Abstract:【Objective】To ensure the vehicles through the work zone crossovers for expressway construction smooth and fast, a graded speed limit plan for the traffic control zone was studied.【Method】Firstly, collect and analyze the traffic flow velocity and time headway in different traffic control zones. Secondly, according to the vehicle trajectory to calculate the value of the last speed limit sign, and a graded speed limit plan for the traffic control zone was formulated based on vehicle deceleration and driver gaze. Finally, the graded speed limit plan was evaluated by safety and efficiency indictors through driving simulator.【Result】The results show that the average speed and the time headway in work zone crossovers are the smallest. When the median width is 70 m, the final speed limit value should be 40 km/h, forming a graded speed limit system in expressway construction with a deceleration amplitude of 20 km/h and a final speed limit sign positioned in 50 m before the upstream of the transition area.【Conclusion】The driving simulation test shows that compared with the two-level speed limit scheme in JTG H30—2015, the comprehensive efficiency index of the traffic control zone under established scheme has increased by 9.15%, and the extensive safety index has increased by 27.62%.

Abstract:【Objective】A crack detection method based on improved Unet model (A-Unet) is proposed to solve the problems of complex concrete cracks and many interference factors in bridges, tunnels and other environments. 【Method】Firstly, Unet-based network, how the deep of the encoder affects the training time and detection accuracy of the model is studied. Secondly, in the decoder process, a fusion space and channel attention module is designed to give different weights to the high-resolution shallow features and the deep feature information obtained from the upsampling to further enhance the crack features. At the same time, the dice loss function is added to evaluate the model to reduce the problem of inaccurate evaluation caused by the large difference between the number of detected objects and the background.【Result】The proposed method was evaluated in the test data set, the Precision, MIou and Recall rate reached 94.70%, 86.16% and 91.34% respectively. Also, the detection effect of A-Unet model is significantly better than the other five models.【Conclusion】The results show that the accuracy of concrete crack detection by this method is greatly improved, and the model training time is saved, and the detection efficiency is improved.

Abstract:【Objective】In order to investigate the initiation characteristics and propagation laws of fatigue cracks in the U rib-to-deck weld joints of a steel bridge deck under wheel loads。【Method】a segment model of steel bridge deck was established using the finite element method. Deformation characteristics of the structure were analyzed under different wheel load positions, and the correspondence between the wheel load position and typical deformation characteristics was clarified. Three local simplified models were then established accordingly. Using the local models, the crack initiation characteristics were determined based on stress distribution and three-dimensional numerical simulation of crack propagation was carried out based on fracture mechanics.【Result】The results show that under the deck dominated deformation condition, the maximum principal stress at the weld toe and root of the deck is significantly greater than that at the weld toe of the U-rib, and strength factor Ⅰ is much higher than Ⅱ and Ⅲ after crack generation; Under the condition of U-rib dominated deformation, the maximum principal stress at the weld root of the deck and the weld toe of the U-rib is perpendicular to the thickness direc-tion of the U-rib, and Ⅱ and Ⅲ account for 20% ~30% of Ⅰ.【Conclusion】When the wheel load in the real bridge deviates from the weld, the fatigue crack tends to initiate at the weld root and weld toe of the deck and propagates along the thickness direction of the deck, with the crack extension type being mode Ⅰ. When the wheel load is located directly above the weld, the fatigue crack prefers to initiate at the weld root of the deck and the weld toe of the U-rib, propagating obliquely perpendicular to the U-rib web. These cracks belong to the Ⅰ-Ⅱ- Ⅲ composite type, and their propagation rate is faster.

Abstract:【Objective】As a new type of strain measuring instrument, fiber bragg gratings (FBG) strain sensors are gradually used in the field of civil engineering, and the key to their use lies in the deployment of sensors and the calibration of sensitivity coefficients according to different usage requirements and environments. The current conventional FBG installation methods are direct surface adhesion and slotting implantation.【Method】In order to determine the measurement accuracy of the two installation methods, a calibration method of the unpacked FBG sensitivity coefficient used for the pile sinking test was proposed and the calibration test of the two deployment methods was carried out by using the circular seamless steel tube as the matrix, and the calibrationresults were compared with the theoretical values.【Result】The results show that in the stage of progressive loading, the calibration coefficient obtained by slotting implantation is smaller than that by surface adhesion，while the calibration coefficient obtained by the surface adhesion is closer to the theoretical value. The calibration coefficients obtained by slotting implantation and surface adhesion were 2.84% and 0.33% respectively compared with the theoretical values; In the step-by-step unloading phase, there is a certain lag in the central wavelength of the two deployment methods, but the calibration coefficient is not much different from that inthe loading stage.【Conclusion】Therefore, it is necessary to choose a reasonable fiber grating layout scheme and calibration method according to the test environment and within the test tolerance range in the process of using FBG.

Abstract:【Objective】Recycled ceramic fine aggregate was used to replace natural river sand with a quality of 0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100% replacement rate to create recycled ceramic fine aggregate concrete (CRFC) to investigate the effects of various types and replacement rates of recycled ceramic aggregate on the compressive strength and modulus of elasticity of concrete.【Method】To create recycled ceramic coarse and fine aggregate concrete (CRC), natural gravel was substituted based on the replacement rate of recycled ceramic fine aggregate (100% ) with natural fine aggregate. The physical and mechanical properties of CRFC and CRC were investigated, as well as the viability of using wasted tile ceramics as recycled concrete aggregate.【Result】The results show that: The workability, compressive strength, and elastic modulus of CRFC made with recycled ceramic fine aggregate are similar to those of normal concrete. As the replacement rate of recycled ceramic coarse aggregate increased, the compressive strength and elastic modulus of CRC dropped dramatically.【Conclusion】Waste ceramic bricks can be utilized as coarse and fine aggregate in concrete preparation. To ensure concrete workability while utilizing recycled ceramic coarse aggregate, additional water should be supplied by its water absorption rate. The bond strength in the interfacial transition zone and coarse aggregate type are the main factors influencing the failure patterns of CRFC and CRC, respectively. It is suggested that the replacement rate of recycled ceramic coarse aggregate is less than 50% when natural fine aggregate is totally replaced by recycled ceramic fine aggregate.

Abstract:【Objective】In order to explore the distribution law of crystallization blockage in tunnel drainage system under the action of groundwater seepage, a laboratory simulation test of crystallization law of EmeishanHanyuan high-speed tunnel drainage system was put forward.【Methods】Based on the Liaoshan tunnel project of Emeishan-Hanyuan High-speed, a 1∶5 indoor simulation test of tunnel drainage system was established, and a test solution with the same ionic composition was configured according to the analysis results of in-situ groundwater sampling.【Result】The crystal stacking mode is mainly a large amount of stacking, which belongs to the isomeric crystal type, and the main component is calcite type calcium carbonate; With the increase of water flow, the crystallization amount increases, and the crystallization rate is faster, among which, the cumulative total crystallization under the condition of 266.8 mL/s water flow at the lateral drainage outlet is the highest; The moderate slope of the drainage pipe is conducive to the formation of crystals in the tunnel drainage pipe; The total amount of crystallization at the drainage pipe joint (30%) ＞ horizontal drainage outlet (27%) ＞ horizontal drainage pipe (19%) ＞ vertical drainage pipe (15.2%) ＞ circumdirectional drainage pipe (8.3%). The key positions of crystallization blockage in the tunnel drainage system are the drainage system interface and horizontal drainage pipe outlet.【Conclusion】The distribution law of crystal blockage in drainage pipe is effectively analyzed, which is of great significance for ensuring smooth and effective operation of tunnel drainage system.

Abstract:【Objective】In order to improve the poor anti-interference ability, sensitivity to parameter changes, and high harmonic content of the PETT rectifier stage under traditional dq current decoupling double closed-loop control in order to improve the problem.【Method】By improving the decoupling method of DPC, a power decoupling controller based on ADRC was proposed, without requiring system angular frequency and inductance parameters. Finally, a model was built in Matlab/Simulink for simulation analysis under different operating conditions.【Result】The simulation results showed that the new control strategy reduced the THD value of the grid side current by 5.38% compared to the traditional control strategy, reduced the voltage drop value by 48 V when the equivalent induct-ance suddenly changed, and reduced the voltage drop value by 14 V when the voltage frequency shifted.【Conclusion】This controller achieves precise and independent control of active and reactive power through decoupling. The new control strategy has good balance control effect under load sudden change and load im-balance conditions. The simulation results verify the rationality and effectiveness of the proposed control strategy

Abstract:【Objective】In order to solve the difficulties such as small target feature extraction, a transformerbased traffic sign detection model was proposed.【Method】Through fully utilizing the advantages of convolution and Transformer, a multi-scale feature extraction backbone model was established with attention fusion, which could enable the backbone network to selectively enhance the features of useful information and suppress the unimportant ones with the support of global context information. In addition, pooling-like connection are incorporated in order to prevent network degradation while enhancing feature fusion. Finally, experiments were conducted on the TT100K dataset.【Result】The experimental results show that the meta-architecture with this model as the backbone achieves the highest mAP of 84%, and the maximum improvement of mAP is about 7% compared with the baseline model.【Conclusion】The model provides a new idea for traffic sign detection while improving feature extraction.

Abstract:【Objective】With the rapid growth of various mobile applications and services, the contradiction between the battery capacity and the energy consumption at mobile terminals is becoming increasingly prominent. In addition, the ultra-dense deployment of small base stations (SBSs) in ultra-dense network (UDN) makes network interference more complicated, and servers deployed at the edge of the network are also vulnerable to malicious attacks.【Method】By jointly optimizing the user equipment (UE) association, cryptographic service assignment, UE power control, and computational resource allocation of UEs and SBSs, the sum of weighted standardized total energy consumption and standardized total security cost is minimized for the multi-task UDN. Specifically, mobile edge computing (MEC) and local computing models are first built for multi-task UDN. Then, a further improved hierarchical adaptive search (FIHAS) algorithm is designed for a problem with minimizing the sum of weighted normalized total energy consumption and normalized total safety cost. 【Result】In the simulation, FIHAS can obtain lower weighted sum than other algorithms and has an advantage in reducing total cost. 【Conclusion】In general, FIHAS may achieve the better system performance than other algorithms.

Abstract:【Objective】In order to address the lack of data support for passenger flow forecast of railway stations at the initial stage of operation, as well as the significant deviation between the roughly calculated passenger flow transfer of different transport modes considering the costs of different modes and the actual situation. 【Method】This paper takes the newly opened Jiangyin Station of the South Riverside Intercity Railway as an example, considering the location relationship between the line and the existing high-speed and intercity railways, based on the intercity trip chain, and relying on the passenger travel behavior survey to quantitate the intercity trip utilities of different transportation modes. Combined with the current passenger flow assignment and distinguishing workdays and non-workdays, the Multinomial Logit (MNL) model is established for calibrating the co-efficients of utility variables. Accordingly, the passenger flows from Jiangyin Station on the South Riverside Intercity Railway, the passenger flows to Nanjing and Shanghai terminals were predicted, to other stations along the line were also calculated deductively in combination with the economic and social developments of the cities along the line.【Result】The results show that the opening of Jiangyin Station can effectively attract the passenger flows in Jiangyin area who originally chose the existing railways and highways to Nanjing and Shanghai, as well as the passenger flows that chose the highways to other cities along South Riverside Intercity Railway. 【Conclusion】Therefore, the opening of South Riverside Intercity Railway can effectively relieve the transportation pressure of existing railways and highways in the region, and the passenger flow forecast results also supports the optimization of station resource allocation.

Abstract:Drivers are affected by traffic stress events during driving, in order to explore whether driver characteristics affect driver’s stress response. 21 subjects from high driving characteristics group (Group H) and low driving characteristics group (Group L) were selected by the Wiener Traffic Psychometric test system (VTS) to analyze the stress response characteristics of different driving groups through statistical methods, and the set pair analysis model was used to evaluate the stress response of the subjects. The specific performance is as follows: it is feasible to distinguish driver’s stress response ability by detecting driver characteristics. Improving driving characteristics can help drivers enhance their stress ability. The more critical the situation is, the greater the improvement is. In all stress distance experimets, stress response of Group H is better than that of Group L and the reduction of stress distance had a greater impact on Group L than on Group H. The results prove that it is necessary to provide drivers with more than 1s TTC (time to collision) in traffic stress events.

Abstract:【Objective】Aiming at the problem of charging state balance management of lithium battery, a multiAgent based battery pack consistent charging state balance scheme was proposed.【Method】Firstly, the multiAgent control strategy is introduced into the sagging control of battery management, and the autonomous balancing under the active balancing circuit topology was realized. Secondly, the lead follower model is established, and the virtual agents with known parameters are used to make the state of each battery with inconsistent charging state close to it, so as to achieve the charging state balance in charge-discharge mode. Finally, simulation verification of the two-order multi-Agent state load balancing control strategy is carried out.【Result】The experimental results show that, compared with the first-order balancing control strategy, the autonomous balancing time is reduced by 43.02%, the balancing time in charging mode is reduced by 16.13%, and the balancing time in discharge mode is reduced by 32.90%.【Conclusion】The multi-Agent system can achieve the balance of SOC in battery balancing management, effectively reducing the convergence time of SOC reaching the consistency of lithium battery.

Abstract:【Purpose】A detection algorithm is proposed to address the issue of low detection efficiency of highspeed railway contact line insulators in complex backgrounds.【Methods】On the basis of the original YOLOv5s algorithm, in order to effectively improve the representation power of the model and increase the ECA attention mechanism, a cross-channel method without dimensionality reduction is carried out to focus on the position information of insulators. The BiFPN feature pyramid network is used to enrich the semantic information by multiscale feature fusion. The Meta-ACON adaptive control activation function is selected and the upper and lower limits of the function is strictly controlled within the maximum range allowed by the function to prevent the model from running out of control. The original GIOU loss function is replaced with the EIOU loss function, and the anchor box is further divided from the perspective of gradient, so as to improve the convergence speed of the network.【Results】Acoording to the experimental results, the improved detection algorithm of YOLOv5s can be used to locate and identify the insulator more accurately, and the accuracy rate reaches 99.4%.【Conclusion】The proposed detection algorithm provides a more accurate and faster method for insulator positioning detection.

Abstract:【Objective】The MR-DCA based rolling bearing fault diagnosis method is proposed for the problem that rolling bearing weak faults are difficult to identify.【Method】The input samples are pre-processed by using the maximun correlated kurtosis deconvolution and resonance-based sparse signal decomposition, which can effectively filter out the noise of original signal and feature the fault impact components. The obtained two-dimensional time-frequency diagrams of the fault components and the original signal are used as the training samples of the network, and after two feature learning modules, the input features are filtered by using the attention mechanism, and the model computational efficiency and recognition accuracy can be effectively improved through weight reassignment. In order to verify the model performance, a rolling bearing weak fault dataset is used for fault diagnosis analysis, while ablation experiments are carried out to verify the effectiveness of each module of the diagnostic model.【Result】The results show that the proposed method has higher recognition accuracy, faster training speed and faster iteration speed.【Conclusion】The proposed model can achieve good diagnostic performance in the diagnosis of rolling bearing weak faults.

Abstract:【Objective】In recent years, constructed wetland (CW) coupled with microbial fuel cell (MFC) have formed a novel bioelectrochemical system, constructed wetland-microbial fuel cell (CW-MFC), with excellent pollutant degradation and bioelectricity generation performance. The aim of this paper is to summarise the characteristics and applications of the electrodes, introduce the effects of different electrode materials on the system, and finally provide an outlook on its future research directions.【Methodology】This paper combines the latest research results at home and abroad.【Results】The functional properties and applications of electrodes are summarised, followed by the performance differences of different electrode materials in the wastewater treatment process and their effects on the power generation efficiency, and finally an outlook on their future research directions is presented for further reference for the technological development of CW-MFC.【Conclusion】CW-MFC is a bioelectrochemical system with a wide range of applications. Future research directions include optimisation of electrode materials, improvement of system operation efficiency and cost reduction. At the same time, research in practical applications needs to be strengthened to promote the application of this technology in the fields of environmental protection and energy.