Rolling element-bearing feature extraction based on combined wavelets and quantum-behaved particle swarm optimization

Shuai Zhang,Yongxiang Zhang,Jieping Zhu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.2

A new approach is proposed to quickly determine the optimal band-pass filter for the resonant demodulation of rolling element bearings. The combined wavelet filter is joined with quantum-behaved particle swarm optimization for optimal filtering. The correlated kurtosisis used as an evaluation index to identify the optimal filtered signal. The proposed approach possesses good band-pass filteringproperties and improves optimal filtering speed and effect to converge rapidly to an optimal solution. Simulation and experiment resultsshow that this approach can generate fault features that are superior to those produced with the classic algorithm. It also shortens the timespent on the same filtering effect in comparison.

Synchronous Periodic Frequency Modulation Based on Interleaving Technique to Reduce PWM Vibration Noise

Zhang, Wentao,Xu, Yongxiang,Ren, Jingwei,Su, Jianyong,Zou, Jibin The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

Ear-piercing high-frequency noise from electromagnetic vibrations in motors has become unacceptable in sensitive environments, due to the application of pulse width modulation (PWM) and in consideration of switching losses. This paper proposed a synchronous periodic frequency modulation (SPFM) method based on the interleaving technique for paralleled three-phase voltage source inverters (VSIs) to eliminate PWM vibration noise. The proposed SPFM technique is able to effectively remove unpleasant high-frequency vibration noise as well as acoustic noise more effectively than the conventional periodic carrier frequency modulation (PCFM) and interleaving technique. It completely eliminates the vibration noise near odd-order carrier frequencies and reduces the PWM vibration noise near even-order carrier frequencies depending on the switching frequency variation range. Furthermore, the SPFM method is simple to implement and does not employ additional circuits in the drive system. Finally, the effectiveness of the proposed method has been confirmed by detailed experimental results.

RESEARCH ON 3D AERATION INFRASTRUCTURE SHAPE OF HIGH-HEAD, LARGE- DISCHARGE SPILLWAY TUNNEL

ZHANG DONG,LIU ZHIPING,GAO JIANBIAO,FENG YONGXIANG,CHEN WENXUE 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Mechanisms of dry flue-gas desulfurization using natural manganese oxide ores

Yongxiang Chen,Yunjiao LI,Xinlong Cao,Jianguo Li,Sanchuan Tang,Wanqi Ye,Xianzhen Zhang 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.7

The mechanisms of flue-gas desulfurization using high and low-grade natural manganese oxide ores were comparatively studied. Both manganese oxide ores exhibit good desulfurization capabilities with SO2 content in the effluents less than 30 ppm, but the low-grade ores show the much better desulfurization capability. XRD and SEM/EDS results reveal that the MnO2 absorbs the SO2 to convert to MnSO4. The SO2 give prior to react with the surface MnO2 and the produced MnSO2 enriched on the surface leads to the gradually decrease of the SO2 removal rate during desulfurization process. The better desulfurization capability of the low-grade ores is ascribed to the more dispersive MnO2 due to the poriferous/lax internal tunnel structure, and the embedded inert SiO2 shows better support effects to avoid pore structure blocking, which is favorable for enhancing the diffusion of the SO2 and desulfurization reaction process. This study is of significance in the comprehensive utilization of the low-grade natural manganese oxide ores, environmental protection and even the preparation of the desulfurization catalyst with MnO2.

Synchronous Periodic Frequency Modulation Based on Interleaving Technique to Reduce PWM Vibration Noise

Wentao Zhang,Yongxiang Xu,Jingwei Ren,Jianyong Su,Jibin Zou 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

Ear-piercing high-frequency noise from electromagnetic vibrations in motors has become unacceptable in sensitive environments, due to the application of pulse width modulation (PWM) and in consideration of switching losses. This paper proposed a synchronous periodic frequency modulation (SPFM) method based on the interleaving technique for paralleled three-phase voltage source inverters (VSIs) to eliminate PWM vibration noise. The proposed SPFM technique is able to effectively remove unpleasant high-frequency vibration noise as well as acoustic noise more effectively than the conventional periodic carrier frequency modulation (PCFM) and interleaving technique. It completely eliminates the vibration noise near odd-order carrier frequencies and reduces the PWM vibration noise near even-order carrier frequencies depending on the switching frequency variation range. Furthermore, the SPFM method is simple to implement and does not employ additional circuits in the drive system. Finally, the effectiveness of the proposed method has been confirmed by detailed experimental results.

Fault diagnosis of rolling bearings based on impulse feature enhancement and time-frequency joint noise reduction

Baoyu Huang,Yongxiang Zhang,Lei Zhao,Hao Chen 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.5

Aiming at the problem that the effectiveness of impulse feature enhancement (IFE) depends on the duration of high-level (or low-level) K and the number of high-level L, we regard a segmented impulse norm as the fitness function and combine it with the whale optimization algorithm to select the optimal parameters adaptively. Time-frequency joint noise reduction (TFJNR) is also proposed to suppress the noise components in the signal. Simulation and experimental results of rolling bearings indicate that the proposed algorithm can rapidly select the optimal parameters K and L to ensure the performance of IFE, while TFJNR has the ability to suppress the noise components in the signal. Fast kurtogram, empirical mode decomposition, and fast spectral correlation are also used for comparison. The results highlight the performance of the proposed algorithm.

Adaptive combined HOEO based fault feature extraction method for rolling element bearing under variable speed condition

Danchen Zhu,Yongxiang Zhang,Shuyong Liu,Qunwei Zhu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.10

It is still a challenge for condition monitoring and fault diagnosis for rolling element bearings working under variable speed, while some conventional diagnostic methods are useless. Order tracking is commonly used as an effective tool of the non-stationary vibration analysis for rotating machinery and tacho-less order tracking may be more applicable for practical situations, while the key point is to obtain more accurate instantaneous rotating speed. What’s more, the collected bearing fault vibration signals always contain strong background noise that greatly affects the result of fault feature extraction. To solve these problems, a fault feature extraction method is proposed in this study. The Chirplet-based approach was used to estimate some obvious harmonics of instantaneous rotating speed and the average value of these components was regarded as the final instantaneous rotating speed to reduce the estimation error. Since the higher order energy operator (HOEO) can not only improve the signal-to-noise ratio and signal-to-interference ratio, but is also easily applied, an adaptive combined HOEO method based on hybrid particle swarm optimizer with sine cosine acceleration coefficients (H-PSO-SCAC) was constructed to enhance the impulse components, and then, the fault features were extracted by the order spectrum analysis. Simulation and experimental results indicate that the proposed algorithm is effective for rolling element bearings’ fault diagnosis under variable speed condition.

Study on dynamic characteristics of the bladder fluid pulsation attenuator based on dynamic mesh technology

Qunwei Zhu,Yongxiang Zhang,Danchen Zhu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

Fluid-flow and pressure fluctuation are main causes of vibration and noise in liquid-conveying pipeline. As a crucial auxiliary component of liquid-conveying pipeline, the bladder pressure fluctuation attenuator plays an important role in absorbing fluctuations. According to the working condition, reasonable selection of attenuator parameters can give full play to the maximum efficiency of the attenuator so as to reduce pressure fluctuation of the pipeline. Based on the stress model of the attenuator, the mathematical and simulation models of the attenuation device are established by suitable hypothesis and simplification, and based on the calculation and physical models provided by FLUENT software, the movement of bladder was simulated by dynamic mesh and UDF (user-defined function). The absorption effect of attenuator on pipeline pressure fluctuation was investigated under different inflating pressures and frequencies. The results show that reasonable selection of initial pressure of the attenuator can effectively reduce the pressure fluctuation of pipeline fluid. Compared with the theoretical analysis results, the simulation results are more close to the experimental results, and the validity of the simulation model is verified, and a method and new idea are provided for the future study of the parameters of the bladder pressure fluctuation attenuator.

Research on constructing a degradation index and predicting the remaining useful life for rolling element bearings of complex equipment

Lei Zhao,Yongxiang Zhang,Jiawei Li 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10

Due to the interference of complex transmission path and noise, the weak characteristic signal of a fault in complex equipment is difficult to extract, and then it is hard to establish an index that can timely and effectively reflect the degradation state of the bearing fault. A bearing degradation state index was constructed by using moving average coarsegrained, fast iterative filtering decomposition, permutation entropy, Wasserstein distance and cumulative sum method, which realize the recognition and evaluation of bearing degradation state. On this basis, a hybrid model based on autoregressive integral moving average and nonlinear autoregressive neural network was constructed. Experimental study showed that the model could achieve accurately the residual life prediction of bearing for complex equipment.

Molecular dynamics study of H4TTP crystal morphology

Chen Jing,Li Jun,Li Yongxiang,Liu Qiao'e,Zhang Xuan,Ruan Jian,Wang Xiaojun,Liu Wendong,Kim Chan Kyung 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.7

To understand the role of dimethyl sulfoxide (DMSO) on the crystal growth morphology of 2,3,5,6-tetra(1H-tetrazol-5-yl)pyrazine (H4TTP), the vacuum morphology of H4TTP crystal was predicted by the Bravais–Friedel–Donnay–Harker (BFDH) and the attachment energy (AE) models. The growth morphology of H4TTP in DMSO solvent was predicted using a modified AE model. The results show that the main growth surfaces of H4TTP in vacuum are (1 0 0), (0 0 2), (0 1 1), and (1 1 0) surfaces. Among them, (1 0 0) surface is the most important growth surface. (0 0 2) surface is the roughest crystal surface, while (1 1 0) surface is the flattest. (1 1 0) surface grows rapidly, and (1 0 0) surface has the greatest morphological importance. The analysis of radial distribution function shows that (1 0 0) surface has the strongest hydrogen bonding interactions in the interface between H4TTP and DMSO solvent.