Improving Dielectric Properties in Novel P(VDF‑HFP)/V2AlC MAX/Montmorillonite Composite Films via Interfacial Electric‑Leakage Depressing Strategy

Xiaofeng Xia,Junquan Zhou,Huimin Ding,Qin Li,Maolin Bo,Qihuang Deng,Yefeng Feng 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.1

Dielectric constants of polymer/conductor composites are often high, owing to strong interface interaction in those composites. They can be used for dielectric energy storage, but they usually have high dielectric loss and conductivity. In order toreduce the dielectric loss and conductivity in poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP))/V2AlC MAXcomposites, in this study, we explored the novel P(VDF-HFP)/V2AlC MAX/montmorillonite (MMT) ternary composites. Compared with binary composites, the ternary composites showed the mildly reduced dielectric constant, significantlydecreased dielectric loss and conductivity. Using highly-conductive V2AlCMAX filler aimed at taking advantage of thepolymer/MAX interface polarization to increase the dielectric response of composites. Employing well-insulating MMTfiller aimed at reducing the interface electric leakage conduction. At 1 kHz, the outstanding ternary composite with 2 wt%MMT and 20 wt% MAX could exhibit a high dielectric constant of ca. 27 and low dielectric loss of ca. 0.21. This workmight offer a new research idea for the construction of high-performance composite dielectric films containing modernMAX ceramic fillers.

Electrochemical properties of Bi-Ni and Bi-Ni-Mn composite-coated electrolytic manganese dioxide

Xiaofeng Li,Zhigang Huang,Tongchi Xia,Huichao Dong,Yanghua Song 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.6

The Bi-Ni and Bi-Ni-Mn composite is separately coated on the surface of commercial electrolytic manganesedioxide (EMD) by using a simple chemical precipitation/oxidation method. The results of X-ray diffractionshow that a structure of γ-MnO2 is kept for all the coated EMD, but the intensity of their diffraction peaks is lower thanuncoated one. Both the Bi0.5-Ni0.5 and Bi0.35-Ni0.35-Mn0.3 composite benefits the discharge capacity and high-power performanceof the EMD electrodes. On the other hand, the results of scanning electron microscopy and energy dispersivespectroscopy confirm the more uniform distribution of the Bi0.15-Ni0.55-Mn0.3 composite on the surface of EMD thanthe Bi0.5-Ni0.5 one, thereby resulting in better cyclability of the electrodes. After 50 cycles at a 1C rate, the capacity retentionrate of the Bi0.15-Ni0.55-Mn0.3 composite-coated electrode reaches to 80%, which is far larger than the un-coated(49%) and the Bi0.5-Ni0.5 composite-coated (63%) one.

Research on Grid Side Power Factor of Unity Compensation Method for Matrix Converters

Xia, Yihui,Zhang, Xiaofeng,Ye, Zhihao,Qiao, Mingzhong The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

Input filters are very important to matrix converters (MCs). They are used to improve grid side current waveform quality and to reduce the input voltage distortion supplied to the grid side. Due to the effects of the input filter and the output power, the grid side power factor (PF) is not at unity when the input power factor angle is zero. In this paper, the displacement angle between the grid side phase current and the phase voltage affected by the input filter parameters and output power is analyzed. Based on this, a new grid side PF unity compensation method implemented in the indirect space vector pulse width modulation (ISVPWM) method is presented, which has a larger compensation angle than the traditional compensation method, showing a higher grid side PF at unity in a wide output power range. Simulation and experimental results verify that the analysis of the displacement angle between the grid side phase current and the phase voltage affected by the input filter and output power is right and that the proposed compensation method has a better grid side PF at unity.

Application of advanced spectral-ratio radon background correction in the UAV-borne gamma-ray spectrometry

Xia Jigen,Song Baolin,Gu Yi,Li Zhiqiang,Xu Jie,Ge Liangquan,Zhang Qingxian,Zeng Guoqiang,Liu Qiushi,Yang Xiaofeng 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8

The influence of the atmospheric radon background on the airborne gamma spectrum can seriously affect researchers’ judgement of ground radiation information. However, due to load and endurance, unmanned aerial vehicle (UAV)-borne gamma-ray spectrometry is difficulty installing upward-looking detectors to monitor atmospheric radon background. In this paper, an advanced spectral-ratio method was used to correct the atmospheric radon background for a UAV-borne gamma-ray spectrometry in Inner Mongolia, China. By correcting atmospheric radon background, the ratio of the average count rate of U window in the anomalous radon zone (S5) to that in other survey zone decreased from 1.91 to 1.03, and the average uranium content in S5 decreased from 4.65 mg/kg to 3.37 mg/kg. The results show that the advanced spectral-ratio method efficiently eliminated the influence of the atmospheric radon background on the UAV-borne gamma-ray spectrometry to accurately obtain ground radiation information in uranium exploration. It can also be used for uranium tailings monitoring, and environmental radiation background surveys

A network traffic prediction model of smart substation based on IGSA-WNN

Xia, Xin,Liu, Xiaofeng,Lou, Jichao Electronics and Telecommunications Research Instit 2020 ETRI Journal Vol.42 No.3

The network traffic prediction of a smart substation is key in strengthening its system security protection. To improve the performance of its traffic prediction, in this paper, we propose an improved gravitational search algorithm (IGSA), then introduce the IGSA into a wavelet neural network (WNN), iteratively optimize the initial connection weighting, scalability factor, and shift factor, and establish a smart substation network traffic prediction model based on the IGSA-WNN. A comparative analysis of the experimental results shows that the performance of the IGSA-WNN-based prediction model further improves the convergence velocity and prediction accuracy, and that the proposed model solves the deficiency issues of the original WNN, such as slow convergence velocity and ease of falling into a locally optimal solution; thus, it is a better smart substation network traffic prediction model.

Research on Grid Side Power Factor of Unity Compensation Method for Matrix Converters

Yihui Xia,Xiaofeng Zhang,Zhihao Ye,Mingzhong Qiao 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

Input filters are very important to matrix converters (MCs). They are used to improve grid side current waveform quality and to reduce the input voltage distortion supplied to the grid side. Due to the effects of the input filter and the output power, the grid side power factor (PF) is not at unity when the input power factor angle is zero. In this paper, the displacement angle between the grid side phase current and the phase voltage affected by the input filter parameters and output power is analyzed. Based on this, a new grid side PF unity compensation method implemented in the indirect space vector pulse width modulation (ISVPWM) method is presented, which has a larger compensation angle than the traditional compensation method, showing a higher grid side PF at unity in a wide output power range. Simulation and experimental results verify that the analysis of the displacement angle between the grid side phase current and the phase voltage affected by the input filter and output power is right and that the proposed compensation method has a better grid side PF at unity.

A Truthful and Low-Overhead Routing Protocol for Ad Hoc Networks

Dongbin Wang,Xiaofeng Wang,Xiangzhan Yu,Kaicheng Qi,Zhibin Xia 보안공학연구지원센터 2013 International Journal of Future Generation Communi Vol.6 No.2

Stem cells from human exfoliated deciduous teeth attenuate trigeminal neuralgia in rats by inhibiting endoplasmic reticulum stress

Yang, Zhijie,Wang, Chun,Zhang, Xia,Li, Jing,Zhang, Ziqi,Tan, Zhao,Wang, Junyi,Zhang, Junyang,Bai, Xiaofeng The Korean Pain Society 2022 The Korean Journal of Pain Vol.35 No.4

Background: The treatment of trigeminal neuralgia remains a challenging issue. Stem cells from human exfoliated deciduous teeth (SHED) provide optimized therapy for chronic pain. This study aimed to investigate the mechanisms underlying the attenuation of trigeminal neuralgia by SHED. Methods: Trigeminal neuralgia was induced by chronic constriction injury of the infraorbital nerve. The mechanical threshold was assessed after model establishment and local SHED transplantation. Endoplasmic reticulum (ER) morphology and Caspase12 expression in trigeminal ganglion (TG) was evaluated as well. BiP expression was observed in PC12 cells induced by tunicamycin. Results: The local transplantation of SHED could relieve trigeminal neuralgia in rats. Further, transmission electron microscopy revealed swelling of the ER in rats with trigeminal neuralgia. Moreover, SHED inhibited the tunicamycin-induced up-regulated expression of BiP mRNA and protein in vitro. Additionally, SHED decreased the up-regulated expression of Caspase12 mRNA and protein in the TG of rats caused by trigeminal neuralgia after chronic constriction injury of the infraorbital nerve mode. Conclusions: This findings demonstrated that SHED could alleviate pain by relieving ER stress which provide potential basic evidence for clinical pain treatment.

Realizing Rationally-Balanced Dielectric Properties in Fluoropolymer/Cr2AlC MAX Composites Modified by 2D-BN

Qin Li,Junquan Zhou,Yanhui Chen,Xiaofeng Xia,Maolin Bo,Qihuang Deng,Yefeng Feng 한국고분자학회 2020 Macromolecular Research Vol.28 No.13

Polymer/conductor composite dielectric materials have a high dielectric constant. In recent years, composite dielectrics have become a study hotspot in highdensity energy storage capacitors. However, high dielectric loss and high electrical conductivity make the application of the composite materials very limited. In order to obtain composite materials with high dielectric constant, low dielectric loss and low conductivity, we added the insulating boron nitride (BN) filler into polymer/Cr2AlC composites. As a conductive filler, Cr2AlC ternary-layered-compound (MAX) ceramic has an interface polarization with the polymer matrix, thereby increasing the dielectric constant of the composites. The insulating BN has a very low electrical conductivity, which can effectively reduce the electrical conductivity and dielectric loss of the composites. Compared with the binary polymer/Cr2AlC composite materials, the ternary polymer/Cr2AlC/BN composite materials can achieve the low dielectric loss and low conductivity as well as properly-lowered dielectric constant. The ternary composite material filled with 10 wt% Cr2AlC and 2 wt% BN has a dielectric constant of about 30, a dielectric loss of about 0.7 and a conductivity of about 4.6×10- 7 S m-1 at 100 Hz. In this work, high-performance composite dielectrics were prepared through good cooperation between conductive and insulating ceramic fillers, which might provide an idea for design of promising energy storage capacitors.