Determination of optimal near‐field error sensor locations for active control of cooling fan noise using spherical harmonic expansions

2007 ◽  
Vol 121 (5) ◽  
pp. 3180-3180
Author(s):  
Benjamin M. Shafer ◽  
Kent L. Gee ◽  
Scott D. Sommerfeldt ◽  
J. Isaac Fjeldsted
Keyword(s):  
Active Control ◽  
Spherical Harmonic ◽  
Near Field ◽  
Fan Noise ◽  
Cooling Fan ◽  
Sensor Locations

Multi-channel active control of axial cooling fan noise

2002 ◽  
Vol 111 (5) ◽  
pp. 2453
Author(s):  
Kent L. Gee ◽  
Scott D. Sommerfeldt
Keyword(s):  
Active Control ◽  
Fan Noise ◽  
Cooling Fan

A compact active control implementation for axial cooling fan noise

2003 ◽  
Vol 51 (6) ◽  
pp. 325 ◽  
Author(s):  
Kent L. Gee ◽  
Scott D. Sommerfeldt
Keyword(s):  
Active Control ◽  
Fan Noise ◽  
Cooling Fan ◽  
Control Implementation

Application of acoustic analogy to automotive engine-cooling fan noise prediction

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 1095-1098 ◽  
Author(s):  
Jeonghan Lee ◽  
Kyungseok Cho ◽  
Soogab Lee
Keyword(s):  
Noise Prediction ◽  
Acoustic Analogy ◽  
Fan Noise ◽  
Automotive Engine ◽  
Engine Cooling ◽  
Cooling Fan

scholarly journals Evaluation of hydrological and cryospheric angular momentum estimates based on GRACE, GRACE-FO and SLR data for their contributions to polar motion excitation

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Justyna Śliwińska ◽  
Jolanta Nastula ◽  
Małgorzata Wińska
Keyword(s):  
Angular Momentum ◽  
Spherical Harmonic ◽  
Polar Motion ◽  
Spectral Band ◽  
Water Storage ◽  
Terrestrial Water Storage ◽  
Terrestrial Water ◽  
High Consistency ◽  
Polar Motion Excitation

AbstractIn geodesy, a key application of data from the Gravity Recovery and Climate Experiment (GRACE), GRACE Follow-On (GRACE-FO), and Satellite Laser Ranging (SLR) is an interpretation of changes in polar motion excitation due to variations in the Earth’s surficial fluids, especially in the continental water, snow, and ice. Such impacts are usually examined by computing hydrological and cryospheric polar motion excitation (hydrological and cryospheric angular momentum, HAM/CAM). Three types of GRACE and GRACE-FO data can be used to determine HAM/CAM, namely degree-2 order-1 spherical harmonic coefficients of geopotential, gridded terrestrial water storage anomalies computed from spherical harmonic coefficients, and terrestrial water storage anomalies obtained from mascon solutions. This study compares HAM/CAM computed from these three kinds of gravimetric data. A comparison of GRACE-based excitation series with HAM/CAM obtained from SLR is also provided. A validation of different HAM/CAM estimates is conducted here using the so-called geodetic residual time series (GAO), which describes the hydrological and cryospheric signal in the observed polar motion excitation. Our analysis of GRACE mission data indicates that the use of mascon solutions provides higher consistency between HAM/CAM and GAO than the use of other datasets, especially in the seasonal spectral band. These conclusions are confirmed by the results obtained for data from first 2 years of GRACE-FO. Overall, after 2 years from the start of GRACE-FO, the high consistency between HAM/CAM and GAO that was achieved during the best GRACE period has not yet been repeated. However, it should be remembered that with the systematic appearance of subsequent GRACE-FO observations, this quality can be expected to increase. SLR data can be used for determination of HAM/CAM to fill the one-year-long data gap between the end of GRACE and the start of the GRACE-FO mission. In addition, SLR series could be particularly useful in determination of HAM/CAM in the non-seasonal spectral band. Despite its low seasonal amplitudes, SLR-based HAM/CAM provides high phase consistency with GAO for annual and semiannual oscillation.

Determination of geometric properties of SNOM tips by means of combined far-field and near-field evaluation

1999 ◽  
Author(s):  
Soenke Seebacher ◽  
Wolfgang Osten ◽  
Werner P. O. Jueptner ◽  
Vadim P. Veiko ◽  
Nikolay B. Voznesensky
Keyword(s):  
Near Field ◽  
Field Evaluation ◽  
Far Field ◽  
Geometric Properties

Active control of fan noise

2008 ◽  
Vol 17 (2) ◽  
pp. 163-169 ◽  
Author(s):  
Nobuhiko Yamasaki ◽  
Hirotoshi Tajima
Keyword(s):  
Active Control ◽  
Fan Noise
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