Aimed at the problem that Fourier decomposition method(FDM)is sensitive to noise and existing mode mixing cannot accurately extract gearbox fault features,a gear fault feature extraction method combining compound dict...Aimed at the problem that Fourier decomposition method(FDM)is sensitive to noise and existing mode mixing cannot accurately extract gearbox fault features,a gear fault feature extraction method combining compound dictionary noise reduction and optimized FDM(OFDM)is proposed.Firstly,the characteristics of the gear signals are used to construct a compound dictionary,and the orthogonal matching pursuit algorithm(OMP)is combined to reduce the noise of the vibration signal.Secondly,in order to overcome the mode mixing phenomenon occuring during the decomposition of FDM,a method of frequency band division based on the extremum of the spectrum is proposed to optimize the decomposition quality.Then,the OFDM is used to decompose the signal into several analytic Fourier intrinsic band functions(AFIBFs).Finally,the AFIBF with the largest correlation coefficient is selected for Hilbert envelope spectrum analysis.The fault feature frequencies of the vibration signal can be accurately extracted.The proposed method is validated through analyzing the gearbox fault simulation signal and the real vibration signals collected from an experimental gearbox.展开更多
In the first part of this paper, different perspectives of time proposed in Aristotle's philosophy of nature, classic mechanics, thermodynamics, and the theory of relativity, will be presented. Later on, we explore t...In the first part of this paper, different perspectives of time proposed in Aristotle's philosophy of nature, classic mechanics, thermodynamics, and the theory of relativity, will be presented. Later on, we explore the phenomenological approach of duration by Henri Bergson and Mauro Dorato's naturalistic proposal, which defines the "present" moment based on neuroscientific experiments. In the second part of the paper, the topic of scientific creativity is introduced, paying particular attention to David Bohm's ideas. Finally, the previously analysed perspectives are used to answer the following question: How do physicists create time?展开更多
基金The National Natural Science Foundation of China(No.51975117)the Key Research&Development Program of Jiangsu Province(No.BE2019086).
文摘Aimed at the problem that Fourier decomposition method(FDM)is sensitive to noise and existing mode mixing cannot accurately extract gearbox fault features,a gear fault feature extraction method combining compound dictionary noise reduction and optimized FDM(OFDM)is proposed.Firstly,the characteristics of the gear signals are used to construct a compound dictionary,and the orthogonal matching pursuit algorithm(OMP)is combined to reduce the noise of the vibration signal.Secondly,in order to overcome the mode mixing phenomenon occuring during the decomposition of FDM,a method of frequency band division based on the extremum of the spectrum is proposed to optimize the decomposition quality.Then,the OFDM is used to decompose the signal into several analytic Fourier intrinsic band functions(AFIBFs).Finally,the AFIBF with the largest correlation coefficient is selected for Hilbert envelope spectrum analysis.The fault feature frequencies of the vibration signal can be accurately extracted.The proposed method is validated through analyzing the gearbox fault simulation signal and the real vibration signals collected from an experimental gearbox.
文摘In the first part of this paper, different perspectives of time proposed in Aristotle's philosophy of nature, classic mechanics, thermodynamics, and the theory of relativity, will be presented. Later on, we explore the phenomenological approach of duration by Henri Bergson and Mauro Dorato's naturalistic proposal, which defines the "present" moment based on neuroscientific experiments. In the second part of the paper, the topic of scientific creativity is introduced, paying particular attention to David Bohm's ideas. Finally, the previously analysed perspectives are used to answer the following question: How do physicists create time?