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RISS 인기검색어
- 검색키워드
- 저자 : Fanming Meng (검색결과 4 건)
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Effect of the cut-off frequency on rough-point and flat-surface contacts
Fanming Meng 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.9
In the past years, contact between two bodies has been studied from various ways that do not consider the cut-off frequency effect on the contact mechanism. This paper reports the correlation between rough point contact and flat surface contact at different cut-off frequencies of filter. The similarity and difference between the two types of contact mechanisms are presented for materials with linear or elasticperfectly plastic deformation. The conjugate gradient method (CGM) is used for analysing the rough point contact, while the rough flat surface contact is studied with an improved CGM in which the influence coefficient for the elastic deformation of the rough flat surface is obtained with finite element method. Numerical results show that for the above two types of contacts, their von Mises stress and maximum shear stress are greatly affected by the cut-off frequency of a high-pass filter. Moreover, a decrease in the cut-off frequency leads to an increase in the contact area and a decrease in the approach for the rough flat surface contact, while the opposite variations is for the point contact between rough bodies with the small radii.
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Jinfeng Gong,Fanming Meng,Zhenghua Fan,Huijie Li 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.6
Monodisperse 3D lotus-like CeO2 microstructures have beensuccessfully synthesized via controlling the morphology ofCeCO3OH precursors under hydrothermal condition as wellas subsequent calcination. The reaction time wassystematically investigated. XRD, FT-IR, SEM, TEM, XPS,Raman scattering and Photoluminescence (PL) spectra wereemployed to characterize the samples. The lotus-like CeO2hierarchical structures with an average of 4-6 μm arecomposed of many nanoplates of 100-200 nm in thickness asthe petals stacking together to form open flowers and have a fluorite cubic structure. Based on the time-dependent morphologyevolution evidences, a nucleation-dissolution-recrystallization mechanism has been proposed to explain the transformation fromrod-like structures to lotus-like CeO2 hierarchical structures with the increase of reaction time. It is found that there are Ce3+ ionsand oxygen vacancies in surface of samples. The magnetic and photoluminescence measurements indicated that all CeO2samples exhibit excellent ferromagnetism and optical properties at room temperature, and while increasing the reaction time, theferromagnetism and optical properties increase more, which can be reasonably explained for the influences of the differentmorphology of the particles and the concentration of oxygen vacancies and Ce3+ ions.
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Huijie Li,Fanming Meng,Jinfeng Gong,Zhenghua Fan,Rui Qin 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.4
CeO2 nanospheres with the core–shell nanostructure have been successfully synthesized by a template-free hydrothermalmethod. The structures, morphologies and optical properties of core–shell CeO2nanospheres were analyzed by X-ray diffraction(XRD), TG, Fourier transform infrared spectroscopy, XRD, EDS, SAED, scanning electron microscopy and transmissionelectron microscopy, UV–Vis diffuse reflectance spectra, Raman analyses. The degradation efficiencies of core–shell CeO2nanospheres for methyl orange were as high as 93.49, 95.67 and 98.28% within 160 min, and the rates of photo degradationof methyl orange by core–shell CeO2nanospheres under UV-light were 0.01693, 0.01782 and 0.02375 min−1. Methyl orangewas degraded in photocatalytic oxidation processes, which mainly gave the credit to a large number of reactive species includingh+,surface superoxide species ·O2−, and ·OH radicals. The core–shell structure, small crystallite size and the conversionbetween Ce3+and Ce4+of CeO2nanospheres were of importance for its catalytic activity. These results demonstrated thepossibility of improving the efficient catalysts of the earth abundant CeO2catalysts.
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Jing Wei,Ruizhi Shu,Datong Qin,Teik C. Lim,Aiqiang Zhang,Fanming Meng 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.9
Multi-source driving transmission systems, in which the gear assembly is driven by multiple induction motors, are extensively used in new energy, aerospace, marine engineering, and in other fields. The multi-source driving system faces an even-load distribution problem, i.e., torque or speed synchronization issues. In this study, the synchronization characteristics of a multi-source driving transmission system under an impact load at different load change rates are studied. An accurate electromechanical coupling dynamic model of the system considering the flexible shafts, support bearing and meshing gear pair is established by applying virtual equivalent shaft elements. By considering the time-varying meshing and the coupling effects of the dynamic electric motor and the speed, torque and stator current synchronization characteristics are investigated using this model. Computational results show that the influence of the load change rate on the speed synchronization characteristics of the system is minor, but has a significant influence on the torque and stator current synchronization characteristics. The stator current root mean square value (RMS) can be chosen as a feedback signal to monitor the synchronization characteristics of the system. The proposed research provides the theoretical basis for the formulation of the synchronization control strategy for multi-source driving transmission systems.
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