Wind farm noise propagation and viable noise reduction strategies

2021 ◽  
pp. 213-226
Keyword(s):  
Noise Reduction ◽  
Wind Farm ◽  
Noise Propagation ◽  
Reduction Strategies

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.

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.

Noise reduction of pile driving and unexploded ordinance detonations at offshore wind farm installation sites

2017 ◽  
Vol 141 (5) ◽  
pp. 3847-3847
Author(s):  
Mark S. Wochner ◽  
Kevin M. Lee ◽  
Andrew R. McNeese ◽  
Preston S. Wilson
Keyword(s):  
Noise Reduction ◽  
Wind Farm ◽  
Offshore Wind ◽  
Pile Driving ◽  
Offshore Wind Farm ◽  
Unexploded Ordinance

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 Modelling installed jet noise due to the scattering of jet instability waves by swept wings

2019 ◽  
Vol 870 ◽  
pp. 760-783 ◽  
Author(s):  
Benshuai Lyu ◽  
Ann P. Dowling
Keyword(s):  
Noise Reduction ◽  
Physical Mechanism ◽  
Jet Noise ◽  
Destructive Interference ◽  
Sweep Angle ◽  
Low Frequencies ◽  
Instability Waves ◽  
Jet Instability ◽  
Reduction Strategies ◽  
Swept Wings

Jet noise is a significant contributor to aircraft noise, and on modern aircraft it is considerably enhanced at low frequencies by a closely installed wing. Recent research has shown that this noise increase is due to the scattering of jet instability waves by the trailing edge of the wing. Experimentalists have recently shown that noise can be reduced by using wings with swept trailing edges. To understand this mechanism, in this paper, we develop an analytical model to predict the installed jet noise due to the scattering of instability waves by a swept wing. The model is based on the Schwarzschild method and Amiet’s approach is used to obtain the far-field sound. The model can correctly predict both the reduction in installed jet noise and the change to directivity patterns observed in experiments due to the use of swept wings. The agreement between the model and experiment is very good, especially for the directivity at large azimuthal angles. It is found that the principal physical mechanism of sound reduction is due to destructive interference. It is concluded that in order to obtain an effective noise reduction, both the span and the sweep angle of the wing have to be large. Such a model can greatly aid in the design of quieter swept wings and the physical mechanism identified can provide significant insight into developing other innovative noise-reduction strategies.

The Hospital (Not So) Quiet Zone: Creating an Environment for Patient Satisfaction Through Noise Reduction Strategies

2019 ◽  
Vol 12 (4) ◽  
pp. 197-202 ◽  
Author(s):  
Linda Walker ◽  
Cherry A. Karl
Keyword(s):  
Patient Satisfaction ◽  
Noise Reduction ◽  
Visual Cues ◽  
Online Survey ◽  
Well Being ◽  
Hospital Environment ◽  
Noise Levels ◽  
Telephone Interviews ◽  
Patient Surveys ◽  
Reduction Strategies

Purpose:To determine whether using existing noise reduction strategies improves patients’ overall satisfaction level during hospitalization on an adult outpatient cardiology unit and to assess whether noise reduction strategies were effective to decrease the ambient noise for both staff and patient environments.Background:Excessive noise is a worldwide problem facing hospitals today. Noise has been proven to be detrimental to staff and patient well-being and hospital environment satisfaction levels.Intervention:Staff noise perception online surveys, a poster presentation, and education of noise reduction strategies were completed. Two 6-week phases of pre- and postimplementation noise reduction strategies were initiated including closing of the doors, verbal and visual alarm reminders for staff, posting quiet signs, and limiting equipment through the unit. Patient telephone interviews regarding the noise environment during hospitalization in both phases and a follow-up staff noise perception online survey were completed.Results:Staff surveys identified noise as an issue on the unit with staff communication (90%) being the main source. This correlated with patient surveys of five rooms closest to the desk considering the unit “noisy.” Post-implementation patient surveys noted that strategies created in helping the unit become “quiet/mostly quiet.” Closing patient doors was most effective in noise reduction, increasing patient unit satisfaction.Conclusion:The use of visual cues and staff education are effective in reducing noise levels. Decreased noise levels improved overall patient satisfaction with their hospital experience and created a less stressful work environment.

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