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RISS 인기검색어
- 검색키워드
- 저자 : Siwen Yang (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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An E-capless AC-DC CRM Flyback LED Driver with Variable On-time Control
Yao, Kai,Bi, Xiaopeng,Yang, Siwen The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2
LED is a promising new generation of green lighting with the advantages of high efficiency, good optical performance, long lifetime and environmental friendliness. A pulsating current can be used to drive LEDs. However, current with a high peak-to-average ratio is unfavorable for LEDs. A novel control scheme for the ac-dc critical conduction mode (CRM) flyback LED driver is proposed in this paper. By using the input voltage, output voltage and average output current to control the turn-on time of the switch, the peak-to-average ratio of the output current can be reduced. The operation principle is analyzed and an implementation circuit is put forward. Experimental results show the effectiveness of the proposed scheme.
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An E-capless AC-DC CRM Flyback LED Driver with Variable On-time Control
Kai Yao,Xiaopeng Bi,Siwen Yang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2
LED is a promising new generation of green lighting with the advantages of high efficiency, good optical performance, long lifetime and environmental friendliness. A pulsating current can be used to drive LEDs. However, current with a high peak-to-average ratio is unfavorable for LEDs. A novel control scheme for the ac-dc critical conduction mode (CRM) flyback LED driver is proposed in this paper. By using the input voltage, output voltage and average output current to control the turn-on time of the switch, the peak-to-average ratio of the output current can be reduced. The operation principle is analyzed and an implementation circuit is put forward. Experimental results show the effectiveness of the proposed scheme.
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Review on oxidative desulfurization of fuel by supported heteropolyacid catalysts
Jiarong Li,Zhi Yang,Siwen Li,Qiping Jin,Jianshe Zhao 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.82 No.-
Desulfurization of fuel has been an important issue in fuel refining process. Hydrodesulfurization, as atraditional and commercial desulfurization technique for removing sulfur compounds, has been widelyresearched for decades. But as the environmental policy implemented on fuel becoming stricter, it ismore difficult to remove organic sulfur compounds by hydrodesulfurization technology. Therefore, nonhydrodesulfurizationtechnologies developed rapidly in recent years. Among all novel desulfurizationtechnologies, oxidative desulfurization (ODS) functions best with its mild reaction condition and efficientdesulfurization capacity. Heteropolyacid (HPA) has been intensively investigated because the HPA hasdiscrete ionic structure and high proton mobility, which makes it extremely promising in catalysis. As aresult, HPA has been applied in a variety of synthetically selective transformations of organic substancesand the ODS is one of them. However, HPA have shortcomings such as their high solubility in polarsolvents and low specific surface area. To overcome these problems, many works have been done tocombine heteropolyacids with other materials. The main derivatives of HPA used in ODS are supportedheteropolyacid, phase transfer heteropolyacid catalyst and polyoxometalate based ionic liquid. Thecatalytic activity and reusability of HPA are substantially increased after modification. The works onheteropolyaicds for ODS from 2010 to 2019 will be summarized in this review.
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Substrate effect on phonon in graphene layers
Xiao Guo,Yongsong Wang,Siwen You,Dingbang Yang,Guiping Jia,Fei Song,Weidong Dou,Han Huang 한국탄소학회 2023 Carbon Letters Vol.33 No.5
Graphene exhibits high carrier mobility and concentration as well as other remarkable properties. Among them, the thermal behaviors of phonon modes play important roles in the application of optical and electronic devices. Here, A–A stacked graphene were proved well by Raman investigation on G and 2D modes. Temperature-dependent Raman scattering measurements on graphene with various number of layers on different substrates were conducted in the temperature range of 80–460 K. The first-order temperature coefficient of single layer graphene (SLG) on SiO2/ Si substrate is obviously smaller than that on Cu foil, indicating that the substrate effect attributes a great impact on graphene phonon temperature dependence. The first-order temperature coefficients of multilayer graphene linearly decrease as the number of layers increases, attributed to the reduction of substrate effect in phonon behaviors, rather than to the anharmonic phonon–phonon (ph–ph) coupling or thermal expansion.
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