| 1. |
- Bie, Yiming, et al.
(author)
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Dynamic headway control for high-frequency bus line based on speed guidance and intersection signal adjustment
- 2020
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In: Computer-Aided Civil and Infrastructure Engineering. - : Wiley. - 1093-9687 .- 1467-8667. ; 35:1, s. 4-25
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Journal article (peer-reviewed)abstract
- Computer-Aided Civil and Infrastructure Engineering To prevent bus bunching, a dynamic headway control method in the V2I (vehicle to infrastructure) environment for a high-frequency route with bus lane is developed. Bus operating speed guidance on the mid-blocks and intersection signal adjustment are two main strategies in the proposed method. A forecasting model of bus travel time under the dynamic control method is developed. The objective function is set up by taking into account differences between actual bus headways and dispatching headways, and the scaling ratios of intersection cycle lengths. The optimization model is solved using genetic algorithm. The proposed method is applied to a real bus route in Meihekou city, China, and compared with the current control plan as well as holding strategy. Results show that the proposed method can reduce bus headway deviations in all investigating periods; negative impacts on cars can be limited by setting reasonable values for the parameters.
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| 2. |
- Duan, Yuzhou, et al.
(author)
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Optimising total entry delay at roundabouts with unbalanced flow: A dynamic strategy for smart metering
- 2019
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In: IET Intelligent Transport Systems. - : Institution of Engineering and Technology (IET). - 1751-9578 .- 1751-956X. ; 13:3, s. 485-494
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Journal article (peer-reviewed)abstract
- Modern roundabouts are widely used at intersections with light traffic, generally providing safety and other advantages. However, large entry delays are often observed at roundabouts with unbalanced flow patterns, even though the entry traffic flow is not high. A metering signal-based strategy is examined to mitigate the above problems. A mathematical optimisation model is formulated firstly with the objective of minimising the total entry delay, subject to the metering signal thresholds. Then a solution algorithm based on VISSIM simulation is developed. Finally, a case study is carried out to testify the feasibility and applicability of the proposed model. Extended scenarios analyses under different levels of approach volume, different demand combinations and different proportions of right-turn vehicles (left-side driving) are also conducted. Results show that the methodology can effectively improve the operational performance, and a delay reduction of up to 25.7% can.
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| 3. |
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| 4. |
- Ma, Tao, et al.
(author)
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Genomic insights into salt adaptation in a desert poplar
- 2013
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 4, s. 2797-
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Journal article (peer-reviewed)abstract
- Despite the high economic and ecological importance of forests, our knowledge of the genomic evolution of trees under salt stress remains very limited. Here we report the genome sequence of the desert poplar, Populus euphratica, which exhibits high tolerance to salt stress. Its genome is very similar and collinear to that of the closely related mesophytic congener, P. trichocarpa. However, we find that several gene families likely to be involved in tolerance to salt stress contain significantly more gene copies within the P. euphratica lineage. Furthermore, genes showing evidence of positive selection are significantly enriched in functional categories related to salt stress. Some of these genes, and others within the same categories, are significantly upregulated under salt stress relative to their expression in another salt-sensitive poplar. Our results provide an important background for understanding tree adaptation to salt stress and facilitating the genetic improvement of cultivated poplars for saline soils.
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| 5. |
- Tong, Pei, et al.
(author)
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Optimal route design of electric transit networks considering travel reliability
- 2021
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In: Computer-Aided Civil and Infrastructure Engineering. - : Wiley. - 1093-9687 .- 1467-8667. ; 36:10, s. 1229-1248
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Journal article (peer-reviewed)abstract
- Travel reliability is the most essential determinant for operating the transit system and improving its service level. In this study, an optimization model for the electric transit route network design problem is proposed, under the precondition that the locations of charging depots are predetermined. Objectives are to pursue maximum travel reliability and meanwhile control the total cost within a certain range. Constraints about the bus route and operation are also considered. A Reinforcement Learning Genetic Algorithm is developed to solve the proposed model. Two case studies including the classic Mandl's road network and a large road network in the context of Zhengzhou city are conducted to demonstrate the effectiveness of the proposed model and the solution algorithm. Results suggest that the proposed methodology is helpful for improving the travel reliability of the transit network with minimal cost increase.
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| 6. |
- Tong, Pei, et al.
(author)
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Speed planning for connected electric buses based on battery capacity loss
- 2021
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In: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526. ; 321
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Journal article (peer-reviewed)abstract
- Connected battery electric buses (CBEBs) equipped with Vehicle-to-Infrastructure (V2I) have great potential for improving bus performance, through aspects such as energy saving and travel time reduction. For CBEBs, intelligent speed planning determines the energy consumption, which directly affects the charging or discharging of current to the battery and furthermore affects the battery degradation. This paper develops a speed planning model, aiming to minimize the total battery capacity loss of a battery electric bus by optimizing the bus speed of driving intervals and avoiding stopping delays at intersections along a bus line with a bus lane. Motor modeling, battery modeling, bus operation modeling, and constraints such as cruise time, arrival time, travel speed, acceleration and deceleration are all involved. A Q-Learning-based solution algorithm is proposed to solve the developed model. A case study based on a specific bus line with a bus lane is conducted. Results indicate that the developed method has an obvious advantage in reducing the total battery capacity loss compared with the greedy policy strategy. This study provides potential for future CBEB operation design.
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| 7. |
- Xu, Mingtao, et al.
(author)
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Multi-Agent Fuzzy-Based Transit Signal Priority Control for Traffic Network Considering Conflicting Priority Requests
- 2022
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In: IEEE Transactions on Intelligent Transportation Systems. - 1524-9050 .- 1558-0016. ; 23:2, s. 1554-1564
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Journal article (peer-reviewed)abstract
- The performance of transit signal priority (TSP) with conflicting priority requests highly depends on the serving sequence of multiple TSP requests. A series of existing methods have been developed to determine the priority level of requests. However, most of these methods focused on isolated intersections or a small number of intersections, which are not applicable to complex, dynamic and nonlinear urban traffic networks. In this regard, we propose a multi-agent TSP control method at the network level considering conflicting priority requests. Fuzzy inference is used to manage signal control. We further develop a specific control algorithm. The performance of the proposed method is verified by a case study with a sizeable traffic network with 20 intersections and 49 links. Simulation results demonstrate that the proposed method outperforms other three benchmarking methods under different traffic demands and bus departure frequencies. It is worth-noting that the improvement becomes more notable with the increase of traffic demands and the reduction of bus departure frequencies.
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| 8. |
- Yan, Yadan, et al.
(author)
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On the design and operational performance of waiting areas in at-grade signalized intersections: an overview
- 2018
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In: Transportmetrica A: Transport Science. - : Informa UK Limited. - 2324-9943 .- 2324-9935. ; 14:10, s. 901-928
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Journal article (peer-reviewed)abstract
- In the past two decades, the waiting area has been widely used in many large cities in China as an effective strategy to increase the capacity of at-grade signalized intersections, especially during peak hours. Unfortunately, despite its popularity and prevalence, there does not exist any quantitative technical/design standards for formulating the implementation of waiting area and evaluating its performance. It is an unconventional design from practice and its theoretical investigation is actually after it is implemented in numerous signalized intersections. In this regard, this paper presents an overview of existing research and applications with a focus on the traffic operations and performance evaluation of the waiting area in at-grade signalized intersections. We first emphasize the design and its integration with signal phasing. Then performance analysis is introduced. This is followed by a few critical remarks and directions of the future work.
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| 9. |
- Zhang, Jin, et al.
(author)
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A Comparative Study of Weather Effects on Black Spot Identification for Motorways and Urban Arterials Roads
- 2018
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In: CICTP 2018: Intelligence, Connectivity, and Mobility - Proceedings of the 18th COTA International Conference of Transportation Professionals. - Reston, VA : American Society of Civil Engineers. ; , s. 1827-1836
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Conference paper (peer-reviewed)abstract
- It is well acknowledged that the seasonality (dry or rainy seasons) has significant impacts on crashes. Being able to differentiate the crashes that occur because of poor surface conditions (i.e., when the road is wet) is important for the economical use of available resources, as these segments of roads may only require signage and/or resurfacing. However, this effect is always ignored in the traditional black spot identification (BSID) techniques. This paper proposes an improved BSID model by taking into account the wet/dry crash rate ratio. Comparative study based on a high-speed motorway and a relatively low-speed urban arterials road is carried out. Results indicate that the proposed model has good applicability. The impact of rainfall has been minimized on the results of a BSID analysis.
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| 10. |
- Zhang, Jian, 1994, et al.
(author)
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Eco-driving control for connected and automated electric vehicles at signalized intersections with wireless charging
- 2021
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In: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 282
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Journal article (peer-reviewed)abstract
- Electric vehicles have been well recognized by many as a solution to reduce greenhouse emissions, improve mobility, and decrease energy consumption in the transportation system. In this paper, we propose a novel wireless charging scheme for electric vehicles. The proposed scheme deploys partial wireless charging lane to intersections, so as to utilize the slow movement of vehicles at traffic lights for recharging. Furthermore, an eco-driving control strategy for electric vehicles at intersections with wireless charging, i.e., W-eco-driving, is developed, aiming to decrease the total energy consumption and increase traffic efficiency. With the aid of connected and automated vehicles technology, driving and surrounding data are accessible in real-time. Then electric vehicles can be controlled using the W-eco-driving strategy accurately. The proposed strategy is finally validated based on a specific intersection configuration. Both single electric vehicle control and electric vehicle platooning are discussed in test examples. We also investigate the influences of wireless charging power, location and length. Numerical results show that the wireless charging scheme with W-eco-driving is able to increase the driving range and decrease the travel cost simultaneously. The total travel cost can be saved up to 16% by following W-eco-driving. We further provide some suggestions about the construction of wireless charging lanes in the vicinity of signalized intersections. Compared with the pursuit of a long wireless charging lane, it is more important to put it in a proper position in the early stage of construction.
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