Refined time-shift multiscale dispersion Lempel-Ziv complexity to diagnose rolling bearing faults

Yongjian Li,Li Tan,Peng Li,Qing Xiong 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

The key to damage detection is whether fault features can be extracted effectively from raw signals. Hence, we propose an approach based on the refined time-shift multiscale dispersion Lempel-Ziv complexity (RTSMDLZC) to effectively extract fault features. First, the time-shift multiscale sequence constructed from the raw time series can obtain more fault information more effectively. Then, the refined method addresses the lacking of sizeable numerical fluctuation on a large scale and enhances the algorithm's stability. Simulation signals and two experimental cases verify the effectiveness and applicability of the RTSMDLZC. The results indicate that compared with other classic methods, the RTSMDLZC can extract bearing fault features more accurately and has better identification accuracy.

A rolling bearing fault diagnosis strategy based on improved multiscale permutation entropy and least squares SVM

Yongjian Li,Weihua Zhang,Qing Xiong,Dabing Luo,Guiming Mei,Tao Zhang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6

A novel rolling bearing fault diagnosis strategy is proposed based on Improved multiscale permutation entropy (IMPE), Laplacianscore (LS) and Least squares support vector machine-Quantum behaved particle swarm optimization (QPSO-LSSVM). Entropy-basedconcepts have attracted attention recently within the domain of physiological signals and vibration data collected from human body orrotating machines. IMPE, which was developed to reduce the variability of entropy estimation in time series, was used to obtain moreprecise and reliable values in rolling element bearing vibration signals. The extracted features were then refined by LS approach to form anew feature vector containing main unique information. By constructing the fault feature, the effective characteristic vector was input toQPSO-LSSVM classifier to distinguish the health status of rolling bearings. The comparative test results indicate that the proposed methodologyled to significant improvements in bearing defect identification.

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.

DE-Based Reversible Data Hiding With Improved Overflow Location Map

Yongjian Hu,Heung-Kyu Lee,Jianwei Li IEEE 2009 IEEE transactions on circuits and systems for vide Vol.19 No.2

<P>For difference-expansion (DE)-based reversible data hiding, the embedded bit-stream mainly consists of two parts: one part that conveys the secret message and the other part that contains embedding information, including the 2-D binary (overflow) location map and the header file. The first part is the payload while the second part is the auxiliary information package for blind detection. To increase embedding capacity, we have to make the size of the second part as small as possible. Tian's classical DE method has a large auxiliary information package. Thodi mitigated the problem by using a payload-independent overflow location map. However, the compressibility of the overflow location map is still undesirable in some image types. In this paper, we focus on improving the overflow location map. We design a new embedding scheme that helps us construct an efficient payload-dependent overflow location map. Such an overflow location map has good compressibility. Our accurate capacity control capability also reduces unnecessary alteration to the image. Under the same image quality, the proposed algorithm often has larger embedding capacity. It performs well in different types of images, including those where other algorithms often have difficulty in acquiring good embedding capacity and high image quality.</P>

Radial Depth Damage Properties of Coal Tunnels Surrounded by Rock under Excavation and Unloading

Peng Li,Yongjian Zhu,Ping Wang,Chengcheng Mei 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

In order to study the mechanism of radial gradient damage of surrounding rock caused by deep elevated stress coal roadway excavation, a triaxial loading unloading uniaxial reloading coal sample damage test was carried out. Based on the defined damage factor and fractal theory, the wave velocity damage characteristics, fracture characteristics, three-dimensional fractal characteristics and uniaxial reloading strength characteristics of coal samples under different loading unloading paths were studied. The results show that the shift of wave velocity can better reflect the damage of coal samples. Under the same confining pressure, the damage amount of coal samples increases with the axial compression ratio index, and the confining pressure can inhibit the damage of coal samples to a certain extent; the fracture characteristics of coal samples are closely related to the loading history. The surface cracks of coal samples tend to become complex with the increase of axial compression ratio, but eventually develop to the shear plane fracture surface; the surface cracks of damaged coal samples under the radial stress gradient of surrounding rock have excellent fractal characteristics. The fractal dimension has a linear function relationship with axial compression loading ratio and wave velocity damage; from the angle of wave velocity damage and strength loss, it is expounded that the increase of confining pressure can inhibit low damage to a certain extent, but can promote the occurrence of extreme damage.

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.

Value of Information Sharing in Inventory Management of Maintenance Spare Parts

Haiju Hu,Yongjian Li,Xinjiang Cai 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.7

This study uses the system dynamics tool Vensim to conduct simulation on two different types of maintenance spare parts information sharing models (i.e. the inter-user joint maintenance spare parts management model and the supplier-involved joint maintenance spare parts management model) as well as the spare parts management model without the implementation of information sharing. By comparing the change of revenues of both the supply and the demand sides before and after the implementation of information sharing, as well as under different information sharing models, we propose the optimal way of information sharing, and also contribute managerial implications for the implementation of information sharing in maintenance spare parts inventory management.

Polyaniline/Cerium Oxide Hybrid Modified Carbon Paste Electrode for Non-Enzymatic Glucose Detection

Jie Zhang,Panpan Guan,Yongjian Li,Wei Li,Qingping Guo 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.7

Ameliorative effects of atractylodin on intestinal inflammation and co-occurring dysmotility in both constipation and diarrhea prominent rats

Yu, Changchun,Xiong, Yongjian,Chen, Dapeng,Li, Yanli,Xu, Bin,Lin, Yuan,Tang, Zeyao,Jiang, Chunling,Wang, Li The Korean Society of Pharmacology 2017 The Korean Journal of Physiology & Pharmacology Vol.21 No.1

Intestinal disorders often co-occur with inflammation and dysmotility. However, drugs which simultaneously improve intestinal inflammation and co-occurring dysmotility are rarely reported. Atractylodin, a widely used herbal medicine, is used to treat digestive disorders. The present study was designed to characterize the effects of atractylodin on amelioration of both jejunal inflammation and the co-occurring dysmotility in both constipation-prominent (CP) and diarrhea-prominent (DP) rats. The results indicated that atractylodin reduced proinflammatory cytokines TNF-${\alpha}$, IL-$1{\beta}$, and IL-6 in the plasma and inhibited the expression of inflammatory mediators iNOS and NF-kappa B in jejunal segments in both CP and DP rats. The results indicated that atractylodin exerted stimulatory effects and inhibitory effects on the contractility of jejunal segments isolated from CP and DP rats respectively, showing a contractile-state-dependent regulation. Atractylodin-induced contractile-state-dependent regulation was also observed by using rat jejunal segments in low and high contractile states respectively (5 pairs of low/high contractile states). Atractylodin up-regulated the decreased phosphorylation of 20 kDa myosin light chain, protein contents of myosin light chain kinase (MLCK), and MLCK mRNA expression in jejunal segments of CP rats and down-regulated those increased parameters in DP rats. Taken together, atractylodin alleviated rat jejunal inflammation and exerted contractile-state-dependent regulation on the contractility of jejunal segments isolated from CP and DP rats respectively, suggesting the potential clinical implication for ameliorating intestinal inflammation and co-occurring dysmotility.