Journal of Traffic and Transportation Engineering-English Edition最新文献

A systematic review of digital twins for electric vehicles 电动汽车数字孪生系统回顾

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-10-01 DOI: 10.1016/j.jtte.2024.04.004

Shrey Verma , Ankush Sharma , Binh Tran , Damminda Alahakoon

The transport sector emits 18% of global CO₂. Industry and consumers must adopt green mobility to reduce emissions and climate change. This will help achieve sustainability by improving efficiency and reducing greenhouse gas emissions. Thus, smart electric vehicles (SEVs) have emerged. Digital twins concept and technology may help launch SEVs to the market by analysing and optimising supporting infrastructure. This work aims to fill in the gaps between different pieces of research by giving a full review from a technical and scientifically neutral point of view. The study looks at how digital twin technology can be used in smart car systems by looking at its promise and the hurdles faced. Based on a comprehensive literature survey, this is the first in-depth look at how digital twin technology can be used in smart electric cars. The review has been organised into specific areas of the smart vehicle system, such as drive train system battery management system, driver assistance system, vehicle health monitoring system, vehicle power electronics. This review goes into detail about each component of the car to provide an overall view of the smart vehicle system as a whole. This review makes it easier to understand how digital twin technology can be utilized into each area from a scientific point of view. Lastly, the work looks at the technological and economic impact of digital twin technology, which will make considerable changes in car manufacturing processes, as well as help address current obstacles in utilizing advanced technologies.

交通部门排放的二氧化碳占全球总量的 18%。工业和消费者必须采用绿色交通，以减少排放和气候变化。这将有助于通过提高效率和减少温室气体排放来实现可持续发展。因此，智能电动汽车（SEVs）应运而生。数字孪生概念和技术可通过分析和优化配套基础设施，帮助将智能电动汽车推向市场。这项工作旨在从技术和科学中立的角度进行全面审查，从而填补不同研究之间的空白。本研究通过审视数字孪生技术的前景和面临的障碍，探讨如何将其应用于智能汽车系统。在全面文献调查的基础上，本研究首次深入探讨了数字孪生技术如何应用于智能电动汽车。综述按智能汽车系统的具体领域进行了分类，如传动系统、电池管理系统、驾驶员辅助系统、车辆健康监测系统、车辆电力电子系统等。本综述详细介绍了汽车的每个组件，以提供智能汽车系统的整体视图。通过回顾，我们更容易从科学的角度理解如何将数字孪生技术应用到各个领域。最后，本研究还探讨了数字孪生技术对技术和经济的影响，它将极大地改变汽车制造流程，并有助于解决目前在利用先进技术方面存在的障碍。

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引用次数: 0

Architecture, application, and prospect of digital twin for highway infrastructure 公路基础设施数字孪生的架构、应用和前景

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-10-01 DOI: 10.1016/j.jtte.2024.03.003

Yue Wang , Huimin Wang , Weiming Wang , Shizhao Song , Xin Fu

The years we are experiencing are often identified as those of the age of digital technologies, where “digital” is commonly associated with intelligence, efficiency, and convenience. The emergence of digital technologies has significantly impacted and transformed various aspects of our society compared to the past. In this panorama, some arising questions regard transportation infrastructure systems and, first of all, highway infrastructure. This research focuses on one central issue: how highways fit into this digital revolution. Actually, the work in this paper can be described as follows. Although there are many different theoretical model systems for the architecture of the digital twin, we have chosen to review the main body of research on the digital twin in highway infrastructure based on a relatively well-established modeling framework, the five-dimensional model of the digital twin. After discussing the components of the digital twin for highway infrastructure's five-dimensional model, the paper reviews some innovative technologies that make these items effective. In addition to this, the digital twin maturity level of highway infrastructure and the MBSE-based (model-based systems engineering) digital twin model for highway are also discussed in this paper. Therefore, the paper provides a bird's eye view of this extremely dynamic technology for a new system of intelligent highways and discusses some of their criticalities and strengths, allowing for the optimization and development of new transportation functions and services, improving the adaptability of highways to the digital revolution.

我们正在经历的岁月通常被认为是数字技术时代，"数字 "通常与智能、高效和便捷联系在一起。与过去相比，数字技术的出现极大地影响和改变了我们社会的各个方面。在这一全景中，一些新出现的问题涉及交通基础设施系统，首先是公路基础设施。本研究主要关注一个核心问题：高速公路如何融入这场数字革命。实际上，本文的工作可以描述如下。尽管数字孪生架构有许多不同的理论模型系统，但我们还是选择了一个相对成熟的建模框架--数字孪生的五维模型--来回顾公路基础设施中数字孪生的主要研究内容。在讨论了公路基础设施五维模型数字孪生的组成部分后，本文回顾了使这些项目有效的一些创新技术。此外，本文还讨论了公路基础设施数字孪生的成熟度以及基于 MBSE（基于模型的系统工程）的公路数字孪生模型。因此，本文对这一极具活力的技术进行了鸟瞰，为新的智能高速公路系统提供了一个视角，并讨论了它们的一些关键点和优势，从而可以优化和开发新的交通功能和服务，提高高速公路对数字革命的适应性。

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引用次数: 0

RAP chunks produced in cold milling operation of asphalt pavement: Evaluation, mechanism, and engineering investigation in China 沥青路面冷铣刨机作业中产生的 RAP 块：中国的评估、机理和工程研究

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-10-01 DOI: 10.1016/j.jtte.2024.03.004

Yuquan Yao , Jiangang Yang , Jie Gao , Mulian Zheng , Liang Song , Jing Xu , Chen Sun

Cold milling is a widely used method for rehabilitating asphalt pavement, generating reclaimed asphalt pavement (RAP) chunks. Within this process, aggregates within the asphalt pavement will be crushed, forming RAP agglomerates and aggregate breakdown. However, the mechanism of these phenomena has remained unclear, and a unified evaluation method has yet to be established. In this study, RAP agglomeration and aggregate fragmentation were characterized, five distinct methods were systematically assessed, and the mechanism of RAP agglomeration and breakdown was analyzed by discrete element method (DEM) simulation based on setting different particle contact parameters, then followed by a mechanical analysis, and demonstrated in engineering. The results revealed that both agglomeration and aggregate breakdown occur within RAP particles of various sizes, with the five methods showing similar trends in quantifying these effects. Through DEM simulations and mechanical analyses, the aggregate breakdown predominantly occurs at the cutter's motion trajectory of the cutter and during crack propagation, while agglomeration was mainly related to the sliding surface's area. The milling speed and depth positively impact RAP agglomeration, while negatively affecting aggregate breakdown, and milling drum speed exerts minimal influence on these phenomena. RAP agglomeration varies considerably in different engineering projects, and cold milling parameters should be determined based on the material composition of the asphalt pavement and design requirements to control agglomeration and breakdown rates of RAP.

冷铣刨机是一种广泛使用的修复沥青路面的方法，可产生再生沥青路面（RAP）大块。在此过程中，沥青路面中的集料会被压碎，形成 RAP 团块和集料破碎。然而，这些现象的机理尚不清楚，统一的评估方法也尚未建立。本研究对 RAP 结团和集料破碎进行了表征，系统地评估了五种不同的方法，并在设置不同颗粒接触参数的基础上，通过离散元法（DEM）模拟分析了 RAP 结团和集料破碎的机理，然后进行了力学分析，并在工程中进行了演示。结果表明，在不同大小的 RAP 颗粒中都会发生团聚和聚合破裂，五种方法在量化这些效应方面表现出相似的趋势。通过 DEM 模拟和力学分析，骨料破碎主要发生在铣刀的运动轨迹和裂纹扩展过程中，而聚结主要与滑动面的面积有关。铣削速度和深度对 RAP 结块产生积极影响，而对骨料破碎产生消极影响，铣削滚筒速度对这些现象的影响很小。在不同的工程项目中，RAP 的结块情况差异很大，应根据沥青路面的材料组成和设计要求确定冷铣刨机参数，以控制 RAP 的结块和破碎率。

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引用次数: 0

Potential applications for composite utilization of rubber and plastic in asphalt pavements: A critical review 沥青路面中橡胶和塑料复合利用的潜在应用：严格审查

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-10-01 DOI: 10.1016/j.jtte.2024.04.005

Haibin Li , Lichang Zhou , Yuhang Cai , Yongfei Zhang , Bature Auwal Ibrahim , Zixuan Feng , Liyun Tang , Zhigang Li , Fayong Yang

Waste plastics and rubber have always posed a threat to the environment and a great challenge for disposal. The use of these two waste materials as modifiers for road asphalt provides new road asphalt binders and at the same time provides a new way for waste material resource treatment. Rubber-modified asphalt and plastic-modified asphalt have received widespread attention due to their green and low-carbon characteristics and some performance advantages, but there are still some performance shortcomings that hinder their promotion and application. In order to continue to explore the application of waste materials in the field of road engineering, combined with the performance advantages of both, many scholars began to study the rubber-plastic composite modified asphalt (RPCMA). Therefore, this paper reviewed the different types of waste rubber and plastic, the comprehensive performance of different types of asphalt and its mixture performance, analyzed the modification mechanism of rubber-plastic composite modified asphalt and its performance changes. The results show that rubber-plastic composite modified asphalt is mostly prepared by directly adding modified materials. However, the pretreatment or melt granulation of rubber and plastic will make the performance of rubber-plastic modified asphalt has improved. There is a mutual promotion mechanism between rubber and plastic in asphalt, which makes the performance of rubber-plastic modified asphalt better than that of asphalt obtained by a single modification method (rubber modified asphalt or plastic modified asphalt). In some properties, it can be close to the commercial SBS modified asphalt. The performance of rubber and plastic composite modified asphalt at high temperature has been generally recognized by researchers, but its low-temperature performance is still controversial. Therefore, it is recommended to apply in high-temperature areas. Future work should focus on the development of composite modifiers with stable performance, low cost and ease of use, standardization of modification processes, improvement of low-temperature performance, and monitoring of road performance and environmental impact.

废塑料和废橡胶一直对环境构成威胁，也是处理过程中的巨大挑战。利用这两种废旧材料作为道路沥青改性剂，在提供新型道路沥青胶结料的同时，也为废旧材料资源化处理提供了一条新途径。橡胶改性沥青和塑料改性沥青因其绿色低碳的特点和一定的性能优势受到广泛关注，但仍存在一些性能缺陷，阻碍了其推广应用。为了继续探索废旧材料在道路工程领域的应用，结合二者的性能优势，许多学者开始研究橡胶塑料复合改性沥青（RPCMA）。为此，本文综述了不同类型废旧橡塑、不同类型沥青的综合性能及其混合料性能，分析了橡塑复合改性沥青的改性机理及其性能变化。结果表明，橡塑复合改性沥青多采用直接添加改性材料的方法制备。但橡塑预处理或熔融造粒会使橡塑改性沥青的性能得到改善。橡胶和塑料在沥青中存在相互促进的机理，使得橡塑改性沥青的性能优于单一改性方法（橡胶改性沥青或塑料改性沥青）制备的沥青。在某些性能上，它可以接近商品 SBS 改性沥青。橡塑复合改性沥青的高温性能已得到研究人员的普遍认可，但其低温性能仍存在争议。因此，建议在高温地区应用。今后的工作重点应放在开发性能稳定、成本低廉、使用方便的复合改性剂，规范改性工艺，提高低温性能，监测道路性能和环境影响等方面。

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引用次数: 0

Design equations for maximum stress concentration factors for concrete-filled steel tubular K-joints 混凝土填充钢管 K 型接头最大应力集中系数的设计方程

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-10-01 DOI: 10.1016/j.jtte.2022.07.007

Lei Jiang , Yongjian Liu , Neil A. Hoult , Xin Long , Wenshuai Wang

Stress concentration factors (SCFs) for welded tubular joints can be decreased by filling the chord with concrete leading to a longer fatigue life. However, there are currently no design formula available in guidelines to predict the SCF of concrete-filled circular hollow section (CFCHS) K-joints, thus limiting their applicability in bridge design. To address this gap, finite element models for CFCHS K-joints were developed and compared against test results to ensure their accuracy. Then, a comprehensive parametric study was conducted to establish relationships between maximum SCFs and four variables: brace-to-chord diameter ratio (β), chord diameter-to-thickness ratio (2γ), brace-to-chord thickness ratio (τ), and the angle between braces and chord (θ). A total of 480 FE models were examined under three loading conditions including brace and chord loading: balanced axial force, chord axial force, and chord bending. Design equations to predict the maximum SCF for CFCHS K-joints were established by multiple regression analyses of the numerical results. A comparison of maximum SCFs between circular hollow section (CHS) and CFCHS K-joints was made, and it was concluded that average reductions of 42% and 33% in maximum SCFs in CFCHS K-joints at the locations of the chord and brace were found compared to CHS joints for balanced axial force, respectively. Finally, a case study illustrating how to use the proposed equations for fatigue safety verification was presented.

通过在弦部填充混凝土可以降低焊接管状接头的应力集中系数（SCF），从而延长疲劳寿命。然而，目前还没有任何设计公式可用于预测混凝土填充圆形空心截面（CFCHS）K 型接头的应力集中系数，因此限制了其在桥梁设计中的应用。为了填补这一空白，我们开发了 CFCHS K 型连接件的有限元模型，并将其与测试结果进行比较，以确保其准确性。然后，进行了全面的参数研究，以确定最大 SCF 与四个变量之间的关系：支撑与弦直径比 (β)、弦直径与厚度比 (2γ)、支撑与弦厚度比 (τ)，以及支撑与弦之间的角度 (θ)。共有 480 个有限元模型在三种加载条件下进行了检验，包括支架和弦杆加载：平衡轴向力、弦杆轴向力和弦杆弯曲。通过对数值结果进行多元回归分析，建立了预测 CFCHS K 型关节最大 SCF 的设计方程。对圆形空心截面（CHS）和 CFCHS K 型接头的最大 SCF 进行了比较，得出的结论是，与 CHS 接头相比，CFCHS K 型接头在平衡轴向力下，弦杆和支撑位置的最大 SCF 平均分别降低了 42% 和 33%。最后，介绍了一个案例研究，说明如何使用所提出的公式进行疲劳安全验证。

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引用次数: 0

A review of China's automotive industry policy: Recent developments and future trends 中国汽车产业政策回顾：近期发展和未来趋势

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-10-01 DOI: 10.1016/j.jtte.2024.09.001

Yisong Chen, Xiaofang Dai, Pei Fu, Geng Luo, Peilong Shi

To promote the improvement and development of China's automotive industry policy, this study conducts a systematic review and hierarchical analysis of both domestic and international automotive industry policies. First, the automotive industry policies of the United States, Germany, South Korea, and Japan are summarized in terms of their industrial structure adjustment, technological innovation, taxes and financial subsidies, and infrastructure construction. Benchmarking the policies of international automotive industry powers provides a reference and basis for integrating their experiences in the formulation of China's automotive industry policy. Second, beginning with China's “Automotive Industry Policy” issued in 1994, the key automotive industry policies at different points in history and under different strategies are analyzed. Through policy adjustment and target setting, the changing focus through the historical development of China's automotive industry is determined, along with the development of the industry and technological progress. Then, from the perspectives of strategic planning, promotion and application, credit management, infrastructure, management standards, and standard systems, the advantages and disadvantages of current development policies for new energy and intelligent connected vehicles are clarified. The challenges and limitations of China's automotive industry policy are summarized, including a lack of investment in technology research and development, low level of infrastructure support, and insufficient consumer protection. China's automotive industry policy is then into three different historical stages: i) 1994 to 2008, ii) 2009 to 2013, and iii) 2014 to present; and the characteristics of each stage are summarized. Finally, based on China's national conditions and considering the future development trends of the international automotive industry, the study concludes that under the strong drivers of carbon peak and neutrality goals, China's future automotive industry policy should feature energy saving and emission reduction as the main goals. Independent innovation should be the main enabler, strengthening and supplementing the supply chain through intelligent connectivity.

为促进中国汽车产业政策的完善和发展，本研究对国内外汽车产业政策进行了系统梳理和分层分析。首先，从产业结构调整、技术创新、税收和财政补贴、基础设施建设等方面对美国、德国、韩国和日本的汽车产业政策进行了总结。对标国际汽车产业强国的政策，为中国汽车产业政策的制定提供了借鉴和经验整合的基础。其次，从 1994 年中国发布的《汽车产业政策》开始，分析了不同历史时期、不同战略下的主要汽车产业政策。通过政策调整和目标设定，确定了中国汽车产业历史发展中随着产业发展和技术进步而不断变化的重点。然后，从战略规划、推广应用、信用管理、基础设施、管理标准、标准体系等方面，阐明了当前新能源和智能网联汽车发展政策的优劣势。总结了中国汽车产业政策面临的挑战和局限性，包括技术研发投入不足、基础设施配套水平低、消费者保护力度不够等。然后，将中国的汽车产业政策分为三个不同的历史阶段：i) 1994 年至 2008 年，ii) 2009 年至 2013 年，iii) 2014 年至今；并总结了每个阶段的特点。最后，立足中国国情，结合国际汽车产业未来发展趋势，研究认为，在碳峰值和碳中和目标的强力驱动下，中国未来的汽车产业政策应以节能减排为主要目标。自主创新应成为主要推动力，通过智能互联加强和补充供应链。

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引用次数: 0

Use of Wehner-Schulze machine to evaluate pavement skid resistance: A review 使用 Wehner-Schulze 机器评估路面抗滑性：综述

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-10-01 DOI: 10.1016/j.jtte.2024.04.006

Francesco Canestrari, Eugenio Mariani, Lorenzo Paolo Ingrassia

Pavement skid resistance plays a crucial role in ensuring road safety and avoiding accidents. In the past, the laboratory evaluation of the skid resistance was carried out by studying only the coarse aggregates of the wearing course. To overcome this drawback, the Wehner-Schulze (WS) machine was developed in Germany in the 1960s. This equipment, composed of a polishing unit and a measuring unit, has great potential in predicting pavement skid resistance and its evolution over time, but is still little known in the pavement community (especially outside Europe). For these reasons, there is a need of a comprehensive review of the existing technical-scientific literature concerning the use of the WS machine. Specifically, this paper focuses on the main factors affecting the skid resistance in WS tests, the correlation of WS data with other laboratory test methods and with field skid resistance/polishing, and the available prediction models that have been validated through WS measurements. The critical analysis of the existing literature highlights that it is possible to correlate WS data with typical skid resistance field measurements as well as WS polishing with traffic polishing, but further efforts are needed in this regard. Future work should focus especially on open-graded mixtures and innovative asphalt mixtures (e.g., containing recycled materials and additives). From the perspective of pavement management, based on a theoretical background, the WS test results could be used as starting point for simplified prediction models of the in-situ skid resistance.

路面抗滑性在确保道路安全和避免事故方面起着至关重要的作用。过去，实验室对路面抗滑性的评估仅通过研究磨耗层的粗集料来进行。为了克服这一缺点，20 世纪 60 年代德国开发出了 Wehner-Schulze (WS) 设备。该设备由抛光单元和测量单元组成，在预测路面抗滑性及其随时间的变化方面具有巨大潜力，但在路面界（尤其是欧洲以外地区）仍鲜为人知。因此，有必要对有关使用 WS 机器的现有技术科学文献进行全面审查。具体而言，本文重点关注影响 WS 试验抗滑性的主要因素、WS 数据与其他实验室试验方法和现场抗滑性/抛光的相关性，以及通过 WS 测量验证的现有预测模型。对现有文献的批判性分析突出表明，有可能将 WS 数据与典型的抗滑性现场测量结果以及 WS 抛光与交通抛光相关联，但在这方面还需要进一步努力。未来的工作应特别关注开放式级配混合料和创新型沥青混合料（如含有回收材料和添加剂）。从路面管理的角度来看，基于理论背景，WS 测试结果可作为简化原位抗滑性预测模型的起点。

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引用次数: 0

Assessing the risk of pedestrian crossing behavior on suburban roads using structural equation model 利用结构方程模型评估郊区道路上行人横穿马路行为的风险

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-10-01 DOI: 10.1016/j.jtte.2023.12.001

Shahrbanoo Kavianpour , Farshidreza Haghighi , Abbas Sheykhfard , Subasish Das , Grigorios Fountas , Mohammad Mehdi Oshanreh

While pedestrian crashes on suburban roads have received more attention over recent years, the role of pedestrian crossing risk in areas adjacent to pedestrian crossing facilities, such as pedestrian overpasses, has been neglected. Most pedestrians in suburban areas tend to avoid pedestrian overpasses, exhibiting crossing behaviors that increase the likelihood of pedestrian-involving crashes. As a result of the presence of overpasses, drivers may think that there are no pedestrians in the surroundings, so they choose a speed based only on the prevailing traffic and road environment without accounting for potential interactions with pedestrians. Consequently, crashes will occur, with pedestrians typically being the most seriously affected casualties. In this study, using video recordings from a suburban road in Amol-Babol, Iran, the risk of pedestrian crossing behavior in areas near pedestrian overpasses is investigated. The speed selection behavior of drivers in these areas has also been examined using speedometer cameras. To quantify the level of risk for pedestrians when interacting with approaching vehicles during the crossing movements, the post encroachment time (PET) was used as a surrogate safety measure. Based on critical thresholds of PET, three different risk levels were identified using a K-means algorithm: high, medium, and low risk. To identify the elements affecting the risk of pedestrian crossing behavior, structural equation models were estimated for all three risk levels. The results showed that human factors, relating to both drivers and pedestrians, have a dominant impact on pedestrian safety, especially in high and medium risk contexts. Road and vehicle factors were also found to have statistically observable effects on pedestrian safety, but to a milder extent compared to human factors. The findings of this study highlight the need for intervening in several aspects of vehicle-pedestrian interactions with critical importance for pedestrian safety, including road users’ performance and compliance, state of alertness, and interaction with road infrastructure.

近年来，郊区道路上的行人碰撞事故受到越来越多的关注，但行人过街风险在行人过街设施（如人行天桥）附近地区的作用却一直被忽视。郊区的大多数行人都倾向于避开人行过街天桥，他们的过街行为增加了发生行人碰撞事故的可能性。由于立交桥的存在，驾驶员可能会认为周围没有行人，因此只根据当时的交通和道路环境选择车速，而不考虑可能与行人发生的相互作用。因此，碰撞事故就会发生，而行人通常是受影响最严重的伤亡者。本研究利用伊朗阿莫尔-巴波尔郊区道路的视频记录，调查了行人过街行为在人行天桥附近区域的风险。此外，还使用测速照相机对这些地区驾驶员的速度选择行为进行了研究。为了量化行人在横穿马路时与驶来车辆相互作用的风险水平，使用了侵占后时间（PET）作为替代安全措施。根据 PET 的临界阈值，使用 K-means 算法确定了三种不同的风险等级：高风险、中风险和低风险。为了确定影响行人过马路行为风险的因素，对所有三个风险等级进行了结构方程模型估算。结果表明，与驾驶员和行人有关的人为因素对行人安全有主要影响，尤其是在高风险和中风险情况下。从统计学角度看，道路和车辆因素对行人安全也有影响，但与人为因素相比，影响程度较轻。这项研究的结果突出表明，有必要对车辆与行人互动中对行人安全至关重要的几个方面进行干预，包括道路使用者的表现和遵守情况、警觉状态以及与道路基础设施的互动。

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引用次数: 0

Comparison and assessment of carbon dioxide emissions between alkali-activated materials and OPC cement concrete 碱活性材料与 OPC 水泥混凝土二氧化碳排放量的比较与评估

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-10-01 DOI: 10.1016/j.jtte.2023.07.011

Peiliang Cong, Ruyan Du, Huanlin Gao, Zhihui Chen

Geopolymer concrete (GPC) has been developed as a sustainable alternative to traditional cement-based concrete using industrial waste materials. Thus, reducing greenhouse gas emissions in concrete production can be expected. This study employed the life cycle assessment (LCA) method to evaluate geopolymer concrete's cost and life-cycle carbon dioxide (CO₂) emissions. Moreover, the critical transportation radius of the geopolymer is estimated. Then, evaluation results were compared with ordinary Portland cement (OPC), considering three concrete construction methods: cast-in-place, ready-mixed, and precast. In particular, the service life of two types of concrete in sulfuric acid environments is considered. Compared with OPC concrete, the results show that geopolymer concretes can significantly reduce the cost and CO₂ emissions when one or a small amount of alkali activator is used or alkali-containing materials are used to replace some alkali activators. However, the advantages would be reversed by the rising alkali dosages, which account for cost increases and carbon emissions. When considering the service life in special environments, geopolymer concrete in sulfuric acid environments corresponds to fewer carbon emissions, 94%–97% decreased compared with OPC concrete. Finally, compared with OPC concrete, the newly developed limestone calcined clay cement (LC3) avoids high-temperature calcination and dramatically reduces carbon dioxide emissions. Compared to OPC concrete, LC3 concrete has a 19% reduction in CO₂ emissions. And geopolymer concrete that takes alkali-activate materials for superseding alkalis also produces less carbon dioxide emissions. In particular, CO₂ emissions from FA-SF geopolymer concrete are approximately 50% lower than OPC concrete. In addition, the use of alkali activators significantly weakens the cost advantage of geopolymers. But after accounting for waste disposal costs, the average net cost of fly ash-based geopolymer concrete can be more than 30% lower than that of OPC concrete. The average net cost of slag-based geopolymer concrete is 7%–45% lower than that of OPC concrete. The findings of this work provide the basis for further development of geopolymer concretes obeyed environmental protection.

土工聚合物混凝土（GPC）是利用工业废料作为传统水泥混凝土的可持续替代品而开发的。因此，有望减少混凝土生产过程中的温室气体排放。本研究采用生命周期评估（LCA）方法对土工聚合物混凝土的成本和生命周期二氧化碳（CO2）排放量进行了评估。此外，还估算了土工聚合物的临界运输半径。然后，将评估结果与普通硅酸盐水泥（OPC）进行了比较，并考虑了三种混凝土施工方法：现浇、预拌和预制。特别是考虑了两种混凝土在硫酸环境中的使用寿命。结果表明，与 OPC 混凝土相比，当使用一种或少量碱活化剂，或使用含碱材料替代某些碱活化剂时，土工聚合物混凝土可显著降低成本和二氧化碳排放量。然而，碱用量的增加会导致成本上升和碳排放量增加，从而使上述优势发生逆转。考虑到特殊环境下的使用寿命，土工聚合物混凝土在硫酸环境下的碳排放量比 OPC 混凝土少 94%-97%。最后，与 OPC 混凝土相比，新开发的石灰石煅烧粘土水泥（LC3）避免了高温煅烧，大大减少了二氧化碳排放量。与 OPC 混凝土相比，LC3 混凝土的二氧化碳排放量减少了 19%。而采用碱活性材料取代碱的土工聚合物混凝土也减少了二氧化碳排放量。其中，FA-SF 土工聚合物混凝土的二氧化碳排放量比 OPC 混凝土低约 50%。此外，碱活化剂的使用大大削弱了土工聚合物的成本优势。但在考虑废物处理成本后，粉煤灰基土工聚合物混凝土的平均净成本可比 OPC 混凝土低 30% 以上。矿渣基土工聚合物混凝土的平均净成本比 OPC 混凝土低 7%-45%。这些研究结果为进一步开发符合环保要求的土工聚合物混凝土提供了依据。

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引用次数: 0

Efficiency-oriented vehicle relocation of shared autonomous electric fleet in station-based car-sharing system 基于站点的汽车共享系统中以效率为导向的共享自主电动车队的车辆迁移

IF 7.4 2区工程技术 Q1 ENGINEERING, CIVIL

Journal of Traffic and Transportation Engineering-English Edition

Pub Date : 2024-08-01 DOI: 10.1016/j.jtte.2022.12.003

Ning Wang , Hangqi Tian , Jiahui Guo , Huahua Wu , Jian Lyu

Long waiting delays for users and significant imbalances in vehicle distribution are bothering traditional station-based one-way electric car-sharing system operators. To address the problems above, a “demand forecast-station status judgement-vehicle relocation” multistage dynamic relocation algorithm based on the automatic formation cruising technology was proposed in this study. In stage one, a novel trip demand forecast model based on the long short-term memory network was established to predict users' car-pickup and car-return order volumes at each station. In stage two, a dynamic threshold interval was determined by combining the forecast results with the actual vehicle distribution among stations to evaluate the status of each station. Then vehicle-surplus, vehicle-insufficient, vehicle-normal stations, and the number of surplus or insufficient vehicles for each station were counted. In stage three, setting driving mileage and carbon emission as the optimization objectives, an integer linear programming mathematical model was constructed and the optimal vehicle relocation scheme was obtained by the commercial solver Gurobi. Setting 43 stations and 187 vehicles in Jiading District, Shanghai, China, as a case study, results showed that rapid vehicle rebalancing among stations with minimum carbon emissions could be realized within 15 min and the users’ car-pickup and car-return demands could be fully satisfied without any refusal.

用户等待时间过长、车辆分布严重失衡等问题困扰着传统的站点式单向电动汽车共享系统运营商。针对上述问题，本研究提出了基于自动编队巡航技术的 "需求预测-站点状态判断-车辆调配 "多阶段动态调配算法。第一阶段，建立基于长短期记忆网络的新型出行需求预测模型，预测用户在各站点的取车和还车订单量。第二阶段，结合预测结果和各站点的实际车辆分布情况，确定动态阈值区间，以评估各站点的状态。然后统计车辆过剩站、车辆不足站、车辆正常站以及每个站点的过剩或不足车辆数。第三阶段，以行驶里程和碳排放为优化目标，构建了整数线性规划数学模型，并通过商业求解器 Gurobi 获得了最优车辆迁移方案。以上海市嘉定区 43 个站点、187 辆车为例，结果表明，在 15 分钟内可以实现碳排放量最小的站点间车辆快速重新配置，用户的取车和还车需求可以得到充分满足，没有任何拒绝现象。

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引用次数: 0