Variable step adaptive kurtogram method based on empirical wavelet transform for rolling bearing fault diagnosis

Keqin Zhao,Feng Cheng,Wei-Xi Ji 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

Envelope analysis is one of the most effective methods in rolling element bearing diagnostics, but finding an optomal frequency band (OFB) has been a challenge for a long time. In this study, a variable-step adaptive kurtogram (VSAK) method based on empirical wavelet transform (EWT) was proposed to select the OFB and apply it in fault detection of rolling element bearings. The VSAK method mainly contains signal reconstruction based on EWT and detection of the appropriate demodulation frequency band based on RK. A new weighted kurtosis-RK was applied in this VSAK method to reduce the influence of high gaussian noise. According to simulation and experimental studies, the results showed that, VSAK was superior over those traditional methods, such as FK and autogram, for the diagnosis of rolling element bearing. It was also concluded that, the sum of amplitude corresponding to the first five fault harmonic frequencies based on VSAK was larger than the sum of amplitude based on FK as well as autogram method.

A Lectin Receptor Kinase Positively Regulates ABA Response During Seed Germination and Is Involved in Salt and Osmotic Stress Response

Keqin Deng,Qiming Wang,Jianxin Zeng,Xinhong Guo,Xiaoying Zhao,Dongying Tang,Xuanming Liu 한국식물학회 2009 Journal of Plant Biology Vol.52 No.6

Lectin receptor-like kinases (LecRK) are widespread in higher plants; however, little is known about their physiological roles. In this study, At1g70130 (designated LecRK-b2), an Arabidopsis LecRK gene, has been investigated. LecRK-b2 was predominantly expressed during seed germination, and its expression was ceased following germination. The expression of LecRK-b2 was induced by abscisic acid (ABA), salt, and osmotic stress. LecRK-b2 lossof- function mutation slightly reduced the ABA sensitivity during seed germination, and this reduced sensitivity was demonstrated not due to lower ABA accumulation level in the seeds. Dual-luciferase transient expression assay confirmed that the transcription factor ABSCISIC ACID INSENSITIVE3 (ABI3) could activate the luciferase under driving of LecRK-b2 promoter. LecRK-b2 transcription level was found to be down-regulated in abi3 during seed germination. Furthermore, LecRK-b2 loss-of-function mutation reduced the salt and osmotic sensitivity during early development stage of Arabidopsis. Taken together, these results suggest that LecRK-b2 functions as a positive regulator of the ABA response during the seed germination and is involved in salt and osmotic stress response in the early development stage.

Automatic bearing diagnosis based on improved empirical wavelet decomposition and nonparametric test

Hongyan Jiang,Keqin Zhao,Lifei Chen,Dianjun Fang,Feng Cheng,Yong Chen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

The 1/3-binary tree structure bandwidth is fixed, while the bands containing fault information sometimes do not fall equally in the fixed structure. To solve this problem, it is proposed to utilize the power spectrum to replace the Fourier spectrum, and to reconstruct the signal based on the scale space representation for the empirical wavelet decomposition. The fluctuation characteristics of the power spectrum frequency components and the energy distribution within frequency bands are taken full advantage of in this method. A new size parameter updating mechanism is employed to accelerate the signal reconstruction process. At the same time, it is thought that fault frequency is affected by the factor of slippage phenomena in order to realize a self-running diagnosis of bearing failure, and the occurring probability of the bearing fault is introduced to transform the envelope spectrum into a scalar indicator. As a result, without human intervention, the whole failure diagnosis process of the rolling bearing can be achieved by the manner of nonparametric testing. Simulation signal analysis results and experimental analysis results demonstrate the effectiveness and superiority of the proposed method.

Effect of MoS2 on Iron‑Based Friction Material Prepared Directly from Vanadium‑Bearing Titanomagnetite Concentrates

Yanyan Zhang,Keqin Feng,Yue Shui 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.7

The iron-based friction material was prepared directly from vanadium-bearing titanomagnetite concentrates by in situ selectivecarbothermic reactions and sintering process. This paper studies the effects of MoS2addition (1–4 wt%) on the microstructureand properties of iron-based friction material. The results show that the addition of MoS2greatly improves themicrostructure and properties of the material. During the sintering process, MoS2reacts with Fe to produce new lubricatingphase FeS and Mo which is dissolved in the Fe matrix. Appropriate amounts of FeS and Mo promote the sintering densification,which improves the microstructure by reducing the number of pores, as well as making the hard particles and graphitedistribute evenly. In addition, Mo could facilitate the formation of lamellar pearlite. As a result, the relative density, hardnessand tribological properties are significantly enhanced. Particularly, the friction coefficient decreases from 0.55 to 0.36–0.48and the wear rate decreases from 1.899 × 10−7 to 0.673 × 10−7–1.653 × 10−7 cm3/J when MoS2is added. However, excessiveMoS2deteriorates both the microstructure and properties of the material. The material containing 2 wt% MoS2representsthe optimum properties.

Working Conditions on the Afterglow Characteristics of Rare-earth Luminous Fibers

Xuefeng Guo,Keqin Zhang,Hongwei Zhang,Mingqiao Ge 한국섬유공학회 2018 Fibers and polymers Vol.19 No.3

To test and clarify the stability of afterglow performance of luminescent fibers can accelerate the step of the commercialized application on luminescent textiles. This work investigated the possible effects of a number of working conditions on the afterglow characteristics of luminous fibers. The fibers in our studies did not show any significant change in their afterglow brightness and duration after storage for 12 months under conditions of constant temperature and humidity, after 5 hours of light exposure, or soaking in water for 4 hours. The insignificant decay appears to follow the same mechanism. Thermal perturbation seemed to cause some changes to the initial brightness and decay time with the best performance being observed at about 80 oC. Moreover, contact with acid or base for 5 minutes only resulted in slight reduction of the afterglow brightness. Our studies thus indicate a high degree of stability of the afterglow performance of the luminous fibers used.

Ginseng polysaccharides: Potential antitumor agents

Ruizhi Tao,Keqin Lu,Gangfan Zong(강사),Yawen Xia,Hongkuan Han,Yang Zhao,Zhonghong Wei,Yin Lu 고려인삼학회 2023 Journal of Ginseng Research Vol.47 No.1

ELECTRICAL TRANSPORT PROPERTIES OF SINGLE-WALLED CARBON NANOTUBE BUNDLES TREATED WITH BORIC ACID

DALE HITCHCOCK,KEQIN YANG,JIAN HE,APPARAO M. RAO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.4

Electric-arc-synthesized single-walled carbon nanotube (SWNT) bundles were sonicated in boric acid, dried and sintered under vacuum at 1200°C using a spark plasma sintering process. The nominal boric acid concentrations were 0%, 2.5%, 5%, 7.5%, 12.5% and 15%. This resulted in a nonmonotonic variation of carrier concentration in the resulting samples. The 7.5% boric acid treated sample showed the least magnitude and weakest temperature-dependence for the thermopower with a distinct phonon-drag peak that was absent in the other samples. These results are discussed within the framework of the doping-induced shift of the Fermi level and changes in the electron–phonon coupling.

A Defect in Zinc Finger Protein Double B-box 1a (DBB1a) Causes Abnormal Floral Development in Arabidopsis

Qiming Wang,Xiaoju Tu,Keqin Deng,Jianxin Zeng,Xiaoying Zhao,Dongying Tang,Xuanming Liu 한국식물학회 2009 Journal of Plant Biology Vol.52 No.6

The double B-box (DBB) type zinc finger protein has thus far been shown to be involved in photomorphegenesis in Arabidopsis thaliana. Here, we show that DBB1a is expressed in the embryo, cytolden, and flower. Misexpression of DBB1a in mutant plants resulted in abnormal numbers and patterns of floral organs. We further show that DBB1a could regulate expression of several floral homeotic genes, including APETALA 2, APETALA 3, PISTILLATA, and AGAMOUS. Interestingly, expression of the microRNA gene MiR172, which is involved in organ boundary establishment, was also misregulated in the dbb1a mutant plants. Our study identified a previously uncharacterized role of DDB1a in regulation of expression of floral homeotic genes and miR172, which is important for understanding of floral pattern formation.

Antibacterial metabolites from the Actinomycete Streptomyces sp. P294

Huining Su,Hongwei Shao,Keqin Zhang,Guohong Li 한국미생물학회 2016 The journal of microbiology Vol.54 No.2

The Actinomycete strain P294 was isolated from soil and identified as Streptomyces sp. based upon the results of 16S rRNA sequence analysis. Three compounds obtained from the solid fermentation products of this strain have been determined by 1D, 2D NMR and HRMS experiments. These compounds include two new compounds angumycinones C (1) and D (2), and the known compound X-14881 E (3). All compounds were assayed for antibacterial and nematicidal activity. The results showed the three compounds had different degrees of inhibitory activity against several target bacteria but no significant toxicity against the nematode Caenorhabditis elegans.

Laparoscopic Sacrocolpopexy Plus Colporrhaphy With an Small Intestine Submucosa Graft Versus Total Pelvic Floor Reconstruction for Advanced Prolapse: A Retrospective Cohort Study

Junyan Wang,Xiaojuan Wang,Keqin Hua,Yisong Chen 대한배뇨장애요실금학회 2019 International Neurourology Journal Vol.23 No.2

Purpose: Transvaginal mesh (TVM) results in a greater anatomic cure but more complications. We aimed to compare laparoscopic sacrocolpopexy (LSC) plus colporrhaphy with the small intestine submucosa (SIS) graft versus TVM for advanced pelvic organ prolapse (POP). Methods: Patients with advanced POP who underwent LSC plus colporrhaphy with the SIS graft or TVM at a center between September 2015 and November 2016 were studied. Anatomical outcomes were evaluated using POP quantification. Functional outcomes related to POP and sexual life were evaluated using the Pelvic Floor Distress Inventory (PFDI-20) and the Pelvic Organ Prolapse/Urinary Incontinence Sexual Function Questionnaire (PISQ-12). Data regarding surgical procedures and patient demographic variables were recorded. Chi-square and Student t -tests were used for 2 independent samples. Results: A total of 76 patients were enrolled in this study with 26 patients in the LSC plus colporrhaphy with the SIS graft group (group A) and 50 patients with TVM group (group B). All patients in both groups demonstrated significant improvement in anatomical outcomes (P<0.05) after surgery. PFDI-20 scores were significantly improved 12 months after operation in both groups (P<0.001). PISQ-12 scores were significantly improved in patients after surgery, especially patients in group A (P<0.001). Mesh exposure occurred in both groups as follows: 8 patients (30.7%) in group A and 5 patients (10%) in group B. Conclusions: Even though both surgeries showed excellent results for subjective and objective outcomes, the use of an SIS graft might increase the exposure of polypropylene mesh. We do not recommend LSC plus colporrhaphy with the SIS graft for advanced multiple-compartments prolapse.