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RISS 인기검색어
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- 저자 : Qiuze Li (검색결과 2 건)
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The Application of Hilbert-Huang Transform in the Abnormal Vibration Analysis for Metro Vehicle
Qiuze Li,Huailong Shi,Jianbin Wang,Pingbo Wu 한국도시철도학회 2014 IJAR Vol.2 No.1
The time-frequency analysis method Hilbert-Huang Transform (HHT) is applied in the signal processing for metro vehicle, in order to analyze and research the reason of abnormal vibration of carbody floor. The linear superposition property and the actual physical meaning of marginal spectrum are demonstrated to assess the vibration characteristic of structure. The rail vehicle is a nonlinear system and unsteady process. All kinds of frequency domain analysis method based on Fourier Transform is short to study on the un-linear and unsteady system, cannot use it to search the abnormal vibration reason. HHT is an effective tool to research the nonlinear and unsteady process, describing the vibration amplitude changing process with time and frequency. Compared to the test results and considered that the abnormal vibration frequency come from the two times frequency components about the traction motor rotating speed which is transferred to the floor through the vehicle suspension system. The frequency is close to the natural frequency of local floor and stimulates local elastic vibration of the floor significantly. At last, the paper pointed that the frequency component maybe caused by the misalignment of flexible-coupling.
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Spectral Diagnostic for the Soft X-ray Fe XVII Spectral Line in the Solar Corona
Jian He,Qingguo Zhang,Qiuze Li 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.8
In this paper, taking the soft X-ray Fe XVII 1.501-nm spectral line in the solar corona as an example, we analyze the effect of opacity on the 1.501-nm spectral line, and we discuss the diagnostic principle for the plasma temperature and the electron density. Results show that the plasma temperature in the solar coronal has an order of magnitude of 106 K and that the electron density has an order of magnitude of 1010 cm−3, which are in good agreement with the reported values. Through analysis, we show that the opacity has a great effect on the 1.501-nm spectral line and that the electron density is connected with the temperature. The results of this study are significant and valuable in solar coronal plasma diagnostics.
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