Stray capacitances influences of various parallel primary windings in input‑series transformer‑integration flyback converters

Junjie Xie,Yichen Chang,Tao Meng 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.12

In this paper, the influences of stray capacitances are explored for various parallel arrangements of primary windings (PWs) in input-series transformer-integration (ISTI) flyback converters. On this basis, selecting the principle of the basic parallel PWs arrangements is clarified in the design process. First, the influences caused by the energy changes of stray capacitances are analyzed for PWs in ISTI converter. Based on this, the arrangements of single PWs and various parallel PWs are presented. Second, the energy influences of both the inner and inter-winding capacitances are analyzed and compared for two basic parallel PWs in an ISTI converter. In addition, selecting the principle of these PWs arrangements is summarized. Finally, four integrated transformers with various PW arrangements are designed, and experimental comparisons are implemented on a 1000 Vdc/48 W ISTI flyback converter. Through the obtained results, the validity of theoretical analysis is verified.

Efficient Multicast Routing on BCube-Based Data Centers

( Junjie Xie ),( Deke Guo ),( Jia Xu ),( Lailong Luo ),( Xiaoqiang Teng ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.12

Multicast group communication has many advantages in data centers and thus is widely used by many applications. It can efficiently reduce the network traffic and improve the application throughput. For the multicast application in data centers, an essential problem is how to find a minimal multicast tree, which has been proved to be NP-hard. In this paper, we propose an approximation tree-building method for the minimal multicast problem, named HD(Hamming Distance)-based multicast tree. Consider that many new network structures have been proposed for data centers. We choose three representative ones, including BCube, FBFLY, and HyperX, whose topological structures can be regarded as the generalized hypercube. Given a multicast group in BCube, the HD-based method can jointly schedule the path from each of receiver to the only sender among multiple disjoint paths; hence, it can quickly construct an efficient multicast tree with the low cost. The experimental results demonstrate that our method consumes less time to construct an efficient multicast tree, while considerably reduces the cost of the multicast tree compared to the representative methods. Our approach for BCube can also be adapted to other generalized hypercube network structures for data centers after minimal modifications.

Analysis of Switching Clamped Oscillations of SiC MOSFETs

Junji Ke,Zhibin Zhao,Zongkui Xie,Changjun Wei,Xiang Cui 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

SiC MOSFETs have been used to improve system efficiency in high frequency converters due to their extremely high switching speed. However, this can result in undesirable parasitic oscillations in practical systems. In this paper, models of the key components are introduced first. Then, theoretical formulas are derived to calculate the switching oscillation frequencies after full turn-on and turn-off in clamped inductive circuits. Analysis indicates that the turn-on oscillation frequency depends on the power loop parasitic inductance and parasitic capacitances of the freewheeling diode and load inductor. On the other hand, the turn-off oscillation frequency is found to be determined by the output parasitic capacitance of the SiC MOSFET and power loop parasitic inductance. Moreover, the shifting regularity of the turn-off maximum peak voltage with a varying switching speed is investigated on the basis of time domain simulation. The distortion of the turn-on current is theoretically analyzed. Finally, experimental results verifying the above calculations and analyses are presented.

Structural Design and Electrical Characteristics of Wearable and Flexible Stainless Steel/Polyester Fibre Mixture

Junjie Ou,Juan Xie,Yongtang Jia 한국섬유공학회 2021 Fibers and polymers Vol.22 No.3

The metallic fibres-based composite yarns have been increasingly used to make flexible, comfortable andwearable fabric sensors, which have advantages in monitoring human physical and physiological body characteristics. In ourprevious study, flexible and conductive blended yarns made from stainless steel (SS) fibres were fabricated into highlysensitive knitted fabric sensors. However, as the SS weight ratio increased (particularly the pure SS fibres-based yarn), yarnswere easily broken in knitting process. Here we made adjustments to the new series of composite yarns with similar absolutefineness (same diameters) rather than relative fineness (linear density). Not only the problem of yarn breakage has beensolved, it also retains the well-conductive (less than 70 Ω/cm) and flexible and wearable properties. A more important resultis that the varying probe span length makes little impact on these SS fibre mixtures’ values of percolation threshold (0.178based on weight ratio and 0.015 on volume fraction, respectively) and on critical exponents (about 1.3, according with theuniversal conductivity exponent in 2D conductive polymer composite system). The main reason may be on account of thesecomposite yarns having similar diameters (absolute fineness) and so aspect ratio.

Analysis of Switching Clamped Oscillations of SiC MOSFETs

Ke, Junji,Zhao, Zhibin,Xie, Zongkui,Wei, Changjun,Cui, Xiang The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

SiC MOSFETs have been used to improve system efficiency in high frequency converters due to their extremely high switching speed. However, this can result in undesirable parasitic oscillations in practical systems. In this paper, models of the key components are introduced first. Then, theoretical formulas are derived to calculate the switching oscillation frequencies after full turn-on and turn-off in clamped inductive circuits. Analysis indicates that the turn-on oscillation frequency depends on the power loop parasitic inductance and parasitic capacitances of the freewheeling diode and load inductor. On the other hand, the turn-off oscillation frequency is found to be determined by the output parasitic capacitance of the SiC MOSFET and power loop parasitic inductance. Moreover, the shifting regularity of the turn-off maximum peak voltage with a varying switching speed is investigated on the basis of time domain simulation. The distortion of the turn-on current is theoretically analyzed. Finally, experimental results verifying the above calculations and analyses are presented.

Synthesis and Characterization of Fluorescent Waterborne Polyurethane Based on 4'-p-N,N-Bis(2-hydroxyethyl)benzyl-3,3':6',2"-Terpyridine

Xixi Han,Can Tao,Zhiqian Xie,Junjie Bao,Yiping Huang,Gewen Xu 한국고분자학회 2017 폴리머 Vol.41 No.3

Cationic waterborne polyurethane fluorescent material based on 4"-p-N,N-bis(2-hydroxyethyl)benzyl-3,3":6",2""-terpyridine (TPPDA-CWPU) was synthesized. The structure was characterized by FTIR and UV-vis spectroscopy. The content of TPPDA in the fluorescent polyurethane was 6.3×10<SUP>-4</SUP> mg/mg and the grafting ratio was 33.87%. The number-averaged and weight-average molecular weights of TPPDA-CWPU were about 16060 and 27131 g·mol<SUP>-1</SUP>, respectively. The maximum absorption wavelength of TPPDA-CWPU was blue shifted ca. 6 nm compared to TPPDA. TPPDACWPU showed different fluorescence properties under different solid content. Compared with 20% solid content, the fluorescence intensity of 1% solid content increased by ten times. The quantum yield of TPPDA-CWPU was 0.3, which was four times higher than that of TPPDA. Moreover, TPPDA-CWPU was sensitive to acidic condition and there was the phenomenon of fluorescence quenching in the case of strong acidic conditions. It is believed that more applications will be possible in the pH-responsive polymer.

Identification and Characterization of Two New S-Adenosylmethionine- Dependent Methyltransferase Encoding Genes Suggested Their Involvement in Stipe Elongation of Flammulina velutipes

( Qianhui Huang ),( Irum Mukhtar ),( Yelin Zhang ),( Zhongyang Wei ),( Xing Han ),( Rongmei Huang ),( Junjie Yan ),( Baogui Xie ) 한국균학회 2019 Mycobiology Vol.47 No.4

Two new SAM-dependent methyltransferase encoding genes (fvsmt1 and fvsmt2) were identified from the genome of Flammulina velutipes. In order to make a comprehensive characterization of both genes, we performed in silico analysis of both genes and used qRT-PCR to reveal their expression patterns during the development of F. velutipes. There are 4 and 6 exons with total length of 693 and 978 bp in fvsmt2 and fvsmt1, respectively. The deduced proteins, i.e., FVSMT1 and FVSMT2 contained 325 and 230 amino acids with molecular weight 36297 and 24894 Da, respectively. Both proteins contained a SAM-dependent catalytic domain with signature motifs (I, p-I, II, and III) defining the SAM fold. SAM-dependent catalytic domain is located either in the middle or at the N-terminal of FVSMT2 and FVSMT1, respectively. Alignment and phylogenic analysis showed that FVSMT1 is a homolog to a protein- arginine omega-N-methyltransferase, while FVSMT2 is of cinnamoyl CoA O-methyltransferase type and predicted subcellular locations of these proteins are mitochondria and cytoplasm, respectively. qRT-PCR showed that fvsmt1 and fvsmt2 expression was regulated in different developmental stages. The maximum expression levels of fvsmt1 and fvsmt2 were observed in stipe elongation, while no difference was found in mycelium and pileus. These results positively demonstrate that both the methyltransferase encoding genes are involved in the stipe elongation of F. velutipes.

Identification and Expression Patterns of fvexpl1, an Expansin-Like Protein-Encoding Gene, Suggest an Auxiliary Role in the Stipe Morphogenesis of Flammulina velutipes

( Qianhui Huang ),( Xing Han ),( Irum Mukhtar ),( Lingling Gao ),( Rongmei Huang ),( Liping Fu ),( Junjie Yan ),( Yongxin Tao ),( Bingzhi Chen ),( Baogui Xie ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.4

Expansins are cell wall proteins that mediate cell wall loosening and promote specific tissue and organ morphogenesis in plants and in some microorganisms. Unlike plant expansins, the biological functions of fungal expansin-like proteins have rarely been discussed. In the present study, an expansin-like protein-encoding fvexpl1 gene, was identified from Flammulina velutipes by using local BLAST. It consisted of five exons with a total length of 822 bp. The deduced protein FVEXPL1 contained 274 amino acids with a predicted molecular mass and isoelectric point of 28,589 Da and pH 4.93, respectively. The first 19 amino acids from the N terminal are the signal peptide. Phylogenetic analysis and multiple protein alignment indicated FVEXPL1 was an expansin-like protein. The expression level of fvexpl1 gene in the stipe was significantly higher than that in the mycelia, primordia, and cap. However, the expression level of fvexpl1 gene was significantly higher in the fast elongation region of the stipe as compared with the slow elongation region. Expression analysis indicated that fvexpl1 gene might have an auxiliary role in the stipe morphogenesis of F. velutipes.

Distinct Transcriptional and Functional Differences of Lung Resident and Monocyte-Derived Alveolar Macrophages During the Recovery Period of Acute Lung Injury

Hou Fei,Wang Huan,Zheng Kun,Yang Wenting,Xiao Kun,Rong Zihan,Xiao Junjie,Li Jing,Cheng Baihe,Tang Li,Xie Lixin 대한면역학회 2023 Immune Network Vol.23 No.3

In acute lung injury, two subsets of lung macrophages exist in the alveoli: tissue-resident alveolar macrophages (AMs) and monocyte-derived alveolar macrophages (MDMs). However, it is unclear whether these 2 subsets of macrophages have different functions and characteristics during the recovery phase. RNA-sequencing of AMs and MDMs from the recovery period of LPS-induced lung injury mice revealed their differences in proliferation, cell death, phagocytosis, inflammation and tissue repair. Using flow cytometry, we found that AMs showed a higher ability to proliferate, whereas MDMs expressed a larger amount of cell death. We also compared the ability of phagocytosing apoptotic cells and activating adaptive immunity and found that AMs have a stronger ability to phagocytose, while MDMs are the cells that activate lymphocytes during the resolving phase. By testing surface markers, we found that MDMs were more prone to the M1 phenotype, but expressed a higher level of pro-repairing genes. Finally, analysis of a publicly available set of single-cell RNA-sequencing data on bronchoalveolar lavage cells from patients with SARS-CoV-2 infection validated the double-sided role of MDMs. Blockade of inflammatory MDM recruitment using CCR2−/− mice effectively attenuates lung injury. Therefore, AMs and MDMs exhibited large differences during recovery. AMs are long-lived M2-like tissue-resident macrophages that have a strong ability to proliferate and phagocytose. MDMs are a paradoxical group of macrophages that promote the repair of tissue damage despite being strongly pro-inflammatory early in infection, and they may undergo cell death as inflammation fades. Preventing the massive recruitment of inflammatory MDMs or promoting their transition to pro-repairing phenotype may be a new direction for the treatment of acute lung injury.