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RMGen : a tri-layer vehicular trajectory data generation model exploring urban region division and mobility pattern

- Kong, Xiangjie, Chen, Qiao, Hou, Mingliang, Rahim, Azizur, Ma, Kai, Xia, Feng

  • Authors: Kong, Xiangjie , Chen, Qiao , Hou, Mingliang , Rahim, Azizur , Ma, Kai , Xia, Feng
  • Date: 2022
  • Type: Text , Journal article
  • Relation: IEEE Transactions on Vehicular Technology Vol. 71, no. 9 (2022), p. 9225-9238
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  • Description: As an important branch of the Internet of Things (IoT), the Internet of Vehicles (IoV) has attracted extensive attention in the research field. To deeply study the IoV and build a vehicle spatiotemporal interaction network, it is necessary to use the trajectory data of private cars. However, due to privacy and security protection policies and other reasons, the data set of private cars cannot be obtained, which hinders the research on the social attributes of vehicles in the IoV. Most of the previous work generated the same type of data, and how to generate private car data sets from various existing data sets is a huge challenge. In this paper, we propose a tri-layer framework to solve this problem. First, we propose a novel region division scheme that considers detailed inter-region relations connected by traffic flux. Second, a new spatial-temporal interaction model is developed to estimate the traffic flow between two regions. Third, we devise an evaluation pipeline to validate generation results from microscopic and macroscopic perspectives. Qualitative and quantitative results demonstrate that the data generated in heavy density scenarios can provide strong data support for downstream IoV and mobility research tasks. © 1967-2012 IEEE.

Enhanced on-off keying modulation for wireless power transfer systems to improve efficiency over a wide load range

- Li, Yong, Cui, Xueyan, Chen, Junwen, Liu, Yeran, Liu, Shunpan, Hu, Jiefeng, He, Zhengyou

  • Authors: Li, Yong , Cui, Xueyan , Chen, Junwen , Liu, Yeran , Liu, Shunpan , Hu, Jiefeng , He, Zhengyou
  • Date: 2024
  • Type: Text , Journal article
  • Relation: IEEE Transactions on Vehicular Technology Vol. 73, no. 5 (2024), p. 6409-6419
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  • Description: Maximum efficiency point tracking (MEPT) is a key concept to improve the ac-ac efficiency of the wireless power transfer (WPT) systems by controlling the equivalent load impedance with a dc-dc converter or an active rectifier. The on-off keying (OOK) modulation can reduce the switching losses of the converters to achieve MEPT but generates relatively large dc voltage ripples. In order to solve this problem, this article proposes an enhanced on-off keying (EOOK) modulation method by adding a half-bridge mode based on OOK modulation for WPT systems. By combining the three operation modes, both the inverter and the active rectifier can operate in full-bridge-half-bridge mode or half-bridge-zero mode to adapt to different power levels and achieve MEPT simultaneously. Meanwhile, the ZVS condition and the low voltage ripple are achieved as well. The circuit model of the proposed method is analyzed to derive the equivalent load resistance, the output voltage gain, and the output power with respect to the modulation of EOOK. The reason for output voltage ripples and the power losses on both the transmitting and receiving sides are also revealed. An experimental prototype is built to verify the effectiveness of the proposed method. The experimental results show that the proposed method can maintain constant voltage output and achieve MEPT as well as ZVS operation, with high efficiency of up to 94.761% over a wide range of load conditions. © 1967-2012 IEEE.
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