Improving single flyover noise prediction for subsonic aircraft

2021 ◽  
Vol 263 (3) ◽  
pp. 3259-3270
Author(s):  
Oleksandr Zaporozhets ◽  
Alexandras Jagniatinskis
Keyword(s):  
Statistical Data ◽  
Sound Propagation ◽  
Ground Effect ◽  
Directivity Pattern ◽  
General View ◽  
Essential Difference ◽  
Noise Levels ◽  
Sound Levels ◽  
Effect Model ◽  
Flight Parameters

Current ICAO Doc 9911 provides the algorithm to calculate aircraft noise levels for any kind of airport flight scenario. The essential difference exists between the measured and calculated sound levels, especially for single flight noise events. Doc 9911 recommends using this method for equivalent sound levels L and noise indices L first of all. A number of national noise regulations still require for single noise event assessment. An article analyzes a number of reasons to explain the inaccuracy of noise event calculations. For example, the differences between calculated balanced flight parameters (thrust and velocity first of all) and supervised in real flights may influence the accuracy first of all. Statistical data was gathered to make more general view on these differences and some proposal to use them in calculations has being proved. Also, the assumptions of the ICAO Doc 9911 method may contribute to the inaccuracy of calculations. Among them are the homogeneous atmosphere for sound propagation, generalized for overall fleet noise directivity pattern, etc. Ground effect model defines the values for aircraft absent in operation currently. The first assumption provides a conflict with flight path calculations for varied atmosphere parameters with height over the surface.

scholarly journals 303 What goes bump in the night? A literature review and noise exposure experiment in a UK paediatric emergency department

2020 ◽  
Vol 37 (12) ◽  
pp. 841.1-841
Author(s):  
Lucy Hall ◽  
Sophie Dando ◽  
Anthony Hanks
Keyword(s):  
Emergency Department ◽  
Literature Review ◽  
Literature Search ◽  
Noise Exposure ◽  
Cochrane Library ◽  
Noise Levels ◽  
Paediatric Emergency Department ◽  
Paediatric Emergency ◽  
Sound Levels ◽  
Exposure Experiment

Aims/Objectives/BackgroundIn the Emergency department (ED), noise is a frequent and often unavoidable consequence of work undertaken and levels can often be raised during the day and night. Raised ambient noise levels have potential implications for the workforce, patients and relatives.Investigation into the problem of noise levels in the ED follows feedback from a young patient who couldn’t sleep during a prolonged stay. His complaint focused on loud, irregular banging noises such as those from closing bins that kept him awake.The team felt work should be done to see if it was a wider spread problem or just isolated to his case. A simple sound recording experiment and literature search was conducted.Methods/DesignThe literature search was conducted using electronic/online databases (Medline; Cochrane library) with a fixed date range and specific inclusion criteria.The noise exposure experiment was conducted using a verified phone app to record the sound levels. They were measured at 3 times, during a night shift, in the paediatric emergency department of UHW. All measurements were at a fixed distance and were averaged and compared with WHO recommendations.Results/ConclusionsThere are many sources of noise pollution in the ED, some are unavoidable for safety and clinical reasons.The literature review produced a small number of papers all of which found that sound levels were raised above recommended levels. Similarly, all the sounds measured in the ED also exceeded the recommendations.The most consistent finding across the papers, matched by findings from recordings, was that human behavioural modification is an easy and effective way to reduce noise levels.There are simple steps that can be taken to reduce and eliminate soundsRaising awareness regarding this problem is of great importance and focussing future work on assessing the impact in younger patients within the Emergency Department is paramount.

Incubator Noise

PEDIATRICS ◽  
1975 ◽  
Vol 56 (4) ◽  
pp. 617-617
Author(s):  
Gōsta Blennow ◽  
Nils W. Svenningsen ◽  
Bengt Almquist
Keyword(s):  
Low Frequency ◽  
Sound Level ◽  
Noise Levels ◽  
Frequency Sound ◽  
Mechanical Noise ◽  
Sound Levels ◽  
Infant Incubator ◽  
Improved Model ◽  
Model C

Recently we reported results from studies of incubator noise levels.1 It was found that in certain types of incubators the noise was considerable, and attention was called to the sound level in the construction of new incubators. Recently we had the opportunity to study an improved model of Isolette Infant Incubator Model C-86 where the mechanical noise from the electrically powered motor has been partially eliminated. With this modification it has been possible to lower the low-frequency sound levels to a certain degree in comparison to the levels registered in our study.

Station facilities and noise assessment: A multilevel analysis on light rail train stations

2021 ◽  
Vol 69 (4) ◽  
pp. 364-372
Author(s):  
Yalcin Yildirim ◽  
Diane Jones Allen
Keyword(s):  
Public Transportation ◽  
Transportation Systems ◽  
Urban Life ◽  
Light Rail ◽  
Noise Levels ◽  
Transit Systems ◽  
Message Boards ◽  
Sound Levels ◽  
Noise Assessment ◽  
Ticket Vending Machines

Noise is one of the most frequent consequences of traffic. Public transportation systems, such as the Dallas Area Rapid Transit (DART) authority provides various modes of transportation. Even though the availability of commuting service for the public is a boon to communities, mass transit systems are potential sources of excessive sound levels in daily urban life. This article examines the nexus between the transit station facilities of light rail train (LRT) stations and noise implications at both station and neighborhood scales by studying selected LRT stations. A multilevel linear analysis was conducted to understand the degree of train station amenities and neighborhood characteristics that affect sound levels. Using a type II sound pressure level (SPL)meter, sound measurements were obtained during the weekdays and weekends over several weeks. Upon examining the station amenities, and built environment and sociodemographic characteristics of the neighborhood, findings of this comprehensive research reveal significant implications for sound levels. Stations with ticket vending machines and informative message boards include a higher degree of significance on SPLs, while shelters, crew rooms, bike lockers, restrooms, and windshields are significantly and negatively associated with the noise levels. Additionally, neighborhoods with dense roads, higher speed limits, more neighborhood facilities, and a higher number of transit routes have an increased likelihood of noise levels. Recommendations include creating transformative policies for implementation, and approaches addressing noise for transit authorities, transportation engineers, and planners are presented. Planning and engineering aspects of comfort, aesthetics, safety, and public health, as train stations are daily use spaces for commuters and surrounding communities, should also be considered.

scholarly journals Appraisal of Noise Level Dissemination Surrounding Mining and Industrial Areas of Keonjhar, Odisha: a Comprehensive Approach Using Noise Mapping

2017 ◽  
Vol 42 (3) ◽  
pp. 423-432 ◽  
Author(s):  
Satish K. Lokhande ◽  
Satyajeet A. Dhawale ◽  
Samir S. Pathak ◽  
Rakesh Gautam ◽  
Mohindra C. Jain ◽  
...  
Keyword(s):  
Noise Level ◽  
Sound Level ◽  
Noise Levels ◽  
Night Time ◽  
Noise Mapping ◽  
High Noise ◽  
Sensitive Areas ◽  
Sound Levels ◽  
Directorate General ◽  
Open Cast

Abstract Noise mapping is a well-established practice among the European nations, and it has been follow for almost two decades. Recently, as per guidelines of the Directorate General of Mines Safety (DGMS), India, noise mapping has been made mandatory in the mining expanses. This study is an effort to map the noise levels in nearby areas of mines in the northern Keonjhar district. The motive of this study is to quantify the existing A-weighted time-average sound level (LAeq,T ) in the study area to probe its effects on the human dwellings and noise sensitive areas with the probability of future development of the mines, roads, and industrial and commercial zone. The LAeq,T was measured at 39 identified locations, including industrial, commercial, residential, and sensitive zones, 15 open cast mines, 3 major highways, and 3 haulage roads. With the utilisation of Predictor LimA Software and other GIS tools, the worked out data is mapped and noise contours are developed for the visualisation and identification of the extent and distribution of sound levels across the study area. This investigation discloses that the present noise level at 60% of the locations in silence and residential zone exposed to significantly high noise levels surpasses the prescribed limit of Central Pollution Control Board (CPCB), India. The observed day and night time LAeq, T level of both zones ranged between 43.2-62.2 dB(A) and 30.5-53.4 dB(A), respectively, whereas, the average Ldn values vary between 32.7 and 51.2 dB(A). The extensive mobility of heavy vehicles adjoining the sensitive areas and a nearby plethora of open cast mines is the leading cause of exceeded noise levels. The study divulges that the delicate establishments like schools and hospitals are susceptible to high noise levels throughout the day and night. A correlation between observed and software predicted values gives R2 of 0.605 for Ld, 0.217 for Ln, and 0.524 for Ldn. Finally, the mitigation measure is proposed and demonstrated using a contour map showing a significant reduction in the noise levels by 0-5.3 dB(A).

Noise Control Decision Process for Marine Vessels

2014 ◽  
Author(s):  
Raymond W. Fischer ◽  
Louis M. Pettit
Keyword(s):  
Marine Mammals ◽  
Noise Control ◽  
Regulatory Body ◽  
Noise Levels ◽  
Radiated Noise ◽  
Underwater Radiated Noise ◽  
Sound Levels ◽  
Airborne Noise ◽  
Control Decision ◽  
Marine Vessels

There is a price to be paid to achieve compliance with the acoustic requirements imposed by regulatory agencies. Acoustic requirements typically appear in ship specifications as airborne and/or underwater radiated noise limits as the need to preclude hearing loss for crew members and the need to control sound levels experienced by marine mammals receive more recognition. Recent changes and additions to regulatory body requirements addressing compartment airborne noise and underwater radiated noise can be found in IMO Resolution MSC.337(91) Annex 1 and Annex 2 which state that IMO Resolution A.468(XII) “Code on Noise Levels Onboard Ships” shall take effect on 1 July 2014 for all SOLAS compliant vessels. Thus the airborne noise levels in compartments and at on-deck work stations onboard as-built ships seeking a SOLAS certificate will need to be measured, and must demonstrate compliance with noise limits stated in paragraph 4.2 of IMO Resolution A.468(XII). IMO “Guidelines for the Reduction of Underwater Noise from Commercial Shipping to Address Adverse Impacts on Marine Life” dated 7 April 2014 and agencies such as ICES and DNV have established guidance and/or criteria for control of underwater radiated noise from vessels, and these too are now commonly appearing in ship specifications. Specifications referencing such criteria typically require that compliance be demonstrated by at-sea testing of underwater radiated noise. Making the correct decisions during the ship design process will minimize costs for noise control and will provide a positive return on investment. The process of how best to comply with noise limits while minimizing costs through optimization of noise control treatments and design approaches is discussed.

A New Quasi-Steady In-Ground Effect Model for Rotorcraft Unmanned Aerial Vehicles

2019 ◽  
Author(s):  
Xiang He ◽  
Kam K. Leang
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Ground Plane ◽  
Ground Effect ◽  
P Value ◽  
Model Parameters ◽  
Blade Element Theory ◽  
Aerial Vehicles ◽  
Effect Model ◽  
3D Printed ◽  
Induced Velocity

Abstract This paper introduces a new quasi-steady in-ground effect model for rotorcraft unmanned aerial vehicles to predict the aerodynamic behavior when the vehicle’s rotors approach ground plane. The model assumes that the compression of the outflow due to the presence of ground plane induces a change in the induced velocity that can drastically affect the thrust and power output. The new empirical model describes the change in thrust as a function of the distance to an obstacle for a rotor in hover condition. Using blade element theory and the method of image, the model parameters are described in terms of the rotor pitch angle and solidity. Experiments with off-the-shelf, fixed-pitch propellers and 3D-printed variable pitch propellers are carried out to validate the model. Experimental results suggest good agreement with 9.5% root-mean-square error (RMSE) and 97% p-value of statistic significance.

scholarly journals A Comparison of Sound Levels in Open Plan Versus Pods in a Neonatal Intensive Care Unit

2016 ◽  
Vol 10 (3) ◽  
pp. 30-39 ◽  
Author(s):  
Karlie Ramm ◽  
Trudi Mannix ◽  
Yvonne Parry ◽  
Mary P. (Caroline) Gaffney
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Neonatal Intensive Care Unit ◽  
Observational Data ◽  
Neonatal Intensive Care ◽  
Careful Consideration ◽  
Noise Levels ◽  
Sound Levels ◽  
Open Plan ◽  
Average Noise Level

Objective: The objective of this study was to compare the noise levels recorded in two different neonatal intensive care unit (NICU) settings: a pod and an open plan NICU located in the same hospital. Background: The NICU is a busy environment with ambient noise levels that often exceed established recommendations. This noise deleteriously affects the physiological stability and developmental outcomes of sick and preterm infants. Pods have reduced numbers of cots (in this case, 6) compared to open plan NICUs (in this case, 11), yet the noise levels in pods have not been reported. Method: This study compared real-time decibel (dB) levels in an A-weighted scale, captured continuously by sound dosimeters mounted in both NICU settings for a period of 4 weeks: a pod setting and an open plan NICU. Researchers also collected observational data. Results: The average noise level recorded in the pod was 3 dBs less than in the open plan NICU. This result was statistically significant. However, dB recordings in both areas were over the recommended limits by 4–6 dBs, with isolated peaks between 74.5 dBs (NICU) and 75.9 dBs (pod). Observational data confirmed this correlation. Conclusions: Further research to evaluate interventions to decrease the noise levels in both settings are needed, especially during times of peak activity. Staff working in these settings need to be more aware that control of acoustic levels is important in the neuroprotection of neonates. Coupling this with careful consideration to structural components and evidence-based design planning may contribute to lowering dB levels in the NICU environment.

Suction tube noise and myringotomy

1980 ◽  
Vol 94 (4) ◽  
pp. 383-386 ◽  
Author(s):  
M. G. Spencer
Keyword(s):  
Hearing Loss ◽  
Otitis Media ◽  
External Auditory Meatus ◽  
Noise Induced Hearing Loss ◽  
Noise Levels ◽  
Suction Tube ◽  
Sound Levels ◽  
High Level

AbstactThe possibility of a noise-induced hearing loss occurring as a result of a high level of sucker-tip noise in myringtomy for seromucinous otitis media is discussed, A group of twenty-four ears is investigated and the noise levels generated by the suction tube are mearsured at operation by means of a probe microphone lowered into the external auditory meatus The conclusions reached are that, although the sound levels attained are at times quite high, they are not of suffcient amplitude, nor are they present for a suffcient length of time, to produce a sencori-neural hearing loss.

Underwater noise and Arctic marine mammals: review and policy recommendations

2020 ◽  
Vol 28 (4) ◽  
pp. 438-448 ◽  
Author(s):  
William D. Halliday ◽  
Matthew K. Pine ◽  
Stephen J. Insley
Keyword(s):  
Sea Ice ◽  
Marine Mammals ◽  
Anthropogenic Activities ◽  
The Arctic ◽  
Auditory Masking ◽  
Underwater Noise ◽  
Noise Levels ◽  
Marine Animals ◽  
Sound Levels ◽  
Ambient Sound

Underwater noise is an important issue globally. Underwater noise can cause auditory masking, behavioural disturbance, hearing damage, and even death for marine animals. While underwater noise levels have been increasing in nonpolar regions, noise levels are thought to be much lower in the Arctic where the presence of sea ice limits anthropogenic activities. However, climate change is causing sea ice to decrease, which is allowing for increased access for noisy anthropogenic activities. Underwater noise may have more severe impacts in the Arctic compared with nonpolar regions due to a combination of lower ambient sound levels and increased sensitivity of Arctic marine animals to underwater noise. Here, we review ambient sound levels in the Arctic, as well as the reactions of Arctic and sub-Arctic marine mammals to underwater noise. We then relate what is known about underwater noise in the Arctic to policies and management solutions for underwater noise and discuss whether Arctic-specific policies are necessary.

Research on the influence of ground effect on the performance of robotic fish propelled by oscillating paired pectoral fins

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hongwei Ma ◽  
Shuai Ren ◽  
Junxiang Wang ◽  
Hui Ren ◽  
Yang Liu ◽  
...  
Keyword(s):  
Ground Effect ◽  
Robotic Fish ◽  
Two Dimensional ◽  
Pectoral Fin ◽  
Content Type ◽  
Pectoral Fins ◽  
Propulsion Performance ◽  
Effect Model ◽  
Hydrodynamic Experiments ◽  
Flexible Deformation

Purpose This paper aims to carry out the research on the influence of ground effect on the performance of robotic fish propelled by oscillating paired pectoral fins. Design/methodology/approach The two-dimensional ground effect model of the oscillating pectoral fin without considering flexible deformation is established by introducing a two-dimensional fluid ground effect model. The parameters of the influence of ground effect on the oscillating pectoral fin are analyzed. Finally, the ground effect test platform is built, and a series of hydrodynamic experiments are carried out to study the influence of ground effect on the propulsion performance of the robotic fish propelled by oscillating paired pectoral fins under different motion parameters. Findings The thickness of the trailing edge and effective clearance are two important parameters that can change the influence of ground effect on the rigid pectoral fin. The experimental results are consistent with that obtained through theoretical analysis within a certain extent, which indicates that the developed two-dimensional ground effect model in this paper can be used to analyze the influence of ground effect on the propulsion performance of the oscillating pectoral fin. The experiment results show that the average thrust increases with the decreasing distance between the robot fish and the bottom. Meanwhile, with the increase of oscillation frequency and amplitude, the average thrust increases gradually. Originality/value The developed two-dimensional ground effect model provides the theoretical basis for the further research on the influence of ground effect on the propulsion performance of the oscillating pectoral fin. It can also be used in the design of the bionic pectoral fins.

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