Wideband frequency noise reduction in laser diodes using FM sideband technique and electronical feedback

2004 ◽  
Author(s):  
V. N. Barychev
Keyword(s):  
Noise Reduction ◽  
Laser Diodes ◽  
Frequency Noise

Numerical study on the airfoil self-noise of three owl-based wings with the trailing-edge serrations

2021 ◽  
pp. 095441002098822
Author(s):  
Dian Li ◽  
Xiaomin Liu ◽  
Lei Wang ◽  
Fujia Hu ◽  
Guang Xi
Keyword(s):  
Flow Field ◽  
Noise Reduction ◽  
Numerical Study ◽  
Barn Owl ◽  
Aerodynamic Noise ◽  
Frequency Noise ◽  
Trailing Edge ◽  
Reduction Mechanisms ◽  
Trailing Edge Serrations ◽  
Bionic Airfoil

Previous publications have summarized that three special morphological structures of owl wing could reduce aerodynamic noise under low Reynolds number flows effectively. However, the coupling noise-reduction mechanism of bionic airfoil with trailing-edge serrations is poorly understood. Furthermore, while the bionic airfoil extracted from natural owl wing shows remarkable noise-reduction characteristics, the shape of the owl-based airfoils reconstructed by different researchers has some differences, which leads to diversity in the potential noise-reduction mechanisms. In this article, three kinds of owl-based airfoils with trailing-edge serrations are investigated to reveal the potential noise-reduction mechanisms, and a clean airfoil based on barn owl is utilized as a reference to make a comparison. The instantaneous flow field and sound field around the three-dimensional serrated airfoils are simulated by using incompressible large eddy simulation coupled with the FW-H equation. The results of unsteady flow field show that the flow field of Owl B exhibits stronger and wider-scale turbulent velocity fluctuation than that of other airfoils, which may be the potential reason for the greater noise generation of Owl B. The scale and magnitude of alternating mean convective velocity distribution dominates the noise-reduction effect of trailing-edge serrations. The noise-reduction characteristic of Owl C outperforms that of Barn owl, which suggests that the trailing-edge serrations can suppress vortex shedding noise of flow field effectively. The trailing-edge serrations mainly suppress the low-frequency noise of the airfoil. The trailing-edge serration can suppress turbulent noise by weakening pressure fluctuation.

scholarly journals Shape Factors in Low‐Frequency Noise Reduction

1967 ◽  
Vol 42 (5) ◽  
pp. 1202-1203
Author(s):  
J. Ronald Bailey ◽  
Franklin D. Hart
Keyword(s):  
Noise Reduction ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Shape Factors

Application of a Helmholtz structure for low frequency noise reduction

2015 ◽  
Vol 63 (1) ◽  
pp. 20-35 ◽  
Author(s):  
Dong Guan ◽  
Jiu Hui Wu ◽  
Li Jing ◽  
Nansha Gao ◽  
Mingming Hou
Keyword(s):  
Noise Reduction ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise

Correlation between forward-reverse low-frequency noise and atypical I–V signatures in 980 nm high-power laser diodes

2015 ◽  
Vol 55 (9-10) ◽  
pp. 1741-1745 ◽  
Author(s):  
P. Del Vecchio ◽  
A. Curutchet ◽  
Y. Deshayes ◽  
M. Bettiati ◽  
F. Laruelle ◽  
...  
Keyword(s):  
High Power ◽  
Laser Diodes ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
High Power Laser ◽  
Power Laser

scholarly journals An improved time–frequency noise reduction method using a psycho-acoustic Mel model

2018 ◽  
Vol 79 ◽  
pp. 199-212 ◽  
Author(s):  
Samir Ouelha ◽  
Abdeldjalil Aïssa-El-Bey ◽  
Boualem Boashash
Keyword(s):  
Noise Reduction ◽  
Reduction Method ◽  
Frequency Noise ◽  
Time Frequency
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