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Thrust Ripples Suppression of Permanent Magnet Linear Synchronous Motor
Yu-wu Zhu,Yun-Hyun Cho IEEE 2007 IEEE transactions on magnetics Vol.43 No.6
<P>The thrust ripples in permanent magnet linear synchronous motor (PMLSM) are mainly generated by the distortion of the stator flux linkage distribution, reluctance force due to the relative position between the mover and stator, cogging force caused by the interaction between the permanent magnet (PM) and the iron core, and the end effects. This is the significant drawback which will deteriorate the performance of the drive system in high-precision applications. Comparing the complexity of the motor structure design to eliminate the thrust ripples, an optimal control method is more desirable. This paper focuses on thrust ripples reduction based on the predictive control algorithm. To minimize the thrust ripples and realize the high-precision control, the components of thrust ripples are extracted by finite element method (FEM) first and then compensated by injecting the instantaneous current to counteract the thrust ripples using the field-oriented control (FOC) method. The effectiveness of this proposed method is verified by the simulation using Simulink/Matlab according to the comparison between the compensation and noncompensation cases</P>
Control Based Reduction of Detent Force for Permanent Magnet Linear Synchronous Motor
Yu-wu Zhu(주옥오),Yun-hyun Cho(조윤현) 전력전자학회 2008 전력전자학술대회 논문집 Vol.- No.-
The detent force of the permanent magnet linear synchronous motor (PMLSM) is caused by the interaction between the permanent magnet and the iron core of the mover without input current. It is a function of the mover position relative to the stator. This paper proposes a control based method to reduce the detent force for the PMLSM. This detent force that can be predicted by finite element method (FEM) is compensated by injecting the instantaneous current using the field oriented control (FOC) method. Both the simulated and experimental results are reported to validate the effectiveness of this proposed method.
Ding, Xiao-Yu,Xu, Qiu,Zhu, Xiao-yong,Luo, Lai-Ma,Huang, Jian-Jun,Yu, Bin,Gao, Xiang,Li, Jian-Gang,Wu, Yu-Cheng Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.12
Oxide dispersion-strengthened materials W-1wt%Pr<sub>2</sub>O<sub>3</sub> and W-1wt%La<sub>2</sub>O<sub>3</sub> were synthesized by wet chemical method and spark plasma sintering. The field emission scanning electron microscopy (FE-SEM) analysis, XRD and Vickers microhardness measurements were conducted to characterize the samples. The irradiations were carried out with a 5 keV helium ion beam to fluences up to 5.0 × 10<sup>21</sup> ions/m<sup>2</sup> under 600 ℃ using the low-energy ion irradiation system. Transmission electron microscopy (TEM) study was performed to investigate the microstructural evolution in W-1wt%Pr<sub>2</sub>O<sub>3</sub> and W-1wt%La<sub>2</sub>O<sub>3</sub>. At 1.0 × 10<sup>20</sup> He<sup>+</sup>/m<sup>2</sup>, the average loops size of the W-1wt%Pr<sub>2</sub>O<sub>3</sub> was 4.3 nm, much lower than W-1wt% La<sub>2</sub>O<sub>3</sub> of 8.5 nm. However, helium bubbles were not observed throughout in both doped W materials. The effects of pre-irradiation with 1.0 × 10<sup>21</sup> He<sup>+</sup>/m<sup>2</sup> on trapping of injected deuterium in doped W was studied by thermal desorption spectrometry (TDS) technique using quadrupole mass spectrometer. Compared with the samples without He<sup>+</sup> pre-irradiation, deuterium (D) retention of doped W materials increased after He<sup>+</sup> irradiation, whose retention was unsaturated at the damage level of 1.0 × 10<sup>22</sup>D<sub>2</sub><sup>+</sup>/m<sup>2</sup>. The present results implied that irradiation effect of He<sup>+</sup> ions must be taken into account to evaluate the deuterium retention in fusion material applications.
Structural transformation, spectroscopic characterization and magnetic properties of La1xGdxCoO3
Yu Gao,Hong Chang,Qiang Wu,P. Suresh Kumar,Meiling Li,Fang Liu,Hongjing Zhu,Yanbo Pang,Yuehou Yun 한국물리학회 2016 Current Applied Physics Vol.16 No.8
La1xGdxCoO3 for x < 0.2 crystallize in the rhombohedral structure, and it is orthorhombic for x 0:2. The lattice volume systematically decreases as x increases. The analysis of the Co 2p3/2 xps spectra indicates that the Co ions are at both þ3 and þ8/3 valence states, and the calculated oxygen content is about 2.93 per formula unit. The bending vibration of the CoeO bond linearly shifts from 429 cm1 to 482 cm1 with the increasing x, and it is coincident with the increasing CoeOeCo angle. The shoulder peak at approximately 575 cm1 becomes obviously wide with the increasing doping Gd3þ content owing to the magnetic interactions of the Gd3þ ions with the surrounding CoO6 octahedra. The energy band gap slightly increases from about 2.40 eV to about 2.75 eV as the structure transforms from the rhombohedral to the orthorhombic structure. The magnetic properties are ferrimagnetic with x ¼ 0.05, 0.3 and 0.7. However, the calculated Curie-Weiss temperature and constant of La0.3Gd0.7CoO3 are not reasonable, it is probably due to a nonlocalized electronic state.
Novel method for equivalent stiffness and Coulomb’s damping ratio analyses of leaf spring
Wu Wen-jun,Zhu Le-mei,Xiang Yu,He Li-jun 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.11
The leaf spring is a representative type of laminated structure. Based on the linear theories of curve beams, the first derivatives of the leave’s status-vector of the leaf spring are provided. The first derivatives of the combination status-vector are obtained by properly dealing with the nonlinear interacted forces between adjacent leaves. Moreover, the precise integration technology and the transform matrix method are introduced to solve the equations. The force-displacement curve of a leaf spring is then calculated separately by using the present method and the finite element software ANSYS. From the results, the precision and advantages of the present methods for analyzing the leaf spring are revealed. The Coulomb’s damping ratio of the leaf spring is studied by using the present method.
Zhu, Hongmei,Wu, Enqi,Chen, Jianbo,Men, Chuvan,Jang, Yu-Seon,Kang, Won-Ku,Choi, Jung-Kap,Lee, Won-Jae,Kang, Jong-Seong Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.6
Sibutramine enantiomers were separated successfully by capillary zone electrophoresis using substituted cyclodextrins as chiral selectors. The effects of cyclodextrin concentration, pH, voltage, buffer type, and electrolyte concentration on the migration time and resolution of enantiomers were examined. Separation of sibutramine enantiomers on an unmodified fused silica capillary (total length, 54 cm; effective length, 45 cm) was achieved using a mixed buffer of 20 mM phosphate/10 mM citrate containing either 5 mM methyl-${\beta}$-cyclodextrin (pH 4.3) or 5 mM carboxymethyl-${\beta}$-cyclodextrin (pH 6.5). Samples were injected with a pressure of 50 mbar for 5 s and were detected at a wavelength of 223 nm. The established method showed good precision and accuracy, with intra- and inter-day variations of less than 2.9 and 4.7%, respectively, and recoveries of 95.7 - 103.8%. The stability constants of (R)- and (S)-sibutramine demonstrated that the resolution of sibutramine enantiomers was attributable primarily to the difference in stability constants. When this optimized method was applied to the determination of sibutramine enantiomers in commercial drug formulations, it proved to be economical and convenient, affording sufficient accuracy, precision, and reproducibility as well as sensitivity and selectivity.
Wu, Kai,Yang, Liu,Li, Cong,Zhu, Chao-Hui,Wang, Xin,Yao, Yi,Jia, Yu-Jie Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.14
Helicobacter pylori (H. pylori) infection induces apoptosis in gastric epithelial cells, and this occurrence may link to gastric carcinogenesis. However, the regulatory mechanism of H. pylori-induced apoptosis is not clear. MicroRNA-146a has been implicated as a key regulator of the immune system. This report describes our discovery of molecular mechanisms of microRNA-146a regulation of apoptosis in human gastric cancer cells. We found that overexpression of microRNA-146a by transfecting microRNA-146a mimics could significantly enhance apoptosis, and this upregulation was triggered by COX-2 inhibition. Furthermore, we found that microRNA-146a density was positively correlated with apoptosis rates in H. pylori-positive gastric cancer tissues and intratumoral microRNA-146a density was negatively correlated with lymph node metastasis among H. pylori-positive gastric cancer patients. Understanding the important roles of microRNA-146a in regulating cell apoptosis in H. pylori infected human gastric cancer cells will contribute to the development of microRNA targeted therapy in the future.