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RISS 인기검색어
- 검색키워드
- 저자 : He Qingqing (검색결과 5 건)
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LCL-T resonant network-based modular multi-channel constant-current LED driver analysis and design
He, Qingqing,Luo, Quanming,Huang, Jian,Cao, Chi,Sun, Pengju,Du, Xiong The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.6
Multiple output LED drivers are necessary to achieve better performance and higher reliability in street lighting, tunnel lighting and LCD background lighting applications. Based on LCL-T constant-current characteristics, a modular multiple output LED driver is proposed in this paper. The LCL-T rectifiers are connected to the same voltage bus and work like current sources. However, since there are much higher voltage harmonics in the AC square bus voltage, it is very important to quantitatively analyze how these harmonics influence the precision of the output currents. In addition, all of the switches can achieve Zero Voltage Switching (ZVS) by proper design of the LCL-T network. Finally, a 200-W prototype with five channels is established with an efficiency of 92.25%.
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Ning He,Qingqing Chen,Zhongxian Xu,Botao Bai,Chao Shen 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.1
A new event-triggered model predictive control (ET-MPC) algorithm is proposed for continuous perturbed nonlinear systems with constraints for the purpose of reducing computing burden and communication transmission. In the first step, an original event triggering condition is constructed based on the slope variation of the state error between the optimal prediction and the real state, i.e., the quasi quadratic differential (QQD) type eventtriggered mechanism. Secondly, the dual-mode control has been adopted to deal with the constrained nonlinear systems subject to disturbances, based on which the execution process of the proposed QQD based ET-MPC is described. In addition, the feasibility of the algorithm and closed-loop stability of the system have been strictly proved in theory. Lastly, two simulation examples are utilized to verify the effectiveness and applicability of the proposed algorithm.
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Ding Weijie,He Qingqing,Wang Yixin 한중경제문화학회 2024 한중경제문화연구 Vol.25 No.-
With the wave of digital economy sweeping the world, artificial intelligence, blockchain, cloud computing, 5G, ChatGPT and other information technologies are developing rapidly. All walks of life are undergoing changes, and people’s thinking, cognition, life, study, and work are changing accordingly. Both developed and developing countries are also facing new situations and challenges in politics, economy, science and technology, culture, and education. It can be said that digitalization itself and its impacts are related to the development of the future world and affect every citizen of the earth. Digital literacy and skills derived from digitalization have gradually become the focus of attention from all walks of life. In terms of college students’ digital literacy and digital literacy skills, it mainly refers to the digital ability that college students should have and use in study, employment, and future work under the background of informatization and digitalization. Although digital literacy and digital literacy skills have been paid more and more attention by the international community and schools, there is no unified definition of digital literacy and digital literacy skills by various countries and international organizations, and there are some differences in the use of this concept by countries and regions. From the perspective of enterprises’ demand for digital talents, this paper puts forward some suggestions on the training and improvement of college students’ digital literacy skills.
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ZIF-8 Modified Nanofiber Composite Window Screen for Efficient Indoor PM2.5 and Formaldehyde Removal
Fan Liu,Tong Lu,Wanjun Bu,Hewei Xiang,Junjie Yang,Junli Li,Xu Zhao,Weili Shao,Qingqing Ni,Jianxin He 한국섬유공학회 2022 Fibers and polymers Vol.23 No.8
Because people spend a lot of time indoors every day, the presence of particulate matter with a diameter less than2.5 μm (PM2.5) and volatile organic molecular substances in indoor air adversely affect public health. These toxic compoundscan be removed from the air using high-efficiency air-filter materials with adsorption capacity. Metal-organic frameworks(MOFs) are among the most suitable materials for air purification as they are synthetic porous materials with excellentadsorption ability. In this study, the zeolitic imidazolate framework-8 (ZIF-8) is uniformly grown on the surface ofpolyacrylonitrile (PAN) nanofibers using an in situ growth method to prepare ZIF-8@PAN nanofiber composite membranes. The nanofiber composite membrane effectively removes PM2.5 and formaldehyde from the air. After loading the optimalamount of ZIF-8, the filtration efficiency of the nanofiber membrane for salt aerosol with a diameter of 0.3 μm increases from90.3 % to 96.9 %, and the removal rate of formaldehyde becomes 98 % within 20 min in the enclosed space of the laboratory. Moreover, after five repeated tests, the formaldehyde adsorption rate remains above 80 %. In addition, ZIF-8@PANnanofiber membranes are used to fabricate anti-haze window screens, which have great potential to improve indoor airquality and mitigate related health risks.
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