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Two drifting paths of Sargassum bloom in the Yellow Sea and East China Sea during 2019-2020

Acta Oceanologica Sinica 2022年第6期41卷 78-87页

作者： Chao Yuan Jie Xiao Xuelei Zhang Mingzhu Fu Zongling Wang The MNR Key Laboratory of Marine Eco-Environmental Science and Technology First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China Laboratory of Marine Ecology and Environmental Science Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China National Engineering Laboratory for Integrated Aero-Space-Ground-Ocean Big Data Application Technology Xi'an 710129China

The macroalgal blooms of floating brown algae Sargassum horneri are increasing in the Yellow Sea and East China Sea during the past few ***,the annual pattern of Sargassum bloom is not well *** study the developing pattern and explore the impacts from hydro-meteorologic environment,high resolution satellite imageries were used to monitor the distribution,coverage and drifting of the pelagic Sargassum rafts in the Yellow Sea and East China Sea from September 2019 to August *** blooms were detected from October 2019 to June 2020 and presented two successive drifting paths that both initiated from around 37°*** first path spanned smaller spatial scale and shorter period,starting with a bloom of 3 km^(2) distribution area near the eastern tip of Shandong Peninsula in late October 2019 and drifted southwards,hit the Pyropia aquaculture area in early January 2020,then vanished in the northwest of East China Sea(ca.32°N)around end of *** second path began with a large distribution area of 23000 km^(2) east of 123°E in late January 2020,firstly moved southwards in the central Yellow Sea and northern East China Sea(north of 29°N)till late April,then turned northwards with monsoon wind and vanished from late June to *** mean sea surface temperature of 8℃ to 20℃ in the Sargassum bloom areas corresponded to in situ observed temperature range for vegetative growth and floating of *** was no observed floating Sargassum blooms during July through September in the Yellow Sea and East China *** results indicate that floating *** is unable to complete life cycle in the Yellow Sea and East China Sea,and provide insights to the future management of Sargassum *** studies are needed to validate the pattern and source of annual Sargassum bloom in the Yellow Sea and East China Sea.

关键词： Sargassum horneri macroalgal bloom high resolution remote sensing wind directions sea surface temperature Yellow Sea and East China Sea

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A Structure-Aware Lane Graph Transformer Model for Vehicle Trajectory Prediction

arXiv

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arXiv 2024年

作者： Sun, Zhanbo Dong, Caiyin Ji, Ang Zhao, Ruibin Zhao, Yu The School of Transportation and Logistics The National Engineering Laboratory of Integrated Transportation Big Data Application Technology Southwest Jiaotong University Chengdu China Zelos Intelligent Technology Limited Company Jiangsu Suzhou China

Accurate prediction of future trajectories for surrounding vehicles is vital for the safe operation of autonomous vehicles. This study proposes a Lane Graph Transformer (LGT) model with structure-aware capabilities. Its key contribution lies in encoding the map topology structure into the attention mechanism. To address variations in lane information from different directions, four Relative Positional Encoding (RPE) matrices are introduced to capture the local details of the map topology structure. Additionally, two Shortest Path Distance (SPD) matrices are employed to capture distance information between two accessible lanes. Numerical results indicate that the proposed LGT model achieves a significantly higher prediction performance on the Argoverse 2 dataset. Specifically, the minFDE6 metric was decreased by 60.73% compared to the Argoverse 2 baseline model (Nearest Neighbor) and the b-minFDE6 metric was reduced by 2.65% compared to the baseline LaneGCN model. Furthermore, ablation experiments demonstrated that the consideration of map topology structure led to a 4.24% drop in the b-minFDE6 metric, validating the effectiveness of this model. Copyright © 2024, The Authors. All rights reserved.

关键词： Autonomous vehicles

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Unveiling the planar deformation mechanisms for improved formability in pre-twinned AZ31 Mg alloy sheet at warm temperature

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Journal of Magnesium and Alloys 2023年第12期11卷 4659-4678页

作者： Xiaohuan Pan Lifei Wang Pengbin Lu Hua Zhang Guangsheng Huang Liuwei Zheng Bin Xing Weili Cheng Hongxia Wang Wei Liang Kwang Seon Shin Shanxi Key Laboratory of Advanced Magnesium-Based Materials College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan 030024China National Engineering Laboratory for Industrial Big-data Application Technology Chongqing Innovation Center of Industrial Big-Data Co.Ltd.Chongqing 400707China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Institute for Advanced Studies in Precision Materials Yantai UniversityYantai 264005China National Engineering Research Center for Magnesium Alloys College of Materials Science&EngineeringChongqing UniversityChongqing 400044China Magnesium Technology Innovation Center School of Materials Science and EngineeringSeoul National University1 Gwanak-roGwanak-guSeoul 08826South Korea

To investigate the role of pre-twins in Mg alloy sheets during warm planar deformation,the stretch forming is conducted at 200℃.Results suggest the formability of the pre-twinned AZ31 Mg alloy sheet is enhanced to 11.30 *** mechanisms for the improved formability and the deformation behaviors during the planar stretch forming are systematically investigated based on the planar stress *** Schmid factor for deformation mechanisms are calculated,the results reveal that planar stress states extremely affect the Schmid factor for{10-12}*** detwinning is activated and the prismatic slip is enhanced in the pre-twinned sheet,especially under the planar extension stress state in the outer ***,the thickness-direction strain is accommodated *** dynamic recrystallization(DRX)type is continuous DRX(CDRX)regardless of the planar stress ***,the CDRX degree is greater under the planar extension stress *** twin lattices deviate from the perfect{10-12}twinning relation due to the planar compression stress state and the *** basal texture is weakened when the planar stress state tends to change the texture components.

关键词： AZ31 Mg alloy sheet Planar stretch forming Planar stress states Continuous dynamic recrystallization {10-12}tensile twinning

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A Study of High-Speed Railway Train Merger and Adjustment Based on Regional Network 5th

A Study of High-Speed Railway Train Merger and Adjustment Ba...

引用

5th International Conference on Smart Vehicular technology, transportation, Communication and applications, VTCA 2022

作者： Shi, Fangyu Wu, Zhi Tan, Haowen Yang, Min Pan, Jinshan School of Transportation and Logistics Southwest Jiaotong University Sichuan Chengdu610031 China National and Local Joint Engineering Laboratory of Comprehensive Intelligent Transportation Southwest Jiaotong University Chengdu610031 China National Engineering Laboratory of Integrated Transportation Big Data Application Technology Sichuan Chengdu610031 China China Railway Chengdu Railway Group Co. Ltd. Sichuan Chengdu610000 China School of Transportation Engineering Chang’an University Shanxi Xi’an710000 China

ISBN: (纸本)9789819908479

Based on the "road network-region-cluster" three-level network, the optimization problem of train operation scheme under network condition is transformed into the problem of direct train operation and train combination between regions on cluster network. The design of train operation scheme based on the railway network realizes the passenger flow transportation within the regional network. However, the cross-network passenger flow on the regional network still needs to transfer at the overlapping nodes. In this paper, the train merging adjustment is carried out on the overlapping nodes identified by the regional network division, and the principle of train merging is studied. The train merging adjustment model is designed with the goal of the highest direct passenger flow, the largest train operation benefit and the lowest passenger travel cost, and the genetic algorithm is designed to solve the model. Finally, taking the high-speed rail network in Chengdu Bureau as an example, the feasibility and rationality of the model and algorithm proposed in this paper are verified. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Merging

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Cooperative Merging for Connected Automated Vehicles in Mixed Traffic: A Multi-Agent Reinforcement Learning Approach

SSRN

引用

SSRN 2023年

作者： Sun, Zhanbo Huang, Jiayi Ji, Ang Zhao, Ruibin Zheng, Guoqian School of Transportation and Logistics Southwest Jiaotong University Chengdu China National Engineering Laboratory of Integrated Transportation Big Data Application Technology Chengdu China

The paper investigates the cooperative decision-making for mixed traffic (CDMMT) ramp merging problem based on a multi-agent reinforcement learning (MARL) approach. With the help of V2X technology, autonomous agents exchange information and corresponding strategies throughout the learning procedure, which can align individual interests with the system’s efficiency. To further improve the driving performance of autonomous agents, expert demonstrations for car-following and merging actions are exploited to diminish collisions at the beginning of the training process, the Multi-Agent Proximal Policy Optimization (MAPPO) with a curriculum learning process is then designed to learn strategies from scenarios with various flow conditions and achieve fast and stable convergence. The simulation results indicate that, compared to human-driven vehicles behaving in over-competitive or conservative strategies, MARL-based agents can improve traffic efficiency by 57.9% in a fully saturated situation. In addition, it is found that, even with 10% CAV penetration, the overall traffic efficiency can be improved by 11.8%. Furthermore, as the mainline traffic flow increases, mainline vehicles prioritize efficiency over safety. In contrast, ramp vehicles exhibit a more conservative behavior, emphasizing safety in response to crowded mainline traffic. Finally, the simulation experiments with different demand splits, penetration rates, and traffic densities reveal the model’s potential learning and transferring capabilities in dynamic traffic conditions, which can hopefully offer valuable insights for future research related to CDMMT problems. © 2023, The Authors. All rights reserved.

关键词： Reinforcement learning

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RANSACs for 3D Rigid Registration:A Comparative Evaluation

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IEEE/CAA Journal of Automatica Sinica 2022年第10期9卷 1861-1878页

作者： Jiaqi Yang Zhiqiang Huang Siwen Quan Zhiguo Cao Yanning Zhang the National Engineering Laboratory for Integrated Aero-Space-Ground-Ocean Big Data Application Technology School of Computer ScienceNorthwestern Polytechnical UniversityXi’an 710072China the School of Electronic and Control Engineering Chang’an UniversityXi’an 710064China the School of Artificial Intelligence and Automation Huazhong University of Science and TechnologyWuhan 430074China IEEE

Estimating an accurate six-degree-of-freedom(6-Do F)pose from correspondences with outliers remains a critical issue to 3D rigid *** sample consensus(RANSAC)and its variants are popular solutions to this *** there have been a number of RANSAC-fashion estimators,two issues remain ***,it is unclear which estimator is more appropriate to a particular ***,the impacts of different sampling strategies,hypothesis generation methods,hypothesis evaluation metrics,and stop criteria on the overall estimators remain *** work fills these gaps by first considering six existing RANSAC-fashion methods and then proposing eight variants for a comprehensive *** objective is to thoroughly compare estimators in the RANSAC family,and evaluate the effects of each key stage on the eventual 6-Do F pose estimation *** have been carried out on four standard datasets with different application scenarios,data modalities,and *** provide us with input correspondence sets with a variety of inlier ratios,spatial distributions,and *** on the experimental results,we summarize remarkable outcomes and valuable findings,so as to give practical instructions to real-world applications,and highlight current bottlenecks and potential solutions in this research realm.

关键词： 3D rigid registration performance evaluation point cloud pose estimation

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Predicting the transportation Activities of Construction Waste Hauling Trucks: An Input-Output Hidden Markov Approach

arXiv

引用

arXiv 2023年

作者： Yang, Hongtai Lei, Boyi Han, Ke Liu, Luna School of Transportation and Logistics National Engineering Laboratory of Integrated Transportation Big Data Application Technology National United Engineering Laboratory of Integrated and Intelligent Transportation Institute of System Science and Engineering Southwest Jiaotong University Chengdu611756 China

Construction waste hauling trucks (CWHTs), as one of the most commonly seen heavy-duty vehicles in major cities around the globe, are usually subject to a series of regulations and spatial-temporal access restrictions because they not only produce significant NOx and PM emissions but also causes on-road fugitive dust. The timely and accurate prediction of CWHTs’ destinations and dwell times play a key role in effective environmental management. To address this challenge, we propose a prediction method based on an interpretable activity-based model, input-output hidden Markov model (IOHMM), and validate it on 300 CWHTs in Chengdu, China. Contextual factors are considered in the model to improve its prediction power. Results show that the IOHMM outperforms several baseline models, including Markov chains, linear regression, and long short-term memory. Factors influencing the predictability of CWHTs’ transportation activities are also explored using linear regression models. Results suggest the proposed model holds promise in assisting authorities by predicting the upcoming transportation activities of CWHTs and administering intervention in a timely and effective manner. Copyright © 2023, The Authors. All rights reserved.

关键词： Trucks

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HyperCalm Sketch: One-Pass Mining Periodic Batches in data Streams 39

HyperCalm Sketch: One-Pass Mining Periodic Batches in Data S...

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39th IEEE International Conference on data engineering, ICDE 2023

作者： Liu, Zirui Kong, Chaozhe Yang, Kaicheng Yang, Tong Miao, Ruijie Chen, Qizhi Zhao, Yikai Tu, Yaofeng Cui, Bin Peking University School of Computer Science National Engineering Laboratory for Big Data Analysis Technology and Application Beijing China Peng Cheng Laboratory Shenzhen China Zte Corporation China

ISBN: (纸本)9798350322279

Batch is an important pattern in data streams, which refers to a group of identical items that arrive closely. We find that some special batches that arrive periodically are of great value. In this paper, we formally define a new pattern, namely periodic batches. A group of periodic batches refers to several batches of the same item, where these batches arrive periodically. Studying periodic batches is important in many applications, such as caches, financial markets, online advertisements, networks, etc. We propose a one-pass sketching algorithm, namely the HyperCalm sketch, which takes two phases to detect periodic batches in real time. In phase 1, we propose a time-aware Bloom filter, namely HyperBloomFilter (HyperBF), to detect the start of batches. In phase 2, we propose an enhanced top-k algorithm, called Calm Space-Saving (CalmSS), to report top-k periodic batches. We theoretically derive the error bounds for HyperBF and CalmSS. Extensive experiments show HyperCalm outperforms the strawman solutions 4× in term of average relative error and 13.2× in term of speed. We also apply HyperCalm to a cache system and integrate HyperCalm into Apache Flink. All related codes are open-sourced. © 2023 IEEE.

关键词： Error analysis

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An improved cellular automata model of traffic flow with look-ahead potential

An improved cellular automata model of traffic flow with loo...

引用

2021 China Automation Congress, CAC 2021

作者： Ma, Xiao Liu, Yu-Hu School of Mathematics Southwest Jiaotong University National Engineering Laboratory of Integrated Transportation Big Data Application Technology Chengdu China

ISBN: (纸本)9781665426473

This paper presents an improved automata model for traffic flow based upon models for cellular automata and traffic flow. The proposed model is concerned with the headway and multiple velocities. The proposed model enforces the stochastic rules for moving a car on the basis of traffic in front of it. Rules for updating the velocity of car relies upon the location of the car as well as front traffic and their velocities. In particular, by using numerical simulations, the model proposed in this study can reach the steady-state more quickly for random perturbations. © 2021 IEEE

关键词： Cellular automata

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Optimal Scheduling of Single-Line Electric Buses with Battery Swapping

Optimal Scheduling of Single-Line Electric Buses with Batter...

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IEEE International Conference on Intelligent transportation engineering (ICITE)

作者： Yuyan Guo Tao Liu National Engineering Laboratory of Integrated Transportation Big Data Application Technology Institute of System Science and Engineering School of Transportation and Logistics Southwest Jiaotong University Chengdu China

ISBN: (数字)9798350314212

ISBN: (纸本)9798350314229

With the advantages of zero emission and comfortable riding experience, battery-electric buses (BEBs) are widely adopted in public transit agencies as a green alternative to conventional diesel buses. Battery swapping technology is an efficient and promising charging technology to address the issues of battery range anxiety and long battery charging time. This study developed a two-stage optimization model to optimize the single-line battery-electric bus scheduling problem considering battery swapping. At the first stage, a bi-objective integer programming model is established to determine the minimum BEB fleet size, together with the BEB-to-trip assignment and battery swapping schedule. At the second stage, an integer linear programming model is formulated to determine the required minimum number of batteries. An $\epsilon$ -constraint method is designed to investigate the trade-off between the required minimum fleet size and the number of back-up batteries. Finally, a real-world case study of a BEB line in Chengdu, China, is conducted to demonstrate the effectiveness of the optimization model and solution method. Sensitivity analyses are further conducted to understand the impacts of some key parameters, including battery capacity, number of trips, cycle time, and battery swapping time. The results show that battery capacity and cycle time have significant influences on BEB-to-trip assignment results and battery swapping schedule.

关键词： Integer programming Schedules Sensitivity analysis Optimization models transportation Stochastic processes Optimal scheduling Integer linear programming Scheduling Batteries

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