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Analyzing distributions for travel time data collected using radiofrequency identification technique in urban road networks

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Science China(Technological Sciences) 2019年第1期62卷 106-120页

作者： GUO JianHua LI ChangGuang QIN Xiao HUANG Wei WEI Yun CAO JinDe intelligent Transportation system research center Southeast University Transportation Sensing and Cognition research center Southeast University Department of Civil & Environmental Engineering University of Wisconsin at Milwaukee National Engineering Laboratory for Green and Safe Construction Technology in Urban Rail Transit School of Mathematics Southeast University

Travel time distribution studies are fundamental for supporting transportation system reliability studies, particularly for urban road networks. However, such studies are generally based on travel time data sets with limited sample sizes, which provide inconsistent findings. In this paper, a large amount of travel time data collected from the emerging radio frequency identification(RFID) technique are used to conduct empirical investigations and estimations of travel time distributions, and three major findings are determined. First, travel time data are shown to have a complex statistical structure: the travel time distribution is in general peaky, multi-modal, and skewed to the right, which cross validates findings shown in previous publications. Second, unimodal distribution models are shown to be unable to capture the complex statistical dynamics embedded in the travel time data; therefore,a multistate distribution model is more appropriate for modeling travel time distributions. In this respect, a three-component gaussian mixture model(GMM) is tested and results consistently outperform those of unimodal distribution models. Finally, the aggregation time interval is shown to have a trivial effect on the shape of travel time distributions: the travel time distribution is stable under different aggregation time intervals. Future work is recommended to investigate further travel time variabilities and travel time distribution estimations.

关键词： reliability travel time travel time distribution time interval RFID

Decision Analysis on IoV Routing Transmission and Energy Efficiency Optimization Algorithm with AmBC

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Computer Modeling in Engineering & Sciences 2023年第12期137卷 2661-2673页

作者： Baofeng Ji Mingkun Zhang Weixing Wang Song Chen Henan University of Science and Technology College of Information EngineeringLuoyang471000China Longmen Laboratory Research and Innovation Center of Intelligent SystemLuoyang471000China Institute of Atmospheric Physics Chinese Academy of Sciences(LAGEO)Beijing100000China YTO Group Corporation Luoyang471000China

The improvement of the quality and efficiency of vehicle wireless network data transmission is always a key concern in the Internet of Vehicles(IoV).Routing transmission solved the limitation of transmission distance to a certain *** routing algorithm cannot adapt to complex traffic environment,resulting in low transmission *** order to improve the transmission success rate and quality of vehicle network routing transmission,make the routing algorithm more suitable for complex traffic environment,and reduce transmission power consumption to improve energy efficiency,a comprehensive optimized routing transmission algorithm is *** on the routing transmission algorithm,an optimization algorithmbased on road condition,vehicle status and network performance is proposed to improve the success rate of routing transmission in the *** distance difference and density are used as decision-making indicators to measure Road Side Unit(RSU)assisted *** the Ambient backscatter communication(AmBC)technology and energy collection are used to reduce the energy consumption of routing relay *** energy collection optimization algorithm is proposed to optimize the energy efficiency of AmBC and improve the energy efficiency of *** results show that the proposed routing optimization algorithm can effectively improve the success rate of packet transmission in vehicular ad hoc networks(VANETs),and theAmBC optimization algorithmcan effectively reduce energy consumption in the transmission *** proposed optimization algorithm achieves comprehensive optimization of routing transmission performance and energy efficiency.

关键词： IoV routing algorithm AmBC relay transmission

Reflectionless spatial beam benders with arbitrary bending angle by introducing optic-null medium into transformation optics

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Chinese Physics B 2021年第3期30卷 242-247页

作者： Fei Sun Yi-Chao Liu Yi-Biao Yang Hong-Ming Fei Zhi-Hui Chen Sai-Ling He Key Laboratory of Advanced Transducers and intelligent Control system Ministry of Education and Shanxi ProvinceCollege of Physics and OptoelectronicsTaiyuan University of TechnologyTaiyuan 030024China National Engineering research center for Optical Instruments Center for Optical and Electromagnetic ResearchZhejiang UniversityHangzhou 310058China

By introducing an optic-null medium into the finite embedded transformation,a reflectionless spatial beam bender is designed,which can steer the output beam by a fixed pre-designed angleβfor an arbitrary incident *** bending angleβof the beam bender is determined by the geometrical angle of the device,which can be changed by simply choosing different geometrical *** various bending angles,the designed spatial beam bender can be realized by the same materials(i.e.,an optic-null medium),which is a homogenous anisotropic *** simulations verify the reflectionless bending effect and rotated imaging ability of the proposed beam bender.A reduction model of the optic-null medium is studied,which can also be used for a reflectionless spatial beam bender with a pre-designed bending angle.

关键词： spatial beam benders optic-null medium transformation optics

Quantifying the Contribution of Track Changes to Interannual Variations of North Atlantic Intense Hurricanes

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Advances in Atmospheric Sciences 2022年第2期39卷 260-271页

作者： Jun LU Liguang WU Shunwu ZHOU Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Joint Center for Data Assimilation Research and ApplicationsNanjing University of Information Science and TechnologyNanjing 210031China Department of Atmospheric and Oceanic Sciences and Institute of Atmospheric Sciences Fudan UniversityShanghai 200433China innovation center of Ocean and Atmosphere system Zhuhai Fudan Innovation Research InstituteZhuhai 518057China

Previous studies have linked interannual variability of tropical cyclone(TC)intensity in the North Atlantic basin(NA)to Sahelian rainfall,vertical shear of the environmental flow,and relative sea surface temperature(SST).In this study,the contribution of TC track changes to the interannual variations of intense hurricane activity in the North Atlantic basin is evaluated through numerical *** is found that that observed interannual variations of the frequency of intense hurricanes during the period 1958–2017 are dynamically consistent with changes in the large-scale ocean/atmosphere *** changes can account for~50%of the interannual variability of intense hurricanes,while no significant difference is found for individual environmental parameters between active and inactive *** only significant difference between active and inactive years is in the duration of TC intensification in the region east of 60°*** duration increase is not due to the slow-down of TC *** active years,a southeastward shift of the formation location in the region east of 60°W causes TCs to take a westward prevailing track,which allows TCs to have a longer opportunity for *** the other hand,most TCs in inactive years take a recurving track,leading to a shorter duration of *** study suggests that the influence of track changes should be considered to understand the basin-wide intensity changes in the North Atlantic basin on the interannual time scale.

关键词： interannual variations intense hurricanes track changes vertical shear

Semantics-aware transformer for 3D reconstruction from binocular images

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Optoelectronics Letters 2022年第5期18卷 293-299页

作者： JIA Xin YANG Shourui GUAN Diyi the engineering research center of learning-based intelligent system and the key laboratoryof computer vision and system of ministry of education tianjin university of technologytianjin 300384china zhejiang university of technology hangzhou 310014china

Existing multi-view three-dimensional(3 D) reconstruction methods can only capture single type of feature from input view, failing to obtain fine-grained semantics for reconstructing the complex shapes. They rarely explore the semantic association between input views, leading to a rough 3 D shape. To address these challenges, we propose a semantics-aware transformer(SATF) for 3 D reconstruction. It is composed of two parallel view transformer encoders and a point cloud transformer decoder, and takes two red, green and blue(RGB) images as input and outputs a dense point cloud with richer details. Each view transformer encoder can learn a multi-level feature, facilitating characterizing fine-grained semantics from input view. The point cloud transformer decoder explores a semantically-associated feature by aligning the semantics of two input views, which describes the semantic association between views. Furthermore, it can generate a sparse point cloud using the semantically-associated feature. At last, the decoder enriches the sparse point cloud for producing a dense point cloud with richer details. Extensive experiments on the Shape Net dataset show that our SATF outperforms the state-of-the-art methods.

关键词： details semantic decoder

Roll-to-roll printing trench-like metasurface film for radiative cooling

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Light(Science & Applications) 2023年第12期12卷 2538-2539页

作者： Yaoguang Ma State Key Laboratory of Extreme Photonics and Instrumentation College of Optical Science and EngineeringInternational ResearchCenter for Advanced PhotonicsZhejiang UniversityHangzhou 310027China ZJU-Hangzhou Global Scientific and Technological innovation center Hangzhou 311215China Jiaxing Key Laboratory of Photonic Sensing&intelligent Imaging Intelligent Optics&Photonics Research CenterJiaxing Research InstituteZhejiang UniversityJiaxing 314000China

A Roll-to-roll technology can enable the fabrication of trench-like photonic meta-structures that are strongly absorptive in the MIR region,providing a controllable optical response for diurnal radiative cooling.

关键词： trench radiative printing

An iterative linear quadratic regulator based trajectory tracking controller for wheeled mobile robot

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第8期13卷 593-600页

作者： Hao-jie ZHANG Jian-wei GONG Yan JIANG Guang-ming XIONG Hui-yan CHEN intelligent Vehicle research center Beijing Institute of TechnologyBeijing 100081China

We present an iterative linear quadratic regulator(ILQR) method for trajectory tracking control of a wheeled mobile robot *** proposed scheme involves a kinematic model linearization technique,a global trajectory generation algorithm,and trajectory tracking controller design.A lattice planner,which searches over a 3D(x,y,θ) configuration space,is adopted to generate the global *** ILQR method is used to design a local trajectory tracking *** effectiveness of the proposed method is demonstrated in simulation and experiment with a significantly asymmetric differential drive *** performance of the local controller is analyzed and compared with that of the existing linear quadratic regulator(LQR) *** to the experiments,the new controller improves the control sequences(v,ω) iteratively and produces slightly better ***,two trajectories,'S' and '8' courses,are followed with sufficient accuracy using the proposed controller.

关键词： Lattice planner Global trajectory Kinematic model Trajectory tracking controller Iterative linear quadratic regulator (ILQR)

Noninvasive Human-Prosthesis Interfaces for Locomotion Intent Recognition:A Review

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Cyborg and Bionic systems 2021年第1期2021卷 192-205页

作者： Dongfang Xu Qining Wang Robotics research Group College of EngineeringPeking UniversityChina Beijing Engineering research center of intelligent Rehabilitation Engineering China The Beijing innovation center for Engineering Science and Advanced Technology(BIC-ESAT) Peking UniversityChina

The lower-limb robotic prostheses can provide assistance for amputees’daily activities by restoring the biomechanical functions of missing limb(s).To set proper control strategies and develop the corresponding controller for robotic prosthesis,a prosthesis user’s intent must be acquired in time,which is still a major challenge and has attracted intensive *** work focuses on the robotic prosthesis user’s locomotion intent recognition based on the noninvasive sensing methods from the recognition task perspective(locomotion mode recognition,gait event detection,and continuous gait phase estimation)and reviews the state-ofthe-art intent recognition techniques in a lower-limb prosthesis *** current research status,including recognition approach,progress,challenges,and future prospects in the human’s intent recognition,has been *** particular for the recognition approach,the paper analyzes the recent studies and discusses the role of each element in locomotion intent *** work summarizes the existing research results and problems and contributes a general framework for the intent recognition based on lower-limb prosthesis.

关键词： Intent recognition motion

A heuristic control framework for heavy-duty hexapod robot over complex terrain

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IET Cyber-systems and Robotics 2022年第4期4卷 322-330页

作者： Jinmian Hou Hui Chai Yibin Li Yaxian Xin Wei Chen School of Control Science and Engineering Shandong UniversityJinanChina Engineering research center of intelligent Unmanned system Ministry of EducationShandong UniversityJinanChina

The large and heavy-duty hexapod robot has strong motion stability and load capacity,which promises to have a wide range of application prospects in rescue and disaster ***-mode gait and static stability during walking make the hexapod robot adapt to more diverse terrains,while little research has been conducted on the motion control methods of heavy-duty hexapod robots in complex environments.A novel heuristic whole-body motion control framework for the heavy-duty hexapod robot to traverse complex terrain is *** splitting the legged locomotion into a single task,the whole-body motion could be planned in a reasonable *** terrain adaptation strategy is designed to improve the complex terrain *** reaction forces are then optimised based on single rigid-body dynamics with *** framework utilised simple but powerful heuristics to approximate complex dynamics and allows for a single set of parameters for all task *** results demonstrate the robustness and adaptability of the proposed framework.

关键词： legged locomotion robotics robots