Experimental validation of a diffraction correction model for high frequency measurement of ultrasound backscatter coefficients

Author(s):  
J.C. Machado ◽  
F.S. Foster
2014 ◽  
Vol 40 (1) ◽  
pp. 244-257 ◽  
Author(s):  
Nils Männicke ◽  
Martin Schöne ◽  
Matthias Gottwald ◽  
Felix Göbel ◽  
Michael L. Oelze ◽  
...  

2015 ◽  
Vol 12 (3) ◽  
pp. 303-320
Author(s):  
Miloje Kostic

On the basis of the known fact that all air gap main flux density variations are enclosed by permeance slot harmonics, only one component of stray losses in rotor (stator) iron is considered in the new classification, instead of 2 components: rotor (stator) pulsation iron losses, and rotor (stator) surface iron losses. No-load rotor cage (high-frequency) stray losses are usually calculated. No-load stray losses are caused by the existence of space harmonics: the air-gap slot permeance harmonics and the harmonics produced by no-load MMF harmonics. The second result is the proof that the corresponding components of stray losses can be calculated separately for the mentioned kind of harmonics. Determination of the depth of flux penetration and calculations of high frequency iron losses are improved. On the basis of experimental validation, it is proved that the new classification of no-load stray losses and the proposed method for the calculation of the total value is sufficiently accurate.


2020 ◽  
Author(s):  
Pieter-Jan Daems ◽  
Y. Guo ◽  
S. Sheng ◽  
C. Peeters ◽  
P. Guillaume ◽  
...  

Abstract Wind energy is one of the largest sources of renewable energy in the world. To further reduce the operations and maintenance (O&M) costs of wind farms, it is essential to be able to accurately pinpoint the root causes of different failure modes of interest. An example of such a failure mode that is not yet fully understood is white etching cracks (WEC). This can cause the bearing lifetime to be reduced to 5–10% of its design value. Multiple hypotheses are available in literature concerning its cause. To be able to validate or disprove these hypotheses, it is essential to have historic high-frequency measurement data (e.g., load and vibration levels) available. In time, this will allow linking to the history of the turbine operating data with failure data. This paper discusses the dynamic loading on the turbine during certain events (e.g., emergency stops, run-ups, and during normal operating conditions). By combining the number of specific events that each turbine has seen with the severity of each event, it becomes possible to assess which turbines are most likely to show signs of damage.


2018 ◽  
Vol 18 (13) ◽  
pp. 5238-5244 ◽  
Author(s):  
Andrew Feeney ◽  
Lei Kang ◽  
Steve Dixon

Author(s):  
Arianto Budi Santoso ◽  
Endra Triwisesa ◽  
Muh. Fakhrudin ◽  
Eko Harsono ◽  
Hadiid Agita Rustini

1990 ◽  
Vol 5 (1) ◽  
pp. 41-53 ◽  
Author(s):  
V.J. Thottuvelil ◽  
T.G. Wilson ◽  
H.A. Owen

Sign in / Sign up

Export Citation Format

Share Document