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Mengchen Zhang,Xu Cui,Qinglei Xiu,Jian Zhuang,Xuefeng Yang 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.4
For the 4th generation synchrotron radiation source, the piezoelectric actuator (PEA) becomes the crucial component of the beam-line to guarantee the beam stability during the high accuracy experiments. However, the rate-dependent hysteresis seriously affects the accuracy of PEA. To eliminate this nonlinear error, we present a feedforward controller and an integrated controller. A novel Hammerstein model is proposed to describe the rate-dependent hysteresis of the PEA, which is composed of a static Preisach model and a dynamic transfer function. The insufficiency of the classic Preisach model in describing the nature of the zero drift of hysteresis loops is improved by inducing a correction item. Moreover, the identification and the inversion method of the dynamic model are proposed as well. Experiments on the commercial PEA demonstrate that the hysteresis with the frequency in range of 0–80 Hz is compensated more than 80% under the proposed control scheme.
Fundamental Frequency Tracking of Distorted Power Signal Based on the Improved EKF Algorithm
Zhang Xiaobing,Yang Mengchen,Yan Yixin,Fang Guozhi 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.10
To reduce the impacts of harmonics and noises on frequency measurements, a novel method of frequency tracking is presented based on improved EKF algorithm and wavelet transform. Firstly, the power signal was preprocessed to extract the fundamental wave by wavelet filtering. Then, an improved Extended Kalman Filter was introduced to achieve fast and accurate frequency tracking. By adding a robust factor and modifying the covariance matrix in real time, it enhanced the stability for detecting distorted signals. The proposed tracking algorithm can effectively solve the problems of traditional Extended Kalman Filter such as lack of adaptability, instability and divergence. And it improved the tracking speed and accuracy. Finally, Detailed simulations on several typical models of power signals have been carried out and the Simulation results shown that the new algorithm increases the speed, convergence and accuracy. It effectively suppresses the impacts of harmonics and noises on the frequency tracking results.
Lu Ming,Li Min,Luo Tao,Li Yongsui,Wang Mingxin,Xue Huashi,Zhang Mengchen,Chen Qiu 대한독성 유전단백체 학회 2023 Molecular & cellular toxicology Vol.19 No.3
Background Treating large-volume bone defects (LVBD) remains a challenge for orthopedics and maxillofacial surgeons globally. Objective The present study was to aimed investigate the role of Beta-naphthofl avone (BNF) a synthetic fl avonoid on differentiation of osteoblast of human adipose derived stem cells. Results BNF at 1 μM showed a signifi cantly increased ALP activity and rate of cell proliferation compared to control on the 3rd, 7th and 14th day. Also, it was observed that, BNF at 1 μM resulted in signifi cantly increased expression of BSP. On the 14th day of treatment, BNF at all the three treatments resulted in increased levels of OCN. Also, extracellular matrix mineralization levels were recorded to be highest for BNF 1 μM. The levels of Runx2 were higher in 1 μM treated group on the 3rd day compared to other, whereas in contrast the levels were lower on the 7th and 14th day compared to control. BNF at all the three treatments caused a signifi cant decrease in levels of pSTAT3, C/EBP-α and PPAR-γ levels. Conclusion BNF treatment resulted in increased diff erentiation of osteoblast of hASCs by targeting STAT3 pathway.