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Establishment of a metric to characterise retroreflector properties using a consumer-grade colour camera 使用消费级彩色相机建立表征回射器特性的指标
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac039
Huayang He, Wenying Su, Qiutong Cheng
The coefficients of retroreflection and chromaticity coordinates are critical metrics for determining the quality of a retroreflector. However, conventional retroreflection measurement techniques rely heavily on the night-time colour, size, and characteristics of the sample being measured. This complicates the measurement process and leads to deviations in the test results. In addition, chromaticity cannot be determined using this approach. Therefore, it is necessary to improve the measurement accuracy, simplify the measurement process, and achieve the measurement of the traffic sign RA and chromaticity coordinates simultaneously. In this study, an improved method for retroreflector characterisation using imaging was proposed. This allowed for the measurement of the coefficients of retroreflection and the chromaticity coordinates simultaneously, and only a white standard sample was required for calibration. The primary components of the proposed system included a lighting projector, a receiver, two motorised rotational stages, a retroreflective sample holder, and customised software that used scaling factors to convert a digital signal into sample retroreflection coefficients and retroreflective chromaticity coordinates. The experimental results indicated that the raw data output from the camera exhibited a positive correlation relationship with the luminous flux from the surface of the retroreflector. The maximum measurement errors for the retroreflection and chromaticity were −12.2 cd/(lx·m2) and −2.09%, respectively. This method was inexpensive and convenient, used a commercially available digital camera, could help to identify defects in retroreflection and chromaticity for retroreflective sheeting, and led to increased accessibility for the quality control of retroreflective sheeting.
反射系数和色度坐标是决定反射镜质量的关键指标。然而,传统的反射测量技术在很大程度上依赖于被测量样品的夜间颜色、大小和特征。这会使测量过程复杂化,并导致测试结果出现偏差。此外,色度不能用这种方法确定。因此,有必要提高测量精度,简化测量过程,实现交通标志RA和色度坐标的同时测量。在这项研究中,提出了一种改进的后向反射器成像表征方法。这样可以同时测量反射系数和色度坐标,并且只需要一个白色标准样品进行校准。该系统的主要组成部分包括一个照明投影仪、一个接收器、两个电动旋转台、一个反反射样品支架,以及使用比例因子将数字信号转换为样品反反射系数和反反射色度坐标的定制软件。实验结果表明,相机输出的原始数据与反光镜表面的光通量呈正相关关系。反射率和色度的最大测量误差分别为−12.2 cd/(lx·m2)和−2.09%。该方法价格低廉,使用数码相机,可以帮助识别反光片材的反光和色度缺陷,并增加了对反光片材质量控制的可及性。
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引用次数: 0
Airborne transmission of virus-laden droplets in an aircraft cabin 载病毒飞沫在机舱内的空气传播
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac079
Li Yu, Wang Xuhui, Yang Jie, Zhang Zemiao, Wang Chenglei, Qian Bosen, Tian Xudong, Wang Tiantian
This study investigates the airborne transmission of virus-laden droplets generated by a cough of patients in an aircraft cabin to reveal the infection risk of taking an airplane. The influence of the ventilation system on flow field of the cabin was analyzed to reveal its effects on the airborne transmission of virus-laden droplets. Meanwhile, human body heat was also considered in the simulations. The results show that hot plume due to human body heat has significant impact on the upward movement of virus-laden droplets. The virus-laden droplets expelled by a cough can be transmitted to the region with two to three rows away from the generator. Particularly, the transverse motion present in the early stage of the droplet transmission results in a high infection risk to the passengers in the same row with the patient. This work gives insight into the understanding of the airborne transmission of virus-laden droplets in the entire passenger cabin.
本研究调查了飞机机舱内患者咳嗽产生的含病毒飞沫的空气传播,以揭示乘坐飞机的感染风险。分析了通风系统对客舱流场的影响,揭示了通风系统对病毒飞沫空气传播的影响。同时,模拟中也考虑了人体热量。结果表明,人体热量产生的热羽对病毒飞沫向上运动有显著影响。咳嗽排出的携带病毒的飞沫可以传播到距离发电机两到三排的地区。特别是,在飞沫传播的早期阶段出现的横向运动导致与患者同排的乘客感染风险很高。这项工作使人们对整个客舱中携带病毒的飞沫的空气传播有了深入的了解。
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引用次数: 0
Path Planning Algorithms for Self-Driving vehicle based on improved RRT-Connect 基于改进RRT-Connect的自动驾驶车辆路径规划算法
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac061
Li Jin, Huang Chaowei, Pan Minqiang
This study aims to solve path planning of intelligent vehicles in self-driving. In this study, an improved path planning method combining constraints of environment and vehicle is proposed. The algorithm designs a reasonable path cost function, then uses heuristic guided search strategy to improve the speed and quality of path planning, and finally generates smooth and continuous curvature paths based on the path post-processing method based on the requirements of path smoothness. simulation test show that compared with the basic RRT, RRT-connect and RRT* algorithms, the path length of the proposed algorithm can be reduced by 19.7%, 29.3% and 1% respectively and the maximum planned path curvature of the proposed algorithm is 0.0796 m-1 and 0.1512 m-1 respectively under the condition of a small amount of planning time. The algorithm can plan the more suitable driving path for intelligent vehicle in complex environment.
本研究旨在解决智能汽车在自动驾驶中的路径规划问题。本文提出了一种结合环境和车辆约束的改进路径规划方法。该算法设计了一个合理的路径代价函数,然后使用启发式引导搜索策略来提高路径规划的速度和质量,最后根据路径平滑度的要求,基于路径后处理方法生成平滑连续的曲率路径。仿真测试表明,与基本的RRT、RRT-connect和RRT*算法相比,在少量规划时间的情况下,该算法的路径长度分别减少了19.7%、29.3%和1%,最大规划路径曲率分别为0.0796m-1和0.1512m-1。该算法可以为智能汽车在复杂环境中规划更合适的行驶路径。
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引用次数: 1
A bearing fault diagnosis method based on a convolutional spiking neural network with spatial–temporal feature-extraction capability 基于具有时空特征提取能力的卷积尖峰神经网络的轴承故障诊断方法
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac050
Changfan Zhang, Z. Xiao, Zhenwen Sheng
Convolutional neural networks (CNNs) are widely used in the field of fault diagnosis due to their strong feature-extraction capability. However, in each timestep, CNNs only consider the current input and ignores any cyclicity in time, therefore finding difficulties in mining temporal features from the data. In this work, the third-generation neural network—spiking neural network (SNN)—is utilized in bearing fault diagnosis. SNNs incorporate temporal concepts and utilize discrete spike sequences in communication, making it more biologically explanatory. Inspired by the classic CNN LeNet-5 framework, a bearing fault diagnosis method based on a convolutional SNN is proposed. In this method, the spiking convolutional network and the spiking classifier network are constructed by using the IF and LIF model, respectively, and end-to-end training is conducted on the overall model using a surrogate gradient method. The signals are adaptively encoded into spikes in the spiking neuron layer. In addition, the network utilizes max-pooling, which is consistent with the spatial–temporal characteristics of SNNs. Combined with the spiking convolutional layers, the network fully extracts the spatial–temporal features from the bearing vibration signals. Experimental validations and comparisons are conducted on bearings. The results show that the proposed method achieves high accuracy and takes fewer time steps.
卷积神经网络以其强大的特征提取能力在故障诊断领域得到了广泛的应用。然而,在每个时间步长中,cnn只考虑当前输入,而忽略了时间上的任何周期性,因此很难从数据中挖掘时间特征。本文将第三代神经网络——脉冲神经网络(SNN)应用于轴承故障诊断。snn结合了时间概念,并在通信中利用离散尖峰序列,使其更具生物学解释性。在经典CNN LeNet-5框架的启发下,提出了一种基于卷积SNN的轴承故障诊断方法。在该方法中,分别使用IF和LIF模型构建尖峰卷积网络和尖峰分类器网络,并使用代理梯度方法对整体模型进行端到端训练。这些信号被自适应地编码成尖峰神经元层的尖峰。此外,该网络利用了最大池化,这与snn的时空特征是一致的。结合尖峰卷积层,充分提取轴承振动信号的时空特征。对轴承进行了实验验证和比较。结果表明,该方法具有较高的精度和较短的时间步长。
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引用次数: 1
Short-term traffic forecasting model – prevailing trends and guidelines 短期交通预测模型-主要趋势及指引
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac058
Kian Lun Soon, Robin Kuok Cheong Chan, J. Lim, R. Parthiban
The design parameters serve as an integral part of developing a robust short-term traffic forecasting model. These parameters include scope determination, input data preparation, output parameters, and modelling techniques. This paper takes a further leap to analyse the recent trend of design parameters through a Systematic Literature Review (SLR) based on peer-reviewed articles up to 2021. The key important findings are summarised along with the challenges to performing short-term traffic forecasting. Intuitively, this paper offers insights into the next wave of research that contributes significantly to industries.
设计参数是开发稳健的短期交通预测模型的组成部分。这些参数包括范围确定、输入数据准备、输出参数和建模技术。本文通过基于截至2021年同行评审文章的系统文献综述(SLR),进一步分析了设计参数的最新趋势。总结了关键的重要发现以及执行短期交通预测的挑战。直观地说,这篇论文为下一波对行业有重大贡献的研究提供了见解。
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引用次数: 0
Regularity and sensitivity analysis of main parameters of plate effects on the aerodynamic braking drag of a high-speed train 高速列车空气动力学制动阻力板效应主要参数的规律性及灵敏度分析
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac051
Peng Li, Shan Huang, Y. Liu, J. Niu
With increase of train speed, braking plate technology has a good application prospect in the high-speed stage of the train. Based on the 1/8th scaled symmetrical train model composed by two half cars, Reynolds Average Navier-stokes (RANS) equations and Shear Stress Transfer (SST) k-ω turbulence model are adopted to simulate the aerodynamic performance of the train with plate, aerodynamic drag dependence of the single parameter of the plate (shape, area, angle, position and number) is analyzed, and the identification research of the main aerodynamic parameters of plate is also carried out. The numerical settings used in this paper is verified by wind tunnel test data. Results show that the braking plate with aspect ratio of 1 has better performance on aerodynamic drag. The area, opening angle and number of plates are basically positively correlated with the total aerodynamic drag of the target car and plate. Arranging plates at the downstream of the vehicle is a good method of raising total aerodynamic drag. Within the range of plate parameter design in this paper, by using orthogonal design of experiment and method of range analysis and analysis of variance, the influence degrees of plate parameters on aerodynamic drag are determined, and the order is number, area and opening angle of plate. The research results provide theoretical support for the design and safe operation of high-speed train with aerodynamic braking plate.
随着列车速度的提高,制动片技术在列车高速段有着良好的应用前景。基于由两节半车厢组成的1/8比例对称列车模型,采用雷诺平均Navier-stokes(RANS)方程和剪切应力传递(SST)k-ω湍流模型模拟了带板列车的气动性能,分析了板的单个参数(形状、面积、角度、位置和数量)的气动阻力依赖性,并对板的主要气动参数进行了识别研究。本文中使用的数值设置通过风洞试验数据进行了验证。结果表明,纵横比为1的制动片具有较好的气动阻力性能。板的面积、开角和数量与目标车和板的总气动阻力基本呈正相关。将板布置在车辆的下游是提高总空气动力学阻力的好方法。在本文的板参数设计范围内,采用正交试验设计和极差分析方差分析方法,确定了板参数对气动阻力的影响程度,其顺序为板的数量、面积和开度。研究结果为采用气动制动板的高速列车的设计和安全运行提供了理论支持。
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引用次数: 1
Flexible Optimal Model and Algorithm for Track Utilization in High-speed Railway Stations 高速铁路车站轨道利用柔性优化模型与算法
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac057
Quan Gao, Yinggui Zhang, Zhiya Chen, Yuan Chen
Track utilization is the most important technical operation in high-speed railway stations. It's an effective way to take flexible management based on dispatchers’ decision preferences into consideration for making track utilization plans to relieve the influence caused by unmeasurable unstructured factors. Thus, based on flexible management concept and taken the flexible optimal for track utilization in high-speed railway stations as the object, time and space occupation safety trajectories of arrival routes, departure routes and tracks are all analyzed. Then, taking following constraints into consideration, i.e. minimum safety time intervals for various routes and tracks occupation, space-time arc occupation and decision-makers’ preferences, a flexible optimal model for track utilization in high-speed railway stations are established to maximize its balance and robustness and to minimize its volatility at the same time. Further, a flexible optimal solution based on a simulated annealing algorithm is designed to make a safety track utilization plan in high-speed railway stations integrating the dispatchers’ decision preference. The results gained from given experiments show that the proposed methodology can effectively make satisfied safety track utilization plans based on decision-makers’ preferences, which can improve its balance and robustness level significantly. Meanwhile, its volatility can be reduced as much as possible caused by flexible management based on artificial intervention to ensure the relative stability of the plan.
轨道利用是高铁车站最重要的技术操作。在制定轨道利用计划时,考虑调度员决策偏好的柔性管理,是缓解不可测量的非结构化因素影响的有效途径。因此,基于柔性管理理念,以高铁车站轨道利用柔性优化为目标,分析了到达路线、出发路线和轨道的时间和空间占用安全轨迹。然后,在考虑各路线、轨道占用的最小安全时间间隔、时空弧占用和决策者偏好等约束条件下,建立了高速铁路车站轨道利用的柔性优化模型,使其平衡性和鲁棒性最大化,同时使其波动性最小化。在此基础上,设计了一种基于模拟退火算法的柔性最优解,综合调度人员的决策偏好制定高铁车站安全轨道利用计划。实验结果表明,该方法能有效地根据决策者的偏好制定出满意的安全轨道利用方案,显著提高了其平衡性和鲁棒性水平。同时,通过人为干预的灵活管理,尽可能降低其波动性,保证计划的相对稳定性。
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引用次数: 0
Railway switch fault diagnosis based on Multi heads Channel Self Attention, Residual Connection and Deep CNN 基于多头通道自关注、残差连接和深度CNN的铁路道岔故障诊断
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac045
Xirui Chen, Hui Liu, Zhu Duan
A novel switch diagnosis method based on self-attention and residual deep Convolutional Neural Networks (CNN) is proposed. Because of the imbalanced dataset, the Kmeans synthetic minority oversampling technique (SMOTE) is applied to balancing the dataset at first. Then, the deep CNN is utilized to extract local features from long power curves, and the residual connection is performed to handle the performance degeneration. In the end, the Multi-heads Channel Self Attention focuses on those important local features. The ablation and comparison experiments are applied to verifying the effectiveness of the proposed methods. With the residual connection and Multi-heads Channel Self Attention, the proposed method has achieved an accuracy of 99.83% impressively. The t-SNE based visualizations for features of the middle layers enhance the trustworthiness.
提出了一种基于自注意和残差深度卷积神经网络(CNN)的开关诊断新方法。由于数据集不平衡,首先采用Kmeans合成少数过采样技术(SMOTE)对数据集进行平衡。然后,利用深度CNN从长功率曲线中提取局部特征,并进行残差连接来处理性能退化。最后,多头通道的自我关注集中在那些重要的局部特征上。通过烧蚀实验和对比实验验证了所提方法的有效性。在残差连接和多头通道自注意的情况下,该方法的准确率达到了99.83%。基于t-SNE的中间层特征可视化增强了可信度。
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引用次数: 0
Modeling medium and long term purchasing plans for environment-oriented container truck: a case study of yangtze river port 面向环境的集装箱卡车中长期采购计划建模——以长江港口为例
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac043
Shuai Li, Weijia Wu, Xiaofeng Ma, Ming Zhong, M. Safdar
Transportation sector is the most significant contributor to anthropogenic greenhouse gas (GHG) emissions. Particularly, maritime transportation, which is predominantly powered by fossil-fuel engines, accounts for more than 90% of world freight movement and emits 3% of global carbon dioxide (CO2) emissions. China is the world's largest emitter of CO2 and plays a key role in mitigating global climate change. In order to tackle this pressing concern, this study analyzes the port's throughput, the current number of trucks, and their emissions during the container truck purchasing process. While the previous studies about container truck purchasing plans mostly focused on the trucks' price and port needs. The objective of this study is to minimize the total cost of a port's inland transportation using optimization technique such as the interval uncertainty planning model to convert container truck emissions into social costs. This study considers the port of Yangtze as a case study. This study has designed two scenarios. (i) The base scenario (business-as-usual (BAU)) is used to quantify the relationship between pollutant emissions and system cost. In the base scenario, no environmental control facilities are used during the planning period, and there is no need to purchase new energy container trucks (ii) Expected scenario, referred to as (scenario A), for three planning periods. In scenario A, the emissions levels are required to remain at the same level as the first planning period during the whole planning period. By solving the above model, the number of all truck types, system cost, container throughput, and truck emissions in the port area were analyzed. The results showed that if no emission reduction control measures are implemented in the next 9 years, the growth rate of pollutants in the port area can be exceeded up to 20%. In addition, The findings showed clearly that truck emissions are reduced by purchasing new energy trucks and restricting the number of fossil-fuel (diesel) trucks. This study could also help to minimize system costs associated with port planning and management.
运输部门是造成人为温室气体排放的最重要因素。特别是,主要由化石燃料发动机提供动力的海上运输占世界货运量的90%以上,排放量占全球二氧化碳排放量的3%。中国是世界上最大的二氧化碳排放国,在缓解全球气候变化方面发挥着关键作用。为了解决这一紧迫问题,本研究分析了港口的吞吐量、当前卡车数量及其在集装箱卡车采购过程中的排放量。而以往关于集装箱卡车采购计划的研究大多集中在卡车的价格和港口需求上。本研究的目的是使用优化技术(如区间不确定性规划模型)将集装箱卡车排放转化为社会成本,最大限度地降低港口内陆运输的总成本。本研究以长江港为个案。本研究设计了两个场景。(i) 基本情景(照常营业(BAU))用于量化污染物排放和系统成本之间的关系。在基本情景中,规划期内不使用环境控制设施,也不需要购买新能源集装箱卡车(ii)三个规划期的预期情景,即(情景A)。在情景A中,要求在整个规划期内,排放水平保持在与第一个规划期相同的水平。通过求解上述模型,分析了港区内所有卡车类型的数量、系统成本、集装箱吞吐量和卡车排放量。结果表明,如果在未来9年内不实施减排控制措施,港区污染物的增长率可能超过20%。此外,研究结果清楚地表明,通过购买新能源卡车和限制化石燃料(柴油)卡车的数量,可以减少卡车的排放。这项研究也有助于最大限度地减少与港口规划和管理相关的系统成本。
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引用次数: 4
Left turn across path and opposite direction accidents in China: CIDAS accident study 中国的左转弯和反方向事故:CIDAS事故研究
IF 2.2 4区 工程技术 Q2 TRANSPORTATION SCIENCE & TECHNOLOGY Pub Date : 2022-12-21 DOI: 10.1093/tse/tdac070
Y. Chen, Christian Buerger, Miao Lin, Xudong Li, Volker Labenski, Haixia Jin, Hai Wang, Yang Liu, Tsuyoshi Ino, Harald Feifel, Tian Tan, Fangrong Chang
Left Turn Across Path with Opposite Direction (LTAP/OD) conflicts are one of the most common crash types at intersections. The research aims to reveal the general and dynamic information about the conflict for the most relevant street layouts for each conflict configuration of the LTAP/OD accidents involving passenger cars, motorcycles and Ebikes. The analysis was based on 276 LTAP/OD accidents collected by China In-Depth Accident Study (CIDAS 2011–2019). The LTAP/OD accidents include 44 car-to-car conflicts, 157 car-to-motorcycle conflicts and 75 car-to-Ebike conflicts. Most of accidents belonging to three types were observed at the W0 street layout without green belt separating the oncoming lane and no offset lane between the turning car and the oncoming traffic, the main distance between both vehicles in the beginning of the critical situation being about four meters, occurring in the clear day with no rain and at junctions lighted either because of daylight or based on street lighting. In terms of the turning car initial speed, the range is between 15-30 km/h for most car-to-car and car-to-motorcycle accidents but 30-40 km/h for most car-to-Ebike accidents. As for the collision speed, this range is between 10 and 20 km/h for car-to-car and car-to-Ebike accidents and between 10 and 25 km/h for car-to-motorcycle crashes. Based on the distributions of objective motorcycles’ and Ebike's positions in collisions with passenger cars, the maximum longitudinal distance is 60 m for both two types of accidents and the maximum lateral distance ranges from -20 m to 20 m and from -15 m to 15 m, respectively.
反向左转(LTAP/OD)冲突是十字路口最常见的碰撞类型之一。本研究旨在揭示涉及客车、摩托车和电动自行车的LTAP/OD事故的每个冲突配置的最相关街道布局的冲突的一般和动态信息。该分析基于中国深度事故研究(CIDAS 2011-2019)收集的276起LTAP/OD事故。LTAP/OD事故包括44起车与车冲突、157起车与摩托车冲突和75起车与电动自行车冲突。属于三种类型的事故大多发生在W0街道布局上,没有将迎面而来的车道分隔开的绿化带,转弯车辆和迎面而来车辆之间也没有偏移车道,在危急情况开始时,两辆车之间的主要距离约为4米,发生在晴朗无雨的日子里,在因日光或基于街道照明而照明的路口。就转弯汽车的初始速度而言,大多数汽车对汽车和汽车对摩托车事故的速度范围在15-30公里/小时之间,但大多数汽车对电动自行车事故的速度为30-40公里/小时。至于碰撞速度,对于汽车对汽车和汽车对电动自行车的事故,这个范围在10到20公里/小时之间,对于汽车和摩托车的碰撞,这个范围是10到25公里/小时。根据目标摩托车和电动自行车在与客车碰撞中的位置分布,两种事故的最大纵向距离均为60米,最大横向距离分别为-20米至20米和-15米至15米。
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引用次数: 1
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Transportation Safety and Environment
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