Flow noise reduction techniques for a planar array of hydrophones

1992 ◽  
Vol 92 (6) ◽  
pp. 3409-3424 ◽  
Author(s):  
Sung H. Ko ◽  
Howard H. Schloemer
Keyword(s):  
Noise Reduction ◽  
Flow Noise ◽  
Reduction Techniques ◽  
Planar Array

scholarly journals Flow noise reduction techniques for a planar array of hydrophones.

1991 ◽  
Vol 90 (4) ◽  
pp. 2285-2285 ◽  
Author(s):  
Sung H. Ko ◽  
Howard H. Schloemer
Keyword(s):  
Noise Reduction ◽  
Flow Noise ◽  
Reduction Techniques ◽  
Planar Array

scholarly journals Noise Reduction Effect of Superhydrophobic Surfaces with Streamwise Strip of Channel Flow

2021 ◽  
Vol 11 (9) ◽  
pp. 3869
Author(s):  
Chen Niu ◽  
Yongwei Liu ◽  
Dejiang Shang ◽  
Chao Zhang
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
Noise Reduction ◽  
Channel Flow ◽  
Superhydrophobic Surface ◽  
Sound Field ◽  
Flow Noise ◽  
Slip Boundary ◽  
Eddy Simulation ◽  
Reduction Effect

Superhydrophobic surface is a promising technology, but the effect of superhydrophobic surface on flow noise is still unclear. Therefore, we used alternating free-slip and no-slip boundary conditions to study the flow noise of superhydrophobic channel flows with streamwise strips. The numerical calculations of the flow and the sound field have been carried out by the methods of large eddy simulation (LES) and Lighthill analogy, respectively. Under a constant pressure gradient (CPG) condition, the average Reynolds number and the friction Reynolds number are approximately set to 4200 and 180, respectively. The influence on noise of different gas fractions (GF) and strip number in a spanwise period on channel flow have been studied. Our results show that the superhydrophobic surface has noise reduction effect in some cases. Under CPG conditions, the increase in GF increases the bulk velocity and weakens the noise reduction effect. Otherwise, the increase in strip number enhances the lateral energy exchange of the superhydrophobic surface, and results in more transverse vortices and attenuates the noise reduction effect. In our results, the best noise reduction effect is obtained as 10.7 dB under the scenario of the strip number is 4 and GF is 0.5. The best drag reduction effect is 32%, and the result is obtained under the scenario of GF is 0.8 and strip number is 1. In summary, the choice of GF and the number of strips is comprehensively considered to guarantee the performance of drag reduction and noise reduction in this work.

scholarly journals Feasibility of Total Variation Noise Reduction Algorithm According to Various MR-Based PET Images in a Simultaneous PET/MR System: A Phantom Study

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 319
Author(s):  
Chan-Rok Park ◽  
Seong-Hyeon Kang ◽  
Young-Jin Lee
Keyword(s):  
Image Quality ◽  
Noise Reduction ◽  
Total Variation ◽  
Parallel Imaging ◽  
Pulse Sequence ◽  
Reduction Algorithm ◽  
Median Filters ◽  
Reduction Techniques ◽  
Imaging Results ◽  
Noise Reduction Algorithm

Recently, the total variation (TV) algorithm has been used for noise reduction distribution in degraded nuclear medicine images. To acquire positron emission tomography (PET) to correct the attenuation region in the PET/magnetic resonance (MR) system, the MR Dixon pulse sequence, which is based on controlled aliasing in parallel imaging, results from higher acceleration (CAIPI; MR-ACDixon-CAIPI) and generalized autocalibrating partially parallel acquisition (GRAPPA; MR-ACDixon-GRAPPA) algorithms are used. Therefore, this study aimed to evaluate the image performance of the TV noise reduction algorithm for PET/MR images using the Jaszczak phantom by injecting 18F radioisotopes with PET/MR, which is called mMR (Siemens, Germany), compared with conventional noise-reduction techniques such as Wiener and median filters. The contrast-to-noise (CNR) and coefficient of variation (COV) were used for quantitative analysis. Based on the results, PET images with the TV algorithm were improved by approximately 7.6% for CNR and decreased by approximately 20.0% for COV compared with conventional noise-reduction techniques. In particular, the image quality for the MR-ACDixon-CAIPI PET image was better than that of the MR-ACDixon-GRAPPA PET image. In conclusion, the TV noise-reduction algorithm is efficient for improving the PET image quality in PET/MR systems.

scholarly journals Methods for Clinical Evaluation of Noise Reduction Techniques in Abdominopelvic CT

Radiographics ◽  
2014 ◽  
Vol 34 (4) ◽  
pp. 849-862 ◽  
Author(s):  
Eric C. Ehman ◽  
Lifeng Yu ◽  
Armando Manduca ◽  
Amy K. Hara ◽  
Maria M. Shiung ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Clinical Evaluation ◽  
Reduction Techniques ◽  
Abdominopelvic Ct

Theoretical Analysis of Binaural Multimicrophone Noise Reduction Techniques

2010 ◽  
Vol 18 (2) ◽  
pp. 342-355 ◽  
Author(s):  
B. Cornelis ◽  
S. Doclo ◽  
T. Van dan Bogaert ◽  
M. Moonen ◽  
J. Wouters
Keyword(s):  
Theoretical Analysis ◽  
Noise Reduction ◽  
Reduction Techniques

scholarly journals Noise Reduction Techniques for Close-fitting Enclosures at Structural/Acoustic Resonance

2003 ◽  
Vol 46 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Yiu Yin LEE ◽  
Kwok Kit YUEN ◽  
Ka Chi LAM ◽  
Heung Fai LAM
Keyword(s):  
Noise Reduction ◽  
Acoustic Resonance ◽  
Reduction Techniques

Research on acoustic behaviors of water pipelines with guide vanes

2022 ◽  
pp. 107754632110623
Author(s):  
Xianzhong Wang ◽  
Ning Li ◽  
Min Yu ◽  
Hongzhou Lin ◽  
Lili Ye
Keyword(s):  
Noise Reduction ◽  
Guide Vane ◽  
Experimental Methods ◽  
Guide Vanes ◽  
Experimental Platform ◽  
Flow Noise ◽  
Water Pipelines ◽  
Flow Speeds ◽  
Radiation Noise ◽  
Reduction Effect

In this paper, the pipeline with guide vanes was taken as the research object, the flow noise was studied based on the hybrid calculation method, then the acoustic-structure coupling method was introduced to study the vibration and radiation noise, and then explored the best position of the guide vanes. Based on the pipeline experimental platform and improved experimental methods, it was found that the guide vanes had a better noise reduction effect on the elbows; based on that, a simulation study was carried out on the elbow with guide vanes, and the mechanism of the guide vanes on the velocity field and pulsating pressure of the pipeline was explored. Finally, the noise reduction effect at different positions of the guide vanes under different flow speeds was studied. The results indicated that the guide vane at the middle of the elbow had the best effect on improving the flow field and reducing noise in the working conditions studied in this article, providing a calculation basis for the design of the guide vane.

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