Search

Your search keyword '"Wang, Qingfeng"' showing total 135 results
Start Over Author "Wang, Qingfeng" Publisher ieee
135 results on '"Wang, Qingfeng"'

20. Study on Transient Overvoltage During Pantograph Lifting and Lowering of Intercity Train

Author

Feng Qingpeng, Liu Yining, Wang Qingfeng, Zhang Yitao, Liang Jianying, Zhang Jianqiong, and Lin Yuwen

Subjects
Computer science, Overvoltage, Rail transit, Pantograph, Waveform, Transient (oscillation), Line (electrical engineering), Automotive engineering, Short distance, Voltage
Abstract

Intercity train is a short distance train used for transportation between city and surrounding areas. Compared with other types of EMUs, it has higher pantograph lifting frequency. In this paper, based on Simulink platform, the transient overvoltage generated in the process of intercity train pantograph lifting is simulated, and the voltage waveform in the process of intercity train pantograph lifting is measured at Tongling station of Wenzhou rail transit line S1, which verifies the accuracy of the simulation results.

Published
2021

23. A Compact Dual-Wideband Magnetoelectric Dipole Antenna for 5G Millimeter-Wave Applications.

Author

Ni, Shucheng, Li, Xiangqiang, Qiao, Xiaobin, Wang, Qingfeng, and Zhang, Jianqiong

Subjects
ANTENNA feeds, DIPOLE antennas, ANTENNAS (Electronics), 5G networks, MAGNETIC dipoles, ANTENNA design
Abstract

A compact dual-wideband millimeter-wave magnetoelectric (ME) dipole antenna based on dual-mode operation is proposed in this article. The ME dipole consists of two mirrored U-shaped patches, a substrate integrated waveguide (SIW) cavity with slotted top and two metallized vias connecting the patches to the slot. The two mirrored U-shaped patches work as an electric dipole (E-dipole), while the slot on the top of the SIW cavity and two metallized vias works as a magnetic dipole (M-dipole). In the lower frequency band, $0.5\lambda $ modes of the E-dipole and the M-dipole are excited to form the $0.5\lambda $ mode of the ME dipole. In the higher frequency band, $1\lambda $ modes of the E-dipole and the M-dipole are excited to form the $1\lambda $ mode of the ME dipole. In order to achieve compact structure and wide bandwidths, an SIW cavity is designed to feed the antenna. The proposed design shows that the measured impedance bandwidths (return loss larger than 10 dB) are 24–29.3 and 35.5–43.5 GHz at least with the achieved gain of 4.8–6.1 and 6.8–8.7 dBi, respectively. The designed antenna is suitable for 5G dual-band millimeter-wave applications. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

24. Melt Electrowriting Ordered TPU Microfibrous Mesh for On-Demand Colorimetric Wearable Sweat Detection.

Author

Shao, Zungui, Chen, Huatan, Wang, Qingfeng, Kang, Guoyi, Jiang, Jiaxin, Wang, Xiang, Li, Wenwang, Liu, Yifang, and Zheng, Gaofeng

Abstract

Fabric-based sweat sensors based on colorimetric analysis have the characteristics of simple structure, small size, convenience, and comfort, which are more suitable for vigorous exercise. However, the realization of on-demand detection of colorimetric sweat sensors is difficult. It will be invalid immediately once the detection process is activated, which may easily lead to ineffective detection. Therefore, the design and controllable fabrication of the sweat sampling layer is the key to improving the practicality of colorimetric sweat sensors. In this article, the hydrophobic thermoplastic polyurethane (TPU) flexible microfibrous mesh was controllably constructed by melt electrowriting and used as a sweat sampling layer to realize on-demand detection of colorimetric sweat sensor. The gating of different amounts of water can be achieved by precisely and orderly depositing the TPU microfiber meshes with different pore sizes and stacking layer numbers. Simultaneously, the optimal parameters of the TPU mesh were determined by the calibration experiment of the running test, which greatly improved the use efficiency (22 times) of the colorimetric sweat sensor.Moreover, the stability of the optimal sweat sensor was improved by 418% compared with the unoptimized one. The comfort and applicability of wearable sweat sensors in vigorous sports can be enhanced greatly by the controllable preparation of the TPU flexible microfiber meshes, which is helpful to promote the development of sweat sensors. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

30. Miniature Metamaterial Backward Wave Oscillator With a Coaxial Coupler.

Author

Tang, Xianfeng, Li, Xiangqiang, Wang, Qingfeng, Zhang, Jianqiong, Wang, Xin, Li, Shifeng, Zhang, Luqi, and Duan, Zhaoyun

Subjects
BACKWARD wave oscillators, SLOW wave structures, METAMATERIALS
Abstract

A coaxial coupler is proposed to develop a miniature metamaterial (MTM) backward wave oscillator (BWO). With respect to those using waveguide couplers as output structures, the MTM BWO adopting the coaxial coupler exhibits obvious miniaturized characteristics. For the MTM BWO, its high-frequency structure including the MTM slow wave structure (SWS) and the coaxial coupler has longitudinal length of $\sim 1.25\lambda $. ($\lambda $ is the free-space wavelength at the operating frequencies.) Importantly, the transverse size of $\sim \lambda $ /5 is only ~1/3 of those based on waveguide couplers. Furthermore, the transmission experiment is carried out. The experimental results show that the coaxial coupler with low loss property can effectively transform the TM-dominant mode in the MTM SWS to the TEM mode. The particle-in-cell simulations predict that the proposed MTM BWO yields MW-level peak output powers at frequencies from 2.85 to 2.903 GHz when the beam current is 30 A, and the beam voltage ranges from 65 to 110 kV. The simulation results confirm the feasibility of miniaturization as well as high output powers of the MTM BWO. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

40. Iterative consensus control for a class of nonlinear multi-agent systems with randomly varying iteration lengths

Author

Wang Sen, Liang Jiaqi, Wang Qingfeng, and Bu Xuhui

Subjects
0209 industrial biotechnology, Computer science, Multi-agent system, Iterative learning control, 02 engineering and technology, Tracking (particle physics), 01 natural sciences, Tracking error, Nonlinear system, 020901 industrial engineering & automation, 0103 physical sciences, Convergence (routing), 010301 acoustics, Random variable, Protocol (object-oriented programming), Algorithm
Abstract

In this paper, a distributed iterative learning control method was proposed for a class of nonlinear multi-agent systems consensus tracking, in which the systems trial lengths randomly varying. It is assumed that all agents have the same iterative learning length in one operation; however the operation lengths iteratively varying and a stochastic variable was introduced to describe non-uniform issue. With the control of proposed learning protocol, it is shown that the proposed algorithm guarantees the convergence of tracking error and repetitive multi-agent systems perform high precision tracking performance with randomly varying lengths. An illustrative example further verified the theoretical result.

Published
2019

41. Design Approach of Single-/Dual-Band Wilkinson Power Dividers with Single/Two Section Transmission Line Transformers

Author

Zhewang Ma, Xiaolong Wang, Wu Bin, Wang Qingfeng, and Chun-Ping Chen

Subjects
Computer science, 020208 electrical & electronic engineering, 020206 networking & telecommunications, 02 engineering and technology, Transmission line transformer, Topology, Network topology, law.invention, law, Transmission line, Harmonics, 0202 electrical engineering, electronic engineering, information engineering, Wilkinson power divider, Multi-band device, General topology, Transformer
Abstract

A design approach of single-/dual-band Wilkinson power dividers with single/two section transmission line transformers is summarized in this letter. Normally, two section transmission line transformer is well-known topology, which is not only used for single-band design application with compact circuit size and harmonics suppression, but also for dual-band circuit in other circuit topologies, such as Wilkinson power divider application. In this paper, several kinds of topologies could be summarized to a general topology with the same design equations and mathematical constraints. It is quite useful to understand the relationship among these topologies, meanwhile, it is also helpful for further circuit improvement.

Published
2019

42. LKSM: Light Weight Key-Value Store for Efficient Application Services on Local Distributed Mobile Devices.

Author

Li, Changlong, Zhuang, Hang, Wang, Qingfeng, Wang, Chao, and Zhou, Xuehai

Abstract

With the development of mobile network and corresponding techniques, more and more works focus on providing efficient services based on mobile devices. Furthermore, motivated by IoT, studies of local distributed mobile devices attract attentions of both industry and academia in recent years. However, existing storage systems cannot manage data and support the QoS of mobile services well. This paper presents LKSM, a light weight key-value storage system, which can be deployed on either one node or multiple nodes. To the best of our knowledge, it is the first attempt to propose key-value store in this scenario. We carefully analyze the challenges when designing the system on mobile clusters, and further propose RDS for addressing. With the help of RDS, LKSM achieves the goal of lower latency, better scalability, and higher availability. Furthermore, based on RDS, a novel data management strategy is presented, which successfully avoid energy holes of mobile clusters and achieves the tradeoff between performance and energy. We organize LKSM using a log-structured merge-tree and implement it based on LevelDB, an open source key-value storage system proposed by Google. Experiments on physical smartphones demonstrate that LKSM presents much higher performance compared with the ported LevelDB on mobile devices. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results