Fault diagnosis of rolling bearing using a refined composite multiscale weighted permutation entropy

Yongjian Li,Qiuming Gao,Peng Li,Jihua Liu,Yingmou Zhu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.5

The health status information of rolling bearings is often contained in vibration signals, but it is difficult to detect bearing defects directly through vibration signals. To effectively extract the key feature information hidden in the original signal, this paper proposes the refined composite multiscale weighted permutation entropy (RCMWPE) method to efficiently characterize the operating state of the bearing. The proposed method focuses on two aspects:the improved version reduces the dependence of entropy on the length of the original time series, and the error caused by considering the amplitude information is suppressed. The performance of the proposed method is evaluated by synthetic signals and real bearing data, and compared with other traditional methods. By analyzing bearing signals of different fault types and different degrees of damage, it is verified that the proposed method can obtain more stable and reliable results and achieve higher fault diagnosis accuracy.

Refined composite multiscale fuzzy entropy: Localized defect detection of rolling element bearing

Yongjian Li,Bingrong Miao,Weihua Zhang,Peng Chen,Jihua Liu,Xiaoliang Jiang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

We proposed an appealing method based on refined composite multiscale fuzzy entropy (RCMFE), infinite feature selection (Inf-FS) algorithm, and support vector machine (SVM) for implementing localized defect detection to keep the downtime and extended damage caused by incipient failure of bearing at a minimum. As a useful approach, multiscale fuzzy entropy (MFE) was utilized to measure the complexity and dynamic changes of signals. However, an inaccurate entropy value would be yielded with the increase of scale factor. Here, as an improvement version of MFE, the RCMFE was proposed to address the shortcomings in the case of short time series. For this novel method, we conducted a full investigation of the effects and robustness by comparing the proposed method with two other entropybased approaches using synthetic signals and real data. Results indicate that the proposed algorithm outperforms the other approaches in terms of reliability and stability. The RCMFE values of bearing signals from one healthy condition and seven fault states are calculated as diagnostic information. Moreover, an intelligent fault identification method was constructed by combining the Inf-FS algorithm and SVM classifier. Experimental results show the usefulness of the proposed strategy.

A Fast Adjustment Method of Magnetically Controlled Reactor with Multi-taps

Mengsen Liu,Yongjian Li,Hezhe Gao,Xuehai Gong Korean Magnetics Society 2018 Journal of Magnetics Vol.23 No.4

Magnetically controlled reactor (MCR) can compensate the capacitive reactive power generated by transmission line and enhance the stability of power supply, which is widely used in ultrahigh-voltage (UHV) power systems. In this paper, a novel structure for MCR with multi-taps is proposed. The MCR with multi-taps can switch its taps based on operation condition. The higher tap ratio is used to adjust the reactive power, and the lower tap ratio is fit for the stable grid. A switching algorithm is designed to make it work harmoniously and flexibly. For the adjustment of reactive power, this novel structure can perform better in regulated time without using higher tap ratios in practical operation, compared with the traditional structures.

Temperature influences the toxicity, behavioral, and physiology response of chlorfenapyr, fipronil, imidacloprid, and indoxacarb to Reticulitermes flaviceps

Han Hui,Liu Yu,Yang Shimeng,Xue Haozhe,Zhang Dayu,Xie Yongjian 한국응용곤충학회 2024 Journal of Asia-Pacific Entomology Vol.27 No.2

A comprehensive understanding of the interaction between pesticides and climate change is critical to the safety of pesticide applications. Many insecticides are actually more toxic at higher temperatures. However, little is currently known about the effect of temperature on the toxicity of chemicals. In order to fill this knowledge gap and improve our understanding of the mechanisms of temperature effects, the present study investigated the toxic, physiological, and behavioral effects of four insecticides, chlorfenapyr, fipronil, imidacloprid, and indoxacarb, on subterranean termites, Reticulitermes flaviceps at different temperatures (24 to 32 ◦ C). The results show that the sensitivity of R. flaviceps to chrofenapyr (LC 50 = 8.67–152.49 mg/L), fipronil (LC 50 = 10.14–36.84 mg/L), imidacloprid (LC 50 = 184.27–326.47 mg/L) and indoxacarb (LC 50 = 12.23–46.23 mg/L) substantially increased when the temperature alters from 24 to 32 ◦ C. Additionally, the activities of three detoxification en zymes [glutathione S-transferases (GSTs), carboxylesterase (CarE), and cytochrome P450 (P450)] of R. flaviceps were also measured of four insecticide at various temperatures. Correlation analysis reveals that changes in GSTs CarE and P450 activities of R. flaviceps are closely related to their sensitivity to chlorfenapyr, fipronil, imida cloprid, and indoxacarb. Meanwhile, the speed of action (LT 50 value) of four insecticides is positively affected by temperature. In addition, intoxication, ataxia, and moribundity behaviors were observed in most concentrations and temperature combinations for chlorfenapyr, fipronil, and imidacloprid–exposed termite. The findings of our research emphasize that in the context of global climate change, the development and application of pesticides should consider the temperature dimension.

Experimental investigation on strength of CFRST composite truss girder

Yinping Ma,Yongjian Liu,Kun Wang 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.48 No.6

Concrete filled rectangular steel tubular (CFRST) composite truss girder is composed of the CFRST truss and concrete slab. The failure mechanism of the girder was different under bending and shear failure modes. The bending and shear strength of the girder were investigated experimentally. The influences of composite effect and shear to span ratio on failure modes of the girder was studied. Results indicated that the top chord and the joint of the truss were strengthened by the composited effect. The failure modes of the specimens were changed from the joint on top chord to the bottom chord. However, the composite effect had limited effect on the failure modes of the girder with small shear to span ratio. The concrete slab and top chord can be regarded as the composite top chord. In this case, the axial force distribution of the girder was close to the pinjointed truss model. An approach of strength prediction was proposed which can take the composite effect and shear to span ratio into account. The approach gave accurate predictions on the strength of CFRST composite truss girder under different bending and shear failure modes.

Analysis and Research on Space Vector Over-modulation Strategy of Indirect Matrix Converter

Wenshen Wang,Shanhu Li,Xu Liu,Yongjian Li,Yiping Liu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

In this paper, based on the characteristics of six space vector modulation methods, a variety of Space Vector Over-modulation strategies with voltage transfer ratio of 1.05 for indirect matrix converter is proposed. Firstly, the six space vector modulation methods are combined by adjusting the phase of the input current vector and the amplitude and phase of the output voltage vector. Secondly, the limit input current and output voltage vector characteristics, the limit fundamental voltage amplitude and the main low-frequency harmonic components of the input and output under the six modulation methods are analyzed in detail. According to the limit characteristics of the six modulation methods and the principle of limit vector superposition, multiple space vector over-modulation strategies based on single-mode, doublemode and multi-mode are proposed. Finally, the characteristics of the six space vector modulation methods are verified by experiments.

Tailored therapy and long-term surveillance of malignant germ cell tumors in the female genital system: 10-year experience

Qianying Zhao,Jiaxin Yang,Dongyan Cao,Jiangna Han,Kaifeng Xu,Yongjian Liu,Keng Shen 대한부인종양학회 2016 Journal of Gynecologic Oncology Vol.27 No.3

Objective: To explore the appropriate treatment of malignant germ cell tumor (MGCT) in thefemale genital system, and to analyze the factors influencing both therapeutic response andsurvival outcome. Methods: A cohort of 230-Chinese women diagnosed with MGCT of the genital systemwas retrospectively reviewed and prospectively followed. The demographic and pathologicalfeatures, extent of disease and surgery, treatment efficiency, recurrence and survival wereanalyzed. Results: MGCTs from different genital origins shared a similar therapeutic strategy andresponse, except that all eight vaginal cases were infantile yolk sac tumors. The patients’ curerate following the initial treatment, 5-year overall survival and disease-free survival (DFS)were 85.02%, 95.00%, and 86.00%, respectively. Although more extensive excision couldenhance the remission rate; it did not improve the patients’ survival. Instead, the level of themedical institution, extent of surgery and disease were independent prognostic factors forrelapse (p<0.05). Approximately 20% of patients had recurrent or refractory disease, morethan half of whom were in remission following secondary cytoreductive surgery with salvagechemotherapy. Conclusion: Fertility-sparing surgery with or without standardized PEB/PVB (cisplatin,etoposide/vincristine, and bleomycin) chemotherapy is applicable for female MGCTsof different origins. Comprehensive staging is not required; nor is excessive debulkingsuggested. Appropriate cytoreduction by surgery and antineoplastic medicine at anexperienced medical institution can bring about an excellent prognosis for these patients.

DIETARY TAURINE CAN IMPROVE THE HYPOXIA-TOLERANCE BUT NOT THE GROWTH PERFORMANCE IN JUVENILE GRASS CARP Ctenopharyngodon idellus

Huijun Yang,Lixia Tian,Junwa Huang,Guiying Liang,Yongjian Liu 한국수산과학회 양식분과 2015 한국수산과학회 양식분과 학술대회 Vol.2015 No.5