An offline roughness evaluation software and its application in quantitative calculation of wiggling based on low frequency Power Spectral Density method

2017 ◽  
Author(s):  
Libin Zhang ◽  
Lisong Dong ◽  
Xiaojing Su ◽  
Yansong Liu ◽  
Lijun Zhao ◽  
...  
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Low Frequency ◽  
Density Method ◽  
Quantitative Calculation ◽  
Power Spectral ◽  
Roughness Evaluation ◽  
Low Frequency Power ◽  
Spectral Density Method ◽  
Frequency Power

Increase in electromyogram low-frequency power in nonfatigued contracting skeletal muscle

1986 ◽  
Vol 61 (3) ◽  
pp. 1012-1017 ◽  
Author(s):  
A. R. Bazzy ◽  
J. B. Korten ◽  
G. G. Haddad
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Biceps Brachii ◽  
Low Frequency ◽  
Biceps Brachii Muscle ◽  
Power Spectral ◽  
Loaded Breathing ◽  
Low Frequency Power ◽  
The Relationship ◽  
Frequency Power

We studied the relationship between changing elbow joint angle and the power spectral density of the biceps brachii muscle electromyogram (EMG) during submaximal isometric contractions. For this purpose, we recorded the EMG of the biceps brachii muscle with surface electrodes in 13 subjects. Each subject held a 2.8-kg weight and contracted the biceps isometrically for 30 s at one of two lengths. The length of the muscle was changed by flexing the forearm toward the upper arm to form an angle of 135 degrees (L1) or 45 degrees (L2). We found that the mean centroid frequency (fc) of the EMG power spectral density was 26% lower at L1 than at L2 (P less than 0.01). For each subject there was no significant change in fc during the isometric contraction at either angle. In addition, in nine subjects who sustained fatiguing contractions of the biceps with a 6-kg load, fc decreased by 15% (P less than 0.025). These data suggest that a change in the length at which a muscle contracts isometrically can alter or induce indirectly an alteration in the frequency content of its EMG. This finding may have important implications for the assessment of respiratory muscle EMG especially during loaded breathing.

Analysis of turbulence power spectra and velocity correlations in a pipeline with obstructions

2017 ◽  
Vol 28 (02) ◽  
pp. 1750019 ◽  
Author(s):  
A. T. da Cunha Lima ◽  
I. C. da Cunha Lima ◽  
M. P. de Almeida
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Cross Sections ◽  
Power Spectra ◽  
Low Frequency ◽  
Frequency Range ◽  
Frequency Space ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Low Frequency Power

We calculate the power spectral density and velocity correlations for a turbulent flow of a fluid inside a duct. Turbulence is induced by obstructions placed near the entrance of the flow. The power spectral density is obtained for several points at cross-sections along the duct axis, and an analysis is made on the way the spectra changes according to the distance to the obstruction. We show that the differences on the power spectral density are important in the lower frequency range, while in the higher frequency range, the spectra are very similar to each other. Our results suggest the use of the changes on the low frequency power spectral density to identify the occurrence of obstructions in pipelines. Our results show some frequency regions where the power spectral density behaves according to the Kolmogorov hypothesis. At the same time, the calculation of the power spectral densities at increasing distances from the obstructions indicates an energy cascade where the spectra evolves in frequency space by spreading the frequency amplitude.

Calibration of Stiffness of Optical Tweezers in Three Dimensions with Power Spectral Density Method

2014 ◽  
Vol 43 (5) ◽  
pp. 535001
Author(s):  
梁言生 LIANG Yan-sheng ◽  
姚保利 YAO Bao-li ◽  
雷铭 LEI Ming ◽  
于湘华 YU Xiang-hua ◽  
严绍辉 YAN Shao-hui ◽  
...  
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Optical Tweezers ◽  
Three Dimensions ◽  
Density Method ◽  
Power Spectral ◽  
Spectral Density Method
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