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- 저자 : XUEZHONG WU (검색결과 5 건)
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Yongmeng Zhang,Xuezhong Wu,Yulie Wu,Xiang Xi,Yi Tao 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.4
In this paper, vibration of imperfect resonators for vibratory cylinder gyroscopes is investigated. A model of the vibration based on the wave superposition is established. For an imperfect resonator, the principal stiffness axis does not coincide with the driving electrodes, so the primary mode and the secondary mode of the resonator are both excited. Superposition of these two pattern components produces the resultant pattern, which leads to a complicated vibration near the nodes and the pattern angle error. The influence of the frequency split and the driving vector orientation on the nodal vibration and the pattern angle error is particularly analyzed. Theoretical results show that the amplitude and phase of the nodal vibration are affected by the frequency split and the driving vector orientation. The pattern angle error has a positive correlation with the frequency split, and this angle also has a positive proportion with sin(8α), where α is the angle between the drive electrodes and the principal stiffness axis of the primary mode. Experiments are also included in this work to validate these influence factors. The theoretical and measured results are in close agreement. These results are useful for the mechanical balance, the electrodes assembly and the control circuit design of the cylindrical gyroscopes.
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DI DI,PEITAO DONG,XUEZHONG WU,CHAOGUANG WANG,JIAN CHEN,HAOXU WANG,SHENGYI LI,JUNFENG WANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.4
High-ordered particle-in-bowl (PIB) arrays are developed in this paper for surface enhancedRaman spectroscopy (SERS). A heterogeneous shadow mask, composing of the chrome (Cr) layerand colloid residues, is used to fabricate the silicon (Si) template from where the PIB arrays¯nally lift-o®. The ¯nite di®erence time domain (FDTD) method is employed to investigate theRaman enhancement mechanism of this PIB architecture. The electromagnetic (EM) ¯eld tendsto concentrate in the gap between the bowl and the particle forming the \hot spots". Theenhancement factor (EF) of the EM ¯eld is about 70 with an excitation wavelength of 785 nm. The Raman measurements validate the EM calculation of the PIB arrays. The EF is about1 : 12 ? 10 7 using Rodamine 6G (R6G) as probe molecule. The proposed PIB array is high-orderedin morphology and ultra-sensitive in Raman measurement, providing an ideal substrate forSERS-based bio-chemical sensing, disease diagnosis and analytical chemistry.
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Yongmeng Zhang,Yulie Wu,Xinxin Xu,Xiang Xi,XUEZHONG WU 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.12
Due to the material defects, manufacture errors and internal stress, the vibration axis stability of the vibratory cylinder gyroscope is highly influenced by environment temperature. According to the influencing rule of the internal stress on the vibrating axis, a special resonator structure is proposed which can generate oriented thermal stress to reduce the temperature drift of vibrating axis of the resonator. Firstly, the drift trend of the vibrating axis under varying temperature is analyzed. Secondly, thermal stress structures with holes and grooves are fabricated in special direction at the bottom of the resonator. Those thermal stress structures can generate thermal stress to make the vibrating axis rotate in the opposite direction, which can reduces the gyroscope’s temperature drift. Finally, simulations and experiments are conducted and results show that the proposed method can give good compensation effect for temperature drift of the vibratory cylinder gyroscope.
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Jian Chen,Peitao Dong,Chaoguang Wang,Chenyu Zhang,Junfeng Wang,Xuezhong Wu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.11
A simple method for improving surface-enhanced Raman scattering (SERS) performance of aligned silver nanorod (Ag NR) array was investigated. This method was to construct a kind of hybrid substrate by grafting Au@Ag core–shell nanoparticles (NPs) into Ag NR array using poly(2-vinylphridine) (P2VPy) as a bridging agent. The hybrid substrate yielded excellent SERS performance as its detection limit improved from 10 -6 M to 10 -8 M using trans-1,2-bis(4-pyridyl)ethylene (BPE) as probe molecule, which was increased by two orders of magnitude compared with Ag NR array substrate. The significant improvement of SERS performance of Ag NR arrays was attributed to the addition of Au@Ag core–shell NPs. As a result of surface plasmon resonance generated by the interaction of electromagnetic (EM) (IAEM) filed between NP and NR structures, increasing hotspots were found at the connections of NPs and NRs, the gaps of adjacent rods, and the gaps of two particles consequently. These results were validated by the finite difference time domain (FDTD) calculation. Besides, hybrid substrate shows good performance in stability and reproducibility. The proposed method was simple and robust, which promoted SERS performance of Ag NR array effectively, showing great potential in the application of SERS substrate fabrication and SERS-based bio-chemical sensing.
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Quantifying carotid stiffness in a pre-hypertensive population with ultrafast ultrasound imaging
Xuehui Ma,Zhengqiu Zhu,Yinping Wang,Bixiao Shen,Xuezhong Jiang,Wenjun Liu,Yiyun Wu,Chong Zou,Yun Luan,Hui Gao,Hui Huang 대한초음파의학회 2023 ULTRASONOGRAPHY Vol.42 No.1
Purpose: The aim of this study was to assess carotid stiffening in a pre-hypertensive (PHT) population using ultrafast pulse wave velocity (ufPWV). Methods: This study retrospectively enrolled 626 individuals who underwent clinical interviews, serum tests, and assessments of the systolic blood pressure (SBP), diastolic blood pressure (DBP), carotid intima-media thickness (cIMT), pulse wave velocity-beginning of systole (PWV-BS), and pulse wave velocity-end of systole (PWV-ES) between January 2017 and December 2021. The patients were divided into three groups according to their blood pressure (BP)—normal BP (NBP): SBP <130 mmHg and DBP <80 mmHg (n=215); PHT: 130 mmHg≤SBP<140 mmHg and/or 80 mmHg≤DBP<90 mmHg (n=119); hypertensive (HT): SBP ≥140 mmHg and/or DBP ≥90 mmHg (n=292). Correlation analyses and comparisons were performed among the groups and in the cIMT subgroups (cIMT ≥0.050 cm and <0.050 cm). Results: cIMT and PWV-ES significantly differed among the BP groups (P<0.05). The BP groups had similar PWV-BS when cIMT <0.050 cm or cIMT ≥0.050 cm (all P>0.05). However, the NBP group had a notably lower PWV-ES than the PHT (P<0.001 and P=0.024) and HT (all P<0.001) groups in both cIMT categories, while the PWV-ES in the PHT group were not significantly lower than in the HT group (all P>0.05). Conclusion: Carotid morphological and biomechanical properties in the PHT group differed from those in the NBP group. ufPWV could be used for an early evaluation of carotid stiffening linked to pre-hypertension.
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