Simplified Rotor and Stator Resistance Estimation Method Based on Direct Rotor Flux Identification

Mingyu Wang,Dafang Wang,Guanglin Dong,Hui Wei,Xiu Liang,Zexu Xu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

Since parameter mismatch seriously impacts the efficiency and stability of induction motor drives, it is important to accurately estimate the rotor and stator resistance. This paper introduces a method to directly calculate the rotor flux that is independent of stator and rotor resistance and electrical angle. It is based on obtaining the rotor and stator resistance using the model reference adaptive system (MRAS) method. The method has a lower computation burden and less adaptation time when compared with other rotor resistance estimation methods. This paper builds three coordinate frames to analyze the rotor flux error and rotor resistance error. A number of implementation issues are also considered.

Selective release of less defective graphene during sliding of an incompletely reduced graphene oxide coating on steel

Xu, Shusheng,Liu, Yuzhen,Gao, Mingyu,Kang, Kyeong-Hee,Kim, Chang-Lae,Kim, Dae-Eun Elsevier 2018 Carbon Vol.134 No.-

<P><B>Abstract</B></P> <P>Recently, graphene has been gaining a lot of attention as a coating material that can be effectively utilized in reducing friction and wear of sliding components. In order to fully exploit the lubricious properties of graphene, the variation in the structure of the coating as sliding proceeds against a counter surface needs to be understood clearly. In this study, the structural evolution during sliding of an incompletely reduced graphene oxide (rGO) coating deposited on the 304 stainless steel by an electrodynamic spraying process was investigated. Experimental results showed that this coating possessed a low friction coefficient, below 0.05, under either low humidity air or dry N<SUB>2</SUB> gas condition. The micro-Raman and XPS analyses systematically revealed that less defective graphene structure was selectively released at the center region of the wear track. It was determined that the redistribution of graphene with different structures within the wear track was induced by frictional interaction at the sliding interface. Furthermore, it was determined that the degree of release of less defective graphene structure was proportional to both the applied normal force and sliding cycles.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Superior lubrication of dense/porous-coupled nanoscale C/WS₂ multilayer coating on ductile substrate

Xu, Shusheng,Liu, Yuzhen,Gao, Mingyu,Kang, Kyeong-Hee,Shin, Dong-Gap,Kim, Dae-Eun Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.476 No.-

<P><B>Abstract</B></P> <P>Sputtered carbon material has been receiving much attention as a solid lubricant coating owing to its high hardness and low coefficient of friction. However, its relatively low wear resistance performance when applied on a ductile substrate has limited its use in certain applications. In this work, a porous WS<SUB>2</SUB> sublayer was introduced to the sputtered carbon-based nanoscale multilayer coating to improve its tribological properties. The microstructural, mechanical and tribological properties of the nanoscale C/WS<SUB>2</SUB> multilayer coating were systematically investigated using various analytical techniques. Through structural optimization, a durable coating with excellent wear resistance and low frictional performances could be attained for a ductile steel substrate. The excellent toughness allowed the coating to deform with the ductile substrate without fracturing during contact sliding process. Furthermore, the first self-destruction and then recombination behaviors of dense/porous-coupled nanoscale multilayer coating as well as the selective release of carbon component to the contact interface driven by the frictional interaction aided in maintaining low friction. As a result, the nanoscale multilayer coating showed approximately 100-fold greater wear resistance than that of pure hard carbon coating on a ductile steel substrate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hard/soft-coupled nanoscale C/WS<SUB>2</SUB> multilayer coating was constructed by sputtering. </LI> <LI> The multilayer coating exhibited excellent synchronized deformation with the ductile steel substrate. </LI> <LI> Multilayer coating on ductile steel showed 100-fold longer wear life than that of a stiff C coating. </LI> <LI> The rearranged coating on the formed deep wear track resulted in improved lubrication performance. </LI> <LI> That provided a novel way to develop lubricant protection layer on ductile material surface </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Quercetin in a Lotus Leaves Extract May be Responsible for Antibacterial Activity

Mingyu Li,Zhuting Xu 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.5

In the course of a search for chemotherapeutic agents inhibiting suspected peridontitis bacteria, extracted and purified substances from lotus leaf were identified by antimicrobial activity tests with use of the broth micro-dilution methods on 96-microwell plate. The antimicrobial activity of extracts was tested against five microorganisms, namely: Actinobacillus actinomycetemcomitans Y4, Actinomyces viscosus 19246, Porphyromonas gingivalis 33277, Fusobacterium nucleatum 25586, and Actinomyces naeslundii wvl 45. The most active antimicrobial extract was subjected to spectroscopic analysis using UV, mass spectrometry, and by 1H, 13C-, nuclear magnetic resonance spectroscopy. Our data showed that the minimum inhibitory concentrations of the most active extract were 0.625, 1.25, 1.25, 0.625 and 2.5 mg/mL for A. actinomycetemcomitans, A. viscosus, P. gingivalis, F. nucleatum, and A. naeslundii, respectively. The component that had a greatest antimicrobial activity was determined to be quercetin. Thus, we conclude that quercetin extracted from lotus leaves may be a potential antibacterial agent for periodontitis

Hyperspectral Image Unmixing for Classification and Recognition : An Overview

Mingyu Nie,Zhi Liu,Hui Xu,Xiaoyan Xiao,Fangqi Su,Jun Chang,Xiaomei Li 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.12

The limited resolution of image sensors and the complex diversity of nature, cause mixed pixel problems in hyperspectral technology. Such problems are common, and increase the complexity of hyperspectral image processing. Hyperspectral unmixing is crucial for hyperspectral image classification and recognition. In unmixing, the image signatures are represented as a linear combination of the basic materials. Unmixing is the process of decomposing a mixed pixel into constituent materials, and calculating the corresponding fractional abundance. If pure materials (end members) are present in an image, unmixing can be divided into two steps, namely, end member extraction and abundance decomposition. On the other hand, if there is no pure material, researchers have devised and investigated unsupervised and semi-supervised spectral unmixing technology. This article presents an overview of the state-of-the-art methods of hyperspectral unmixing and their extensions.

Quercetin in a Lotus Leaves Extract May be Responsible for Antibacterial Activity

Li, Mingyu,Xu, Zhuting 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.5

In the course of a search for chemotherapeutic agents inhibiting suspected peridontitis bacteria, extracted and purified substances from lotus leaf were identified by antimicrobial activity tests with use of the broth micro-dilution methods on 96-microwell plate. The antimicrobial activity of extracts was tested against five microorganisms, namely: Actinobacillus actinomycetemcomitans Y4, Actinomyces viscosus 19246, Porphyromonas gingivalis 33277, Fusobacterium nucleatum 25586, and Actinomyces naeslundii wvl 45. The most active antimicrobial extract was subjected to spectroscopic analysis using UV, mass spectrometry, and by $^1H$, $^{13}C-$, nuclear magnetic resonance spectroscopy. Our data showed that the minimum inhibitory concentrations of the most active extract were 0.625, 1.25, 1.25, 0.625 and 2.5 mg/mL for A. actinomycetemcomitans, A. viscosus, P. gingivalis, F. nucleatum, and A. naeslundii, respectively. The component that had a greatest antimicrobial activity was determined to be quercetin. Thus, we conclude that quercetin extracted from lotus leaves may be a potential antibacterial agent for periodontitis.

Simplified Rotor and Stator Resistance Estimation Method Based on Direct Rotor Flux Identification

Wang, Mingyu,Wang, Dafang,Dong, Guanglin,Wei, Hui,Liang, Xiu,Xu, Zexu The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

Since parameter mismatch seriously impacts the efficiency and stability of induction motor drives, it is important to accurately estimate the rotor and stator resistance. This paper introduces a method to directly calculate the rotor flux that is independent of stator and rotor resistance and electrical angle. It is based on obtaining the rotor and stator resistance using the model reference adaptive system (MRAS) method. The method has a lower computation burden and less adaptation time when compared with other rotor resistance estimation methods. This paper builds three coordinate frames to analyze the rotor flux error and rotor resistance error. A number of implementation issues are also considered.

Renal-targeting peptide-microRNA nanocomplex for near IR imaging and therapy of renal ischemia/reperfusion injury

Yongtao Lin,Mingyue Zhao,Lin Bai,Hailun Li,Yong Xu,Xiang Li,Juan Xie,Yiyuan Zhang,Donghui Zheng 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.97 No.-

Renal ischemia-reperfusion injury (RI/R) is one of the main causes of acute renal injury and a commonclinical disease with high morbidity and mortality. It is of great significance to deliver microRNAs(miRNAs) to cells and in vivo to realize gene regulation and treatment of related diseases. In this study, wereported that the nanocomplex FMN-17 could realize both therapeutic and functional monitoringsimultaneously in vivo and in vitro. The nanocomplex comprised a cationic cell-penetrating peptidenona-arginine, a targeting ligand folic acid, a caspase-3 responsive moiety, and a Cy imaging moiety. Thenanocomplex FMN-17 has been shown to deliver miR-17-5p efficiently and selectively into HK-2 cells andtissues. Treatment of HK-2 cells with the nanocomplex significantly increased the miR-17-5p level andinhibited apoptosis, as evident by reducing the expression of active caspase-3 and reactive oxygenspecies. Uptake of FMN-17 in vivo alleviated renal tissue injury by histological assessment. In summary,we designed and synthesized a new miRNA delivery system with high transfection efficiency, goodtherapeutic effect, and near-infrared imaging in renal ischemia/reperfusion injury.

Effect of phosphorus deficiency on erythrocytic morphology and function in cows

Ziwei Zhang,Mingyu Bi,Jie Yang,Haidong Yao,Zhonghua Liu,Shiwen Xu 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.3

The aim of this study was to evaluate the influence of phosphorus (P) deficiency on the morphological and functional characteristics of erythrocytes in cows. Forty Holstein-Friesian dairy cows in mid-lactation were randomly divided into two groups of 20 each and were fed either a low-P diet (0.03% P/kg dry matter [DM]) or a control diet (0.36% P/kg DM). Red blood cell (RBC) indices results showed RBC and mean corpuscular hemoglobin decreased while mean corpuscular volume increased significantly (p < 0.05) in P-deficient cows. Erythrocyte morphology showed erythrocyte destruction in P-deficient cows. Erythrocytes’ functional characteristics results showed total bilirubin and indirect bilirubin concentrations and aspartate transaminase and alanine transaminase activity levels in the serum of P-deficient cows were significantly higher than those in control diet-fed cows. Activities of superoxide dismutase and glutathione peroxidase in erythrocytes were lower, while the malondialdehyde content was greater, in P-deficient cows than in control diet-fed cows. Na+/K+-ATPase and Mg2+-ATPase activities were lower in P-deficient cows than in control diet-fed cows; however, Ca2+-ATPase activity was not significantly different. The phospholipid composition of the erythrocyte membrane changed and membrane fluidity rigidified in P-deficient cows. The results indicate that P deficiency might impair erythrocyte integrity and functional characteristics in cows.

Effect of charge type of hydrogel on its dye adsorption capacity and kinetic study

Qiuyu Liang,Mingyu Yin,Shi Feng,Xu Xiang 한국고분자학회 2024 Macromolecular Research Vol.32 No.3

Hydrogel has a wide range of applications in many fields because of its good adsorption capacity. There are many factors affecting the adsorption performance of hydrogels, among which the charge of the gel itself is crucial. This work proposes a method to detect the amount of dye adsorbed by measuring the absorbance of hydrogels. Using this method, polyacrylamide (PAM) hydrogels with different charge types were prepared, and their adsorption performance on Congo red and methylene blue dyes was investigated to elucidate the relationship between the charge carried by the hydrogel itself and the adsorption performance. Experiments show that the adsorption capacity of hydrogel for dyes is closely related to its charge, that is, the hydrogel is more likely to adsorb dye molecules with an opposite charge to the hydrogel and the adsorption behavior conforms to the Freundlich isothermal adsorption model. Taking anionic hydrogel as an example, the adsorption kinetics of methylene blue on anionic hydrogel were further studied, and the kinetic model was in accordance with the pseudo-secondary kinetic model, suggesting that a pseudo-second-order kinetic model is more suitable for the adsorption behavior of anionic hydrogels for methylene blue dye. This work helps researchers better understand the role of the charge of hydrogel in the adsorption process and helps to design more targeted hydrogels.