Results 211 to 220 of about 781,573 (274)

Study of Time-Frequency Order Tracking of Vibration Signals of Rotating Machinery in Changing State

2008 International Symposiums on Information Processing, 2008
Order tracking is an important method for condition monitoring and fault diagnosis, dynamic analysis and design in rotating machinery. Especially, the hidden fault is usually easier to discover at engine run up/down. Order tracking is implemented by band pass filter in time-frequency domain and time signal of desired order is reconstructed. Compared to
Xiaoping Zhao, Qingpeng Kong, Qingtao Guo   +2 more
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Hydration-Induced Changes of Structure and Vibrational Frequencies of Methylphosphocholine Studied as a Model of Biomembrane Lipids

The Journal of Physical Chemistry B, 2005
The chemical characteristics of the polar parts of phospholipids as the main components of biological membranes were investigated by using infrared (IR) spectroscopy and theoretical calculations with water as a probe molecule. The logical key molecule used in this study is methylphosphocholine (MePC) as it is not only a representative model for a polar
E, Mrázková, P, Hobza, M, Bohl, D R, Gauger, W, Pohle   +4 more
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Resonant phenomena and mechanism in vibrated granular systems.

Physical Review E, 2020
We were motivated to perform this research by the investigation of Brownian motors in excited granular materials converting the chaotic motion of granules into the oriented motion of motors.
H. Cai, G. Miao
semanticscholar   +1 more source

Sensibility to Changes of Vibrational Modes of Excited Electron: Sum Frequency Signals Versus Difference Frequency Signals

Communications in Theoretical Physics, 2011
In this paper, we investigate a two electronic level system with vibrational modes coupled to a Brownian oscillator bath. The difference frequency generation (DFG) signals and sum frequency generation (SFG) signals are calculated. It is shown that, for the same model, the SFG signals are more sensitive than the DFG signals to the changes of the ...
An-Na Gu, Xian-Ting Liang
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Aspects of change detection in vibrational processes based on time-frequency transforms

2017 5th International Symposium on Electrical and Electronics Engineering (ISEEE), 2017
The main goal of the work is to present some aspects in using time-frequency transforms, applied to the vibration signals and for change detection purposes, from signal processing point of view. The processed object is the time-frequency image (TFI), as result of the time-frequency transform.
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Frequency shift or intensity shift? The origin of spectral changes in vibrational spectra

Vibrational Spectroscopy, 2012
Abstract It has been shown that the frequency shift for a single band can be reconstructed by a linear combination of contributions from adjacent bands with fixed positions. Assuming discrete distribution of the peaks in a specified spectral range and an appropriate response function one can generate diverse patterns of spectral changes.
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Effect of a Change in Position of a Support on the Natural Frequencies and Modes of Vibration of a System

Journal of Mechanical Engineering Science, 1965
The effect of a small change in position of one of the supports on the natural frequencies and modes of a structure, which is ‘continuous’ over a number of supports, is examined in this paper. Using energy and receptance methods a simple formula is obtained for the change in natural frequency of a beam when the support displacement is infinitesimal ...
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Vaporization energy change and vibrational frequency shift in substituted mono-halo-benzenes

Theoretica Chimica Acta, 1970
Direct linear relation exists between the reduced vaporization energy change (ΔHv/RTB) of benzene and its homologues, C6H5X (X=F, Cl, Br, I) and the X-sensitive dimensionless frequency (hcv/kTB) at their respective normal boiling point (TB) temperatures.
J. Lielmezs, J. B. Butler, H. C. Henry, R. G. Orr   +3 more
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CHANGES IN THE NATURAL FREQUENCIES OF REPEATED MODE PAIRS INDUCED BY CRACKS IN A VIBRATING RING

Journal of Sound and Vibration, 1998
The presence of cracks in solid structures can be detected by measuring changes in the natural frequencies of appropriate vibration modes. In the present work a simple energy-based model of a vibrating ring is presented to estimate the effect of a crack on the frequencies of repeated mode pairs.
R.N. Wake, J.S. Burgess, J.T. Evans
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[Changes of vibration frequency due to root resorption of deciduous tooth].

Shoni shikagaku zasshi. The Japanese journal of pedodontics, 1992
The purpose of this study was to investigate the changes of vibration frequency of a deciduous tooth due to physiological root resorption. The author developed an analysis system for tooth vibration by applying an impact-hammer to the tooth. Peak frequency (Hz) of the tooth stimulated by the impact-hammer was observed by the analysis system.
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