The position shifting of frequency spectrum of Fourier transform in the application of aspheric surface testing

2007 ◽  
Author(s):  
Junmiao Weng ◽  
Yongying Yang ◽  
Dong Liu ◽  
Yibing Shen ◽  
Yongmo Zhuo
Keyword(s):  
Fourier Transform ◽  
Frequency Spectrum ◽  
Aspheric Surface ◽  
Surface Testing

Research on Shearer Rocker Gearbox Fault Location Based on Wavelet Envelope Demodulation

2014 ◽  
Vol 528 ◽  
pp. 210-216
Author(s):  
Zeng Qiang Wang ◽  
Hong Wei Ma ◽  
Mei Hua Tao ◽  
Xu Hui Zhang ◽  
Qing Hua Mao
Keyword(s):  
Fourier Transform ◽  
Frequency Spectrum ◽  
Spectrum Analysis ◽  
Fault Location ◽  
Vibration Signal ◽  
Morlet Wavelet ◽  
Frequency Spectrum Analysis ◽  
Mechanical Faults ◽  
Faults Diagnosis ◽  
Feature Frequency

To solve the problem of faults location for shearer rocker gearbox, the multiple sites vibration signal of faulty rocker gearbox are collected, as well as the Morlet wavelet envelope demodulation is applied to demodulate vibration signal and Fourier transform is used to carry out frequency spectrum analysis of vibration signal. Experimental results show that this method can effectively extract the faults feature frequency from complex vibration signal. The faults location result is consistent with actual faults part. This mean realizes to locate faults accurately. It provides an effective method for mechanical faults diagnosis of shearer.

Design and Error Analysis of the Computer-Generated Helogram Used for Concave Aspheric Surface Testing

2012 ◽  
Vol 49 (11) ◽  
pp. 110902
Author(s):  
冯婕 Feng Jie ◽  
邓超 Deng Chao ◽  
邢廷文 Xing Tingwen
Keyword(s):  
Error Analysis ◽  
Aspheric Surface ◽  
Surface Testing

scholarly journals Fringe interpreting for aspheric surface testing.

1991 ◽  
Vol 57 (4) ◽  
pp. 646-651 ◽  
Author(s):  
Norimichi TSUMURA ◽  
Takashi YAMAMOTO ◽  
Kunikazu OHNISHI ◽  
Shunsuke YOKOZEKI
Keyword(s):  
Aspheric Surface ◽  
Surface Testing

scholarly journals Investigation of the characteristics of geoelectric field signals prior to earthquakes using adaptive STFT techniques

2013 ◽  
Vol 13 (6) ◽  
pp. 1679-1686 ◽  
Author(s):  
W. Astuti ◽  
W. Sediono ◽  
R. Akmeliawati ◽  
A. M. Aibinu ◽  
M. J. E. Salami
Keyword(s):  
Spectral Analysis ◽  
Fourier Transform ◽  
Natural Disasters ◽  
Detailed Analysis ◽  
Frequency Spectrum ◽  
Earthquake Prediction ◽  
Geoelectric Field ◽  
Short Time Fourier Transform ◽  
Large Material ◽  
Short Time

Abstract. An earthquake is one of the most destructive natural disasters that can occur, often killing many people and causing large material losses. Hence, the ability to predict earthquakes may reduce the catastrophic effects caused by this phenomenon. The geoelectric field is a feature that can be used to predict earthquakes (EQs) because of significant changes in the amplitude of the signal prior to an earthquake. This paper presents a detailed analysis of geoelectric field signals of earthquakes which occurred in 2008 in Greece. In 2008, 12 earthquakes occurred in Greece. Five of them were recorded with magnitudes greater than Ms = 5R (5R), while seven of them were recorded with magnitudes greater than Ms = 6R (6R). In the analysis, the 1st significant changes of the geoelectric field signal are detected. Then, the signal is segmented and windowed. The adaptive short-time Fourier transform (adaptive STFT) technique is then applied to the windowed signal, and the spectral analysis is performed thereafter. The results show that the 1st significant changes of the geoelectric field prior to an earthquake have a significant amplitude frequency spectrum compared to other conditions, i.e. normal days and the day of the earthquake, which can be used as input parameters for earthquake prediction.

Design and fabrication of CGH for aspheric surface testing and its experimental comparison with null lens

2010 ◽  
Author(s):  
Fazhi Li ◽  
Jingli Zhao ◽  
Ruigang Li ◽  
Binzhi Zhang ◽  
Ligong Zheng ◽  
...  
Keyword(s):  
Experimental Comparison ◽  
Aspheric Surface ◽  
Surface Testing

Application of irradiance transport equation in aspheric surface testing

Optik ◽  
2012 ◽  
Vol 123 (14) ◽  
pp. 1282-1286 ◽  
Author(s):  
Ramin Shomali ◽  
Ahmad Darudi ◽  
Sadollah Nasiri
Keyword(s):  
Transport Equation ◽  
Aspheric Surface ◽  
Surface Testing

ORIGINATIONS AND EXTINCTIONS: ANALYSES OF FOSSIL DATA AND SIMULATIONS

2000 ◽  
Vol 11 (02) ◽  
pp. 277-285 ◽  
Author(s):  
TANE RAY ◽  
LEO MOSELEY ◽  
NAEEM JAN
Keyword(s):  
Fourier Transform ◽  
Frequency Dependence ◽  
Frequency Spectrum ◽  
Fossil Record ◽  
Trophic Levels ◽  
The Other ◽  
Simulation Data ◽  
The Past ◽  
Other Hand ◽  
Fossil Data

We analyse the fossil data of Benton1 with and without interpolation schemes. By Fourier transform analysis, we find a frequency dependence of the amplitude of 1/f for the various interpolation schemes used in the past. We illustrate that shuffling the interpolated data changes the spectra only slightly. On the other hand, an identical analysis performed on the raw (uninterpolated) fossil data gives a flat frequency spectrum. We conclude that the 1/f behavior is an artifact of the interpolation schemes. We next introduce a simulation of extinctions driven only by interactions between two trophic levels. Fourier transform analysis of the simulation data shows a frequency dependence of 1/f. When the data are grouped into a form resembling the fossil record the frequency dependence vanishes, giving a flat spectrum. Our simulation produces a frequency spectrum that agrees with the observed fossil record.

Virtual testing technique applied in aspheric surface testing

2002 ◽  
Author(s):  
Mengxia Liu ◽  
Huilan Liu ◽  
Jun Li ◽  
Dingguo Sha
Keyword(s):  
Aspheric Surface ◽  
Testing Technique ◽  
Virtual Testing ◽  
Surface Testing
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