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8 results on '"Xunyu Liu"'

1. Co3O4 Supported on Graphene-like Carbon by One-Step Calcination of Cobalt Phthalocyanine for Efficient Oxygen Reduction Reaction under Alkaline Medium

Author

Huang Tan, Xunyu Liu, Miaohui Wang, Hui Huang, and Peipei Huang

Subjects
Co3O4, graphene-like carbon, oxygen reduction reaction, one-step calcination, cobalt phthalocyanine, Chemistry, QD1-999
Abstract

Exploiting cost-effective and durable non-platinum electrocatalysts for oxygen reduction reaction (ORR) is of great significance for the development of abundant renewable energy conversion and storage technologies. Herein, a series of Co3O4 supported on graphene-like carbon (Co3O4/C) samples were firstly effectively synthesized by one-step calcination of cobalt phthalocyanine and their electrocatalytic performances were measured for ORR under an alkaline medium. By systematically adjusting the calcination temperature of cobalt phthalocyanine, we found that the material pyrolyzed at 750 °C (Co3O4/C−750) shows the best ORR electrocatalytic performance (half-wave potentials of 0.77 V (vs. RHE) in 0.1 M KOH) among all the control samples. Moreover, it displays better stability and superior methanol tolerance than commercial 20% Pt/C. The further electrochemical test results reveal that the process is close in characteristics to the four-electron ORR process on Co3O4/C−750. In addition, Co3O4/C−750 applied in the zinc–air battery presents 1.34 V of open circuit potential. Based on all the characterizations, the enhanced electrocatalytic performances of Co3O4/C−750 composite should be ascribed to the synergistic effect between Co3O4 and the graphene-like carbon layer structure produced by pyrolysis of cobalt phthalocyanine, as well as its high specific surface area.

Published
2023
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2. A New MMC Sub-Module Topology with DC Fault Blocking Capability and Capacitor Voltage Self-Balancing Capability

Author

Yuqi Pang, Gang Ma, Xunyu Liu, Xiaotian Xu, and Xinyuan Zhang

Subjects
modular multilevel inverter, DC fault clearing ability, improved sub-module topology, voltage self-balancing ability, Technology
Abstract

A large number of modular multilevel converters (MMC) are connected to HVDC transmission systems nowadays. This paper aims at the short-circuit fault in the DC line of the HVDC transmission system and the problem of capacitor voltage imbalance in MMC, proposing a new type of MMC sub-module, which has both the DC fault self-clearing ability and the capacitor voltage self-balancing ability. This sub-module combines the topology of half bridge and full bridge. It uses the reverse capacitor voltage to forcibly turn off the conducting diode to block the fault current loop. At the same time, the two capacitances charge and discharge states are consistent by utilizing the operating mode of the sub-module. It is possible to directly achieve a self-balancing capacitor voltage without complex balancing voltage control. The MATLAB/Simulink simulation verifies the effectiveness of the DC fault blocking capability and capacitor voltage balance capability of the proposed sub-module.

Published
2021
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5. Crack-Across-Pore Enabled High-Performance Flexible Pressure Sensors for Deep Neural Network Enhanced Sensing and Human Action Recognition

Author

Yuxin Hou, Lei Wang, Ran Sun, Yuanao Zhang, Mengxi Gu, Yuanhao Zhu, Yubo Tong, Xunyu Liu, Zhixun Wang, Juan Xia, Yougen Hu, Lei Wei, Chunlei Yang, and Ming Chen

Subjects
Wearable Electronic Devices, Nanotubes, Carbon, General Engineering, Pressure, General Physics and Astronomy, Humans, General Materials Science, Neural Networks, Computer, Pattern Recognition, Automated
Abstract

Flexible pressure sensors with high sensitivity over a broad pressure range are highly desired, yet challenging to build to meet the requirements of practical applications in daily activities and more significant in some extreme environments. This work demonstrates a thin, lightweight, and high-performance pressure sensor based on flexible porous phenyl-silicone/functionalized carbon nanotube (PS/FCNT) film. The formed crack-across-pore endows the pressure sensor with high sensitivity of 19.77 kPa

Published
2022

6. Research on Topology, Control and Simulation of DVR

Author

Xinyuan Zhang, Xiaotian Xu, Xunyu Liu, and Yuqi Pang

Subjects
Topology control, Computer science, General Engineering, Topology (electrical circuits), AC power, Transient voltage suppressor, Power (physics), Control theory, Power module, General Earth and Planetary Sciences, MATLAB, computer, General Environmental Science, computer.programming_language, Voltage
Abstract

Dynamic voltage restorer (DVR) is a series compensation device with energy storage device, which can compensate reactive power and active power. DVR is composed of power module, action module, control module and sampling module. The core of the research lies in its topology and control strategy. This paper starts from the above two aspects, studies the working principle and structural characteristics of the dynamic voltage restorer, and analyzes the topological structure and the function of the structure of the dynamic voltage restorer. A voltage and current double closed-loop control strategy is proposed, which can effectively compensate the transient voltage. A DVR model is built in Matlab/Simulink, and power failure and three-phase short circuit are simulated. A double closed-loop control strategy based on voltage and current is applied. The simulation results show the feasibility and effectiveness of the control strategy.

Published
2020

7. Research on Household Energy Control Method Based on Electric Vehicle

Author

Yuqi Pang, Xiaotian Xu, Xinyuan Zhang, and Xunyu Liu

Subjects
business.product_category, Mains electricity, business.industry, Computer science, 020209 energy, General Engineering, Automotive industry, Particle swarm optimization, 020206 networking & telecommunications, Environmental pollution, 02 engineering and technology, Grid, Automotive engineering, Power (physics), Computer Science::Robotics, Hardware_GENERAL, Electric vehicle, 0202 electrical engineering, electronic engineering, information engineering, General Earth and Planetary Sciences, Electricity, business, General Environmental Science
Abstract

With the development of the automobile industry, the extensive use of automobiles is a key factor in the global energy crisis and environmental pollution, and the clean and environmentally friendly characteristics of electric vehicles have become an ideal means to deal with these two major problems. Connecting household electric vehicles to the home will not only affect the distribution network, but also adversely affect the home electricity network. Therefore, it is necessary to connect electric vehicles to household charging load for quantitative analysis, so as to design energy control methods for electric vehicles to connect to households, and minimize the adverse effects of electric vehicles connected to household power grids. First of all, this article analyzes the uncertainty of electric vehicle access to the grid. After considering the random characteristics of electric vehicle charging load, an electric vehicle charging load model is built based on Monte Carlo simulation. Secondly, according to the electric vehicle charging load power curve obtained by the above method, combined with the daily load probability model of the grid, a household electricity model is established. Finally, based on the Particle Swarm Optimization(PSO), a family energy control method is proposed, and the optimization goal is to minimize the daily load fluctuation of the family, so as to minimize the impact of electric vehicles connected to the grid.

Published
2020

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