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Real-Time Template Matching Method for Edge Features WANG Shiyong, QIAN Guokang, LI Di, et al. Journal of South China University of Technology(Natural Science Edition)    2023, 51 (9): 1-10.   DOI: 10.12141/j.issn.1000-565X.220745 Abstract （656）   HTML （21）    PDF（pc） （5488KB）（2058）       Knowledge map    Save Template matching is a common key technology in the field of machine vision. Currently, edge feature-based template matching methods are facing challenges such as time-consuming searching and low matching accuracy in a complex environment. In order to ensure the robustness while improving the real-time performance, this paper proposed a real-time edge feature-based template matching method. Firstly, in the stage of template creation, a new edge sparse method was proposed, and it can screen out the strong invariant edge points from the template image. It reduces the redundancy of template information while retaining the key template features to ensure the stability and improve the computing efficiency. Secondly, in the stage of pyramid search-based image-matching, a top-level pre-screening method was proposed. Normalized Manhattan distance was used as a constraint to exclude incorrect target poses from the top search results to speed up the search in subsequent layers. Five datasets with different working conditions were constructed, and the proposed template matching method was compared and applied to the fast visual dispensing process for free plane pose. The experimental results show that the proposed matching method can significantly improve the matching speed while ensuring high accuracy. And it can overcome interference factors such as illumination change, rotation, defects, multiple targets, and occlusion, enabling practical applications that require both high robustness and real-time performance. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Operational Reliability Optimization Strategies of Multi-type Bus Lines ZHAO Xiaomei, ZHU Xiangyuan, WANG Qin, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (8): 32-39.   DOI: 10.12141/j.issn.1000-565X.220493 Abstract （1465）   HTML （32）    PDF（pc） （894KB）（1351）       Knowledge map    Save The unstable running time and the difficulty to accurately estimate the arrival time reduce passengers’ satisfaction with bus traveling. With the diversification of cities, bus line types are gradually becoming more diverse, and the variations in bus operating time of the various bus line types cause trouble in bus scheduling and inconvenience for passengers. To solve above problems, firstly, this paper used K-means ++ algorithm to cluster the stations with the sum of squares of error (SSE) as the measurement index. The operation characteristics and reliability influencing factors of different types of bus lines were taken into consideration to determine the alternative station sets of limited-stop bus service. Then, a joint optimization strategy model of limited-stop bus service and speed regulation was proposed to determine the limited-stop bus station, the departure time, and the running speed of all buses. This model took the minimization of bus operation cost, passenger travel cost, and reliability cost as the objectives, and took the constraints of operation process and headway of limited-stop bus service and all-stop bus service into consideration. Finally, genetic algorithm was used to solve the optimization model and Beijing bus system was selected for case analysis. The results show that the limited-stop bus service can reduce the operation cost of public transport, the speed regulation strategy can better lower the passenger travel cost and reliability cost, and the joint optimization strategy of limited-stop bus service and speed regulation can effectively reduce the total cost of the bus system. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Optimized Design of the Main Structure of a Wall-Climbing Robot for Bridge Detection Based on Negative Pressure Adsorption HUANG Haixin, WANG Zheng, CHENG Shoushan, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (12): 21-33.   DOI: 10.12141/j.issn.1000-565X.220695 Abstract （342）   HTML （8）    PDF（pc） （5565KB）（1218）       Knowledge map    Save To address the challenging task of inspecting hard-to-reach areas, such as high piers and the bottom of bridges, the paper developed a wall-climbing robot for bridge disease detection based on negative pressure adsorption. For the robot’s own adsorption stability, this paper established and derived a formula for calculating the adsorption force index under conditions of anti-slip and anti-overturning, based on which the minimum adsorption force required by the robot to achieve stable wall adsorption at all angles was determined. The results show that to ensure the reliable operation of the robot, the adsorption module needs to provide 53.0 N adsorption force. The preliminary design of the centrifugal impeller was formulated based on empirical principles, followed by fluid mechanics simulation and response surface optimization of the impeller basin using Fluent. An evaluation function, comprising adsorption force and torque, was established to optimize the impeller design parameters to maximize the comprehensive evaluation function value of the adsorption module. Compared to the initial design scheme, the optimized design achieved a 3.4% increase in the evaluation function value while maintaining stability. Taking into consideration the aerodynamic performance of the chamber along with the topology optimization results, topology optimization of the negative pressure chamber was performed. The structure and arrangement of reinforcing ribs inside the chamber were obtained, with the reinforcing ribs connected to the wheel support arm designed in “八”-shaped and linear hollow structures. This optimization reduced the maximum vertical displacement of the negative pressure chamber to 18.5% of the original model, with a minimal increase in mass of 16.9%. It shows that the precise layout effect of the strengthening rib is obvious, and the vertical deformation is successfully controlled within a reasonable range. Finally, a prototype was constructed using UTR6180 photosensitive resin and 3D printing technology, with approximate dimensions of 300 mm×280 mm×15 mm and a mass of approximately 1.15 kg. The performance test of the prototype was conducted under various working conditions, demonstrating that the wall-climbing robot can stably adsorb and move on various bridge walls without slipping or drifting. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Stuby on the Activity Patterns and Regularity of Public Transport Passengers CHEN Yanyan, WANG Zifan, SUN Haodong, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (8): 40-50.   DOI: 10.12141/j.issn.1000-565X.220658 Abstract （592）   HTML （17）    PDF（pc） （2146KB）（1179）       Knowledge map    Save In order to explore the activity pattern and regularity of public transport passengers, this study constructed multi-day passenger travel activity sequences using three weeks smart card data in Beijing in October 2020. The frequent activity pattern sequences of passengers were mined through the PrefixSpan algorithm, and the similarity measure method of activity patterns was defined based on the longest common subsequence. The day-to-day activity sequence similarity of individual and activity pattern similarities among different passengers were calculated respectively, and passengers were classified according to activity pattern similarities among passengers by using the hierarchical clustering algorithm. The results show that the similarity between workdays and weekends is significantly lower than that within workdays or weekends. In workdays, the activity sequence similarity between Friday and the other days is low. Meanwhile, the activity sequence similarity of the same days in different weeks is high. The result of hierarchical clustering shows that there are four typical activity patterns, including entertainment and shopping orientation, life orientation, work orientation and personal affair orientation. Moreover, the day-to-day activity sequence similarity of passenger with work orientation pattern is higher than that of passenger with other activity patterns. The research results in this paper are helpful to scientifically formulate accurate public transport operation management and service policies. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Graph Neural Network for Fault Diagnosis with Multi-Scale Time-Spatial Information Fusion Mechanism ZHAO Rongchao, WU Baili, CHEN Zhuyun, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (12): 42-52.   DOI: 10.12141/j.issn.1000-565X.220593 Abstract （1503）   HTML （5）    PDF（pc） （4157KB）（1141）       Knowledge map    Save Due to the long-term operation of planetary gearboxes in strong noise environments and changing working conditions, the collected vibration signals exhibit weak fault characteristics and variable signal patterns, making them difficult to identify. Intelligent fault diagnosis of planetary gearboxes under these conditions remains a challenging task. In order to achieve high diagnostic accuracy and strong model generalization performance, a fault diagnosis method using a graph neural network with a multi-scale time-spatial information fusion mechanism is proposed. The method first uses convolution kernels of different scales to extract features from the original vibration signal, reducing the masking effect of strong noise signals on valuable information and enhancing its feature expression ability. A channel attention mechanism is then constructed to adaptively assign different weights among different channels to features of different scales, enhancing features in segments of information containing crucial fault characteristics. Finally, the multi-scale features of the convolution module output are used to construct graph data with spatial structure information for graph convolution learning. This approach allows for the full utilization and deep fusion of multi-dimensional time domain information and spatial correlation information, effectively improving the accuracy of diagnosis and the generalization performance of the model. The proposed method was verified using a fault dataset of wind power equipment with planetary gearbox structure. The average diagnosis accuracy of the proposed method was found to reach 98.85% and 91.29% under cross-load and cross-speed conditions, respectively. These results are superior to other intelligent diagnosis methods, including deep convolutional neural networks with wide first-layer kernels (WDCNN), long short-term memory network (LSTM), residual network (ResNet), and multi-scale convolution neural network (MSCNN). Therefore, the strong generalization performance and superiority of the proposed method were confirmed. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Evolution of Interface Performance of Longitudinal Ballastless Track Under Temperature Load After Embedded Steel Bars LU Hongyao, XU Yude Journal of South China University of Technology(Natural Science Edition)    2023, 51 (8): 21-31.   DOI: 10.12141/j.issn.1000-565X.220735 Abstract （452）   HTML （14）    PDF（pc） （5162KB）（1030）       Knowledge map    Save In order to clarify the performance evolution of the interlayer interface of the longitudinal slab ballastless track under the temperature load, this study carried out the mechanical and fatigue performance tests of the interface after embedded steel bars of the composite specimen, and the load spectrum was generated by combining the temperature field monitoring data of the track slab on site.The spatial refined finite element model of ballastless track considering the whole process of interface damage was established and the stress state and damage characteristics of the interface between the lower layers under adverse temperature load were analyzed. The concept of initial temperature load of interface damage was introduced.The change in temperature load at the onset of damage at the interlayer interface after embedded steel bars was calculated and the evolution of debonding risk time after structural performance degradation was clarified. The results show that bearing capacity of the interlayer interface embedded with steel bar is significantly improved.The critical debonding failure displacement and the maximum load are increased by 76.38% and 153.41% respectively, and the fatigue performance is better, indicating that it is feasible to reduce the risk of interfacial debonding of ballastless track through embedding steel bars. The anchoring of embedded steel bars can not fundamentally limit the transmission of temperature force in the ballastless track and the damage suppression effect at the boundary of the slab is limited. It is easy to cause hidden damage near the reinforcement planting hole and the maximum damage value can reach 0.944. With the increase of service life,the initial temperature load that causes the initial damage of the interlayer interface decreases continuously. The safe temperature change range of good bonding state of the interface is reduced from 30.3 ℃ to 16.3 ℃.The number of days with possible interface damage risk is increased by 64.29% and the interlayer interface may have been damaged before extreme weather occurs.The railway department needs to adjust the temperature range of the concerned board based on the actual development of line diseases, and dynamically adjust the setting standards for maintenance thresholds. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Axial Compression Behavior of Rectangular Concrete-Filled Steel Tube Columns Reinforced by Built-In Profiled Stirrup KANG Lan, CHEN Xuan, HONG Shutao Journal of South China University of Technology(Natural Science Edition)    2024, 52 (5): 101-113.   DOI: 10.12141/j.issn.1000-565X.230116 Abstract （189）   HTML （3）    PDF（pc） （4333KB）（511）       Knowledge map    Save Concrete-filled steel tube (CFST), as a kind of structure with broad development prospect, has good bearing capacity and plastic deformation ability. As a common form, rectangular concrete-filled steel tube column is widely used in engineering practice. Based on the two problems of inconsistent constraints on long and short sides and insufficient constraints on core concrete existing in practical application of rectangular concrete-filled steel tube, this study explored a new type of rectangular concrete-filled steel tube member, namely rectangular concrete-filled steel tube column reinforced by built-in profiled stirrup. Therefore, this study carried out the axial compression tests on 11 rectangular concrete-filled steel tube columns reinforced by built-in profiled stirrup, 2 rectangular concrete-filled steel tube columns with built-in racetrack stirrup, and 2 ordinary rectangular concrete-filled steel tube columns. It analyzed the influences of the coupling distance, steel tube thickness, concrete strength grade, stirrup spacing, stirrup diameter, built-in steel quantity on the axial compression bearing capacity and ductility of rectangular concrete-filled steel tube columns reinforced by built-in profiled stirrup. The findings reveal that reducing the thickness of the rectangular steel tube and embedding the resulting steel into the core concrete as profiled stirrup can effectively improve the axial compressive bearing capacity and ductility of the specimen, while maintaining the total amount of steel used. Additionally, the axial compression behavior of rectangular concrete-filled steel tube columns reinforced by built-in profiled stirrup can be divided into four stages: elastic stage, elastoplastic stage, plastic strengthening stage, and descending stage. Compared to ordinary rectangular concrete-filled steel tube columns, those reinforced by built-in profiled stirrup exhibit a more complete plastic strengthening stage. Based on the experimental results and parametric analysis, this study derived a calculation formula for the axial bearing capacity of rectangular concrete-filled steel tube columns reinforced by built-in profiled stirrup using an existing confined concrete constitutive model. This study can provide scientific basis and data reference for practical engineering applications. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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High-Throughput Calculation for Meso-Contact of Asphalt Mixture Skeleton TANG Cheng, WANG Duanyi, YUN Di, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (4): 135-144.   DOI: 10.12141/j.issn.1000-565X.220514 Abstract （1688）   HTML （80）    PDF（pc） （2884KB）（481）       Knowledge map    Save In order to realize the high-throughput calculation of meso-contact for asphalt mixture skeleton, this paper firstly put forward two contact calculation methods, the neighbor list method and the improved window search method, and then four asphalt mixtures AC13, AC16, OGFC13 and SMA13 were used to compare the difference in calculation accuracy and efficiency among two new methods and exhaustive method, window search method and iPas software, and the range of image resolution that can achieve the balance of calculation speed and accuracy was investigated using virtual specimens. Finally, the applicability of the high throughput calculation method was verified. The results show that neighbor list method can avoid the redundant contact calculation of contact aggregate pairs with the exhaustive method, and the improved window search method can accomplish the purpose of a one loop sweep of the traditional window search method by morphological expansion processing. Neighbor list method, exhaustive method, window search method, improved window search method and iPas software have the same accuracy although there are differences in calculation principles. The order of computational efficiency of different calculation methods is: neighbor list method > exhaustive method > Improved window search method >iPas software > window search method. The decrease of image resolution will improve the speed of contact calculation but reduce the accuracy of contact point calculation results. Considering the requirements of both accuracy and efficiency, a balance of calculation speed and accuracy can be realized when the image resolution range is 0.05~0.075 mm/pixel. The neighbor list method can effectively realize the high throughput characterization of meso-contact of asphalt mixture skeleton. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Reconfigurable GNSS RF Receiver for High-Precision Positioning and Orientation LI Bin, WANG Riyan, CHEN Zhijian, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (8): 89-97.   DOI: 10.12141/j.issn.1000-565X.220177 Abstract （779）   HTML （30）    PDF（pc） （3689KB）（451）       Knowledge map    Save Aiming at the problem of multiple types of requirements and large volume, this paper introduced a highly integrated and reconfigurable Global Navigation Satellite System (GNSS) Radio Frequency (RF) receiver for high-precision positioning and orientation of satellite navigation. By adopting four reconfigurable reception channels and receiving full frequency band GNSS signals in parallel, it achieved a single chip supporting high-precision positioning or orientation applications, significantly reducing the volume and cost of navigation terminals. To improve broadband signal reception, the paper proposed a new type of inductorless high linear low noise transconductance amplifier (LNTA). It can eliminate the use of source and load inductors, reduce gain and noise fluctuations when operating in navigation signals at different frequency points, and it is conducive to the reconfiguration of multimode and multi frequency reception and reduces the power consumption of LNTA. A novel IQ phase compensation method was proposed to address the issue of IQ phase imbalance. A programmable switch array with variable impedance was directly designed on the clock controlled latch path of the binary frequency division circuit. By changing the delay time of the 25% duty cycle orthogonal LO, the corresponding branch output LO phase adjustment was realized, achieving calibration of IQ imbalance and improving the image rejection rate (IRR). Testing data shows that the RF receiver achieves full band signal coverage of GNSS from 1.15 to 1.65 GHz, a minimum noise figure of 2.7 dB, and an output third-order intermodulation point power of 34.7 dBm. Adopting a low intermediate frequency and zero intermediate frequency reconfigurable architecture, it can flexibly receive multimode GNSS signals with a bandwidth of 0.8~80 MHz. By compensating for IQ imbalance and improving channel layout, 58.1 dB IRR and 57 dB channel isolation can be achieved, effectively reducing the impact of image interference and inter channel interference. Under a 1.2 V power supply, the power consumption of the receiving channel is only 24.7 mW, which can meet the high integration and diversified application requirements of high-precision positioning and orientation GNSS RF receivers. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Review of Research on Road Traffic Detectors and Its Optimized Deployment Methods XU Zhihang, YAO Xinpeng, XU Zhigang, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (10): 68-88.   DOI: 10.12141/j.issn.1000-565X.230223 Abstract （1839）   HTML （15）    PDF（pc） （3824KB）（429）       Knowledge map    Save A widely studied and concerned problem in the traffic network research is how to optimize the location and number of road traffic detectors, so as to obtain real-time and accurate diversified traffic situation information and provide a comprehensive information basis for traffic control departments and as a basis for reasonable decision-making. The key to this problem is to select a suitable detector type and build a decision model according to the research purpose. At the same time, considering the constraints such as the investment cost limit and the number of road sections, appropriate heuristic algorithm should be used to solve the model to get the best number and location of detectors. This paper summarized the optimal layout of road traffic detectors from the types of road traffic detectors, application scenarios, data acquisition indexes and research objectives of various optimization layout studies. Firstly, the detector was divided into two categories according to the installation mode: stationary traffic detector and mobile detector, and the principle, characteristics, advantages and disadvantages of each type of detector were described in detail. Secondly, the application of various types of road traffic detectors in different scenarios and the corresponding data acquisition indicators are given. Then, according to the research purpose of optimization layout methods in the research literature, the optimization layout problems of road traffic detectors were divided into three types: user-oriented travel time estimation, traffic flow observation/estimation, and traffic event detection. And this paper discussed the development course, development direction, problem research model constructed, problem solving methods, and existing shortcomings of these studies. Finally, it summarized a large number of existing studies. And it pointed out that in the complex situation of large traffic network scale, prominent traffic uncertainty and rapid development of wisdom, future research should take the diversity of traffic information detection as the leading factor, fully consider the combination arrangement of different types of traffic detectors, various uncertainties in the traffic network and various scenarios, etc., so as to build a complete optimization model to solve the optimization arrangement of road traffic detectors. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research Progress on Key Technologies in the Cooperative Vehicle Infrastructure System LIN Hongyi, LIU Yang, LI Shen, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (10): 46-67.   DOI: 10.12141/j.issn.1000-565X.230200 Abstract （4922）   HTML （30）    PDF（pc） （1996KB）（416）       Knowledge map    Save With the steady growth of urban car ownership, the issue of traffic congestion is becoming increasingly prominent, bringing great pressure to urban development. To respond effectively to this challenge, it is critical to develop methods that can improve transport efficiency and reduce energy consumption. In current context, the Cooperative Vehicle Infrastructure System (CVIS), an ideal solution for realizing green and intelligent transportation systems, has become an important direction in both transportation research and practice. By integrating and optimizing various traffic resources, CVIS not only enhances traffic efficiency and reduces energy consumption but also provides key technical support for achieving “dual carbon” goals. This paper thoroughly analyzed the fundamental concepts, research methodologies and application scenarios of CVIS, and delved into its four core technological modules: fusion perception, driving cognition, autonomous decision-making, and cooperative control. The paper reviewed and summarized research achievements within these modules, ranging from traditional methods to the latest in deep reinforcement learning techniques. It also explored the potential applications of these technologies and methods for enhancing traffic efficiency, reducing energy consumption, and improving road safety. Finally, the paper scrutinized numerous challenges that CVIS may encounter in practical applications, including the security of information transmission, system stability, and environmental complexity. To overcome these challenges, the paper looked forward to the future development in four areas: developing datasets that integrate vehicle-side and roadside information, enhancing the fusion accuracy of multi-source perception information, improving the real-time performance and safety of CVIS, and optimizing multi-vehicle cooperative decision-making control methods under complex conditions. As a result, this paper not only has important reference value for the advancement of CVIS technology, but also provides important guidance for the future planning and construction of urban transportation systems. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Flexible Bus Scheduling Optimization for Integrated Hub Connections in the Context of MaaS YANG Min, CHEN Shantao, JIANG Ruiyu, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (10): 22-30.   DOI: 10.12141/j.issn.1000-565X.230224 Abstract （1694）   HTML （13）    PDF（pc） （2361KB）（378）       Knowledge map    Save As a crucial complement to conventional public transportation, flexible bus can provide demand-responsive services tailored to specific groups, and it has been successfully implemented and proven effective in foreign countries. However, whether it can be applied to connect passengers at comprehensive transport hubs and alleviate the increasing pressure of passenger flows at these hubs, which has become a prominent issue in the field of urban public transportation in China, warrants further investigation.To address this, this research established a flexible bus dispatching optimization method for comprehensive hub connection. Based on the characteristics of data sharing and flexible response of MaaS system, a MaaS-based flexible connecting bus dispatching service process was constructed. Considering both passengers’ punctuality requirements and the cost considerations of public transit operators, the study developed a multi-objective optimization model by incorporating constraints like time windows, vehicle capacity, and station services. The multiple objective model was transformed into a single objective model by unifying the solution direction, normalization and empowerment. The differential evolution algorithm was designed based on the ideas of encoding, decoding and maximum heap, and the model was verified by taking the railway hub area of Nanjing South Railway Station as a case. Relying on smart card data from selected bus routes in the vicinity of Nanjing South Station in May 2021, the study analyzed the spatial distribution characteristics of passenger travel demands at the hub and established predefined demand sites and passenger travel needs. The model algorithm was iteratively optimized, resulting in a fitness value of 0.921 2 and an average passenger satisfaction of 89.77%. The algorithm converges within 50 iterations, thus verifying the feasibility and effectiveness of the model and algorithm. Sensitivity analysis demonstrates that the model and algorithm remain highly applicable even when passenger demand scales change. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Coupling Analysis of Rail Transit Stations’ Network Centrality, Ridership and Spatial Heat Map WU Jiaorong, CHEN Caiting, DENG Yongqi Journal of South China University of Technology(Natural Science Edition)    2024, 52 (5): 31-42.   DOI: 10.12141/j.issn.1000-565X.230302 Abstract （197）   HTML （13）    PDF（pc） （6507KB）（354）       Knowledge map    Save Urban spatial heat map reflects population aggregation and street vitality. In order to explore the interactive relationship between urban rail transit and spatial heat map, this study used Baidu heat map and rail transit station ridership data to analyze the coupling characteristics between network centrality, ridership and nearby spatial heat index of rail transit stations on a micro level, taking Shanghai as a case study. Firstly, it investigated the overall coupling relationship between two categories of station attributes and spatial heat through Pearson bivariate correlation analysis. Then, bivariate spatial autocorrelation and geographically weighted regression analysis methods were introduced to explore the spatial association patterns between network centrality and spatial heat, as well as between spatial heat and ridership, followed by a spatial differentiation comparison between the two coupling types. The results show that the coupling relationship between rail network centrality and spatial heat is obviously better than that between ridership and spatial heat at station level, since traffic location advantage can usually develop higher spatial heat, while ridership may be affected by more complex factors. Spatial heat map is more suitable for quantifying the interaction between rail transit and urban space in areas outside the urban core, where increasing rail network centrality has a multiplier effect on spatial heat improvement, but improving spatial heat in areas with low-density development is more conducive to stimulating ridership. It is feasible to evaluate the ridership potential of new stations outside the urban core area by using spatial heat map, but this data alone is not enough to predict ridership. The urban renewal around rail transit stations can be optimized by referring to the differences between the two types of coupling at different spatial locations. This study explored the analytical framework for improving the layout of rail transit network based on urban spatial heat map, and optimizing TOD (Transit-Oriented Development) stations for factors negatively affecting their coupling. It provides a new perspective for measuring the man-land relationship of urban rail transit on the micro level. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Driverless Obstacle Avoidance and Tracking Control Based on Improved DDPG LI Xinkai, HU Xiaocheng, MA Ping, et al. Journal of South China University of Technology(Natural Science Edition)    2023, 51 (11): 44-55.   DOI: 10.12141/j.issn.1000-565X.220747 Abstract （1580）   HTML （17）    PDF（pc） （4763KB）（340）       Knowledge map    Save In the process of tracking and obstacle avoidance control of driverless vehicles, the controlled object has nonlinear characteristics and variable control parameters. The linear model and the fixed mathematical model of driverless vehicles are difficult to ensure the safety and stability of the vehicle in complex environments, and the driverless discrete control process increases the difficulty of control. To address such problems, in order to improve the accuracy of real-time control tracking trajectory of driverless vehicles, and at the same time reduce the difficulty of the whole control process, the paper proposed a Monte Carlo-depth deterministic policy gradient-based obstacle avoidance tracking control algorithm for driverless vehicles. The algorithm builds a control system model based on a deep reinforcement learning network, and adopts excellent training samples in the strategy learning sampling process. It optimizes the network training gradient with the Monte Carlo method, and makes a distinction between good and bad training samples for the algorithm. The excellent samples are used to find the optimal network parameters through a gradient algorithm, so as to enhance the learning ability of the network algorithm and realize a better and continuous control of the driverless vehicle. Simulation experiments of the control method were carried out in the computer simulation environment TORCS. The results show that the proposed improved DDPG algorithm can be applied to effectively achieve the obstacle avoidance tracking control of the driverless vehicle, and the tracking accuracy and obstacle avoidance effect of the unmanned car under its control is better than that of the deep Q network algorithm and the DDPG algorithm. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Experimental Study on Heat Transfer Performance of Separated Heat Pipe Heat Exchanger in Communication Base Station GAN Yunhua, LIAO Yuepeng, YUAN Hui, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (6): 109-118.   DOI: 10.12141/j.issn.1000-565X.220499 Abstract （371）   HTML （3）    PDF（pc） （3401KB）（333）       Knowledge map    Save Communication base stations are facing the problems of uneven heat dissipation and high energy consumption of the heat dissipation systems. The separated heat pipe heat exchanger can replace air-conditioning in communication base stations and effectively reduce the energy consumption of base station heat dissipation systems. The heat transfer performance of separated heat pipe heat exchanger is affected by factors such as filling ratio, working fluid type and air volume. In order to study the influence of different factors on heat transfer performance, the difference between theoretical filling ratio and the actual filling ratio was analyzed through theoretical calculation. The experimental platform was built to study the heat transfer performance of heat exchanger under different filling ratios, the difference of heat exchanger performance under different high and medium temperature working fluids, and the influence of indoor and outdoor fan power change on heat exchanger performance. The study finds that when the working fluid R134a is used, the error between the theoretical value and the actual value of the minimum filling ratio is 4.74%, the optimal filling ratio range of the heat exchanger is 27.1%~47.9%, the optimal filling ratio is 31.6%, and the equivalent heat transfer coefficient of the heat exchanger under the optimal filling ratio is 909 W/℃. With the increase of filling ratio, the phase change area inside the heat exchanger increases first and then decreases, and the heat transfer form changes from sensible heat transfer of vapor working fluid to latent heat transfer of the phase change of the working fluid, and then to sensible heat transfer of the liquid working fluid. The high temperature working fluid is not suitable for the separated heat pipe heat exchanger. When using the high temperature working fluid, there is no obvious phase change area inside the heat exchanger. The lower the boiling point of the working fluid is used, the larger the phase change area, the better the performance of heat exchanger, and the larger the range of its optimal filling ratio. With the increase of power of indoor and outdoor fans, the performance of the heat exchanger increases rapidly and then slows down. However, due to the poor heat dissipation conditions on evaporator side, the improvement of the heat transfer performance of the system by increasing the power of internal fan is more significant than that of the external fan. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Cognitive Diagnosis Model Integrating Forgetting and Importance of Knowledge Points LIU Yupeng, ZHANG Lei Journal of South China University of Technology(Natural Science Edition)    2023, 51 (5): 54-62.   DOI: 10.12141/j.issn.1000-565X.220279 Abstract （219）   HTML （13）    PDF（pc） （1829KB）（330）       Knowledge map    Save Intelligence education is the key research direction of artificial intelligence. The most important is to describe the students’ cognitive process by ultilizing the knowledge points in the test questions. Aiming at the problem that the cognitive diagnosis model is insufficient for mining students, test questions and their interactive information, this study proposed a cognitive diagnosis model integrating forgetting and the importance of knowledge points. According to the historical interaction between the test questions and knowledge points, the model introduces forgetting factors in combination with the difficulty information of knowledge points, thus alleviates the problem of insufficient information mining for students. Through the attention mechanism, the importance information of the test questions to the knowledge points was obtained to alleviate the problem of insufficient information mining of the test questions. Learning the interaction relation between students and test questions through Transformer alleviates the problem of insufficient interaction information between students and test questions. The results of experiments carried out on the classic dataset show that the accuracy Acc, root mean square error (RMSE), and the area under curve (AUC) values of this method on the Math1, Math2, and Assistment datasets are 0.716, 0.445, 0.776, 0.725, 0.432, 0.807, 0.741, 0.427, 0.779, respectively. Compared with other existing models, the proposed method has better results. The proposed method illustrates the importance of knowledge importance and timeliness for cognitive modeling. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Conflict-Free Path Planning For Multi-AGVs in Automated Terminals Considering Road Load Balancing WEN Huiying, YUAN Yuqing, LIN Yifeng Journal of South China University of Technology(Natural Science Edition)    2023, 51 (10): 1-10.   DOI: 10.12141/j.issn.1000-565X.230227 Abstract （1806）   HTML （22）    PDF（pc） （3304KB）（326）       Knowledge map    Save With the increasing demand for container transportation and the widespread application of new information technologies, the automation of container terminal operations has become the main development trend in domestic and international ports. It can not only effectively improve the efficiency and safety of terminal operations, but also significantly reduce the demand for human resources and the operational costs. The horizontal transportation system is an essential part of the container terminal handling system and an important link enabling the highly efficient container transportation between the quayside and the storage yard, so its operational reliability and the reasonableness of the scheduling directly affect the operational efficiency of the automated container handling system. The mostly used horizontal transportation equipment in container terminals is the automated guided vehicles (AGVs), which is responsible for horizontal transportation from the front quay crane to the rear yard in automated container terminals. In actual operation process, conflicts and congestion is inevitable when multiple AGVs operate simultaneously. On this basis, this paper used conflict-based search (CBS) to solve the conflict problem arising from the cooperative operation of multi-AGVs at the terminal. The upper layer algorithm searched for conflicts among AGVs, while the lower layer algorithm used the A* algorithm for path planning of AGVs. A load factor was introduced into the heuristic function of the A* algorithm in order to avoid congestion in the path planning and achieve load balancing on terminal roads. Further, a sliding time window conflict resolution (STWCR) based on CBS was adopted to improve computational efficiency for multiple AGVs path planning in the continuous operation scenario of multiple task points at the terminal. Simulation experiments verified that the proposed algorithm in this paper can effectively solve the conflict problem of multiple AGVs path planning at the terminal, while balancing the road network load, alleviating local road congestion, and improving the utilization of road resources. The research results of this paper provide a reference for the optimization of the horizontal transportation system in automated container terminals. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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AdfNet: An Adaptive Deep Forgery Detection Network Based on Diverse Features LI Jiachun, LI Bowen, LIN Weiwei Journal of South China University of Technology(Natural Science Edition)    2023, 51 (9): 82-89.   DOI: 10.12141/j.issn.1000-565X.220825 Abstract （231）   HTML （11）    PDF（pc） （1909KB）（314）       Knowledge map    Save The harm caused by video tampering has been endangering people’s lives, which makes deep forgery detection technology gradually obtain widespread attention and development. However, current detection methods could not effectively capture noisy residuals due to the use of inflexible constraints. In addition, they ignore the correlation between texture and semantic features and the impact of temporal features on detection performance improvement. To solve these problems, this paper proposed an adaptive network (AdfNet) with diverse features for deep forgery detection. It helps the classifier to judge authenticity by extracting semantic features, texture features and temporal features. The paper explored the adaptive texture noise extraction (ATNEM) mechanism, and flexibly captured the noise residuals in non-fixed frequency bands through unpooled feature mapping and frequency-based channel attention mechanism. The deep semantic analysis guidance strategy (DSAGS) was designed to highlight the tampering traces through spatial attention mechanism, and guide the feature extractor to focus on the deep features of the focus region. The paper studied multi-scale temporal feature processing (MTFPM), and used temporal attention mechanism to assign weights to different video frames and capture the difference of time series in tampered videos. The experimental results show that the ACC score of the proposed network in the HQ mode of FaceForensics++(FF++) dataset is 97.41%, which is significantly better than that of the existing mainstream algorithms. Moreover, while maintaining the AUC value of 99.80% on the FF++ dataset, the AUC value can reach 76.41% on Celeb-DF, reflecting strong generalization. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Electric Bus Scheduling Method Considering Differences in the State of Health of Batteries BIE Yiming, ZHU Aoze, CONG Yuan Journal of South China University of Technology(Natural Science Edition)    2023, 51 (10): 11-21.   DOI: 10.12141/j.issn.1000-565X.230279 Abstract （1927）   HTML （18）    PDF（pc） （1868KB）（309）       Knowledge map    Save Electric buses (EBs) have the advantages of zero-emission and low energy consumption in operation. The electrification of urban buses is being vigorously promoted in many countries to reduce carbon emissions and promote the realization of the “Carbon peaking and Carbon neutrality” goals. However, due to financial constraints and the fact that fuel buses have not yet reached the end of life and bus companies usually replace fuel buses with EBs in batches, there are differences in the battery health degree and driving range of each bus on the line, which makes the optimization of the vehicle scheduling scheme more complicated. Considering the impact of battery differences in the state of health and time-of-use tariff, this paper proposed an optimized scheduling model for single-route, with the objective of minimizing average daily charging costs, EB acquisition costs, and battery loss costs. Then, the model was transformed into two sub-problems, the vehicle scheduling problem and the charging scheduling problem. In the outer layer, the vehicle scheduling problem was solved by the improved simulated annealing algorithm (ISAA), whose perturbation strategy is designed with the operating intensity differences among EBs. And Gurobi was employed to solve the charging scheduling problem in the inner layer. Finally, an actual EB route was taken as an example to verify the effectiveness of the method, and the method was compared with the simulated annealing algorithm in the perturbation strategy which does not consider differences in vehicle operating intensity. Results show that the ISAA can increase the convergence speed by 31.8% and achieve high-quality solutions in a short time. Moreover, the generated scheduling scheme can not only arrange EBs to be charged preferentially in the off-peak period of electricity prices but also reduce the EB fleet size. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Analysis of Crossing Behavior of Non-Motor Vehicle at Overlap Phase Signal Intersections WEN Huiying, LIU Hao, DU Yingxin, et al Journal of South China University of Technology(Natural Science Edition)    2023, 51 (8): 1-11.   DOI: 10.12141/j.issn.1000-565X.220779 Abstract （320）   HTML （20）    PDF（pc） （2549KB）（307）       Knowledge map    Save In order to improve the safety level of non-motor vehicle traffic at signalized intersections, based on the survey data of signalized intersections with overlapping phase control in Guangzhou, this study analyzed the influencing factors of non-motor vehicle crossing behavior based on the C5.0 decision tree algorithm. Considering the influence of different periods on the crossing behavior of non-motor vehicles in the signal cycle, the study divided a complete signal cycle into four risk periods according to the risk conflict of non-motorized vehicles crossing the street, namely, the opposite green light risk period, the same direction green light safety period, the same direction green light risk period and the vertical direction risk period. And it divided the crossing behavior into three categories according to the waiting selection of non-motor vehicles at the intersection and whether or not to run red-light, namely, risky, opportunistic and law-abiding. It studied the influencing factors of the three types of crossing behavior by constructing a C5.0 decision tree model and analyzed and evaluated the classification effect of the model. The results show that the overall accuracy of the model classification results is greater than 83.04%, the AUC is greater than 0.880, and the model prediction accuracy is good. The crossing behavior of non-motorized vehicles at signalized intersections with overlapping phase control is mainly significantly related to the traffic environment, while the factors related to the rider’s behavior are less significant. The arrival risk period, non-motor vehicle signal light facilities, conflicting motor traffic flow, number of lanes and crossing risk have significant impacts on the occurrence of risk-taking crossing behavior, among which the arrival risk period is the most important influencing factor. The number of lanes, red-light time and arrival risk period have significant impacts on the occurrence of opportunistic crossing behavior, among which the number of lanes is the most important influencing factor. The conflicting motor traffic flow flow, signal period, number of lanes, crossing area and crossing risk have significant impacts on the occurrence of law-obeying crossing behavior, among which the conflicting motor traffic flow is the most important influencing factor. Table and Figures | Reference | Related Articles | Metrics | Comments（0）