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An Improved Active Damping Method with Capacitor Current Feedback
Yi-Wen Geng,Ya-Wen Qi,Hai-Wei Liu,Fei Guo,Peng-Fei Zheng,Yong-Gang Li,Wen-Ming Dong 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2
Proportional capacitor current feedback active damping (CCFAD) has a limited valid damping region in the discrete time domain as (0, fs/6). However, the resonance frequency (fr) of an LCL-type filter is usually designed to be less than half the sampling frequency (fs) with the symmetry regular sampling method. Therefore, (fs/6, fs/2) becomes an invalid damping region. This paper proposes an improved CCFAD method to extend the valid damping region from (0, fs/6) to (0, fs/2), which covers all of the possible resonance frequencies in the design procedure. The full-valid damping region is obtained and the stability margin of the system is analyzed in the discrete time domain with the Nyquist criterion. Results show that the system can operate stably with the proposed CCFAD method when the resonance frequency is in the region (0, fs/2). The performances at the steady and dynamic state are enhanced by the selected feedback coefficient H and controller gain Kp. Finally, the feasibility and effectiveness of the proposed CCFAD method are verified by simulation and experimental results.
An Improved Active Damping Method with Capacitor Current Feedback
Geng, Yi-Wen,Qi, Ya-Wen,Liu, Hai-Wei,Guo, Fei,Zheng, Peng-Fei,Li, Yong-Gang,Dong, Wen-Ming The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2
Proportional capacitor current feedback active damping (CCFAD) has a limited valid damping region in the discrete time domain as (0, $f_s/6$. However, the resonance frequency ($f_r$) of an LCL-type filter is usually designed to be less than half the sampling frequency ($f_s$) with the symmetry regular sampling method. Therefore, ($f_s/6$, $f_s/2$) becomes an invalid damping region. This paper proposes an improved CCFAD method to extend the valid damping region from (0, $f_s/6$ to (0, $f_s/2$), which covers all of the possible resonance frequencies in the design procedure. The full-valid damping region is obtained and the stability margin of the system is analyzed in the discrete time domain with the Nyquist criterion. Results show that the system can operate stably with the proposed CCFAD method when the resonance frequency is in the region (0, $f_s/2$). The performances at the steady and dynamic state are enhanced by the selected feedback coefficient H and controller gain $K_p$. Finally, the feasibility and effectiveness of the proposed CCFAD method are verified by simulation and experimental results.
Thiamethoxam Induces Meiotic Arrest and Affects Embryo Developmental Potential of Bovine Oocytes
Zheng-Wen Nie,Ying-Jie Niu,Wenjun Zhou,Yong-Han Kim,Kyung-Tae Shin,Xiang-Shun Cui 한국수정란이식학회 2018 한국수정란이식학회 학술대회 Vol.2018 No.11
Thiamethoxam (TMX) is a neonicotinoid insecticide. Residues of TMX have been detected in various crops. Although it has specific high toxicity to insects and is designed to exterminate them, the toxicity has also found in mammals recently. Differ from acetylcholine toxicity, TMX has peroxide toxicity in mammals. Matured oocytes have the capacity of fertilization, but oocytes own abundant mitochondria and its maturation is vulnerable to reactive oxygen species (ROS). Excessive production of reactive oxygen species (ROS) can override antioxidant defenses, produce oxidative stress and DNA damage that triggers apoptosis and necrosis in organisms. However little is known about the harm of ROS induced by TMX during oocytes maturation. Here, bovine germ-vesicle (GV) oocytes were cultured to metaphase of the second meiosis (MII) stage in vitro with or without TMX. During this process, oocytes were evaluated by various methods. Microscopic examination showed that 1.6 mM TMX significantly inhibited the maturation process in which oocytes were arrested before MI stage or between MI and MII stage. Correspond to this two periods, immunofluorescence staining and enzyme activity analysis showed that active CDC25 and CDC2 reduced in TMX group compared to control; time lapse and immunofluorescence staining gave results that Cyclin B could not be degraded, actin cap could not form, and Bub3 could not be removed from kinetochores. In addition, MII oocytes exposed to TMX showed disordered chromosomes and spindle. To study further, oocytes cultured for 24 h were analyzed. On the one hand, these oocytes in TMX group accumulated more ROS and produced significantly decreased mitochondrial membrane potential and increased apoptotic signal compared to control by methods of quantities for dichlorodihydrofluorescein diacetate (DCHFDA), 5,5′,6,6′-Tetrachloro-1,1′,3,3′-tetraethyl-imidacarbocyanine iodide and Annexin-V, but the level of γH2AX protein in TMX group did not decline significantly compared with control. On the another hand, these oocytes were activated to be parthenogenetic embryos and cultured. Assessment for embryo development showed decreased rates of cleavage, morula and blastocyst in TMX group compared to control in vitro. In conclusion, these results suggest that ROS induced by TMX results in dysfunction of mitochondria and apoptosis, which block bovine oocytes to MI stage, trap them at AI/TI stage and trigger disordered chromosomes and spindle at MII stage. Additionally, MII oocytes with poor qualities result from TMX lose abilities to cleavage and develop to be morulae and blastocysts.
Fast Thresholding Based on Improved Minimum Cross Entropy
Yong-Liang Zhang,Wen Zhang,Gang Xiao,Jia-Fa Mao,Shan-Shan Huang,Xiao-Wei Zheng 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
Image segmentation is an important and classic problem in image processing and computer vision. Thresholding is applied to many fields, because of its less computation and stable performance. The key of thresholding method is to determine the adaptive threshold. In order to segment biological image effectively, a new adaptive thresholding method is proposed. First, two dimension minimum entropy is computed based on gray-gradient co-occurrence matrix; and then the genetic algorithm is applied to encode the two-dimension threshold vector; Finally, the optimum threshold is calculated based on fitness function and uniformity measurement(UM). Experimental results show that this method has three advantages: 1) improve computational efficiency so that it can run in real time; 2) retain more object and edge information so that it can meet the practical requirement; 3) robust to the uneven distribution of light.
Zheng, You-Bing,Zhao, Wei,Liu, Bing,Lu, Li-Gong,He, Xu,Huang, Jian-Wen,Li, Yong,Hu, Bao-Shan Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.9
Background and Aim: Increasing evidence correlates the presence of systemic inflammation with poor survival in patients with hepatocellular carcinoma (HCC). The aim of this study was to investigate the prognostic significance of the blood neutrophil-to-lymphocyte ratio (NLR) in patients with advanced HCC who received sorafenib monotherapy. Methods: A total of sixty-five patients with advanced HCC, not eligible for locoregional therapy, treated with sorafenib were enrolled. Potential prognostic factors such as age, gender, tumoral characteristics, performance status and NLR were analyzed. Results: Median OS and TTP for the entire cohort were 10.0 months (95%CI, 7.6-12.3 months) and 4.5 months (95% CI, 4.0-4.9 months). The mean NLR at baseline was 2.89. The median OS of patients with a high NLR (>4) was 6.5 months (95%CI, 5.2-7.7 months) compared with 12.5 months (95%CI, 9.9-15.0) for patients with a normal NLR (${\leq}4$) (P=0.01). Age ${\leq}65$, NLR>4, extrahepatic metastases and vascular invasion were all predictors of poorer overall survival. Multivariate analysis showed that NLR > 4, vascular invasion and extrahepatic metastases were independent predictors of poorer overall survival. The median TTP of patients with a high NLR was 2.5 months (95%CI, 1.4-3.6 months) compared with 4.5 months (95%CI, 3.9-5.1 months) for patients with a normal NLR (P=0.012). Conclusions: High baseline NLR was associated with worse OS and TTP for patients with advanced HCC treated with sorafenib.
MgO nanosheets with N-doped carbon coating for the efficient visible-light photocatalysis
Xiaogang Zheng,Ke Wang,Zhiping Huang,Yong Liu,Jing Wen,Hao Peng 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.76 No.-
MgO nanosheets with N-doped carbon coating (MgO@N-C) were fabricated for the enhancedphotocatalytic degradation of dyes (methylene blue, methyl violet, and Rhodamine B) and antibiotics(ciprofloxacin and tetracycline hydrochloride) in visible light region. The effects of N-doping content,reactant concentration, pH value, and inorganic ions on the photocatalytic performance in degradation ofmethylene blue were investigated in this work. Narrow band gap energy and heterojunction interfaceendowed the extended light-harvesting capacity to visible light region and the efficient charge transfer,leading to the excellent photocatalytic activity and durability of MgO@N-C-3 with N-doping content of 1.52%.
A miR-155–Peli1–c-Rel pathway controls the generation and function of T follicular helper cells
Liu, Wen-Hsien,Kang, Seung Goo,Huang, Zhe,Wu, Cheng-Jang,Jin, Hyun Yong,Maine, Christian J.,Liu, Yi,Shepherd, Jovan,Sabouri-Ghomi, Mohsen,Gonzalez-Martin, Alicia,Xu, Shunbin,Hoffmann, Alexander,Zheng, The Rockefeller University Press 2016 The Journal of experimental medicine Vol.213 No.9
<P>MicroRNA (miRNA) deficiency impairs the generation of T follicular helper (Tfh) cells, but the contribution of individual miRNAs to this phenotype remains poorly understood. In this study, we performed deep sequencing analysis of miRNAs expressed in Tfh cells and identified a five-miRNA signature. Analyses of mutant mice deficient of these miRNAs revealed that miR-22 and miR-183/96/182 are dispensable, but miR-155 is essential for the generation and function of Tfh cells. miR-155 deficiency led to decreased proliferation specifically at the late stage of Tfh cell differentiation and reduced CD40 ligand (CD40L) expression on antigen-specific CD4<SUP>+</SUP> T cells. Mechanistically, miR-155 repressed the expression of Peli1, a ubiquitin ligase that promotes the degradation of the NF-κB family transcription factor c-Rel, which controls cellular proliferation and CD40L expression. Therefore, our study identifies a novel miR-155–Peli1–c-Rel pathway that specifically regulates Tfh cell generation and function.</P>
Yaru Sun,Wenli Wang,Lan-yong Zhao,Chengshu Zheng,Fangfang Ma 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.5
Rosa rugosa ‘Shanxian’, a local variety of rose in Shandong Province, was studied for its aroma characteristics, includingchanges in aroma components and diff erential expression of aroma-related genes during fl owering. The volatiles emitted fromfl owers were collected by headspace solid-phase microextraction and analyzed by gas chromatography–mass spectrometry atthe budding stage, the early, half and full opening stages, and the withering stage. Sixty-six compounds were identifi ed, andthe full opening stage contained the highest level of every single aroma component compared with the other four stages. Themajor constituents of R. rugosa ‘Shanxian’ were alcohols, esters, ketones, aldehydes, phenols, and terpenes, with alcoholsbeing the most abundant. The aroma of R. rugosa ‘Shanxian’ was mainly characterized by rich fruit aromas, fl oral aromas, andsoft plant aromas. RrAAT , RrDXR , and RrDXS genes played a key role in monoterpene biosynthesis in R. rugosa ‘Shanxian’. The temporal and spatial expression of RrAAT , RrDXR , and RrDXS were measured at diff erent fl ower developmental stages. Among the three genes, the overall expression level of RrAAT was signifi cantly higher than that of RrDXR and RrDXS andwas associated with the accumulation of acetate esters in R. rugosa , which could be used as an important candidate gene forrose metabolism. Taken together, our results demonstrated that R. rugosa ‘Shanxian’ has better aromatic characteristics thanR. rugosa ‘Fenghua’. With a particularly prominent aroma that is strong and sweet, ‘Shanxian’ should be further investigatedas a valuable breeding material that could be used to enhance genetic diversity and develop new rose varieties.