Modeling Solar Oscillation Power Spectra. I. Adaptive Response Function for Doppler Velocity Measurements

2005 ◽  
Vol 623 (2) ◽  
pp. 1202-1214 ◽  
Author(s):  
Sergei V. Vorontsov ◽  
Stuart M. Jefferies
Keyword(s):  
Response Function ◽  
Adaptive Response ◽  
Power Spectra ◽  
Doppler Velocity ◽  
Solar Oscillation ◽  
Velocity Measurements ◽  
Oscillation Power

Modeling of solar oscillation power spectra

1990 ◽  
Vol 364 ◽  
pp. 699 ◽  
Author(s):  
Edwin R. Anderson ◽  
Thomas L., Jr. Duvall ◽  
Stuart M. Jefferies
Keyword(s):  
Power Spectra ◽  
Solar Oscillation ◽  
Oscillation Power

A Method for the Estimation of f- and p-mode Parameters and Rotational Splitting Coefficients from Un-averaged Solar Oscillation Power Spectra

2020 ◽  
Vol 894 (1) ◽  
pp. 80
Author(s):  
J. Reiter ◽  
E. J. Rhodes ◽  
A. G. Kosovichev ◽  
P. H. Scherrer ◽  
T. P. Larson ◽  
...  
Keyword(s):  
Power Spectra ◽  
Solar Oscillation ◽  
Oscillation Power

scholarly journals A METHOD FOR THE ESTIMATION OF $p$-MODE PARAMETERS FROM AVERAGED SOLAR OSCILLATION POWER SPECTRA

2015 ◽  
Vol 803 (2) ◽  
pp. 92 ◽  
Author(s):  
J. Reiter ◽  
E. J. Rhodes Jr. ◽  
A. G. Kosovichev ◽  
J. Schou ◽  
P. H. Scherrer ◽  
...  
Keyword(s):  
Power Spectra ◽  
Solar Oscillation ◽  
Oscillation Power

Studies on Noise and Flow Fields in a Squirrel Cage Fan

Volume 1 ◽  
2004 ◽  
Author(s):  
Nader Montazerin ◽  
Abraham Damangir ◽  
Mohammad H. Hessami Azizi
Keyword(s):  
Power Level ◽  
Power Spectra ◽  
Maximum Flow ◽  
Doppler Velocity ◽  
Velocity Measurements ◽  
Squirrel Cage ◽  
Unsteady Fluid Flow ◽  
White Band ◽  
Noise Measurements ◽  
Unsteady Fluid

There is a wide application of squirrel cage fan in heating and ventilating systems where a reduction of noise with fluid mechanics origin is of importance. This paper presents an aero-acoustic study on a squirrel-cage fan and the relation between unsteady fluid flow and the noise generated in the fan is investigated. Noise measurements in the exit channel of a fan are presented together with laser Doppler velocity measurements outside the rotor. Both measurements are Fourier transformed and important frequency contents are analyzed. Velocity measurements show that the largest fluctuations happen just after the inlet and close to the cut-off. The power spectra of velocity components near the rotor inlet and the cut off are high in comparison with other circumferential and axial positions. Blade passing frequency is dominant in noise and velocity data with a considerable volume of white band noise. It is not present at locations with no flow through the rotor. Fan performance and noise are available for different inlet geometries. An optimization of the inlet configuration changed the maximum flow rate but the sound power level was similar at the same volumetric flow regardless of the inlet shape.

Power Spectra Density Replication Control Strategy for 2-Axis Hydraulic Shaker Based on HV Estimator

2014 ◽  
Vol 596 ◽  
pp. 610-615
Author(s):  
Yu Chen ◽  
Qiang Li Luan ◽  
Zhang Wei Chen ◽  
Hui Nong He
Keyword(s):  
Response Function ◽  
Control Algorithm ◽  
Power Spectra ◽  
Time History ◽  
Good Effect ◽  
System Response ◽  
Power Spectral ◽  
Iterative Correction ◽  
Replication Control ◽  
The Given

Hydraulic shaker, equipment of simulating laboratory vibration environment, can accurately replicate the given power spectral density (PSD) and time history with an appropriate control algorithm. By studying method Hv estimator of frequency response function (FRF) estimation, a FRF identification strategy based on the Hv estimator is designed to increase the convergence rapidity and improve the system response function specialty. The system amplitude-frequency characteristics in some frequency points or frequency bands have large fluctuation. To solve this issue, a step-varying and frequency-sectioning iterative correction control algorithm is proposed for the control of 2-axial exciter PSD replication tests and the results show that the algorithm has a good effect on the control of hydraulic shaker, and can achieve reliable and high-precision PSD replication.

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