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With the rapid development of China’s logistics and transportation industry, how to reasonably and efficiently use drones to carry out logistics and distribution business under the background of UAM has become a focus of attention for social enterprises. It is urgent to propose a feasible logistics drone take-off and landing sites layout planning method based on reality. The article first explains the principles and connotations of the layout of logistics unmanned aerial vehicle take-off and landing sites, dividing logistics distribution scenarios into three sub scenarios: urban end of pipe distribution, medical material distribution, and short distance logistics transportation. Then, based on strong constraint conditions, preliminary site selection is carried out for each sub scenario. The HRW-Kmedoids algorithm is used to optimize the site selection points for each sub scenario, and the final site selection and alternative points are obtained. The Huangpu District of Guangzhou is
Zhang, ShuweiChen, ZhilongWang, Weiqing
The gearbox is a key component of the mechanical transmission system, and its fault diagnosis is essential to the reliability of the equipment. However, obtaining fault samples under actual working conditions for gearbox fault diagnosis is challenging. In this paper, the rigid-flexible coupling dynamic simulation model of the gearbox is established, and the co-simulation of gear normal, crack, and breakage is carried out in the ADAMS and MATLAB environments. The comparison between the simulated and measured signals shows that the simulation method can accurately reflect the key characteristics, such as rotation frequency and meshing frequency, and verify its reliability and accuracy. The research results can provide effective data support for gearbox fault diagnosis and improve the operational safety of mechanical systems.
Li, DongxiaoZhang, QianqiZhang, ZhongzhengLi, Yongbo
This study addresses the insufficient tractive trafficability of four-track unmanned amphibious tracked vehicles (UATV) in beach terrain by proposing an optimization strategy based on coordinated suspension height and hitch point adjustment. A mathematical model of vehicle drawbar pull was established to systematically analyze the influence mechanisms of vertical load distribution, suspension adjustment, and hitch point elevation on tractive trafficability. DEM-MBD coupling simulations revealed differentiated traction laws under sandy loam and clay conditions, particularly regarding track overlap effects. Results demonstrate that in sandy loam, rear-axle traversal over front-axle tracks reduces drawbar pull due to soil loosening, whereas track overlap enhances drawbar pull in clay through soil compaction. Nine suspension-hitch configurations were tested, validating optimization strategies: increased front-axle loading (Configuration a) in sandy loam and reduced front-axle loading
Chen, YaoyaoGao, XueWang, WenhaoXu, Xiaojun
The features of airport clusters have a big impact on regional air transport. But problems within these clusters also affect airline operations. This study uses the Data Envelopment Analysis (DEA) model. It selects 16 airlines of different sizes as samples. It also identifies relevant input and output indicators to measure operational efficiency. The results show that the efficiency of large and medium-sized airlines generally went up. Small airlines have shown a slow but steady improvement in efficiency, with significant volatility due to cost and slot constraints. So, the study analyzes pure technical efficiency, scale efficiency, and comprehensive efficiency. It finds out the changing patterns of operational efficiency among airlines of different sizes and the reasons behind them.
Hu, KexinHuang, Tao
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Bi, TengfeiNie, JiachengDu, ChangjiangJi, YuechenWang, SongSun, Jiawei
According to the working characteristics of the tire changer, the movement characteristics of its rim clamping mechanism are analyzed, and the complex movement structure is abstracted and simplified into four identical six-bar mechanism subunits. One of the subunits is taken as the research object, and the mathematical model of kinematic analysis is established. Using MATLAB software to simulate and analyze the motion law of each component, the mechanical characteristics of the component are analyzed. The optimization of the design parameters of the “six-bar mechanism subunit” is realized, the rim clamping mechanism becomes more stable, and the clamping force follows the diameter of the rim more closely.
Zhao, FengqinZhou, LiyaoWang, MantongHuo, Fengwei
Unmanned Aerial Vehicles (UAVs) are now indispensable in low altitude urban logistics for their efficiency and versatility. In order to boost their practical performance in such a mission, in this paper, we study three typical UAV dispatching problems: (1) single UAV routing with battery constraints, (2) multi UAV task allocation and routing balance and (3) multi UAV minimization of UAVs with hard time window constrains. The mathematical models of each case are constructed, and the optimization algorithm such as greedy algorithm, cluster algorithm, genetic algorithm and simulated annealing algorithm are designed for each case. The simulation shows that greedy algorithm has better optimization in resource utilization and the convergence of the simulated annealing algorithm is better under the complex constraints. This results provide an algorithmic insight for the improved UAV scheduling problem in MUCLL environment.
Wang, JiamingGuo, JingDu, NingWei, Mengju
The reliability of aviation maintenance personnel directly impacts flight safety, yet systematic methodologies for the quantitative prediction of human error probability (HEP) in this domain remain lacking. To address this gap, a novel human factors reliability analysis method for aviation maintenance is proposed, extending the SPAR-H model through Evidential Reasoning (ER). This method is implemented as follows: Maintenance tasks are decomposed into subtasks. Subsequently, the eight types of Performance Shaping Factors (PSFs) for each subtask are evaluated by domain experts according to defined PSF levels. Expert judgments are then aggregated using Evidential Reasoning theory, enabling the calculation of aggregated PSF levels. These aggregated levels are interpolated to determine the corresponding impact multipliers. Finally, the HEP for aviation maintenance operations is calculated by integrating the SPAR-H basic error probability model with task series/parallel logic rules. The
Meng, MengMa, NingGuan, ZhongqingHan, ZuyangNan, WenxueCai, Hongbin
With the development of manned spaceflight and deep space exploration, TC4 alloy has been used for the structure design of aircraft due to its excellent characteristics. Thermal radiation properties (solar absorptance and hemispheric emittance) of TC4 alloy are becoming important design indices. We investigated TC4 alloys with different surface morphologies and the effect of micro-morphology on thermal radiation properties. The results show that the solar absorptance of the alloys is sensitive to surface roughness and microstructure. As the surface roughness or crack increases, solar absorptance increases. Hemispheric emittance of the alloys increases as surface roughness is added, but it is insensitive to the micro-nanostructure of the alloys.
Liu, YangZhu, XiaoxiRen, ChaolongLi, DasongWan, LeiHuang, Feiyu
The compensation rope is a special steel wire rope used as a driving component in the ratchet device. The compensation rope will endure severe random cycling loading during service time, which will lead to fatigue failures and catastrophic disasters. Experimental studies are hard to mimic the practical working conditions and time consuming, therefore, this study establishes a finite element model of the compensation rope and simulates the stress distribution under axial tensile and bending loads. Fatigue life is analysed based on both stress and strain fatigue theories under alternating tensile and bending loads. The results indicate that under axial tensile loads, the stress in the outermost wires of the core strands of the compensation rope is the largest, with the minimum fatigue life. As the stress ratio of the alternating tensile load increases, the fatigue life also improves due to smaller stress amplitudes. Under the conditions of bending loads, the outermost wires of the
Du, FeiCong, JiajiaBian, HaoxiangZhu, JunchenZhao, Aiguo
In order to reduce traffic accidents caused by cars straying from lanes, a lane line recognition and deviation warning system based on machine vision is designed. It mainly includes image preprocessing, lane line detection, and the design of a deviation warning model. “In this study, an ROS-based intelligent vehicle-mounted camera is adopted for road image collection. To reduce the computational load of data processing while guaranteeing the algorithm’s accuracy and reliability, grayscale conversion and region of interest (ROI) extraction are implemented to finish the image preprocessing stage. Additionally, a fusion strategy of global and local thresholds is introduced to enhance both the operational speed and detection accuracy of the algorithm” use the Canny operator for the edge feature extraction; and complete the fitted lane lines with the improved Hough transform. Finally, based on the Kalman filter and camera viewpoint conversion coefficient algorithm, the lane line offset is
Wang, XufengZhang, ChunshuWang, YanChen, YihuiJi, Rui
Nowadays, the majority of intelligent fault diagnosis approaches are still centered on individual faulty components, while only a limited number of models are capable of performing integrated diagnosis for rotating systems that consist of shafts, bearings, and gears. Under variable-speed operating conditions, the large scale of vibration data further complicates the process of effective feature extraction. To improve these challenges, this study develops a comprehensive diagnostic framework for rotating components, termed WGAN-SAFC. The proposed architecture integrates a Wasserstein Generative Adversarial Network (WGAN) with a hybrid structure of stacked autoencoders and sparse filtering (SAFC). SAFC integrates the feature-learning capability of SAE and the sparsity-driven representation of SF, while incorporating adversarial data generation to address sample imbalance and enhance fault diagnosis performance. Experimental verification on collected vibration datasets demonstrates that
Li, ShunmingFeng, Mengqi
As a key component of unmanned aerial vehicles (UAVs), the stable operation of motor bearings is of vital importance to the stability of UAVs. In view of the incomplete data set in the actual diagnosis process, samples not encountered during model training are highly likely to appear. This paper proposes an Adaptive Class-Incremental Learning(ACIL) intelligent fault diagnosis method. This method construct a ResNet framework embedded with Coordinate Attention as the base architecture for class-incremental learning. Furthermore, the Information Preservation Example Selection(IPES) method is utilized to alleviate catastrophic forgetting and update the model from the previous phase using knowledge distillation under coordinate attention. The effectiveness of this method is verified through experiments on the bearing test dataset. The results show that, both average incremental accuracy and average incremental forgetting rate achieve state-of-the-art performance, which means that the
Song, ZiyangLu, JiantaoWu, WeiLi, Shunming
Thermal shock, space combined irradiation test, and humidity test were carried out on one type of multilayer insulation. We summarized and analyzed the change in solar absorptance and hemispheric emittance before and after the environmental test. At the same time, the thermal stability and vacuum pollution characteristics were investigated by thermal weightlessness test and thermal vacuum outgassing test. The results show that the change in thermal radiation performance before and after the environmental test is no more than 0.02, the heat resistance is 350 °C, TML is 0.50%, and CVCM is 0.05% at 135 °C. It is observed that the thermal radiation performance of the material is hardly degraded by thermal shock, and humidity and space combined irradiation. The multi-layer insulation shows good thermal radiation characteristics, thermal stability, and low space pollution characteristics.
Li, WeiyuLiu, YangLi, XiujieSun, ShuHuang, FeiyuYang, Yaodong
The comprehensive deployment of smart garbage bins realizes the real-time monitoring of garbage generation and recycling demand, and the use of intelligent network connected collection and transportation vehicles can sense dynamic data such as vehicle location and load in real time. In this context, how to efficiently integrate these dynamic information to build a responsive scheduling system has become a key requirement of smart city management. Aiming at this requirement, this paper proposes a dynamic routing optimization model of electric garbage collection and transportation vehicles considering charging constraints, and designs a hybrid PSODE combining improved particle swarm optimization(PSO) and differential evolution(DE) to solve the model. By introducing a nonlinear decreasing strategy of inertia factor and a dynamic learning factor adjustment mechanism, an adaptive optimization framework of algorithm parameters is established to enhance the adaptability of the algorithm
Shen, XiaolongMa, Huimin
The two-way ten-lane expressway has the significant characteristics of “large traffic volume, mixed vehicle types, and heavy loads”, which makes the impact of traffic flow status on accident risk present nonlinear characteristics. Traffic flow fluctuations not only directly affect the probability of accidents, but also amplify the spatiotemporal differences in rescue needs through mechanisms such as lane occupancy time and accident chain reactions. Therefore, the essence of resource allocation on a two-way ten-lane expressway is the “spatiotemporal matching problem between dynamic risks and limited resources”, which requires both quantifying the spatiotemporal evolution of risks and coping with the high uncertainty of the traffic system. Aiming at the problem of inefficiency of traditional empirical resource allocation under complex traffic conditions, this study proposes a dynamic optimization framework based on multidimensional risk assessment for emergency rescue resource allocation
Kan, YoujunCao, YangShi, XiaominGao, Shangjie
To address the limitations of the traditional A* algorithm in lane-level navigation, we propose an autonomous vehicle path planning algorithm based on high-precision maps and an improved A* algorithm to ensure effective application in complex traffic environments. We construct a hierarchical high-precision map based on the Lanelet2 framework to achieve structured modeling of complex road environments. To address the adaptability issues of the A* algorithm in lane-level navigation, we propose optimization schemes, including heuristic function improvements, path segment division, and target point validity verification, to ensure that vehicles can autonomously change lanes on multi-lane roads. By combining dynamic programming (DP) and quadratic programming (QP), we ensure the safety and smoothness of the path. Simulation results demonstrate that the optimized algorithm enables smooth stopping and starting at traffic lights in structured road environments and autonomous lane changes on
Wang, SiyuZhou, RongShi, TianXu, ZhenZhao, Zhiguo
Public transportation serves as a crucial component of urban mobility, contributing to the alleviation of urban congestion, reduction of travel expenses, and mitigation of air pollution. Nonetheless, the dynamic passenger demand and the complex traffic conditions render traditional bus timetables inadequate, leading to ineffective allocation of public transportation resources. Consequently, it is essential to create bus timetables that are responsive to actual traffic scenarios and fluctuating passenger demand. This study regards the bus timetable planning problem as a Markov decision-making process within a discrete time framework, proposing a deep reinforcement learning-based optimization model for bus timetables. In particular, the model is designed to account for both bus companies and passengers, incorporating a state space and reward calculation method that emphasizes passenger comfort. Then Deep Q-Network (DQN) methodology is employed to issue instructions on whether a bus
Xu, JieXia, DongYang, JianxiWang, Bing
To enhance the rescue efficiency of expressway emergencies and reduce the impact on network operation, this study developed an optimization model for the strategic placement of emergency rescue stations. Firstly, a node importance assessment method is designed to measure the importance of each node in the expressway network by considering both local and global impacts; secondly, an emergency rescue station selection model is constructed based on the node importance to achieve the highest coverage satisfaction, the highest rescue efficiency and the lowest construction cost. Taking the expressway network in Shaanxi Province as an example, a particle swarm algorithm based on non-dominated sorting (NSPSO) is designed to solve the problem. The results demonstrate that, with the same number of rescue stations, the model of Site Selection of Emergency Rescue Stations considering node importance achieves shorter average rescue time and higher coverage satisfaction under comparable conditions.
Chen, JingliLin, ShanXu, HongkeCao, JiabaoYang, FeiLuo, Mi
In the aerospace industry, pins are crucial for fastening multiple connected structural parts, ensuring a flush connection that does not protrude from the assembly’s surface. These pins are installed through various methods to meet stringent mechanical and anti-loosening requirements, essential for aircraft structural integrity. Typical pin installation techniques include clearance fit with punch point installation, small interference fit with punch point installation, large interference fit with punch point installation, and interference fit without punch point installation. This study examines the connection reliability and manufacturability of different pin assembly processes, focusing on load testing under operational conditions. Results indicate that a small interference fit (0-0.01mm) combined with punch point installation provides high connection reliability and ease of manufacture, with punch point methods notably enhancing loadbearing capability and assembly integrity. In
Hua, Shengyan
To meet the requirements for efficient evacuation during tunnel navigation, the pontoon of the tunnel bank wall evacuation channel in a large-scale navigation building is taken as the research object. The water body and water wave are simulated using the coupled Euler-Lagrangian method and the push-plate wave method, respectively. The water boundary is processed using the viscoelastic artificial boundary method, and a simulation analysis model of the pontoon under the combined action of water waves and load is established. The results show that the average relative vertical displacement of the pontoon is basically the same under the condition of water wave and no water waves, but the fluctuation range of the pontoon is larger under the condition of water waves. When there are water waves and different loads, the maximum Mises stress distribution of the pontoon is essentially the same, and both are less than 80 MPa, meeting the strength requirements and demonstrating the rationality of
Tang, WeibiQin, PanLi, RanTao, RanHu, Zhifang
In response to the problem of manual transmission rattle noise in the acceleration process of a truck, the mechanism of the problem is analysed, and the scheme is developed and verified from two aspects: reducing the torsional vibration of the system and reducing the response of the transmission gear. The results show that, on the one hand, reducing the clutch stiffness and optimizing the torsional vibration of the system can reduce the rattle noise of the transmission; On the other hand, it can also reduce the rattle noise of transmission gears by improving the engagement precision of transmission gears and reducing the gear clearance. Considering the improvement effect, cost, and influence on other performance of the two schemes, the appropriate engineering scheme is selected to effectively solve the problem and improve the riding comfort of the product.
Yang, ZhijieXu, Binghua
Coal is an important component of China's energy structure, mainly transported by three modes: railway, waterway, and highway. In regional coal transportation, highway transport undertakes numerous collection-distribution tasks and medium-short distance transport, playing a vital and indispensable role. Considering the characteristics of the coal highway transportation market and the demand for price indices, a three-tiered coal highway freight price index system has been established, including individual indices, classified indices, and an overall index. Using order data from the logistics platform of the Coal Big Data Center, the coal highway freight price index is compiled by adopting the internationally Laspeyres chain method. The methodological selection has passed the ADF stationarity test. Economically, the coal highway freight price index is closely correlated with coal prices, with the correlation coefficient reaching over 0.7, which can reflect about the coal highway freight
Zhao, NanxiWang, XinziRong, Haoyu
In order to improve the driving safety of one-way multi-lane overtaking behavior, this paper designs and validates an overtaking warning system. By analyzing the dynamic characteristics and potential risks of the overtaking process, the prediction model of overtaking time and target lane safety gap is constructed, key parameters such as safety time distance and vehicle parameters are introduced, and three levels of danger levels and corresponding warning strategies are set. MATLAB simulation is used to verify the design of three types of typical overtaking scenarios (safe, cautious, and dangerous), and the test results show that the system can effectively differentiate the risk levels and output the warning consistent with the expectation, which verifies the reasonableness of the model and strategy
He, YuanliMu, JunjieLuo, YingZhang, WangWang, Qianwei
To investigate the disaster evolution characteristics and associated risks of heavy rainfall and flooding on urban transportation infrastructure, this study takes the extreme rainstorm event in Zhengzhou as a typical case. A multidimensional dynamic risk assessment model is employed to analyze the disaster evolution process and conduct risk evaluation. First, the three-stage evolution process and its characteristics are systematically examined. Then, based on the theory of natural disaster risk elements, a dynamic risk assessment model is constructed. The improved Order of Priority Approach (OPA) is used to determine the weights of multidimensional risk factors, and interval type-1 fuzzy logic is introduced to address the uncertainty of fuzzy indicators. Finally, the overall risk level of the heavy rainfall–flooding disaster chain is calculated and evaluated. The results indicate a high-risk level, which is consistent with the findings of the field investigation report, thereby
Zhang, YongchengWang, JianweiWu, ZiyiWang, YanLuo, QingKang, Pingping