Nascent Noise Reduction Strategies for Underwater Vehicles

Volume 1 ◽  
2004 ◽  
Author(s):  
Promode R. Bandyopadhyay
Keyword(s):  
Noise Reduction ◽  
Artificial Muscle ◽  
Underwater Vehicles ◽  
Drive Train ◽  
Forward Speed ◽  
High Lift ◽  
Radiated Noise ◽  
Rotational Rate ◽  
Reduction Strategies

Noise reduction concepts applicable to small underwater vehicles and in the nascent stages of research, are considered. These questions are asked. How to lower the propulsor rotational rate while maintaining forward speed? How to reduce blade tonal? How to supplant the propulsor drive train, which is the main source of hull vibration and radiated noise? The highlights of progress in passive and active approaches are reviewed. The approaches are inspired by unsteady high lift principles employed in flying and swimming animals and by emerging artificial muscle technology.

scholarly journals Aeroacoustics of Silent Owl Flight

2020 ◽  
Vol 52 (1) ◽  
pp. 395-420 ◽  
Author(s):  
Justin W. Jaworski ◽  
N. Peake
Keyword(s):  
Mathematical Modeling ◽  
Noise Reduction ◽  
Current Knowledge ◽  
Foraging Strategies ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
Reduction Strategies ◽  
Noise Measurements ◽  
Modeling And Experiments ◽  
Review Current

The ability of some species of owl to fly in effective silence is unique among birds and provides a distinct hunting advantage, but it remains a mystery as to exactly what aspects of the owl and its flight are responsible for this dramatic noise reduction. Crucially, this mystery extends to how the flow physics may be leveraged to generate noise-reduction strategies for wider technological application. We review current knowledge of aerodynamic noise from owls, ranging from live owl noise measurements to mathematical modeling and experiments focused on how owls may disrupt the standard routes of noise generation. Specialized adaptations and foraging strategies are not uniform across all owl species: Some species may not have need for silent flight, or their evolutionary adaptations may not be effective for useful noise reduction for certain species. This hypothesis is examined using mathematical models and borne out where possible by noise measurements and morphological observations of owl feathers and wings.

Experimentation and Computational Assessment of an SMA-Based Slat-Cove Filler For Noise Reduction in a High Lift Wing

2017 ◽  
Author(s):  
William D. Scholten ◽  
Ryan Patterson ◽  
Quentin Chapelon ◽  
Darren J. Hartl ◽  
Thomas W. Strganac ◽  
...  
Keyword(s):  
Noise Reduction ◽  
High Lift

Radiated Noise Reduction in a Single Cylinder Direct Injection (DI) Naturally Aspirated (NA) Engine

2011 ◽  
Author(s):  
Sudhakara Naidu T ◽  
Chaitanya Krishna Balla ◽  
Chris carlson ◽  
David Hudson
Keyword(s):  
Noise Reduction ◽  
Direct Injection ◽  
Single Cylinder ◽  
Radiated Noise

scholarly journals Noise Reduction in an Intensive Care Unit: Implementation of Quiet Time and Noise-Reduction Strategies

2020 ◽  
Author(s):  
Poonam Gupta ◽  
Mincy Shaji ◽  
Aisha Amer ◽  
Sherin Joseph ◽  
Ivy Louis ◽  
...  
Keyword(s):  
Intensive Care ◽  
Noise Reduction ◽  
Noise Level ◽  
Physical Therapists ◽  
Excess Noise ◽  
Quality Improvement Initiative ◽  
Quiet Time ◽  
Qualitative Feedback ◽  
Reduction Strategies ◽  
Recommended Level

Abstract Background: Excessive noise is a significant problem for patients in intensive care units (ICUs) and is associated with significant psychological effects and the potential to affect patient outcomes. The noise level in our coronary care intensive unit of a cardiac hospital was found to be approximately 80 dB, which exceeded the international recommended level of 35 dB. We sought to review the causes of this excess noise and the effects of an implementation of quiet time and a noise-reduction bundle in the ICU.Methods: A quality improvement initiative was undertaken to solve the noise issue. A multi-disciplinary team was formed and a number of changes were tested. We used a model for improvement, and the changes were tested using small Plan-Do-Study-Act cycles. Two blocks of quiet time (3-4 pm and 2-4 am) were designated as quiet times during which the lights were dimmed, noise-reduction strategies in the form of a bundle were implemented, and procedures were minimized. In addition, educational material and information were disseminated to physicians, nurses, physical therapists, and other potential individuals who might be affected by the changes that were implemented. Quantitative baseline data was collected using sound meter readings three times a day. Qualitative feedback was collected through staff and patient surveys.Results: During quiet hours, the noise level averaged 22 dB—a decrease from 85 dB. One-hundred patients were surveyed and asked for their feedback concerning quiet time: approximately 97% of them were satisfied with the results.Conclusions: It is possible to reduce noise levels in ICUs by implementing simple and effective measures. This reduction has a significant effect on patient satisfaction, and, in addition, promotes healing.

scholarly journals Layout Method of Damping Material for Gearbox Based on Acoustic Contribution

2019 ◽  
Vol 37 (4) ◽  
pp. 757-766
Author(s):  
Yunong Liu ◽  
Lan Liu ◽  
Geng Liu ◽  
Liyan Wu ◽  
Chao Liu ◽  
...  
Keyword(s):  
Noise Reduction ◽  
Present Method ◽  
Element Model ◽  
Low Noise ◽  
Radiated Noise ◽  
Damping Material ◽  
Plate Area ◽  
Acoustic Contribution ◽  
Reduction Effect ◽  
Damping Materials

In order to realize the low noise design of marine gearbox, a layout method of damping materials for gearbox based on acoustic contribution was proposed. The present method can accurately and effectively determine the additional area of damping materials and achieve greatly the noise reduction effect. Firstly, taking a marine single-stage herringbone gearbox as the object, the finite element/boundary element model for the reducer structure was established. After applying the vibration excitation of the gear system, the radiated noise of each field point was solved. Secondly, by analyzing the acoustic transfer vector (ATV) and modal acoustic contribution (MAC), the surface of the gearbox was partitioned, and the partitioned surface was analyzed by using panel acoustic contribution (PAC). Finally, the damping material was added to the plate area which contributes greatly to the radiated noise, and the effect of the noise reduction under different schemes were compared. The results show that the layout design of damping materials based on the present method can reduce the radiation noise of observation points accurately and effectively in the range of 0~4 000 Hz.

scholarly journals Composite cylinder cross section tailoring for radiated noise reduction

1993 ◽  
Vol 94 (3) ◽  
pp. 1839-1839
Author(s):  
Colin P. Ratcliffe ◽  
Roger M. Crane ◽  
Armando L. Santiago
Keyword(s):  
Noise Reduction ◽  
Cross Section ◽  
Composite Cylinder ◽  
Radiated Noise
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