Model-based analysis and fault diagnosis of a compound planetary gear set with damaged sun gear

Guoyan Li,Xihui Liang,Fang-Yi Li 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.7

The vibration properties of compound planetary gears are more complicated than that of simple ones. This paper aims to investigate the fault properties of a compound planetary gear set in chipped sun gear conditions using model-based method. A three-dimensional lumped-parameter nonlinear dynamic model for the compound planetary gear set is established. This model considers the time-varying mesh stiffness (TVMS), the mesh phase relations, and gear chipping defects. The analytical equations are derived to quantify the TVMS reduction induced by the chipped gear based on the improved potential energy method. Further, the simulations are performed to demonstrate the fault features of sun gears with single or multiple chipped teeth in different gear stages. Moreover, the theoretical derivations are validated through the experimental signals analysis.

Effect of oxygen non-stoichiometry on magnetic and electrical transport properties of La0.67Sr0.33MnO3

Huo Guoyan,Su Qian,Li He,Li Zhenxing,Chang Yating 한국물리학회 2020 Current Applied Physics Vol.20 No.6

The effect of oxygen deficiency and oxygen excess on the magnetic and electrical transport properties of La0.67Sr0.33MnO3 has been investigated. The thermal and isothermal magnetization measurement results show that the Curie temperature and saturation magnetization of oxygen deficient sample (defined as A) are higher than those oxygen excess sample (defined as B). The electrical resistivity of A is lower than that of B in studied temperature range. The magnetoresistance (MR) of B is larger than that of A in the temperature range from 280 to 360 K, which agrees with the magnetic field needed full spin polarization at room temperature. The colossal MR (CMR) around transition temperature from ferromagnetic metal to paramagnetic insulator (TMI) for A is larger than that for B, which arises from assistance of stronger lattice deformation for A.

A Novel Vibration Model for Explanation of the Frequency Features in Multistage Wind Turbine Gearboxes Considering the Effects of Inter-stage Meshing Frequency Modulation

Yanyan Nie,Fangyi Li,Liming Wang,Jianfeng Li,Yanle Li,Mingshuai Sun,Mengyao Wang,Guoyan Li 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.1

As a kind of green energy, wind energy has become cost-competitive mainstream energy in the world. The gearbox is one of the most important and vulnerable components in the wind turbine (WT), which suffers a high failure rate and downtime. It is of great significance to the condition monitoring and fault diagnosis of the WT gearbox. However, in the multistage WT gearbox, the vibrations generated from different stages are coupled, which leads to a complex vibration spectral structure and brings difficulties in condition monitoring and fault diagnosis. Aiming to understand the vibration frequency features of multistage WT gearboxes, a novel phenomenological vibration model is established and the spectral structure is deduced by using the Fourier series analysis. In the vibration model, the phenomenon of inter-stage meshing frequency modulation (ISMFM) is considered, which is clearly proposed for the first time. The theoretical derivations are validated by both simulation and engineering tests using a 2.0 MW industrial WT gearbox. The results show that under healthy conditions, in addition to the meshing frequencies and their harmonics of each stage, there are also ISMFM sidebands in the vibration spectrum of the multistage WT gearbox, and the amplitude of the sidebands will change with the health status of the gearbox. The findings are not only applicable to the WT gearbox studied in this paper, but also to other similar multistage gearbox systems, which can provide a priori spectral structure for a multistage gear transmission system to assist its condition monitoring and fault diagnosis.

Bacillus subtilis Spore Surface Display Technology: A Review of Its Development and Applications

( Guoyan Zhang ),( Yingfeng An ),( Hossain M. Zabed ),( Qi Guo ),( Miaomiao Yang ),( Jiao Yuan ),( Wen Li ),( Wenjin Sun ),( Xianghui Qi ) 한국미생물 · 생명공학회 2019 Journal of microbiology and biotechnology Vol.29 No.2

Bacillus subtilis spore surface display (BSSD) technology is considered to be one of the most promising approaches for expressing heterologous proteins with high activity and stability. Currently, this technology is used for various purposes, such as the production of enzymes, oral vaccines, drugs and multimeric proteins, and the control of environmental pollution. This paper presents an overview of the latest developments in BSSD technology and its application in protein engineering. Finally, the major limitations of this technology and future directions for its research are discussed.

Analysis of queuing mine-cars affecting shaft station radon concentrations in Quzhou uranium mine, eastern China

홍창수,Guoyan Zhao,Xiangyang Li 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.3

Shaft stations of underground uranium mines in China are not only utilized as waiting space forloaded mine-cars queuing to be hoisted but also as the principal channel for fresh air taken to workingplaces. Therefore, assessment of how mine-car queuing processes affect shaft station radon concentrationwas carried out. Queuing network of mine-cars has been analyzed in an underground uraniummine, located in Quzhou, Zhejiang province of Eastern China. On the basis of mathematical analysis ofthe queue network, a MATLAB-based quasi-random number generating program utilizing Monte-Carlomethods was worked out. Extensive simulations were then implemented via MATALB operating on aDELL PC. Thereafter, theoretical calculations and field measurements of shaft station radon concentrationsfor several working conditions were performed. The queuing performance measures of interest,like average queuing length and waiting time, were found to be significantly affected by theutilization rate (positively correlated). However, even with respect to the “worst case”, the shaftstation radon concentration was always lower than 200 Bq/m3. The model predictions were comparedwith the measuring results, and a satisfactory agreement was noted. Under current working conditions,queuing-induced variations of shaft station radon concentration of the study mine are notremarkable.

Prenylated flavonoid fractions from Glycyrrhiza glabra alleviate insulin resistance in HepG2 cells by regulating the ERK/IRS-1 and PI3K/Akt signaling pathways

Defeng Li,Jinling Fan,Lin Du,Guoyan Ren 대한약학회 2024 Archives of Pharmacal Research Vol.47 No.2

Insulin resistance (IR) is a key factor in the pathogenesis of disrupted glucose metabolism. Although the extract of Glycyrrhizaglabra has shown signifi cant hypoglycemic activity, its bioactive components remain to be identifi ed, and theirmechanisms of action, especially on hepatocyte glucose metabolism, are yet to be explored. In the present study, the primarycompounds from Glycyrrhiza glabra [named prenylated fl avonoid fractions (PFFs)] have been identifi ed and their chemicalstructures have been elucidated. The therapeutic eff ects of PFFs extracted from G. glabra on glucose metabolism disordersand IR in high insulin-induced insulin-resistant HepG2 (IR-HepG2) cells have been determined. Glabridin (GLD) was usedas a control. The results indicated that, similar to GLD, PFFs increased glucose consumption, glucose uptake, and translocationof glucose transporter 4 to the plasma membrane in IR-HepG2 cells. In addition, they enhanced the activities ofglycogen synthase, glucokinase, and pyruvate kinase, while reducing the activities of phosphoenolpyruvate carboxykinaseand glucose-6-phosphatase. Furthermore, they activated the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt)pathway and suppressed the extracellular signal-regulated kinase/insulin receptor substrate-1 (ERK/IRS-1) pathway. Thesefi ndings suggest that, similar to GLD, PFFs can alleviate impaired glucose metabolism and alleviate IR in IR-HepG2 cells.

Pyramid-like CdS nanoparticles grown on porous TiO₂ monolith: An advanced photocatalyst for H₂ production

Du, Jimin,Wang, Huiming,Yang, Mengke,Li, Kaidi,Zhao, Lixin,Zhao, Guoyan,Li, Sujuan,Gu, Xiaolei,Zhou, Yalan,Wang, Le,Gao, Yating,Wang, Weimin,Kang, Dae Joon Pergamon Press 2017 Electrochimica Acta Vol. No.

<P><B>Abstract</B></P> <P>Efficient production of H<SUB>2</SUB> via solar-light-driven water splitting by a semiconductor-based photocatalyst without noble metals is crucial owing to increasingly severe global energy and environmental issues. However, many challenges, including the low efficiency of H<SUB>2</SUB> evolution, low solar light absorption, excited electron–hole pair recombination, and slow transport of photoexcited carriers, must be resolved to enhance the H<SUB>2</SUB> photoproduction efficiency and photocatalyst stability. Here, a two-step method is used to synthesize advanced H<SUB>2</SUB>-generating photocatalysts consisting of pyramid-like CdS nanoparticles grown on a porous TiO<SUB>2</SUB> monolith, which show promising photocatalytic activity for the hydrogen evolution reaction. Furthermore, the stability of the photocatalysts is examined through long-term tests to verify their good durability. Without noble metals as cocatalysts, the photocatalyst can reach a high H<SUB>2</SUB> production rate of 1048.7μmolh<SUP>−1</SUP> g<SUP>−1</SUP> under UV–vis irradiation when the ratio of the CdS nanoparticles to TiO<SUB>2</SUB> is 5mol%. This unusual photocatalytic activity arises from the wide-region light adsorption due to the narrow band gap of CdS, effective separation of electrons and holes due to conduction band alignment at the CdS–TiO<SUB>2</SUB> interface, and favorable reaction sites resulting from the porous structure.</P>

Induction of Apoptosis in Glioma Cells and Upregulation of Fas Expression Using the Human Interferon-β Gene

Guo, Yan,Wang, Gan,Gao, Wen-Wei,Cheng, Shi-Wen,Wang, Ren,Ju, Shi-Ming,Cao, He-Li,Tian, Heng-Li Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.6

We investigated whether IFN-${\beta}$ inhibits the growth of human malignant glioma and induces glioma cell apoptosis using the human IFN-${\beta}$ gene transfected into glioma cells. A eukaryonic expression vector ($pSV2IFN{\beta}$) for IFN-${\beta}$ was transfected into the glioma cell line SHG44 using liposome transfection. Stable transfection and IFN-${\beta}$ expression were confirmed using an enzyme-linked immunosorbent assay (ELISA). Cell apoptosis was also assessed by Hoechst staining and electron microscopy. In vivo experiments were used to establish a SHG44 glioma model in nude mice. Liposomes containing the human IFN-${\beta}$ gene were injected into the SHG44 glioma of nude mice to observe glioma growth and calculate tumor size. Fas expression was evaluated using immunohistochemistry. The IFN-${\beta}$ gene was successfully transfected and expressed in the SHG44 glioma cells in vitro. A significant difference in the number of apoptotic cells was observed between transfected and non-transfected cells. Glioma growth in nude mice was inhibited in vivo, with significant induction of apoptosis. Fas expression was also elevated. The IFN-${\beta}$ gene induces apoptosis in glioma cells, possibly through upregulation of Fas. The IFN-${\beta}$ gene modulation in the Fas pathway and apoptosis in glioma cells may be important for the treatment of gliomas.