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200 results on '"Qi, Xuefeng"'

3. Hypercrosslinked polymers for supercapacitor applications

Author

Qi, Xuefeng and Dawson, Robert

Abstract

The use of fossil fuels has resulted in serious environmental problems such as pollution and global warming. Therefore, green and sustainable energy sources have been intensively researched and widely used. With the development of green energy, the demand for more effective energy storage devices to enhance energy efficiency has increased as well. Among all the energy storage devices, supercapacitors are known for high power density, long life span and fast charge/discharge rate. As a novel type of porous material, porous organic polymers (POPs) have promising potentials for supercapacitor applications because of their high porosity, tunable pore structures and functionalities, for example, covalent organic frameworks (COFs), such as conjugated microporous polymers (CMPs) have already shown good supercapacitive performance. In my work, hypercrosslinked polymer (HCP) materials are investigated for being used as supercapacitor electrode materials due to their ease of synthesis and low cost. Due to pore structures are closely related with supercapacitive performance, the pore structure controlling of HCPs is one of the main aims of this work. In chapter 3, the method for structure controlling is using monomers with different sizes and geometries. The HCPs synthesized from different monomers have BET surface areas varying from 127.1 m2 /g to 1255.6 m2 /g. The specific capacitances obtained at 2 mV/s of these HCPs vary from 2.2 F/g to 96 F/g. As heteroatom-doped activated carbons have shown increased supercapacitive performance, the monomers containing heteroatoms with different configurations are used for HCP synthesis in chapter 4 to investigate the effects of the heteroatom contents on the porous properties and supercapacitive performance of the HCPs. Compared with the non-doped HCPs, most of the heteroatom containing HCPs show a downward tendency in their BET surface areas. The oxygencontaining Diphenyl ether HCP and Dibenzofuran HCP show higher specific capacitances than other samples in this chapter, and the specific capacitances of these two samples are higher than those of their corresponding non-doped HCPs which are synthesized in chapter 3, indicating the oxygen content with some specific configurations could enhance the supercapacitive performance of the HCPs. In chapter 5, the method for HCP structure controlling is using different monomer to crosslinker ratios for HCP synthesis. With using different monomer to crosslinker ratios for HCPs synthesized from different monomers, the porous structures and specific capacitances of these HCPs are various. For Terphenyl HCPs, the BET surface areas of them vary from 34.5 m2 /g to 548.5 m2 /g while the specific capacitances of TPB HCPs range from 5.4 F/g to 113.8 F/g. The TPM HCP synthesized with a monomer to crosslinker ratio 1-6 has the highest BET surface area and highest specific capacitance in this work, 1783.5 m2 /g and 132.8 F/g, respectively. These results indicate that using different monomer to crosslinker ratios is an effective method for structure controlling of HCPs.

Published
2021

20. Evaluation Method of Aircraft Lightning Current Conduction Path Based on Numerical Simulation

Author

ZHEN Guoshuai, ZANG Jiazuo, and QI Xuefeng

Subjects
lightning protection, numerical simulation, conduction path design, Motor vehicles. Aeronautics. Astronautics, TL1-4050
Abstract

The lightning protection design and verification of aircraft are necessary measures to ensure the safety of pilots and aircraft, especially with the poor lightning protection ability of composite materials. The conductivity of the composite is weaker than that of the metal, which needs to provide additional pathways for the lightning current conduction. Based on the electromagnetic modeling of aircraft internal structure rarely mentioned in domestic related research, a set of electromagnetic modeling and precision control method for aircraft internal structure is proposed, and the internal metal structure from left wing to right wing of F22 aircraft is constructed as lightning current conduction path. The indirect effect of aircraft lightning is simulated based on general electromagnetic simulation software. The simulation results of electromagnetic field and cable coupling in aircraft interior under three conditions of composite skin, metal mesh skin, and metal mesh skin with internal metal structure are compared. The results show that the reasonable lightning current conduction path design can reduce the current intensity induced by the cable inside the aircraft by half, and play a good lightning protection effect. The proposed evaluation method is suitable for the lightning current conduction path design of fixed wing aircraft, can be taken as the indexes distribution reference frame of aircraft airborne equipment lightning indirect effect test, and is convenient for locating the weak links of aircraft lightning indirect effect protection.

Published
2021
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25. Extracellular vesicles derived from PPRV-infected cells enhance signaling lymphocyte activation molecular (SLAM) receptor expression and facilitate virus infection

Author

Chen, Yan, primary, Wang, Ting, additional, Yang, Yang, additional, Fang, Yuan, additional, Zhao, Bao, additional, Zeng, Wei, additional, Lv, Daiyue, additional, Zhang, Leyan, additional, Zhang, Yanming, additional, Xue, Qinghong, additional, Chen, Xiwen, additional, Wang, Jingyu, additional, and Qi, Xuefeng, additional

Published
2022
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30. Comparative clinical studies of primary chemoradiotherapy versus S-1 and nedaplatin chemotherapy against stage IVb oesophageal squamous cell carcinoma: a multicentre open-label randomised controlled trial

Author

Liu, Yun, primary, Beeraka, Narasimha M, additional, Liu, Junqi, additional, Chen, Kuo, additional, Song, Bo, additional, Song, Zhang, additional, Luo, Jianchao, additional, Liu, Yang, additional, Zheng, Anping, additional, Cui, Yanhui, additional, Wang, Yang, additional, Jia, Zhenhe, additional, Song, Xiangyu, additional, Wang, Xiaohong, additional, Wang, Hongqi, additional, Qi, Xuefeng, additional, Ren, Jinshan, additional, Wu, Liping, additional, Cai, Jixing, additional, Fang, Xainying, additional, Wang, Xin, additional, Sinelnikov, Mikhail Y, additional, Nikolenko, Vladimir N, additional, Greeshma, M V, additional, and Fan, Ruitai, additional

Published
2022
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42. Reach on Dynamic EME Adaptability in Battlefield Based on System Synergy

Author

Qi Xuefeng, Zhen Guoshuai, Yan Wang, and Mao Yu

Subjects
Electromagnetic spectrum, Process (engineering), Computer science, media_common.quotation_subject, Electromagnetic compatibility, Systems engineering, Design process, ComputerApplications_COMPUTERSINOTHERSYSTEMS, Electronics, Avionics, Modern warfare, Adaptability, media_common
Abstract

With the development of electronic technology and the improvement of electromagnetic spectrum warfare theory, the EME of the future battlefield is becoming more and more complex and changeable. Modern warfare is no longer a single force or single equipment operation, integrated joint operation has gradually become the development trend of modern high-tech war. The EME adaptability of weapons and equipments is directly related to the initiative in the war. Aiming at the urgent requirement to improve the adaptability and combat capability of weapons and equipments in complex EME, by means of electromagnetic simulation, the operational style and operational process of typical avionics are analyzed, the composition and characteristic elements of battlefield EME are studied, the scene model of battlefield dynamic EME are built. With the combat scenario and typical mission profile, communication link and interference link are taken as the evaluation object, and the real-time EME adaptability of weapons and equipments is analyzed by electromagnetic hybrid algorithm. The electromagnetic simulation is extended from platform level to scene level, and the electromagnetic effect of system cooperative operation is incorporated into the EMC design process. This method can not only be used to evaluate the EME adaptability in the operational task process of weapon and equipment, but also provide strong support for the design of RF compatibility and tactical performance of warplane.

Published
2020

43. Application of Neural Network Analysis Based on Bayesian Regularization in Crosstalk of Cable

Author

Yan Wang, Zhen Guoshuai, and Qi Xuefeng

Subjects
Coupling, Twisted pair, Crosstalk (biology), Artificial neural network, Transmission line, Computer science, law, Reliability (computer networking), Electromagnetic compatibility, Function (mathematics), Algorithm, law.invention
Abstract

In this paper, an artificial neural network based on Bayesian regularization training function is constructed for the internal twisted pair electromagnetic crosstalk system of aircraft. The crosstalk coupling current on the disturbed line is used as the training data of neural network and the coupling current is calculated by multi-conductor transmission line theory. The prediction results show that the prediction value of neural network based on Bayesian regularization training function is close to the input value, and the regression analysis shows that the prediction reliability of network is high, so it can be applied to the prediction of twisted pair electromagnetic crosstalk system.

Published
2020

44. Research on Shielding Effectiveness Evaluation Method of Materials with Fine Complex Structure

Author

Zhen Guoshuai, Yan Wang, Qi Xuefeng, and Mao Yu

Subjects
Electromagnetics, Materials science, Mesh generation, Electric field, Electromagnetic shielding, Electromagnetic compatibility, Computational electromagnetics, Mechanical engineering, Real structure, Magnetic field
Abstract

New materials with fine and complex structures are widely used in multifunctional materials. Aiming at the difficulty of mesh generation and electromagnetic simulation of shielding effectiveness of the electromagnetic model used the materials with fine and complex structures, according to the distribution of electric field and magnetic field on the surface of the material structure unit, the equivalent electromagnetic parameters are deduced and the equivalent simulation model is established. The equivalent material model is established, the equivalent model and the real structure model of infinite plate are simulated. The simulation results of shielding effectiveness differ 0.1 dB, the results are in good agreement with each other. This equivalent simulation method can be used to evaluate the shielding effectiveness of materials with fine complex structure and realize the equivalent simulation of large irregular electromagnetic model.

Published
2020

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