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Analysis and Design of Function Decoupling High Voltage Gain DC/DC Converter
Wei, Yuqi,Luo, Quanming,Lv, Xingyu,Sun, Pengju,Du, Xiong The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2
Traditional boost converters have difficulty realizing high efficiency and high voltage gain conversion due to 1) extremely large duty cycles, 2) high voltage and current stresses on devices, and 3) low conversion efficiency. Therefore, a function decoupling high voltage gain DC/DC converter composed of a DC transformer (DCX) and an auxiliary converter is proposed. The role of DCX is to realize fixed gain conversion with high efficiency, whereas the role of the auxiliary converter is to regulate the output voltage. In this study, different forms of combined high voltage gain converters are compared and analyzed, and a structure is selected for the function decoupling high voltage gain converter. Then, topologies and control strategies for the DCX and auxiliary converter are discussed. On the basis of the discussion, an optimal design method for circuit parameters is proposed, and design procedures for the DCX are described in detail. Finally, a 400 W experimental prototype based on the proposed optimal design method is built to verify the accuracy of the theoretical analysis. The measured maximum conversion efficiency at rated power is 95.56%.
Analysis and Design of Function Decoupling High Voltage Gain DC/DC Converter
Yuqi Wei,Quanming Luo,Xingyu Lv,Pengju Sun,Xiong Du 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2
Traditional boost converters have difficulty realizing high efficiency and high voltage gain conversion due to 1) extremely large duty cycles, 2) high voltage and current stresses on devices, and 3) low conversion efficiency. Therefore, a function decoupling high voltage gain DC/DC converter composed of a DC transformer (DCX) and an auxiliary converter is proposed. The role of DCX is to realize fixed gain conversion with high efficiency, whereas the role of the auxiliary converter is to regulate the output voltage. In this study, different forms of combined high voltage gain converters are compared and analyzed, and a structure is selected for the function decoupling high voltage gain converter. Then, topologies and control strategies for the DCX and auxiliary converter are discussed. On the basis of the discussion, an optimal design method for circuit parameters is proposed, and design procedures for the DCX are described in detail. Finally, a 400 W experimental prototype based on the proposed optimal design method is built to verify the accuracy of the theoretical analysis. The measured maximum conversion efficiency at rated power is 95.56%.
Fan Xia,Xuexin Yu,Yunke Li,Yuqi Chen,Wei Zhang,Chao You,Xin Hu 대한뇌졸중학회 2020 Journal of stroke Vol.22 No.3
Background and Purpose As a leading cause of disability and death in China, stroke as well as its epidemiologic features have gained increasing attention. Prior studies, however, have overgeneralized the north-to-south gradient in China. Whether the differences exist across urban and rural areas remains unexplored. This study therefore aims to investigate the north-to-south gradient in stroke incidence across urban and rural China. Methods The present prospective cohort study analyzed data from the China Health and Nutrition Survey 1997 to 2015. By including 16,917 individuals from diverse social contexts, we calculated the age-standardized incidence of stroke across regions and the age-adjusted risk ratio (aRR). Cox proportional hazards models with time-varying covariates were employed to analyze variations in incident stroke. Results During the follow-up, age-standardized incidence of stroke ranged from 4.17 per 1,000 person-years (95% confidence interval [CI], 3.38 to 4.96) in the north region to 1.95 (95% CI, 1.60 to 2.30) in the south region (aRR, 2.04; 95% CI, 1.58 to 2.64; P<0.001). The north-to-south gradient of stroke incidence was observed only in rural areas, but not in urban areas. Hierarchical modelling analyses further indicated that the regional differences could be mostly explained by the disparities in the prevalence of hypertension. Conclusions The present study extends the current evidence on the north-to-south gradient by demonstrating that the difference varied across urban and rural China. Our findings highlight the importance of hypertension management as the measure for alleviating regional differences in stroke incidence.
Fu, Boshi,Park, Yoojin,Kim, Ki Tae,Chen, Kun,Zou, Guangrong,Wei, Qi,Peng, Shuang,Chen, Yuqi,Kim, Byeang Hyean,Zhou, Xiang The Royal Society of Chemistry 2018 Chemical communications Vol.54 No.81
<P>Herein, we have developed a novel fluorescence labeling strategy for nucleic acid aptamers based on self-assembling between AGG tri-nucleotide repeats and a pyrene-modified oligonucleotide. This strategy could be an effective tool for developing targeting-imaging systems and biosensor systems to detect target molecules.</P>