectively improve the "quality and quantity" of urban green technology innovation in the Yangtze River Delta. Through the mechanism test, the opening of high-speed trains can affect urban green technology innovation by strengthening economic agglomeration and venture capital; The operation of high-speed trains has the heterogeneity of city size and region, and the operation of high-speed trains has a significant impact on large cities and small and medium-sized cities. 【Conclusion】This study systematically expounds the connection between the operation of high-speed trains in the Yangtze River Delta region and the "quality and quantity improvement" of urban green technology innovation, and the conclusion is still valid after the robustness test.

Abstract:【Objective】To compare and analyze the resilience of route networks in terminal areas of different airports within an airport cluster. 【Method】This study uses the Guangzhou terminal area and the Zhuhai approach terminal area as examples, applying complex network methods to construct route network models for each. The network topology is analyzed in detail using indicators such as node degree, degree distribution, betweenness centrality, clustering coefficient, network diameter, and average path length. Based on this analysis, node importance is identified using degree centrality, betweenness centrality, and the KBKNR algorithm. Additionally, scenarios of random attacks and deliberate destruction are designed, and network efficiency and connectivity are used as metrics to evaluate the resilience of the route networks.【Results】The experimental results show that under random attacks, the Zhuhai Terminal Approach Air Route Network demonstrates greater resilience compared to the Guangzhou Terminal Air Route Network. Conversely, under intentional attacks, the Guangzhou Terminal Air Route Network exhibits stronger resilience. Moreover, degree centrality attacks are more likely to cause network collapse compared to betweenness centrality attacks, indicating that nodes with high degree centrality should be prioritized for protection as critical nodes.【Conclusion】This study can help identify critical waypoints or air routes and implement corresponding protection measures, thereby improving the operational efficiency of flights in terminal areas.

Abstract:【Objective】To investigate the dynamic response of reinforced concrete columns under impact, 【Method】relying on the two-degree-of-freedom mass-spring-damper model and combining with the OPENSEES computing platform, on the basis of clarifying the equivalent resistance-displacement curve of reinforced concrete columns, a simplified impact analysis method for reinforced concrete columns integrating material nonlinearity and impact strain rate effects is proposed. By comparing with the drop hammer impact test of reinforced concrete columns, the validity of the proposed two-degree-of-freedom simplified analysis method is verified. On this basis, the impacts of sensitive parameters like impact velocity, impact mass, axial compression ratio and longitudinal reinforcement ratio on the drop hammer impact response of reinforced concrete columns are explored. 【Result】The results showed that the peak impact force calculated by the proposed simplified analysis method has a deviation of approximately 4.30% from the test value, and the deviation of the peak displacement at mid-span is approximately 2.16%. With the increase of the impact velocity and impact mass, the peak impact force and the peak displacement at the mid-span of the column gradually increased, but the increase of the impact velocity and impact mass would lead to a delayed characteristic of the peak displacement at the mid-span of the column. With the increase of the axial compression ratio and the longitudinal reinforcement ratio, the peak impact force of the column gradually increased, while the peak displacement at the mid-span showed a gradually decreasing trend. Moreover, the change of the longitudinal reinforcement ratio had a significantly greater influence on the secondary impact in the impact force time history curve than the change of the axial compression ratio. 【Conclusion】The proposed simplified analysis method can accurately predict the impact dynamic response of reinforced concrete columns