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- 저자 : Huipeng Li (검색결과 3 건)
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Analysis of synonymous codon usage of chloroplast genome in Porphyra umbilicalis
Guoling Li,Zonglian Pan,Shichen Gao,Yuyang He,Qiaoyu Xia,Yan Jin,Huipeng Yao 한국유전학회 2019 Genes & Genomics Vol.41 No.10
Background Synonymous codon usage bias is noticed in the genome of every organism, influenced by mutation pressure and natural selection. The analysis of codon usage pattern in Porphyra umbilicalis chloroplast genome are inferred while previous study focused on codon bias in nuclear genome. Objective To develop a better understanding of the factors affecting synonymous codon usage, codon usage patterns and nucleotide composition of 150 genes in P. umbilicalis cp genome, and provide a theoretical basis for genetic modification of chloroplast genome. Methods In this study, all codon usage bias parameters and nucleotide compositions were calculated by Python script, Codon W, DNA Star, CUSP of EMBOSS and Microsoft Excel. Results It shows that codon usage models are mainly influenced by compositional constraints under mutational pressure and synonymous codon prefers to use codons ending with A/T, comparing to C/G. The ENC value is slight low which shows the weak codon bias. For all coding genes of P. umbilicalis chloroplast genome except Photosystem I genes, a weak correlation between GC3 and GC12 suggests natural selection might play a significant role in synonymous codon usage bias. Conclusion The codon usage bias in P. umbilicalis cp genome is low and in some way or other, influenced by natural selection, mutation pressure, nucleotide composition. Our results can provide a theoretical basis for codon modification of exogenous genes, accuracy of prediction about new members of chloroplast gene family and identification of unknown genome.
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Investigation of the Voltage Collapse Mechanism in Three-Phase PWM Rectifiers
Chunguang Ren,Huipeng Li,Yu Yang,Xiaoqing Han,Peng Wang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.5
Three-phase pulse width modulation (PWM) rectifiers are usually designed under the assumption of ideal ac power supply and input inductance. However, non-ideal circuit parameters may lead to a voltage collapse of PWM rectifiers. This paper investigates the mechanism of voltage collapse in three-phase PWM rectifiers. An analytical stability boundary expression is derived by analyzing the equilibrium point of the averaging state space model, which can not only accurately locate the voltage collapse boundary in the circuit parameter domain, but also reveal the essential characteristic of the voltage collapse. Results are obtained and compared with those of the trial-error method and the Jacobian method. Based on the analysis results, the system parameters can be divided into two categories. One of these categories affects the critical point, and other affects only the instability process. Furthermore, an effective control strategy is proposed to prevent a vulnerable system from being driven into the instability region. The analysis results are verified by the experiments.
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Investigation of the Voltage Collapse Mechanism in Three-Phase PWM Rectifiers
Ren, Chunguang,Li, Huipeng,Yang, Yu,Han, Xiaoqing,Wang, Peng The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.5
Three-phase pulse width modulation (PWM) rectifiers are usually designed under the assumption of ideal ac power supply and input inductance. However, non-ideal circuit parameters may lead to a voltage collapse of PWM rectifiers. This paper investigates the mechanism of voltage collapse in three-phase PWM rectifiers. An analytical stability boundary expression is derived by analyzing the equilibrium point of the averaging state space model, which can not only accurately locate the voltage collapse boundary in the circuit parameter domain, but also reveal the essential characteristic of the voltage collapse. Results are obtained and compared with those of the trial-error method and the Jacobian method. Based on the analysis results, the system parameters can be divided into two categories. One of these categories affects the critical point, and other affects only the instability process. Furthermore, an effective control strategy is proposed to prevent a vulnerable system from being driven into the instability region. The analysis results are verified by the experiments.
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