WorldWideScience

Sample records for aircraft noise

  1. Aircraft Noise

    Science.gov (United States)

    Michel, Ulf; Dobrzynski, Werner; Splettstoesser, Wolf; Delfs, Jan; Isermann, Ullrich; Obermeier, Frank

    Aircraft industry is exposed to increasing public pressure aiming at a continuing reduction of aircraft noise levels. This is necessary to both compensate for the detrimental effect on noise of the expected increase in air traffic and improve the quality of living in residential areas around airports.

  2. Aircraft noise prediction

    Science.gov (United States)

    Filippone, Antonio

    2014-07-01

    This contribution addresses the state-of-the-art in the field of aircraft noise prediction, simulation and minimisation. The point of view taken in this context is that of comprehensive models that couple the various aircraft systems with the acoustic sources, the propagation and the flight trajectories. After an exhaustive review of the present predictive technologies in the relevant fields (airframe, propulsion, propagation, aircraft operations, trajectory optimisation), the paper addresses items for further research and development. Examples are shown for several airplanes, including the Airbus A319-100 (CFM engines), the Bombardier Dash8-Q400 (PW150 engines, Dowty R408 propellers) and the Boeing B737-800 (CFM engines). Predictions are done with the flight mechanics code FLIGHT. The transfer function between flight mechanics and the noise prediction is discussed in some details, along with the numerical procedures for validation and verification. Some code-to-code comparisons are shown. It is contended that the field of aircraft noise prediction has not yet reached a sufficient level of maturity. In particular, some parametric effects cannot be investigated, issues of accuracy are not currently addressed, and validation standards are still lacking.

  3. Challenges in Aircraft Noise Prediction

    OpenAIRE

    Filippone A

    2014-01-01

    This contribution addresses the problem of aircraft noise prediction using theoretical methods. The problem is set in context with the needs at several levels to produce noise characterisation from commercial aircraft powered by gas turbine engines. We describe very briefly the computational model (whilst referring the reader to the appropriate literature), and provide examples of noise predictions and comparisons with measured data, where possible. We focus on the issue of stochastic analysi...

  4. Aircraft noise and birth weight

    Energy Technology Data Exchange (ETDEWEB)

    Knipschild, P.; Meijer, H.; Salle, H.

    1981-05-01

    Data from six infant welfare centres in the vicinity of Amsterdam airport were analysed. Birth weights of 902 infants were related to aircraft noise levels to which the mother was exposed in pregnancy. The analysis was restricted to deliveries in hospital, single births and mothers aged 20-34 years. In high noise areas the mean birth weight was 69 g lower than in low noise areas. Of the infants in high noise areas 24% had a birth weight less than 3000 g, compared with 18% in low noise areas. In the analysis the effect of sex of the infant, birth order and to some extent socio-economic status were taken into account. An effect of smoking seemed unlikely. The results, together with existing knowledge, give some suggestion that aircraft noise can decrease birth weight.

  5. PREDICTION OF AIRCRAFT NOISE LEVELS

    Science.gov (United States)

    Clark, B. J.

    1994-01-01

    Methods developed at the NASA Lewis Research Center for predicting the noise contributions from various aircraft noise sources have been incorporated into a computer program for predicting aircraft noise levels either in flight or in ground test. The noise sources accounted for include fan inlet and exhaust, jet, flap (for powered lift), core (combustor), turbine, and airframe. Noise propagation corrections are available in the program for atmospheric attenuation, ground reflections, extra ground attenuation, and shielding. The capacity to solve the geometrical relationships between an aircraft in flight and an observer on the ground has been included in the program to make it useful in evaluating noise estimates and footprints for various proposed engine installations. The program contains two main routines for employing the noise prediction routines. The first main routine consists of a procedure to calculate at various observer stations the time history of the noise from an aircraft flying at a specified set of speeds, orientations, and space coordinates. The various components of the noise are computed by the program. For each individual source, the noise levels are free field with no corrections for propagation losses other than spherical divergence. The total spectra may then be corrected for the usual effects of atmospheric attenuation, extra ground attenuation, ground reflection, and aircraft shielding. Next, the corresponding values of overall sound pressure level, perceived noise level, and tone-weighted perceived noise level are calculated. From the time history at each point, true effective perceived noise levels are calculated. Thus, values of effective perceived noise levels, maximum perceived noise levels, and tone-weighted perceived noise levels are found for a grid of specified points on the ground. The second main routine is designed to give the usual format of one-third octave sound pressure level values at a fixed radius for a number of user

  6. Aircrafts' taxi noise emission

    OpenAIRE

    Asensio Rivera, César; Pagán Muñoz, Raúl; López Navarro, Juan Manuel

    2008-01-01

    During planning stages, when noisy activity has not been implanted or while evaluating operation changes, it is necessary to find an environmental noise mapping prediction tool for future scenarios. When an activity is already implanted, it is possible to measure noise emissions, but this is expensive, so prediction tools can also be useful. Because of these reasons, for the last 10 years, as a response to the increasing concern for noise pollution in developed countries, several simulation m...

  7. Policy and the evaluation of aircraft noise

    NARCIS (Netherlands)

    Kroesen, M.; Molin, E.J.E.; Van Wee, G.P.

    2010-01-01

    In this paper, we hypothesize and test the ideas that (1) people’s subjectivity in relation to aircraft noise is shaped by the policy discourse, (2) this results in a limited number of frames towards aircraft noise, (3) the frames inform people how to think and feel about aircraft noise and (4) the

  8. Noise control mechanisms of inside aircraft

    Science.gov (United States)

    Zverev, A. Ya.

    2016-07-01

    World trends in the development of methods and approaches to noise reduction in aircraft cabins are reviewed. The paper discusses the mechanisms of passive and active noise and vibration control, application of "smart" and innovative materials, new approaches to creating all fuselage-design elements, and other promising directions of noise control inside aircraft.

  9. Research on Emerging and Descending Aircraft Noise

    OpenAIRE

    Monika Bartkevičiūtė; Raimondas Grubliauskas

    2013-01-01

    Along with an increase in the aircraft engine power and growth in air traffic, noise level at airports and their surrounding environs significantly increases. Aircraft noise is high level noise spreading within large radius and intensively irritating the human body. Air transport is one of the main sources of noise having a particularly strong negative impact on the environment. The article deals with activities and noises taking place in the largest nationwide Vilnius International Airport.T...

  10. Aircraft noise - Different ways to monitor the noise load

    Science.gov (United States)

    Bekebrede, G.

    Measures taken by the Dutch government to reduce aircraft-noise disturbances including the establishment of noise zones in which subsequent building is forbidden, while already existing homes are provided with noise insulation are discussed. To ensure accurate noise monitoring, the following recommendations were made by the NLR: (1) regular noise load calculations, utilizing aircraft noise and performance data, the air traffic mix, and flight route information; (2) flight track monitoring, performed by a computerized Flight Track and Aircraft Noise Monitoring System which identifies all aircraft deviating from the prescribed track (i.e., flying over congested regions); and (3) actual noise monitoring, to guard the noise level at a specific noise-sensitive area in close proximity to the airfield, such as a hospital.

  11. Residents' Annoyance Responses to Aircraft Noise Events

    OpenAIRE

    United States, National Aeronautics and Space Administration

    1983-01-01

    In a study conducted in the vicinity of Salt Lake City International Airport, community residents reported their annoyance with individual aircraft flyovers during rating sessions conducted in their homes. Annoyance ratings were obtained at different times of the day. Aircraft noise levels were measured, and other characteristics of the aircraft were noted by trained observers. Metrics commonly used for assessing aircraft noise were compared, but none performed significantly better than A-...

  12. Noise Control and Noise Evaluation in Aircraft Engines

    OpenAIRE

    石井, 達哉; Ishii, Tatsuya

    2002-01-01

    Aircraft engine noise emitted for example by the jet exhaust, fan, compressor, turbine and combustor is the predominant factor in total aircraft noise during take-off and landing. As a result of enormous efforts to alleviate engine noise, noise levels have been improved by more than 20 dB compared to the first generation of airliners. However, the growing volume of air transport means that further noise reduction is still required. With this background, we decided to concentrate on two techni...

  13. Policy and the evaluation of aircraft noise

    OpenAIRE

    Kroesen, M.; Molin, E.J.E.; Van Wee, G.P.

    2010-01-01

    In this paper, we hypothesize and test the ideas that (1) people’s subjectivity in relation to aircraft noise is shaped by the policy discourse, (2) this results in a limited number of frames towards aircraft noise, (3) the frames inform people how to think and feel about aircraft noise and (4) the distribution of the frames in the population is dependent on structural variables related to the individual. To reveal subjects’ frames of aircraft noise a latent class model is estimated based on ...

  14. Research on Emerging and Descending Aircraft Noise

    Directory of Open Access Journals (Sweden)

    Monika Bartkevičiūtė

    2013-12-01

    Full Text Available Along with an increase in the aircraft engine power and growth in air traffic, noise level at airports and their surrounding environs significantly increases. Aircraft noise is high level noise spreading within large radius and intensively irritating the human body. Air transport is one of the main sources of noise having a particularly strong negative impact on the environment. The article deals with activities and noises taking place in the largest nationwide Vilnius International Airport.The level of noise and its dispersion was evaluated conducting research on the noise generated by emerging and descending aircrafts in National Vilnius Airport. Investigation was carried out at 2 measuring points located in a residential area. There are different types of aircrafts causing different sound levels. It has been estimated the largest exceedances that occur when an aircraft is approaching. In this case, the noisiest types of aircrafts are B733, B738 and AT72. The sound level varies from 70 to 85 dBA. The quietest aircrafts are RJ1H and F70. When taking off, the equivalent of the maximum sound level value of these aircrafts does not exceed the authorized limits. The paper describes the causes of noise in aircrafts, the sources of origin and the impact of noise on humans and the environment.Article in Lithuanian

  15. Beamforming for aircraft noise measurements

    Science.gov (United States)

    Dougherty, Robert P.

    2003-10-01

    Phased array beamforming for aircraft noise source location has a long history, including early work on jet noise, wind tunnel measurements, and flyover testing. In the last 10 years, advancements in sparse 2-D and 3-D arrays, wind tunnel test techniques, and computer power have made phased array measurements almost common. Large aerospace companies and national research institutes have an advantage in access to major facilities and hundreds of measurement microphones, but universities and even consulting companies can perform tests with electret microphones and PC data acquisition systems. The type of testing remains a blend of science and art. A complex noise source is approximated by a mathematical model, and the microphones are deployed to evaluate the parameters of the model. For example, the simplest, but often the best, approach is to assume a distribution of mutually incoherent monopoles. This leads to an imaging process analogous to photography. Other models include coherent distributions of multipoles or duct modes. It is sometimes important to simulate the results that would have been obtained from single microphone measurements of part of the airplane in an ideal environment, had such measurements been feasible.

  16. Control strategies for aircraft airframe noise reduction

    Institute of Scientific and Technical Information of China (English)

    Li Yong; Wang Xunnian; Zhang Dejiu

    2013-01-01

    With the development of low-noise aircraft engine,airframe noise now represents a major noise source during the commercial aircraft's approach to landing phase.Noise control efforts have therefore been extensively focused on the airframe noise problems in order to further reduce aircraft overall noise.In this review,various control methods explored in the last decades for noise reduction on airframe components including high-lift devices and landing gears are summarized.We introduce recent major achievements in airframe noise reduction with passive control methods such as fairings,deceleration plates,splitter plates,acoustic liners,slat cove cover and side-edge replacements,and then discuss the potential and control mechanism of some promising active flow control strategies for airframe noise reduction,such as plasma technique and air blowing/suction devices.Based on the knowledge gained throughout the extensively noise control testing,a few design concepts on the landing gear,high-lift devices and whole aircraft are provided for advanced aircraft low-noise design.Finally,discussions and suggestions are given for future research on airframe noise reduction.

  17. Active Noise Control in Propeller Aircraft

    OpenAIRE

    Johansson, Sven; Claesson, Ingvar

    2001-01-01

    A noisy environment dominated by low frequency noise can often be improved through the use of active noise control. This situation arises naturally in propeller aircraft where the propellers induce periodic low frequency noise inside the cabin. The cabin noise is typically rather high, and the passenger flight comfort could be improved considerably if this level were significantly reduced. This paper addresses same design aspects for multiple-reference active noise control systems based on th...

  18. Directional monitoring terminal for aircraft noise

    Science.gov (United States)

    Genescà, M.

    2016-07-01

    This paper presents a concept of an aircraft noise monitoring terminal (NMT) that reduces background noise and the influence of ground reflection, in comparison with a single microphone. Also, it automatically identifies aircraft sound events based on the direction of arrival of the sound rather than on the sound pressure level (or radar data). And moreover, it provides an indicator of the quality of the sound pressure level measurement, i.e. if it is possibly disturbed by extraneous sources. The performance of this NMT is experimentally tested under real conditions in a measurement site close to Zurich airport. The results show that the NMT unambiguously identifies the noise events generated by the target aircraft, correctly detects those aircraft noise events that may be disturbed by the presence of other sources, and offers a substantial reduction in background and ground reflected sound.

  19. Aircraft Noise: Annoyance, House Prices and Valuation

    OpenAIRE

    Brooker, Peter

    2006-01-01

    “Nobody wants to buy your house. It’s the aircraft noise. You’ll have to reduce the price a lot.” Aircraft noise around airports causes annoyance, and tends to reduce the price of affected properties. Can annoyance be ‘costed’ by examining house price reductions? Are there other ways of valuing annoyance in monetary terms? This short paper summarises key research results and poses some questions.

  20. ANASE: measuring aircraft noise annoyance very unreliably.

    OpenAIRE

    Brooker, Peter

    2008-01-01

    Does anyone who lives under a flight-path like aircraft noise? It is a political hot potato as well as a peace-destroyer. Tens of thousands of people will hear the noise from any third runway at Heathrow. So, when a study commissioned by the government claimed that people are becoming less tolerant of aircraft noise, it made highly unpleasant reading for supporters of a third runway. But the Department for Transport rejected the report as unreliable. Peter Brooker senses the vibrations.

  1. Trajectory management for aircraft noise mitigation

    OpenAIRE

    Prats Menéndez, Xavier; Quevedo Casín, Joseba Jokin; Puig Cayuela, Vicenç

    2009-01-01

    Comunicació convidada This paper gives an overview of aircraft trajectory management aimed at producing noise abatementprocedures. Area Navigation (RNAV) concepts play an important role in the design of flexible and, therefore, noise friendly depart or approach procedures. In addition, the lowest dispersion of RNAV tracks help to contain noise footprints in a smaller area if compared with footprints that are produced when conventional procedures are flown. However, RNAV turns still produce...

  2. A measurement method to discriminate aircraft fly-over noise

    OpenAIRE

    Genesca Francitorra, Meritxell; Romeu Garbí, Jordi; Pàmies Gómez, Teresa

    2010-01-01

    Currently aircraft noise monitoring systems use a mesh of single microphones distributed around an airport to continuously sample the noise level. This fact requires a manual process of aircraft noise event detection and classification in order to distinguish aircraft events from the rest of noise events in the recording. In the present paper a 3-meter-long 12-microphone linear array is used to automatically obtain a background noise free aircraft noise recording. The beamforming process sepa...

  3. Aircraft Noise and Quality of Life around Frankfurt Airport

    OpenAIRE

    Thomas Eikmann; Christin Peschel; Cara Kahl; Dirk Schreckenberg; Markus Meis

    2010-01-01

    In a survey of 2,312 residents living near Frankfurt Airport aircraft noise annoyance and disturbances as well as environmental (EQoL) and health-related quality of life (HQoL) were assessed and compared with data on exposure due to aircraft, road traffic, and railway noise. Results indicate higher noise annoyance than predicted from general exposure-response curves. Beside aircraft sound levels source-related attitudes were associated with reactions to aircraft noise. Furthermore, aircraft n...

  4. Review of Aircraft Engine Fan Noise Reduction

    Science.gov (United States)

    VanZante, Dale

    2008-01-01

    Aircraft turbofan engines incorporate multiple technologies to enhance performance and durability while reducing noise emissions. Both careful aerodynamic design of the fan and proper installation of the fan into the system are requirements for achieving the performance and acoustic objectives. The design and installation characteristics of high performance aircraft engine fans will be discussed along with some lessons learned that may be applicable to spaceflight fan applications.

  5. Recent Progress in Aircraft Noise Research

    Science.gov (United States)

    Envia, Edmane; Thomas, Russell

    2007-01-01

    An overview of the acoustics research at NASA under the Subsonic Fixed Wing project is given. The presentation describes the rationale behind the noise reduction goals of the project in the context of the next generation air transportation system, and the emphasis placed on achieving these goals through a combination of the in-house and collaborative efforts with industry, universities and other government agencies. The presentation also describes the in-house research plan which is focused on the development of advanced noise and flow diagnostic techniques, next generation noise prediction tools, and novel noise reduction techniques that are applicable across a wide range of aircraft.

  6. Assessment of NASA's Aircraft Noise Prediction Capability

    Science.gov (United States)

    Dahl, Milo D. (Editor)

    2012-01-01

    A goal of NASA s Fundamental Aeronautics Program is the improvement of aircraft noise prediction. This document provides an assessment, conducted from 2006 to 2009, on the current state of the art for aircraft noise prediction by carefully analyzing the results from prediction tools and from the experimental databases to determine errors and uncertainties and compare results to validate the predictions. The error analysis is included for both the predictions and the experimental data and helps identify where improvements are required. This study is restricted to prediction methods and databases developed or sponsored by NASA, although in many cases they represent the current state of the art for industry. The present document begins with an introduction giving a general background for and a discussion on the process of this assessment followed by eight chapters covering topics at both the system and the component levels. The topic areas, each with multiple contributors, are aircraft system noise, engine system noise, airframe noise, fan noise, liner physics, duct acoustics, jet noise, and propulsion airframe aeroacoustics.

  7. Human Response to Aircraft Noise

    NARCIS (Netherlands)

    Kroesen, M.

    2011-01-01

    How can it be that one person is extremely annoyed by the sounds of aircrafts, while his neighbour claims not to be bothered at all? The present thesis attempts to explain this observation by applying a range of quantitative methods to field data gathered among residents living near large airports.

  8. Aircraft Noise and Quality of Life around Frankfurt Airport

    Directory of Open Access Journals (Sweden)

    Thomas Eikmann

    2010-08-01

    Full Text Available In a survey of 2,312 residents living near Frankfurt Airport aircraft noise annoyance and disturbances as well as environmental (EQoL and health-related quality of life (HQoL were assessed and compared with data on exposure due to aircraft, road traffic, and railway noise. Results indicate higher noise annoyance than predicted from general exposure-response curves. Beside aircraft sound levels source-related attitudes were associated with reactions to aircraft noise. Furthermore, aircraft noise affected EQoL in general, although to a much smaller extent. HQoL was associated with aircraft noise annoyance, noise sensitivity and partly with aircraft noise exposure, in particular in the subgroup of multimorbid residents. The results suggest a recursive relationship between noise and health, yet this cannot be tested in cross-sectional studies. Longitudinal studies would be recommendable to get more insight in the causal paths underlying the noise-health relationship.

  9. Empirical Prediction of Aircraft Landing Gear Noise

    Science.gov (United States)

    Golub, Robert A. (Technical Monitor); Guo, Yue-Ping

    2005-01-01

    This report documents a semi-empirical/semi-analytical method for landing gear noise prediction. The method is based on scaling laws of the theory of aerodynamic noise generation and correlation of these scaling laws with current available test data. The former gives the method a sound theoretical foundation and the latter quantitatively determines the relations between the parameters of the landing gear assembly and the far field noise, enabling practical predictions of aircraft landing gear noise, both for parametric trends and for absolute noise levels. The prediction model is validated by wind tunnel test data for an isolated Boeing 737 landing gear and by flight data for the Boeing 777 airplane. In both cases, the predictions agree well with data, both in parametric trends and in absolute noise levels.

  10. Aircraft noise and its nearfield propagation computations

    Science.gov (United States)

    Zhang, Xin

    2012-08-01

    Noise generated by civil transport aircraft during take-off and approach-to-land phases of operation is an environmental problem. The aircraft noise problem is firstly reviewed in this article. The review is followed by a description and assessment of a number of sound propagation methods suitable for applications with a background mean flow field pertinent to aircraft noise. Of the three main areas of the noise problem, i.e. generation, propagation, and radiation, propagation provides a vital link between near-field noise generation and far-field radiation. Its accurate assessment ensures the overall validity of a prediction model. Of the various classes of propagation equations, linearised Euler equations are often casted in either time domain or frequency domain. The equations are often solved numerically by computational aeroacoustics techniques, bur are subject to the onset of Kelvin-Helmholtz (K-H) instability modes which may ruin the solutions. Other forms of linearised equations, e.g. acoustic perturbation equations have been proposed, with differing degrees of success.

  11. Aircraft noise and its nearfield propagation computations

    Institute of Scientific and Technical Information of China (English)

    Xin Zhang

    2012-01-01

    Noise generated by civil transport aircraft during take-off and approach-to-land phases of operation is an environmental problem.The aircraft noise problem is firstly reviewed in this article.The review is followed by a description and assessment of a number of sound propagation methods suitable for applications with a background mean flow field pertinent to aircraft noise.Of the three main areas of the noise problem,i.e.generation,propagation,and radiation,propagation provides a vital link between near-field noise generation and far-field radiation.Its accurate assessment ensures the overall validity of a prediction model.Of the various classes of propagation equations,linearised Euler equations are often casted in either time domain or frequency domain.The equations are often solved numerically by computational aeroacoustics techniques,bur are subject to the onset of Kelvin-Helmholtz (K-H) instability modes which may ruin the solutions. Other forms of linearised equations,e.g.acoustic perturbation equations have been proposed,with differing degrees of success.

  12. Monetary Valuation of Aircraft Noise

    OpenAIRE

    Dekkers, Jasper; van der Straaten, Willemijn

    2008-01-01

    In densely-populated countries and in particular in large metropolitan areas, the presence of so much human activity causes all sorts of negative externalities, for example traffic noise disturbance. These externalities call for corrective measures by the government. Economists have developed a number of procedures that provide reasonable estimates on the monetary value of some amenities and externalities. In this paper we develop a spatially-explicit hedonic pricing model for house prices in...

  13. 75 FR 9327 - Aircraft Noise Certification Documents for International Operations

    Science.gov (United States)

    2010-03-02

    ... Administration 14 CFR Part 91 RIN 2120-AJ31 Aircraft Noise Certification Documents for International Operations... operating rules to require U.S. operators flying outside the United States to carry aircraft noise..., Subpart III, Section 44715, Controlling aircraft noise and sonic boom. Under that section, the FAA...

  14. Overview of Aircraft Noise Prediction Tools Assessment

    Science.gov (United States)

    Dahl, Milo D.

    2007-01-01

    The acoustic assessment task for both the Subsonic Fixed Wing and the Supersonic projects under NASA s Fundamental Aeronautics Program was designed to assess the current state-of-the-art in noise prediction capability and to establish baselines for gauging future progress. The documentation of our current capabilities included quantifying the differences between predictions of noise from computer codes and measurements of noise from experimental tests. Quantifying the accuracy of both the computed and experimental results further enhanced the credibility of the assessment. This presentation gives sample results from codes representative of NASA s capabilities in aircraft noise prediction at the system level and at the component level. These include semi-empirical, statistical, analytical, and numerical codes. An example of system level results is shown for an aircraft. Component level results are shown for airframe flaps and landing gear, for jet noise from a variety of nozzles, and for broadband fan noise. Additional results are shown for modeling of the acoustic behavior of duct acoustic lining and the attenuation of sound in lined ducts with flow.

  15. Assessment of aircraft noise sources variability using an acoustic camera

    NARCIS (Netherlands)

    Snellen, M.; Merino Martinez, R.; Simons, D.G.

    2015-01-01

    Noise assessment around airports is hampered due to the observed large variability in noise levels for fly-overs of the same aircraft type, which is not considered by the current models. This paper assumes that the noise variability is due to variations in the aircraft emitted noise, neglecting the

  16. Modeling aircraft noise induced sleep disturbance

    Science.gov (United States)

    McGuire, Sarah M.

    One of the primary impacts of aircraft noise on a community is its disruption of sleep. Aircraft noise increases the time to fall asleep, the number of awakenings, and decreases the amount of rapid eye movement and slow wave sleep. Understanding these changes in sleep may be important as they could increase the risk for developing next-day effects such as sleepiness and reduced performance and long-term health effects such as cardiovascular disease. There are models that have been developed to predict the effect of aircraft noise on sleep. However, most of these models only predict the percentage of the population that is awakened. Markov and nonlinear dynamic models have been developed to predict an individual's sleep structure during the night. However, both of these models have limitations. The Markov model only accounts for whether an aircraft event occurred not the noise level or other sound characteristics of the event that may affect the degree of disturbance. The nonlinear dynamic models were developed to describe normal sleep regulation and do not have a noise effects component. In addition, the nonlinear dynamic models have slow dynamics which make it difficult to predict short duration awakenings which occur both spontaneously and as a result of nighttime noise exposure. The purpose of this research was to examine these sleep structure models to determine how they could be altered to predict the effect of aircraft noise on sleep. Different approaches for adding a noise level dependence to the Markov Model was explored and the modified model was validated by comparing predictions to behavioral awakening data. In order to determine how to add faster dynamics to the nonlinear dynamic sleep models it was necessary to have a more detailed sleep stage classification than was available from visual scoring of sleep data. An automatic sleep stage classification algorithm was developed which extracts different features of polysomnography data including the

  17. Visualizing interior and exterior jet aircraft noise

    Science.gov (United States)

    Moondra, Manmohan S.

    In today's competitive aerospace industry, the quest for quiet has drawn significant attention to both the interior and exterior design of an airplane. Understanding the noise generation mechanisms of a jet aircraft is a crucial first step toward developing the most cost-effective noise and vibrations abatement methods. In this investigation, the Helmholtz Equation Least Squares (HELS) based nearfield acoustic holography will be used to understand noise transmission caused by jet engine and turbulence into the fuselage of a jet aircraft cruising at 30,000 ft. Modern propulsive jet engines produce exterior noise sources with a high amplitude noise field and complicated characteristics, which makes them very difficult to characterize. In particular, there are turbulent eddies that are moving through the jet at high speeds along the jet boundary. These turbulent eddies in the shear layer produce a directional and frequency dependent noise. The original HELS approach assumes a spherical source at the origin and computes the acoustic field based on spherical emission from this source. This assumption of one source at the origin is not sufficient to characterize a complex source like a jet. As such, a modified HELS approach is introduced that will help improve the source characterization as it is not dependent on a single source at the origin but a number of virtual sources throughout the space. Custom microphones are created to take acoustic pressure measurements around the jet engine. These measured acoustic pressures are then taken as input to the modified HELS algorithm to visualize the noise pattern of a subsonic jet engine.

  18. Sleep disturbance due to aircraft noise exposure

    Directory of Open Access Journals (Sweden)

    Lawrence S Finegold

    2010-01-01

    Full Text Available Research on nighttime sleep disturbance due to community noise sources, particularly from exposure to aircraft noise, has been conducted for over a half decade. However, there are still no national environmental noise policies (i.e., laws and regulations promulgated which prescribe a specific criterion for an exposure limit which is regulatory in nature. In the U.S., the new American National Standards Institute (ANSI Noise Standard, ANSI S12.9-2008/Part 6, Quantities and Procedures for Description and Measurement of Environmental Sound - Part 6: Methods for Estimation of Awakenings Associated with Outdoor Noise Events Heard in Homes, does provide the currently recommended exposure-response relationship used in the U.S. In Europe, there has also been significant laboratory and field research on sleep disturbance, although the U.S. and European research publications often use different research methodologies, different noise metrics and different meta-analysis techniques. The current article will provide a brief overview of sleep disturbance research internationally to document the similarities and differences between the various research approaches and research results.

  19. Aircraft noise exposure from Schiphol airport: A relation with complainants

    NARCIS (Netherlands)

    Jong, R.G. de; Wiechen, C.M.A.G. van; Franssen, E.A.M.; Lebret, E.

    2002-01-01

    The possible relation between aircraft noise exposure and the prevalence of complainants around Schiphol airport was studied. The home address of people who complain about aircraft noise at the Environment Advisory Committee Schiphol was combined with annual average noise levels, using a Geographic

  20. Advanced Acoustic Blankets for Improved Aircraft Interior Noise Reduction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this project advanced acoustic blankets for improved low frequency interior noise control in aircraft will be developed and demonstrated. The improved...

  1. Signal processing of aircraft flyover noise

    Science.gov (United States)

    Kelly, J. J.

    1993-01-01

    A detailed analysis of signal processing concerns for measuring aircraft flyover noise is presented. Development of a de-Dopplerization scheme for both corrected time history and spectral data is discussed along with an analysis of motion effects on measured spectra. A computer code was written to implement the de-Dopplerization scheme. Input to the code is the aircraft position data and the pressure time histories. To facilitate ensemble averaging, a level uniform flyover is considered in the study, but the code can accept more general flight profiles. The effects of spectral smearing and its removal are discussed. Using test data acquired from an XV-15 tilt-rotor flyover, comparisons are made between the measured and corrected spectra. Frequency shifts are accurately accounted for by the de-Dopplerization procedure. It is shown that by correcting for spherical spreading and Doppler amplitude, along with frequency, can give some idea about noise source directivity. The analysis indicated that smearing increases with frequency and is more severe on approach than recession.

  2. Plasma Fairings for Quieting Aircraft Landing Gear Noise Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A major component of airframe noise for commercial transport aircraft is the deployed landing gear. The noise from the gear originates due to complex, unsteady...

  3. Assessment of aircraft noise sources variability using an acoustic camera

    OpenAIRE

    Snellen, M.; Merino Martinez, R.; Simons, D.G.

    2015-01-01

    Noise assessment around airports is hampered due to the observed large variability in noise levels for fly-overs of the same aircraft type, which is not considered by the current models. This paper assumes that the noise variability is due to variations in the aircraft emitted noise, neglecting the effect of the variable atmosphere, as previous work showed that its contribution is maximally 2 dB. In order to quantify and investigate the variability of noise levels during aircraft fly-overs, 1...

  4. Aircraft noise and speech intelligibility in an outdoor living space.

    Science.gov (United States)

    Alvarsson, Jesper J; Nordström, Henrik; Lundén, Peter; Nilsson, Mats E

    2014-06-01

    Studies of effects on speech intelligibility from aircraft noise in outdoor places are currently lacking. To explore these effects, first-order ambisonic recordings of aircraft noise were reproduced outdoors in a pergola. The average background level was 47 dB LA eq. Lists of phonetically balanced words (LAS max,word = 54 dB) were reproduced simultaneously with aircraft passage noise (LAS max,noise = 72-84 dB). Twenty individually tested listeners wrote down each presented word while seated in the pergola. The main results were (i) aircraft noise negatively affects speech intelligibility at sound pressure levels that exceed those of the speech sound (signal-to-noise ratio, S/N aircraft noise on speech intelligibility outdoors. PMID:24907809

  5. The community response to aircraft noise around six Spanish airports

    Science.gov (United States)

    Garcia, A.; Faus, L. J.; Garcia, A. M.

    1993-06-01

    The community response to aircraft noise has been studied through a social survey. A total of 1800 persons living in the vicinity of six major Spanish airports have been interviewed at their homes concerning the environmental quality of the area, dissatisfaction with road traffic noise and aircraft noise, activities interfered with by noise, most disturbing aircraft types, and subjective evaluation of airport impact. All the responses obtained in this survey have been compared with aircraft noise levels corresponding to the residence locations of the people interviewed (values of NEF levels were calculated with the INM model). The results obtained in this work allow one to evaluate the impact of aircraft noise under a wide range of different situations.

  6. Optimization of operational aircraft parameters reducing noise emission

    OpenAIRE

    Abdallah, Lina; Khardi, Salah; Haddou, Mounir

    2010-01-01

    The objective of this paper is to develop a model and a minimization method to provide flight path optimums reducing aircraft noise in the vicinity of airports. Optimization algorithm has solved a complex optimal control problem, and generates flight paths minimizing aircraft noise levels. Operational and safety constraints have been considered and their limits satisfied. Results are here presented and discussed.

  7. Optimization of operational aircraft parameters Reducing Noise Emission

    CERN Document Server

    Abdallah, Lina; Khardi, Salah

    2008-01-01

    The objective of this paper is to develop a model and a minimization method to provide flight path optimums reducing aircraft noise in the vicinity of airports. Optimization algorithm has solved a complex optimal control problem, and generates flight paths minimizing aircraft noise levels. Operational and safety constraints have been considered and their limits satisfied. Results are here presented and discussed.

  8. New opportunities for aircraft noise policy in the Netherlands

    NARCIS (Netherlands)

    Kroesen, M.

    2010-01-01

    This papers aims (1) to provide a review of the (non-acoustic) social-psychological determinants of aircraft noise annoyance, (2) evaluate Schiphol’s noise policy from a social-psychological perspective and (3) review a governance model that can effectively address non-acoustic factors in aircraft n

  9. Conceptual Design of New Low-Noise Aircraft

    OpenAIRE

    Bertsch, Lothar

    2015-01-01

    Noise levels generated by aircraft (and rotorcraft) can be assigned to the loudest noise sources of our times. Sound pressure levels close to a jet aircraft engine under take‐off conditions can reach the human threshold of pain with respect to noise. Aircraft ground noise levels comparable to a heavy truck passing by, i.e. maximum levels in the order of 70 to 80 dBA, can still be measured at large distances up to 20 kilometers away from the actual airport premises (FUSSNOTE: website http:/...

  10. A measurement model for general noise reaction in response to aircraft noise

    NARCIS (Netherlands)

    Kroesen, M.; Schreckenberg, D.

    2011-01-01

    In this paper a measurement model for general noise reaction (GNR) in response to aircraft noise is developed to assess the performance of aircraft noise annoyance and a direct measure of general reaction as indicators of this concept. For this purpose GNR is conceptualized as a superordinate latent

  11. Aircraft noise in the region of the Bucharest-Otopeni Airport. [noise pollution in airport environment

    Science.gov (United States)

    Costescu, M.; Gherghel, C.; Curtoglu, A.

    1974-01-01

    Aircraft noise, especially in the region adjoining airports, constitutes a problem that will be aggravated in the near future because of increasing aircraft traffic and the appearance of new types of large tonnage aircraft with continuously increasing powers and speeds. Criteria for the evaluation of aircraft noise are reported and some results of studies carried out in the region of Bucharest-Otopeni Airport are detailed.

  12. Optimal approach minimizing aircraft noise and fuel consumption

    OpenAIRE

    Khardi, Salah; Abdallah, Lina; Houacine, Mohamed; KONOVALOVA, Olena

    2010-01-01

    The objective of this paper is to develop a model to find and evaluate optimal flight paths in order to minimize aircraft noise levels around airports and fuel consumption. Aircraft flight dynamics and trajectories have been considered. A continuous descent approach has been found to be the optimal approach procedure minimizing noise levels and fuel consumption. Performance of optimal approach procedure and its comparison to Integrated Noise Model standard procedures have been presented and d...

  13. NASA's Aeroacoustic Tools and Methods for Analysis of Aircraft Noise

    Science.gov (United States)

    Rizzi, Stephen A.; Lopes, Leonard V.; Burley, Casey L.

    2015-01-01

    Aircraft community noise is a significant concern due to continued growth in air traffic, increasingly stringent environmental goals, and operational limitations imposed by airport authorities. The ability to quantify aircraft noise at the source and ultimately at observers is required to develop low noise aircraft designs and flight procedures. Predicting noise at the source, accounting for scattering and propagation through the atmosphere to the observer, and assessing the perception and impact on a community requires physics-based aeroacoustics tools. Along with the analyses for aero-performance, weights and fuel burn, these tools can provide the acoustic component for aircraft MDAO (Multidisciplinary Design Analysis and Optimization). Over the last decade significant progress has been made in advancing the aeroacoustic tools such that acoustic analyses can now be performed during the design process. One major and enabling advance has been the development of the system noise framework known as Aircraft NOise Prediction Program2 (ANOPP2). ANOPP2 is NASA's aeroacoustic toolset and is designed to facilitate the combination of acoustic approaches of varying fidelity for the analysis of noise from conventional and unconventional aircraft. The toolset includes a framework that integrates noise prediction and propagation methods into a unified system for use within general aircraft analysis software. This includes acoustic analyses, signal processing and interfaces that allow for the assessment of perception of noise on a community. ANOPP2's capability to incorporate medium fidelity shielding predictions and wind tunnel experiments into a design environment is presented. An assessment of noise from a conventional and Hybrid Wing Body (HWB) aircraft using medium fidelity scattering methods combined with noise measurements from a model-scale HWB recently placed in NASA's 14x22 wind tunnel are presented. The results are in the form of community noise metrics and

  14. Aircraft noise reduction technology. [to show impact on individuals and communities, component noise sources, and operational procedures to reduce impact

    Science.gov (United States)

    1973-01-01

    Aircraft and airport noise reduction technology programs conducted by NASA are presented. The subjects discussed are: (1) effects of aircraft noise on individuals and communities, (2) status of aircraft source noise technology, (3) operational procedures to reduce the impact of aircraft noise, and (4) NASA relations with military services in aircraft noise problems. References to more detailed technical literature on the subjects discussed are included.

  15. A model based monitoring system for aircraft noise

    NARCIS (Netherlands)

    Berg, F. van den; Eisses, A.R.; Beek, P.J.G. van

    2008-01-01

    A new approach for an airport noise monitoring system is presented that comprises not only a number of measuring stations, but also a dedicated sound propagation model and an aircraft noise emission model. This approach enables estimation of noise levels in the whole area around the airport and not

  16. Recent Progress in Engine Noise Reduction for Commercial Aircraft Applications

    Science.gov (United States)

    Huff, Dennis L.

    2003-01-01

    Considerable progress has been made over the past ten years developing technologies for reducing aircraft noise. Engine noise continues to be a dominate source, particularly for aircraft departing from airports. Research efforts have concentrated on developing noise prediction methods, experimental validation, and developing noise reduction concepts that have been verified through model scale and static engine tests. Most of the work has concentrated on fan and jet components for commercial turbofan engines. In this seminar, an overview of the engine noise reduction work that was sponsored by NASA s Advanced Subsonic Technology Noise Reduction Program will be given, along with background information on turbofan noise sources and certification procedures. Concepts like "chevron" nozzles for jet noise reduction and swept stators for fan noise reduction will be highlighted. A preliminary assessment on how the new technologies will impact future engines will be given.

  17. Valuing Aircraft Noise: Stated Choice Experiments Reflecting Inter-Temporal Noise Changes from Airport Relocation

    OpenAIRE

    Thanos, S.; Wardman, M.; Bristow, A. L.

    2011-01-01

    The relocation of Athens Airport provided a rare experimental context in which residents experienced significant changes in noise levels due to the introduction or removal of aircraft noise. This paper reports the results from surveys around both airport locations, using stated choice experiments to estimate values for aircraft noise. The respondents were offered actual inter-temporal noise change scenarios rather than hypothetical variations, which is uncommon in the literature, incorporatin...

  18. Analysis and Synthesis of Tonal Aircraft Noise Sources

    Science.gov (United States)

    Allen, Matthew P.; Rizzi, Stephen A.; Burdisso, Ricardo; Okcu, Selen

    2012-01-01

    Fixed and rotary wing aircraft operations can have a significant impact on communities in proximity to airports. Simulation of predicted aircraft flyover noise, paired with listening tests, is useful to noise reduction efforts since it allows direct annoyance evaluation of aircraft or operations currently in the design phase. This paper describes efforts to improve the realism of synthesized source noise by including short term fluctuations, specifically for inlet-radiated tones resulting from the fan stage of turbomachinery. It details analysis performed on an existing set of recorded turbofan data to isolate inlet-radiated tonal fan noise, then extract and model short term tonal fluctuations using the analytic signal. Methodologies for synthesizing time-variant tonal and broadband turbofan noise sources using measured fluctuations are also described. Finally, subjective listening test results are discussed which indicate that time-variant synthesized source noise is perceived to be very similar to recordings.

  19. NASA Glenn's Contributions to Aircraft Engine Noise Research

    Science.gov (United States)

    Huff, Dennis L.

    2014-01-01

    This presentation reviews engine noise research conducted at the NASA Glenn Research Center over the past 70 years. This report includes a historical perspective of the Center and the facilities used to conduct the research. Major noise research programs are highlighted to show their impact on industry and on the development of aircraft noise reduction technology. Noise reduction trends are discussed, and future aircraft concepts are presented. Since the 1960s, research results show that the average perceived noise level has been reduced by about 20 decibels (dB). Studies also show that, depending on the size of the airport, the aircraft fleet mix, and the actual growth in air travel, another 15 to 17 dB reduction will be required to achieve NASAs long-term goal of providing technologies to limit objectionable noise to the boundaries of an average airport.

  20. Laboratory and community studies of aircraft noise effects

    Science.gov (United States)

    Stephens, D. G.; Powell, C. A.

    1978-01-01

    The noise effects programs objective is to develop aircraft noise criteria and noise reduction methods for achieving greater community and passenger acceptance of air transportation systems. The approach consists of laboratory tests to subjectively evaluate the properties of aircraft-generated noise that are responsible for causing annoyance and field surveys to study the broader problems of community and passenger acceptability. The program is organized into two major thrusts: community acceptance and passenger acceptance. The community acceptance includes subjective response studies of single and multiple aircraft overflights as well as longer term community noise exposure. Emphasis is on the development of units and indices which accurately quantify annoyance. The passenger acceptance program includes studies to determine acceptably levels of interior noise and vibration for speech intelligibility and comfort of crew and passengers. Selected results from several recent studies are presented to indicate the nature, scope, and methods of the research program.

  1. Method and System for Active Noise Control of Tiltrotor Aircraft

    Science.gov (United States)

    Betzina, Mark D. (Inventor); Nguyen, Khanh Q. (Inventor)

    2003-01-01

    Methods and systems for reducing noise generated by rotating blades of a tiltrotor aircraft. A rotor-blade pitch angle associated with the tiltrotor aircraft can be controlled utilizing a swashplate connected to rotating blades of the tiltrotor aircraft. One or more Higher Harmonic Control (HHC) signals can be transmitted and input to a swashplate control actuator associated with the swashplate. A particular blade pitch oscillation (e.g., four cycles per revolution) is there-after produced in a rotating frame of reference associated with the rotating blades in response to input of an HHC signal to the swashplate control actuator associated with the swashplate to thereby reduce noise associated with the rotating blades of the tiltrotor aircraft. The HHC signal can be transmitted and input to the swashplate control actuator to reduce noise of the tiltrotor aircraft in response to a user input utilizing an open-loop configuration.

  2. The Parametric Aircraft Noise Analysis Module - status overview and recent applications

    OpenAIRE

    Bertsch, Lothar; Guerin, Sebastien; Looye, Gertjan; Pott-Polenske, Michael

    2011-01-01

    The German Aerospace Center (DLR) is investigating aircraft noise prediction and noise reduction capabilities. The Parametric Aircraft Noise Analysis Module (PANAM) is a fast prediction tool by the DLR Institute of Aerodynamics and Flow Technology to address overall aircraft noise. It was initially developed to (1) enable comparative design studies with respect to overall aircraft ground noise and to (2) indentify promising low-noise technologies at early aircraft design stages. A brief surve...

  3. Active structural acoustic control of aircraft interior flow noise via the use of active trim panels

    OpenAIRE

    Mahnken, Brian W.

    1996-01-01

    Modem jet aircraft interior noise can be categorized into two main types: tonal noise caused by engine imbalance or blade passage, and mid frequency broadband noise resulting from turbulent flow. This project addresses aircraft interior flow noise caused by a flow separation over the crown of the aircraft. The noise control approach is to mount piezoelectric actuators to the aircraft interior cockpit crown trim panel and use them to actively control aircraft interior noise with...

  4. New opportunities for aircraft noise policy in the Netherlands

    OpenAIRE

    Kroesen, M.

    2010-01-01

    This papers aims (1) to provide a review of the (non-acoustic) social-psychological determinants of aircraft noise annoyance, (2) evaluate Schiphol’s noise policy from a social-psychological perspective and (3) review a governance model that can effectively address non-acoustic factors in aircraft noise policy. It is concluded that the insights in the psychology of noise annoyance inform us that local actors in the relationship ‘airport-environment’ should have the means to adjust to each oth...

  5. Aircraft noise footprint for Bucharest – Sophia flights

    OpenAIRE

    Luis MELIVEO; Nico van OOSTEN; Luminita DRAGASANU

    2012-01-01

    Studies of impact noise have traditionally focused on landing and takeoff procedures in the airports vicinity. Beside these studies, en-route noise is considered an issue when we talk about noise in natural reservation or other populated sensitive areas and when it comes to designing a new aircraft engine. In these cases, the studies are focusing on the impact at ground level of the en route noise produced by aircraft at all the flights stages. This paper presents the results of the measureme...

  6. Cultural theory and aircraft noise policy in the Netherlands

    OpenAIRE

    Kroesen, M.; Huys, M.

    2009-01-01

    In this paper we apply cultural theory to understand the constitution of aircraft noise policy at Amsterdam Schiphol, the largest airport in the Netherlands. In line with Smit and Van Gunsteren (1997) this constitution is identified as an alliance between the hierarchical and egalitarian way of life. We show that this alliance has several weaknesses, in part, because it marginalizes the individualistic way of life. Given the nature of human response to aircraft noise the individualistic way o...

  7. Aircraft noise effects on sleep: Mechanisms, mitigation and research needs

    Directory of Open Access Journals (Sweden)

    Mathias Basner

    2010-01-01

    Full Text Available There is an ample number of laboratory and field studies which provide sufficient evidence that aircraft noise disturbs sleep and, depending on traffic volume and noise levels, may impair behavior and well-being during the day. Although clinical sleep disorders have been shown to be associated with increased risk of cardiovascular diseases, only little is known about the long-term effects of aircraft noise disturbed sleep on health. National and international laws and guidelines try to limit aircraft noise exposure facilitating active and passive noise control to prevent relevant sleep disturbances and its consequences. Adopting the harmonized indicator of the European Union Directive 2002/49/EC, the WHO Night Noise Guideline for Europe (NNG defines four Lnight , outside ranges associated with different risk levels of sleep disturbance and other health effects ( 55 dBA. Although traffic patterns differing in number and noise levels of events that lead to varying degrees of sleep disturbance may result in the same Lnight , simulations of nights with up to 200 aircraft noise events per night nicely corroborate expert opinion guidelines formulated in WHO′s NNG. In the future, large scale field studies on the effects of nocturnal (aircraft noise on sleep are needed. They should involve representative samples of the population including vulnerable groups like children and chronically ill subjects. Optimally, these studies are prospective in nature and examine the long-term consequences of noise-induced sleep disturbances. Furthermore, epidemiological case-control studies on the association of nocturnal (aircraft noise exposure and cardiovascular disease are needed. Despite the existing gaps in knowledge on long-term health effects, sufficient data are available for defining limit values, guidelines and protection concepts, which should be updated with the availability of new data.

  8. The passive and active noise control strategy in the aircraft interior noise

    OpenAIRE

    Paonessa, A.

    1994-01-01

    The stringent comfort requirements that the airliners are providing to the aircraft manufacturers, also for the small regional commuter are increasing the attention of the aircraft designer to the aircraft interior noise performance. The research on the design methodologies is very much improved in the last years providing new materials and new system like the active noise control usefull to get a more comfortable interior and achieve a large competition on the market. In this paper a general...

  9. On Noise Assessment for Blended Wing Body Aircraft

    Science.gov (United States)

    Guo, Yueping; Burley, Casey L; Thomas, Russell H.

    2014-01-01

    A system noise study is presented for the blended-wing-body (BWB) aircraft configured with advanced technologies that are projected to be available in the 2025 timeframe of the NASA N+2 definition. This system noise assessment shows that the noise levels of the baseline configuration, measured by the cumulative Effective Perceived Noise Level (EPNL), have a large margin of 34 dB to the aircraft noise regulation of Stage 4. This confirms the acoustic benefits of the BWB shielding of engine noise, as well as other projected noise reduction technologies, but the noise margins are less than previously published assessments and are short of meeting the NASA N+2 noise goal. In establishing the relevance of the acoustic assessment framework, the design of the BWB configuration, the technical approach of the noise analysis, the databases and prediction tools used in the assessment are first described and discussed. The predicted noise levels and the component decomposition are then analyzed to identify the ranking order of importance of various noise components, revealing the prominence of airframe noise, which holds up the levels at all three noise certification locations and renders engine noise reduction technologies less effective. When projected airframe component noise reduction is added to the HWB configuration, it is shown that the cumulative noise margin to Stage 4 can reach 41.6 dB, nearly at the NASA goal. These results are compared with a previous NASA assessment with a different study framework. The approaches that yield projections of such low noise levels are discussed including aggressive assumptions on future technologies, assumptions on flight profile management, engine installation, and component noise reduction technologies. It is shown that reliable predictions of component noise also play an important role in the system noise assessment. The comparisons and discussions illustrate the importance of practical feasibilities and constraints in aircraft

  10. Potential for Landing Gear Noise Reduction on Advanced Aircraft Configurations

    Science.gov (United States)

    Thomas, Russell H.; Nickol, Craig L.; Burley, Casey L.; Guo, Yueping

    2016-01-01

    The potential of significantly reducing aircraft landing gear noise is explored for aircraft configurations with engines installed above the wings or the fuselage. An innovative concept is studied that does not alter the main gear assembly itself but does shorten the main strut and integrates the gear in pods whose interior surfaces are treated with acoustic liner. The concept is meant to achieve maximum noise reduction so that main landing gears can be eliminated as a major source of airframe noise. By applying this concept to an aircraft configuration with 2025 entry-into-service technology levels, it is shown that compared to noise levels of current technology, the main gear noise can be reduced by 10 EPNL dB, bringing the main gear noise close to a floor established by other components such as the nose gear. The assessment of the noise reduction potential accounts for design features for the advanced aircraft configuration and includes the effects of local flow velocity in and around the pods, gear noise reflection from the airframe, and reflection and attenuation from acoustic liner treatment on pod surfaces and doors. A technical roadmap for maturing this concept is discussed, and the possible drag increase at cruise due to the addition of the pods is identified as a challenge, which needs to be quantified and minimized possibly with the combination of detailed design and application of drag reduction technologies.

  11. Aircraft noise footprint for Bucharest – Sophia flights

    Directory of Open Access Journals (Sweden)

    Luis MELIVEO

    2012-12-01

    Full Text Available Studies of impact noise have traditionally focused on landing and takeoff procedures in the airports vicinity. Beside these studies, en-route noise is considered an issue when we talk about noise in natural reservation or other populated sensitive areas and when it comes to designing a new aircraft engine. In these cases, the studies are focusing on the impact at ground level of the en route noise produced by aircraft at all the flights stages. This paper presents the results of the measurement performed for an A320 aircraft when flying en-route and the impact map for a flight from Bucharest – Sofia – Bucharest (OTP-SOF-OTP.

  12. Investigation of the relationship between aircraft noise and community annoyance in China

    OpenAIRE

    Di Guoqing; Liu Xiaoyi; Shi Xiang; Li Zhengguang; Lin Qili

    2012-01-01

    A survey of community annoyance induced by aircraft noise exposure was carried out around Hangzhou Xiaoshan International Airport. To investigate the relationship curves between aircraft noise and the percentage of "highly annoyed" persons in China and also to get annoyance threshold of aircraft noise in China. Noise annoyance induced by aircraft noise exposure was assessed by 764 local residents around the airport using the International Commission on Biological Effect of Noise (ICBEN) scale...

  13. Device and Method for Reducing Aircraft Noise

    Science.gov (United States)

    Streett, Craig L. (Inventor); Lin, John C. (Inventor)

    2002-01-01

    A noise abatement device that is positioned adjacent to a body. The noise abatement device generally includes tabs or cavities which thicken the shear layer created by fluid flow over, around, or near the body, by creating horseshoe-shaped vortices; this thickening of the shear layer reduces the strength of fluctuations in the flow which produce noise.

  14. The psychological cost of aircraft noise for children.

    Science.gov (United States)

    Bullinger, M; Hygge, S; Evans, G W; Meis, M; von Mackensen, S

    1999-08-01

    Psychological effects of aircraft noise exposure on children have only recently been addressed in the References. The current study took advantage of a natural experiment caused by the opening of a major new airport, exposing children in a formerly quiet area to aircraft noise. In this prospective longitudinal investigation, which employed non-exposed control groups, effects of aircraft noise prior to and subsequent to inauguration of the new airport as well as effects of chronic noise and its reduction at the old airport (6 and 18 month post relocation), were studied in 326 children aged 9 to 13 years. The psychological health of children was investigated with a standardized quality of life scale as well as with a motivational measure derived from the Glass and Singer stress aftereffects paradigm. In addition a self report noise annoyance scale was used. In the children studied at the two airports over three time points, results showed a significant decrease of total quality of life 18 month after aircraft noise exposure as well as a motivational deficits operationalized by fewer attempts to solve insoluble puzzles in the new airport area. Parallel shifts in children's attributions for failure were also noted. At the old airport parallel impairments were present before the airport relocation but subsided there after. These findings are in accord with reports of impaired psychological health after noise exposure and indicate the relevance of monitoring psychological parameters as a function of environmental stressors among children. PMID:10507123

  15. Practical Ranges of Loudness Levels of Various Types of Environmental Noise, Including Traffic Noise, Aircraft Noise, and Industrial Noise

    Directory of Open Access Journals (Sweden)

    Sabine A. Janssen

    2011-05-01

    Full Text Available In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a noise signal varies considerably with the shape of the frequency spectrum of the noise signal. In particular the bandwidth of the spectrum has a large effect on the loudness level, due to the effect of critical bands in the human hearing system. The low-frequency content of the spectrum also has an effect on the loudness level. In this note the relation between loudness level and A-weighted sound level is analyzed for various environmental noise spectra, including spectra of traffic noise, aircraft noise, and industrial noise. From loudness levels calculated for these environmental noise spectra, diagrams are constructed that show the relation between loudness level, A‑weighted sound level, and shape of the spectrum. The diagrams show that the upper limits of the loudness level for broadband environmental noise spectra are about 20 to 40 phon higher than the lower limits for narrowband spectra, which correspond to the loudness levels of pure tones. The diagrams are useful for assessing limitations and potential improvements of environmental noise control methods and policy based on A-weighted sound levels.

  16. Practical ranges of loudness levels of various types of environmental noise, including traffic noise, aircraft noise, and industrial noise.

    Science.gov (United States)

    Salomons, Erik M; Janssen, Sabine A

    2011-06-01

    In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a noise signal varies considerably with the shape of the frequency spectrum of the noise signal. In particular the bandwidth of the spectrum has a large effect on the loudness level, due to the effect of critical bands in the human hearing system. The low-frequency content of the spectrum also has an effect on the loudness level. In this note the relation between loudness level and A-weighted sound level is analyzed for various environmental noise spectra, including spectra of traffic noise, aircraft noise, and industrial noise. From loudness levels calculated for these environmental noise spectra, diagrams are constructed that show the relation between loudness level, A-weighted sound level, and shape of the spectrum. The diagrams show that the upper limits of the loudness level for broadband environmental noise spectra are about 20 to 40 phon higher than the lower limits for narrowband spectra, which correspond to the loudness levels of pure tones. The diagrams are useful for assessing limitations and potential improvements of environmental noise control methods and policy based on A-weighted sound levels. PMID:21776205

  17. Aircraft noise and incidence of hypertension--gender specific effects.

    Science.gov (United States)

    Eriksson, Charlotta; Bluhm, Gösta; Hilding, Agneta; Ostenson, Claes-Göran; Pershagen, Göran

    2010-11-01

    Recent studies show associations between aircraft noise and cardiovascular outcomes such as hypertension. However, these studies were mostly cross-sectional and there are uncertainties regarding potential gender differences as well as sensitive subgroups. In this study, we investigated the cumulative incidence of hypertension in relation to aircraft noise exposure among Swedish men and women living in Stockholm County. A total of 4721 subjects, aged 35-56 at baseline, were followed for 8-10 years. The population was selected according to family history of diabetes, which was present for half of the subjects. The exposure assessment was performed by geographical information systems and based on residential history during the period of follow-up. Blood pressure was measured at baseline and at the end of follow-up. Additional information regarding diagnosis and treatment of hypertension as well as various lifestyle factors was provided by questionnaires. In the overall population, no increased risk for hypertension was found among subjects exposed to aircraft noise ≥ 50 dB(A) L(den); relative risk (RR) 1.02 (95% CI 0.90-1.15). When restricting the cohort to those not using tobacco at the blood pressure measurements, a significant risk increase per 5 dB(A) of aircraft noise exposure was found in men; RR 1.21 (1.05-1.39), but not in women; RR 0.97 (0.83-1.13). In both sexes combined, an increased risk of hypertension related to aircraft noise exposure was indicated primarily among those reporting annoyance to aircraft noise; RR 1.42 (1.11-1.82). No consistent effect modification was detected for any of the cardiovascular risk factors under investigation although a family history of diabetes appeared to modify the risk in women. In conclusion, the results suggest an increased risk of hypertension following long-term aircraft noise exposure in men, and that subjects annoyed by aircraft noise may be particularly sensitive to noise related hypertension. PMID:20880521

  18. The effect of interior aircraft noise on pilot performance.

    Science.gov (United States)

    Lindvall, Johan; Västfjall, Daniel

    2013-04-01

    This study examined the effect of the interior sounds of an aircraft cockpit on ratings of affect and expected performance decrement. While exposed to 12 interior aircraft sounds, of which half were modified to correspond to what is experienced with an active noise reduction (ANR) headset, 23 participants rated their affective reactions and how they believed their performance on various tasks would be affected. The results suggest that implementation of ANR-technique has a positive effect on ratings of expected performance. In addition, affective reactions to the noise are related to ratings of expected performance. The implications of these findings for both research and pilot performance are discussed. PMID:24032324

  19. Synthesis of Virtual Environments for Aircraft Community Noise Impact Studies

    Science.gov (United States)

    Rizzi, Stephen A.; Sullivan, Brenda M.

    2005-01-01

    A new capability has been developed for the creation of virtual environments for the study of aircraft community noise. It is applicable for use with both recorded and synthesized aircraft noise. When using synthesized noise, a three-stage process is adopted involving non-real-time prediction and synthesis stages followed by a real-time rendering stage. Included in the prediction-based source noise synthesis are temporal variations associated with changes in operational state, and low frequency fluctuations that are present under all operating conditions. Included in the rendering stage are the effects of spreading loss, absolute delay, atmospheric absorption, ground reflections, and binaural filtering. Results of prediction, synthesis and rendering stages are presented.

  20. Noise Scaling and Community Noise Metrics for the Hybrid Wing Body Aircraft

    Science.gov (United States)

    Burley, Casey L.; Brooks, Thomas F.; Hutcheson, Florence V.; Doty, Michael J.; Lopes, Leonard V.; Nickol, Craig L.; Vicroy, Dan D.; Pope, D. Stuart

    2014-01-01

    An aircraft system noise assessment was performed for the hybrid wing body aircraft concept, known as the N2A-EXTE. This assessment is a result of an effort by NASA to explore a realistic HWB design that has the potential to substantially reduce noise and fuel burn. Under contract to NASA, Boeing designed the aircraft using practical aircraft design princip0les with incorporation of noise technologies projected to be available in the 2020 timeframe. NASA tested 5.8% scale-mode of the design in the NASA Langley 14- by 22-Foot Subsonic Tunnel to provide source noise directivity and installation effects for aircraft engine and airframe configurations. Analysis permitted direct scaling of the model-scale jet, airframe, and engine shielding effect measurements to full-scale. Use of these in combination with ANOPP predictions enabled computations of the cumulative (CUM) noise margins relative to FAA Stage 4 limits. The CUM margins were computed for a baseline N2A-EXTE configuration and for configurations with added noise reduction strategies. The strategies include reduced approach speed, over-the-rotor line and soft-vane fan technologies, vertical tail placement and orientation, and modified landing gear designs with fairings. Combining the inherent HWB engine shielding by the airframe with added noise technologies, the cumulative noise was assessed at 38.7 dB below FAA Stage 4 certification level, just 3.3 dB short of the NASA N+2 goal of 42 dB. This new result shows that the NASA N+2 goal is approachable and that significant reduction in overall aircraft noise is possible through configurations with noise reduction technologies and operational changes.

  1. NASTRAN application for the prediction of aircraft interior noise

    Science.gov (United States)

    Marulo, Francesco; Beyer, Todd B.

    1987-08-01

    The application of a structural-acoustic analogy within the NASTRAN finite element program for the prediction of aircraft interior noise is presented. Some refinements of the method, which reduce the amount of computation required for large, complex structures, are discussed. Also, further improvements are proposed and preliminary comparisons with structural and acoustic modal data obtained for a large, composite cylinder are presented.

  2. A trade-off analysis design tool. Aircraft interior noise-motion/passenger satisfaction model

    Science.gov (United States)

    Jacobson, I. D.

    1977-01-01

    A design tool was developed to enhance aircraft passenger satisfaction. The effect of aircraft interior motion and noise on passenger comfort and satisfaction was modelled. Effects of individual aircraft noise sources were accounted for, and the impact of noise on passenger activities and noise levels to safeguard passenger hearing were investigated. The motion noise effect models provide a means for tradeoff analyses between noise and motion variables, and also provide a framework for optimizing noise reduction among noise sources. Data for the models were collected onboard commercial aircraft flights and specially scheduled tests.

  3. A study of interior noise levels, noise sources and transmission paths in light aircraft

    Science.gov (United States)

    Hayden, R. E.; Murray, B. S.; Theobald, M. A.

    1983-01-01

    The interior noise levels and spectral characteristics of 18 single-and twin-engine propeller-driven light aircraft, and source-path diagnosis of a single-engine aircraft which was considered representative of a large part of the fleet were studied. The purpose of the flight surveys was to measure internal noise levels and identify principal noise sources and paths under a carefully controlled and standardized set of flight procedures. The diagnostic tests consisted of flights and ground tests in which various parts of the aircraft, such as engine mounts, the engine compartment, exhaust pipe, individual panels, and the wing strut were instrumented to determine source levels and transmission path strengths using the transfer function technique. Predominant source and path combinations are identified. Experimental techniques are described. Data, transfer function calculations to derive source-path contributions to the cabin acoustic environment, and implications of the findings for noise control design are analyzed.

  4. Optimised Sound Absorbing Trim Panels for the Reduction of Aircraft Cabin Noise

    NARCIS (Netherlands)

    Hannink, M.H.C.; Wijnant, Y.H.; Boer, de A.

    2004-01-01

    The EU project FACE (Friendly Aircraft Cabin Environment) aims to improve the environmental comfort in aircraft cabins. As part of this project, this paper focuses on the reduction of noise in aircraft cabins. For modern aircraft flying at cruise conditions, this cabin noise is known to be dominated

  5. Airframe Noise from a Hybrid Wing Body Aircraft Configuration

    Science.gov (United States)

    Hutcheson, Florence V.; Spalt, Taylor B.; Brooks, Thomas F.; Plassman, Gerald E.

    2016-01-01

    A high fidelity aeroacoustic test was conducted in the NASA Langley 14- by 22-Foot Subsonic Tunnel to establish a detailed database of component noise for a 5.8% scale HWB aircraft configuration. The model has a modular design, which includes a drooped and a stowed wing leading edge, deflectable elevons, twin verticals, and a landing gear system with geometrically scaled wheel-wells. The model is mounted inverted in the test section and noise measurements are acquired at different streamwise stations from an overhead microphone phased array and from overhead and sideline microphones. Noise source distribution maps and component noise spectra are presented for airframe configurations representing two different approach flight conditions. Array measurements performed along the aircraft flyover line show the main landing gear to be the dominant contributor to the total airframe noise, followed by the nose gear, the inboard side-edges of the LE droop, the wing tip/LE droop outboard side-edges, and the side-edges of deployed elevons. Velocity dependence and flyover directivity are presented for the main noise components. Decorrelation effects from turbulence scattering on spectral levels measured with the microphone phased array are discussed. Finally, noise directivity maps obtained from the overhead and sideline microphone measurements for the landing gear system are provided for a broad range of observer locations.

  6. Aircraft noise effects: An interdisciplinary study of the effect of aircraft noise on man. Part 2: Appendix

    Science.gov (United States)

    1980-01-01

    A survey used to obtain data of a sociological nature regarding subjects used in a study of aircraft noise perception and tolerance near the Munich-Reims airport is presented. Statistics compiled on occupational, physiological, and medical aspects of the subjects are tabulated.

  7. The Shadow Price of Aircraft Noise Nuisance

    OpenAIRE

    Van Praag, Bernard M.S.; B.E. Baarsma

    2000-01-01

    This paper has a twofold objective. First, we develop a new method toassess the monetary value for individuals of external effects (viz., aircraftnoise nuisance) which are not or only partly internalized in market prices. The method makes use of an ordinal index of life satisfaction as scored by individual respondents who are subjected in varying intensity to the external effect. Our second objective is to assess, with this method, to what extent noise nuisance effects around Amsterdam Airpor...

  8. Near-field acoustical holography of military jet aircraft noise

    Science.gov (United States)

    Wall, Alan T.; Gee, Kent L.; Neilsen, Tracianne; Krueger, David W.; Sommerfeldt, Scott D.; James, Michael M.

    2010-10-01

    Noise radiated from high-performance military jet aircraft poses a hearing-loss risk to personnel. Accurate characterization of jet noise can assist in noise prediction and noise reduction techniques. In this work, sound pressure measurements were made in the near field of an F-22 Raptor. With more than 6000 measurement points, this is the most extensive near-field measurement of a high-performance jet to date. A technique called near-field acoustical holography has been used to propagate the complex pressure from a two- dimensional plane to a three-dimensional region in the jet vicinity. Results will be shown and what they reveal about jet noise characteristics will be discussed.

  9. Noise of high-performance aircraft at afterburner

    Science.gov (United States)

    Tam, Christopher K. W.; Parrish, Sarah A.

    2015-09-01

    The noise from a high-performance aircraft at afterburner is investigated. The main objective is to determine whether the dominant noise components are the same or similar to those of a hot supersonic laboratory jet. For this purpose, measured noise data from F-22A Raptors are analyzed. It is found, based on both spectral and directivity data, that there is a new dominant noise component in addition to the usual turbulent mixing noise. The characteristic features of the new noise component are identified. Measured data indicates that the new noise component is observed only when the rate of fuel burn of the engine is increased significantly above that of the intermediate power setting. This suggests that the new noise component is combustion related. The possibility that it is indirect combustion noise generated by the passage of hot spots from the afterburner through the nozzle of the jet is investigated. Because flow and temperature data were not measured in the F-22A engine tests, to provide support to the proposition, numerical simulations of indirect combustion noise generation due to the passing of an entropy wave pulse (a hot spot) through a military-style nozzle are carried out. Sound generation is observed at the front and at the back of the pulse. This creates a fast and a slow acoustic wave as the sound radiates out from the nozzle exit. Quantitative estimates of the principal directions of acoustic radiation due to the emitted fast and slow acoustic waves are made. It is found that there are reasonably good agreements with measured data. To estimate the intensity level (IL) of the radiated indirect combustion noise, a time-periodic entropy wave train of 15 percent temperature fluctuation is used as a model of the hot spots coming out of the afterburner. This yields an IL of 175.5 dB. This is a fairly intense noise source, well capable of causing the radiation of the new jet noise component.

  10. On INM's Use of Corrected Net Thrust for the Prediction of Jet Aircraft Noise

    Science.gov (United States)

    McAninch, Gerry L.; Shepherd, Kevin P.

    2011-01-01

    The Federal Aviation Administration s (FAA) Integrated Noise Model (INM) employs a prediction methodology that relies on corrected net thrust as the sole correlating parameter between aircraft and engine operating states and aircraft noise. Thus aircraft noise measured for one set of atmospheric and aircraft operating conditions is assumed to be applicable to all other conditions as long as the corrected net thrust remains constant. This hypothesis is investigated under two primary assumptions: (1) the sound field generated by the aircraft is dominated by jet noise, and (2) the sound field generated by the jet flow is adequately described by Lighthill s theory of noise generated by turbulence.

  11. Aircraft noise calculation and synthesis in a non-standard atmosphere

    NARCIS (Netherlands)

    Arntzen, M.

    2014-01-01

    The atmosphere modifies the emitted sound waves of an aircraft during propagation and is therefore important in the calculation of noise contours or synthesis. Noise contours present the resulting noise levels on the ground and are, as such, often applied for regulatory purposes. Aircraft noise synt

  12. Computation of Engine Noise Propagation and Scattering Off an Aircraft

    Science.gov (United States)

    Xu, J.; Stanescu, D.; Hussaini, M. Y.; Farassat, F.

    2003-01-01

    The paper presents a comparison of experimental noise data measured in flight on a two-engine business jet aircraft with Kulite microphones placed on the suction surface of the wing with computational results. Both a time-domain discontinuous Galerkin spectral method and a frequency-domain spectral element method are used to simulate the radiation of the dominant spinning mode from the engine and its reflection and scattering by the fuselage and the wing. Both methods are implemented in computer codes that use the distributed memory model to make use of large parallel architectures. The results show that trends of the noise field are well predicted by both methods.

  13. Commercial aircraft noise modeling Effects of air traffic and airport infrastructure changes

    OpenAIRE

    Khardi, S.; Konovalova, E.; LADEGAILLERIE, Y; HAMADICHE, M

    2010-01-01

    International air traffic is growing rapidly and environmental concerns induced by excessive aircraft noise become a major objective of airport authorities and aircraft manufacturers despite of the reduction of the aircraft noise levels by 20 dB during the last thirty years. The large numbers of people living in communities near airports, affected by aircraft noise, have been complaining. This paper gives detailed operations data of Lyon Saint-Exupéry International Airport (France) and provid...

  14. Night time aircraft noise exposure and children′s cognitive performance

    OpenAIRE

    Stephen Stansfeld; Staffan Hygge; Charlotte Clark; Tamuno Alfred

    2010-01-01

    Chronic aircraft noise exposure in children is associated with impairment of reading and long-term memory. Most studies have not differentiated between day or nighttime noise exposure. It has been hypothesized that sleep disturbance might mediate the association of aircraft noise exposure and cognitive impairment in children. This study involves secondary analysis of data from the Munich Study and the UK Road Traffic and Aircraft Noise Exposure and Children′s Cognition and Health (RANCH) Stud...

  15. The DEBATS Study: Health effects of aircraft noise near three French airports

    OpenAIRE

    EVRARD, AS; BARTHELEMY, L; CHAMPELOVIER, P; CHIRON, M; JAHI, H; Lambert, J.; Laumon, B.

    2011-01-01

    INTRODUCTION : A national survey carried out in 2005 by INRETS shows that 6.6% of the French population are annoyed by aircraft noise. While many surveys carried out both in France and abroad address aircraft noise annoyance or report adverse effects on sleep quality, much fewer consider at the same time the physiological effects of this noise exposure. OBJECTIVES : DEBATS aims to characterize the relations between aircraft noise exposure and health status of the French population living i...

  16. The relationship between civil aircraft noise and community annoyance in Korea

    Science.gov (United States)

    Lim, Changwoo; Kim, Jaehwan; Hong, Jiyoung; Lee, Soogab; Lee, Soojoo

    2007-01-01

    Studies of community annoyance caused by civil aircraft noise exposure were carried out in 18 areas around Gimpo and Gimhae international airports in order to accumulate social survey data and assess the relationship between aircraft noise levels and annoyance responses in Korea. WECPNL, adopted as the aircraft noise index in Korea, and the percentage of respondents who felt highly annoyed (%HA) have been used to assess the dose-response of aircraft noise. Aircraft noise levels were measured automatically by airport noise monitoring system, B&K type 3597. Social surveys were carried out to people living within 100 m of noise measurement points. The Questionnaire used in the survey contained demographic factors, noise annoyance, interference with daily activities and health-related symptoms. The question relating to the aircraft noise annoyance was answered on an 11-point numerical scale. The randomly selected respondents who were aged between 18 and 70 years completed the questionnaire by themselves. In total, 705 respondents participated in the questionnaire. The results show that WECPNL, noise metric considering characteristics of event and intrusive noise, is more reasonable than L dn, noise metric considering total sound, to assess the effects of aircraft noise on health. It is also shown that the annoyance responses caused by aircraft noise in Korea seems higher than those reported in other countries.

  17. Updating working memory in aircraft noise and speech noise causes different fMRI activations

    OpenAIRE

    Sætrevik, Bjørn; Sörqvist, Patrik

    2014-01-01

    The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between “substitution processes,” which involve adding new items to the working memory representation and suppressing old items, and “exclusion processes,” which involve rejecting new items and maintaining an intact memory set. The cu...

  18. Predicting Noise From Aircraft Turbine-Engine Combustors

    Science.gov (United States)

    Gliebe, P.; Mani, R.; Salamah, S.; Coffin, R.; Mehta, Jayesh

    2005-01-01

    COMBUSTOR and CNOISE are computer codes that predict far-field noise that originates in the combustors of modern aircraft turbine engines -- especially modern, low-gaseous-emission engines, the combustors of which sometimes generate several decibels more noise than do the combustors of older turbine engines. COMBUSTOR implements an empirical model of combustor noise derived from correlations between engine-noise data and operational and geometric parameters, and was developed from databases of measurements of acoustic emissions of engines. CNOISE implements an analytical and computational model of the propagation of combustor temperature fluctuations (hot spots) through downstream turbine stages. Such hot spots are known to give rise to far-field noise. CNOISE is expected to be helpful in determining why low-emission combustors are sometimes noisier than older ones, to provide guidance for refining the empirical correlation model embodied in the COMBUSTOR code, and to provide insight on how to vary downstream turbinestage geometry to reduce the contribution of hot spots to far-field noise.

  19. Investigation of the relationship between aircraft noise and community annoyance in China.

    Science.gov (United States)

    Guoqing, Di; Xiaoyi, Liu; Xiang, Shi; Zhengguang, Li; Qili, Lin

    2012-01-01

    A survey of community annoyance induced by aircraft noise exposure was carried out around Hangzhou Xiaoshan International Airport. To investigate the relationship curves between aircraft noise and the percentage of "highly annoyed" persons in China and also to get annoyance threshold of aircraft noise in China. Noise annoyance induced by aircraft noise exposure was assessed by 764 local residents around the airport using the International Commission on Biological Effect of Noise (ICBEN) scale. The status quo of aircraft noise pollution was measured by setting up 39 monitoring points. The interpolation was used to estimate the weighted effective continuous perceived noise levels (LWECPN) in different areas around the airport, and the graph of equal noise level contour was drawn. The membership function was used to calculate the annoyance threshold of aircraft noise. Data were analyzed using SPSS 16.0 and Origin 8.0. The results showed that if LWECPN was 64.3 dB (Ldn was 51.4 dB), then 15% respondents were highly annoyed. If LWECPN was 68.1 dB (Ldn was 55.0 dB), then 25% respondents were highly annoyed. The annoyance threshold of aircraft noise (LWECPN) was 73.7 dB, while the annoyance threshold of a single flight incident instantaneous noise level (LAmax) was 72.9 dB. People around the airport had felt annoyed before the aircraft noise LWECPN reached the standard limit. PMID:22517304

  20. Investigation of the relationship between aircraft noise and community annoyance in China

    Directory of Open Access Journals (Sweden)

    Di Guoqing

    2012-01-01

    Full Text Available A survey of community annoyance induced by aircraft noise exposure was carried out around Hangzhou Xiaoshan International Airport. To investigate the relationship curves between aircraft noise and the percentage of "highly annoyed" persons in China and also to get annoyance threshold of aircraft noise in China. Noise annoyance induced by aircraft noise exposure was assessed by 764 local residents around the airport using the International Commission on Biological Effect of Noise (ICBEN scale. The status quo of aircraft noise pollution was measured by setting up 39 monitoring points. The interpolation was used to estimate the weighted effective continuous perceived noise levels (LWECPN in different areas around the airport, and the graph of equal noise level contour was drawn. The membership function was used to calculate the annoyance threshold of aircraft noise. Data were analyzed using SPSS 16.0 and Origin 8.0. The results showed that if LWECPN was 64.3 dB (Ldn was 51.4 dB, then 15% respondents were highly annoyed. If LWECPN was 68.1 dB (Ldn was 55.0 dB, then 25% respondents were highly annoyed. The annoyance threshold of aircraft noise (LWECPN was 73.7 dB, while the annoyance threshold of a single flight incident instantaneous noise level (LAmax was 72.9 dB. People around the airport had felt annoyed before the aircraft noise LWECPN reached the standard limit.

  1. Federal Interagency Committee on Aviation Noise (FICAN) Position on Research into Effects of Aircraft Noise on Classroom Learning.

    Science.gov (United States)

    2000

    This symposium report presents a summary of research on the affect of aircraft noise on the classroom environment revealing that aircraft noise can interfere with learning in the following areas: reading, motivation, language and speech acquisition, and memory. The strongest findings are in the area of reading, where more than 20 studies have…

  2. Measuring subjective response to aircraft noise: The effects of survey context

    NARCIS (Netherlands)

    Kroesen, M.; Molin, E.J.E.; Van Wee, G.P.

    2013-01-01

    In applied research, noise annoyance is often used as indicator of subjective reaction to aircraft noise in residential areas. The present study aims to show that the meaning which respondents attach to the concept of aircraft noise annoyance is partly a function of survey context. To this purpose a

  3. Policy discourse, people's internal frames, and declared aircraft noise annoyance: an application of Q-methodology.

    NARCIS (Netherlands)

    Kroesen, M.; Broer, C.

    2009-01-01

    Aircraft noise annoyance is studied extensively, but often without an explicit theoretical framework. In this article, a social approach for noise annoyance is proposed. The idea that aircraft noise is meaningful to people within a socially produced discourse is assumed and tested. More particularly

  4. Measuring subjective response to aircraft noise: the effects of survey context.

    NARCIS (Netherlands)

    Kroesen, M.; Molin, E.J.E.; Wee, B. van

    2013-01-01

    In applied research, noise annoyance is often used as indicator of subjective reaction to aircraft noise in residential areas. The present study aims to show that the meaning which respondents attach to the concept of aircraft noise annoyance is partly a function of survey context. To this purpose a

  5. Aircraft noise calculation and synthesis in a non-standard atmosphere

    OpenAIRE

    Arntzen, M.

    2014-01-01

    The atmosphere modifies the emitted sound waves of an aircraft during propagation and is therefore important in the calculation of noise contours or synthesis. Noise contours present the resulting noise levels on the ground and are, as such, often applied for regulatory purposes. Aircraft noise synthesis is a technique that allows to transform a calculated prediction into audible sound that can be experienced in a virtual reality environment. Noise synthesis techniques allow people to be subj...

  6. Model-based synthesis of aircraft noise to quantify human perception of sound quality and annoyance

    Science.gov (United States)

    Berckmans, D.; Janssens, K.; Van der Auweraer, H.; Sas, P.; Desmet, W.

    2008-04-01

    This paper presents a method to synthesize aircraft noise as perceived on the ground. The developed method gives designers the opportunity to make a quick and economic evaluation concerning sound quality of different design alternatives or improvements on existing aircraft. By presenting several synthesized sounds to a jury, it is possible to evaluate the quality of different aircraft sounds and to construct a sound that can serve as a target for future aircraft designs. The combination of using a sound synthesis method that can perform changes to a recorded aircraft sound together with executing jury tests allows to quantify the human perception of aircraft noise.

  7. On Physical Aeroacoustics with Some Implications for Low-Noise Aircraft Design and Airport Operations

    Directory of Open Access Journals (Sweden)

    Luís M. B. C. Campos

    2015-02-01

    Full Text Available Air traffic is growing at a steady rate of 3% to 5% per year in most regions of the world, implying a doubling every 15–25 years. This requires major advances in aircraft noise reduction at airports, just not to increase the noise exposure due to the larger number of aircraft movements. In fact it can be expected, as a consequence of increased opposition to noise by near airport residents, that the overall noise exposure will have to be reduced, by bans, curfews, fines, and other means and limitations, unless significantly quieter aircraft operations are achieved. The ultimate solution is aircraft operations inaudible outside the airport perimeter, or noise levels below road traffic and other existing local noise sources. These substantial noise reductions cannot come at the expense of a degradation of cruise efficiency, that would affect not just economics and travel time, but would increase fuel consumption and emission of pollutants on a global scale. The paper reviews the: (i current knowledge of the aircraft noise sources; (ii the sound propagation in the atmosphere and ground effects that determine the noise annoyance of near-airport residents; (iii the noise mitigation measures that can be applied to current and future aircraft; (iv the prospects of evolutionary and novel aircraft designs towards quieter aircraft in the near term and eventually to operations inaudible outside the airport perimeter. The 20 figures and 1 diagram with their legends provide a visual summary of the review.

  8. Updating working memory in aircraft noise and speech noise causes different fMRI activations.

    Science.gov (United States)

    Saetrevik, Bjørn; Sörqvist, Patrik

    2015-02-01

    The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between "substitution processes," which involve adding new items to the working memory representation and suppressing old items, and "exclusion processes," which involve rejecting new items and maintaining an intact memory set. The current findings supported the findings of a previous study by showing that substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, whereas exclusion activated the anterior medial frontal cortex. Moreover, the prefrontal cortex was activated more by substitution processes when exposed to background speech than when exposed to aircraft noise. These results indicate that (a) the prefrontal cortex plays a special role when task-irrelevant materials should be denied access to working memory and (b) that, when compensating for different types of noise, either different cognitive mechanisms are involved or those cognitive mechanisms that are involved are involved to different degrees. PMID:25352319

  9. Trends in aircraft noise annoyance: The role of study and sample characteristics

    NARCIS (Netherlands)

    Kroesen, M.; Molin, E.J.E.; Miedema, H.M.E.; Vos, H.; Janssen, S.A.; Wee, B. van

    2010-01-01

    This study assesses the effects of aircraft noise on residential satisfaction, an important indicator of subjective well-being. A structural equation model is specified that estimates the relationships between objective variables, noise annoyance variables and residential satisfaction. Secondary dat

  10. Saliva Cortisol and Exposure to Aircraft Noise in Six European Countries

    OpenAIRE

    Selander, Jenny; Bluhm, Gösta; Theorell, Töres; Pershagen, Göran; Babisch, Wolfgang; Seiffert, Ingeburg; Houthuijs, Danny; Breugelmans, Oscar; Vigna-Taglianti, Federica; Antoniotti, Maria Chiara; Velonakis, Emmanuel; Davou, Elli; Dudley, Marie-Louise; Järup, Lars

    2009-01-01

    Background Several studies show an association between exposure to aircraft or road traffic noise and cardiovascular effects, which may be mediated by a noise-induced release of stress hormones. Objective Our objective was to assess saliva cortisol concentration in relation to exposure to aircraft noise. Method A multicenter cross-sectional study, HYENA (Hypertension and Exposure to Noise near Airports), comprising 4,861 persons was carried out in six European countries. In a subgroup of 439 ...

  11. System Noise Assessment and the Potential for a Low Noise Hybrid Wing Body Aircraft with Open Rotor Propulsion

    Science.gov (United States)

    Thomas, Russell H.; Burley, Casey L.; Lopes, Leonard V.; Bahr, Christopher J.; Gern, Frank H.; VanZante, Dale E.

    2014-01-01

    An aircraft system noise assessment was conducted for a hybrid wing body freighter aircraft concept configured with three open rotor engines. The primary objective of the study was to determine the aircraft system level noise given the significant impact of installation effects including shielding the open rotor noise by the airframe. The aircraft was designed to carry a payload of 100,000 lbs on a 6,500 nautical mile mission. An experimental database was used to establish the propulsion airframe aeroacoustic installation effects including those from shielding by the airframe planform, interactions with the control surfaces, and additional noise reduction technologies. A second objective of the study applied the impacts of projected low noise airframe technology and a projection of advanced low noise rotors appropriate for the NASA N+2 2025 timeframe. With the projection of low noise rotors and installation effects, the aircraft system level was 26.0 EPNLdB below Stage 4 level with the engine installed at 1.0 rotor diameters upstream of the trailing edge. Moving the engine to 1.5 rotor diameters brought the system level noise to 30.8 EPNLdB below Stage 4. At these locations on the airframe, the integrated level of installation effects including shielding can be as much as 20 EPNLdB cumulative in addition to lower engine source noise from advanced low noise rotors. And finally, an additional set of technology effects were identified and the potential impact at the system level was estimated for noise only without assessing the impact on aircraft performance. If these additional effects were to be included it is estimated that the potential aircraft system noise could reach as low as 38.0 EPNLdB cumulative below Stage 4.

  12. Containing Aircraft Noise Levels at take-off: A Mathematical Programming Approach

    OpenAIRE

    Nejjari Akhi-Elarab, Fatiha; Prats Menéndez, Xavier; Puig, Vicenç; Quevedo Casín, Joseba Jokin; Polit, Monique; Ouattara, Baba; Achaibou, Karim; Mora-Camino, Félix

    2005-01-01

    The sustained growth of air transportation traffic along the last decades has induced increasing noise exposure for the areas surrounding large and medium airports. This study concentrates on the optimization of the take-off and departure flight phase for a transportation aircraft. A general aircraft trajectory generation problem is first formulated as an optimal control problem where a global cost, including noise penalties, is to be minimized. Since aircraft operators and communities ...

  13. Workshop on Jet Exhaust Noise Reduction for Tactical Aircraft - NASA Perspective

    Science.gov (United States)

    Huff, Dennis L.; Henderson, Brenda S.

    2007-01-01

    Jet noise from supersonic, high performance aircraft is a significant problem for takeoff and landing operations near air bases and aircraft carriers. As newer aircraft with higher thrust and performance are introduced, the noise tends to increase due to higher jet exhaust velocities. Jet noise has been a subject of research for over 55 years. Commercial subsonic aircraft benefit from changes to the engine cycle that reduce the exhaust velocities and result in significant noise reduction. Most of the research programs over the past few decades have concentrated on commercial aircraft. Progress has been made by introducing new engines with design features that reduce the noise. NASA has recently started a new program called "Fundamental Aeronautics" where three projects (subsonic fixed wing, subsonic rotary wing, and supersonics) address aircraft noise. For the supersonics project, a primary goal is to understand the underlying physics associated with jet noise so that improved noise prediction tools and noise reduction methods can be developed for a wide range of applications. Highlights from the supersonics project are presented including prediction methods for broadband shock noise, flow measurement methods, and noise reduction methods. Realistic expectations are presented based on past history that indicates significant jet noise reduction cannot be achieved without major changes to the engine cycle. NASA s past experience shows a few EPNdB (effective perceived noise level in decibels) can be achieved using low noise design features such as chevron nozzles. Minimal thrust loss can be expected with these nozzles (< 0.5%) and they may be retrofitted on existing engines. In the long term, it is desirable to use variable cycle engines that can be optimized for lower jet noise during takeoff operations and higher thrust for operational performance. It is also suggested that noise experts be included early in the design process for engine nozzle systems to participate

  14. Auralization Architectures for NASA?s Next Generation Aircraft Noise Prediction Program

    Science.gov (United States)

    Rizzi, Stephen A.; Lopes, Leonard V.; Burley, Casey L.; Aumann, Aric R.

    2013-01-01

    Aircraft community noise is a significant concern due to continued growth in air traffic, increasingly stringent environmental goals, and operational limitations imposed by airport authorities. The assessment of human response to noise from future aircraft can only be afforded through laboratory testing using simulated flyover noise. Recent work by the authors demonstrated the ability to auralize predicted flyover noise for a state-of-the-art reference aircraft and a future hybrid wing body aircraft concept. This auralization used source noise predictions from NASA's Aircraft NOise Prediction Program (ANOPP) as input. The results from this process demonstrated that auralization based upon system noise predictions is consistent with, and complementary to, system noise predictions alone. To further develop and validate the auralization process, improvements to the interfaces between the synthesis capability and the system noise tools are required. This paper describes the key elements required for accurate noise synthesis and introduces auralization architectures for use with the next-generation ANOPP (ANOPP2). The architectures are built around a new auralization library and its associated Application Programming Interface (API) that utilize ANOPP2 APIs to access data required for auralization. The architectures are designed to make the process of auralizing flyover noise a common element of system noise prediction.

  15. Combustion noise from gas turbine aircraft engines measurement of far-field levels

    Science.gov (United States)

    Krejsa, Eugene A.

    1987-01-01

    Combustion noise can be a significant contributor to total aircraft noise. Measurement of combustion noise is made difficult by the fact that both jet noise and combustion noise exhibit broadband spectra and peak in the same frequency range. Since in-flight reduction of jet noise is greater than that of combustion noise, the latter can be a major contributor to the in-flight noise of an aircraft but will be less evident, and more difficult to measure, under static conditions. Several methods for measuring the far-field combustion noise of aircraft engines are discussed in this paper. These methods make it possible to measure combustion noise levels even in situations where other noise sources, such as jet noise, dominate. Measured far-field combustion noise levels for several turbofan engines are presented. These levels were obtained using a method referred to as three-signal coherence, requiring that fluctuating pressures be measured at two locations within the engine core in addition to the far-field noise measurement. Cross-spectra are used to separate the far-field combustion noise from far-field noise due to other sources. Spectra and directivities are presented. Comparisons with existing combustion noise predictions are made.

  16. Determining the direction of causality between psychological factors and aircraft noise annoyance

    Directory of Open Access Journals (Sweden)

    Maarten Kroesen

    2010-01-01

    Full Text Available In this paper, an attempt is made to establish the direction of causality between a range of psychological factors and aircraft noise annoyance. For this purpose, a panel model was estimated within a structural equation modeling approach. Data were gathered from two surveys conducted in April 2006 and April 2008, respectively, among the same residents living within the 45 Level day-evening-night contour of Amsterdam Airport Schiphol, the largest airport in the Netherlands (n=250. A surprising result is that none of the paths from the psychological factors to aircraft noise annoyance were found to be significant. Yet 2 effects were significant the other way around: (1 from ′aircraft noise annoyance′ to ′concern about the negative health effects of noise′ and (2 from ′aircraft noise annoyance′ to ′belief that noise can be prevented.′ Hence aircraft noise annoyance measured at time 1 contained information that can effectively explain changes in these 2 variables at time 2, while controlling for their previous values. Secondary results show that (1 aircraft noise annoyance is very stable through time and (2 that changes in aircraft noise annoyance and the identified psychological factors are correlated.

  17. Aircraft Noise, Health, and Residential Sorting: Evidence from Two Quasi-Experiments

    OpenAIRE

    Boes, Stefan; Nüesch, Stephan; Stillman, Steven

    2012-01-01

    We explore two unexpected changes in flight regulations to identify the causal effect of aircraft noise on health. Detailed yearly noise metrics are linked with panel data on health outcomes using exact address information. Controlling for individual and spatial heterogeneity, we find that aircraft noise significantly increases sleeping problems, weariness and headaches. Our pooled models substantially underestimate the detrimental health effects, which suggests that individuals self-select i...

  18. Multi-disciplinary, community-oriented design of low-noise aircraft: the COSMA project

    OpenAIRE

    Iemma Umberto

    2016-01-01

    The EC-funded project COSMA (Community Oriented Solutions to Minimize aircraft noise Annoyance, 7th Framework Programme) started in June 2009 with an ambitious, twofold goal: improve the understanding of the annoyance induced by aircraft noise on the population and identify the engineering guidelines to establish appropriate design strategies and operational procedure to reduce these effects. The project was conceived within the context of the X-Noise Collaborative Net...

  19. Measuring subjective response to aircraft noise: The effects of survey context

    OpenAIRE

    Kroesen, M.; Molin, E.J.E.; Van Wee, G.P.

    2013-01-01

    In applied research, noise annoyance is often used as indicator of subjective reaction to aircraft noise in residential areas. The present study aims to show that the meaning which respondents attach to the concept of aircraft noise annoyance is partly a function of survey context. To this purpose a survey is conducted among residents living near Schiphol Airport, the largest airport in the Netherlands. In line with the formulated hypotheses it is shown that different sets of preceding questi...

  20. Nuisance Caused by Aircraft Noise in the Vicinity of Tehran International Airport

    Directory of Open Access Journals (Sweden)

    Stan Frost

    1999-03-01

    Full Text Available Noise measurement and social questionnaire surveys in three residential areas around Mehrabad International Airport (Tehran, Iran were based upon randomly selected dwellings in each area. A total of 193 individuals responded and many are annoyed and dissatisfied with aircraft noise and in consequence they would like to move. Aircraft noise is the strongest negative environmental factor affecting the residents in the vicinity of Mehrabad Airport and it could be a hazard for their health.

  1. Prediction and reduction of aircraft noise in outdoor environments

    Science.gov (United States)

    Tong, Bao N.

    This dissertation investigates the noise due to an en-route aircraft cruising at high altitudes. It offers an improved understanding into the combined effects of atmospheric propagation, ground reflection, and source motion on the impact of en-route aircraft noise. A numerical model has been developed to compute pressure time-histories due to a uniformly moving source above a flat ground surface in the presence of a horizontally stratified atmosphere. For a moving source at high elevations, contributions from a direct and specularly reflected wave are sufficient in predicting the sound field close to the ground. In the absence of wind effects, the predicted sound field from a single overhead flight trajectory can be used to interpolate pressure time histories at all other receiver locations via a simplified ray model for the incoherent sound field. This approach provides an efficient method for generating pressure time histories in a three-dimensional space for noise impact studies. A variety of different noise propagation methods are adapted to a uniformly moving source to evaluate the accuracy and efficiency of their predictions. The techniques include: analytical methods, the Fast Field Program (FFP), and asymptotic analysis methods (e.g., ray tracing and more advanced formulations). Source motion effects are introduced via either a retarded time analysis or a Lorentz transform approach depending on the complexity of the problem. The noise spectrum from a single emission frequency, moving source has broadband characteristics. This is a consequence of the Doppler shift which continuously modifies the perceived frequency of the source as it moves relative to a stationary observer on the ground. Thus, the instantaneous wavefronts must be considered in both the frequency dependent ground impedance model and the atmospheric absorption model. It can be shown that the Doppler factor is invariant along each ray path. This gives rise to a path dependent atmospheric

  2. Night time aircraft noise exposure and children′s cognitive performance

    Directory of Open Access Journals (Sweden)

    Stephen Stansfeld

    2010-01-01

    Full Text Available Chronic aircraft noise exposure in children is associated with impairment of reading and long-term memory. Most studies have not differentiated between day or nighttime noise exposure. It has been hypothesized that sleep disturbance might mediate the association of aircraft noise exposure and cognitive impairment in children. This study involves secondary analysis of data from the Munich Study and the UK Road Traffic and Aircraft Noise Exposure and Children′s Cognition and Health (RANCH Study sample to test this. In the Munich study, 330 children were assessed on cognitive measures in three measurement waves a year apart, before and after the switchover of airports. Self-reports of sleep quality were analyzed across airports, aircraft noise exposure and measurement wave to test whether changes in nighttime noise exposure had any effect on reported sleep quality, and whether this showed the same pattern as for changes in cognitive performance. For the UK sample of the RANCH study, night noise contour information was linked to the children′s home and related to sleep disturbance and cognitive performance. In the Munich study, analysis of sleep quality questions showed no consistent interactions between airport, noise, and measurement wave, suggesting that poor sleep quality does not mediate the association between noise exposure and cognition. Daytime and nighttime aircraft noise exposure was highly correlated in the RANCH study. Although night noise exposure was significantly associated with impaired reading and recognition memory, once home night noise exposure was centered on daytime school noise exposure, night noise had no additional effect to daytime noise exposure. These analyses took advantage of secondary data available from two studies of aircraft noise and cognition. They were not initially designed to examine sleep disturbance and cognition, and thus, there are methodological limitations which make it less than ideal in giving

  3. Reduction of commercial aircraft noise emission around airports. A new environmental challenge

    OpenAIRE

    Khardi, Salah

    2009-01-01

    Noise abatement procedures (NAPs) are considered as a necessary measure for a balanced approach of noise control around airports. Their correct implementation depends upon many factors, which vary in operation and influence the efficiency of the NAPs. Any system, which defines the correct features of the NAPs for particular aircraft in specific conditions, would be useful for noise control. Thus, implementation of noise level monitoring systems, currently used around airports, gives a noise m...

  4. Policy discourse, people’s internal frames, and declared aircraft noise annoyance: An application of Q-methodology

    OpenAIRE

    Kroesen, M.; Bröer, C.

    2009-01-01

    Aircraft noise annoyance is studied extensively, but often without an explicit theoretical framework. In this article, a social approach for noise annoyance is proposed. The idea that aircraft noise is meaningful to people within a socially produced discourse is assumed and tested. More particularly, it is expected that the noise policy discourse influences people’s assessment of aircraft noise. To this end, Q-methodology is used, which, to the best of the authors’ knowledge, has not been use...

  5. Policy discourse and people's internal frames, and declared aircraft noise annoyance: an application of Q-methodology

    OpenAIRE

    Kroesen, M.; Bröer, C.

    2009-01-01

    Aircraft noise annoyance is studied extensively, but often without an explicit theoretical framework. In this article, a social approach for noise annoyance is proposed. The idea that aircraft noise is meaningful to people within a socially produced discourse is assumed and tested. More particularly, it is expected that the noise policy discourse influences people's assessment of aircraft noise. To this end, Q-methodology is used, which, to the best of the authors' knowledge, has not been use...

  6. MPT Prediction of Aircraft-Engine Fan Noise

    Science.gov (United States)

    Connell, Stuart D.

    2004-01-01

    A collection of computer programs has been developed that implements a procedure for predicting multiple-pure-tone (MPT) noise generated by fan blades of an aircraft engine (e.g., a turbofan engine). MPT noise arises when the fan is operating with supersonic relative tip Mach No. Under this flow condition, there is a strong upstream running shock. The strength and position of this shock are very sensitive to blade geometry variations. For a fan where all the blades are identical, the primary tone observed upstream of the fan will be the blade passing frequency. If there are small variations in geometry between blades, then tones below the blade passing frequency arise MPTs. Stagger angle differences as small as 0.1 can give rise to significant MPT. It is also noted that MPT noise is more pronounced when the fan is operating in an unstarted mode. Computational results using a three-dimensional flow solver to compute the complete annulus flow with non-uniform fans indicate that MPT noise can be estimated in a relatively simple way. Hence, once the effect of a typical geometry variation of one blade in an otherwise uniform blade row is known, the effect of all the blades being different can be quickly computed via superposition. Two computer programs that were developed as part of this work are used in conjunction with a user s computational fluid dynamics (CFD) code to predict MPT spectra for a fan with a specified set of geometric variations: (1) The first program ROTBLD reads the users CFD solution files for a single blade passage via an API (Application Program Interface). There are options to replicate and perturb the geometry with typical variations stagger, camber, thickness, and pitch. The multi-passage CFD solution files are then written in the user s file format using the API. (2) The second program SUPERPOSE requires two input files: the first is the circumferential upstream pressure distribution extracted from the CFD solution on the multi-passage mesh

  7. Perceived Noise Analysis for Offset Jets Applied to Commercial Supersonic Aircraft

    Science.gov (United States)

    Huff, Dennis L.; Henderson, Brenda S.; Berton, Jeffrey J.; Seidel, Jonathan A.

    2016-01-01

    A systems analysis was performed with experimental jet noise data, engine/aircraft performance codes and aircraft noise prediction codes to assess takeoff noise levels and mission range for conceptual supersonic commercial aircraft. A parametric study was done to identify viable engine cycles that meet NASA's N+2 goals for noise and performance. Model scale data from offset jets were used as input to the aircraft noise prediction code to determine the expected sound levels for the lateral certification point where jet noise dominates over all other noise sources. The noise predictions were used to determine the optimal orientation of the offset nozzles to minimize the noise at the lateral microphone location. An alternative takeoff procedure called "programmed lapse rate" was evaluated for noise reduction benefits. Results show there are two types of engines that provide acceptable mission range performance; one is a conventional mixed-flow turbofan and the other is a three-stream variable-cycle engine. Separate flow offset nozzles reduce the noise directed toward the thicker side of the outer flow stream, but have less benefit as the core nozzle pressure ratio is reduced. At the systems level for a three-engine N+2 aircraft with full throttle takeoff, there is a 1.4 EPNdB margin to Chapter 3 noise regulations predicted for the lateral certification point (assuming jet noise dominates). With a 10% reduction in thrust just after clearing the runway, the margin increases to 5.5 EPNdB. Margins to Chapter 4 and Chapter 14 levels will depend on the cumulative split between the three certification points, but it appears that low specific thrust engines with a 10% reduction in thrust (programmed lapse rate) can come close to meeting Chapter 14 noise levels. Further noise reduction is possible with engine oversizing and derated takeoff, but more detailed mission studies are needed to investigate the range impacts as well as the practical limits for safety and takeoff

  8. Progress of Aircraft System Noise Assessment with Uncertainty Quantification for the Environmentally Responsible Aviation Project

    Science.gov (United States)

    Thomas, Russell H.; Burley, Casey L.; Guo, Yueping

    2016-01-01

    Aircraft system noise predictions have been performed for NASA modeled hybrid wing body aircraft advanced concepts with 2025 entry-into-service technology assumptions. The system noise predictions developed over a period from 2009 to 2016 as a result of improved modeling of the aircraft concepts, design changes, technology development, flight path modeling, and the use of extensive integrated system level experimental data. In addition, the system noise prediction models and process have been improved in many ways. An additional process is developed here for quantifying the uncertainty with a 95% confidence level. This uncertainty applies only to the aircraft system noise prediction process. For three points in time during this period, the vehicle designs, technologies, and noise prediction process are documented. For each of the three predictions, and with the information available at each of those points in time, the uncertainty is quantified using the direct Monte Carlo method with 10,000 simulations. For the prediction of cumulative noise of an advanced aircraft at the conceptual level of design, the total uncertainty band has been reduced from 12.2 to 9.6 EPNL dB. A value of 3.6 EPNL dB is proposed as the lower limit of uncertainty possible for the cumulative system noise prediction of an advanced aircraft concept.

  9. Effects of changed aircraft noise exposure on experiential qualities of outdoor recreational areas.

    Science.gov (United States)

    Krog, Norun Hjertager; Engdahl, Bo; Tambs, Kristian

    2010-10-01

    The literature indicates that sound and visual stimuli interact in the impression of landscapes. This paper examines the relationship between annoyance with sound from aircraft and annoyance with other area problems (e.g., careless bicycle riding, crowding, etc.), and how changes in noise exposure influence the perceived overall recreational quality of outdoor recreational areas. A panel study (telephone interviews) conducted before and after the relocation of Norway's main airport in 1998 examined effects of decreased or increased noise exposure in nearby recreational areas (n = 591/455). Sound from aircraft annoyed the largest proportion of recreationists, except near the old airport after the change. The decrease in annoyance with sound from aircraft was accompanied by significant decreases in annoyance with most of the other area problems. Near the new airport annoyance with most factors beside sound from aircraft increased slightly, but not significantly. A relationship between aircraft noise annoyance and perceived overall recreational quality of the areas was found. PMID:21139858

  10. Practical ranges of loudness levels of various types of environmental noise, including traffic noise, aircraft noise, and industrial noise

    NARCIS (Netherlands)

    Salomons, E.M.; Janssen, S.A.

    2011-01-01

    In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a noi

  11. Real-Time Noise Prediction of V/STOL Aircraft in Maneuvering Flight Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal outlines a plan for enhancing and integrating new breakthrough technologies to provide accurate real-time noise prediction of V/STOL aircraft in...

  12. High Sensitivity Pulsed Laser Vibrometer for Aircraft Interior Noise Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an innovative pulsed laser vibrometer technology for the monitoring of interior noise inside an aircraft. The optical speckle-tolerant nature of the...

  13. Auralization of NASA N+2 Aircraft Concepts from System Noise Predictions

    Science.gov (United States)

    Rizzi, Stephen A.; Burley, Casey L.; Thomas, Russel H.

    2016-01-01

    Auralization of aircraft flyover noise provides an auditory experience that complements integrated metrics obtained from system noise predictions. Recent efforts have focused on auralization methods development, specifically the process by which source noise information obtained from semi-empirical models, computational aeroacoustic analyses, and wind tunnel and flight test data, are used for simulated flyover noise at a receiver on the ground. The primary focus of this work, however, is to develop full vehicle auralizations in order to explore the distinguishing features of NASA's N+2 aircraft vis-à-vis current fleet reference vehicles for single-aisle and large twin-aisle classes. Some features can be seen in metric time histories associated with aircraft noise certification, e.g., tone-corrected perceived noise level used in the calculation of effective perceived noise level. Other features can be observed in sound quality metrics, e.g., loudness, sharpness, roughness, fluctuation strength and tone-to-noise ratio. A psychoacoustic annoyance model is employed to establish the relationship between sound quality metrics and noise certification metrics. Finally, the auralizations will serve as the basis for a separate psychoacoustic study aimed at assessing how well aircraft noise certification metrics predict human annoyance for these advanced vehicle concepts.

  14. On Physical Aeroacoustics with Some Implications for Low-Noise Aircraft Design and Airport Operations

    OpenAIRE

    Luís M. B. C. Campos

    2015-01-01

    Air traffic is growing at a steady rate of 3% to 5% per year in most regions of the world, implying a doubling every 15–25 years. This requires major advances in aircraft noise reduction at airports, just not to increase the noise exposure due to the larger number of aircraft movements. In fact it can be expected, as a consequence of increased opposition to noise by near airport residents, that the overall noise exposure will have to be reduced, by bans, curfews, fines, and other means and li...

  15. Practical Ranges of Loudness Levels of Various Types of Environmental Noise, Including Traffic Noise, Aircraft Noise, and Industrial Noise

    OpenAIRE

    Sabine A. Janssen; Salomons, Erik M.

    2011-01-01

    In environmental noise control one commonly employs the A-weighted sound level as an approximate measure of the effect of noise on people. A measure that is more closely related to direct human perception of noise is the loudness level. At constant A-weighted sound level, the loudness level of a noise signal varies considerably with the shape of the frequency spectrum of the noise signal. In particular the bandwidth of the spectrum has a large effect on the loudness level, due to the effect o...

  16. Effects of Changed Aircraft Noise Exposure on the Use of Outdoor Recreational Areas

    OpenAIRE

    Norun Hjertager Krog; Kristian Tambs; Bo Engdahl

    2010-01-01

    This paper examines behavioural responses to changes in aircraft noise exposure in local outdoor recreational areas near airports. Results from a panel study conducted in conjunction with the relocation of Norway’s main airport in 1998 are presented. One recreational area was studied at each airport site. The samples (n = 1,264/1,370) were telephone interviewed about their use of the area before and after the change. Results indicate that changed aircraft noise exposure may influence individu...

  17. Determination and Applications of Environmental Costs at Different Sized Airports – Aircraft Noise and Engine Emissions.

    OpenAIRE

    Lu, Cherie; Morrell, Peter

    2006-01-01

    With the increasing trend of charging for externalities and the aim of encouraging the sustainable development of the air transport industry, there is a need to evaluate the social costs of these undesirable side effects, mainly aircraft noise and engine emissions, for different airports. The aircraft noise and engine emissions social costs are calculated in monetary terms for five different sized airports, ranging from hub airports to small regional airports. The number of residences within ...

  18. Multilevel modelling of aircraft noise on performance tests in schools around Heathrow Airport London

    OpenAIRE

    Haines, M; Stansfeld, S; Head, J.; Job, R

    2002-01-01

    Design: This is a cross sectional study using the National Standardised Scores (SATs) in mathematics, science, and English (11 000 scores from children aged 11 years). The analyses used multilevel modelling to determine the effects of chronic aircraft noise exposure on childrens' school performance adjusting for demographic, socioeconomic and school factors in 123 primary schools around Heathrow Airport. Schools were assigned aircraft noise exposure level from the 1994 Civil Aviation Authorit...

  19. Increased prevalence of hypertension in a population exposed to aircraft noise

    OpenAIRE

    Rosenlund, M.; Berglind, N; Pershagen, G.; Jarup, L.; Bluhm, G

    2001-01-01

    OBJECTIVES—To investigate whether there is a relation between residential exposure to aircraft noise and hypertension.
METHODS—The study population comprised two random samples of subjects aged 19-80 years, one including 266 residents in the vicinity of Stockholm Arlanda airport, and another comprising 2693 inhabitants in other parts of Stockholm county. The subjects were classified according to the time weighted equal energy and maximum aircraft noise levels at their residence. A questionnai...

  20. Health effects of aircraft noise near three French airports: results from pilot epidemiological study of the DEBATS study.

    OpenAIRE

    Evrard, Anne-Sophie; Khati , Inès; Champelovier, Patricia; Lambert, Jacques; Laumon, Bernard

    2014-01-01

    While many surveys carried out both in France and abroad address aircraft noise annoyance or report adverse effects on sleep quality, much fewer consider at the same time the physiological effects of this noise exposure. The largest study to date, the HYENA study, has evidenced an association between aircraft noise exposure and hypertension. DEBATS is a research program (2011-2018) aiming to characterize the relations between aircraft noise exposure and the health status of the French populat...

  1. Combined Effect of Aircraft Noise and Pollutant Emissions by using ANN Model to Determine Healthy Risk Level

    OpenAIRE

    SETIA KURNIAWAN, Jermanto; KATILI, Irwan; MOERSIDIK, Setyo Sarwanto; Khardi, Salah

    2013-01-01

    Aircraft noise and pollutant emissions are an important part of the sources of pollution around airport that directly or indirectly will affect harmful to human health and ecosystems. The effects of aircraft noise and emissions on the populations around airport are deal with annoying and sometimes dangerous. In order to address this issue, the research propose an integrating model of aircraft noise and pollutant emissions by combining effects of both noise and pollutant emissions using Artifi...

  2. Aircraft Engine Noise Research and Testing at the NASA Glenn Research Center

    Science.gov (United States)

    Elliott, Dave

    2015-01-01

    The presentation will begin with a brief introduction to the NASA Glenn Research Center as well as an overview of how aircraft engine noise research fits within the organization. Some of the NASA programs and projects with noise content will be covered along with the associated goals of aircraft noise reduction. Topics covered within the noise research being presented will include noise prediction versus experimental results, along with engine fan, jet, and core noise. Details of the acoustic research conducted at NASA Glenn will include the test facilities available, recent test hardware, and data acquisition and analysis methods. Lastly some of the actual noise reduction methods investigated along with their results will be shown.

  3. Aircraft Engine Exhaust Nozzle System for Jet Noise Reduction

    Science.gov (United States)

    Thomas, Russell H. (Inventor); Czech, Michael J. (Inventor); Elkoby, Ronen (Inventor)

    2014-01-01

    The aircraft exhaust engine nozzle system includes a fan nozzle to receive a fan flow from a fan disposed adjacent to an engine disposed above an airframe surface of the aircraft, a core nozzle disposed within the fan nozzle and receiving an engine core flow, and a pylon structure connected to the core nozzle and structurally attached with the airframe surface to secure the engine to the aircraft.

  4. Adaptive Noise Cancellation System for Low Frequency Transmission of Sound in Open Fan Aircraft

    Directory of Open Access Journals (Sweden)

    Steven Griffin

    2013-01-01

    Full Text Available This paper describes the use of a structural/acoustic model of a section of a large aircraft to help define the sensor/actuator architecture that was used in a hardware demonstration of adaptive noise cancellation. Disturbances considered were representative of propeller-induced disturbances from an open fan aircraft. Controller on and controller off results from a hardware demonstration on a portion of a large aircraft are also included. The use of the model has facilitated the development of a new testing technique, closely related to modal testing, that can be used to find good structural actuator locations for adaptive noise cancellation.

  5. Hybrid Wing Body Aircraft System Noise Assessment with Propulsion Airframe Aeroacoustic Experiments

    Science.gov (United States)

    Thomas, Russell H.; Burley, Casey L.; Olson, Erik D.

    2010-01-01

    A system noise assessment of a hybrid wing body configuration was performed using NASA s best available aircraft models, engine model, and system noise assessment method. A propulsion airframe aeroacoustic effects experimental database for key noise sources and interaction effects was used to provide data directly in the noise assessment where prediction methods are inadequate. NASA engine and aircraft system models were created to define the hybrid wing body aircraft concept as a twin engine aircraft with a 7500 nautical mile mission. The engines were modeled as existing technology high bypass ratio turbofans. The baseline hybrid wing body aircraft was assessed at 22 dB cumulative below the FAA Stage 4 certification level. To determine the potential for noise reduction with relatively near term technologies, seven other configurations were assessed beginning with moving the engines two fan nozzle diameters upstream of the trailing edge and then adding technologies for reduction of the highest noise sources. Aft radiated noise was expected to be the most challenging to reduce and, therefore, the experimental database focused on jet nozzle and pylon configurations that could reduce jet noise through a combination of source reduction and shielding effectiveness. The best configuration for reduction of jet noise used state-of-the-art technology chevrons with a pylon above the engine in the crown position. This configuration resulted in jet source noise reduction, favorable azimuthal directivity, and noise source relocation upstream where it is more effectively shielded by the limited airframe surface, and additional fan noise attenuation from acoustic liner on the crown pylon internal surfaces. Vertical and elevon surfaces were also assessed to add shielding area. The elevon deflection above the trailing edge showed some small additional noise reduction whereas vertical surfaces resulted in a slight noise increase. With the effects of the configurations from the

  6. Integration of noise control into the product design process : a case study : the Silent Aircraft Initiative

    Energy Technology Data Exchange (ETDEWEB)

    Faszer, A. [Noise Solutions Inc., Calgary, AB (Canada)

    2007-07-01

    The Silent Aircraft Initiative (SAI) is a study being conducted by the Cambridge-MIT Institute to discover ways to significantly reduce aircraft noise. Part of the study focuses on developing aircraft and engine designs that meet the SAI objectives. This presentation included several illustrations of the favoured configuration of a blended wing design, with 4 engines located on the upper surface of a shallow wing which shields engine noise. This presentation described various engine parts such as the low specific thrust turbofan, the variable area nozzle and the acoustic treatment in the intake and exhaust turbomachinery that minimizes noise. The requirements for market viability of the aircraft were discussed as well as the technical challenges in terms of its propulsion systems; structural analysis; mechanical design; low speed aerodynamic performance; cabin layout; and maintenance considerations. It was concluded that the SAI has achieved a credible conceptual aircraft design given the high risk of the technologies used. The project has met objectives of a functionally silent and fuel efficient aircraft. The new conceptual aircraft has potential for fuel burn of 149 pax-miles per imperial gallon and noise of 63 dBA near the perimeter of airports. 1 tab., 48 figs.

  7. Auxiliary power unit noise of Boeing B737 and B747 aircraft

    Science.gov (United States)

    Kwan, Jimmy S. W.; Yang, S. J. Eric

    Most modern civil aircraft have an Auxiliary Power Unit (APU) which provides compressed air for engine starting and the air-conditioning system on ground and electrical power for aircraft use both on-ground and in-fligth. It is basically a gas turbine engine and it consists of a compressor section, a turbine section, and an accessory drive section. For Boeing B737 and B747 aircraft, the APU is located inside a compartment in the tail section of the aircraft and is completely enclosed by a sound-reduction fire-proof titanium shroud. APU noise is one of the major noise sources at many airports and is extremely important for a densely populated city such as Hong Kong. The noise from APU can affect many people, including ground crew aircraft maintenance staff, and people living in the vicinity of the airport. However, there is very little information available in the literature about APU noise. This paper describes the noise measurement method and presents the measurement results for APUs of one B747 and two B737 aircraft under both 'loaded' and 'no-load' conditions.

  8. Testing a theory of aircraft noise annoyance: A structural equation analysis

    NARCIS (Netherlands)

    Kroesen, M.; Molin, E.J.E.; Van Wee, B.

    2008-01-01

    Previous research has stressed the relevance of nonacoustical factors in the perception of aircraft noise. However, it is largely empirically driven and lacks a sound theoretical basis. In this paper, a theoretical model which explains noise annoyance based on the psychological stress theory is empi

  9. Aircraft noise exposure affects rat behavior, plasma norepinephrine levels, and cell morphology of the temporal lobe

    Institute of Scientific and Technical Information of China (English)

    Guo-qing DI; Bing ZHOU; Zheng-guang; LI, Qi-li LIN

    2011-01-01

    In order to investigate the physiological effects of airport noise exposure on organisms,in this study,we exposed Sprague-Dawley rats in soundproof chambers to previously recorded aircraft-related noise for 65 d.For comparison,we also used unexposed control rats.Noise was arranged according to aircraft flight schedules and was adjusted to its weighted equivalent continuous perceived noise levels (LwEcPN) of 75 and 80 dB for the two experimental groups.We examined rat behaviors through an open field test and measured the concentrations of plasma norepinephrine (NE) by high performance liquid chromatography-fluorimetric detection (HPLC-FLD).We also examined the morphologies of neurons and synapses in the temporal lobe by transmission electron microscopy (TEM).Our results showed that rats exposed to airport noise of 80 dB had significantly lower line crossing number (P<0.05) and significantly longer center area duration (P<0.05) than control animals.After 29 d of airport noise exposure,the concentration of plasma NE of exposed rats was significantly higher than that of the control group (P<0.05).We also determined that the neuron and synapsis of the temporal lobe of rats showed signs of damage after aircraft noise of 80 dB exposure for 65 d.In conclusion,exposing rats to long-term aircraft noise affects their behaviors,plasma NE levels,and cell morphology of the temporal lobe.

  10. Design of the Next Generation Aircraft Noise Prediction Program: ANOPP2

    Science.gov (United States)

    Lopes, Leonard V., Dr.; Burley, Casey L.

    2011-01-01

    The requirements, constraints, and design of NASA's next generation Aircraft NOise Prediction Program (ANOPP2) are introduced. Similar to its predecessor (ANOPP), ANOPP2 provides the U.S. Government with an independent aircraft system noise prediction capability that can be used as a stand-alone program or within larger trade studies that include performance, emissions, and fuel burn. The ANOPP2 framework is designed to facilitate the combination of acoustic approaches of varying fidelity for the analysis of noise from conventional and unconventional aircraft. ANOPP2 integrates noise prediction and propagation methods, including those found in ANOPP, into a unified system that is compatible for use within general aircraft analysis software. The design of the system is described in terms of its functionality and capability to perform predictions accounting for distributed sources, installation effects, and propagation through a non-uniform atmosphere including refraction and the influence of terrain. The philosophy of mixed fidelity noise prediction through the use of nested Ffowcs Williams and Hawkings surfaces is presented and specific issues associated with its implementation are identified. Demonstrations for a conventional twin-aisle and an unconventional hybrid wing body aircraft configuration are presented to show the feasibility and capabilities of the system. Isolated model-scale jet noise predictions are also presented using high-fidelity and reduced order models, further demonstrating ANOPP2's ability to provide predictions for model-scale test configurations.

  11. Policy discourse and people's internal frames, and declared aircraft noise annoyance: an application of Q-methodology

    NARCIS (Netherlands)

    M. Kroesen; C. Bröer

    2009-01-01

    Aircraft noise annoyance is studied extensively, but often without an explicit theoretical framework. In this article, a social approach for noise annoyance is proposed. The idea that aircraft noise is meaningful to people within a socially produced discourse is assumed and tested. More particularly

  12. Policy discourse, people’s internal frames, and declared aircraft noise annoyance: An application of Q-methodology

    NARCIS (Netherlands)

    Kroesen, M.; Bröer, C.

    2009-01-01

    Aircraft noise annoyance is studied extensively, but often without an explicit theoretical framework. In this article, a social approach for noise annoyance is proposed. The idea that aircraft noise is meaningful to people within a socially produced discourse is assumed and tested. More particularly

  13. Aircraft noise in Berlin affects quality of life even outside the airport grounds

    OpenAIRE

    Eibich, Peter; Kholodilin, Konstantin; Krekel, Christian; Wagner, Gert G.

    2015-01-01

    Aircraft noise is a particularly problematic source of noise as many airports are located in or near major cities and, as a result, densely populated areas are affected. Data from the Berlin Aging Study II (Berliner Altersstudie II, BASE-II), whose socio-economic module is based on the longitudinal Socio-Economic Panel (SOEP) study which has been conducted since 1984, allows us to examine the effect of different levels of aircraft noise on the subjective wellbeing and health of the older resi...

  14. A review and update of the NASA aircraft noise prediction program propeller analysis system

    Science.gov (United States)

    Golub, Robert A.; Nguyen, L. Cathy

    1989-04-01

    The National Aeronautics and Space Administration (NASA) Aircraft Noise Prediction Program (ANOPP) Propeller Analysis System (PAS) is a set of computational modules for predicting the aerodynamics, performance, and noise of propellers. The ANOPP PAS has the capability to predict noise levels for propeller aircraft certification and produce parametric scaling laws for the adjustment of measured data to reference conditions. A technical overview of the prediction techniques incorporated into the system is presented. The prediction system has been applied to predict the noise signature of a variety of propeller configurations including the effects of propeller angle of attack. A summary of these validation studies is discussed with emphasis being placed on the wind tunnel and flight test programs sponsored by the Federal Aviation Administration (FAA) for the Piper Cherokee Lance aircraft. A number of modifications and improvements have been made to the system and both DEC VAX and IBM-PC versions of the system have been added to the original CDC NOS version.

  15. Noise Annoyance Is Associated with Depression and Anxiety in the General Population- The Contribution of Aircraft Noise

    Science.gov (United States)

    Beutel, Manfred E.; Jünger, Claus; Klein, Eva M.; Wild, Philipp; Lackner, Karl; Blettner, Maria; Binder, Harald; Michal, Matthias; Wiltink, Jörg; Brähler, Elmar; Münzel, Thomas

    2016-01-01

    Background While noise annoyance has become recognized as an important environmental stressor, its association to mental health has hardly been studied. We therefore determined the association of noise annoyance to anxiety and depression and explored the contribution of diverse environmental sources to overall noise annoyance. Patients and Methods We investigated cross-sectional data of n = 15.010 participants of the Gutenberg Health Study (GHS), a population-based, prospective, single-center cohort study in Mid-Germany (age 35 to 74 years). Noise annoyance was assessed separately for road traffic, aircraft, railways, industrial, neighborhood indoor and outdoor noise (“during the day”; “in your sleep”) on 5-point scales (“not at all” to “extremely”); depression and anxiety were assessed by the PHQ-9, resp. GAD-2. Results Depression and anxiety increased with the degree of overall noise annoyance. Compared to no annoyance, prevalence ratios for depression, respectively anxiety increased from moderate (PR depression 1.20; 95%CI 1.00 to 1.45; PR anxiety 1.42; 95% CI 1.15 to 1.74) to extreme annoyance (PR depression 1.97; 95%CI 1.62 to 2.39; PR anxiety 2.14; 95% CI 1.71 to 2.67). Compared to other sources, aircraft noise annoyance was prominent affecting almost 60% of the population. Interpretation Strong noise annoyance was associated with a two-fold higher prevalence of depression and anxiety in the general population. While we could not relate annoyance due to aircraft noise directly to depression and anxiety, we established that it was the major source of annoyance in the sample, exceeding the other sources in those strongly annoyed. Prospective follow-up data will address the issue of causal relationships between annoyance and mental health. PMID:27195894

  16. Noise Annoyance Is Associated with Depression and Anxiety in the General Population- The Contribution of Aircraft Noise.

    Directory of Open Access Journals (Sweden)

    Manfred E Beutel

    Full Text Available While noise annoyance has become recognized as an important environmental stressor, its association to mental health has hardly been studied. We therefore determined the association of noise annoyance to anxiety and depression and explored the contribution of diverse environmental sources to overall noise annoyance.We investigated cross-sectional data of n = 15.010 participants of the Gutenberg Health Study (GHS, a population-based, prospective, single-center cohort study in Mid-Germany (age 35 to 74 years. Noise annoyance was assessed separately for road traffic, aircraft, railways, industrial, neighborhood indoor and outdoor noise ("during the day"; "in your sleep" on 5-point scales ("not at all" to "extremely"; depression and anxiety were assessed by the PHQ-9, resp. GAD-2.Depression and anxiety increased with the degree of overall noise annoyance. Compared to no annoyance, prevalence ratios for depression, respectively anxiety increased from moderate (PR depression 1.20; 95%CI 1.00 to 1.45; PR anxiety 1.42; 95% CI 1.15 to 1.74 to extreme annoyance (PR depression 1.97; 95%CI 1.62 to 2.39; PR anxiety 2.14; 95% CI 1.71 to 2.67. Compared to other sources, aircraft noise annoyance was prominent affecting almost 60% of the population.Strong noise annoyance was associated with a two-fold higher prevalence of depression and anxiety in the general population. While we could not relate annoyance due to aircraft noise directly to depression and anxiety, we established that it was the major source of annoyance in the sample, exceeding the other sources in those strongly annoyed. Prospective follow-up data will address the issue of causal relationships between annoyance and mental health.

  17. Hybrid Prediction Method for Aircraft Interior Noise Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the project is research and development of methods for application of the Hybrid FE-SEA method to aircraft vibro-acoustic problems. This proposal...

  18. Hybrid Prediction Method for Aircraft Interior Noise Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal discusses the development and application of new methods of structural-acoustic analysis in order to address existing problems in aircraft interior...

  19. Advanced Acoustic Blankets for Improved Aircraft Interior Noise Reduction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the proposed Phase II research effort is to develop heterogeneous (HG) blankets for improved sound reduction in aircraft structures. Phase I...

  20. Annoyance and acceptability judgements of noise produced by three types of aircraft by residents living near JFK Airport

    Science.gov (United States)

    Borsky, P. N.

    1974-01-01

    A random sample of selected communities near JFK Airport were interviewed. Subsamples, with differing feelings of fear of aircraft crashes and different locations of residence were invited to participate in a laboratory experiment. The subjects were exposed to tape recordings of simulated flyovers of aircraft in approach and departure operations at nominal distances from the airport. The subjects judged the extent of noise annoyance and acceptability of the aircraft noises. Results indicate that level of noise is most significant in affecting annoyance judgements. Subjects with feelings of high fear report significantly more annoyance and less acceptability of aircraft noise than subjects with feelings of low fear.

  1. Perceived Noise Analysis for Offset Jets Applied to Commercial Supersonic Aircraft

    Science.gov (United States)

    Huff, Dennis L.; Henderson, Brenda S.; Berton, Jeffrey J.; Seidel, Jonathan A.

    2016-01-01

    A systems analysis was performed with experimental jet noise data, engine/aircraft performance codes and aircraft noise prediction codes to assess takeoff noise levels and mission range for conceptual supersonic commercial aircraft. A parametric study was done to identify viable engine cycles that meet NASAs N+2 goals for noise and performance. Model scale data from offset jets was used as input to the aircraft noise prediction code to determine the expected sound levels for the lateral certification point where jet noise dominates over all other noise sources. The noise predictions were used to determine the optimal orientation of the offset nozzles to minimize the noise at the lateral microphone location. An alternative takeoff procedure called programmed lapse rate was evaluated for noise reduction benefits. Results show there are two types of engines that provide acceptable range performance; one is a standard mixed-flow turbofan with a single-stage fan, and the other is a three-stream variable-cycle engine with a multi-stage fan. The engine with a single-stage fan has a lower specific thrust and is 8 to 10 EPNdB quieter for takeoff. Offset nozzles reduce the noise directed toward the thicker side of the outer flow stream, but have less benefit as the core nozzle pressure ratio is reduced and the bypass-to-core area ratio increases. At the systems level for a three-engine N+2 aircraft with full throttle takeoff, there is a 1.4 EPNdB margin to Chapter 3 noise regulations predicted for the lateral certification point (assuming jet noise dominates). With a 10 reduction in thrust just after takeoff rotation, the margin increases to 5.5 EPNdB. Margins to Chapter 4 and Chapter 14 levels will depend on the cumulative split between the three certification points, but it appears that low specific thrust engines with a 10 reduction in thrust (programmed lapse rate) can come close to meeting Chapter 14 noise levels. Further noise reduction is possible with additional

  2. A Process for Assessing NASA's Capability in Aircraft Noise Prediction Technology

    Science.gov (United States)

    Dahl, Milo D.

    2008-01-01

    An acoustic assessment is being conducted by NASA that has been designed to assess the current state of the art in NASA s capability to predict aircraft related noise and to establish baselines for gauging future progress in the field. The process for determining NASA s current capabilities includes quantifying the differences between noise predictions and measurements of noise from experimental tests. The computed noise predictions are being obtained from semi-empirical, analytical, statistical, and numerical codes. In addition, errors and uncertainties are being identified and quantified both in the predictions and in the measured data to further enhance the credibility of the assessment. The content of this paper contains preliminary results, since the assessment project has not been fully completed, based on the contributions of many researchers and shows a select sample of the types of results obtained regarding the prediction of aircraft noise at both the system and component levels. The system level results are for engines and aircraft. The component level results are for fan broadband noise, for jet noise from a variety of nozzles, and for airframe noise from flaps and landing gear parts. There are also sample results for sound attenuation in lined ducts with flow and the behavior of acoustic lining in ducts.

  3. Review of the effect of aircraft noise on sleep disturbance in adults.

    Science.gov (United States)

    Perron, Stéphane; Tétreault, Louis-François; King, Norman; Plante, Céline; Smargiassi, Audrey

    2012-01-01

    Noise exposure generated by air traffic has been linked with sleep disturbances. The purpose of this systematic review is to clarify whether there is a causal link between aircraft noise exposure and sleep disturbances. Only complete, peer-reviewed articles published in scientific journals were examined. Papers published until December 2010 were considered. To be included, articles had to focus on subjects aged 18 or over and include an objective evaluation of noise levels. Studies were classified according to quality. Given the paucity of studies with comparable outcome measures, we performed a narrative synthesis using a best-evidence synthesis approach. The primary study findings were tabulated. Similarities and differences between studies were investigated. Of the 12 studies surveyed that dealt with sleep disturbances, four were considered to be of high quality, five were considered to be of moderate quality and three were considered to be of low quality. All moderate- to high-quality studies showed a link between aircraft noise events and sleep disturbances such as awakenings, decreased slow wave sleep time or the use of sleep medication. This review suggests that there is a causal relation between exposure to aircraft noise and sleep disturbances. However, the evidence comes mostly from experimental studies focusing on healthy adults. Further studies are necessary to determine the impact of aircraft noise on sleep disturbance for individuals more than 65 years old and for those with chronic diseases. PMID:22517305

  4. Review of the effect of aircraft noise on sleep disturbance in adults

    Directory of Open Access Journals (Sweden)

    Stéphane Perron

    2012-01-01

    Full Text Available Noise exposure generated by air traffic has been linked with sleep disturbances. The purpose of this systematic review is to clarify whether there is a causal link between aircraft noise exposure and sleep disturbances. Only complete, peer-reviewed articles published in scientific journals were examined. Papers published until December 2010 were considered. To be included, articles had to focus on subjects aged 18 or over and include an objective evaluation of noise levels. Studies were classified according to quality. Given the paucity of studies with comparable outcome measures, we performed a narrative synthesis using a best-evidence synthesis approach. The primary study findings were tabulated. Similarities and differences between studies were investigated. Of the 12 studies surveyed that dealt with sleep disturbances, four were considered to be of high quality, five were considered to be of moderate quality and three were considered to be of low quality. All moderate- to high-quality studies showed a link between aircraft noise events and sleep disturbances such as awakenings, decreased slow wave sleep time or the use of sleep medication. This review suggests that there is a causal relation between exposure to aircraft noise and sleep disturbances. However, the evidence comes mostly from experimental studies focusing on healthy adults. Further studies are necessary to determine the impact of aircraft noise on sleep disturbance for individuals more than 65 years old and for those with chronic diseases.

  5. Reduction of JT8D powered aircraft noise by engine refanning

    Science.gov (United States)

    Stitt, L. E.; Medeiros, A. A.

    1974-01-01

    The purpose of the Refan Program is to establish the technical feasibility of substantially reducing the noise levels of existing JT8D powered aircraft. This would be accomplished by retrofitting the existing fleet with quieter refan engines and new acoustically treated nacelles. No major technical problems exist that preclude the development and installation of refanned engines on aircraft currently powered by the JT8D engine. The refan concept is technically feasible and provides calculated noise reductions of from 7 to 8 EPNdB for the B727-200 aircraft and from 10 to 12 EPNdB for the DC-9-32 aircraft at the FAR Part 36 measuring stations. Corresponding reductions in the 90 EPNdB footprint area are estimated to vary from about 70 percent for the DC-9 to about 80 percent for the B727.

  6. Two-Aircraft Dynamic System on Approach. Flight Path and noise Optimization

    OpenAIRE

    Nahayo, F.; Khardi, S.; Haddou, M.

    2012-01-01

    The aim of this paper is to present and to solve a mathematical model of two-aircraft optimal control problem reducing noise during the approach. This is a non-convex optimal control problem governed by ordinary non-linear differential equations. A Symplectic Partitioned Runge-Kutta discretization and the Pontryaguin maximum principle are used. Discretization scheme provides a sufficiently high order requiring a computation of the partial derivatives of the aircraft dynamic parameters. The no...

  7. The Factors affecting pollution and noise social costs of the current Aircraft fleet: an econometric analysis

    OpenAIRE

    Grampella, M; Martini, G.; Scotti, D.; Zambon, G.

    2014-01-01

    In the last years, environmental issues have become increasingly relevant in the air transport industry. This exerts an influence on airline fleet choice as demonstrated by the fact that some carriers have begun to purchase more environmentally friendly aircrafts or to include environmental objectives into performance evaluation. This paper aims at analyzing the worldwide fleet by comparing the about 1400 existing (at year 2010) combinations of aircraft/engine models in terms of (1) noise...

  8. Role of structural noise in aircraft pressure cockpit from vibration action of new-generation engines

    Science.gov (United States)

    Baklanov, V. S.

    2016-07-01

    The evolution of new-generation aircraft engines is transitioning from a bypass ratio of 4-6 to an increased ratio of 8-12. This is leading to substantial broadening of the vibration spectrum of engines with a shift to the low-frequency range due to decreased rotation speed of the fan rotor, in turn requiring new solutions to decrease structural noise from engine vibrations to ensure comfort in the cockpits and cabins of aircraft.

  9. Simulation-Based Airframe Noise Prediction of a Full-Scale, Full Aircraft

    Science.gov (United States)

    Khorrami, Mehdi R.; Fares, Ehab

    2016-01-01

    A previously validated computational approach applied to an 18%-scale, semi-span Gulfstream aircraft model was extended to the full-scale, full-span aircraft in the present investigation. The full-scale flap and main landing gear geometries used in the simulations are nearly identical to those flown on the actual aircraft. The lattice Boltzmann solver PowerFLOW® was used to perform time-accurate predictions of the flow field associated with this aircraft. The simulations were performed at a Mach number of 0.2 with the flap deflected 39 deg. and main landing gear deployed (landing configuration). Special attention was paid to the accurate prediction of major sources of flap tip and main landing gear noise. Computed farfield noise spectra for three selected baseline configurations (flap deflected 39 deg. with and without main gear extended, and flap deflected 0 deg. with gear deployed) are presented. The flap brackets are shown to be important contributors to the farfield noise spectra in the mid- to high-frequency range. Simulated farfield noise spectra for the baseline configurations, obtained using a Ffowcs Williams and Hawkings acoustic analogy approach, were found to be in close agreement with acoustic measurements acquired during the 2006 NASA-Gulfstream joint flight test of the same aircraft.

  10. Toward Reduced Aircraft Community Noise Impact Via a Perception-Influenced Design Approach

    Science.gov (United States)

    Rizzi, Stephen A.

    2016-01-01

    This is an exciting time for aircraft design. New configurations, including small multi-rotor uncrewed aerial systems, fixed- and tilt-wing distributed electric propulsion aircraft, high-speed rotorcraft, hybrid-electric commercial transports, and low-boom supersonic transports, are being made possible through a host of propulsion and airframe technology developments. The resulting noise signatures may be radically different, both spectrally and temporally, than those of the current fleet. Noise certification metrics currently used in aircraft design do not necessarily reflect these characteristics and therefore may not correlate well with human response. Further, as operations and missions become less airport-centric, e.g., those associated with on-demand mobility or package delivery, vehicles may operate in closer proximity to the population than ever before. Fortunately, a new set of tools are available for assessing human perception during the design process in order to affect the final design in a positive manner. The tool chain utilizes system noise prediction methods coupled with auralization and psychoacoustic testing, making possible the inclusion of human response to noise, along with performance criteria and certification requirements, into the aircraft design process. Several case studies are considered to illustrate how this approach could be used to influence the design of future aircraft.

  11. Aircraft noise exposure affects rat behavior, plasma norepinephrine levels, and cell morphology of the temporal lobe.

    Science.gov (United States)

    Di, Guo-Qing; Zhou, Bing; Li, Zheng-Guang; Lin, Qi-Li

    2011-12-01

    In order to investigate the physiological effects of airport noise exposure on organisms, in this study, we exposed Sprague-Dawley rats in soundproof chambers to previously recorded aircraft-related noise for 65 d. For comparison, we also used unexposed control rats. Noise was arranged according to aircraft flight schedules and was adjusted to its weighted equivalent continuous perceived noise levels (L(WECPN)) of 75 and 80 dB for the two experimental groups. We examined rat behaviors through an open field test and measured the concentrations of plasma norepinephrine (NE) by high performance liquid chromatography-fluorimetric detection (HPLC-FLD). We also examined the morphologies of neurons and synapses in the temporal lobe by transmission electron microscopy (TEM). Our results showed that rats exposed to airport noise of 80 dB had significantly lower line crossing number (Paircraft noise of 80 dB exposure for 65 d. In conclusion, exposing rats to long-term aircraft noise affects their behaviors, plasma NE levels, and cell morphology of the temporal lobe. PMID:22135145

  12. Design and test of aircraft engine isolators for reduced interior noise

    Science.gov (United States)

    Unruh, J. F.; Scheidt, D. C.

    1982-01-01

    Improved engine vibration isolation was proposed to be the most weight and cost efficient retrofit structure-borne noise control measure for single engine general aviation aircraft. A study was carried out the objectives: (1) to develop an engine isolator design specification for reduced interior noise transmission, (2) select/design candidate isolators to meet a 15 dB noise reduction design goal, and (3) carry out a proof of concept evaluation test. Analytical model of the engine, vibration isolators and engine mount structure were coupled to an empirical model of the fuselage for noise transmission evaluation. The model was used to develop engine isolator dynamic properties design specification for reduced noise transmission. Candidate isolators ere chosen from available product literature and retrofit to a test aircraft. A laboratory based test procedure was then developed to simulate engine induced noise transmission in the aircraft for a proof of concept evaluation test. Three candidate isolator configurations were evaluated for reduced structure-borne noise transmission relative to the original equipment isolators.

  13. Plasma Fairings for Quieting Aircraft Landing Gear Noise Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase II SBIR project deals with the design, development, and testing of a "Plasma Fairing" to reduce noise on the Gulfstream G550 landing gear. The plasma...

  14. Effects of changed aircraft noise exposure on the use of outdoor recreational areas.

    Science.gov (United States)

    Krog, Norun Hjertager; Engdahl, Bo; Tambs, Kristian

    2010-11-01

    This paper examines behavioural responses to changes in aircraft noise exposure in local outdoor recreational areas near airports. Results from a panel study conducted in conjunction with the relocation of Norway's main airport in 1998 are presented. One recreational area was studied at each airport site. The samples (n = 1,264/1,370) were telephone interviewed about their use of the area before and after the change. Results indicate that changed aircraft noise exposure may influence individual choices to use local outdoor recreational areas, suggesting that careful considerations are needed in the planning of air routes over local outdoor recreational areas. However, considerable stability in use, and also fluctuations in use unrelated to the changes in noise conditions were found. Future studies of noise impacts should examine a broader set of coping mechanisms, like intra- and temporal displacement. Also, the role of place attachment, and the substitutability of local areas should be studied. PMID:21139867

  15. Effects of Changed Aircraft Noise Exposure on the Use of Outdoor Recreational Areas

    Directory of Open Access Journals (Sweden)

    Norun Hjertager Krog

    2010-11-01

    Full Text Available This paper examines behavioural responses to changes in aircraft noise exposure in local outdoor recreational areas near airports. Results from a panel study conducted in conjunction with the relocation of Norway’s main airport in 1998 are presented. One recreational area was studied at each airport site. The samples (n = 1,264/1,370 were telephone interviewed about their use of the area before and after the change. Results indicate that changed aircraft noise exposure may influence individual choices to use local outdoor recreational areas, suggesting that careful considerations are needed in the planning of air routes over local outdoor recreational areas. However, considerable stability in use, and also fluctuations in use unrelated to the changes in noise conditions were found. Future studies of noise impacts should examine a broader set of coping mechanisms, like intra- and temporal displacement. Also, the role of place attachment, and the substitutability of local areas should be studied.

  16. Aircraft noise, health, and residential sorting: evidence from two quasi-experiments.

    Science.gov (United States)

    Boes, Stefan; Nüesch, Stephan; Stillman, Steven

    2013-09-01

    We explore two unexpected changes in flight regulations to estimate the causal effect of aircraft noise on health. Detailed measures of noise are linked with longitudinal data on individual health outcomes based on the exact address information. Controlling for individual heterogeneity and spatial sorting into different neighborhoods, we find that aircraft noise significantly increases sleeping problems and headaches. Models that do not control for such heterogeneity and sorting substantially underestimate the negative health effects, which suggests that individuals self-select into residence based on their unobserved sensitivity to noise. Our study demonstrates that the combination of quasi-experimental variation and panel data is very powerful for identifying causal effects in epidemiological field studies. PMID:23836612

  17. A Psychoacoustic Evaluation of Noise Signatures from Advanced Civil Transport Aircraft

    Science.gov (United States)

    Rizzi, Stephen A.; Christian, Andrew

    2016-01-01

    The NASA Environmentally Responsible Aviation project has been successful in developing and demonstrating technologies for integrated aircraft systems that can simultaneously meet aggressive goals for fuel burn, noise and emissions. Some of the resulting systems substantially differ from the familiar tube and wing designs constituting the current civil transport fleet. This study attempts to explore whether or not the effective perceived noise level metric used in the NASA noise goal accurately reflects human subject response across the range of vehicles considered. Further, it seeks to determine, in a quantitative manner, if the sounds associated with the advanced aircraft are more or less preferable to the reference vehicles beyond any differences revealed by the metric. These explorations are made through psychoacoustic tests in a controlled laboratory environment using simulated stimuli developed from auralizations of selected vehicles based on systems noise assessments.

  18. Combined Effect of Aircraft Noise and Pollutant Emissions. ANN Model to Determine Healthy Risk Level

    OpenAIRE

    SETIA KURNIAWAN, Jermanto; KATILI, Irwan; MOERSIDIK, Setyo Sarwanto; Khardi, Salah

    2013-01-01

    Air Transportation growth increased continuously over the years. The increase in transport activity has been accompanied by an increase in the amount of energy used to provide transportation services and it is assumed to increase environmental impacts (pollutant and noise emissions). Aircraft pollutant and noise emissions are an important as a source of pollution and directly or indirectly will affect harmful to human health, ecosystems and cultural heritage. There are many methods to asses ...

  19. Aircraft Engine Noise Scattering - A Discontinuous Spectral Element Approach

    Science.gov (United States)

    Stanescu, D.; Hussaini, M. Y.; Farassat, F.

    2002-01-01

    The paper presents a time-domain method for computation of sound radiation from aircraft engine sources to the far-field. The effects of nonuniform flow around the aircraft and scattering of sound by fuselage and wings are accounted for in the formulation. Our approach is based on the discretization of the inviscid flow equations through a collocation form of the Discontinuous Galerkin spectral element method. An isoparametric representation of the underlying geometry is used in order to take full advantage of the spectral accuracy of the method. Largescale computations are made possible by a parallel implementation based on message passing. Results obtained for radiation from an axisymmetric nacelle alone are compared with those obtained when the same nacelle is installed in a generic con.guration, with and without a wing.

  20. Effects of Changed Aircraft Noise Exposure on Experiential Qualities of Outdoor Recreational Areas

    Directory of Open Access Journals (Sweden)

    Kristian Tambs

    2010-10-01

    Full Text Available The literature indicates that sound and visual stimuli interact in the impression of landscapes. This paper examines the relationship between annoyance with sound from aircraft and annoyance with other area problems (e.g., careless bicycle riding, crowding, etc., and how changes in noise exposure influence the perceived overall recreational quality of outdoor recreational areas. A panel study (telephone interviews conducted before and after the relocation of Norway’s main airport in 1998 examined effects of decreased or increased noise exposure in nearby recreational areas (n = 591/455. Sound from aircraft annoyed the largest proportion of recreationists, except near the old airport after the change. The decrease in annoyance with sound from aircraft was accompanied by significant decreases in annoyance with most of the other area problems. Near the new airport annoyance with most factors beside sound from aircraft increased slightly, but not significantly. A relationship between aircraft noise annoyance and perceived overall recreational quality of the areas was found.

  1. Applying Aircraft Noise Reduction Technologies at its Source - Progress in Technological Development

    OpenAIRE

    Gollnick, Volker; Weiss, Marco

    2011-01-01

    A survey about the principles and challanges of acoustic aspects in aviation is given. Further various technical measures ot reduce aircraft and engine noise especially investigated at various institutes of the German Aerospace Center are introduced indicating different principle solutions. At last also operational measures are presented. All aspects provide also a hint to the realistic potential of improvements

  2. Aircraft noise exposure. The cycle of modelling, monitoring and validation

    Energy Technology Data Exchange (ETDEWEB)

    Veerbeek, H.W.; Ten Have, H.B.G.

    1998-08-20

    Especially in highly dense populated areas, like the Netherlands, environmental aspects are, and always have been, a major issue in the relationship between airports and their neighbours. To deal with these aspects, airport and governmental authorities must have adequate information. In the early eighties this information often was limited to the noise level registration for a small number of (fixed) monitoring positions only. To gain additional knowledge about the environmental aspects related to the still ongoing growth of air transport, airports realised more and more complex noise and flight track monitoring systems. These complex systems provide an increasing amount of (correlated) data and functionality, related to noise and track monitoring, noise exposure calculation and complaint analysis. Information, obtained from life data, is used to validate and further optimise modelling used for e.g. airport planning purposes. As a next step, monitoring systems nowadays becomes increasingly important in what can be regarded as a closed-loop process of information gathering, processes of planning and regulation based on this. 4 refs.

  3. Number of aircraft noise events and mobility during sleep

    NARCIS (Netherlands)

    Janssen, S.A.; Vos, H.; Kamp, I. van

    2011-01-01

    Both the WHO and the EC advise on the use of Lnight as the primary indicator for sleep disturbance. Still, a key question for noise policy is whether from a public health point of view it may be advantageous to use number of events in addition to Lnight. For some effects, it may be more effective to

  4. Application of an acoustic noise removal method to aircraft-based atmospheric temperature measurements

    Science.gov (United States)

    Hugo, Ronald J.; Nowlin, Scott R.; Hahn, Ila L.; Eaton, Frank D.; McCrae, Kim A.

    2003-01-01

    An acoustic noise removal method is used to reject engine acoustical disturbances from aircraft-based atmospheric temperature measurements. Removal of engine noise from atmospheric temperature measurements allows a larger wave number range to be fit while quantifying the magnitude of atmospheric temperature turbulence. The larger wave number range was found to result in a more statistically certain spectral slope estimate, with up to a 50% reduction in the standard deviation of measured spectral slopes. The noise removal technique was found to break down under conditions of weak atmospheric temperature turbulence where the engine acoustical disturbance can be several orders of magnitude larger than atmospheric temperature turbulence.

  5. A process for the quantification of aircraft noise and emissions interdependencies

    Science.gov (United States)

    de Luis, Jorge

    The main purpose of this dissertation is to develop a process to improve actual policy-making procedures in terms of aviation environmental effects. This research work expands current practices with physics based publicly available models. The current method uses solely information provided by industry members, and this information is usually proprietary, and not physically intuitive. The process herein proposed provides information regarding the interdependencies between the environmental effects of aircraft. These interdependencies are also tied to the actual physical parameters of the aircraft and the engine, making it more intuitive for decision-makers to understand the impacts to the vehicle due to different policy scenarios. These scenarios involve the use of fleet analysis tools in which the existing aircraft are used to predict the environmental effects of imposing new stringency levels. The aircraft used are reduced to a series of coefficients that represent their performance, in terms of flight characteristics, fuel burn, noise, and emissions. These coefficients are then utilized to model flight operations and calculate what the environmental impacts of those aircraft are. If a particular aircraft does not meet the stringency to be analyzed, a technology response is applied to it, in order to meet that stringency. Depending on the level of reduction needed, this technology response can have an effect on the fuel burn characteristic of the aircraft. Another important point of the current stringency analysis process is that it does not take into account both noise and emissions concurrently, but instead, it considers them separately, one at a time. This assumes that the interdependencies between the two do not exists, which is not realistic. The latest stringency process delineated in 2004 imposed a 2% fuel burn penalty for any required improvements on NOx, no matter the type of aircraft or engine, assuming that no company had the ability to produce a

  6. Structural Acoustic Characteristics of Aircraft and Active Control of Interior Noise

    Science.gov (United States)

    Fuller, C. R.

    1998-01-01

    The reduction of aircraft cabin sound levels to acceptable values still remains a topic of much research. The use of conventional passive approaches has been extensively studied and implemented. However performance limits of these techniques have been reached. In this project, new techniques for understanding the structural acoustic behavior of aircraft fuselages and the use of this knowledge in developing advanced new control approaches are investigated. A central feature of the project is the Aircraft Fuselage Test Facility at Va Tech which is based around a full scale Cessna Citation III fuselage. The work is divided into two main parts; the first part investigates the use of an inverse technique for identifying dominant fuselage vibrations. The second part studies the development and implementation of active and active-passive techniques for controlling aircraft interior noise.

  7. Aircraft noise prediction via aeroacoustic hybrid methods - development and application of onera tools over the last decade : some examples.

    OpenAIRE

    Redonnet, S.

    2014-01-01

    International audience This article focuses on advanced noise prediction methodologies, in regard to aircraft noise mitigation. More precisely, the so-called aeroacoustic hybrid methodology is first recalled here, before illustrating its potentialities through several examples of application to realistic aircraft noise problems. Among other things, this paper highlights how Onera has contributed to the development of reliable computational methodologies over the last decade, which can now ...

  8. Prediction of Turbulent Boundary Layer Induced Noise in the Cabin of a BWB Aircraft

    Directory of Open Access Journals (Sweden)

    Joana Rocha

    2012-01-01

    Full Text Available This paper discusses the development of analytical models for the prediction of aircraft cabin noise induced by the external turbulent boundary layer (TBL. While, in previous works, the contribution of an individual panel to the cabin interior noise was considered, here, the simultaneous contribution of multiple flow-excited panels is analyzed. Analytical predictions are presented for the interior sound pressure level (SPL at different locations inside the cabin of a Blended Wing Body (BWB aircraft, for the frequency range 0–1000 Hz. The results show that the number of vibrating panels significantly affects the interior noise levels. It is shown that the average SPL, over the cabin volume, increases with the number of vibrating panels. Additionally, the model is able to predict local SPL values, at specific locations in the cabin, which are also affected with by number of vibrating panels, and are different from the average values.

  9. A solid state converter for measurement of aircraft noise and sonic boom

    Science.gov (United States)

    Zuckerwar, A. J.

    1972-01-01

    The problems inherent in present systems of instrumentation for measuring aircraft noise and sonic boom include limited frequency response, expensive connecting cables, sensitivity to cable length and type, high sensitivity to environmental conditions, and additional limitations of individual system components. Furthermore, differing requirements have resulted in the use of two different systems for aircraft noise and sonic boom measurements respectively. To alleviate these difficulties a unified system of instrumentation suitable for both types of measurements was developed. The system features a new solid state converter connected to a zero drive amplifier. The system was found insensitive to cable length and type up to at least 1000 ft and requires no impedance matching networks. The converter itself has flat frequency response from dc to 28 kHz (- 3 db), dynamic range of 72 db, and noise floor of 50 db in the band 22.4 Hz to 22.4 kHz.

  10. Aircraft Noise Prediction Program (ANOPP) Fan Noise Prediction for Small Engines

    Science.gov (United States)

    Hough, Joe W.; Weir, Donald S.

    1996-01-01

    The Fan Noise Module of ANOPP is used to predict the broadband noise and pure tones for axial flow compressors or fans. The module, based on the method developed by M. F. Heidmann, uses empirical functions to predict fan noise spectra as a function of frequency and polar directivity. Previous studies have determined the need to modify the module to better correlate measurements of fan noise from engines in the 3000- to 6000-pound thrust class. Additional measurements made by AlliedSignal have confirmed the need to revise the ANOPP fan noise method for smaller engines. This report describes the revisions to the fan noise method which have been verified with measured data from three separate AlliedSignal fan engines. Comparisons of the revised prediction show a significant improvement in overall and spectral noise predictions.

  11. Research on Aircraft Noise Evaluation System%飞机噪声评价体系研究

    Institute of Scientific and Technical Information of China (English)

    沈颖; 谢实海; 陈荣生

    2000-01-01

    The evaluation system of aircraft noise and environment noise should be integrated,because aircraft noise belongs to environment noise.At the same time,there should be some difference in the evaluation system of aircraft noise.For solving this contradiction,this article puts forward a new evaluation system of aircraft noise.This new system unifies the evaluation of aircraft noise and other environment noise effectively,and adds a new evaluation index single-event noise exposure level.The system not only considers the characteristics of aircraft noise,which is different from other traffic noise,but also adds aircraft noise to other traffic noise,which can reflect sound environment around airport really.This system has practical worthiness and theory significance.%飞机噪声的共性决定其评价体系应于环境噪声评价体系统一,而飞机噪声的个性决定其评价方法必须有别于一般环境噪声评价.本文通过对飞机噪声的共性与个性的分析,建立了一种新的飞机噪声评价体系,它不仅考虑到飞机噪声不同于其他交通噪声的特点,而且有效地统一了飞机噪声与城市区域环境噪声的评价体系.新体系可以将机场周围飞机噪声与其他交通噪声叠加,真实地反映机场周围声环境,具有一定的实用价值和理论指导意义.

  12. Design of materials for noise reduction in aircraft engines

    Energy Technology Data Exchange (ETDEWEB)

    Paun, F.; Gasser, St. [Office National d' Etudes et de Recherches Aerospatiales (ONERA), Dept. of Metallic Materials and Processing, 92 - Chatillon (France); Leylekian, L. [Office National d' Etudes et de Recherches Aerospatiales (ONERA), Dept. of Composite Systems and Materials, 92 - Chatillon (France)

    2003-01-01

    We would like to present in this paper, research that ONERA teams are making in the field of acoustic absorption materials at high temperatures. Some significant results are shown as well as some important findings for future investigation. Research performed in understanding the acoustic and mechanical behaviour of different classes of porous materials and developed processing methods will be described. Our interest was to demonstrate the feasibility of reducing noise produced by aeronautical turbo engines by means of appropriate passive acoustic treatments applied directly to the exhausters. (authors)

  13. Transport jet aircraft noise abatement in foreign countries: Growth, structure, impact. Volume 1: Europe, July 1980. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, F.A.

    1980-07-01

    The development and implementation of aircraft noise control regulations in various European states are described. The countries include the United Kingdom, France, Switzerland, Federal Republic of Germany, Sweden, Denmark, and the Netherlands. Topics discussed include noise monitoring, airport curfews, land use planning, and the government structure for noise regulation.

  14. Assessing the environmental impacts of aircraft noise and emissions

    Science.gov (United States)

    Mahashabde, Anuja; Wolfe, Philip; Ashok, Akshay; Dorbian, Christopher; He, Qinxian; Fan, Alice; Lukachko, Stephen; Mozdzanowska, Aleksandra; Wollersheim, Christoph; Barrett, Steven R. H.; Locke, Maryalice; Waitz, Ian A.

    2011-01-01

    With the projected growth in demand for commercial aviation, many anticipate increased environmental impacts associated with noise, air quality, and climate change. Therefore, decision-makers and stakeholders are seeking policies, technologies, and operational procedures that balance environmental and economic interests. The main objective of this paper is to address shortcomings in current decision-making practices for aviation environmental policies. We review knowledge of the noise, air quality, and climate impacts of aviation, and demonstrate how including environmental impact assessment and quantifying uncertainties can enable a more comprehensive evaluation of aviation environmental policies. A comparison is presented between the cost-effectiveness analysis currently used for aviation environmental policy decision-making and an illustrative cost-benefit analysis. We focus on assessing a subset of the engine NO X emissions certification stringency options considered at the eighth meeting of the International Civil Aviation Organization’s Committee on Aviation Environmental Protection. The FAA Aviation environmental Portfolio Management Tool (APMT) is employed to conduct the policy assessments. We show that different conclusions may be drawn about the same policy options depending on whether benefits and interdependencies are estimated in terms of health and welfare impacts versus changes in NO X emissions inventories as is the typical practice. We also show that these conclusions are sensitive to a variety of modeling uncertainties. While our more comprehensive analysis makes the best policy option less clear, it represents a more accurate characterization of the scientific and economic uncertainties underlying impacts and the policy choices.

  15. Description and claculation of aircraft noise; Bewertung und Berechnung von Fluglaerm

    Energy Technology Data Exchange (ETDEWEB)

    Isermann, U.; Schmid, R.

    2000-07-01

    The fundamentals of aircraft noise description are explained. Different commonly used aircraft noise descriptors are discussed with respect to their advantages and disadvantages. The principles of conventional aircraft noise calculation procedures as well as the principles of simulation procedures are described. Specific problems related to the use of conventional calculation procedures are discussed with special attention paid to the German AzB-procedure. The accuracy of conventional procedures is analyzed. The results of a comparing investigation of 9 different calculation procedures - performed within ICAO task MODEL 1 - are presented. The current status of the aircraft noise problem in Germany (special problems, revision of the German air traffic noise act) is discussed, proposals for possible improvements are made. Approximate relationships between different forms of L{sub eq} are derived from calculations based upon 12 different air traffic scenarios. (orig.) [German] Die Grundlagen der Fluglaermbewertung werden erlaeutert und unterschiedliche, gebraeuchliche Fluglaermbewertungsmasse hinsichtlich ihrer Vor- und Nachteile diskutiert. Das Prinzip von konventionellen Fluglaermberechungsverfahren sowie von Simulationsverfahren wird beschrieben. Spezielle Probleme beim Gebrauch von konventionellen Verfahren werden analysiert. Hierbei wird der Schwerpunkt auf das in Deutschland benutzte AzB-Verfahren gelegt. Die Genauigkeit von konventionellen Berechnungsverfahren wird untersucht. Die Resultate von vergleichenden Berechnungen mit 9 unterschiedlichen Verfahren, die im Rahmen des ICAO Task MODEL 1 durchgefuehrt wurden, werden vorgestellt. Der derzeitige Stand des Fluglaermproblems in Deutschland (Problemfelder, Novellierung des Fluglaermgesetzes) wird diskutiert und bewertet. Moegliche Verbesserungsvorschlaege zum AzB-Verfahren werden beschrieben. Auf der Basis von 12 Flugbetriebsfaellen werden Naeherungsbeziehungen zwischen verschiedenen L{sub eq

  16. Strategic Noise Mapping of Herakleion: The Aircraft Noise Impact as a factor of the Int. Airport relocation

    Directory of Open Access Journals (Sweden)

    Vogiatzis Konstantinos

    2014-09-01

    Full Text Available In the framework of the European Directive 2002/49/EC, the city of Herakleion in Crete Island (Greece recently completed (2013 its Strategic Noise Map (SNM and relevant Noise Action Plan (NAP. Strategic noise mapping and action plans are important tools to define the main strategies to reduce noise exposure of residents and introduce and preserve "quite zones". Within this framework and as a part of the Herakleion city Strategic Noise Mapping general a specific analysis was introduced in the urban area of Alikarnassos (east part of the city adjacent to the International Airport “Nikos Kazantzakis”. The 2nd biggest airport in Greece, airport is proposed to be relocated in Kastelli area (some 37 km south of the Herakleion city centre, far away from dense populated areas, within the next decade but in the mean time, air traffic (take of, taxi and landing procedures, especially during the extended spring and summer period, are affecting the city. This paper analyzes the extended acoustic measurement monitoring program and the modelling of environmental noise levels within the city’s SNM introducing - state of the art - qualitative surveys on the sound perception and noise annoyance by the residents as well as in depth analysis of the urban and architectural tissue. All these results have been transcribed in several maps introducing a very comprehensive evaluation tool towards an efficient noise action plan leading to the eventual relocation of the airport. This paper presents the main results of this research aiming to the evaluation of the inffluence at the inhabitants’ sonic comfort from aircraft operation.

  17. Effects of road traffic and aircraft noise upon children's academic attainments

    Science.gov (United States)

    Shield, Bridget; Dockrell, Julie; Vilatarsana, Gael

    2005-04-01

    The effects of environmental noise upon the academic performance of children aged 7 and 11 years in primary schools in London (UK) have been investigated. Noise surveys were carried out to measure levels of environmental noise during the school day outside 175 schools across London. The majority of the schools were in densely populated areas within 5 miles of central London, where road traffic was the dominant noise source. Thirty three of the schools were in a less densely populated area to the west of London near Heathrow Airport, and were subject to predominantly aircraft noise. The noise levels measured outside each school have been correlated with the results of standard tests in Reading, Writing, Mathematics, English, and Science, which are taken by all children aged 7 and 11 in England and Wales. Significant negative correlations were found between noise levels and many of the test scores, the correlations being stronger in the central London areas than in the schools around Heathrow. These results show that environmental noise has a detrimental effect upon childrens' academic performance, the effect remaining apparent when data were corrected for socio-economic factors such as social deprivation.

  18. Study of Aerodynamic Design Procedure of a Large-Scale Aircraft Noise Suppression Facility

    Science.gov (United States)

    Kawai, Masafumi; Nagai, Kiyoyuki; Aso, Shigeru

    The aerodynamic design procedure of a large-scale aircraft noise suppression facility has been developed. Flow quality required for the engine inlet flow has been determined through basic experiment. Aerodynamic design of the facility has been performed by using wind tunnel experiment and CFD. Important relationship between the length of the facility and the inlet flow quality has been found. The operational envelope of the designed facility has been estimated. Then, the aerodynamic characteristics of an actual large-scale aircraft noise suppression facility, constructed based on the new design procedure, have been measured. Obtained flow field showed good agreement with CFD results, and the effectiveness of the design procedure based on CFD and wind tunnel experiment has been confirmed. The engine operations were satisfactory under various wind conditions. Furthermore, the data under commercial operations thereafter have been collected and analyzed. As the result, the aerodynamic design procedure has been validated.

  19. A new measurement method for separating airborne and structureborne noise radiated by aircraft type panels

    Science.gov (United States)

    Mcgary, M. C.

    1982-01-01

    The theoretical basis for and experimental validation of a measurement method for separating airborne and structure borne noise radiated by aircraft type panels are presented. An extension of the two microphone, cross spectral, acoustic intensity method combined with existing theory of sound radiation of thin shell structures of various designs, is restricted to the frequency range below the coincidence frequency of the structure. Consequently, the method lends itself to low frequency noise problems such as propeller harmonics. Both an aluminum sheet and two built up aircraft panel designs (two aluminum panels with frames and stringers) with and without added damping were measured. Results indicate that the method is quick, reliable, inexpensive, and can be applied to thin shell structures of various designs.

  20. Robust active noise control in the loadmaster area of a military transport aircraft.

    Science.gov (United States)

    Kochan, Kay; Sachau, Delf; Breitbach, Harald

    2011-05-01

    The active noise control (ANC) method is based on the superposition of a disturbance noise field with a second anti-noise field using loudspeakers and error microphones. This method can be used to reduce the noise level inside the cabin of a propeller aircraft. However, during the design process of the ANC system, extensive measurements of transfer functions are necessary to optimize the loudspeaker and microphone positions. Sometimes, the transducer positions have to be tailored according to the optimization results to achieve a sufficient noise reduction. The purpose of this paper is to introduce a controller design method for such narrow band ANC systems. The method can be seen as an extension of common transducer placement optimization procedures. In the presented method, individual weighting parameters for the loudspeakers and microphones are used. With this procedure, the tailoring of the transducer positions is replaced by adjustment of controller parameters. Moreover, the ANC system will be robust because of the fact that the uncertainties are considered during the optimization of the controller parameters. The paper describes the necessary theoretic background for the method and demonstrates the efficiency in an acoustical mock-up of a military transport aircraft.

  1. Robust active noise control in the loadmaster area of a military transport aircraft.

    Science.gov (United States)

    Kochan, Kay; Sachau, Delf; Breitbach, Harald

    2011-05-01

    The active noise control (ANC) method is based on the superposition of a disturbance noise field with a second anti-noise field using loudspeakers and error microphones. This method can be used to reduce the noise level inside the cabin of a propeller aircraft. However, during the design process of the ANC system, extensive measurements of transfer functions are necessary to optimize the loudspeaker and microphone positions. Sometimes, the transducer positions have to be tailored according to the optimization results to achieve a sufficient noise reduction. The purpose of this paper is to introduce a controller design method for such narrow band ANC systems. The method can be seen as an extension of common transducer placement optimization procedures. In the presented method, individual weighting parameters for the loudspeakers and microphones are used. With this procedure, the tailoring of the transducer positions is replaced by adjustment of controller parameters. Moreover, the ANC system will be robust because of the fact that the uncertainties are considered during the optimization of the controller parameters. The paper describes the necessary theoretic background for the method and demonstrates the efficiency in an acoustical mock-up of a military transport aircraft. PMID:21568404

  2. Nonlinear acoustic propagation of launch vehicle and military jet aircraft noise

    Science.gov (United States)

    Gee, Kent L.

    2010-10-01

    The noise from launch vehicles and high-performance military jet aircraft has been shown to travel nonlinearly as a result of an amplitude-dependent speed of sound. Because acoustic pressure compressions travel faster than rarefactions, the waveform steepens and shocks form. This process results in a very different (and readily audible) noise signature and spectrum than predicted by linear models. On-going efforts to characterize the nonlinearity using statistical and spectral measures are described with examples from recent static tests of solid rocket boosters and the F-22 Raptor.

  3. Anticipated Effectiveness of Active Noise Control in Propeller Aircraft Interiors as Determined by Sound Quality Tests

    Science.gov (United States)

    Powell, Clemans A.; Sullivan, Brenda M.

    2004-01-01

    Two experiments were conducted, using sound quality engineering practices, to determine the subjective effectiveness of hypothetical active noise control systems in a range of propeller aircraft. The two tests differed by the type of judgments made by the subjects: pair comparisons in the first test and numerical category scaling in the second. Although the results of the two tests were in general agreement that the hypothetical active control measures improved the interior noise environments, the pair comparison method appears to be more sensitive to subtle changes in the characteristics of the sounds which are related to passenger preference.

  4. A solid-state converter for measurement of aircraft noise and sonic boom

    Science.gov (United States)

    Zuckerwar, A. J.; Shope, W. W.

    1974-01-01

    A solid-state converter, used in a system of instrumentation for measuring aircraft noise and sonic boom, features a dual-gate FET mixer and an output stage designed for compatibility with a zero drive amplifier. With a half-inch condenser microphone the converter itself has an operating frequency range from dc-28 kHz (-3 dB), a dynamic range of 72 dB, and a noise floor of 50 dB in the band from 22.4 Hz to 22.4 kHz; the system requires no impedance matching networks and is insensitive to cable length up to at least 3000 ft.

  5. Evaluation of an Aircraft Concept With Over-Wing, Hydrogen-Fueled Engines for Reduced Noise and Emissions

    Science.gov (United States)

    Guynn, Mark D.; Olson, Erik D.

    2002-01-01

    This report describes the analytical modeling and evaluation of an unconventional commercial transport aircraft concept designed to address aircraft noise and emission issues. A strut-braced wing configuration with overwing, ultra-high bypass ratio, hydrogen fueled turbofan engines is considered. Estimated noise and emission characteristics are compared to a conventional configuration designed for the same mission and significant benefits are identified. The design challenges and technology issues which would have to be addressed to make the concept a viable alternative to current aircraft designs are discussed. This concept is one of the "Quiet Green Transport" aircraft concepts studied as part of NASA's Revolutionary Aerospace Systems Concepts (RASC) Program. The RASC Program seeks to develop revolutionary concepts that address strategic objectives of the NASA Enterprises, such as reducing aircraft noise and emissions, and to identify enabling advanced technology requirements for the concepts.

  6. Effects of Changed Aircraft Noise Exposure on Experiential Qualities of Outdoor Recreational Areas

    OpenAIRE

    Kristian Tambs; Norun Hjertager Krog; Bo Engdahl

    2010-01-01

    The literature indicates that sound and visual stimuli interact in the impression of landscapes. This paper examines the relationship between annoyance with sound from aircraft and annoyance with other area problems (e.g., careless bicycle riding, crowding, etc.), and how changes in noise exposure influence the perceived overall recreational quality of outdoor recreational areas. A panel study (telephone interviews) conducted before and after the relocation of Norway’s main airport in 1998 ex...

  7. Determining the direction of causality between psychological factors and aircraft noise annoyance

    OpenAIRE

    Maarten Kroesen; Eric J. E. Molin; Bert van Wee

    2010-01-01

    In this paper, an attempt is made to establish the direction of causality between a range of psychological factors and aircraft noise annoyance. For this purpose, a panel model was estimated within a structural equation modeling approach. Data were gathered from two surveys conducted in April 2006 and April 2008, respectively, among the same residents living within the 45 Level day-evening-night contour of Amsterdam Airport Schiphol, the largest airport in the Netherlands (n=250). A surprisin...

  8. Definition of 1992 Technology Aircraft Noise Levels and the Methodology for Assessing Airplane Noise Impact of Component Noise Reduction Concepts

    Science.gov (United States)

    Kumasaka, Henry A.; Martinez, Michael M.; Weir, Donald S.

    1996-01-01

    This report describes the methodology for assessing the impact of component noise reduction on total airplane system noise. The methodology is intended to be applied to the results of individual study elements of the NASA-Advanced Subsonic Technology (AST) Noise Reduction Program, which will address the development of noise reduction concepts for specific components. Program progress will be assessed in terms of noise reduction achieved, relative to baseline levels representative of 1992 technology airplane/engine design and performance. In this report, the 1992 technology reference levels are defined for assessment models based on four airplane sizes - an average business jet and three commercial transports: a small twin, a medium sized twin, and a large quad. Study results indicate that component changes defined as program final goals for nacelle treatment and engine/airframe source noise reduction would achieve from 6-7 EPNdB reduction of total airplane noise at FAR 36 Stage 3 noise certification conditions for all of the airplane noise assessment models.

  9. Effects of low intensity noise from aircraft or from neighbourhood on cognitive learning and electrophysiological stress responses.

    Science.gov (United States)

    Trimmel, Michael; Atzlsdorfer, Jürgen; Tupy, Nina; Trimmel, Karin

    2012-11-01

    The effects of low intensity noise on cognitive learning and autonomous physiological processes are of high practical relevance but are rarely addressed in empirical investigations. This study investigated the impact of neighbourhood noise (of 45 dB[A], n=20) and of noise coming from passing aircraft (of 48 dB[A] peak amplitude presented once per minute; n=19) during computer based learning of different texts (with three types of text structure, i.e. linear text, hierarchic hypertext, and network hypertext) in relation to a control group (35 dB[A], n=20). Using a between subjects design, reproduction scores, heart rate, and spontaneous skin conductance fluctuations were compared. Results showed impairments of reproduction in both noise conditions. Additionally, whereas in the control group and the neighbourhood noise group scores were better for network hypertext structure than for hierarchic hypertext, no effect of text structure on reproduction appeared in the aircraft noise group. Compared to the control group, for most of the learning period the number of spontaneous skin conductance fluctuations was higher for the aircraft noise group. For the neighbourhood noise group, fluctuations were higher during pre- and post task periods when noise stimulation was still present. Additionally, during the last 5 min of the 15 min learning period, an increased heart rate was found in the aircraft noise group. Data indicate remarkable cognitive and physiological effects of low intensity background noise. Some aspects of reproduction were impaired in the two noise groups. Cognitive learning, as indicated by reproduction scores, was changed structurally in the aircraft noise group and was accompanied by higher sympathetic activity. An additional cardiovascular load appeared for aircraft noise when combined with time pressure as indicated by heart rate for the announced last 5 min of the learning period during aircraft noise with a peak SPL of even 48 dB(A). Attentional

  10. Effects of low intensity noise from aircraft or from neighbourhood on cognitive learning and electrophysiological stress responses.

    Science.gov (United States)

    Trimmel, Michael; Atzlsdorfer, Jürgen; Tupy, Nina; Trimmel, Karin

    2012-11-01

    The effects of low intensity noise on cognitive learning and autonomous physiological processes are of high practical relevance but are rarely addressed in empirical investigations. This study investigated the impact of neighbourhood noise (of 45 dB[A], n=20) and of noise coming from passing aircraft (of 48 dB[A] peak amplitude presented once per minute; n=19) during computer based learning of different texts (with three types of text structure, i.e. linear text, hierarchic hypertext, and network hypertext) in relation to a control group (35 dB[A], n=20). Using a between subjects design, reproduction scores, heart rate, and spontaneous skin conductance fluctuations were compared. Results showed impairments of reproduction in both noise conditions. Additionally, whereas in the control group and the neighbourhood noise group scores were better for network hypertext structure than for hierarchic hypertext, no effect of text structure on reproduction appeared in the aircraft noise group. Compared to the control group, for most of the learning period the number of spontaneous skin conductance fluctuations was higher for the aircraft noise group. For the neighbourhood noise group, fluctuations were higher during pre- and post task periods when noise stimulation was still present. Additionally, during the last 5 min of the 15 min learning period, an increased heart rate was found in the aircraft noise group. Data indicate remarkable cognitive and physiological effects of low intensity background noise. Some aspects of reproduction were impaired in the two noise groups. Cognitive learning, as indicated by reproduction scores, was changed structurally in the aircraft noise group and was accompanied by higher sympathetic activity. An additional cardiovascular load appeared for aircraft noise when combined with time pressure as indicated by heart rate for the announced last 5 min of the learning period during aircraft noise with a peak SPL of even 48 dB(A). Attentional

  11. The effects of road traffic and aircraft noise exposure on children′s episodic memory: The RANCH Project

    Directory of Open Access Journals (Sweden)

    Mark Matheson

    2010-01-01

    Full Text Available Previous studies have found that chronic exposure to aircraft noise has a negative effect on children′s performance on tests of episodic memory. The present study extended the design of earlier studies in three ways: firstly, by examining the effects of two noise sources, aircraft and road traffic, secondly, by examining exposure-effect relationships, and thirdly, by carrying out parallel field studies in three European countries, allowing cross-country comparisons to be made. A total of 2844 children aged between 8 years 10 months and 12 years 10 months (mean age 10 years 6 months completed classroom-based tests of cued recall, recognition memory and prospective memory. Questionnaires were also completed by the children and their parents in order to provide information about socioeconomic context. Multilevel modeling analysis revealed aircraft noise to be associated with an impairment of recognition memory in a linear exposure-effect relationship. The analysis also found road traffic noise to be associated with improved performance on cued recall in a linear exposure-effect relationship. No significant association was found between exposure to aircraft noise and cued recall or prospective memory. Likewise, no significant association was found between road traffic noise and recognition or prospective memory. Taken together, these findings indicate that exposure to aircraft noise and road traffic noise can impact on certain aspects of children′s episodic memory.

  12. Arousal from sleep - The physiological and subjective effects of a 15 dB/A/ reduction in aircraft flyover noise

    Science.gov (United States)

    Levere, T. E.; Davis, N.

    1977-01-01

    The present research was concerned with whether or not a 15 dB(A) reduction in overall noise level would lessen the sleep disturbing properties of jet aircraft flyover noise and, if less disturbing, whether this would be subjectively appreciated by the sleeping individual. The results indicate that a reduction of 15 dB (A) does result in less sleep disruption but only during sleep characterized by fast-wave electroencephalographic activity. During sleep characterized by slow-wave electroencephalographic activity, such a reduction in the sleep-disturbing properties of jet aircraft noise has little effect. Moreover, even when effective during fast-wave sleep, the decreased arousal produced by the lower noise levels is not subjectively appreciated by the individual in terms of his estimate of the quality of his night's sleep. Thus, reducing the overall noise level of jet aircraft flyovers by some 15 dB(A), is, at best, minimally beneficial to sleep.

  13. Transport jet aircraft noise abatement in foreign countries: Growth, structure, impact. Volume 2: Pacific Basin, August 1980. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, F.A.

    1980-08-01

    Noise control measures at the international airports of Hawaii, New Zealand, Australia, Hong Kong, Japan, and Singapore were studied. Factors in noise control, such as government structure are examined. The increasing power of environmental agencies vis-a-vis aviation departments is noted. The following methods of dealing with aircraft noise are examined by type of control: noise at the source control noise emmission controls, zoning, building codes, subsidies for relocation, insulation, loss in property values, and for TV, radio and telephone interference and noise-related landing charges.

  14. Noise simulation of aircraft engine fans by the boundary element method

    Science.gov (United States)

    Pyatunin, K. R.; Arkharova, N. V.; Remizov, A. E.

    2016-07-01

    Numerical simulation results of the civil aircraft engine fan stage noise in the far field are presented. Non-steady-state rotor-stator interaction is calculated the commercial software that solves the Navier-Stokes equations using differentturbulence models. Noise propagation to the far acoustic field is calculated by the boundary element method using acoustic Lighthill analogies without taking into account the mean current in the air inlet duct. The calculated sound pressure levels at points 50 m from the engine are presented, and the directional patterns of the acoustic radiation are shown. The use of the eddy resolving turbulence model to calculate rotor-stator interaction increases the accuracy in predicting fan stage noise.

  15. Implications of the road traffic and aircraft noise exposure and children's cognition and health (RANCH) study results for classroom acoustics

    Science.gov (United States)

    Stansfeld, Stephen A.; Clark, Charlotte

    2005-04-01

    Studies in West London have found associations between aircraft noise exposure and childrens' cognitive performance. This has culminated in the RANCH Study examining exposure-effect associations between aircraft and road traffic noise exposure and cognitive performance and health. The RANCH project, the largest cross-sectional study of noise and childrens health, examined 2844 children, 9-10 years old, from 89 schools around three major airports: in the Netherlands, Spain and the United Kingdom. Children were selected by external aircraft and road traffic noise exposure at school predicted from noise contour maps, modeling and on-site measurements. A substudy indicated high internal levels of noise within classrooms. Schools were matched for socioeconomic position within countries. Cognitive and health outcomes were measured by standardized tests and questionnaires administered in the classroom. A parental questionnaire collected information on socioeconomic position, parental education and ethnicity. Linear exposure-effect associations were found between chronic aircraft noise exposure and impairment of reading comprehension and recognition memory, maintained after adjustment for mothers education, socioeconomic factors, longstanding illness and classroom insulation. Road traffic noise exposure was linearly associated with episodic memory. The implications of these results for childrens' learning environments will be discussed. [Work supported by European Community (QLRT-2000-00197) Vth framework program.

  16. Measurements of the tonal component of cavity noise and comparison with theory. [aircraft noise

    Science.gov (United States)

    Block, P. J. W.

    1977-01-01

    The frequency of the tonal noise generated by a flow-excited rectangular cavity was measured using Mach numbers ranging from 0.05 to 0.40, and cavity length-to-depth ratios varying from 0.1 to 8. The data are used to evaluate a current prediction method, and good agreement is shown. Measurements of the minimum streamwise cavity length required for oscillation were also made.

  17. Emotionality in response to aircraft noise: A report of development work

    Science.gov (United States)

    Klaus, P. A.

    1975-01-01

    A literature search and pilot study conducted to investigate the topic of emotional response to aircraft noise are described. A Tell-A-Story Technique was developed for use in the pilot study which required respondents to make up stories for a series of aircraft-related and non-aircraft-related pictures. A content analysis of these stories was made. The major finding was that response patterns varied among three groups of respondents - those currently living near airports, those who had lived near airports in the past, and those who had never lived near airports. Negative emotional feelings toward aircraft were greatest among respondents who had lived near airports in the past but no longer did. A possible explanation offered for this finding was that people currently living near airports might adapt to the situation by denying some of their negative feelings, which they might feel more free to express after they had moved away from the situation. Other techniques used in the pilot study are also described, including group interviews and a word association task.

  18. Određivanje buke radi sertifikacije mlaznih aviona / Procedures in the noise certification of jet aircraft

    Directory of Open Access Journals (Sweden)

    Gordana Jurin

    2005-01-01

    Full Text Available U radu su prikazane osnovne teorijske postavke i matematički modeli koji su značajni za obradu akustičkih i neakustičkih podataka u procesu određivanja buke mlaznih aviona prema međunarodnom standardu ICAO, Annex 16, za potrebe sertiflkacije. Proces obuhvata i postupak eliminacije efekata ambijentalnog šuma iz signala avionske buke. Kao primer, data je praktična primena navedenog postupka na rezultate merenja za avion G-2A. / This paper presents a basic theoretical scheme and a mathematical model that is used to calculate jet aircraft noise level for certification purposes in accordance with the international standard ICAO Annex 16. In this process acoustic and nonacoustic data are used. The process also includes the procedure for eliminating ambient noise effects out of the aircraft noise signal. This procedure was applied in the case of noise measurement results for the G-2Ajet aircraft.

  19. Exposure-effect relations between aircraft and road traffic noise exposure at school and reading comprehension: the RANCH project.

    OpenAIRE

    Clark, Charlotte; Martin, Rocio; van Kempen, Elise; Alfred, Tamuno; Head, Jenny; Davies, Hugh W.; Haines, Mary M; Lopez Barrio, Isabel; Matheson, Mark; Stansfeld, Stephen A

    2006-01-01

    Transport noise is an increasingly prominent feature of the urban environment, making noise pollution an important environmental public health issue. This paper reports on the 2001-2003 RANCH project, the first cross-national epidemiologic study known to examine exposure-effect relations between aircraft and road traffic noise exposure and reading comprehension. Participants were 2,010 children aged 9-10 years from 89 schools around Amsterdam Schiphol, Madrid Barajas, and London Heathrow airp...

  20. Analytical study of interior noise control by fuselage design techniques on high-speed, propeller-driven aircraft

    Science.gov (United States)

    Revell, J. D.; Balena, F. J.; Koval, L. R.

    1980-01-01

    The acoustical treatment mass penalties required to achieve an interior noise level of 80 dBA for high speed, fuel efficient propfan-powered aircraft are determined. The prediction method used is based on theory developed for the outer shell dynamics, and a modified approach for add-on noise control element performance. The present synthesis of these methods is supported by experimental data. Three different sized aircraft are studied, including a widebody, a narrowbody and a business sized aircraft. Noise control penalties are calculated for each aircraft for two kinds of noise control designs: add-on designs, where the outer wall structure cannot be changed, and advanced designs where the outer wall stiffness level and the materials usage can be altered. For the add-on designs, the mass penalties range from 1.7 to 2.4 percent of the takeoff gross weight (TOGW) of the various aircraft, similar to preliminary estimates. Results for advanced designs show significant reductions of the mass penalties. For the advanced aluminum designs the penalties are 1.5% of TOGW, and for an all composite aircraft the penalties range from 0.74 to 1.4% of TOGW.

  1. Autonomous Slat-Cove-Filler Device for Reduction of Aeroacoustic Noise Associated with Aircraft Systems

    Science.gov (United States)

    Turner, Travis L. (Inventor); Kidd, Reggie T. (Inventor); Lockard, David P (Inventor); Khorrami, Mehdi R. (Inventor); Streett, Craig L. (Inventor); Weber, Douglas Leo (Inventor)

    2016-01-01

    A slat cove filler is utilized to reduce airframe noise resulting from deployment of a leading edge slat of an aircraft wing. The slat cove filler is preferably made of a super elastic shape memory alloy, and the slat cove filler shifts between stowed and deployed shapes as the slat is deployed. The slat cove filler may be configured such that a separate powered actuator is not required to change the shape of the slat cove filler from its deployed shape to its stowed shape and vice-versa. The outer contour of the slat cove filler preferably follows a profile designed to maintain accelerating flow in the gap between the slat cove filler and wing leading edge to provide for noise reduction.

  2. Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors

    Science.gov (United States)

    Burdisso, Ricardo (Inventor); Fuller, Chris R. (Inventor); O'Brien, Walter F. (Inventor); Thomas, Russell H. (Inventor); Dungan, Mary E. (Inventor)

    1996-01-01

    An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.

  3. An Epidemiological Prospective Study of Children’s Health and Annoyance Reactions to Aircraft Noise Exposure in South Africa

    Directory of Open Access Journals (Sweden)

    Joseph Seabi

    2013-07-01

    Full Text Available The purpose of this study was to investigate health and annoyance reactions to change in chronic exposure to aircraft noise on a sample of South African children. It was the intention of this study to examine if effects of noise on health and annoyance can be demonstrated. If so, whether such effects persist over time, or whether such effects are reversible after the cessation of exposure to noise. A cohort of 732 children with a mean age of 11.1 (range = 8–14 participated at baseline measurements in Wave 1 (2009, and 649 (mean age = 12.3; range = 9–15 and 174 (mean age = 13.3; range = 10–16 children were reassessed in Wave 2 (2010 and Wave 3 (2011 after the relocation of the airport, respectively. The findings revealed that the children who were exposed to chronic aircraft noise continued to experience significantly higher annoyance than their counterparts in all the waves at school, and only in Wave 1 and Wave 2 at home. Aircraft noise exposure did not have adverse effects on the children’s self-reported health outcomes. Taken together, these findings suggest that chronic exposure to aircraft noise may have a lasting impact on children’s annoyance, but not on their subjective health rating. This is one of the first longitudinal studies of this nature in the African continent to make use of an opportunity resulting from the relocation of airport.

  4. An epidemiological prospective study of children's health and annoyance reactions to aircraft noise exposure in South Africa.

    Science.gov (United States)

    Seabi, Joseph

    2013-07-01

    The purpose of this study was to investigate health and annoyance reactions to change in chronic exposure to aircraft noise on a sample of South African children. It was the intention of this study to examine if effects of noise on health and annoyance can be demonstrated. If so, whether such effects persist over time, or whether such effects are reversible after the cessation of exposure to noise. A cohort of 732 children with a mean age of 11.1 (range = 8-14) participated at baseline measurements in Wave 1 (2009), and 649 (mean age = 12.3; range = 9-15) and 174 (mean age = 13.3; range = 10-16) children were reassessed in Wave 2 (2010) and Wave 3 (2011) after the relocation of the airport, respectively. The findings revealed that the children who were exposed to chronic aircraft noise continued to experience significantly higher annoyance than their counterparts in all the waves at school, and only in Wave 1 and Wave 2 at home. Aircraft noise exposure did not have adverse effects on the children's self-reported health outcomes. Taken together, these findings suggest that chronic exposure to aircraft noise may have a lasting impact on children's annoyance, but not on their subjective health rating. This is one of the first longitudinal studies of this nature in the African continent to make use of an opportunity resulting from the relocation of airport. PMID:23823713

  5. Is there an association between aircraft noise exposure and the incidence of hypertension? A meta-analysis of 16784 participants.

    Science.gov (United States)

    Huang, Di; Song, XuPing; Cui, Qi; Tian, Jinhui; Wang, Quan; Yang, Kehu

    2015-01-01

    To determine if aircraft noise exposure causes an increased incidence of hypertension among residents near airports. We conducted a meta-analysis of observational studies to evaluate the association between aircraft noise exposure and the incidence of hypertension. PubMed, Embase, Web of Science, the Cochrane Library, and the Chinese Biomedical Literature Database were searched without any restrictions. Odds ratios (ORs) with 95% confidence intervals (CIs) were extracted. The pooled ORs were calculated using both the fixed effects model and random effects model. All analyses were performed using STATA version 12.0 software (Stata Corporation, College Station, TX, USA). We examined five studies, comprising a total of 16,784 residents. The overall OR for hypertension in residents with aircraft noise exposure was 1.63 (95% CI, 1.14-2.33), and one of our included studies showed that there was no evidence that aircraft noise is a risk factor for hypertension in women. According to our subgroup analysis, the summary OR for the incidence was 1.31 (95% CI, 0.85-2.02) with I2 of 80.7% in women and 1.36 (95% CI, 1.15-1.60) with moderate heterogeneity in men. The pooled OR for the incidence of hypertension in residents aged over 55 years and under 55 years was 1.66 (95% CI, 1.21-2.27) with no heterogeneity and 1.78 (95% CI, 1.33-2.39) with I2 of 29.4%, respectively. The present meta-analysis suggests that aircraft noise could contribute to the prevalence of hypertension, but the evidence for a relationship between aircraft noise exposure and hypertension is still inconclusive because of limitations in study populations, exposure characterization, and adjustment for important confounders. PMID:25774612

  6. Is there an association between aircraft noise exposure and the incidence of hypertension? A meta-analysis of 16784 participants

    Directory of Open Access Journals (Sweden)

    Di Huang

    2015-01-01

    Full Text Available To determine if aircraft noise exposure causes an increased incidence of hypertension among residents near airports. We conducted a meta-analysis of observational studies to evaluate the association between aircraft noise exposure and the incidence of hypertension. PubMed, Embase, Web of Science, the Cochrane Library, and the Chinese Biomedical Literature Database were searched without any restrictions. Odds ratios (ORs with 95% confidence intervals (CIs were extracted. The pooled ORs were calculated using both the fixed effects model and random effects model. All analyses were performed using STATA version 12.0 software (Stata Corporation, College Station, TX, USA. We examined five studies, comprising a total of 16,784 residents. The overall OR for hypertension in residents with aircraft noise exposure was 1.63 (95% CI, 1.14-2.33, and one of our included studies showed that there was no evidence that aircraft noise is a risk factor for hypertension in women. According to our subgroup analysis, the summary OR for the incidence was 1.31 (95% CI, 0.85-2.02 with I2 of 80.7% in women and 1.36 (95% CI, 1.15-1.60 with moderate heterogeneity in men. The pooled OR for the incidence of hypertension in residents aged over 55 years and under 55 years was 1.66 (95% CI, 1.21-2.27 with no heterogeneity and 1.78 (95% CI, 1.33-2.39 with I2 of 29.4%, respectively. The present meta-analysis suggests that aircraft noise could contribute to the prevalence of hypertension, but the evidence for a relationship between aircraft noise exposure and hypertension is still inconclusive because of limitations in study populations, exposure characterization, and adjustment for important confounders.

  7. A comparison of a laboratory and field study of annoyance and acceptability of aircraft noise exposures. [human reactions and tolerance

    Science.gov (United States)

    Borsky, P. N.

    1977-01-01

    Residents living in close, middle and distant areas from JFK Airport were included in a field interview and laboratory study. Judgments were made of simulated aircraft noise exposures of comparable community indoor noise levels and mixes of aircraft. Each group of subjects judged the levels of noise typical for its distance area. Four different numbers of flyovers were tested: less than average for each area, the approximate average, the peak number, or worst day, and above peak number. The major findings are: (1) the reported integrated field annoyance is best related to the annoyance reported for the simulated approximate worst day exposure in the laboratory; (2) annoyance is generally less when there are fewer aircraft flyovers, and the subject has less fear of crashes and more favorable attitudes toward airplanes; (3) beliefs in harmful health effects and misfeasance by operators of aircraft are also highly correlated with fear and noise annoyance; (4) in direct retrospective comparisons of number of flights, noise levels and annoyance, subjects more often said the worst day laboratory exposured more like their usual home environments; and (5) subjects do not expect an annoyance-free environment. Half of the subjects can accept an annoyance level of 5 to 6 from a possible annoyance range of 0 to 9, 28% can live with an annoyance intensity of 7, and only 5% can accept the top scores of 8 to 9.

  8. Aircraft noise effects on sleep: a systematic comparison of EEG awakenings and automatically detected cardiac activations

    International Nuclear Information System (INIS)

    Polysomnography is the gold standard for investigating noise effects on sleep, but data collection and analysis are sumptuous and expensive. We recently developed an algorithm for the automatic identification of cardiac activations associated with cortical arousals, which uses heart rate information derived from a single electrocardiogram (ECG) channel. We hypothesized that cardiac activations can be used as estimates for EEG awakenings. Polysomnographic EEG awakenings and automatically detected cardiac activations were systematically compared using laboratory data of 112 subjects (47 male, mean ± SD age 37.9 ± 13 years), 985 nights and 23 855 aircraft noise events (ANEs). The probability of automatically detected cardiac activations increased monotonically with increasing maximum sound pressure levels of ANEs, exceeding the probability of EEG awakenings by up to 18.1%. If spontaneous reactions were taken into account, exposure–response curves were practically identical for EEG awakenings and cardiac activations. Automatically detected cardiac activations may be used as estimates for EEG awakenings. More investigations are needed to further validate the ECG algorithm in the field and to investigate inter-individual differences in its ability to predict EEG awakenings. This inexpensive, objective and non-invasive method facilitates large-scale field studies on the effects of traffic noise on sleep

  9. Methods for designing treatments to reduce interior noise of predominant sources and paths in a single engine light aircraft

    Science.gov (United States)

    Hayden, Richard E.; Remington, Paul J.; Theobald, Mark A.; Wilby, John F.

    1985-01-01

    The sources and paths by which noise enters the cabin of a small single engine aircraft were determined through a combination of flight and laboratory tests. The primary sources of noise were found to be airborne noise from the propeller and engine casing, airborne noise from the engine exhaust, structureborne noise from the engine/propeller combination and noise associated with air flow over the fuselage. For the propeller, the primary airborne paths were through the firewall, windshield and roof. For the engine, the most important airborne path was through the firewall. Exhaust noise was found to enter the cabin primarily through the panels in the vicinity of the exhaust outlet although exhaust noise entering the cabin through the firewall is a distinct possibility. A number of noise control techniques were tried, including firewall stiffening to reduce engine and propeller airborne noise, to stage isolators and engine mounting spider stiffening to reduce structure-borne noise, and wheel well covers to reduce air flow noise.

  10. Aircraft optimal approach minimizing noise, fuel consumption and pollutant emissions. In : Modélisation du trafic. Actes du groupe de travail 2007, Coll. Actes Inrets N123

    OpenAIRE

    Khardi, S.; Abdallah, L; Konovalova, E.; Nahayo, F.; HOUACINE, M

    2009-01-01

    Aircraft noise and air pollution are considered to be one of the most significant environmental concerns on the local community of modern cities, affecting people living in particular near airports. Previous researches suggested that people living around airports are a high risk group, vulnerable to the effects of aircraft operations. This is supported by evidence that aircraft noise and pollution exposure have also been associated with reduced psychological well-being, lower self-reported qu...

  11. Active control of counter-rotating open rotor interior noise in a Dornier 728 experimental aircraft

    Science.gov (United States)

    Haase, Thomas; Unruh, Oliver; Algermissen, Stephan; Pohl, Martin

    2016-08-01

    The fuel consumption of future civil aircraft needs to be reduced because of the CO2 restrictions declared by the European Union. A consequent lightweight design and a new engine concept called counter-rotating open rotor are seen as key technologies in the attempt to reach this ambitious goals. Bearing in mind that counter-rotating open rotor engines emit very high sound pressures at low frequencies and that lightweight structures have a poor transmission loss in the lower frequency range, these key technologies raise new questions in regard to acoustic passenger comfort. One of the promising solutions for the reduction of sound pressure levels inside the aircraft cabin are active sound and vibration systems. So far, active concepts have rarely been investigated for a counter-rotating open rotor pressure excitation on complex airframe structures. Hence, the state of the art is augmented by the preliminary study presented in this paper. The study shows how an active vibration control system can influence the sound transmission of counter-rotating open rotor noise through a complex airframe structure into the cabin. Furthermore, open questions on the way towards the realisation of an active control system are addressed. In this phase, an active feedforward control system is investigated in a fully equipped Dornier 728 experimental prototype aircraft. In particular, the sound transmission through the airframe, the coupling of classical actuators (inertial and piezoelectric patch actuators) into the structure and the performance of the active vibration control system with different error sensors are investigated. It can be shown that the active control system achieves a reduction up to 5 dB at several counter-rotating open rotor frequencies but also that a better performance could be achieved through further optimisations.

  12. The impact of aircraft noise exposure on South African children′s reading comprehension: The moderating effect of home language

    Directory of Open Access Journals (Sweden)

    Joseph Seabi

    2012-01-01

    Full Text Available Given the limited studies conducted within the African continent, the purpose of this study was to investigate the impact of chronic aircraft noise exposure and the moderating effect of home language on the learners′ reading comprehension. The sample comprised 437 (52% senior primary learners exposed to high levels of aircraft noise (Experimental group and 337 (48% learners residing in a quieter area (Control group. Of these, 151 learners in the Experimental group spoke English as a first language (EFL and 162 spoke English as a second language (ESL. In the Control group, the numbers were similarly divided (EFL n = 191; ESL n = 156. A univariate General Linear Model was used to investigate the effects of aircraft noise exposure and language on reading comprehension, while observing for the possible impact of intellectual ability, gender, and socioeconomic status on the results. A significant difference was observed between ESL and EFL learners in favor of the latter (F 1,419 = 21.95, P =.000. In addition a substantial and significant interaction effect was found between the experimental and control groups for the two language groups. For the EFL speakers there was a strong reduction in reading comprehension in the aircraft noise group. By contrast this difference was not significant for the ESL speakers. Implications of the findings and suggestions for further research are made in the article.

  13. The impact of aircraft noise exposure on South African children's reading comprehension: the moderating effect of home language.

    Science.gov (United States)

    Seabi, Joseph; Cockcroft, Kate; Goldschagg, Paul; Greyling, Mike

    2012-01-01

    Given the limited studies conducted within the African continent, the purpose of this study was to investigate the impact of chronic aircraft noise exposure and the moderating effect of home language on the learners' reading comprehension. The sample comprised 437 (52%) senior primary learners exposed to high levels of aircraft noise (Experimental group) and 337 (48%) learners residing in a quieter area (Control group). Of these, 151 learners in the Experimental group spoke English as a first language (EFL) and 162 spoke English as a second language (ESL). In the Control group, the numbers were similarly divided (EFL n = 191; ESL n = 156). A univariate General Linear Model was used to investigate the effects of aircraft noise exposure and language on reading comprehension, while observing for the possible impact of intellectual ability, gender, and socioeconomic status on the results. A significant difference was observed between ESL and EFL learners in favor of the latter (F 1,419 = 21.95, P =.000). In addition a substantial and significant interaction effect was found between the experimental and control groups for the two language groups. For the EFL speakers there was a strong reduction in reading comprehension in the aircraft noise group. By contrast this difference was not significant for the ESL speakers. Implications of the findings and suggestions for further research are made in the article. PMID:23117540

  14. Special analysis of community annoyance with aircraft noise reported by residents in the vicinity of JFK Airport, 1972

    Science.gov (United States)

    Borsky, P. N.

    1975-01-01

    During the summer of 1972, about 1500 residents were interviewed twice in 11 communities near JFK airport. Detailed aircraft operations reports were also collected for this period, and an effort has been made to analyze recorded human response data in relation to a number of physical exposure parameters. A series of exposure indexes, based on an arithmetic integration of aircraft operations, were correlated with summated aircraft noise annoyance responses. None of these correlations were as good as the CNR index which assumes a logrithmetic integration of numbers of aircraft exposures and includes a day-night differential weighting of 10:1. There were substantial variations in average annoyance responses among communities with similar CNR exposures, substantiating previous findings that attitudinal and other personal variables also play an important role in determining annoyance differences.

  15. Aircraft

    Science.gov (United States)

    Hibbs, Bart D.; Lissaman, Peter B. S.; Morgan, Walter R.; Radkey, Robert L.

    1998-01-01

    This disclosure provides a solar rechargeable aircraft that is inexpensive to produce, is steerable, and can remain airborne almost indefinitely. The preferred aircraft is a span-loaded flying wing, having no fuselage or rudder. Travelling at relatively slow speeds, and having a two-hundred foot wingspan that mounts photovoltaic cells on most all of the wing's top surface, the aircraft uses only differential thrust of its eight propellers to turn. Each of five sections of the wing has one or more engines and photovoltaic arrays, and produces its own lift independent of the other sections, to avoid loading them. Five two-sided photovoltaic arrays, in all, are mounted on the wing, and receive photovoltaic energy both incident on top of the wing, and which is incident also from below, through a bottom, transparent surface. The aircraft is capable of a top speed of about ninety miles per hour, which enables the aircraft to attain and can continuously maintain altitudes of up to sixty-five thousand feet. Regenerative fuel cells in the wing store excess electricity for use at night, such that the aircraft can sustain its elevation indefinitely. A main spar of the wing doubles as a pressure vessel that houses hydrogen and oxygen gasses for use in the regenerative fuel cell. The aircraft has a wide variety of applications, which include weather monitoring and atmospheric testing, communications, surveillance, and other applications as well.

  16. High intensity interior aircraft noise increases the risk of high diastolic blood pressure in Indonesian Air Force pilots

    Directory of Open Access Journals (Sweden)

    Minarma Siagian

    2009-12-01

    Full Text Available Aim: To analyze the effects of aircraft noise, resting pulse rate, and other factors on the risk of high diastolic blood pressure (DBP in Indonesian Air Force pilots.Methods: A nested case-control study was conducted using data extracted from annual medical check-ups indoctrination aerophysiologic training records at the Saryanto Aviation and Aerospace Health Institute (LAKESPRA in Jakarta from January 2003 – September 2008. For analysis of DBP: the case group with DBP ≥ 90 mmHg were compared with contral group with DBP < 79 mmHG. One case matched to 12 controls.Results: Out of 567 pilots, 544 (95.9% had complete medical records. For this analysis there were 40 cases of high DBP and 480 controls for DBP. Pilots exposed to aircraft noise 90-95 dB rather than 70-80 dB had a 2.7-fold increase for high DBP [adjusted odds ratio (ORa = 2.70; 95% confi dence interval (CI = 1.05-6.97]. Pilots with resting pulse rates of ≥ 81/minute rather than ≤ 80/minute had a 2.7-fold increase for high DBP (ORa = 2.66; 95% CI = 1.26-5.61. In terms of total fl ight hours, pilots who had 1401-11125 hours rather than 147-1400 hours had a 3.2-fold increase for high DBP (ORa = 3.18; 95% CI = 1.01-10.03.Conclusion: High interior aircraft noise, high total flight hours,  and high resting pulse rate, increased risk for high DBP. Self assessment of resting pulse rate can be used to control the risk of high DBP. (Med J Indones 2009; 276: 276-82Keywords: diastolic blood pressure, aircraft noise, resting pulse rate, military pilots

  17. A general model for aircraft noise calculation%飞机噪声计算通用模型研究

    Institute of Scientific and Technical Information of China (English)

    刘洲; 蔡良才; 方华; 邵斌; 杜宜霖; 孙捷

    2012-01-01

    In order to perfect and standardize the current aircraft noise calculation method. Here, the basic theory for disassembling a flight path based on geometrical elements of beeline segment and curve one was presented, a systematic and general aircraft noise calculation model was built. An example was used to prove the feasibility and practicability of the model. With the proposed model, some technical problems in actual estimation of aircraft noise were solved, the calculation method was standardized and the whole assessing process became more intuitive, intelligent and scientific.%为完善和规范现行的飞机噪声计算方法,根据飞行航线的几何特点,基于“直线段”和“曲线段”这两个基本的航线元素提出了航线分解的思想,阐述了其基本原理,建立了系统的飞机噪声计算通用模型,并实例验证了该模型的可行性和实用性.该模型解决了实际噪声环境影响评价工作中的相关技术问题,规范了噪声计算方法,使整个评价工作更直观、更智能、更科学.

  18. 多通道有源噪声控制系统设计%Reduction of Noise in Chinese Y-7 Aircraft Using Active Noise Control (ANC)

    Institute of Scientific and Technical Information of China (English)

    吴亚锋; 黎中伟; 任辉; 李江红

    2001-01-01

    Active noise control, as applied to engineering projects, began around 1990. We designed a multi-channel active noise control (ANC) system for reducing the noise in front cabin in Chinese Y-7 propeller driven aircraft. In ANC applications, in order to reduce effectively the noise level in a large space, we have to match at any time the generated secondary sound field with the original primary sound field, so that a percentage of the entire primary noise field is effectively cancelled out by the entire secondary noise field. Via analyzing ANC time sequences, we developed a multi-channel adaptive control system that can simultaneously detect multiple error inputs and produce multiple canceling outputs. Our system consists of PC as main controller, TMS320-C30 DSP chip as slave processor, 16 A/D input channels and 8 D/A output channels. Applying our system to Chinese Y-7 aircraft appears to be successful; test results show that noise level of Y-7′s blade pass frequency (BPF) and its secondary harmonic frequency (2BPF) are attenuated by 13.4 dB and 5.5 dB respectively. Work remains to be done before our system becomes a part of Y-7 aircraft in actual flights.%基于实时数字信号处理系统理论,讨论有源噪声控制系统的电子设计方法。通过对控制时序的分析,设计了一实时多通道自适应控制系统,该系统以PC为主控机,以DSP TMS320-C30为从处理机,具有多路传感器同时输入和扬声器同时输出通道。该系统被应用于国产某型螺桨飞机的舱内噪声控制,取得了满意的降噪效果。

  19. Development of SCR Aircraft takeoff and landing procedures for community noise abatement and their impact on flight safety

    Science.gov (United States)

    Grantham, W. D.; Smith, P. M.

    1980-01-01

    Piloted simulator studies to determine takeoff and landing procedures for a supersonic cruise transport concept that result in predicted community noise levels which meet current Federal Aviation Administration (FAA) standards are discussed. The results indicate that with the use of advanced procedures, the subject simulated aircraft meets the FAA traded noise levels during takeoff and landing utilizing average flight crew skills. The advanced takeoff procedures developed involved violating three of the current Federal Aviation Regulations (FAR) noise test conditions. These were: (1) thrust cutbacks at altitudes below 214 meters (700 ft); (2) thrust cutback level below those presently allowed; and (3) configuration change, other than raising the landing gear. It was not necessary to violate any FAR noise test conditions during landing approach. It was determined that the advanced procedures developed do not compromise flight safety. Automation of some of the aircraft functions reduced pilot workload, and the development of a simple head-up display to assist in the takeoff flight mode proved to be adequate.

  20. [Social and economic consequences of night-time aircraft noise in the vicinity of Frankfurt/Main airport].

    Science.gov (United States)

    Greiser, E; Glaeske, G

    2013-03-01

    A prospective calculation of disease-related social and economic costs due to night-time aircraft noise in the vicinity of Frankfurt/Main airport was performed for the calendar years 2012-2021. It was based on risk estimates for a variety of diagnostic entities (cardiovascular disease, depression, psychosis, diabetes mellitus, dementia and Alzheimer's disease, all cancers except malignancies of the respiratory system) from a previous case-control study on more than 1 million persons enrolled in compulsory sickness funds in the vicinity of the Cologne-Bonn airport, on disease-related cost estimates performed by the German Federal Statistical Office for the calender years 2002-2008, and calculations of the population exposed to night-time aircraft noise in the vicinity of Frankfurt/Main airport (2005 aircraft routes and flight frequencies). Total estimated costs came to more than 1.5 billion € with an excess of 23 400 cases of diseases treated in hospitals and of 3 400 subsequent deaths. PMID:23456959

  1. Airframe Noise Prediction of a Full Aircraft in Model and Full Scale Using a Lattice Boltzmann Approach

    Science.gov (United States)

    Fares, Ehab; Duda, Benjamin; Khorrami, Mehdi R.

    2016-01-01

    Unsteady flow computations are presented for a Gulfstream aircraft model in landing configuration, i.e., flap deflected 39deg and main landing gear deployed. The simulations employ the lattice Boltzmann solver PowerFLOW(Trademark) to simultaneously capture the flow physics and acoustics in the near field. Sound propagation to the far field is obtained using a Ffowcs Williams and Hawkings acoustic analogy approach. Two geometry representations of the same aircraft are analyzed: an 18% scale, high-fidelity, semi-span model at wind tunnel Reynolds number and a full-scale, full-span model at half-flight Reynolds number. Previously published and newly generated model-scale results are presented; all full-scale data are disclosed here for the first time. Reynolds number and geometrical fidelity effects are carefully examined to discern aerodynamic and aeroacoustic trends with a special focus on the scaling of surface pressure fluctuations and farfield noise. An additional study of the effects of geometrical detail on farfield noise is also documented. The present investigation reveals that, overall, the model-scale and full-scale aeroacoustic results compare rather well. Nevertheless, the study also highlights that finer geometrical details that are typically not captured at model scales can have a non-negligible contribution to the farfield noise signature.

  2. Elastomeric Structural Attachment Concepts for Aircraft Flap Noise Reduction - Challenges and Approaches to Hyperelastic Structural Modeling and Analysis

    Science.gov (United States)

    Sreekantamurthy, Thammaiah; Turner, Travis L.; Moore, James B.; Su, Ji

    2014-01-01

    Airframe noise is a significant part of the overall noise of transport aircraft during the approach and landing phases of flight. Airframe noise reduction is currently emphasized under the Environmentally Responsible Aviation (ERA) and Fixed Wing (FW) Project goals of NASA. A promising concept for trailing-edge-flap noise reduction is a flexible structural element or link that connects the side edges of the deployable flap to the adjacent main-wing structure. The proposed solution is distinguished by minimization of the span-wise extent of the structural link, thereby minimizing the aerodynamic load on the link structure at the expense of increased deformation requirement. Development of such a flexible structural link necessitated application of hyperelastic materials, atypical structural configurations and novel interface hardware. The resulting highly-deformable structural concept was termed the FLEXible Side Edge Link (FLEXSEL) concept. Prediction of atypical elastomeric deformation responses from detailed structural analysis was essential for evaluating feasible concepts that met the design constraints. The focus of this paper is to describe the many challenges encountered with hyperelastic finite element modeling and the nonlinear structural analysis of evolving FLEXSEL concepts. Detailed herein is the nonlinear analysis of FLEXSEL concepts that emerged during the project which include solid-section, foamcore, hollow, extended-span and pre-stressed concepts. Coupon-level analysis performed on elastomeric interface joints, which form a part of the FLEXSEL topology development, are also presented.

  3. Optimizing Noise Attenuation in Aircraft Exhaust Ducts Employing Passive and Active Absorbing Splitters and Struts Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA requires accurate numerical simulation of high bypass nacelle acoustics and the development of advanced nacelle absorption techniques to reduce engine noise...

  4. Application of analysis techniques for low frequency interior noise and vibration of commercial aircraft

    Science.gov (United States)

    Landmann, A. E.; Tillema, H. F.; Macgregor, G. R.

    1992-01-01

    Finite element analysis (FEA), statistical energy analysis (SEA), and a power flow method (computer program PAIN) were used to assess low frequency interior noise associated with advanced propeller installations. FEA and SEA models were used to predict cabin noise and vibration and evaluate suppression concepts for structure-borne noise associated with the shaft rotational frequency and harmonics (less than 100 Hz). SEA and PAIN models were used to predict cabin noise and vibration and evaluate suppression concepts for airborne noise associated with engine radiated propeller tones. Both aft-mounted and wing-mounted propeller configurations were evaluated. Ground vibration test data from a 727 airplane modified to accept a propeller engine were used to compare with predictions for the aft-mounted propeller. Similar data from the 767 airplane was used for the wing-mounted comparisons.

  5. Separation of airborne and structureborne noise radiated by plates constructed of conventional and composite materials with applications for prediction of interior noise paths in propeller driven aircraft. Ph.D. Thesis

    Science.gov (United States)

    Mcgary, M. C.

    1986-01-01

    The anticipated application of advanced turboprop propulsion systems and use of composite materials in primary structure is expected to increase the interior noise of future aircraft to unacceptability high levels. The absence of technically and economically feasible noise source-path diagnostic tools has been a primer obstacle in the development of efficient noise control treatments for propeller driven aircraft. A new diagnostic method which permits the separation and prediction of the fully coherent airborne and structureborne components of the sound radiated by plates or thin shells has been developed. Analytical and experimental studies of the proposed method were performed on plates constructed of both conventional and composite materials. The results of the study indicate that the proposed method can be applied to a variety of aircraft materials, could be used in flight, and has fewer encumbrances than the other diagnostic tools currently available. The study has also revealed that the noise radiation of vibrating plates in the low frequency regime due to combined airborne and structureborne inputs possesses a strong synergistic nature. The large influence of the interaction between the airborne and structureborne terms has been hitherto ignored by researchers of aircraft interior noise problems.

  6. Aircraft Engine Noise Scattering by Fuselage and Wings: A Computational Approach

    Science.gov (United States)

    Stanescu, D.; Hussaini, M. Y.; Farassat, F.

    2003-01-01

    The paper presents a time-domain method for computation of sound radiation from aircraft engine sources to the far-field. The effects of nonuniform flow around the aircraft and scattering of sound by fuselage and wings are accounted for in the formulation. The approach is based on the discretization of the inviscid flow equations through a collocation form of the Discontinuous Galerkin spectral element method. An isoparametric representation of the underlying geometry is used in order to take full advantage of the spectral accuracy of the method. Large-scale computations are made possible by a parallel implementation based on message passing. Results obtained for radiation from an axisymmetric nacelle alone are compared with those obtained when the same nacelle is installed in a generic configuration, with and without a wing.

  7. Sound Generation in the Presence of Moving Surfaces with Application to Internally Generated Aircraft Engine Noise

    Science.gov (United States)

    Goldstein, Marvin E.; Envia, E.

    2002-01-01

    In many cases of technological interest solid boundaries play a direct role in the aerodynamic sound generation process and their presence often results in a large increase in the acoustic radiation. A generalized treatment of the emission of sound from moving boundaries is presented. The approach is similar to that of Ffowcs Williams and Hawkings (1969) but the effect of the surrounding mean flow is explicitly accounted for. The results are used to develop a rational framework for the prediction of internally generated aero-engine noise. The final formulas suggest some new noise sources that may be of practical significance.

  8. 飞机噪声预测与仿真技术研究%Study on Technique of Prediction and Simulation of Aircraft Noise

    Institute of Scientific and Technical Information of China (English)

    刘洲; 蔡良才; 陈黎明; 邵斌; 魏海亮; 桂小渝

    2013-01-01

      为弥补现行飞机噪声环境影响评价方法的不足,根据飞行航线的几何特点,设计了一套科学实用飞机噪声评价量计算算法,给出了算法的基本思想和仿真模型。将GIS技术引入到飞机噪声预测与仿真过程中,探讨了GIS在噪声等值线的绘制和后续评价过程中的应用。实例表明,飞机噪声预测模型运行状况良好,计算噪声较为准确,GIS能极大地提升模型的空间数据处理与分析能力,使整个评价过程更科学、更直观。%In order to make up the shortage of current aircraft noise evaluation method, a scientific and practical algorithm of aircraft noise metric was designed based on the geometric characteristics of flight path. Its basic theory and simulation model were given. The GIS technique was introduced into the prediction and simulation of the aircraft noise, and its application to noise contours protracting and noise evaluation was discussed. The example indicates that the model works well for prediction of the aircraft noise. It can give the right results of noise. GIS can greatly improve the model’s capabilities for processing and analyzing spatial data, making the evaluation more intelligent, more scientific and more intuitive.

  9. The effect of the number of aircraft noise events on sleep quality

    NARCIS (Netherlands)

    Janssen, S.A.; Centen, M.R.; Vos, H.; Kamp, I. van

    2014-01-01

    Background Both the WHO and the EC recommend the use of Lnight as the primary indicator for sleep disturbance. Still, a key question for noise policy is whether the prediction of sleep quality could be improved by taking the number of events into account in addition to Lnight. Objectives The current

  10. Aircraft interior noise prediction using a structural-acoustic analogy in NASTRAN modal synthesis

    Science.gov (United States)

    Grosveld, Ferdinand W.; Sullivan, Brenda M.; Marulo, Francesco

    1988-01-01

    The noise induced inside a cylindrical fuselage model by shaker excitation is investigated theoretically and experimentally. The NASTRAN modal-synthesis program is used in the theoretical analysis, and the predictions are compared with experimental measurements in extensive graphs. Good general agreement is obtained, but the need for further refinements to account for acoustic-cavity damping and structural-acoustic interaction is indicated.

  11. 国外控制机场飞机噪声影响的措施%Noise Impact Control Measures of Aircrafts in Foreign Airports

    Institute of Scientific and Technical Information of China (English)

    尹建坤; 赵仁兴; 田瑞丽; 马丽霞

    2015-01-01

    介绍了国外机场控制飞机噪声影响的主要做法。国际民航组织发行的《飞机噪声管理的平衡做法指导》主要是从减少噪声源,土地使用规划和管理,减噪运行程序和运行限制等方面控制噪声污染。美国采取的控制措施主要有做好航空规划和城市规划的协调发展,根据机场周边敏感点情况设计影响居民较少的飞行程序,并给出了机场噪声控制措施汇总。欧盟采取的控制措施是建立安静的空中交通系统,技术上需要有安静的飞机,低噪声程序和社会影响管理等。举例说明了目前国外几个机场采取的降噪措施。结合国外机场飞机噪声控制措施,提出了适合我国的飞机噪声控制措施建议。%The main approaches to control the impact of aircraft noise in foreign airports were introduced. The“Bal-ance approach guidance for aircraft noise management”by ICAO has provided the approaches for noise pollution control in the aspects of noise source reduction, land-use planning and management, noise abatement operational procedures and opera-tion restrictions, etc. In the United States, the main control measures are the balancing between aviation development plan-ning and urban development planning, designing the flight procedures with less affect on residents according to the distribu-tion of sensitive points around the airport, and summarizing the airport noise control measures. Control measure by the EU is to establish a quiet air traffic system, including the use of technically quiet aircrafts, low-noise flight procedures and social impact management. The noise reduction measures currently used by several foreign airports were illustrated. Summarizing the aircraft noise control measures in foreign airports, some aircraft noise control measures for domestic airports were sug-gested.

  12. Discussion of the large aircraft nacelle reduction technology on noise%大型民机短舱降噪技术综述

    Institute of Scientific and Technical Information of China (English)

    任方; 李海波; 陈严华; 刘振皓; 秦朝红

    2015-01-01

    Aircraft nacelle noise is one of the most important problems in aircraft design and environment protection. The problem is so complex and involves many domains that lots of researchers are interested in. This paper gives a brief overview of the airframe noise including mechanism of large aircraft noise and the main sources,foundation of internal research. The noise source of mechanism and reduction method are discussed, Finally, the orientation methods and approach of the nacelle noise research are advanced,this is very important problem to research the comfort,economy and safety of aircraft, there is important practical significance for our country to develop long-range aircraft project.%飞机短舱噪声是飞机设计和环境保护面临的重大问题之一,因其问题复杂涉及的学科多,一直备受关注.对大型民机噪声的国内外研究状况进行概述,总结了国内研究基础,分析飞机噪声的本质和来源,针对飞机短舱讨论了噪声产生机理及降噪方法,最后提出了当前亟需研究的方向、方法和途径,对于飞机的安全性、经济性、舒适性都是很重要的课题,对于发展国家大飞机工程有很重要的现实意义.

  13. Theoretical vibro-acoustic modeling of acoustic noise transmission through aircraft windows

    Science.gov (United States)

    Aloufi, Badr; Behdinan, Kamran; Zu, Jean

    2016-06-01

    In this paper, a fully vibro-acoustic model for sound transmission across a multi-pane aircraft window is developed. The proposed model is efficiently applied for a set of window models to perform extensive theoretical parametric studies. The studied window configurations generally simulate the passenger window designs of modern aircraft classes which have an exterior multi-Plexiglas pane, an interior single acrylic glass pane and a dimmable glass ("smart" glass), all separated by thin air cavities. The sound transmission loss (STL) characteristics of three different models, triple-, quadruple- and quintuple-paned windows identical in size and surface density, are analyzed for improving the acoustic insulation performances. Typical results describing the influence of several system parameters, such as the thicknesses, number and spacing of the window panes, on the transmission loss are then investigated. In addition, a comparison study is carried out to evaluate the acoustic reduction capability of each window model. The STL results show that the higher frequencies sound transmission loss performance can be improved by increasing the number of window panels, however, the low frequency performance is decreased, particularly at the mass-spring resonances.

  14. Noise

    Science.gov (United States)

    Noise is all around you, from televisions and radios to lawn mowers and washing machines. Normally, you ... sensitive structures of the inner ear and cause noise-induced hearing loss. More than 30 million Americans ...

  15. 民用飞机降噪优化方案分析%Optimization Schemes of Civil Aircraft Noise Reduction Analysis

    Institute of Scientific and Technical Information of China (English)

    夏天; 闫国华

    2014-01-01

    The advanced noise reduction technology of the National Aeronautics and Space Administration ( NASA) are ana-lyzed, which greatly reduced aircraft noise levels."Mute"project aircraft can provide a reference for the future development of large aircrafts in China.For the current type of aircrafts, based on the meet of the noise airworthiness methods, the appropri-ate noise reduction program is analyzed.The single event noise value algorithm is use to calculate the effective perceived noise level (EPNdB).The result shows that under program of the steeper approach,the Boeing 737-800 can reduce the noise level of 8EPNdB at most, the area of contour of 30%can reduce at most.Under the thrust cutback scheme, the Boeing 737-800 can reduce the noise level of 3.96EPNdB at the height of 600 meters.By comparing analysis, it can provide a reference for the development of China′s large aircraft.%分析美国航空航天局(NASA)先进降噪理论和模型,"静音"飞机具有前瞻性。对于现役机型,在符合现行噪声适航方法的基础上,分析适航降噪程序。利用单事件噪声值算法对有效感觉噪声级( EPNdB )进行计算,结果显示在大角度进近程序下,波音737-800飞机可最多降低8有效感觉噪声分贝,噪声等值线面积最多可减少30%。利用减推力起飞降噪程序,波音737-800飞机在600 m高度时可降低3.96有效感觉噪声分贝。通过对比分析可为我国大飞机等研制提供借鉴。

  16. Effects of nocturnal aircraft noise on sleep: results from the ''quiet air traffic'' project; Wirkungen des Nachtfluglaerms auf den Schlaf: Ergebnisse aus dem Projekt ''Leiser Flugverkehr''

    Energy Technology Data Exchange (ETDEWEB)

    Samel, A.; Basner, M.; Maass, H.; Mueller, U.; Quehl, J.; Wenzel, J. [Deutsches Zentrum fuer Luft- und Raumfahrt (DLR) in der Helmholtz-Gemeinschaft (HGF), Inst. fuer Luft- und Raumfahrtmedizin, Koeln (Germany)

    2005-07-01

    In 192 sleep-healthy subjects (18 to 65 y) effects of nocturnal aircraft noise on sleep, stress, performance and subjective factors were investigated in 2240 nights under laboratory and field conditions. In the sleep lab, 112 volunteers were subjected to aircraft noise events by varying numbers and noise levels during 9 nights within a period of 13 nights. 16 further subjects served as control group (i.e. without any noise). 64 subjects were studied in the vicinity of Cologne-Bonn airport during 9 nights. Polysomnographical and acoustical recordings, determination of excretion rates of stress hormones from night urines, performance tests and questionnaires were conducted during all days for the assessment of nocturnal aircraft noise effects. By simultaneous recording of electrophysiological and acoustical data the probability of noise induced awakenings was estimated. Performance and most of psychological parameters did not show significant dose-effect relationships, whereas annoyance did. Epinephrine and norepinephrine did not change under aircraft noise, cortisol did change only in the lab. In the lab, a comparison between all noisy nights and noise-free baseline nights exhibited a non-significant 2-min. reduction of sleep and a 4-min. decrease of slow-wave sleep. In the field, awakenings caused by aircraft noise were detected above a threshold of 33 dB(A) ''at the sleeper's ear''. All effects were much less pronounced in the field than in the lab. For the first time, precise dose-effect curves between maximum aircraft noise event levels and electrophysiologically detectable awakenings, and a threshold were empirically established. The results of these studies broadens the knowledge on aircraft noise induced sleep disturbances and immediate consequences for the next day. (orig.)

  17. Some comparisons of the flyover noise characteristics of DC-9 aircraft having refanned and hardwalled JT8D engines, with special reference to measurement and analysis procedures

    Science.gov (United States)

    Hosier, R. N.

    1976-01-01

    Flyover noise measurements were made (using Federal Aviation Regulations, part 36 procedures) of two DC-9 aircraft, one equipped with refanned JT8D-109 engines and the other equipped with hardwalled JT8D-9 engines. NASA analyses show a refan centerline noise reduction of about 9.1 EPNdB and 10.0 EPNdB for takeoff with cutback and 50 deg. flap landing approach, respectively. A comparison of refan and hardwall PNLTM spectra shows that the refan noise reduction may be attributed to lower jet noise levels on takeoff and reduced high-frequency tonal content on landing approach. A general description of the test procedures and results are included along with detailed descriptions of the measurement and analysis systems.

  18. 机场航空噪声监测系统及其作用%Aircraft noise monitoring and control around airport

    Institute of Scientific and Technical Information of China (English)

    余成轩

    2012-01-01

    Combined with the practice of aircraft noise monitoring system installation at Shanghai Hongqiao International Airport, this paper introduced the development of the system in the world. The main function, system structure and key-technology are recommended. Also, how to reduce the aircraft noise with the help of monitoring system is discussed.%结合上海虹桥国际机场建设航空噪声监测系统的具体实践,探讨了机场航空噪声监测系统在国内外的发展与应用,系统关键技术及其在机场噪声管理中的作用.

  19. Acute effects of aircraft noise on cardiovascular admissions - an interrupted time-series analysis of a six-day closure of London Heathrow Airport caused by volcanic ash.

    Science.gov (United States)

    Pearson, Tim; Campbell, Michael J; Maheswaran, Ravi

    2016-08-01

    Acute noise exposure may acutely increase blood pressure but the hypothesis that acute exposure to aircraft noise may trigger cardiovascular events has not been investigated. This study took advantage of a six-day closure of a major airport in April 2010 caused by volcanic ash to examine if there was a decrease in emergency cardiovascular hospital admissions during or immediately after the closure period, using an interrupted daily time-series study design. The population living within the 55dB(A) noise contour was substantial at 0.7 million. The average daily admission count was 13.9 (SD 4.4). After adjustment for covariates, there was no evidence of a decreased risk of hospital admission from cardiovascular disease during the closure period (relative risk 0.97 (95% CI 0.75-1.26)). Using lags of 1-7 days gave similar results. Further studies are needed to investigate if transient aircraft noise exposure can trigger acute cardiovascular events. PMID:27494958

  20. Development of a SMA-Based Slat-Cove Filler for Reduction of Aeroacoustic Noise Associated With Transport-Class Aircraft Wings

    Science.gov (United States)

    Turner, Travis L.; Kidd, Reggie T.; Hartl, Darren J.; Scholten, William D.

    2013-01-01

    Airframe noise is a significant part of the overall noise produced by typical, transport-class aircraft during the approach and landing phases of flight. Leading-edge slat noise is a prominent source of airframe noise. The concept of a slat-cove filler was proposed in previous work as an effective means of mitigating slat noise. Bench-top models were deployed at 75% scale to study the feasibility of producing a functioning slat-cove filler. Initial results from several concepts led to a more-focused effort investigating a deformable structure based upon pseudoelastic SMA materials. The structure stows in the cavity between the slat and main wing during cruise and deploys simultaneously with the slat to guide the aerodynamic flow suitably for low noise. A qualitative parametric study of SMA-enabled, slat-cove filler designs was performed on the bench-top. Computational models were developed and analyses were performed to assess the displacement response under representative aerodynamic load. The bench-top and computational results provide significant insight into design trades and an optimal design.

  1. Sound transmission through the walls of light aircraft: An investigation of structure-borne noise in a Handley Page 137 Jetstream 3 aircraft

    Science.gov (United States)

    Bernhard, R. J.; Wohlever, C.

    1988-01-01

    This study indicates that the structureborne noise due to wing/vortex interation for the Handley Page-137 Jetstream may be significant at frequencies above 500 Hz. It was found that by preventing such interaction, noise reductions between 1 to 3 dB were attainable. However, this study did not show any significant contribution due to this phenomena at the first blade passage tone. It is suspected that the wing/vortex interaction effect varies from plane to plane.

  2. 基于航空噪声指标的高速列车观光区噪声评价%Noise Evaluation in the Tourist Cabin of High-speed Train by Using Aircraft Noise Criterion

    Institute of Scientific and Technical Information of China (English)

    张捷; 肖新标; 张玉梅; 王瑞乾; 王谛; 金学松

    2013-01-01

    Based on field measurements,the noise characteristics in the tourist cabin of a high-speed train are analyzed at a high running speed between 300 to 400 km/h.So far,there is still no a unified criterion in the word to evaluate the noise level in the carriage of high-speed train reasonably,while A-weighted sound level has a shortcoming in the noise evaluation.In order to further clear the shortcoming,A-weighted sound level is discussed through the detailed contrast to white noise combined with increasing sound level in different frequency bands.An aircraft noise evaluation index is used to evaluate the interior noise of the high-speed train.The obtained results indicate that:the noise in the tourist cabin of the high-speed train is dominated by the components of low and middle frequencies.Such a noise would be underestimated when A-weighted sound level is used.There is high similarity of frequency characteristics between interior noise of high-speed train and it of aircraft.The aircraft noise evaluation index is more suitable for the characteristic evaluation of interior noise of high-speed train.This paper could provide evidence for framing new proper noise evaluation criterion for high-speed train.%基于现场测试结果,对300~400 km/h速度下高速列车观光区噪声进行分析,明确车内噪声动态特性.由于国内外还没有统一的高速列车车内噪声评价标准,传统的A计权声压级又在噪声评价中存在不足之处.为研究A计权声压级是否适合高速列车车内噪声评价,通过白噪声对比、分频段声压级比例增加等方法,讨论使用A计权声压级评价车内噪声时的不足之处.运用航空噪声评价指标对高速列车车内噪声进行评价研究.研究结果表明,300 km/h以上高速列车车内噪声具有显著的中低频特性,使用A计权声压级评价会低估车内噪声水平.高速列车观光区噪声频谱特性和飞机舱内噪声频谱特性具有很高的相似性,选择

  3. Does exposure to aircraft noise increase the mortality from cardiovascular disease in the population living in the vicinity of airports? Results of an ecological study in France

    Directory of Open Access Journals (Sweden)

    Anne-Sophie Evrard

    2015-01-01

    Full Text Available The impact of aircraft noise on health is of growing concern. We investigated the relationship between this exposure and mortality from cardiovascular disease, coronary heart disease, myocardial infarction, and stroke. We performed an ecological study on 161 communes (commune being the smallest administrative unit in France close to the following three major French airports: Paris-Charles de Gaulle, Lyon Saint-Exupéry, and Toulouse-Blagnac. The mortality data were provided by the French Center on Medical Causes of Death for the period 2007-2010. Based on the data provided by the French Civil Aviation Authority, a weighted average exposure to aircraft noise (L den AEI was computed at the commune level. A Poisson regression model with commune-specific random intercepts, adjusted for potential confounding factors including air pollution, was used to investigate the association between mortality rates and L den AEI. Positive associations were observed between L den AEI and mortality from cardiovascular disease [adjusted mortality rate ratio (MRR per 10 dB(A increase in L den AEI = 1.18; 95% confidence interval (CI: 1.11-1.25], coronary heart disease [MRR = 1.24 (1.12-1.36], and myocardial infarction [MRR = 1.28 (1.11-1.46]. Stroke mortality was more weakly associated with L den AEI [MRR = 1.08 (0.97-1.21]. These significant associations were not attenuated after the adjustment for air pollution. The present ecological study supports the hypothesis of an association between aircraft noise exposure and mortality from cardiovascular disease, coronary heart disease, and myocardial infarction. However, the potential for ecological bias and the possibility that this association could be due to residual confounding cannot be excluded.

  4. Does exposure to aircraft noise increase the mortality from cardiovascular disease in the population living in the vicinity of airports? Results of an ecological study in France.

    Science.gov (United States)

    Evrard, Anne-Sophie; Bouaoun, Liacine; Champelovier, Patricia; Lambert, Jacques; Laumon, Bernard

    2015-01-01

    The impact of aircraft noise on health is of growing concern. We investigated the relationship between this exposure and mortality from cardiovascular disease, coronary heart disease, myocardial infarction, and stroke. We performed an ecological study on 161 communes (commune being the smallest administrative unit in France) close to the following three major French airports: Paris-Charles de Gaulle, Lyon Saint-Exupéry, and Toulouse-Blagnac. The mortality data were provided by the French Center on Medical Causes of Death for the period 2007-2010. Based on the data provided by the French Civil Aviation Authority, a weighted average exposure to aircraft noise (L den AEI) was computed at the commune level. A Poisson regression model with commune-specific random intercepts, adjusted for potential confounding factors including air pollution, was used to investigate the association between mortality rates and L den AEI. Positive associations were observed between L den AEI and mortality from cardiovascular disease [adjusted mortality rate ratio (MRR) per 10 dB(A) increase in L den AEI = 1.18; 95% confidence interval (CI): 1.11-1.25], coronary heart disease [MRR = 1.24 (1.12-1.36)], and myocardial infarction [MRR = 1.28 (1.11-1.46]. Stroke mortality was more weakly associated with L den AEI [MRR = 1.08 (0.97-1.21]. These significant associations were not attenuated after the adjustment for air pollution. The present ecological study supports the hypothesis of an association between aircraft noise exposure and mortality from cardiovascular disease, coronary heart disease, and myocardial infarction. However, the potential for ecological bias and the possibility that this association could be due to residual confounding cannot be excluded. PMID:26356375

  5. Primena sistema za monitoring buke i MatLab-a za proračun nivoa avionske buke / Noise monitoring system and MatLab application for aircraft noise level calculation

    Directory of Open Access Journals (Sweden)

    Milorad Pavlović

    2007-07-01

    Full Text Available U radu je prikazan način primene sistema za monitoring buke, terminal NMT 3637B i softver 7802, firme Brüel & Kjær, u procesu sertifikacije mlaznih aviona, prema ICAO, standardu Annex 16 i algoritam za proračun EPNL nivoa buke (Effective Perceived Noise Level, koji je kreiran u okruženju MatLab. Ovim softverom sublimirani su svi potrebni ulazni podaci, akustički i neakustički, radi dobijanja traženog nivoa i svih međurezultata neophodnih za formiranje konačnog izveštaja koji se dostavlja vazduhoplovnim vlastima. / This paper presents the use of noise monitoring system, terminal NMT 3637B and software 7802, Brüel & Kjær in process of jet aircraft noise certification according to standard ICAO Annex 16 and the algoritam for calculating EPNL noise level (Effective Perceived Noise Level that we created in MatLab environment. This software sublimated all necessary input parameters, acoustic and non acoustic in purpose of getting final result and intermediate data. Those data are important for reporting to the certificating authority.

  6. 螺桨飞机舱内噪声的主动控制%Active control of propeller induced aircraft cabin noise

    Institute of Scientific and Technical Information of China (English)

    吴亚锋; 任辉; 李江红

    2001-01-01

    文章讨论主动噪声控制技术在螺桨飞机舱内降噪中的应用。一实用的多通道自适应控制系统被开发,并被应用于国产运七螺桨飞机的舱内噪声控制,取得了满意的降噪效果。%An experiment using active control technique to attenuate propeller aircraft cabin noise is presented in this paper. A multichannel adaptive active noise control (ANC) system is developed. A control experiment is fulfilled in chinese Y7 arcraft and satisfiedresults is obtained.

  7. Laboratory study of the effects of sidewall treatment, source directivity and temperature on the interior noise of a light aircraft fuselage

    Science.gov (United States)

    Heitman, K. E.; Mixson, J. S.

    1986-01-01

    This paper describes a laboratory study of add-on {coustic treatments for a twin-engine, propeller-driven aircraft fuselage. The sound source was a pneumatic-driver, with attached horn to simulate propeller noise distribution, powered by a white noise signal. Treatments included a double-wall, production-line treatment and various fiberglass and lead-vinyl treatments. Insertion losses, space-averaged across six interior microphone positions, were used to evaluate the treatments. In addition, the effects of sound source angle and ambient temperature on interior sound pressure level are presented. The sound source angle is shown to have a significant effect on one-third octave band localized sound pressure level. While changes in ambient temperature are shown to have little effect on one-third octave band localized sound pressure level, the change in narrowband localized sound pressure level may be dramatic.

  8. Effect of noise reducing components on nose landing gear stability for a mid-size aircraft coupled with vortex shedding and freeplay

    Science.gov (United States)

    Eret, Petr; Kennedy, John; Bennett, Gareth J.

    2015-10-01

    In the pursuit of quieter aircraft, significant effort has been dedicated to airframe noise identification and reduction. The landing gear is one of the main sources of airframe noise on approach. The addition of noise abatement technologies such as fairings or wheel hub caps is usually considered to be the simplest solution to reduce this noise. After touchdown, noise abatement components can potentially affect the inherently nonlinear and dynamically complex behaviour (shimmy) of landing gear. Moreover, fairings can influence the aerodynamic load on the system and interact with the mechanical freeplay in the torque link. This paper presents a numerical study of nose landing gear stability for a mid-size aircraft with low noise solutions, which are modelled by an increase of the relevant model structural parameters to address a hypothetical effect of additional fairings and wheel hub caps. The study shows that the wheel hub caps are not a threat to stability. A fairing has a destabilising effect due to the increased moment of inertia of the strut and a stabilising effect due to the increased torsional stiffness of the strut. As the torsional stiffness is dependent on the method of attachment, in situations where the fairing increases the torsional inertia with little increase to the torsional stiffness, a net destabilising effect can result. Alternatively, it is possible that for the case that if the fairing were to increase equally both the torsional stiffness and the moment of inertia of the strut, then their effects could be mutually negated. However, it has been found here that for small and simple fairings, typical of current landing gear noise abatement design, their implementation will not affect the dynamics and stability of the system in an operational range (Fz ≤ 50 000 N, V ≤ 100 m/s). This generalisation is strictly dependent on size and installation methods. The aerodynamic load, which would be influenced by the presence of fairings, was modelled

  9. 飞机起落架气动噪声的数值计算方法%Numerical Computational Method for Predicting Aircraft Landing Gear Noise

    Institute of Scientific and Technical Information of China (English)

    宁方立; 马尧; 王善景; 郭琪磊; 黄文超

    2013-01-01

    我国目前正在自主研制民航大客机,噪声水平是其能否取得适航证的关键因素之一.在飞机着陆过程中,起落架噪声在飞机总噪声中已占据主体地位.基于试验数据,提出一种飞机起落架气动噪声的新型数值计算方法.该方法将起落架结构分解为圆柱体、机轮等基本部件.根据Ffowcs Williams-Hawkings方程,对每类基本部件提出对应的噪声预测方法.由这些基本部件组装成起落架,进而计算出起落架总体辐射噪声.该方法考虑多机轮存在情况,提出新型机轮模型,从而解决现有数值计算方法机轮模型过于简单,并导致不正确计算结果的问题;提出基于圆柱体方向仿真数据的圆柱体部件指向性确定方案,解决现有数值计算方法噪声辐射指向性错误的问题.另外,该方法能够确定出对起落架总体辐射噪声贡献最大的基本部件,为低噪声起落架设计提供依据.%The civil aviation big plane is being developed in China. The noise level is a key factor to decide the airworthiness certificate ratification. On landing, the landing gear noise has become the major noise contributor for the total aircraft noise. Based on experimental data, a new numerical computational method for predicting aircraft landing gear noise is developed. In this method, the landing gear is divided into main parts, including cylinders and wheels. Then noise prediction models for every kind of parts are proposed by using the Ffowcs Williams-Hawkings equation. Finally, summed the noise of the different parts, the the total radiation noise of the landing gear can be obtained. The noise of landing gears with several wheels can be calculated by the new wheel model in the method, so the incorrect results by the simple wheel model in existing numerical methods can also be avoided. Based on the simulation data of the cylindrical directivity, the new model for calculating the directivity is proposed in the method. The

  10. ARJ客机过顶飞行过程噪声的实验研究%ARJ Aircraft Noise Measurement from Fly-over Test

    Institute of Scientific and Technical Information of China (English)

    陈涛; 侯宏; 陈志菲; 赵江楠

    2012-01-01

    ARJ aircraft noise sources were obtained from fly-over measurements. In order to distinguish different noise sources, array signal processing technology was used, and multi-arms spiral array was designed. The result shows that the main noise sources are aero-engine,landing gear,flaps and the back of empennages and the main sources are different with the different frequencies. These can provide the support for noise reduction.%对ARJ客机过顶的噪声源进行了现场实验分析.为了将飞机不同噪声源分开,利用了阵列信号处理技术,设计了多臂螺旋阵.实验发现:ARJ飞机的噪声源主要分布在发动机、起落架、襟翼、尾翼后部等位置,不同频率下,主要噪声源的组成不同,为飞机降噪工作提供了支持.

  11. Measurements of V/STOL aircraft noise mechanisms using pressure cross-correlation techniques in a reverberant wind tunnel

    Science.gov (United States)

    Meecham, W. C.; Hurdle, P. M.

    1974-01-01

    A 3.8 cm. model jet was operated in a wind tunnel with cross-flow in order to determine the effect on jet noise radiated characteristics. A method was developed for the determination of noise radiating characteristics of sources within reverberant wind tunnels; cross-correlation measurements were used. The averaging time in the cross-correlation is determined by the amount of background noise within the wind tunnel. It was found that cross-flow increases the radiated noise by 10 db. There was some indication of downstream radiation exceeding the sideline radiation.

  12. Low Noise Aircraft Selection Based on Improved Grey Relational Analysis of B-Mode%基于改进灰色B型关联度的低噪声飞机选型

    Institute of Scientific and Technical Information of China (English)

    李东亚; 胡荣; 江超; 战绪仁

    2015-01-01

    为有效缓解飞机噪声的影响,选择出噪声值更小的机型,针对国内某机场噪声监测数据特点,选用兼具相近性与相似性的灰色B型关联分析法对该机场一个月内同一航班六种机型噪声监测数据进行分析.根据研究问题需要,设计无量纲化处理方法,优化噪声监测数据权重,改进灰色B型关联度方法,计算各机型噪声数据与最优数据的关联度,优选出满足条件的低噪声机型.结果表明,改进后灰色B型关联度方法适用于低噪声飞机选型问题,分析结果符合实际,其中B733机型最能满足该机场低噪声的条件.%To alleviate the influence of aircraft noise effectively and choose the lower noise aircraft types, the noise monitoring data of six kinds of aircrafts for the same flight at a domestic airport were analyzed using the grey relational analysis of B-mode which has both proximity and similarity. In this analysis, a dimensionless processing method was designed to optimize the weight of the noise monitoring data and improve the grey relational analysis of B-mode. The correlations between the aircraft noise data of different type of aircrafts and the optimal noise data were calculated and the low noise aircraft type was selected. The results show that the improved grey relational analysis of B-mode is suitable for the selection of low noise aircraft, and the analysis results are consistent with the actual data. In addition, the B733 aircraft type is the best in satisfying the condition of low noise at the airport.

  13. Analysis of Acoustic Environment Index of Aircraft Noise and Planning and Selection of the Location of Airport%机场飞机噪声声环境指标分析及规划选址分析

    Institute of Scientific and Technical Information of China (English)

    田瑞丽; 李洪波; 冯海波; 马丽霞

    2014-01-01

    The location of different sizes of airport is different, and the impact degree of the aircraft noise is different. Rational utilization of the land surrounding the airport can reduce the impact of aircraft noise. This article lists acoustic environmental indicators of aircraft noise of the different scale domestic airport, and analyzes the land use planning around the airport.%不同规模的机场,选址不同,飞机噪声影响程度不同,对机场周边土地进行合理利用,以降低飞机噪声影响,本文列出了国内不同规模机场飞机噪声的声环境指标,并对机场周围土地利用规划进行了分析。

  14. A Study into Impacts of Local Sound's Environment from Aircraft Noise Pollution%机场飞机噪声对区域声环境影响的研究

    Institute of Scientific and Technical Information of China (English)

    韩宝坤

    2011-01-01

    根据机场飞机噪声对周围敏感区域影响的状况,结合实测数据和环评预测结果,就飞机噪声对机场周围敏感区域的影响进行了分析研究,并提出了较为合理的飞机噪声控制建议参考。%The impacts on the local sound's environment by aircraft noise have been investigated, based on combined data sources from current sound environment measurement and estimates from environmental impacts projection, with special emphasis and considerations allowed to areas susceptible to aircraft noise disruption. Suggestions thus been put forward for further aircraft noise regulation.

  15. Exposure-effect relations between aircraft and road traffic noise exposure at school and reading comprehension: the RANCH project.

    NARCIS (Netherlands)

    Clark, Charlotte; Martin, Rocio; Kempen, Elise van; Alfred, Tamuno; Head, Jenny; Davies, Hugh W; Haines, Mary M; Lopez Barrio, Isabel; Matheson, Mark; Stansfeld, Stephen A

    2006-01-01

    Transport noise is an increasingly prominent feature of the urban environment, making noise pollution an important environmental public health issue. This paper reports on the 2001-2003 RANCH project, the first cross-national epidemiologic study known to examine exposure-effect relations between air

  16. Aircraft noise-induced annoyance in the vicinity of Cologne/Bonn Airport - The examination of short-term and long-term annoyance as well as their major determinants

    OpenAIRE

    BARTELS, SUSANNE

    2014-01-01

    In the light of a continuously growing air traffic and a presumably resulting impairment of the quality of life of airport residents, the present doctoral thesis aims at the extensive investi-gation and description of short-term and long-term annoyance induced by aircraft noise in the vicinity of Cologne/Bonn Airport, Germany. This thesis was written in the framework of the European project COSMA (Community Oriented Solutions to Minimise Aircraft noise annoyance). A telephone study with 1,262...

  17. Application of Integral Correction Method in the Aircraft Noise Certification%积分修正方法在飞机噪声合格审定中的应用

    Institute of Scientific and Technical Information of China (English)

    闫国华; 周利敏

    2013-01-01

    In the process of aircraft noise certification, there are differences between the actual flight test conditions of aircraft and its required reference conditions of noise certification, based on corresponding geometric conditions of flight test and the laws of noise propagation, Integral correction method of calculating Effective Perceived Noise Level (EPNL) was established;Taking the aircraft CRJ 700 as example, the equivalence of Integral correction method and the standard method provided in ICAO Annex 16 was proved, which is significant to the Noise Certification of aircraft ARJ 21-700.%在飞机噪声合格审定过程中,实际飞行试验条件与噪声合格审定规范中要求的基准条件存在差异,依据飞行试验中相应的几何条件和噪声传播的规律,建立计算有效感觉噪声级的积分修正方法;以CRJ 700飞机为例,证明积分修正方法与国际民航组织在附件16中规定的标准方法等效,对ARJ 21-700飞机噪声合格审定具有重要意义。

  18. 基于白云国际机场规划对飞机噪声影响的分析探讨%Analysis and Discussion the Impact of Baiyun International Airport Planning on Aircraft Noise

    Institute of Scientific and Technical Information of China (English)

    马磊

    2014-01-01

    本文主要基于白云国际机场规划,研究分析了飞机噪声对周围环境的影响。通过借助计算机软件 INM7.0,拟合了白云机场的飞机噪声等值线图,并结合噪声等值线图和城市规划,对相应的降噪措施进行了分析和探讨。%This paper, mainly based on Baiyun International Airport Planning, studied and analyzed the influence of aircraft noise on the surrounding environment. By using the computer software INM7.0, the author drawn the contour map of the aircraft noise from Baiyun airport, and combined With the noise contour map and city planning, analyzed and discussed the relevant noise reduction measures.

  19. B737NG飞机异响的几种情形和排故思路%Several Cases of B737NG Aircraft Noise and Troubleshooting Ideas

    Institute of Scientific and Technical Information of China (English)

    张坤锋

    2015-01-01

    It will become a troublesome thing for the ground personnel when there are abnormal noises of aircraft recorded in the technical logbook or described orally, especially when the unit cannot accurately describe the types and sources of the noises, the personnel need to judge many segments repeatedly, and the faults can be eliminated even by observation with the plane of ground personnel. This paper analyzes the type, sources and stages of the cockpit noises, hoping to provide references for troubleshooting. The abnormal noises in this paper refer to the sound that the pilots heard during the phases of taxiing, taking off, climbing and cruise.%当机组在技术记录本上记录或口头描述听到飞机异响时,经常会成为令地面人员很头疼的一件事情,特别是机组无法准确描述声音的类型和来源时,需要经过多个航段的反复判断,甚至是地面人员进行跟机观察,才能最终排除。本文从驾驶舱异响的类型和声音来源,发生的阶段进行分析,以期能为故障的排除提供参考。本文所指异响是指飞行员在飞机滑行、起飞、爬升、巡航等阶段听到的异常声音。

  20. Design and Simulation of Adaptive Active Noise Control System for Aircraft Helmet%飞行头盔主动噪声控制系统的设计及仿真研究

    Institute of Scientific and Technical Information of China (English)

    唐红; 王明皓; 吴凤霞

    2011-01-01

    Aiming at solving low frequency noise existing in cockpit,a design for adaptive active noise control system of aircraft helmet is proposed. Based on it,the filtered-XLMS algoritbm is simulated and analysed using MATLAB.The result shows that the effect of reducing aircraft noise on low frequency is very satisfactory with the scheme.%针对飞机驾驶舱内存在着大量的低频噪声,提出一种应用于飞行员头盔的自适应有源噪声控制系统设计方案,并在此基础上,利用MATLAB对FXLMS算法进行了仿真和性能分析。结果表明,此方案对飞机噪声低频段具有很好的降噪效果。

  1. Review of measured vibration and noise environments experienced by passengers in aircraft and in ground transportation systems

    Science.gov (United States)

    Stephens, D. G.

    1975-01-01

    Measured vibration and interior noise data are presented for a number of air and surface vehicles. Consideration is given to the importance of direction effects; of vehicle operations such as take-off, cruise, and landing; and of measurement location on the level and frequency of the measurements. Various physical measurement units or descriptors are used to quantify and compare the data. Results suggest the range of vibration and noise associated with a particular mode of transportation and illustrate the comparative levels in terms of each of the descriptors. Collectively, the results form a data base which may be useful in assessing the ride of existing or future systems relative to vehicles in current operation.

  2. Simulation of Noise-Cancelling in the Cockpit of an Aircraft Using Two-Rate Hybrid Neural Network

    Directory of Open Access Journals (Sweden)

    ASTROV, I.

    2007-11-01

    Full Text Available This paper presents the two-rate hybrid neural network (TRHNN for processing of noisy signal. The received TRHNN consists of "fast" ADAptive LInear NEuron neural network (FADALINENN and "slow" radial basis neural network (SRBNN. The illustrative design example - noise-cancelling of noisy pilot's voice pattern - was carried out using the TRHNN. The received TRHNN has high speed of signal processing. This example demonstrates that the proposed TRHNN is capable not only to recognize the pilot's voice in the noisy voice pattern, but also to restore the pilot's voice. The simulation results with use the software package Simulink show the computing procedure and applicability of the TRHNNs for fast-acting signal processing and analysis in real-time flight conditions.

  3. ARJ客机进场飞行过程的起落架噪声的实验研究%ARJ aircraft landing gear noise characteristics detected by fly-over measurements

    Institute of Scientific and Technical Information of China (English)

    陈涛; 侯宏; 陈志菲

    2012-01-01

    对ARJ客机降落阶段的起落架噪声进行了现场测量分析,为了将起落架噪声源与其他噪声源分开,利用了阵列信号处理技术,实验发现:ARJ飞机起落架噪声主要集中在900 Hz以下,且前、主起落架均存在强单音噪声,对起落架噪声可能的声源来源进行了分析,为起落架降噪设计提供了支持.%ARJ aircraft landing gear noise spectra and contours were obtained by fly-over measurements. In order to distinguish the source of landing gear from other noise sources, array signal processing technology was used. The result shows; ARJ aircraft landing gear noise is of broadband spectrum with some single tones, whose energys are mainly concentrated at 900 Hz below. The possible noise sources were analyzed, which benefits the design of landing gear noise reducing.

  4. Auralization of novel aircraft configurations

    OpenAIRE

    Arntzen, M.; Bertsch, E.L.; Simons, D.G.

    2015-01-01

    A joint initiative of NLR, DLR, and TU Delft has been initiated to streamline the process of generating audible impressions of novel aircraft configurations. The integrated approach adds to the value of the individual tools and allows predicting the sound of future aircraft before they actually fly. Hence, an existing process for the aircraft design and system noise prediction at DLR has been upgraded to generate the required input data for an aircraft auralization framework developed by NLR ...

  5. 传声器阵列反方法及其对飞机噪声源识别%Inverse Method of Microphone Array and Aircraft Noise Source Identification

    Institute of Scientific and Technical Information of China (English)

    马军会; 乔渭阳; 谭洪川; 赵磊

    2011-01-01

    为了完善飞机气动噪声源识别测量技术,并认识当代大型客机气动噪声源的基本特征,改进噪声源识别的大型平面传声器阵列.该阵列由104个传声器组成,104个传声器在平面中的位置通过计算机优化设计的方法确定.并用数值模拟的方法检验平面传声器阵列的频谱特性.应用此阵列在西安咸阳国际机场对近20个架次的进场着陆飞机噪声源进行试验测量.通过实验验证传声器阵列技术和传声器阵列数据处理软件.%In order to develop and improve the technique of identification and measurement of aircraft noise source, and to understand the essential properties of the noise source deeply, a large planar microphone array for the landing process of large civil aircraft has been developed.This plane array is composed by 104 microphones whose positions in the plane are determined by the computer aided optimization design.Meanwhile, the spectrum characteristics of the array have been tested by means of numerical simulation.The plane array has been used to measure the noise sources of 20 landing aircrafts in the Xi’an Xianyang International Airport.In the experiment, a noise source identification and measurement system for large civil aircraft has been built and developed, and the microphone array technique and its data processing software also have been verified.

  6. Aeroacoustic Prediction and Noise Reduction

    OpenAIRE

    Delfs, Jan Werner

    2011-01-01

    An overview is given about aeroacoustic prediction and noise reduction technology from the field of aircraft noise. The simulation philosophy of the prediction methods is related to real world application, i.e. high Reynolds number flows, typical for aircraft. Noise reduction concepts are studied in two ways i) through a silent by design approach and b) by add-on treatments for existing aircraft components. Challenges are identified for future research.

  7. 航空噪声与运行监测系统在首都机场的应用%The Application of Aircraft Noise and Operation Monitoring System ( ANOMS) in Beijing Capital International Airport

    Institute of Scientific and Technical Information of China (English)

    段钢; 姜文娟

    2015-01-01

    With the rapid growth of the passenger throughput and flight volume ,the influence of air craft noise has become increasingly serious around the airport .As the first and the only one airport having ANOMS in China ,the airport is strength-ening the use of ANOMS .On the basis of the monitoring data within these years ,the system can promote the work of noise abatement through several measures ,such as the calculating of noise contour ,analysis of the priority runway ,recognition of the noise sensitive area ,eli mination of the old aircraft ,and monitoring of the illegal aircraft ,etc.%指出了随着旅客吞吐量和航班量的快速增长,首都机场周边的航空噪声影响日益严重,通过积累多年的监测数据,实现了等值线图的绘制、优先跑道分析、噪声敏感区识别、老旧机型淘汰、违规航班监测等功能,以全方位推动航空噪声削减工作.

  8. 某型飞机起落架结构件气动噪声仿真与试验研究%Simulation and Experiment Study on Aero-acoustic Noise of an Aircraft's Landing Gear Structure

    Institute of Scientific and Technical Information of China (English)

    许远; 龙双丽; 薛彩军; 聂宏

    2012-01-01

    起落架噪声是飞机着陆阶段噪声的主要组成部分。以某型飞机前起落架为研究对象,通过分离涡模拟方法对其支柱及扭力臂结构件简化模型的周围流场进行非定常计算,利用Fw—H方程积分法对各部件表面产生的声场进行求解,分析缓冲支柱及扭力臂结构件气动噪声的产生机制、声源特性。对该飞机起落架支柱及扭力臂结构件进行声学风洞试验,通过麦克风对噪声的测量获得结构件噪声频谱特性。仿真及试验结果均表明:支柱及扭力臂结构件气动噪声包含支柱和扭力臂引起的钝体扰流噪声和两者相对位置引起的干扰噪声,支柱噪声对总噪声的贡献大于扭力臂噪声,噪声辐射特性具有偶极子声源的辐射特性。%Aircrafts' noise produced by landing gears is the main noise in the landing stage. Simulation analysis using Detached Eddy Simulation is performed to simulate the flow field around the simplified structure including the strut and torque link of an aircraft's nose landing gear. The acoustic field radiated from different model parts and total model are calculated via FW-H equation. The noise mechanism and acoustic characteristics of the noise from the structure are analyzed. Wind tunnel test is performed to measure the noise spectra of the structure by microphones. The simulation and experiment results show that the noise of the assembly of strut and torque link include bluff body and interaction noise. Noise from the strut has greater contribution to total noise than that from the torque link. The whole model noise radiation direetivity is similar to the dipole characteristics.

  9. Noise synthesis for the Virtual Community Noise Simulator

    OpenAIRE

    Arntzen, M.

    2013-01-01

    Aircraft noise imposes restrictions on possible growth of airports. Noise mitigation measures can be based long-term predictive models but would benefit from high-fidelity simulation of the audible effects. To this end the NLR uses its Virtual Community Noise Simulator (VCNS). Several modelling steps and an application will be demonstrated in this article as to show the promising future of aircraft noise synthesis.

  10. Discussion on Aircraft Noise Evaluation Parameters in Airport and Their Limited Values%机场飞机噪声评价量及其限值的探讨

    Institute of Scientific and Technical Information of China (English)

    肖慧慧; 王超; 徐肖豪

    2011-01-01

    The shortcomings of current airport noise evaluation parameters, which include weighted equivalent continuous perceived noise level (WECPNL), are analyzed.According to the above analysis, equivalent sound level Leq and sound exposure level (SEL) are proposed as the new airport noise evaluation parameters.Annoyance and sleep disturbance caused by the aircraft noise are analyzed in detail.And the limitation values of corresponding noise evaluation parameters are suggested.%对计权等效连续感觉噪声级WECPNL作为机场噪声评价量的不足进行分析,并以此为基础提出采用等效声级Leq和声暴露级SEL两个参量作为机场噪声的评价量.从飞机噪声引起的主观烦恼度和对睡眠的干扰两个方面进行深入分析,并提出相应评价量的限制标准建议值.

  11. The Effects of Aircraft Noise on the Auditory Language Processing Abilities of English First Language Primary School Learners in Durban, South Africa

    Science.gov (United States)

    Hollander, Cara; de Andrade, Victor Manuel

    2014-01-01

    Schools located near to airports are exposed to high levels of noise which can cause cognitive, health, and hearing problems. Therefore, this study sought to explore whether this noise may cause auditory language processing (ALP) problems in primary school learners. Sixty-one children attending schools exposed to high levels of noise were matched…

  12. 民用飞机噪声合格审定的切入飞行试验方法%Intercept Flight Test Method of Civil Aircraft Noise Certification

    Institute of Scientific and Technical Information of China (English)

    闫国华; 周利敏

    2014-01-01

    Civil aircraft noise certification usually requires repeated flight tests, which is costly and time-consuming. This paper proposes a complete intercept flight test method to reduce the costs and shorten the certification period. The intercept flight procedures of take-off and approach noise measurement test were established based on the establishment principle of equivalent aircraft noise certification procedures approved by International Civil Aviation Organization. The method for determining 10 dB-down period is summarized with a specific type of jet as example. The intercept flight test method is of high application value for the noise certification of future ARJ21-700 derivative types and C919.%针对民用飞机噪声合格审定中重复多次进行相关飞行试验造成的成本高、耗时长问题,为进一步降低民用飞机噪声合格审定成本、缩短审定周期,基于国际民航组织规定的飞机噪声合格审定等效程序建立原则,通过对飞机起飞和进场的噪声测量试验建立飞机噪声合格审定中的切入飞行程序,从而构建完整的切入飞行试验方法。以某型喷气式飞机为例,概述了10 dB降区间的确定方法;设计了切入飞行试验方法,对于未来ARJ21-700的衍生机型及C919的噪声合格审定具有重要的工程应用价值。

  13. Research on Airport's Surrounding Residents'Subjective Annoyance to Aircraft Noise%机场周边居民对飞机噪声反应的主观烦恼度研究

    Institute of Scientific and Technical Information of China (English)

    尹建坤; 田瑞丽; 李洪波; 刘孝峰; 赵仁兴

    2014-01-01

    结合国外对飞机烦恼度的研究,提出了对飞机噪声和烦恼度反应关系的调查方法。通过几个有代表性机场烦恼度调查的人数和声级范围的比较,给出了高烦恼率的计算方法,并分析了高烦恼率和声级相关分析。并给出了数字化等级量表的高烦恼率统计分析方法和文字性描述等级量表的高烦恼率统计分析方法。通过对几个机场烦恼度调查,给出了不同机场周围人群对飞机噪声反应的比较。经过国内外烦恼度调查结果的曲线比较,给出了应该选取的评价量。并通过主观烦恼度阈值的计算得到了高烦恼率统计数值,提出了我国飞机噪声评价标准的建议。%Based on the researches of abroad aircraft annoyance ,this article provides a research method which can find out the relationship between aircraft noise and annoyance .Through comparison of several represent-ative airport annoyance investigation's number of people and sound level range ,high annoyance rate calcula-tion method is found out and correlation analysis .of high annoyance and sound level is done .Digital rating scale and text description rating scale's high annoyance rate statistic analysis method is also provided . Through several airports'annoyance investigation ,the article gives a comparison of different airports sur-rounding residents'reaction to aircraft noise .The comparison of domestic and overseas annoyance investiga-tion results'curves provides the evalation standard that should be selected .The high annoyance statistic is calculated through the subjective annoyance's threshold value ,w hich offers some suggestions to evaluation criteria of aircraft noise .

  14. 14 CFR 36.801 - Noise measurement.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Noise measurement. 36.801 Section 36.801 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION Helicopters § 36.801 Noise measurement. For primary,...

  15. Calculation Method and Analysis of Aircraft Noise in Atmospheric Attenuation%飞机噪声在大气中衰减的计算方法及分析

    Institute of Scientific and Technical Information of China (English)

    闫国华; 张子健

    2015-01-01

    In this paper, the basic principle of sound absorption is analyzed, and the existing methods for calculating the at-mospheric acoustic absorption are studied. The new calculation method of atmospheric absorption is used to calculate the atten-uation of the aircraft noise which is produced in operation process, and the factors that would affect the attenuation are ana-lyzed. Then the results are compared with the existing ARP 866A standards in the calculation of aircraft noise certification lev-els. By the comparison, a conclusion can be received that the calculation method of acoustic attenuation adopted in this paper is more accurate than the ARP 866A methods. The new method will provide a great help for the governance of civil aviation noise pollution.%分析声吸收的基本原理,研究现有的大气声吸收的计算方法,运用新的大气声吸收的计算方法,计算民航客机在运营过程中产生的噪声在大气中的衰减量,并对影响其衰减的因素进行分析,然后将其结果与标准中提出的大气声衰减的方法进行比较。通过对比可得出,本文所采用的方法对声衰减的计算更加准确。

  16. Noise sensitivity and reactions to noise and other environmental conditions

    NARCIS (Netherlands)

    Miedema, H.M.E.; Vos, H.

    2003-01-01

    This article integrates findings from the literature and new results regarding noise sensitivity. The new results are based on analyses of 28 combined datasets (N=23 038), and separate analyses of a large aircraft noise study (N=10939). Three topics regarding noise sensitivity are discussed, namely,

  17. Measurements techniques for transportation noise

    Energy Technology Data Exchange (ETDEWEB)

    Brambilla, G

    2001-07-01

    The noise from transport systems (roads, railways and aircraft) are increasing more and more both in space and in time and, therefore, they are still the major factor responsible for environmental noise pollution. The population exposed to transport noise is also increasing, and the corresponding health effects on people (i.e. annoyance and sleep disturbance) become more severe. Due to this current situation international and national legislation has been issued and implemented to reduce the harmful effects of such noise. This paper describes the techniques prescribed by recent Italian legislation to measure road, railway and aircraft noise. (author)

  18. Development of Adjustable Absorption Acoustic Liner for Active Fan Noise Control

    OpenAIRE

    小林, 紘; Kobayashi, Hiroshi

    2003-01-01

    Due to strong demands from communities adjacent to airports for the suppression aircraft noise, a new aircraft noise certification standard as set out in ICAO Chapter 4 was formulated and will come into effect in 2006 for new subsonic aircrafts. Currently, not only aircraft noise affecting communities surrounding airports but also aircraft noise at night, during climb and while cruising have become serious issues. In order to solve these issues, at NAL, new techniques and systems have been de...

  19. Sensitivity analysis of airport noise using computer simulation

    Directory of Open Access Journals (Sweden)

    Flavio Maldonado Bentes

    2011-09-01

    Full Text Available This paper presents the method to analyze the sensitivity of airport noise using computer simulation with the aid of Integrated Noise Model 7.0. The technique serves to support the selection of alternatives to better control aircraft noise, since it helps identify which areas of the noise curves experienced greater variation from changes in aircraft movements at a particular airport.

  20. Identification and Reduction of Turbomachinery Noise Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Communities near airports are often exposed to high noise levels due to low flying aircraft in the takeoff and landing phases of flight. Propulsion source noise is...

  1. Aeroacoustics of Flight Vehicles: Theory and Practice. Volume 2: Noise Control

    Science.gov (United States)

    Hubbard, Harvey H. (Editor)

    1991-01-01

    Flight vehicles and the underlying concepts of noise generation, noise propagation, noise prediction, and noise control are studied. This volume includes those chapters that relate to flight vehicle noise control and operations: human response to aircraft noise; atmospheric propagation; theoretical models for duct acoustic propagation and radiation; design and performance of duct acoustic treatment; jet noise suppression; interior noise; flyover noise measurement and prediction; and quiet aircraft design and operational characteristics.

  2. Supersonic Jet Noise: Main Sources and Reduction Methodologies

    OpenAIRE

    Mohammadreza Azimi; Fathollah Ommi

    2014-01-01

    The large velocity ratio and the presence of Shocks in the exhaust plume from low bypass engines or supersonic jetliners cause jet noise to be dominant component of overall aircraft noise, and therefore is an important issue in design of the next generation of civil supersonic transport. Jet noise reduction technology also has application in the design of highperformance tactical aircraft. Jet noise is of particular concern on aircraft carriers where it is necessary for deck crew to ...

  3. 单个飞机噪声事件最小顶点覆盖模型的几场噪声监测点分布方法%Locating of Airport Noise Monitoring Points Based on Minimum Vertex Cover Model of Single Aircraft Noise Event

    Institute of Scientific and Technical Information of China (English)

    丁文婷; 徐涛; 杨国庆

    2012-01-01

    为监测和分析中小型机场附近噪声污染状况,提出一种基于单个飞机噪声事件最小顶点覆盖模型的机场噪声监测点分布方法.该方法以大量网格点作为候选监测点,形成顶点集合,利用INM噪声预测软件计算各顶点在每个噪声事件发生时的噪声值,根据单个飞机噪声事件的限值确定各项点监测到的噪声事件,从而建立最小顶点覆盖模型,然后采用改进的贪心算法求得近似最优解,使得顶点能覆盖所有噪声事件并且个数最少,实验证明改进的贪心算法比传统的贪心算法得到的解更优,需要的监测点更少.%In order to monitor and analyze the noise pollution around a small and medium scale airport, a locating method of airport noise monitoring points based on minimum vertex cover model of single aircraft noise event was proposed. First of all, a large number of grid points constituting the vertex set were assumed as candidate monitoring points. The INM noise prediction software was used to calculate the noise values of these vertices when each event happened. According to the noise threshold of single event, one could determine whether a vertex monitors the event or not. Then the minimum vertex cover model could be established. After that, the minimum number of vertices which cover all noise events could be obtained by employing the improved greedy algorithm. Experimental results show that the improved greedy algorithm is better than traditional greedy algorithm. It needs less monitoring points for covering all noise events.

  4. Research on aircraft noise contour drawing algorithm%飞机噪声等值线绘制算法的研究

    Institute of Scientific and Technical Information of China (English)

    高婷; 王迪

    2012-01-01

    For airport noise characteristics and distribution, a tracking algorithm of airport noise contours based on path grid is presented. By constructing effective grid vertex and path grid, contour tracking process can determine the only next equivalent points, and quickly generate a contour map, then smooth contour according to its own characteristics. Finally, in order to check the influence of noise of different regions, it is necessary to fill the contour with different colors.%针对机场噪声的特征及分布特点,提出了一种基于路径栅格的机场噪声等值线追踪算法。通过构造有效网格、建立具有顶点和的路径栅格,在等值线追踪过程中唯一确定下一个等值点,能够快速生成等值线图,然后根据自身特点对等值线进行光滑,最后,为了方便查看不同区域的噪声影响情况,需要对等值线用不同的颜色进行填充处理。

  5. Military aviation noise:noise-induced hearing impairment and noise protection

    OpenAIRE

    Kuronen, P. (Pentti)

    2004-01-01

    Abstract This research on military aviation noise was conducted because the personnel working with military aircraft were concerned about noise induced hearing damage. In addition, comprehensive data on hearing impairments and occupational exposure of military pilots in the Finnish Air Force was not available. Moreover, data on the effects of overflight noise of military jets was necessary for the evaluation of noise induced hearing deteriorations of members of the ...

  6. Core Noise - Increasing Importance

    Science.gov (United States)

    Hultgren, Lennart S.

    2011-01-01

    This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system-level noise metrics for the 2015, 2020, and 2025 timeframes; turbofan design trends and their aeroacoustic implications; the emerging importance of core noise and its relevance to the SFW Reduced-Perceived-Noise Technical Challenge; and the current research activities in the core-noise area, with additional details given about the development of a high-fidelity combustor-noise prediction capability as well as activities supporting the development of improved reduced-order, physics-based models for combustor-noise prediction. The need for benchmark data for validation of high-fidelity and modeling work and the value of a potential future diagnostic facility for testing of core-noise-reduction concepts are indicated. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The SFW Reduced-Perceived-Noise Technical Challenge aims to develop concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. This reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic. Noise generated in the jet engine core, by sources such as the compressor, combustor, and turbine, can be a significant contribution to the overall noise signature at low-power conditions, typical of approach flight. At high engine power during takeoff, jet and fan noise have traditionally dominated over core noise. However, current design trends and expected technological advances in engine-cycle design as well as noise-reduction methods are likely to reduce non-core noise even at engine-power points higher than approach. In addition, future low-emission combustor

  7. Amphibious Aircraft

    Data.gov (United States)

    National Aeronautics and Space Administration — A brief self composed research article on Amphibious Aircrafts discussing their use, origin and modern day applications along with their advantages and...

  8. Noise suppression by noise

    OpenAIRE

    Vilar, J. M. G.; Rubí Capaceti, José Miguel

    2001-01-01

    We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail.

  9. ARJ21客机降落阶段起落架噪声试验研究%Landing gear noise identification in the ARJ21 aircraft landing process

    Institute of Scientific and Technical Information of China (English)

    陈涛; 侯宏; 陈志菲; 赵江楠; 姜成坤

    2013-01-01

    The acoustic flyover tests are performed for an ARJ21 aircraft with the objective to measure the landing gear noise.The algorithms of improved frequency domain Conventional Beamforming (CBF) and Deconvolution Approach for the Mapping of Acoustic Sources (DAMAS) are used.It is demonstrated that DAMAS has better capability of noise source identification.In order to improve the utilization of the microphones,a multi-arms spiral array is designed and applied to the measurement.The doppler effect is removed by using linear interpolation.According to the distribution of the main landing gear and nose landing gear,the identification area is divided into two parts and is analyzed from 140 Hz to 800 Hz on 1/3 octave band.It is shown that the main landing gear is the main noise source above 250 Hz.Especially,it is the only strong noise source in 1/3 octave band of 500 Hz centre frequency,whereas the nose landing gear is the main noise source in 1/3 octave band of 630 Hz centre frequency.By this test,the noise characteristics of the main landing gear and nose landing gear are investigated in different frequency range which is significant to landing gear noise control engineering.%为了测量ARJ21客机的起落架噪声,在飞行现场分别采用改进的频域波束形成和解卷积算法对降落阶段的起落架噪声进行了测量.通过比较两种算法发现,解卷积算法比改进的频域波束形成算法具有更好的声源识别能力.为了提高传声器的利用率,设计了多臂螺旋阵,并且利用线性插值消除了多普勒效应.根据主起落架和前起落架的分布位置不同,将声源识别区域划分为两部分,在140~800 Hz范围内对不同频段的1/3倍频程的起落架噪声进行了测量.结果发现:在250 Hz以上频段,主起落架为主要噪声源,且在中心频率500 Hz的1/3倍频程内为唯一强声源;前起落架在中心频率630 Hz的1/3倍频程内为主要噪声源.通过试验得到了主起落架和前

  10. Aircraft Design

    Science.gov (United States)

    Bowers, Albion H. (Inventor); Uden, Edward (Inventor)

    2016-01-01

    The present invention is an aircraft wing design that creates a bell shaped span load, which results in a negative induced drag (induced thrust) on the outer portion of the wing; such a design obviates the need for rudder control of an aircraft.

  11. Noise and health of children

    NARCIS (Netherlands)

    Passchier, W.

    2000-01-01

    The world of the child is becoming noisier and noisier. Compared to the mid-fifties environ-mental noise levels (sources such as road traffic, aircraft) increased substantially, causing higher noise levels during day- and night-time at home, at school and during out- and indoors leisure time activit

  12. Perforated fairings for landing gear noise control

    OpenAIRE

    Boorsma, K.; Zhang, X; Molin, N.

    2008-01-01

    Landing gears of commercial aircraft make an important contribution to total aircraft noise in the approach configuration. Using fairings to shield components from high speed impingement reduces noise. Furthermore, perforating these fairings has been confirmed by flight tests to further enable noise reduction. Following a more fundamental study on the application of perforated fairings, a study has been performed to investigate and optimize the benefits of bleeding air through landing gear fa...

  13. Numerical investigation of landing gear noise

    OpenAIRE

    Liu, Wen

    2011-01-01

    Noise generated by aircraft landing gears is a major contributor to the overall airframe noise of a commercial aircraft during landing approach. Because of the complex geometry of landing gears, the prediction of landing gear noise has been very difficult and currently relies on empirical tools, which have limited reliability and flexibility on the applications of unconventional gear architectures. The aim of this research is to develop an efficient and accurate numerical method to investigat...

  14. Application of acoustically tuned resonators for the improvement of sound insulation in aircraft

    NARCIS (Netherlands)

    Hannink, M.H.C.; Vlasma, J.P.; Wijnant, Y.H.; Boer, de A.

    2005-01-01

    One of the aims of the EU project FACE (Friendly Aircraft Cabin Environment) is to reduce aircraft interior noise. For modern aircraft flying at cruise conditions, the turbulent boundary layer is the main source for cabin noise. Normally, the turbulent boundary layer causes the trim panels to vibrat

  15. Impact of Advanced Propeller Technology on Aircraft/Mission Characteristics of Several General Aviation Aircraft

    Science.gov (United States)

    Keiter, I. D.

    1982-01-01

    Studies of several General Aviation aircraft indicated that the application of advanced technologies to General Aviation propellers can reduce fuel consumption in future aircraft by a significant amount. Propeller blade weight reductions achieved through the use of composites, propeller efficiency and noise improvements achieved through the use of advanced concepts and improved propeller analytical design methods result in aircraft with lower operating cost, acquisition cost and gross weight.

  16. 32 CFR 989.32 - Noise.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Noise. 989.32 Section 989.32 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ENVIRONMENTAL PROTECTION ENVIRONMENTAL IMPACT ANALYSIS PROCESS (EIAP) § 989.32 Noise. Aircraft noise data files used for analysis during EIAP will be submitted to HQ AFCEE for review...

  17. Experimental assessment of low noise landing gear component design

    OpenAIRE

    Dobrzynski, Werner; Chow, Leung Choi; Smith, Malcolm; Boillot, Antoine; Dereure, Olivier; Molin, Nicolas

    2009-01-01

    Landing gear related airframe noise is one of the dominant aircraft noise components at approach. It therefore is essential to particularly reduce landing gear noise. In the European SILENCER project, advanced low noise gears had been designed and tested at full scale. In the current European co-financed project TIMPAN (Technologies to IMProve Airframe Noise) still more advanced low noise design concepts were investigated and noise tested on a ¼ scaled main landing gear model in the German-Du...

  18. Analysis on occupational hearing loss of noise-exposed workers in an aircraft maintenance engineering company%某飞机维修工程公司噪声作业人员听力损伤分析

    Institute of Scientific and Technical Information of China (English)

    张君

    2013-01-01

    [Objective]To investigate the noise-exposed workers in an aircraft maintenance engineering company, to analyze their hearing impairment status, and put forward suggestions for prevention of occupational hearing loss and occupational noise deafness. [Methods] A total of 1 067 noise-exposed workers were recruited as noise group and 111 without noise exposure as control group. MM-622 pure tone audiometer by the zero-level correction was adopted for pure tone air conduction checks at 0.5, 1.0, 2.0, 3. 0, 4.0, 6.0 kHz on ears of workers. Assessment standards of hearing impairment: speech frequency at 0. 5, 1.0, 2.0 kHz in average >25dB, high-frequency at 3.0, 4.0, 6.0 kHz respectively ≥30 dB. [Results] A total of 1 067 workers (2 134 ears) were investigated, 345 (647 ears) had hearing impairment, the prevalence was 32. 33% . High-frequency hearing loss occurred on 320 workers (614 ears) , speech frequency hearing loss on 25 workers (33 ears). Of 111 workers in control group, 4 workers (6 ears) had hearing impairment, all were high-frequency hearing loss, the prevalence was 3. 60%. The prevalence of hearing impairment of noise group was obviously higher than that of control group, with significant difference ( x2 = 39. 80,P <0.01). [Conclusion] Noise influences the high-frequency hearing threshold of workers with exposure . And the risk of hearing loss rate inceases with the extending of service length. It is suggested to strengthen personal protection, to establish health records and control occupational noise deafness.%目的 对某飞机维修工程公司噪声作业人员进行调查,分析该公司噪声作业人员的听力损伤现状,以期对预防职业性听力损伤和职业性噪声聋提出建议.方法 设噪声作业组1067人,非噪声接触人员111人为对照组,均使用丹麦产MM-622型纯音听力计(经零级校正),对两组人员双耳0.5、1.0、2.0、3.0、4.0、6.0 kHz的纯音气导进行检查,听力损伤的评定标准:语频听损以0

  19. Airframe-Jet Engine Integration Noise

    Science.gov (United States)

    Tam, Christopher; Antcliff, Richard R. (Technical Monitor)

    2003-01-01

    It has been found experimentally that the noise radiated by a jet mounted under the wing of an aircraft exceeds that of the same jet in a stand-alone environment. The increase in noise is referred to as jet engine airframe integration noise. The objectives of the present investigation are, (1) To obtain a better understanding of the physical mechanisms responsible for jet engine airframe integration noise or installation noise. (2) To develop a prediction model for jet engine airframe integration noise. It is known that jet mixing noise consists of two principal components. They are the noise from the large turbulence structures of the jet flow and the noise from the fine scale turbulence. In this investigation, only the effect of jet engine airframe interaction on the fine scale turbulence noise of a jet is studied. The fine scale turbulence noise is the dominant noise component in the sideline direction. Thus we limit out consideration primarily to the sideline.

  20. 14 CFR 21.24 - Issuance of type certificate: primary category aircraft.

    Science.gov (United States)

    2010-01-01

    ... aircraft's type design or supplemental type design. (c) For aircraft manufactured outside of the United... requirements; the applicant has conducted appropriate flight, structural, propulsion, and systems tests...; the type design complies with the airworthiness standards and noise requirements established for...

  1. Technology approach to aero engine noise reduction

    Energy Technology Data Exchange (ETDEWEB)

    Neise, W.; Enghardt, L. [Deutsches Zentrum fur Luft-und Raumfahrt -DLR, Institute of Propulsion Technology, Turbulence Research Div., Berlin (Germany)

    2003-07-01

    Transportation noise is one of the most pressing environmental problems of modern societies. Aircraft noise is second only to road traffic noise in drawing complaints from the public about noise pollution. Therefore intensive research efforts are necessary on the national levels as well as the European level to reduce the noise load around airports. The most effective and economical way to reach this goal is noise reduction at the source. The aero engines of today's transport aircraft are the dominant noise sources for most flight conditions, although air-frame noise does play an important role for landing aircraft. In this paper noise reduction studies for aero engines are described in which DLR are involved. The topics discussed are low noise fan design, active noise control using wall-flush loudspeakers as secondary sources, ANC using active stators as secondary sources, ANC using flow induced secondary sources at the rotor tips, reduction of low-pressure turbine noise, and flight tests for validation of add-on noise reduction devices. (authors)

  2. Small Engine Technology (SET) Task 24 Business and Regional Aircraft System Studies

    Science.gov (United States)

    Lieber, Lysbeth

    2003-01-01

    This final report has been prepared by Honeywell Engines & Systems, Phoenix, Arizona, a unit of Honeywell International Inc., documenting work performed during the period June 1999 through December 1999 for the National Aeronautics and Space Administration (NASA) Glenn Research Center, Cleveland, Ohio, under the Small Engine Technology (SET) Program, Contract No. NAS3-27483, Task Order 24, Business and Regional Aircraft System Studies. The work performed under SET Task 24 consisted of evaluating the noise reduction benefits compared to the baseline noise levels of representative 1992 technology aircraft, obtained by applying different combinations of noise reduction technologies to five business and regional aircraft configurations. This report focuses on the selection of the aircraft configurations and noise reduction technologies, the prediction of noise levels for those aircraft, and the comparison of the noise levels with those of the baseline aircraft.

  3. Community reaction to noise from power stations

    International Nuclear Information System (INIS)

    Community reaction is a major consideration in noise control. The relationship between noise exposure and community reaction has received considerable attention in relation to railway, traffic, aircraft and impulsive noise. The results have shown a number of features in common, including: similarly shaped noise/reaction functions; similar results across different measurement techniques and cultures, noise/reaction correlations based on individual respondent data are low (mean r = 0.42 ± 0.12: Job, 1988), although correlations of .58 and above have been reported correlations based on data grouped by noise exposure are generally high and relatively unaffected by the type of noise studied whereas correlations based on individual data tend to be lower for impulsive noise than for transportation noise attitude to the noise source and sensitivity to noise shows strong correlations with reaction. This paper reports that the present study was undertaken in order toe establish over a wider range of noise exposure whether community reaction to power station noise is similar to reaction to other types of non-impulsive noise. It is possible that reaction is different given important differences in the source of the noise which may affect attitude. Attitudes towards power stations may be more positive than attitudes to aircraft or rail noise for example, because almost all respondents use electricity regularly every day. Further, the power stations in the present study provided employment for the relatively small surrounding communities

  4. Noise Pollution

    Science.gov (United States)

    ... Overview » Title IV - Noise Pollution Title IV - Noise Pollution The 1990 Clean Air Act Amendments added a ... abatement 7642 Authorization of appropriations What is Noise Pollution? The traditional definition of noise is “unwanted or ...

  5. Aircraft cybernetics

    Science.gov (United States)

    1977-01-01

    The use of computers for aircraft control, flight simulation, and inertial navigation is explored. The man-machine relation problem in aviation is addressed. Simple and self-adapting autopilots are described and the assets and liabilities of digital navigation techniques are assessed.

  6. 76 FR 11308 - Aviation Noise Impacts Roadmap Annual Meeting

    Science.gov (United States)

    2011-03-01

    ... on health and welfare; noise in national parks and wilderness; aircraft noise modeling; and costs of... TRANSPORTATION Federal Aviation Administration Aviation Noise Impacts Roadmap Annual Meeting AGENCY: Federal... interested persons that the First Annual Meeting of the Aviation Noise Impacts Roadmap will be held on...

  7. The associations between noise sensitivity, reported physical and mental health, perceived environmental quality, and noise annoyance

    Directory of Open Access Journals (Sweden)

    Dirk Schreckenberg

    2010-01-01

    Full Text Available One hundred and ninety residents around Frankfurt Airport (46% female; 17-80 years were interviewed concerning noise annoyance due to transportation noise (aircraft, road traffic, perceived mental and physical health, perceived environmental quality, and noise sensitivity. The aim of the analyses was to test whether noise sensitivity reflects partly general environmental sensitivity and is associated with an elevated susceptibility for the perception of mental and physical health. In this study, the reported physical and mental health variables were not associated with noise exposure but with noise annoyance, and were interpreted to reflect nonspecific codeterminants of annoyance rather than noise effects. Noise sensitivity was found to influence total noise annoyance and aircraft noise annoyance but to a lesser degree annoyance due to road traffic noise. Noise sensitivity was associated with reported physical health, but not with reported mental health. Noise-sensitive persons reported poorer environmental quality in their residential area than less sensitive persons in particular with regard to air traffic (including the facets noise, pollution, and contaminations and quietness. Other aspects of the perceived quality of the environment were scarcely associated with noise sensitivity. This indicates that noise sensitivity is more specific and a reliable predictor of responses to noise from the dominant source (in this case air traffic rather than a predictor of the individual perception of the environmental quality in general.

  8. Noise Reduction Technologies for Turbofan Engines

    Science.gov (United States)

    Huff, Dennis L.

    2007-01-01

    Significant progress continues to be made with noise reduction for turbofan engines. NASA has conducted and sponsored research aimed at reducing noise from commercial aircraft. Since it takes many years for technologies to be developed and implemented, it is important to have aggressive technology goals that lead the target entry into service dates. Engine noise is one of the major contributors to the overall sound levels as aircraft operate near airports. Turbofan engines are commonly used on commercial transports due to their advantage for higher performance and lower noise. The noise reduction comes from combinations of changes to the engine cycle parameters and low noise design features. In this paper, an overview of major accomplishments from recent NASA research programs for engine noise will be given.

  9. APPLICATION FOR AIRCRAFT TRACKING

    OpenAIRE

    Ostroumov, Ivan; Kuz’menko, Natalia

    2011-01-01

    Abstract. In the article the important problems of software development for aircraft tracking have beendiscussed. Position reports of ACARS have been used for aircraft tracking around the world.An algorithm of aircraft coordinates decoding and visualization of aircraft position on the map has beenrepresented.Keywords: ACARS, aircraft, internet, position, software, tracking.

  10. Supersonic Jet Noise: Main Sources and Reduction Methodologies

    Directory of Open Access Journals (Sweden)

    Mohammadreza Azimi

    2014-07-01

    Full Text Available The large velocity ratio and the presence of Shocks in the exhaust plume from low bypass engines or supersonic jetliners cause jet noise to be dominant component of overall aircraft noise, and therefore is an important issue in design of the next generation of civil supersonic transport. Jet noise reduction technology also has application in the design of highperformance tactical aircraft. Jet noise is of particular concern on aircraft carriers where it is necessary for deck crew to be in relatively close proximity to the aircraft at takeoff and landing. In this paper, a brief discussion about supersonic jet noise sources and a review of the main passive technologies employed for the reduction of supersonic jet noise are presented.

  11. Effect of aircraft noise on hearing of ground crew with different positions%飞机噪声对不同岗位机务人员听力的影响

    Institute of Scientific and Technical Information of China (English)

    张方; 冯潇炜; 曹新生; 谢文良; 梁锐明; 高璐璐; 张仲平

    2013-01-01

    目的:比较噪声对不同岗位机务人员听力的影响。方法选取某军区空军机务人员作为调查对象,按照工作岗位分为机械组(736人)、军械组(294人)、电子组(334人)、特设组(350人)四组。采用电测听仪检查所有被试人员纯音听力。结果四组机务人员均出现一定比例的听力障碍,分别为机械12.0%,军械9.5%,电子10.2%,特设12.0%;高频听力受损分别为机械45.1%,军械45.5%,电子34.8%,特设57.7%。特设组显著高于其他三组(P<0.01)。各组机务人员的高频听力受损的最敏感频率均为6000 Hz,在听力图上呈现典型的V形凹陷。结论噪声对机务人员的听力均有不良影响,高频听力受损发生率高,且以6000 Hz最为敏感,特设人员高频听力受损高于其他工种。%Objective We directed to study the effect of military aircraft noise on hearing of ground crew with different positions. Methods 1714 military ground crew were chosen for the survey. They were divided into 4 groups:Machinery (736), Ordnance (294), Avionics (334), and Special Equipment (350). Hearings of all subjects were tested by electric audiometer. Results Hearing damage occurred in all the four groups of ground crew as follows:Machinery 12.0%,Ordnance 9.5%,Avionics 10.2%, and Special Equipment 12.0%. The high-frequency hearing impairment were very common in ground crew:Machinery 45.1%,Ordnance 45.5%, Avionics 34.8%, and Special Equipment 57.7%, and the incidence for the Special Equipment was significantly higher than the other three groups (P<0.01). Meanwhile, the most sensitive frequency of the high-frequency hearing impairment occurred at 6000 Hz in all the four groups, suggesting a typical"V"-shaped trough in the audiogram. Conclusion For hearing damage, there was no apparent difference among different military ground crew, while high-frequency hearing impairment in the special equipment group was worse than the other

  12. Investigation of a jet-noise-shielding methodology

    OpenAIRE

    O'Reilly, Ciarán J.; Rice, Henry J.

    2015-01-01

    Ongoing research toward the reduction of environmental noise from aircraft is investigating the possible shielding of engine-noise sources by novel airframe configurations. To assess the noise-reduction benefits attainable from such configurations, it is necessary to develop appropriate acoustic evaluation tools. In this paper, a jet-noise-shielding- prediction methodology is described. The Tam–Auriault (“Jet Mixing Noise from Fine-Scale Turbulence,” AIAA Journal, Vol. 37, No. 2, 1999, pp. 14...

  13. Snowmobile noise

    OpenAIRE

    Liikonen, Larri; Alanko, Mikko; Jokinen, Sirpa; Niskanen, Ilkka; Virrankoski, Lauri

    2007-01-01

    Planning snowmobiling routes and considering the possible need for off-road traffic restrictions requires that the noise impact of snowmobile traffic is known. The objective of this report was to take off-road readings in order to determine snowmobile noise emissions and the spread of noise from snowmobile routes into the environment. Based on the readings taken, it can be said that the noise zones created by snowmobile traffic are quite narrow at current traffic levels. Noise pollution ca...

  14. Industrial Noise

    OpenAIRE

    Mehran zolfaghari

    1996-01-01

    Various risk factors in industrial environments can affect hearing status and healthy in today’s modern society. Noise control and hearing conservation program is very crucial in preventing workers exposed to high levels of noise in the work places. In the current article we are going to discuss issues such as industrial noise control, noise characteristics and standards and techniques for noise control. Then the methods for individual hearing conservation and medical care will be described i...

  15. Adaptive noise

    OpenAIRE

    Viney, Mark; Reece, Sarah E.

    2013-01-01

    In biology, noise implies error and disorder and is therefore something which organisms may seek to minimize and mitigate against. We argue that such noise can be adaptive. Recent studies have shown that gene expression can be noisy, noise can be genetically controlled, genes and gene networks vary in how noisy they are and noise generates phenotypic differences among genetically identical cells. Such phenotypic differences can have fitness benefits, suggesting that evolution can shape noise ...

  16. Multi-index Evaluation Metrics System of Aircraft Noise in Military Airports%军用机场飞机噪声环境联合指标评价体系研究

    Institute of Scientific and Technical Information of China (English)

    石鑫刚; 董豪昊; 邵斌; 刘洲; 唐志强

    2016-01-01

    通过分析军用机场飞机噪声影响范围大、单次飞行事件噪声影响突出和噪声影响不均匀的特点,指出用现有噪声评价指标评价军用机场飞机噪声环境的不足,提出Ldn、LAmax和高峰时段RLdn的军用机场飞机噪声环境联合指标评价体系,并对联合指标评价体系进行合理性分析,提出相应噪声限值标准。对三个军用机场噪声测试及噪声主观反应调查验证了其可行性。%The airport noise in military airports has an influence in very large adjacent area, even a single flight can give significant and inhomogeneous affect of noise. This paper pointed out the inadequacy of the current noise evaluation index in evaluation of the environment noise in military airports. A multi-index metrics system in noise evaluation which consist of Ldn, LAmax and rush hour RLdn was proposed. The rationality of this system was analyzed and the limitation values of the noise were put forward. Finally, through the noise measurement and subjective response investigation of the noise for three military airports, the feasibility of this system was verified.

  17. Small Engine Technology (SET). Task 33: Airframe, Integration, and Community Noise Study

    Science.gov (United States)

    Lieber, Lys S.; Elkins, Daniel; Golub, Robert A. (Technical Monitor)

    2002-01-01

    Task Order 33 had four primary objectives as follows: (1) Identify and prioritize the airframe noise reduction technologies needed to accomplish the NASA Pillar goals for business and regional aircraft. (2) Develop a model to estimate the effect of jet shear layer refraction and attenuation of internally generated source noise of a turbofan engine on the aircraft system noise. (3) Determine the effect on community noise of source noise changes of a generic turbofan engine operating from sea level to 15,000 feet. (4) Support lateral attenuation experiments conducted by NASA Langley at Wallops Island, VA, by coordinating opportunities for Contractor Aircraft to participate as a noise source during the noise measurements. Noise data and noise prediction tools, including airframe noise codes, from the NASA Advanced Subsonic Technology (AST) program were applied to assess the current status of noise reduction technologies relative to the NASA pillar goals for regional and small business jet aircraft. In addition, the noise prediction tools were applied to evaluate the effectiveness of airframe-related noise reduction concepts developed in the AST program on reducing the aircraft system noise. The AST noise data and acoustic prediction tools used in this study were furnished by NASA.

  18. Effect of cessation of late-night landing noise on sleep electrophysiology in the home

    Science.gov (United States)

    Pearsons, K. S.; Fidell, S.; Bennett, R. L.; Friedman, J.; Globus, G.

    1974-01-01

    Simultaneous measurements of noise exposure and sleep electrophysiology were made in homes before and after cessation of nighttime aircraft landing noise. Six people were tested, all of whom had been exposed to intense aircraft noise for at least two years. Noise measurements indicated a large reduction in the hourly noise level during nighttime hours, but no charge during the daytime hours. Sleep measures indicated no dramatic changes in sleep patterns either immediately after a marked change in nocturnal noise exposure or approximately a month thereafter. No strong relationship was observed between noise level and sleep disturbances over the range from 60 to 90 db(A).

  19. Aircraft Structure’s Response Prediction Analysis and Experimental Study in High-strength Broadband Noise Environments%飞行器结构在高强宽频噪声环境下的响应预示分析与试验研究

    Institute of Scientific and Technical Information of China (English)

    林华刚; 闫云聚; 李鹏博

    2016-01-01

    超高声速飞行器的动力学环境频域宽,使用有限元/边界元方法预示其振动响应存在困难。基于统计能量分析(Statistical energy analysis, SEA)理论建立某型高速飞行器声振耦合动力学模型,用理论解析和经验公式的方法确定各子系统的输入参数,以实际噪声试验条件作为飞行器 SEA 模型的输入激励,对飞行器舱内噪声声压级和子系统振动加速度响应进行预示,并与试验结果进行比较。结果显示,子系统振动加速度功率谱密度(Power spectral density, PSD)在中高频与试验结果基本一致,舱内声压在整个频段内误差小于3 dB,因此建立的动力学模型和采用的计算方法是可靠的,解决了有限元、边界元在中高频声振响应问题计算的局限性。通过传递路径分析寻找出舱内声场的主要来源,提出以损耗因子为设计变量的噪声控制与优化方法,利用遗传算法实现了这一非线性约束问题求解,为研究飞行器结构和复杂动力学环境以及飞行器降噪优化设计提供有效的手段。%Since dynamic environment of the hypersonic aircraft has a wide frequency domain, it is difficult to predict the vibration response with finite element methods. A certain type of high-speed aircraft’s vibro-acoustic dynamics model is established based on statistical energy analysis (SEA) theory. By using theory analytical method and the empirical formula to determine the input parameters of each subsystem, setting the actual noise test conditions as the input incentives of the SEA model, the aircraft cabin’s noise pressure level and the vibration acceleration response of the subsystems are predicted, and compared to the test results. The results show that the acceleration power spectral density (PSD) of subsystem has a good consistency with the results of test in the middle and high frequency and the error of sound pressure level in cabin throughout the

  20. Unjust noise

    OpenAIRE

    Paul Voice

    2009-01-01

    In this paper I argue that noise is a significant source of social harm and thoseharmed by noise often suffer not merely a misfortune but an injustice. I arguethat noise is a problem of justice in two ways; firstly, noise is a burden of socialcooperation and so the question of the distribution of this burden arises. And,secondly, some noises, although burdensome, are nevertheless just becausethey arise from practices that are ‘reasonable’. I offer a number of distinctions,between necessary an...

  1. Propulsion controlled aircraft computer

    Science.gov (United States)

    Cogan, Bruce R. (Inventor)

    2010-01-01

    A low-cost, easily retrofit Propulsion Controlled Aircraft (PCA) system for use on a wide range of commercial and military aircraft consists of an propulsion controlled aircraft computer that reads in aircraft data including aircraft state, pilot commands and other related data, calculates aircraft throttle position for a given maneuver commanded by the pilot, and then displays both current and calculated throttle position on a cockpit display to show the pilot where to move throttles to achieve the commanded maneuver, or is automatically sent digitally to command the engines directly.

  2. Modeling and Prediction of Krueger Device Noise

    Science.gov (United States)

    Guo, Yueping; Burley, Casey L.; Thomas, Russell H.

    2016-01-01

    This paper presents the development of a noise prediction model for aircraft Krueger flap devices that are considered as alternatives to leading edge slotted slats. The prediction model decomposes the total Krueger noise into four components, generated by the unsteady flows, respectively, in the cove under the pressure side surface of the Krueger, in the gap between the Krueger trailing edge and the main wing, around the brackets supporting the Krueger device, and around the cavity on the lower side of the main wing. For each noise component, the modeling follows a physics-based approach that aims at capturing the dominant noise-generating features in the flow and developing correlations between the noise and the flow parameters that control the noise generation processes. The far field noise is modeled using each of the four noise component's respective spectral functions, far field directivities, Mach number dependencies, component amplitudes, and other parametric trends. Preliminary validations are carried out by using small scale experimental data, and two applications are discussed; one for conventional aircraft and the other for advanced configurations. The former focuses on the parametric trends of Krueger noise on design parameters, while the latter reveals its importance in relation to other airframe noise components.

  3. Critical Low-Noise Technologies Being Developed for Engine Noise Reduction Systems Subproject

    Science.gov (United States)

    Grady, Joseph E.; Civinskas, Kestutis C.

    2004-01-01

    NASA's previous Advanced Subsonic Technology (AST) Noise Reduction Program delivered the initial technologies for meeting a 10-year goal of a 10-dB reduction in total aircraft system noise. Technology Readiness Levels achieved for the engine-noise-reduction technologies ranged from 4 (rig scale) to 6 (engine demonstration). The current Quiet Aircraft Technology (QAT) project is building on those AST accomplishments to achieve the additional noise reduction needed to meet the Aerospace Technology Enterprise's 10-year goal, again validated through a combination of laboratory rig and engine demonstration tests. In order to meet the Aerospace Technology Enterprise goal for future aircraft of a 50- reduction in the perceived noise level, reductions of 4 dB are needed in both fan and jet noise. The primary objectives of the Engine Noise Reduction Systems (ENRS) subproject are, therefore, to develop technologies to reduce both fan and jet noise by 4 dB, to demonstrate these technologies in engine tests, and to develop and experimentally validate Computational Aero Acoustics (CAA) computer codes that will improve our ability to predict engine noise.

  4. Active Control of Aerodynamic Noise Sources

    Science.gov (United States)

    Reynolds, Gregory A.

    2001-01-01

    Aerodynamic noise sources become important when propulsion noise is relatively low, as during aircraft landing. Under these conditions, aerodynamic noise from high-lift systems can be significant. The research program and accomplishments described here are directed toward reduction of this aerodynamic noise. Progress toward this objective include correction of flow quality in the Low Turbulence Water Channel flow facility, development of a test model and traversing mechanism, and improvement of the data acquisition and flow visualization capabilities in the Aero. & Fluid Dynamics Laboratory. These developments are described in this report.

  5. Nocturnal sleep disturbance through aircraft noise. Do wakening reactions begin at maximum levels of 60 decibels (A)?; Naechtliches Erwachen durch Fluglaerm. Beginnen Aufwachreaktionen bei Maximalpegeln von 60 Dezibel(A)?

    Energy Technology Data Exchange (ETDEWEB)

    Maschke, C. [Technische Univ. Berlin (Germany). Inst. fuer Technische Akustik; Hecht, K. [Inst. fuer psychosoziale Gesundheit, Berlin (Germany); Wolf, U. [Bundesgesundheitsamt, Berlin (Germany). Robert-Koch-Institut

    2001-10-01

    The present paper is not concerned with the question whether it makes sense from the viewpoint of preventive medicine to use the onset of noise-induced wakening reactions as the sole criterion for nocturnal noise protection. On this point reference is made to the mediation process ''Extension of Frankfurt am Main Airport''. The attending experts (Bullinger, Griefhahn, Hecht, Kastka, Maschke, Spreng) were agreed that 52 to 53 dB (A) should be regarded as the maximum nocturnal noise level at which vegetative impairment begins. According to present knowledge the minimum protection goal that must be demanded, therefore, is to ensure that sleeping persons are exposed to maximum continuous nocturnal noise levels of less than 52 dB (A). [German] Im vorliegenden Beitrag wird nicht der Frage nachgegangen, ob es praeventivmedizinisch sinnvoll ist, ein naechtliches Schutzkriterium allein auf den Beginn von laermbedingten Aufwachreaktionen abzustellen. In diesem Zusammenhang ist auf das Mediationsverfahren ''Ausbau Flughafen Frankfurt/Main'' hinzuweisen. Von den anwesenden Experten (Bullinger, Griefahn, Hecht, Kastka, Maschke, Spreng) wurde uebereinstimmend ein naechtlicher Maximalpegel von 52 bis 53 dB(A) als Beginn fuer vegetative Beeintraechtigungen angesehen. Nach heutigen Kenntnisstand ist daher als minimales Schutzziel zu fordern, dass regelmaessige naechtliche Maximalpegel von 52 dB(A) am Ohr des Schlaefers vermieden bzw. unterschritten werden sollten. (orig.)

  6. 14 CFR Appendix B to Part 150 - Noise Compatibility Programs

    Science.gov (United States)

    2010-01-01

    ... feasible, will confine severe aircraft YDNL values of Ldn 75 dB or greater to areas included within the... between the Ldn 65 and 75 dB contours. Sec. B150.3Requirement for noise map. (a) It is required that a.... (2) A noise contour of Ldn 70 dB resulting from aircraft operations and data related to the Ldn 70...

  7. Prediction of noise radiation from basic configurations of landing gears by means of computational aeroacoustics

    NARCIS (Netherlands)

    Drage, P.; Wiesler, B.; Beek, P.J.G. van; Lier, L.J. van; Parchen, R.R.; Tibaut, P.

    2007-01-01

    Noise radiation from aircraft during the takeoff and landing has become a major issue for inhabitants living in the vicinity of airports and thus for regulation authorities and aircraft developers. However the numerical simulation of aeroacoustic noise, especially for complex geometries like a landi

  8. Feminizing noise

    OpenAIRE

    Thompson, Marie

    2014-01-01

    Marie will explore the relationship between constructions of femininity and noise, which is understood here as an affective transformative force, rather than simply as unwanted sound. She will suggest that ‘feminine’ noises are often deemed negative; not because of what they mean, but as a result of the transformations they threaten to induce. Marie will raise questions around essentialism – does talking of a feminine or feminized noise require us to adopt an essentialist position, or can an ...

  9. NOISE REGULATION

    OpenAIRE

    Cristina Voican; Constantin Stanescu

    2012-01-01

    Noise regulation includes statutes or guidelines relating to sound transmission established by national, state or provincial and municipal levels of government. After the watershed passage of the United States Noise Control Act of 1972, other local and state governments passed further regulations. Although the UK and Japan enacted national laws in 1960 and 1967 respectively, these laws were not at all comprehensive or fully enforceable as to address generally rising ambient noise, enforceable...

  10. Cardiovascular effects of environmental noise: Research in The Netherlands

    Directory of Open Access Journals (Sweden)

    Elise van Kempen

    2011-01-01

    Full Text Available The impact of environmental noise on public health, in The Netherlands, is limited: Less than 1% of the myocardial infarction cases per year are attributable to long-term exposure to road traffic noise. Furthermore, although the Dutch noise policy is not directed to prevent cardiovascular disease due to noise exposure, health does play a role in Dutch noise policy. These are the main conclusions of a systematic review of Dutch observational studies, investigating the possible impact of road traffic and aircraft noise exposure on the cardiovascular system. Since 1970, 14 Dutch studies were published investigating the possible impact of road traffic and aircraft noise exposure on the cardiovascular system. Within these studies a large variety of outcomes were investigated, ranging from blood pressure changes to cardiovascular mortality. The results of the studies were not consistent and only weak associations were found.

  11. Noise Traders

    OpenAIRE

    James Dow; Gary Gorton

    2006-01-01

    Noise traders are agents whose theoretical existence has been hypothesized as a way of solving certain fundamental problems in Financial Economics. We briefly review the literature on noise traders. The is an entry for The New Palgrave: A Dictionary of Economics, 2nd Edition (Palgrave Macmillan: New York), edited by Steven N. Durlauf and Lawrence E. Blume, forthcoming in 2008.

  12. Recent Progress in Engine Noise Reduction Technologies

    Science.gov (United States)

    Huff, Dennis; Gliebe, Philip

    2003-01-01

    Highlights from NASA-funded research over the past ten years for aircraft engine noise reduction are presented showing overall technical plans, accomplishments, and selected applications to turbofan engines. The work was sponsored by NASA's Advanced Subsonic Technology (AST) Noise Reduction Program. Emphasis is given to only the engine noise reduction research and significant accomplishments that were investigated at Technology Readiness Levels ranging from 4 to 6. The Engine Noise Reduction sub-element was divided into four work areas: source noise prediction, model scale tests, engine validation, and active noise control. Highlights from each area include technologies for higher bypass ratio turbofans, scarf inlets, forward-swept fans, swept and leaned stators, chevron/tabbed nozzles, advanced noise prediction analyses, and active noise control for fans. Finally, an industry perspective is given from General Electric Aircraft Engines showing how these technologies are being applied to commercial products. This publication contains only presentation vu-graphs from an invited lecture given at the 41st AIAA Aerospace Sciences Meeting, January 6-9, 2003.

  13. General Aviation Interior Noise. Part 1; Source/Path Identification

    Science.gov (United States)

    Unruh, James F.; Till, Paul D.; Palumbo, Daniel L. (Technical Monitor)

    2002-01-01

    There were two primary objectives of the research effort reported herein. The first objective was to identify and evaluate noise source/path identification technology applicable to single engine propeller driven aircraft that can be used to identify interior noise sources originating from structure-borne engine/propeller vibration, airborne propeller transmission, airborne engine exhaust noise, and engine case radiation. The approach taken to identify the contributions of each of these possible sources was first to conduct a Principal Component Analysis (PCA) of an in-flight noise and vibration database acquired on a Cessna Model 182E aircraft. The second objective was to develop and evaluate advanced technology for noise source ranking of interior panel groups such as the aircraft windshield, instrument panel, firewall, and door/window panels within the cabin of a single engine propeller driven aircraft. The technology employed was that of Acoustic Holography (AH). AH was applied to the test aircraft by acquiring a series of in-flight microphone array measurements within the aircraft cabin and correlating the measurements via PCA. The source contributions of the various panel groups leading to the array measurements were then synthesized by solving the inverse problem using the boundary element model.

  14. Designing A Conventional Aircraft

    OpenAIRE

    Sonei, Arash

    2014-01-01

    This paper is explaining the important design phases of dimensioning an unmanned conventional aircraft from scratch and will also design one according to a few chosen requirements. The design phases discussed will be all from wing dimensioning to stability and spin recovery, aircraft performance requirements and how to select a motor which overcomes these. As well as the optimal rate of climb for improved efficiency is discussed. In the end an aircraft which manages the set requirements and i...

  15. Lightning effects on aircraft

    Science.gov (United States)

    1977-01-01

    Direct and indirect effects of lightning on aircraft were examined in relation to aircraft design. Specific trends in design leading to more frequent lightning strikes were individually investigated. These trends included the increasing use of miniaturized, solid state components in aircraft electronics and electric power systems. A second trend studied was the increasing use of reinforced plastics and other nonconducting materials in place of aluminum skins, a practice that reduces the electromagnetic shielding furnished by a conductive skin.

  16. Chasing Noise

    OpenAIRE

    Mendel, Brock; Shleifer, Andrei

    2012-01-01

    We present a simple model in which rational but uninformed traders occasionally chase noise as if it were information, thereby amplifying sentiment shocks and moving prices away from fundamental values. We fill a theoretical gap in the literature by showing conditions under which noise traders can have an impact on market equilibrium disproportionate to their size in the market. The model offers a partial explanation for the surprisingly low market price of financial risk in the Spring of 2007.

  17. Crackling Noise

    OpenAIRE

    Sethna, James P.; Dahmen, Karin A.; Christopher R Myers

    2001-01-01

    Crackling noise arises when a system responds to changing external conditions through discrete, impulsive events spanning a broad range of sizes. A wide variety of physical systems exhibiting crackling noise have been studied, from earthquakes on faults to paper crumpling. Because these systems exhibit regular behavior over many decades of sizes, their behavior is likely independent of microscopic and macroscopic details, and progress can be made by the use of very simple models. The fact tha...

  18. Noise Bubbles

    OpenAIRE

    Mario Forni; Luca Gambetti; Marco Lippi; Luca Sala

    2014-01-01

    We introduce noisy information into a standard present value stock price model. Agents receive a noisy signal about the structural shock driving future dividend variations. The resulting equilibrium stock price includes a transitory component — the "noise bubble" — which can be responsible for boom and bust episodes unrelated to economic fundamentals. We propose a non-standard VAR procedure to estimate the structural shock and the "noise" shock, their impulse response functions and the bubble...

  19. Signal processing of jet noise from flyover test data

    Science.gov (United States)

    Kelly, Jeffrey J.; Wilson, Mark R.

    1993-01-01

    Narrow-band spectra characterizing jet noise are constructed from flyover acoustic measurements. Radar and c-band tracking systems provided the aircraft position histories which enabled directivity and smear angles from the aircraft to each microphone to be computed. These angles are based on source emission time and thus give some idea about the directivity of the radiated sound field due to jet noise. Simulated spectra are included in the paper to demonstrate spectral broadening due to smear angle. The acoustic data described in the study has application to community noise analysis, noise source characterization and validation of prediction models. Both broadband-shock noise and turbulent mixing noise are observed in the spectra. A detailed description of the signal processing procedures is provided.

  20. Environmental Impact Evaluation of Aircraft at System-of-Systems Level

    NARCIS (Netherlands)

    Schroijen, M.J.T.; Van Tooren, M.J.L.; Voskuijl, M.; Curran, R.

    2011-01-01

    Next generations of civil transport aircraft will need to be evaluated not only against their behaviour as an aircraft system but also as a part of the larger air transport system. In addition to this are the sustainability issues related to for instance noise and emissions, represented by environme

  1. Energy efficient engine flight propulsion system: Aircraft/engine integration evaluation

    Science.gov (United States)

    Patt, R. F.

    1980-01-01

    Results of aircraft/engine integration studies conducted on an advanced flight propulsion system are reported. Economic evaluations of the preliminary design are included and indicate that program goals will be met. Installed sfc, DOC, noise, and emissions were evaluated. Aircraft installation considerations and growth were reviewed.

  2. Energy efficient engine: Propulsion system-aircraft integration evaluation

    Science.gov (United States)

    Owens, R. E.

    1979-01-01

    Flight performance and operating economics of future commercial transports utilizing the energy efficient engine were assessed as well as the probability of meeting NASA's goals for TSFC, DOC, noise, and emissions. Results of the initial propulsion systems aircraft integration evaluation presented include estimates of engine performance, predictions of fuel burns, operating costs of the flight propulsion system installed in seven selected advanced study commercial transports, estimates of noise and emissions, considerations of thrust growth, and the achievement-probability analysis.

  3. Multispectral imaging of aircraft exhaust

    Science.gov (United States)

    Berkson, Emily E.; Messinger, David W.

    2016-05-01

    Aircraft pollutants emitted during the landing-takeoff (LTO) cycle have significant effects on the local air quality surrounding airports. There are currently no inexpensive, portable, and unobtrusive sensors to quantify the amount of pollutants emitted from aircraft engines throughout the LTO cycle or to monitor the spatial-temporal extent of the exhaust plume. We seek to thoroughly characterize the unburned hydrocarbon (UHC) emissions from jet engine plumes and to design a portable imaging system to remotely quantify the emitted UHCs and temporally track the distribution of the plume. This paper shows results from the radiometric modeling of a jet engine exhaust plume and describes a prototype long-wave infrared imaging system capable of meeting the above requirements. The plume was modeled with vegetation and sky backgrounds, and filters were selected to maximize the detectivity of the plume. Initial calculations yield a look-up chart, which relates the minimum amount of emitted UHCs required to detect the presence of a plume to the noise-equivalent radiance of a system. Future work will aim to deploy the prototype imaging system at the Greater Rochester International Airport to assess the applicability of the system on a national scale. This project will help monitor the local pollution surrounding airports and allow better-informed decision-making regarding emission caps and pollution bylaws.

  4. HEALTH HAZARDS ASSOCIATED WITH NOISE IN URBAN AREA

    OpenAIRE

    Sreejata Biswas

    2014-01-01

    Noise or unwanted sound is an environmental stressor. At the international level studies are based on the auditory and non-auditory effects of aircraft noise mostly. The present survey was conducted among people exposed to loud noise in Kolkata, a metropolitan city in India. The study area includes railway stations of Sealdah and Dumdum and music shops in Chandni Chowk. The study was conducted among the working class people among whom the adverse health effects may lead to productivity loss w...

  5. Vienna international airport noise abatement

    Directory of Open Access Journals (Sweden)

    Heidelinde Jelinek-Nigitz

    2016-03-01

    Full Text Available Purpose: On the topic of sustainable aviation a study was carried out to measure the difference between the actual change in air traffic noise and the airport’s residents’ perception of the noise change at Vienna International Airport. Therefore, a questionnaire was developed in cooperation with the airport and an online survey was conducted. Design/methodology/approach: For the survey of the opinion of the affected population of the surrounding communities, a web based online questionnaire is created and distributed via various channels including e-mail, and online forums. After the basic structure of the questionnaire had been defined, the questions were developed in cooperation with employees form the environmental department of VIE, who had a sustainable influence on the questions’ order and formulation. As the survey was supposed to be answered by residents around VIE. Findings: Results of the online study show that only parts of the participants are affected by air traffic noise at VIE. Even less experienced a significant change over the last five years. About one third of the participants stated that they are affected by air traffic noise in one way or another. The majority of these people live in Lower Austria, the federal state in which the airport is located. The participants obviously judge air traffic noise during day time more importantly than air traffic noise at night. Research limitations/implications: Due to the low number of returns, no statistically relevant conclusions can be drawn, the results of the survey can be used to make some general statements. Originality/value: Economic growth and deregulation lead to growing aircraft operations. Vienna International Airport with its approximately 260,000 flight movements per year is the biggest airport in Austria and a major hub in Europe. The combination of constantly growing air transport and the resulting noise exposure, as well as the steadily increasing

  6. Recent Developments in U.S. Engine Noise Reduction Research

    Science.gov (United States)

    Bridges, James; Envia, Edmane; Huff, Dennis

    2001-01-01

    Aircraft engine noise research in the United States has made considerable progress over the past 10 years for both subsonic and supersonic flight applications. The Advanced Subsonic Technology (AST) Noise Reduction Program started in 1994 and will be completed in 2001 without major changes to program plans and funding levels. As a result, significant progress has been made toward the goal of reducing engine source noise by 6 EPNdB (Effective Perceived Noise level in decibels). This paper will summarize some of the significant accomplishments from the subsonic engine noise research performed over the past 10 years. The review is by no means comprehensive and only represents a sample of major accomplishments.

  7. UHB Engine Fan Broadband Noise Reduction Study

    Science.gov (United States)

    Gliebe, Philip R.; Ho, Patrick Y.; Mani, Ramani

    1995-01-01

    A study has been completed to quantify the contribution of fan broadband noise to advanced high bypass turbofan engine system noise levels. The result suggests that reducing fan broadband noise can produce 3 to 4 EPNdB in engine system noise reduction, once the fan tones are eliminated. Further, in conjunction with the elimination of fan tones and an increase in bypass ratio, a potential reduction of 7 to 10 EPNdB in system noise can be achieved. In addition, an initial assessment of engine broadband noise source mechanisms has been made, concluding that the dominant source of fan broadband noise is the interaction of incident inlet boundary layer turbulence with the fan rotor. This source has two contributors, i.e., unsteady life dipole response and steady loading quadrupole response. The quadrupole contribution was found to be the most important component, suggesting that broadband noise reduction can be achieved by the reduction of steady loading field-turbulence field quadrupole interaction. Finally, for a controlled experimental quantification and verification, the study recommends that further broadband noise tests be done on a simulated engine rig, such as the GE Aircraft Engine Universal Propulsion Simulator, rather than testing on an engine statically in an outdoor arena The rig should be capable of generating forward and aft propagating fan noise, and it needs to be tested in a large freejet or a wind tunnel.

  8. Cable Tensiometer for Aircraft

    Science.gov (United States)

    Nunnelee, Mark (Inventor)

    2008-01-01

    The invention is a cable tensiometer that can be used on aircraft for real-time, in-flight cable tension measurements. The invention can be used on any aircraft cables with high precision. The invention is extremely light-weight, hangs on the cable being tested and uses a dual bending beam design with a high mill-volt output to determine tension.

  9. Aircraft operations management manual

    Science.gov (United States)

    1992-01-01

    The NASA aircraft operations program is a multifaceted, highly diverse entity that directly supports the agency mission in aeronautical research and development, space science and applications, space flight, astronaut readiness training, and related activities through research and development, program support, and mission management aircraft operations flights. Users of the program are interagency, inter-government, international, and the business community. This manual provides guidelines to establish policy for the management of NASA aircraft resources, aircraft operations, and related matters. This policy is an integral part of and must be followed when establishing field installation policy and procedures covering the management of NASA aircraft operations. Each operating location will develop appropriate local procedures that conform with the requirements of this handbook. This manual should be used in conjunction with other governing instructions, handbooks, and manuals.

  10. Population-Based Questionnaire Survey on Health Effects of Aircraft Noise on Residents Living around U.S. Airfields in the RYUKYUS—PART II: AN Analysis of the Discriminant Score and the Factor Score

    Science.gov (United States)

    HIRAMATSU, K.; MATSUI, T.; MIYAKITA, T.; ITO, A.; TOKUYAMA, T.; OSADA, Y.; YAMAMOTO, T.

    2002-02-01

    Discriminant function values of psychosomatics and neurosis are calculated using the 12 scale scores of the Todai Health Index, a general health questionnaire, obtained in the survey done around the Kadena and Futenma U.S. airfields in Okinawa, Japan. The total number of answers available for the analysis is 6301. Factor analysis is applied to the 12 scale scores by means of the principal factor method, and Oblimin rotation is done because the factors extracted are considered likely to correlate with each other to a greater or lesser extent. The logistic regression analysis is made with the independent variables of discriminant function (DF) values and factor scores and with the dependent variables of Ldn, age (six levels), sex, occupation (four categories) and the interaction of age and sex. Results indicate that the odds ratio of the DF values regarding psychosomatic disorder and of the score of somatic factor have clear dose-response relationship. The odds ratios of the DF value of neurosis and of the score of the mental factor increase in the area where noise exposure is very intense.

  11. USAF bioenvironmental noise data handbook. Volume 172: Hush-noise suppressor (Aero Systems Engineering, Incorporated) far-field noise

    Science.gov (United States)

    Lee, R. A.; Rau, T. H.; Jones, C.

    1982-07-01

    The hush-house noise suppressor was made by Aero Systems Engineering of Texas, Inc. for acoustical suppression of various AF fighter/trainer aircraft during ground runup operations. This report provides measured and extrapolated data defining the bioacoustic environments produced by several aircraft/engines operating in the hush-house suppressor for various engine power configurations. Far-field data measured at 20 locations are normalized to standard meteorological conditions and extrapolated from 75-8000 meters to derive sets of equal-value contours for seven acoustic measures as function of angle and distance from the source. Refer to Volume 1 of this handbook, 'USAF Bioenvironmental Noise Data Handbook, Vol 1: Organization, Content and Application,' AMRL-TR-75(1) 1975, for discussion of the objective and design of the handbook, the types of data presented, measurement procedures, instrumentation, data processing, definitions of quantities, symbols, equations, applications, limitations, etc. Data are presented for the following aircraft/engines operating in the hush-house noise suppressor: F-4, F-15, F-16, F-105, F-106, F-111F and T-38 aircraft and the TF41-A-1, J79-GE-15, F100-PW-100, J75-P19, J-75-P-17 and TF30-P-100 engines.

  12. Noise exposure and children's blood pressure and heart rate: the RANCH project.

    NARCIS (Netherlands)

    Kempen, Elise van; Kamp, I van; Fischer, P; Davies, Hugh W; Houthuijs, D; Stellato, Rebecca K; Clark, Charlotte; Stansfeld, Stephen A

    2006-01-01

    BACKGROUND: Conclusions that can be drawn from earlier studies on noise and children's blood pressure are limited due to inconsistent results, methodological problems, and the focus on school noise exposure. OBJECTIVES: To investigate the effects of aircraft and road traffic noise exposure on childr

  13. Application of Viscothermal Wave Propagation Theory for Reduction of Boundary Layer Induced Noise

    NARCIS (Netherlands)

    Wijnant, Y.H.; Hannink, M.H.C.; Boer, de A.

    2003-01-01

    Boundary layer induced noise, i.e. noise inside the aircraft resulting from the turbulent boundary layer enclosing the fuselage, is known to dominate air-cabin noise at cruise conditions. In this paper a method is described to design trim panels containing a large number of coupled tubes to effectiv

  14. Acoustic boundary control for quieter aircraft

    Science.gov (United States)

    Hirsch, Scott Michael

    1999-08-01

    There is a strong interest in reducing the volume of low- frequency noise in aircraft cabins. Active noise control (ANC), in which loudspeakers placed in the cabin are used to generate a sound field which will cancel these disturbances, is now a commercially available solution. A second control approach is active structural acoustic control (ASAC), which uses structural control forces to reduce sound transmitted into the cabin through the fuselage. Some of the goals of current research are to reduce the cost, weight, and bulk of these control systems, along with improving global control performance. This thesis introduces an acoustic boundary control (ABC) concept for active noise control in aircraft. This control strategy uses distributed actuator arrays along enclosure boundaries to reduce noise transmitted into the enclosure through the boundaries and to reduce global noise levels due to other disturbances. The motivation is to provide global pressure attenuation with small, lightweight control actuators. Analytical studies are conducted of acoustic boundary in two-dimensional and three-dimensional rectangular enclosures and in a finite cylindrical enclosure. The simulations provide insight into the control mechanisms of ABC and demonstrate potential advantages of ABC over traditional ANC and ASAC implementations. A key component of acoustic boundary control is the ``smart'' trim panel, a structurally modified aircraft trim panel for use as an acoustic control source. A prototype smart trim panel is built and tested. The smart trim panel is used as the control source in a real-time active noise control system in a laboratory- scale fuselage model. It is shown that the smart trim panel works as well as traditional loudspeakers for this application. A control signal scheduling approach is proposed which allows for a reduction in the computational burden of the real-time controller used in active noise control applications. This approach uses off-line system

  15. Detection of aeroacoustic sound sources on aircraft and wind turbines

    NARCIS (Netherlands)

    Oerlemans, Stefan

    2009-01-01

    This thesis deals with the detection of aeroacoustic sound sources on aircraft and wind turbines using phased microphone arrays. First, the reliability of the array technique is assessed using airframe noise measurements in open and closed wind tunnels. It is demonstrated that quantitative acoustic

  16. Engine Conceptual Design Studies for a Hybrid Wing Body Aircraft

    Science.gov (United States)

    Tong, Michael T.; Jones, Scott M.; Haller, William J.; Handschuh, Robert F.

    2009-01-01

    Worldwide concerns of air quality and climate change have made environmental protection one of the most critical issues in aviation today. NASA s current Fundamental Aeronautics Research program is directed at three generations of aircraft in the near, mid and far term, with initial operating capability around 2015, 2020, and 2030, respectively. Each generation has associated goals for fuel burn, NOx, noise, and field-length reductions relative to today s aircrafts. The research for the 2020 generation is directed at enabling a hybrid wing body (HWB) aircraft to meet NASA s aggressive technology goals. This paper presents the conceptual cycle and mechanical designs of the two engine concepts, podded and embedded systems, which were proposed for a HWB cargo freighter. They are expected to offer significant benefits in noise reductions without compromising the fuel burn.

  17. Active noise control using noise source having adaptive resonant frequency tuning through stiffness variation

    Science.gov (United States)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor); Renshaw, Anthony A. (Inventor); Hedeen, Robert A. (Inventor)

    1995-01-01

    A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by a plurality of force transmitting mechanisms which contact the noise radiating element. Each one of the force transmitting mechanisms includes an expandable element and a spring in contact with the noise radiating element so that excitation of the element varies the spring force applied to the noise radiating element. The elements are actuated by a controller which receives input of a signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the elements and causes the spring force applied to the noise radiating element to be varied. The force transmitting mechanisms can be arranged to either produce bending or linear stiffness variations in the noise radiating element.

  18. Towards Intelligent Control for Next Generation Aircraft

    Science.gov (United States)

    Acosta, Diana Michelle; KrishnaKumar, Kalmanje Srinvas; Frost, Susan Alane

    2008-01-01

    NASA Aeronautics Subsonic Fixed Wing Project is focused on mitigating the environmental and operation impacts expected as aviation operations triple by 2025. The approach is to extend technological capabilities and explore novel civil transport configurations that reduce noise, emissions, fuel consumption and field length. Two Next Generation (NextGen) aircraft have been identified to meet the Subsonic Fixed Wing Project goals - these are the Hybrid Wing-Body (HWB) and Cruise Efficient Short Take-Off and Landing (CESTOL) aircraft. The technologies and concepts developed for these aircraft complicate the vehicle s design and operation. In this paper, flight control challenges for NextGen aircraft are described. The objective of this paper is to examine the potential of state-of-the-art control architectures and algorithms to meet the challenges and needed performance metrics for NextGen flight control. A broad range of conventional and intelligent control approaches are considered, including dynamic inversion control, integrated flight-propulsion control, control allocation, adaptive dynamic inversion control, data-based predictive control and reinforcement learning control.

  19. Indirect combustion noise of auxiliary power units

    Science.gov (United States)

    Tam, Christopher K. W.; Parrish, Sarah A.; Xu, Jun; Schuster, Bill

    2013-08-01

    Recent advances in noise suppression technology have significantly reduced jet and fan noise from commercial jet engines. This leads many investigators in the aeroacoustics community to suggest that core noise could well be the next aircraft noise barrier. Core noise consists of turbine noise and combustion noise. There is direct combustion noise generated by the combustion processes, and there is indirect combustion noise generated by the passage of combustion hot spots, or entropy waves, through constrictions in an engine. The present work focuses on indirect combustion noise. Indirect combustion noise has now been found in laboratory experiments. The primary objective of this work is to investigate whether indirect combustion noise is also generated in jet and other engines. In a jet engine, there are numerous noise sources. This makes the identification of indirect combustion noise a formidable task. Here, our effort concentrates exclusively on auxiliary power units (APUs). This choice is motivated by the fact that APUs are relatively simple engines with only a few noise sources. It is, therefore, expected that the chance of success is higher. Accordingly, a theoretical model study of the generation of indirect combustion noise in an Auxiliary Power Unit (APU) is carried out. The cross-sectional areas of an APU from the combustor to the turbine exit are scaled off to form an equivalent nozzle. A principal function of a turbine in an APU is to extract mechanical energy from the flow stream through the exertion of a resistive force. Therefore, the turbine is modeled by adding a negative body force to the momentum equation. This model is used to predict the ranges of frequencies over which there is a high probability for indirect combustion noise generation. Experimental spectra of internal pressure fluctuations and far-field noise of an RE220 APU are examined to identify anomalous peaks. These peaks are possible indirection combustion noise. In the case of the

  20. SOLAR AIRCRAFT DESIGN

    OpenAIRE

    RAHMATI, Sadegh; GHASED, Amir

    2015-01-01

    Abstract. Generally domain Aircraft uses conventional fuel. These fuel having limited life, high cost and pollutant. Also nowadays price of petrol and other fuels are going to be higher, because of scarcity of those fuels. So there is great demand of use of non-exhaustible unlimited source of energy like solar energy. Solar aircraft is one of the ways to utilize solar energy. Solar aircraft uses solar panel to collect the solar radiation for immediate use but it also store the remaining part ...

  1. Hybrid Analysis of Engine Core Noise

    Science.gov (United States)

    O'Brien, Jeffrey; Kim, Jeonglae; Ihme, Matthias

    2015-11-01

    Core noise, or the noise generated within an aircraft engine, is becoming an increasing concern for the aviation industry as other noise sources are progressively reduced. The prediction of core noise generation and propagation is especially challenging for computationalists since it involves extensive multiphysics including chemical reaction and moving blades in addition to the aerothermochemical effects of heated jets. In this work, a representative engine flow path is constructed using experimentally verified geometries to simulate the physics of core noise. A combustor, single-stage turbine, nozzle and jet are modeled in separate calculations using appropriate high fidelity techniques including LES, actuator disk theory and Ffowcs-Williams Hawkings surfaces. A one way coupling procedure is developed for passing fluctuations downstream through the flowpath. This method effectively isolates the core noise from other acoustic sources, enables straightforward study of the interaction between core noise and jet exhaust, and allows for simple distinction between direct and indirect noise. The impact of core noise on the farfield jet acoustics is studied extensively and the relative efficiency of different disturbance types and shapes is examined in detail.

  2. Improving Gabor Noise

    OpenAIRE

    Lagae, Ares; Lefebvre, Sylvain; Dutré, Philip

    2011-01-01

    We have recently proposed a new procedural noise function, Gabor noise, which offers a combination of properties not found in existing noise functions. In this paper, we present three significant improvements to Gabor noise: (1) an isotropic kernel for Gabor noise, which speeds up isotropic Gabor noise with a factor of roughly two, (2) an error analysis of Gabor noise, which relates the kernel truncation radius to the relative error of the noise, and (3) spatially varying Gabor noise, which e...

  3. Variable Geometry Aircraft Pylon Structure and Related Operation Techniques

    Science.gov (United States)

    Shah, Parthiv N. (Inventor)

    2014-01-01

    An aircraft control structure can be utilized for purposes of drag management, noise control, or aircraft flight maneuvering. The control structure includes a high pressure engine nozzle, such as a bypass nozzle or a core nozzle of a turbofan engine. The nozzle exhausts a high pressure fluid stream, which can be swirled using a deployable swirl vane architecture. The control structure also includes a variable geometry pylon configured to be coupled between the nozzle and the aircraft. The variable geometry pylon has a moveable pylon section that can be deployed into a deflected state to maintain or alter a swirling fluid stream (when the swirl vane architecture is deployed) for drag management purposes, or to assist in the performance of aircraft flight maneuvers.

  4. Aircraft Fire Protection Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Navy Aircraft Protection Laboratory provides complete test support for all Navy air vehicle fire protection systems. The facility allows for the simulation of a...

  5. Solar thermal aircraft

    Science.gov (United States)

    Bennett, Charles L.

    2007-09-18

    A solar thermal powered aircraft powered by heat energy from the sun. A heat engine, such as a Stirling engine, is carried by the aircraft body for producing power for a propulsion mechanism, such as a propeller. The heat engine has a thermal battery in thermal contact with it so that heat is supplied from the thermal battery. A solar concentrator, such as reflective parabolic trough, is movably connected to an optically transparent section of the aircraft body for receiving and concentrating solar energy from within the aircraft. Concentrated solar energy is collected by a heat collection and transport conduit, and heat transported to the thermal battery. A solar tracker includes a heliostat for determining optimal alignment with the sun, and a drive motor actuating the solar concentrator into optimal alignment with the sun based on a determination by the heliostat.

  6. Depreciation of aircraft

    Science.gov (United States)

    Warner, Edward P

    1922-01-01

    There is a widespread, and quite erroneous, impression to the effect that aircraft are essentially fragile and deteriorate with great rapidity when in service, so that the depreciation charges to be allowed on commercial or private operation are necessarily high.

  7. Aircraft electromagnetic compatibility

    Science.gov (United States)

    Clarke, Clifton A.; Larsen, William E.

    1987-01-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  8. Application of powered lift and mechanical flap concepts for civil short-haul transport aircraft design

    Science.gov (United States)

    Conlon, J. A.; Bowles, J. V.

    1977-01-01

    The objective of this paper is to determine various design and performance parameters, including wing loading and thrust loading requirements, for powered-lift and mechanical flap conceptual aircraft constrained by field length and community noise impact. Mission block fuel and direct operating costs (DOC) were found for optimum designs. As a baseline, the design and performance parameters were determined for the aircraft using engines without noise suppression. The constraint of the 90 EPNL noise contour being less than 2.6 sq km (1.0 sq mi) in area was then imposed. The results indicate that for both aircraft concepts the design gross weight, DOC, and required mission block fuel decreased with field length. At field lengths less than 1100 m (3600 ft) the powered lift aircraft had lower DOC and block fuel than the mechanical flap aircraft but produced higher unsuppressed noise levels. The noise goal could easily be achieved with nacelle wall treatment only and thus resulted in little or no performance or weight penalty for all studied aircraft.

  9. Relativistic Noise

    OpenAIRE

    Kapusta, Joseph; Mueller, Berndt; Stephanov, Misha

    2012-01-01

    The relativistic theory of hydrodynamic fluctuations, or noise, is derived and applied to high energy heavy ion collisions. These fluctuations are inherent in any space-time varying system and are in addition to initial state fluctuations. We illustrate the effects with the boost-invariant Bjorken solution to the hydrodynamic equations. Long range correlations in rapidity are induced by propagation of sound modes. The magnitude of these correlations are directly proportional to the viscositie...

  10. Skewed Noise

    OpenAIRE

    David Dillenberger; Uzi Segal

    2013-01-01

    Experimental evidence suggests that individuals who face an asymmetric distribution over the likelihood of a specific event might actually prefer not to know the exact value of this probability. We address these findings by studying a decision maker who has recursive, non-expected utility preferences over two-stage lotteries. For a binary lottery that yields the better outcome with probability p, we identify noise around p with a compound lottery that induces a probability distribution over t...

  11. Review of evolving trends in blended wing body aircraft design

    Science.gov (United States)

    Okonkwo, Paul; Smith, Howard

    2016-04-01

    The desire to produce environmentally friendly aircraft that is aerodynamically efficient and capable of conveying large number of passengers over long ranges at reduced direct operating cost led aircraft designers to develop the Blended Wing Body (BWB) aircraft concept. The BWB aircraft represents a paradigm shift in the design of aircraft. The design provides aerodynamics and environmental benefits and is suitable for the integration of advanced systems and concepts like laminar flow technology, jet flaps and distributed propulsion. However, despite these benefits, the BWB is yet to be developed for commercial air transport due to several challenges. This paper reviews emerging trends in BWB aircraft design highlighting design challenges that have hindered the development of a BWB passenger transport aircraft. The study finds that in order to harness the advantages and reduce the deficiencies of a tightly coupled configuration like the BWB, a multidisciplinary design synthesis optimisation should be conducted with good handling and ride quality as objective functions within acceptable direct operating cost and noise bounds.

  12. Aircraft Data Acquisition

    Directory of Open Access Journals (Sweden)

    Elena BALMUS

    2016-03-01

    Full Text Available The introduction of digital systems instead of analog ones has created a major separation in the aviation technology. Although the digital equipment made possible that the increasingly faster controllers take over, we should say that the real world remains essentially analogue [4]. Fly-by-wire designers attempting to control and measure the real feedback of an aircraft were forced to find a way to connect the analogue environment to their digital equipment. In order to manage the implications of this division in aviation, data optimization and comparison has been quite an important task. The interest in using data acquisition boards is being driven by the technology and design standards in the new generation of aircraft and the ongoing efforts of reducing weight and, in some cases addressing the safety risks. This paper presents a sum of technical report data from post processing and diversification of data acquisition from Arinc 429 interface on a research aircraft platform. Arinc 429 is by far the most common data bus in use on civil transport aircraft, regional jets and executive business jets today. Since its introduction on the Boeing 757/767 and Airbus aircraft in the early 1980s hardly any aircraft has been produced without the use of this data bus. It was used widely by the air transport indu

  13. Landing Gear Door Liners for Airframe Noise Reduction

    Science.gov (United States)

    Jones, Michael G. (Inventor); Howerton, Brian M. (Inventor); Van De Ven, Thomas (Inventor)

    2014-01-01

    A landing gear door for retractable landing gear of aircraft includes an acoustic liner. The acoustic liner includes one or more internal cavities or chambers having one or more openings that inhibit the generation of sound at the surface and/or absorb sound generated during operation of the aircraft. The landing gear door may include a plurality of internal chambers having different geometries to thereby absorb broadband noise.

  14. Active noise control using noise source having adaptive resonant frequency tuning through stress variation

    Science.gov (United States)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor); Renshaw, Anthony A. (Inventor); Hedeen, Robert A. (Inventor)

    1995-01-01

    A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by an expandable ring embedded in the noise radiating element. Excitation of the ring causes expansion or contraction of the ring, thereby varying the stress in the noise radiating element. The ring is actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the ring, causing the ring to expand or contract. Instead of a single ring embedded in the noise radiating panel, a first expandable ring can be bonded to one side of the noise radiating element, and a second expandable ring can be bonded to the other side.

  15. Cardiovascular effects of environmental noise: Research in Germany

    Directory of Open Access Journals (Sweden)

    Christian Maschke

    2011-01-01

    Full Text Available Research on systematic noise effects started in Germany back in the fifties with basic experimental studies on humans. As a result, noise was classified as a non-specific stressor, which could cause an ergotropic activation of the complete organism. In the light of this background research a hypothesis was proposed that long-term noise exposure could have an adverse effect on health. This hypothesis was further supported by animal studies. Since the sixties, the adverse effects of chronic road traffic noise exposure were further examined in humans with the help of epidemiological studies. More epidemiological aircraft noise studies followed in the 1970s and thereafter. The sample size was increased, relevant confounding factors were taken into account, and the exposure and health outcomes were investigated objectively and with higher quality measures. To date, more than 20 German epidemiological traffic noise studies have focused on noise-induced health effects, mainly on the cardiovascular system. In particular, the newer German noise studies demonstrate a clear association between residential exposure to traffic noise (particularly night noise and cardiovascular outcomes. Nevertheless, additional research is needed, particularly on vulnerable groups and multiple noise exposures. The epidemiological findings have still not been fully considered in German regulations, particularly for aircraft noise. The findings, however, were taken into account in national recommendations. The Federal Environment Agency recommends noise rating levels of 65 dB(A for the day and 55 dB(A for the night, as a short-term goal. In the medium term, noise rating levels of 60 / 50 (day, night should be reached and noise rating levels of 55 / 45 in the long run.

  16. Cardiovascular effects of environmental noise: Research in Sweden

    Directory of Open Access Journals (Sweden)

    Gösta Bluhm

    2011-01-01

    Full Text Available In Sweden, as in many other European countries, traffic noise is an important environmental health issue. At present, almost two million people are exposed to average noise levels exceeding the outdoor national guideline value (55 dB(A. Despite efforts to reduce the noise burden, noise-related health effects, such as annoyance and sleep disturbances, are increasing. The scientific interest regarding more serious health effects related to the cardiovascular system is growing, and several experimental and epidemiological studies have been performed or are ongoing. Most of the studies on cardiovascular outcomes have been related to noise from road or aircraft traffic. Few studies have included railway noise. The outcomes under study include morning saliva cortisol, treatment for hypertension, self-reported hypertension, and myocardial infarction. The Swedish studies on road traffic noise support the hypothesis of an association between long-term noise exposure and cardiovascular disease. However, the magnitude of effect varies between the studies and has been shown to depend on factors such as sex, number of years at residence, and noise annoyance. Two national studies have been performed on the cardiovascular effects of aircraft noise exposure. The first one, a cross-sectional study assessing self-reported hypertension, has shown a 30% risk increase per 5 dB(A noise increase. The second one, which to our knowledge is the first longitudinal study assessing the cumulative incidence of hypertension, found a relative risk (RR of 1.10 (95% CI 1.01 - 1.19 per 5 dB(A noise increase. No associations have been found between railway noise and cardiovascular diseases. The findings regarding noise-related health effects and their economic consequences should be taken into account in future noise abatement policies and community planning.

  17. Noise in Optical Amplifiers

    DEFF Research Database (Denmark)

    Jeppesen, Palle

    1997-01-01

    Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived.......Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived....

  18. Low noise road surfaces

    OpenAIRE

    Bolčina, Matjaž

    2014-01-01

    Noise is everywhere. Noise is a sound that makes people stressful and irritate. It often couses sleep disorders and also health problems like different cardiovascular disorders, hearing loss…In most cases traffic noise is the most disturbing. There are different ways to prevent people from traffic noise like building noise barriers and insulation of facades. However noise barriers and insulation of facades do not prevent noise formation, but are lowering existing noise. Another disadvantage i...

  19. Enhanced Fan Noise Modeling for Turbofan Engines

    Science.gov (United States)

    Krejsa, Eugene A.; Stone, James R.

    2014-01-01

    This report describes work by consultants to Diversitech Inc. for the NASA Glenn Research Center (GRC) to revise the fan noise prediction procedure based on fan noise data obtained in the 9- by 15 Foot Low-Speed Wind Tunnel at GRC. The purpose of this task is to begin development of an enhanced, analytical, more physics-based, fan noise prediction method applicable to commercial turbofan propulsion systems. The method is to be suitable for programming into a computational model for eventual incorporation into NASA's current aircraft system noise prediction computer codes. The scope of this task is in alignment with the mission of the Propulsion 21 research effort conducted by the coalition of NASA, state government, industry, and academia to develop aeropropulsion technologies. A model for fan noise prediction was developed based on measured noise levels for the R4 rotor with several outlet guide vane variations and three fan exhaust areas. The model predicts the complete fan noise spectrum, including broadband noise, tones, and for supersonic tip speeds, combination tones. Both spectra and directivity are predicted. Good agreement with data was achieved for all fan geometries. Comparisons with data from a second fan, the ADP fan, also showed good agreement.

  20. Validated Design and Analysis Tool for Small Vertical-Lift Unmanned Air Vehicle Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A procedure and supporting computer code for the prediction of noise that radiates from small, vertical lift UAV aircraft is proposed. The resulting building block...

  1. Unstructured, High-Order Scheme Module with Low Dissipation Flux Difference Splitting for Noise Prediction Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thorough understanding of aircraft airframe and engine noise mechanisms and the subsequent acoustic propagation to the farfield is necessary to develop and evaluate...

  2. Passive Techniques for Fan Noise Reduction in New Turbofan Engines: Review

    OpenAIRE

    M.Gorj-Bandpy; M. Azimi

    2013-01-01

    Among the various environmental concerns, the aircraft noise item has been constantly growing in importance over the past years. Measures for its reduction at the source as well its mitigation around airports must take into account aspects of medicine and technical design as well as legal and land use planning aspects. Fan noise is one of the principal noise sources in turbofan aero-engines. In this paper a review of the main technologies employed for the reduction of fan noise turbo...

  3. The Effect of Transportation Noise on Health and Cognitive Development:A Review of Recent Evidence

    OpenAIRE

    Clark, Charlotte; Stansfeld, Stephen A

    2007-01-01

    Noise from transport is an increasingly prominent feature of the urban environment. Whilst the auditory effects of noise on humans are established, non-auditory effects - the effects of noise exposure on human health, well-being and cognitive development - are less well established. This narrative review evaluates recent studies of aircraft and road traffic noise that have advanced or synthesized knowledge about several aspects of adult and child health and cognition. Studies have demonstrate...

  4. Nocturnal air, road, and rail traffic noise and daytime cognitive performance and annoyance

    OpenAIRE

    Elmenhorst, E.-M.; Quehl, J.; U. Müller; Basner, M.

    2014-01-01

    Various studies indicate that at the same noise level and during the daytime, annoyance increases in the order of rail, road, and aircraft noise. The present study investigates if the same ranking can be found for annoyance to nocturnal exposure and next day cognitive performance. Annoyance ratings and performance change during combined noise exposure were also tested. In the laboratory 72 participants were exposed to air, road, or rail traffic noise and all combinations. The numb...

  5. IDENTIFICATION OF AIRCRAFT HAZARDS

    International Nuclear Information System (INIS)

    Aircraft hazards were determined to be potentially applicable to a repository at Yucca Mountain in the ''Monitored Geological Repository External Events Hazards Screening Analysis'' (BSC 2004, Section 6.4.1). That determination was conservatively based on limited knowledge of flight data in the area of concern and on crash data for aircraft of the type flying near Yucca Mountain. The purpose of this report is to identify specific aircraft hazards that may be applicable to a Monitored Geologic Repository (MGR) at Yucca Mountain using NUREG-0800, ''Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants'' (NRC 1987, Section 3.5.1.6), as guidance for the inclusion or exclusion of identified aircraft hazards. NUREG-0800 is being used here as a reference because some of the same considerations apply. The intended use of this report is to provide inputs for further screening and analysis of the identified aircraft hazards based on the criteria that apply to Category 1 and 2 event sequence analyses as defined in 10 CFR 63.2 (see Section 4). The scope of this technical report includes the evaluation of military, private, and commercial use of airspace in the 100-mile regional setting of the MGR at Yucca Mountain with the potential for reducing the regional setting to a more manageable size after consideration of applicable screening criteria (see Section 7)

  6. Aircraft Operations Classification System

    Science.gov (United States)

    Harlow, Charles; Zhu, Weihong

    2001-01-01

    Accurate data is important in the aviation planning process. In this project we consider systems for measuring aircraft activity at airports. This would include determining the type of aircraft such as jet, helicopter, single engine, and multiengine propeller. Some of the issues involved in deploying technologies for monitoring aircraft operations are cost, reliability, and accuracy. In addition, the system must be field portable and acceptable at airports. A comparison of technologies was conducted and it was decided that an aircraft monitoring system should be based upon acoustic technology. A multimedia relational database was established for the study. The information contained in the database consists of airport information, runway information, acoustic records, photographic records, a description of the event (takeoff, landing), aircraft type, and environmental information. We extracted features from the time signal and the frequency content of the signal. A multi-layer feed-forward neural network was chosen as the classifier. Training and testing results were obtained. We were able to obtain classification results of over 90 percent for training and testing for takeoff events.

  7. Identification of Aircraft Hazards

    International Nuclear Information System (INIS)

    Aircraft hazards were determined to be potentially applicable to a repository at Yucca Mountain in ''Monitored Geological Repository External Events Hazards Screening Analysis'' (BSC 2005 [DIRS 174235], Section 6.4.1). That determination was conservatively based upon limited knowledge of flight data in the area of concern and upon crash data for aircraft of the type flying near Yucca Mountain. The purpose of this report is to identify specific aircraft hazards that may be applicable to a monitored geologic repository (MGR) at Yucca Mountain, using NUREG-0800, ''Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants'' (NRC 1987 [DIRS 103124], Section 3.5.1.6), as guidance for the inclusion or exclusion of identified aircraft hazards. The intended use of this report is to provide inputs for further screening and analysis of identified aircraft hazards based upon the criteria that apply to Category 1 and Category 2 event sequence analyses as defined in 10 CFR 63.2 [DIRS 176544] (Section 4). The scope of this report includes the evaluation of military, private, and commercial use of airspace in the 100-mile regional setting of the repository at Yucca Mountain with the potential for reducing the regional setting to a more manageable size after consideration of applicable screening criteria (Section 7)

  8. IDENTIFICATION OF AIRCRAFT HAZARDS

    Energy Technology Data Exchange (ETDEWEB)

    K.L. Ashley

    2005-03-23

    Aircraft hazards were determined to be potentially applicable to a repository at Yucca Mountain in the ''Monitored Geological Repository External Events Hazards Screening Analysis'' (BSC 2004, Section 6.4.1). That determination was conservatively based on limited knowledge of flight data in the area of concern and on crash data for aircraft of the type flying near Yucca Mountain. The purpose of this report is to identify specific aircraft hazards that may be applicable to a Monitored Geologic Repository (MGR) at Yucca Mountain using NUREG-0800, ''Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants'' (NRC 1987, Section 3.5.1.6), as guidance for the inclusion or exclusion of identified aircraft hazards. NUREG-0800 is being used here as a reference because some of the same considerations apply. The intended use of this report is to provide inputs for further screening and analysis of the identified aircraft hazards based on the criteria that apply to Category 1 and 2 event sequence analyses as defined in 10 CFR 63.2 (see Section 4). The scope of this technical report includes the evaluation of military, private, and commercial use of airspace in the 100-mile regional setting of the MGR at Yucca Mountain with the potential for reducing the regional setting to a more manageable size after consideration of applicable screening criteria (see Section 7).

  9. Identification of Aircraft Hazards

    Energy Technology Data Exchange (ETDEWEB)

    K. Ashley

    2006-12-08

    Aircraft hazards were determined to be potentially applicable to a repository at Yucca Mountain in ''Monitored Geological Repository External Events Hazards Screening Analysis'' (BSC 2005 [DIRS 174235], Section 6.4.1). That determination was conservatively based upon limited knowledge of flight data in the area of concern and upon crash data for aircraft of the type flying near Yucca Mountain. The purpose of this report is to identify specific aircraft hazards that may be applicable to a monitored geologic repository (MGR) at Yucca Mountain, using NUREG-0800, ''Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants'' (NRC 1987 [DIRS 103124], Section 3.5.1.6), as guidance for the inclusion or exclusion of identified aircraft hazards. The intended use of this report is to provide inputs for further screening and analysis of identified aircraft hazards based upon the criteria that apply to Category 1 and Category 2 event sequence analyses as defined in 10 CFR 63.2 [DIRS 176544] (Section 4). The scope of this report includes the evaluation of military, private, and commercial use of airspace in the 100-mile regional setting of the repository at Yucca Mountain with the potential for reducing the regional setting to a more manageable size after consideration of applicable screening criteria (Section 7).

  10. Jet Engine Noise Generation, Prediction and Control. Chapter 86

    Science.gov (United States)

    Huff, Dennis L.; Envia, Edmane

    2004-01-01

    Aircraft noise has been a problem near airports for many years. It is a quality of life issue that impacts millions of people around the world. Solving this problem has been the principal goal of noise reduction research that began when commercial jet travel became a reality. While progress has been made in reducing both airframe and engine noise, historically, most of the aircraft noise reduction efforts have concentrated on the engines. This was most evident during the 1950 s and 1960 s when turbojet engines were in wide use. This type of engine produces high velocity hot exhaust jets during takeoff generating a great deal of noise. While there are fewer commercial aircraft flying today with turbojet engines, supersonic aircraft including high performance military aircraft use engines with similar exhaust flow characteristics. The Pratt & Whitney F100-PW-229, pictured in Figure la, is an example of an engine that powers the F-15 and F-16 fighter jets. The turbofan engine was developed for subsonic transports, which in addition to better fuel efficiency also helped mitigate engine noise by reducing the jet exhaust velocity. These engines were introduced in the late 1960 s and power most of the commercial fleet today. Over the years, the bypass ratio (that is the ratio of the mass flow through the fan bypass duct to the mass flow through the engine core) has increased to values approaching 9 for modern turbofans such as the General Electric s GE-90 engine (Figure lb). The benefits to noise reduction for high bypass ratio (HPBR) engines are derived from lowering the core jet velocity and temperature, and lowering the tip speed and pressure ratio of the fan, both of which are the consequences of the increase in bypass ratio. The HBPR engines are typically very large in diameter and can produce over 100,000 pounds of thrust for the largest engines. A third type of engine flying today is the turbo-shaft which is mainly used to power turboprop aircraft and helicopters

  11. Nonequilibrium Spin Noise and Noise of Susceptibility

    OpenAIRE

    Schad, Pablo; Narozhny, Boris N.; Schön, Gerd; Shnirman, Alexander

    2014-01-01

    We analyze out-of-equilibrium fluctuations in a driven spin system and relate them to the noise of spin susceptibility. In the spirit of the linear response theory we further relate the noise of susceptibility to a $4$-spin correlation function in equilibrium. We show that, in contrast to the second noise (noise of noise), the noise of susceptibility is a direct measure of non-Gaussian fluctuations in the system. We develop a general framework for calculating the noise of susceptibility using...

  12. Active noise control for high frequencies

    OpenAIRE

    Kaymak, E; Atherton, MA; Rotter, KRG; Millar, B.

    2006-01-01

    There are many applications that can benefit from Active Noise Control (ANC) such as in aircraft cabins and air conditioning ducts, i.e. in situations where technology interferes with human hearing in a harmful way or disrupts communication. Headsets with analogue ANC circuits have been used in the armed forces for attenuating frequencies below 1 kHz, which when combined with passive filtering offers protection across the whole frequency range of human hearing. A dental surgery is also a nois...

  13. Forward Looking Radar Imaging by Truncated Singular Value Decomposition and Its Application for Adverse Weather Aircraft Landing

    OpenAIRE

    Yulin Huang; Yuebo Zha; Yue Wang; Jianyu Yang

    2015-01-01

    The forward looking radar imaging task is a practical and challenging problem for adverse weather aircraft landing industry. Deconvolution method can realize the forward looking imaging but it often leads to the noise amplification in the radar image. In this paper, a forward looking radar imaging based on deconvolution method is presented for adverse weather aircraft landing. We first present the theoretical background of forward looking radar imaging task and its application for aircraft la...

  14. Preliminary design studies of an advanced general aviation aircraft

    Science.gov (United States)

    Barrett, Ron; Demoss, Shane; Dirkzwager, AB; Evans, Darryl; Gomer, Charles; Keiter, Jerry; Knipp, Darren; Seier, Glen; Smith, Steve; Wenninger, ED

    1991-01-01

    The preliminary design results are presented of the advanced aircraft design project. The goal was to take a revolutionary look into the design of a general aviation aircraft. Phase 1 of the project included the preliminary design of two configurations, a pusher, and a tractor. Phase 2 included the selection of only one configuration for further study. The pusher configuration was selected on the basis of performance characteristics, cabin noise, natural laminar flow, and system layouts. The design was then iterated to achieve higher levels of performance.

  15. Voice communications in the cockpit noise environment: The role of active noise reduction

    Science.gov (United States)

    Wheeler, Peter David

    The topic of voice communications in the cockpit noise environment of modern fast-jet aircraft and helicopters is addressed, and in particular, research undertaken in support of the development of a system for reducing the noise level at the operators' ear is described by acoustic cancellation within the ear defender, known as active noise reduction (ANR). The internal noise spectra of today's high performance fast-jet aircraft and military helicopters is described, and the complex interaction of acoustic noise transmission, speech, and microphone noise pick-up, which produces the total acoustic environment at the aircrews' ears, is discussed. Means of mathematically modelling the audio channel, quantifying the components identified above, and identifying areas of shortfall in performance are derived, leading to a procedure for the development of attenuation requirements, described as the communications audit. A model of the electroacoustic characteristics of the ANR ear defender assembly is presented and the sound field distribution within the ear defender/ear cavity, and its effect upon cancellation performance, is discussed. The extensive laboratory and flight testing of the ANR system that was undertaken is reviewed, paying particular attention to the measurement and analysis techniques employed in such testing. Finally, the performance characteristics of ANR are discussed and compared with the requirements previously established. Design limitations placed upon the system by the constraints of its area of application are described, and the scope for future improvements is considered.

  16. Active noise control using noise source having adaptive resonant frequency tuning through variable ring loading

    Science.gov (United States)

    Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor); Renshaw, Anthony A. (Inventor); Hedeen, Robert A. (Inventor)

    1995-01-01

    A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of noise radiating structure is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating structure is tuned by a plurality of drivers arranged to contact the noise radiating structure. Excitation of the drivers causes expansion or contraction of the drivers, thereby varying the edge loading applied to the noise radiating structure. The drivers are actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the drivers, causing them to expand or contract. The noise radiating structure may be either the outer shroud of the engine or a ring mounted flush with an inner wall of the shroud or disposed in the interior of the shroud.

  17. Advanced Aircraft Material

    Directory of Open Access Journals (Sweden)

    Vivek Kumar Prince

    2013-06-01

    Full Text Available There has been long debate on “advanced aircraft material” from past decades & researchers too came out with lots of new advanced material like composites and different aluminum alloys. Now days a new advancement that is in great talk is third generation Aluminum-lithium alloy. Newest Aluminum-lithium alloys are found out to have low density, higher elastic modulus, greater stiffness, greater cryogenic toughness, high resistance to fatigue cracking and improved corrosion resistance properties over the earlier used aircraft material as mentioned in Table 3 [1-5]. Comparison had been made with nowadays used composite material and is found out to be more superior then that

  18. Research Plans for Improving Understanding of Effects of Very Low-Frequency Noise of Heavy Lift Rotorcraft

    Science.gov (United States)

    Fidell, Sanford; Horonieff, Richard D.; Schmitz, Fredric H.

    2010-01-01

    This report reviews the English-language technical literature on infrasonic and low-frequency noise effects; identifies the most salient effects of noise produced by a future large civil tiltrotor aircraft on crew, passengers, and communities near landing areas; and recommends research needed to improve understanding of the effects of such noise on passengers, crew, and residents of areas near landing pads.

  19. Enhanced Core Noise Modeling for Turbofan Engines

    Science.gov (United States)

    Stone, James R.; Krejsa, Eugene A.; Clark, Bruce J.

    2011-01-01

    This report describes work performed by MTC Technologies (MTCT) for NASA Glenn Research Center (GRC) under Contract NAS3-00178, Task Order No. 15. MTCT previously developed a first-generation empirical model that correlates the core/combustion noise of four GE engines, the CF6, CF34, CFM56, and GE90 for General Electric (GE) under Contract No. 200-1X-14W53048, in support of GRC Contract NAS3-01135. MTCT has demonstrated in earlier noise modeling efforts that the improvement of predictive modeling is greatly enhanced by an iterative approach, so in support of NASA's Quiet Aircraft Technology Project, GRC sponsored this effort to improve the model. Since the noise data available for correlation are total engine noise spectra, it is total engine noise that must be predicted. Since the scope of this effort was not sufficient to explore fan and turbine noise, the most meaningful comparisons must be restricted to frequencies below the blade passage frequency. Below the blade passage frequency and at relatively high power settings jet noise is expected to be the dominant source, and comparisons are shown that demonstrate the accuracy of the jet noise model recently developed by MTCT for NASA under Contract NAS3-00178, Task Order No. 10. At lower power settings the core noise became most apparent, and these data corrected for the contribution of jet noise were then used to establish the characteristics of core noise. There is clearly more than one spectral range where core noise is evident, so the spectral approach developed by von Glahn and Krejsa in 1982 wherein four spectral regions overlap, was used in the GE effort. Further analysis indicates that the two higher frequency components, which are often somewhat masked by turbomachinery noise, can be treated as one component, and it is on that basis that the current model is formulated. The frequency scaling relationships are improved and are now based on combustor and core nozzle geometries. In conjunction with the Task

  20. Long Range Aircraft Trajectory Prediction

    OpenAIRE

    Magister, Tone

    2009-01-01

    The subject of the paper is the improvement of the aircraft future trajectory prediction accuracy for long-range airborne separation assurance. The strategic planning of safe aircraft flights and effective conflict avoidance tactics demand timely and accurate conflict detection based upon future four–dimensional airborne traffic situation prediction which is as accurate as each aircraft flight trajectory prediction. The improved kinematics model of aircraft relative flight considering flight ...

  1. Active Fluid Borne Noise Reduction for Aviation Hydraulic Pumps

    OpenAIRE

    Waitschat, Arne; Thielecke, Frank; Behr, Robert M.; Heise, Ulrich

    2016-01-01

    The aviation environment holds challenging application constraints for efficient hydraulic system noise reduction devices. Besides strong limits on component weight and size, high safety and reliability standards demand simple solutions. Hence, basic silencers like inline expansion chambers and Helmholtz-Resonators are state-of-the-art aboard commercial aircrafts. Unfortunately, they do not meet today’s noise attenuation aims regarding passenger comfort and equipment durability. Significant a...

  2. Analytical developments for definition and prediction of USB noise

    Science.gov (United States)

    Reddy, N. N.; Tam, C. K. W.

    1976-01-01

    A systematic acoustic data base and associated flow data are used in identifying the noise generating mechanisms of upper surface blown flap configurations of short takeoff and landing aircraft. Theory is developed for the radiated sound field of the highly sheared flow of the trailing edge wake. An empirical method is also developed using extensive experimental data and physical reasonings to predict the noise levels.

  3. Contributions to the optimisation of aircraft noise abatement procedures

    OpenAIRE

    Prats i Menéndez, Xavier

    2011-01-01

    Tot i que en les últimes dècades la reducció del soroll emès pels avions ha estat substancial, el seu impacte a la població ubicada a prop dels aeroports és un problema que encara persisteix. Contenir el soroll generat per les operacions d'aeronaus, tot assumint al mateix temps la creixent demanda de vols, és un dels principals desafiaments a que s'enfronten les autoritats aeroportuàries, els proveïdors de serveis per a la navegació aèria i els operadors de les aeronaus. A part de millorar ...

  4. Robots for Aircraft Maintenance

    Science.gov (United States)

    1993-01-01

    Marshall Space Flight Center charged USBI (now Pratt & Whitney) with the task of developing an advanced stripping system based on hydroblasting to strip paint and thermal protection material from Space Shuttle solid rocket boosters. A robot, mounted on a transportable platform, controls the waterjet angle, water pressure and flow rate. This technology, now known as ARMS, has found commercial applications in the removal of coatings from jet engine components. The system is significantly faster than manual procedures and uses only minimal labor. Because the amount of "substrate" lost is minimal, the life of the component is extended. The need for toxic chemicals is reduced, as is waste disposal and human protection equipment. Users of the ARMS work cell include Delta Air Lines and the Air Force, which later contracted with USBI for development of a Large Aircraft Paint Stripping system (LARPS). LARPS' advantages are similar to ARMS, and it has enormous potential in military and civil aircraft maintenance. The technology may also be adapted to aircraft painting, aircraft inspection techniques and paint stripping of large objects like ships and railcars.

  5. Inhibitory noise

    Directory of Open Access Journals (Sweden)

    Alain Destexhe

    2010-03-01

    Full Text Available Cortical neurons in vivo may operate in high-conductance states, in which the major part of the neuron's input conductance is due to synaptic activity, sometimes several-fold larger than the resting conductance. We examine here the contribution of inhibition in such high-conductance states. At the level of the absolute conductance values, several studies have shown that cortical neurons in vivo are characterized by strong inhibitory conductances. However, conductances are balanced and spiking activity is mostly determined by fluctuations, but not much is known about excitatory and inhibitory contributions to these fluctuations. Models and dynamic-clamp experiments show that, during high-conductance states, spikes are mainly determined by fluctuations of inhibition, or by inhibitory noise. This stands in contrast to low-conductance states, in which excitatory conductances determine spiking activity. To determine these contributions from experimental data, maximum likelihood methods can be designed and applied to intracellular recordings in vivo. Such methods indicate that action potentials are indeed mostly correlated with inhibitory fluctuations in awake animals. These results argue for a determinant role for inhibitory fluctuations in evoking spikes, and do not support feed-forward modes of processing, for which opposite patterns are predicted.

  6. Braking performance of aircraft tires

    Science.gov (United States)

    Agrawal, Satish K.

    This paper brings under one cover the subject of aircraft braking performance and a variety of related phenomena that lead to aircraft hydroplaning, overruns, and loss of directional control. Complex processes involving tire deformation, tire slipping, and fluid pressures in the tire-runway contact area develop the friction forces for retarding the aircraft; this paper describes the physics of these processes. The paper reviews the past and present research efforts and concludes that the most effective way to combat the hazards associated with aircraft landings and takeoffs on contaminated runways is by measuring and displaying in realtime the braking performance parameters in the aircraft cockpit.

  7. Airport noise predicts song timing of European birds.

    Science.gov (United States)

    Dominoni, Davide M; Greif, Stefan; Nemeth, Erwin; Brumm, Henrik

    2016-09-01

    Anthropogenic noise is of increasing concern to biologists and medical scientists. Its detrimental effects on human health have been well studied, with the high noise levels from air traffic being of particular concern. However, less is known about the effects of airport noise pollution on signal masking in wild animals. Here, we report a relationship between aircraft noise and two major features of the singing behavior of birds. We found that five of ten songbird species began singing significantly earlier in the morning in the vicinity of a major European airport than their conspecifics at a quieter control site. As birds at both sites started singing before the onset of air traffic in the morning, this suggests that the birds in the vicinity of the airport advanced their activity to gain more time for unimpaired singing before the massive plane noise set in. In addition, we found that during the day, chaffinches avoided singing during airplane takeoffs, but only when the noise exceeded a certain threshold, further suggesting that the massive noise caused by the airport can impair acoustic communication in birds. Overall, our study indicates that birds may be adjusting their mating signals and time budgets in response to aircraft noise. PMID:27648232

  8. Cardiovascular effects of environmental noise: Research in the United Kingdom

    Directory of Open Access Journals (Sweden)

    Stephen Stansfeld

    2011-01-01

    Full Text Available Although the auditory effects of noise on humans have been established, the non-auditory effects are not so well established. The emerging links between noise and cardiovascular disease (CVD have potentially important implications on public health and policy. In the United Kingdom (UK, noise from transport is a problem, where more than half of the population is exposed to more than the recommended maximum day-time noise level and just under three-quarters of the population live in areas where the recommended night-time noise level is exceeded. This review focuses on findings from studies conducted in the UK that examined environmental noise and cardiovascular disease. There were statistically no significant associations between road traffic noise and incident ischemic heart disease in the Caerphilly and Speedwell studies, but there was a suggestion of effects when modifying factors such as length of residence, room orientation, and window opening were taken into account. In a sample stratified by pre-existing disease a strongly increased odds of incident ischemic heart disease for the highest annoyance category was found compared to the lowest among men without pre-existing disease (OR = 2.45, 95%1.13 - 5.31, which was not found in men with pre-existing disease. In the Hypertension and exposure to noise near airports (HYENA study, night time aircraft noise exposure (L night was associated with an increased risk of hypertension, in fully adjusted analyses. A 10-dB increase in aircraft noise exposure was associated with an odds ratio of 1.14 (95%CI, 1.01 - 1.29. Aircraft noise was not consistently related to raised systolic blood pressure in children in the road traffic and aircraft noise exposure and children′s cognition and health (RANCH study. There is some evidence of an association among environmental noise exposure and hypertension and ischemic heart disease in the UK studies; further studies are required to explore gender differences, the

  9. Noise and Hearing Protection

    Science.gov (United States)

    ... Meeting Calendar Find an ENT Doctor Near You Noise and Hearing Protection Noise and Hearing Protection Patient ... it is. How can I tell if a noise is dangerous? People differ in their sensitivity to ...

  10. Interference Cancellation in Aircraft Cockpit by Adaptive Filters

    Directory of Open Access Journals (Sweden)

    Arun C.

    2016-01-01

    Full Text Available This paper investigates on the development and implementation of adaptive noise cancellation (ANC algorithm meant for mitigating the high level engine noise in the cockpit of an aircraft, which makes the speech signal unintelligible. Adaptive filters configured as interference canceller have the potential application in mitigating the above interference. A comparative study of Gradient based adaptive Infinite Impulse Response (IIR algorithm and its modified version is performed using MATLAB simulator in terms of converging speed. From the simulation result the best IIR algorithm is used for implementation in Performance Optimized with Enhanced RISC PC (Power PC 7448.

  11. Noise-Measuring Method

    DEFF Research Database (Denmark)

    Diamond, J. M.

    1965-01-01

    A noise-measuring method based on the use of a calibrated noise generator and an output meter with a special scale is described. The method eliminates the effect of noise contributions occurring in the circuits following the device under test.......A noise-measuring method based on the use of a calibrated noise generator and an output meter with a special scale is described. The method eliminates the effect of noise contributions occurring in the circuits following the device under test....

  12. Development of composite aircraft components in INCDT COMOTI, Bucharest

    Directory of Open Access Journals (Sweden)

    Raluca VOICU

    2012-12-01

    Full Text Available This paper presents the recent research activities within INCDT COMOTI, in the composite materials field. The author makes a short introduction of this field and presents an example of application developed within the composite materials laboratory from INCDT COMOTI, targeting the aeronautic field. The aircraft component is a stator blade made of CFRP composites, integrating new active noise reduction technologies and manufactured by means of the autoclave technology.

  13. Development of a rating procedure for low frequency noise : Results of measurements near runways

    NARCIS (Netherlands)

    Buikema, E.; Vercammen, M.; Ploeg, F. van der; Granneman, J.; Vos, J.

    2010-01-01

    Recent issues concerning low frequency aircraft noise around airports (groundnoise) and a legal verdict about the application of low frequency noise criteria in the Netherlands have been the motivation to start a research commissioned by the Dutch Ministry of Housing, Spatial Planning and the Enviro

  14. Fuel Cell Airframe Integration Study for Short-Range Aircraft. Volume 1; Aircraft Propulsion and Subsystems Integration Evaluation

    Science.gov (United States)

    Gummalla, Mallika; Pandy, Arun; Braun, Robert; Carriere, Thierry; Yamanis, Jean; Vanderspurt, Thomas; Hardin, Larry; Welch, Rick

    2006-01-01

    The objective of this study is to define the functionality and evaluate the propulsion and power system benefits derived from a Solid Oxide Fuel Cell (SOFC) based Auxiliary Power Unit (APU) for a future short range commercial aircraft, and to define the technology gaps to enable such a system. United Technologies Corporation (UTC) Integrated Total Aircraft Power System (ITAPS) methodologies were used to evaluate a baseline aircraft and several SOFC architectures. The technology benefits were captured as reductions of the mission fuel burn, life cycle cost, noise and emissions. As a result of the study, it was recognized that system integration is critical to maximize benefits from the SOFC APU for aircraft application. The mission fuel burn savings for the two SOFC architectures ranged from 4.7 percent for a system with high integration to 6.7 percent for a highly integrated system with certain technological risks. The SOFC APU itself produced zero emissions. The reduction in engine fuel burn achieved with the SOFC systems also resulted in reduced emissions from the engines for both ground operations and in flight. The noise level of the baseline APU with a silencer is 78 dBA, while the SOFC APU produced a lower noise level. It is concluded that a high specific power SOFC system is needed to achieve the benefits identified in this study. Additional areas requiring further development are the processing of the fuel to remove sulfur, either on board or on the ground, and extending the heat sink capability of the fuel to allow greater waste heat recovery, resolve the transient electrical system integration issues, and identification of the impact of the location of the SOFC and its size on the aircraft.

  15. Measured Noise from Small Unmanned Aerial Vehicles

    Science.gov (United States)

    Cabell, Randolph; McSwain, Robert; Grosveld, Ferdinand

    2016-01-01

    Proposed uses of small unmanned aerial vehicles (UAVs), including home package delivery, have the potential to expose large portions of communities to a new noise source. This paper discusses results of flyover noise measurements of four small UAVs, including an internal combustion-powered model airplane and three battery-powered multicopters. Basic noise characteristics of these vehicles are discussed, including spectral properties and sound level metrics such as sound pressure level, effective perceived noise level, and sound exposure level. The size and aerodynamic characteristics of the multicopters in particular make their flight path susceptible to atmospheric disturbances such as wind gusts. These gusts, coupled with a flight control system that varies rotor speed to maintain vehicle stability, create an unsteady acoustic signature. The spectral variations resulting from this unsteadiness are explored, in both hover and flyover conditions for the multicopters. The time varying noise, which differs from the relatively steady noise generated by large transport aircraft, may complicate the prediction of human annoyance using conventional sound level metrics.

  16. Noise emitted from road, rail and air traffic and their effects on sleep

    Science.gov (United States)

    Griefahn, Barbara; Marks, Anke; Robens, Sibylle

    2006-08-01

    This study compared the effects of road, rail, and aircraft noise and tested the applicability of the equivalent noise level for the evaluation of sleep disturbances. Sixteen women and 16 men (19-28 years) slept during 3 consecutive weeks in the laboratory. Eight persons slept in quiet throughout. Twenty-four persons were exposed to road, rail, or aircraft noise with weekly permuted changes. Each week consisted of a random sequence of a quiet night (32 dBA) and 3 nights with equivalent noise levels of 39, 44, and 50 dBA and maximum levels of 50-62, 56-68, and 62-74 dBA, respectively. The polysomnogram was recorded during all nights, sleep quality was assessed and performance tests were completed in the morning. Subjectively evaluated sleep quality decreased and reaction time increased gradually with noise levels, whereas most physiological variables revealed the same reactions to both the lower and considerably stronger reactions to the highest noise load. Aircraft noise, rail and road traffic noise caused similar after-effects but physiological sleep parameters were most severely affected by rail noise. The equivalent noise level seems to be a suitable predictor for subjectively evaluated sleep quality but not for physiological sleep disturbances.

  17. 19 CFR 10.183 - Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components...

    Science.gov (United States)

    2010-04-01

    ... Duty-free entry of civil aircraft, aircraft engines, ground flight simulators, parts, components, and... aircraft, aircraft engines, and ground flight simulators, including their parts, components, and... United States (HTSUS) by meeting the following requirements: (1) The aircraft, aircraft engines,...

  18. Can Noise Kill People?

    Institute of Scientific and Technical Information of China (English)

    刘玲娣

    2007-01-01

    Someone is singing next door,but you feel unhappy because her singing is just making a noise.We know that too much noise makes people feel terrible. Scientists are still trying to find out more about noise,but already it is known that a noise of over 85 decibels can make some people tired and anxious.

  19. Immersion Into Noise

    OpenAIRE

    Nechvatal, Joseph

    2011-01-01

    Joseph Nechvatal's Immersion Into Noise investigates multiple aspects of cultural noise by applying our audio understanding of noise to the visual, architectual and cognative domains. The author takes the reader through phenomenal aspects of the art of noise into algorithmic and network contexts, beginning in the Abside of the Grotte de Lascaux.

  20. Noise, Health, and Architecture.

    Science.gov (United States)

    Beranek, Leo L.

    There is reasonable agreement that hearing impairment is related to noise exposure. This hearing loss due to noise is considered a serious health injury, but there is still difficulty in delineating the importance of noise related to people's general non-auditory well-being and health. Beside hearing loss, noise inhibits satisfactory speech…

  1. Does noise affect learning? A short review on noise effects on cognitive performance in children.

    Science.gov (United States)

    Klatte, Maria; Bergström, Kirstin; Lachmann, Thomas

    2013-01-01

    The present paper provides an overview of research concerning both acute and chronic effects of exposure to noise on children's cognitive performance. Experimental studies addressing the impact of acute exposure showed negative effects on speech perception and listening comprehension. These effects are more pronounced in children as compared to adults. Children with language or attention disorders and second-language learners are still more impaired than age-matched controls. Noise-induced disruption was also found for non-auditory tasks, i.e., serial recall of visually presented lists and reading. The impact of chronic exposure to noise was examined in quasi-experimental studies. Indoor noise and reverberation in classroom settings were found to be associated with poorer performance of the children in verbal tasks. Regarding chronic exposure to aircraft noise, studies consistently found that high exposure is associated with lower reading performance. Even though the reported effects are usually small in magnitude, and confounding variables were not always sufficiently controlled, policy makers responsible for noise abatement should be aware of the potential impact of environmental noise on children's development. PMID:24009598

  2. Does noise affect learning? A short review on noise effects on cognitive performance in children

    Directory of Open Access Journals (Sweden)

    Maria eKlatte

    2013-08-01

    Full Text Available The present paper provides an overview of research concerning both acute and chronic effects of exposure to noise on children´s cognitive performance. Experimental studies addressing the impact of acute exposure showed negative effects on speech perception and listening comprehension. These effects are more pronounced in children as compared to adults. Children with language or attention disorders and second-language learners are still more impaired than age-matched controls. Noise-induced disruption was also found for non-auditory tasks, i.e., serial recall of visually presented lists and reading. The impact of chronic exposure to noise was examined in quasi-experimental studies. Indoor noise and reverberation in classroom settings were found to be associated with poorer performance of the children in verbal tasks. Regarding chronic exposure to aircraft noise, studies consistently found that high exposure is associated with lower reading performance. Even though the reported effects are usually small in magnitude, and confounding variables were not always sufficiently controlled, policy makers responsible for noise abatement should be aware of the potential impact of environmental noise on children´s development.

  3. Mission management aircraft operations manual

    Science.gov (United States)

    1992-01-01

    This manual prescribes the NASA mission management aircraft program and provides policies and criteria for the safe and economical operation, maintenance, and inspection of NASA mission management aircraft. The operation of NASA mission management aircraft is based on the concept that safety has the highest priority. Operations involving unwarranted risks will not be tolerated. NASA mission management aircraft will be designated by the Associate Administrator for Management Systems and Facilities. NASA mission management aircraft are public aircraft as defined by the Federal Aviation Act of 1958. Maintenance standards, as a minimum, will meet those required for retention of Federal Aviation Administration (FAA) airworthiness certification. Federal Aviation Regulation Part 91, Subparts A and B, will apply except when requirements of this manual are more restrictive.

  4. Increased Fidelity in Prediction Methods For Landing Gear Noise

    Science.gov (United States)

    Lopes, Leonard V.; Brentner, Kenneth S.; Morris, Philip J.; Lockhard, David P.

    2006-01-01

    An aeroacoustic prediction scheme has been developed for landing gear noise. The method is designed to handle the complex landing gear geometry of current and future aircraft. The gear is represented by a collection of subassemblies and simple components that are modeled using acoustic elements. These acoustic elements are generic, but generate noise representative of the physical components on a landing gear. The method sums the noise radiation from each component of the undercarriage in isolation accounting for interference with adjacent components through an estimate of the local upstream and downstream flows and turbulence intensities. The acoustic calculations are made in the code LGMAP, which computes the sound pressure levels at various observer locations. The method can calculate the noise from the undercarriage in isolation or installed on an aircraft for both main and nose landing gear. Comparisons with wind tunnel and flight data are used to initially calibrate the method, then it may be used to predict the noise of any landing gear. In this paper, noise predictions are compared with wind tunnel data for model landing gears of various scales and levels of fidelity, as well as with flight data on fullscale undercarriages. The present agreement between the calculations and measurements suggests the method has promise for future application in the prediction of airframe noise.

  5. Sleep disturbance due to noise: Current issues and future research

    Directory of Open Access Journals (Sweden)

    Ken Hume

    2010-01-01

    Full Text Available There is growing interest in carrying out further research to understand and reduce the impact of aircraft noise on airport neighborhood in anticipation of the projected substantial increase in global aviation. Soundscapes provide new analytical methods and a broader, more comprehensive appreciation of the aural environment, which may have a useful role in understanding noise-induced sleep disturbance and annoyance. Current noise metrics like Leq do not provide a common language to report noise environment to residents, which is a key obstacle to effective noise management and acceptance. Non-auditory effects complicate the production of consistent dose-response functions for aircraft noise affecting sleep and annoyance. There are various end-points that can be chosen to assess the degree of sleep disturbance, which has detracted from the clarity of results that has been communicated to wider audiences. The World Health Organization (WHO-Europe has produced Night Noise Guidelines for Europe, which act as a clear guide for airports and planners to work towards. Methodological inadequacies and the need for simpler techniques to record sleep will be considered with the exciting potential to greatly increase cost-effective field data acquisition, which is needed for large scale epidemiological studies

  6. Human response to simulated airport noise scenarios in home-like environments

    OpenAIRE

    Lambert, Jacques; Champelovier, Patricia; BLANCHET, Régis; Lavandier, Catherine; Terroir, Jonathan; MARKI, C; GRIEFAHN, B; IEMMA, A; JANSSENS, Karl; BISPING, Rudolf

    2015-01-01

    his research is part of a FP7 project supported by the European Commission called 'Community oriented solutions to minimize aircraft noise annoyance' (COSMA). The present paper focuses on the development and the application of a methodology for the assessment of changes in airport noise exposure in home- like environments, particularly the design of sound scenarios and of experiments. Two airport noise changes are assessed and compared to a reference scenario: a halving of the number of aircr...

  7. The Role of Aircraft Motion in Airborne Gravity Data Quality

    Science.gov (United States)

    Childers, V. A.; Damiani, T.; Weil, C.; Preaux, S. A.

    2015-12-01

    Many factors contribute to the quality of airborne gravity data measured with LaCoste and Romberg-type sensors, such as the Micro-g LaCoste Turnkey Airborne Gravity System used by the National Geodetic Survey's GRAV-D (Gravity for the Redefinition of the American Vertical Datum) Project. For example, it is well documented that turbulence is a big factor in the overall noise level of the measurement. Turbulence is best controlled by avoidance; thus flights in the GRAV-D Project are only undertaken when the predicted wind speeds at flight level are ≤ 40 kts. Tail winds are known to be particularly problematic. The GRAV-D survey operates on a number of aircraft in a variety of wind conditions and geographic locations, and an obvious conclusion from our work to date is that the aircraft itself plays an enormous role in the quality of the airborne gravity measurement. We have identified a number of features of the various aircraft which can be determined to play a role: the autopilot, the size and speed of the aircraft, inherent motion characteristics of the airframe, tip tanks and other modifications to the airframe to reduce motion, to name the most important. This study evaluates the motion of a number of the GRAV-D aircraft and looks at the correlation between this motion and the noise characteristics of the gravity data. The GRAV-D Project spans 7 years and 42 surveys, so we have a significant body of data for this evaluation. Throughout the project, the sensor suite has included an inertial measurement unit (IMU), first the Applanix POSAv, and then later the Honeywell MicroIRS IMU as a part of a NovAtel SPAN GPS/IMU system. We compare the noise characteristics of the data with measures of aircraft motion (via pitch, roll, and yaw captured by the IMU) using a variety of statistical tools. It is expected that this comparison will support the conclusion that certain aircraft tend to work well with this type of gravity sensor while others tend to be problematic in

  8. 19 CFR 122.64 - Other aircraft.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Other aircraft. 122.64 Section 122.64 Customs... AIR COMMERCE REGULATIONS Clearance of Aircraft and Permission To Depart § 122.64 Other aircraft. Clearance or permission to depart shall be requested by the aircraft commander or agent for aircraft...

  9. Hearing status among aircraft maintenance personnel in a commercial airline company.

    Science.gov (United States)

    Smedje, Greta; Lunden, Maria; Gärtner, Lotta; Lundgren, Håkan; Lindgren, Torsten

    2011-01-01

    The aim was to study subjective and objective hearing loss in a population of aircraft maintenance workers and identify predictors. A total of 327 aircraft maintenance personnel answered a self-administered work environment questionnaire (response rate 76%) and underwent audiometric test. The mean values for the hearing threshold at 3, 4, and 6 kHz for the ear with the most hearing loss were compared with a Swedish population database of persons not occupationally exposed to noise. Equivalent noise exposure during a working day was measured. Relationships between subjective and objective hearing loss and possible predictors (age, years of employment, self-reported exposure to solvents, blood pressure, and psycho-social factors) were analyzed by multiple logistic regression. At younger ages (<40 years), aircraft maintenance workers had higher hearing thresholds (1-3 dB) compared to the reference group, but such a difference was not found in older employees. Relationships were found between age and objective hearing loss, and between exposure to solvents and reported subjective hearing loss. Equivalent noise exposure during working days were 70-91 dB(A) with a maximal noise level of 119 dB(A). Aircraft maintenance workers are exposed to equivalent noise levels above the Swedish occupational standard, including some very high peak exposures. Younger employees have a higher age-matched hearing threshold level compared with a reference group. Thus, there is a need for further preventive measures.

  10. Guidance Systems of Fighter Aircraft

    Directory of Open Access Journals (Sweden)

    K.N. Rajanikanth

    2005-07-01

    Full Text Available Mission performance of a fighter aircraft is crucial for survival and strike capabilities in todays' aerial warfare scenario. The guidance functions of such an aircraft play a vital role inmeeting the requirements and accomplishing the mission success. This paper presents the requirements of precision guidance for various missions of a fighter aircraft. The concept ofguidance system as a pilot-in-loop system is pivotal in understanding and designing such a system. Methodologies of designing such a system are described.

  11. 14 CFR Appendix J to Part 36 - Alternative Noise Certification Procedure for Helicopters Under Subpart H Having a Maximum...

    Science.gov (United States)

    2010-01-01

    ... Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the... Pounds J Appendix J to Part 36 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION Pt. 36, App. J Appendix...

  12. Measuring the levels of noise at the İstanbul Atatürk Airport and comparisons with model simulations.

    Science.gov (United States)

    Sari, Deniz; Ozkurt, Nesimi; Akdag, Ali; Kutukoglu, Murat; Gurarslan, Aliye

    2014-06-01

    Airport noise and its impact on the surrounding areas are major issues in the aviation industry. The İstanbul Atatürk Airport is a major global airport with passenger numbers increasing rapidly per annum. The noise levels for day, evening and night times were modeled around the İstanbul Atatürk Airport according to the European Noise Directive using the actual data records for the year 2011. The "ECAC Doc. 29-Interim" method was used for the computation of the aircraft traffic noise. In the setting the noise model for the local airport topography was taken into consideration together with the noise source data, the airport loadings, features of aircraft and actual air traffic data. Model results were compared with long-term noise measurement values for calibration. According to calibration results, classifications of the aircraft type and flight tracks were revised. For noise model validation, the daily noise measurements at four additional locations were used during the verification period. The input data was re-edited only for these periods and the model was validated. A successful model performance was obtained in several zones around the airport. The validated noise model of the İstanbul Atatürk Airport can be now utilized both for determining the noise levels in the future and for producing new strategies which are about the land use planning, operational considerations for the air traffic management and the noise abatement procedures.

  13. Noise and social deprivation in an urban environment

    Science.gov (United States)

    Shield, Bridget; Dockrell, Julie

    2001-05-01

    Noise levels have been measured inside and outside approximately 170 schools in London, England, as part of a project to investigate the effects of noise on the cognitive performance and academic attainments of children of primary school age in London. As well as providing data on individual schools the survey has provided a portrait of the noise climate across London. In addition to noise levels, the external noise sources present at each measurement location have been identified. The locations in which external schools noise levels were measured include areas where road traffic is the predominant noise source and areas near Heathrow Airport where aircraft are the major source. In addition to noise data, the following socioeconomic information has been obtained for a majority of the schools: percentages of children at each school having free school meals and the numbers for whom English is not the first language. The first of these is known to be a reliable indicator of social deprivation in an area. The relationship between noise and these socioeconomic factors has been established, which shows that, as might be expected, the higher noise levels in London are associated with the areas of greater social deprivation.

  14. Mechanics of underwater noise

    CERN Document Server

    Ross, Donald

    1976-01-01

    Mechanics of Underwater Noise elucidates the basic mechanisms by which noise is generated, transmitted by structures and radiated into the sea. Organized into 10 chapters, this book begins with a description of noise, decibels and levels, significance of spectra, and passive sonar equation. Subsequent chapters discuss sound waves in liquids; acoustic radiation fundamentals; wind-generated ocean ambient noise; vibration isolation and structural damping; and radiation by plate flexural vibrations. Other chapters address cavitation, propeller cavitation noise, radiation by fluctuating-force (dipo

  15. Comparison of Predicted and Measured Attenuation of Turbine Noise from a Static Engine Test

    Science.gov (United States)

    Chien, Eugene W.; Ruiz, Marta; Yu, Jia; Morin, Bruce L.; Cicon, Dennis; Schwieger, Paul S.; Nark, Douglas M.

    2007-01-01

    Aircraft noise has become an increasing concern for commercial airlines. Worldwide demand for quieter aircraft is increasing, making the prediction of engine noise suppression one of the most important fields of research. The Low-Pressure Turbine (LPT) can be an important noise source during the approach condition for commercial aircraft. The National Aeronautics and Space Administration (NASA), Pratt & Whitney (P&W), and Goodrich Aerostructures (Goodrich) conducted a joint program to validate a method for predicting turbine noise attenuation. The method includes noise-source estimation, acoustic treatment impedance prediction, and in-duct noise propagation analysis. Two noise propagation prediction codes, Eversman Finite Element Method (FEM) code [1] and the CDUCT-LaRC [2] code, were used in this study to compare the predicted and the measured turbine noise attenuation from a static engine test. In this paper, the test setup, test configurations and test results are detailed in Section II. A description of the input parameters, including estimated noise modal content (in terms of acoustic potential), and acoustic treatment impedance values are provided in Section III. The prediction-to-test correlation study results are illustrated and discussed in Section IV and V for the FEM and the CDUCT-LaRC codes, respectively, and a summary of the results is presented in Section VI.

  16. Noise sustained propagation: Local versus global noise

    OpenAIRE

    Locher, M.; Chatterjee, N.; Marchesoni, F.; Ditto, W. L.; Hunt, E. R.

    2000-01-01

    We expand on prior results on noise supported signal propagation in arrays of coupled bistable elements. We present and compare experimental and numerical results for kink propagation under the influence of local and global fluctuations. As demonstrated previously for local noise, an optimum range of global noise power exists for which the medium acts as a reliable transmission ``channel''. We discuss implications for propagation failure in a model of cardiac tissue and present a general theo...

  17. Noise reduction of dental drill noise

    OpenAIRE

    Rotter, KRGR; Atherton, MA; Kaymak, E; Millar, BJ

    2008-01-01

    Dental drills produce a characteristic noise that is uncomfortable for patients and is also known to be harmful to dentists under prolonged exposure. It is therefore desirable to protect the patient and dentist whilst allowing two-way communication, which will require a headphone - type system. Re-establishing good communication between the dentist and patient will be achieved through a combination of three noise cancellation technologies, namely, Passive Noise Control (PNC), Adaptive Filteri...

  18. Active noise cancellation algorithms for impulsive noise

    OpenAIRE

    Li, Peng; Yu, Xun

    2012-01-01

    Impulsive noise is an important challenge for the practical implementation of active noise control (ANC) systems. The advantages and disadvantages of popular filtered-X least mean square (FXLMS) ANC algorithm and nonlinear filtered-X least mean M-estimate (FXLMM) algorithm are discussed in this paper. A new modified FXLMM algorithm is also proposed to achieve better performance in controlling impulsive noise. Computer simulations and experiments are carried out for all three algorithms and th...

  19. Neurally based measurement and evaluation of environmental noise

    CERN Document Server

    Soeta, Yoshiharu

    2015-01-01

    This book deals with methods of measurement and evaluation of environmental noise based on an auditory neural and brain-oriented model. The model consists of the autocorrelation function (ACF) and the interaural cross-correlation function (IACF) mechanisms for signals arriving at the two ear entrances. Even when the sound pressure level of a noise is only about 35 dBA, people may feel annoyed due to the aspects of sound quality. These aspects can be formulated by the factors extracted from the ACF and IACF. Several examples of measuring environmental noise—from outdoor noise such as that of aircraft, traffic, and trains, and indoor noise such as caused by floor impact, toilets, and air-conditioning—are demonstrated. According to the noise measurement and evaluation, applications for sound design are discussed. This book provides an excellent resource for students, researchers, and practitioners in a wide range of fields, such as the automotive, railway, and electronics industries, and soundscape, architec...

  20. Chemistry in aircraft plumes

    Energy Technology Data Exchange (ETDEWEB)

    Kraabol, A.G.; Stordal, F.; Knudsen, S. [Norwegian Inst. for Air Research, Kjeller (Norway); Konopka, P. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

    1997-12-31

    An expanding plume model with chemistry has been used to study the chemical conversion of NO{sub x} to reservoir species in aircraft plumes. The heterogeneous conversion of N{sub 2}O{sub 5} to HNO{sub 3}(s) has been investigated when the emissions take place during night-time. The plume from an B747 has been simulated. During a ten-hour calculation the most important reservoir species was HNO{sub 3} for emissions at noon. The heterogeneous reactions had little impact on the chemical loss of NO{sub x} to reservoir species for emissions at night. (author) 4 refs.

  1. Hydrogen aircraft technology

    Science.gov (United States)

    Brewer, G. D.

    1991-01-01

    A comprehensive evaluation is conducted of the technology development status, economics, commercial feasibility, and infrastructural requirements of LH2-fueled aircraft, with additional consideration of hydrogen production, liquefaction, and cryostorage methods. Attention is given to the effects of LH2 fuel cryotank accommodation on the configurations of prospective commercial transports and military airlifters, SSTs, and HSTs, as well as to the use of the plentiful heatsink capacity of LH2 for innovative propulsion cycles' performance maximization. State-of-the-art materials and structural design principles for integral cryotank implementation are noted, as are airport requirements and safety and environmental considerations.

  2. Structural integrity in aircraft.

    Science.gov (United States)

    Hardrath, H. F.

    1973-01-01

    The paper reviews briefly the current design philosophies for achieving long, efficient, and reliable service in aircraft structures. The strengths and weaknesses of these design philosophies and their demonstrated records of success are discussed. The state of the art has not been developed to the point where designing can be done without major test inspection and maintenance programs. A broad program of research is proposed through which a viable computerized design scheme will be provided during the next decade. The program will organize and correlate existing knowledge on fatigue and fracture behavior, identify gaps in this knowledge, and guide specific research to upgrade design capabilities.

  3. Aeroacoustics of advanced STOVL aircraft plumes

    Science.gov (United States)

    Ahuja, K. K.; Spencer, D. A.

    1988-01-01

    This paper summarizes a basic and well-controlled experimental study involving flow visualization and noise measurements to define the acoustic and flow fields of single plumes impinging on a simulated ground plane. The flow visualization was made by strobing a laser light source at the discrete frequencies generated by the impingement of the jets and measured by a nearfield microphone. This enabled visualization of instability waves generated by the interaction between the plumes and the sound generated during impingement, and also by dynamic coupling between the two plumes. These data were acquired as a function of distance between the ground and the nozzle exit. Nearfield acoustic data were acquired simultaneously. Data for nozzle diameters of 0.265 in. and 0.4 in. are described. For selected nozzles, effects of exit boundary layer characteristics and nozzle protrusion through a simulated aircraft body are also presented.

  4. Wavelet-based acoustic recognition of aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Dress, W.B.; Kercel, S.W.

    1994-09-01

    We describe a wavelet-based technique for identifying aircraft from acoustic emissions during take-off and landing. Tests show that the sensor can be a single, inexpensive hearing-aid microphone placed close to the ground the paper describes data collection, analysis by various technique, methods of event classification, and extraction of certain physical parameters from wavelet subspace projections. The primary goal of this paper is to show that wavelet analysis can be used as a divide-and-conquer first step in signal processing, providing both simplification and noise filtering. The idea is to project the original signal onto the orthogonal wavelet subspaces, both details and approximations. Subsequent analysis, such as system identification, nonlinear systems analysis, and feature extraction, is then carried out on the various signal subspaces.

  5. Mechanisms of transmission and control of low-frequency sound in aircraft interiors

    Science.gov (United States)

    Fuller, C. R.

    1985-01-01

    A simplified analytical model is used to study the principal mechanisms at work in propeller noise source radiation, fuselage response, and the behavior of the coupled inner acoustic field, in order to control low frequency sound in aircraft interiors. Both active and passive methods of noise control are comparatively evaluated in light of the transmission mechanisms. Fuselage vibrational response is noted to be dominated by only a few lower order circumferential modes.

  6. Radial cylinder aircraft engines

    OpenAIRE

    Šimíček, Petr

    2015-01-01

    Práce je zaměřena na konstrukční řešení letadlových hvězdicových motorů. Úvod je pojednáním o historii letadlových hvězdicových motorů a jejich vývoji v historickém kontextu. Druhá část je zaměřena na konstrukci letadlových hvězdicových motorů, následně jsou uvedena některá zajímavá konstrukční řešení a porovnání s motorem jiného druhu konstrukce. The bachelor's thesis is focused on design of aircraft radial engines. Home is a treatise on the history of aircraft radial engines and their de...

  7. Aircraft landing using GPS

    Science.gov (United States)

    Lawrence, David Gary

    The advent of the Global Positioning System (GPS) is revolutionizing the field of navigation. Commercial aviation has been particularly influenced by this worldwide navigation system. From ground vehicle guidance to aircraft landing applications, GPS has the potential to impact many areas of aviation. GPS is already being used for non-precision approach guidance; current research focuses on its application to more critical regimes of flight. To this end, the following contributions were made: (1) Development of algorithms and a flexible software architecture capable of providing real-time position solutions accurate to the centimeter level with high integrity. This architecture was used to demonstrate 110 automatic landings of a Boeing 737. (2) Assessment of the navigation performance provided by two GPS-based landing systems developed at Stanford, the Integrity Beacon Landing System, and the Wide Area Augmentation System. (3) Preliminary evaluation of proposed enhancements to traditional techniques for GPS positioning, specifically, dual antenna positioning and pseudolite augmentation. (4) Introduction of a new concept for positioning using airport pseudolites. The results of this research are promising, showing that GPS-based systems can potentially meet even the stringent requirements of a Category III (zero visibility) landing system. Although technical and logistical hurdles still exist, it is likely that GPS will soon provide aircraft guidance in all phases of flight, including automatic landing, roll-out, and taxi.

  8. Aviation industry-research in aircraft finance

    OpenAIRE

    Ehrenthal, Joachim C.F.

    2010-01-01

    Aircraft values are key to aircraft financing decisions: Aircraft values act as a source of security for providers of debt capital and lessors failing to re-place aircraft, and as a source of upside potential to equity investors. Yet, aircraft values cannot be precisely and continuously monitored. This is because neither actual primary nor secondary aircraft transaction prices are disclosed. Various types of third party valuation estimates exist, but relying solely on third party appraisa...

  9. MISSILES AND AIRCRAFT (PART1

    Directory of Open Access Journals (Sweden)

    C.M. Meyer

    2012-02-01

    Full Text Available Many sources maintain that the role played by air power in the 1973 Yom Kippur War was important. Other interpretations state that control of air space over the battlefield areas, (either by aircraft or anti-aircraft defences, was vital.

  10. Solar noise storms

    CERN Document Server

    Elgaroy, E O

    2013-01-01

    Solar Noise Storms examines the properties and features of solar noise storm phenomenon. The book also presents some theories that can be used to gain a better understanding of the phenomenon. The coverage of the text includes topics that cover the features and behavior of noise storms, such as the observable features of noise storms; the relationship between noise storms and the observable features on the sun; and ordered behavior of storm bursts in the time-frequency plane. The book also covers the spectrum, polarization, and directivity of noise storms. The text will be of great use to astr

  11. Engine Validation of Noise and Emission Reduction Technology Phase I

    Science.gov (United States)

    Weir, Don (Editor)

    2008-01-01

    This final report has been prepared by Honeywell Aerospace, Phoenix, Arizona, a unit of Honeywell International, Inc., documenting work performed during the period December 2004 through August 2007 for the NASA Glenn Research Center, Cleveland, Ohio, under the Revolutionary Aero-Space Engine Research (RASER) Program, Contract No. NAS3-01136, Task Order 8, Engine Validation of Noise and Emission Reduction Technology Phase I. The NASA Task Manager was Dr. Joe Grady of the NASA Glenn Research Center. The NASA Contract Officer was Mr. Albert Spence of the NASA Glenn Research Center. This report is for a test program in which NASA funded engine validations of integrated technologies that reduce aircraft engine noise. These technologies address the reduction of engine fan and jet noise, and noise associated with propulsion/airframe integration. The results of these tests will be used by NASA to identify the engineering tradeoffs associated with the technologies that are needed to enable advanced engine systems to meet stringent goals for the reduction of noise. The objectives of this program are to (1) conduct system engineering and integration efforts to define the engine test-bed configuration; (2) develop selected noise reduction technologies to a technical maturity sufficient to enable engine testing and validation of those technologies in the FY06-07 time frame; (3) conduct engine tests designed to gain insight into the sources, mechanisms and characteristics of noise in the engines; and (4) establish baseline engine noise measurements for subsequent use in the evaluation of noise reduction.

  12. Fan Noise Source Diagnostic Test Completed and Documented

    Science.gov (United States)

    Envia, Edmane

    2003-01-01

    The specially organized session offered an international forum to disseminate the results from a year long test that was conducted in 1999 in NASA Glenn Research Center s 9- by 15-Foot Low-Speed Wind Tunnel on a 22-in. scale-model turbofan bypass stage, which was designed to be representative of current aircraft engine technology. The test was a cooperative effort involving Glenn, the NASA Langley Research Center, GE Aircraft Engines, and the Boeing Company. The principal objective of the project was to study the source mechanisms of noise in a modern high-bypass-ratio turbofan engine through detailed aerodynamic and acoustic measurements.

  13. Suppression of random noise by the separation of frequencies

    CERN Document Server

    Tibabishev, V N

    2011-01-01

    It is shown that a well-known theory of random stationary processes contain contradictions. Integral representations of correlation functions and random stationary processes are investigated further. The new method of struggle with handicaps is received on the basis of the carried out researches. Method of dealing with noise leads to a new method of identification of dynamic characteristics of control objects in a class of multidimensional linear stationary models. As an example, describe an algorithm for obtaining the differential equation-wire feed control aircraft pitch, taking into account the elastic deformation of the structure of class IL -96 aircraft.

  14. Feedback Control for Noise Reduction Program

    Science.gov (United States)

    Tucker, Jerry H.

    2002-12-01

    As part of Langley Research Center's continuing noise reduction program, an active noise control system (ANC) is being developed to suppress noise inside an aircraft cabin. This interior noise reduction system consists of the following major components: 1. Several accelerometers. 2. An input amplifier. 3. A digital signal processor (DSP) system that includes an analog to digital converter (ADC) and a digital to analog converter (DAC). 4. A high voltage power amplifier. 5. PZT actuators. 6. Power supply and distribution. The accelerometers detect interior panel vibrations. The accelerometer signals are fed to the input amplifier where they are conditioned prior to being sent to the ADC. The DSP receives the digitized signals form the ADC, processes these signals, and sends the result to the DAC. The DAC's analog output is used as input to the high voltage power amplifier. The power amplifier drives the PZT actuators to cancel noise form 50 to 1,300 Hz. The specific area of concern for this work was development of a DSP system that could be used for an actual flight demonstration. It was decided to base the system on a commercially available DSP board, the Spectrum Digital eZdsp. This was complicated by the fact that the ADC and DAC capabilities available on the eZdsp board were not sufficient to meet the system specification. Designing and fabricating a special ADC and DAC daughter card for the eZdsp circumvented this problem. The DSP system hardware has been successfully tested and is currently being integrated into the complete noise reduction system. This work has been completed in collaboration with another ASEE Fellow, Dr.William Edmonson from Hampton University and was conducted under the direction of the principle investigator, Dr. Qamar A. Shams of the Instrumentation Systems Development Branch, as part of a continuing noise reduction program.

  15. Performance and Environmental Assessment of an Advanced Aircraft with Open Rotor Propulsion

    Science.gov (United States)

    Guynn, Mark D.; Berton, Jeffrey J.; Haller, William J.; Hendricks, Eric S.; Tong, Michael T.

    2012-01-01

    Application of high speed, advanced turboprops, or "propfans," to transonic transport aircraft received significant attention during the 1970s and 1980s when fuel efficiency was the driving focus of aeronautical research. Unfortunately, after fuel prices declined sharply there was no longer sufficient motivation to continue maturing this technology. Recent volatility in fuel prices and increasing concern for aviation s environmental impact, however, have renewed interest in unducted, open rotor propulsion. Because of the renewed interest in open rotor propulsion, the lack of publicly available up-to-date studies assessing its benefits, and NASA s focus on reducing fuel consumption, a preliminary aircraft system level study on open rotor propulsion was initiated to inform decisions concerning research in this area. New analysis processes were established to assess the characteristics of open rotor aircraft. These processes were then used to assess the performance, noise, and emissions characteristics of an advanced, single-aisle aircraft using open rotor propulsion. The results of this initial study indicate open rotor engines have the potential to provide significant reductions in fuel consumption and landing-takeoff cycle NOX emissions. Noise analysis of the study configuration indicates that an open rotor aircraft in the single-aisle class would be able to meet current noise regulations with margin.

  16. Automated Design of Noise-Minimal, Safe Rotorcraft Trajectories

    Science.gov (United States)

    Morris, Robert A.; Venable, K. Brent; Lindsay, James

    2012-01-01

    NASA and the international community are investing in the development of a commercial transportation infrastructure that includes the increased use of rotorcraft, specifically helicopters and aircraft such as a 40-passenger civil tilt rotors. Rotorcraft have a number of advantages over fixed wing aircraft, primarily in not requiring direct access to the primary fixed wing runways. As such they can operate at an airport without directly interfering with major air carrier and commuter aircraft operations. However, there is significant concern over the impact of noise on the communities surrounding the transportation facilities. In this paper we propose to address the rotorcraft noise problem by exploiting powerful search techniques coming from artificial intelligence, coupled with simulation and field tests, to design trajectories that are expected to improve on the amount of ground noise generated. This paper investigates the use of simulation based on predictive physical models to facilitate the search for low-noise trajectories using a class of automated search algorithms called local search. A novel feature of this approach is the ability to incorporate constraints into the problem formulation that addresses passenger safety and comfort.

  17. Effects of noise and task loading on a communication task loading on a communication task

    Science.gov (United States)

    Orrell, Dean H., II

    Previous research had shown the effect of noise on a single communication task. This research has been criticized as not being representative of a real world situation since subjects allocated all of their attention to only one task. In the present study, the effect of adding a loading task to a standard noise-communication paradigm was investigated. Subjects performed both a communication task (Modified Rhyme Test; House et al. 1965) and a short term memory task (Sternberg, 1969) in simulated levels of aircraft noise (95, 105 and 115 dB overall sound pressure level (OASPL)). Task loading was varied with Sternberg's task by requiring subjects to memorize one, four, or six alphanumeric characters. Simulated aircraft noise was varied between levels of 95, 105 and 115 dB OASPL using a pink noise source. Results show that the addition of Sternberg's task and little effect on the intelligibility of the communication task while response time for the communication task increased.

  18. An Analytical Assessment of NASA's N(+)1 Subsonic Fixed Wing Project Noise Goal

    Science.gov (United States)

    Berton, Jeffrey J.; Envia, Edmane; Burley, Casey L.

    2010-01-01

    The Subsonic Fixed Wing Project of NASA s Fundamental Aeronautics Program has adopted a noise reduction goal for new, subsonic, single-aisle, civil aircraft expected to replace current 737 and A320 airplanes. These so-called "N+1" aircraft--designated in NASA vernacular as such since they will follow the current, in-service, "N" airplanes--are hoped to achieve certification noise goal levels of 32 cumulative EPNdB under current Stage 4 noise regulations. A notional, N+1, single-aisle, twinjet transport with ultrahigh bypass ratio turbofan engines is analyzed in this study using NASA software and methods. Several advanced noise-reduction technologies are empirically applied to the propulsion system and airframe. Certification noise levels are predicted and compared with the NASA goal.

  19. An Analytical Assessment of NASA's N+1 Subsonic Fixed Wing Project Noise Goal

    Science.gov (United States)

    Berton, Jeffrey J.; Envia, Edmane; Burley, Casey L.

    2009-01-01

    The Subsonic Fixed Wing Project of NASA's Fundamental Aeronautics Program has adopted a noise reduction goal for new, subsonic, single-aisle, civil aircraft expected to replace current 737 and A320 airplanes. These so-called 'N+1' aircraft - designated in NASA vernacular as such since they will follow the current, in-service, 'N' airplanes - are hoped to achieve certification noise goal levels of 32 cumulative EPNdB under current Stage 4 noise regulations. A notional, N+1, single-aisle, twinjet transport with ultrahigh bypass ratio turbofan engines is analyzed in this study using NASA software and methods. Several advanced noise-reduction technologies are analytically applied to the propulsion system and airframe. Certification noise levels are predicted and compared with the NASA goal.

  20. NASA propeller noise research

    Science.gov (United States)

    Greene, G. C.

    1980-01-01

    The research in propeller noise prediction, noise/performance optimization, and interior reduction is described. Selected results are presented to illustrate the status of the technology and the direction of future research.

  1. Embedded Acoustic Sensor Array for Engine Fan Noise Source Diagnostic Test: Feasibility of Noise Telemetry via Wireless Smart Sensors

    Science.gov (United States)

    Zaman, Afroz; Bauch, Matthew; Raible, Daniel

    2011-01-01

    Aircraft engines have evolved into a highly complex system to meet ever-increasing demands. The evolution of engine technologies has primarily been driven by fuel efficiency, reliability, as well as engine noise concerns. One of the sources of engine noise is pressure fluctuations that are induced on the stator vanes. These local pressure fluctuations, once produced, propagate and coalesce with the pressure waves originating elsewhere on the stator to form a spinning pressure pattern. Depending on the duct geometry, air flow, and frequency of fluctuations, these spinning pressure patterns are self-sustaining and result in noise which eventually radiate to the far-field from engine. To investigate the nature of vane pressure fluctuations and the resulting engine noise, unsteady pressure signatures from an array of embedded acoustic sensors are recorded as a part of vane noise source diagnostics. Output time signatures from these sensors are routed to a control and data processing station adding complexity to the system and cable loss to the measured signal. "Smart" wireless sensors have data processing capability at the sensor locations which further increases the potential of wireless sensors. Smart sensors can process measured data locally and transmit only the important information through wireless communication. The aim of this wireless noise telemetry task was to demonstrate a single acoustic sensor wireless link for unsteady pressure measurement, and thus, establish the feasibility of distributed smart sensors scheme for aircraft engine vane surface unsteady pressure data transmission and characterization.

  2. Coupling Reduces Noise

    OpenAIRE

    Kia, Behnam; Kia, Sarvenaz; Lindner, John. F.; Sinha, Sudeshna; Ditto, William L.

    2014-01-01

    We demonstrate how coupling nonlinear dynamical systems can reduce the effects of noise. For simplicity we investigate noisy coupled map lattices. Noise from different lattice nodes can diffuse across the lattice and lower the noise level of individual nodes. We develop a theoretical model that explains this observed noise evolution and show how the coupled dynamics can naturally function as an averaging filter. Our numerical simulations are in excellent agreement with the model predictions.

  3. Nonlinear noise cancellation

    OpenAIRE

    Strauch, Paul E

    1997-01-01

    Noise or interference is often assumed to be a random process. Conventional linear filtering, control or prediction techniques are used to cancel or reduce the noise. However, some noise processes have been shown to be nonlinear and deterministic. These nonlinear deterministic noise processes appear to be random when analysed with second order statistics. As nonlinear processes are widespread in nature it may be beneficial to exploit the coherence of the nonlinear deterministic no...

  4. Noise in electromigrated nanojunctions

    OpenAIRE

    Wheeler, P. J.; Chen, Ruoyu; Natelson, D.

    2013-01-01

    Noise measurements are a probe beyond simple electronic transport that can reveal additional information about electronic correlations and inelastic processes. Here we report noise measurements in individual electromigrated nanojunctions, examining the evolution from the many channel regime to the tunneling regime, using a radio frequency technique. While we generally observe the dependence of noise on bias expected for shot noise, in approximately 12% of junction configurations we find discr...

  5. Noise and Neuronal Heterogeneity

    OpenAIRE

    Barber, Michael J.; Ristig, Manfred L.

    2010-01-01

    We consider signal transaction in a simple neuronal model featuring intrinsic noise. The presence of noise limits the precision of neural responses and impacts the quality of neural signal transduction. We assess the signal transduction quality in relation to the level of noise, and show it to be maximized by a non-zero level of noise, analogous to the stochastic resonance effect. The quality enhancement occurs for a finite range of stimuli to a single neuron; we show how to construct network...

  6. Noise in mesoscopic physics

    OpenAIRE

    Martin, Thierry

    2005-01-01

    This is a course on noise which covers some of the scattering theory for normal metals, Hanbury Brown and Twiss analogs for noise correlations with electrons, noise correlations in superconducting/normal metal junctions. Entanglement in such NS systems is described with a criterion for violating Bell inegalities. The last section is devoted to the perturbative derivation of noise in a particular one dimensional correlated electron system (Luttinger liquid): edge states in the fractional quant...

  7. Filtering Solid Gabor Noise

    OpenAIRE

    Lagae, Ares; Drettakis, George

    2011-01-01

    Solid noise is a fundamental tool in computer graphics. Surprisingly, no existing noise function supports both high-quality anti-aliasing and continuity across sharp edges. In this paper we show that a slicing approach is required to preserve continuity across sharp edges, and we present a new noise function that supports anisotropic filtering of sliced solid noise. This is made possible by individually filtering the slices of Gabor kernels, which requires the proper treatment of phase. This ...

  8. Aircraft radar antennas

    Science.gov (United States)

    Schrank, Helmut E.

    1987-04-01

    Many changes have taken place in airborne radar antennas since their beginnings over forty years ago. A brief historical review of the advances in technology is presented, from mechanically scanned reflectors to modern multiple function phased arrays. However, emphasis is not on history but on the state-of-the-art technology and trends for future airborne radar systems. The status of rotating surveillance antennas is illustrated by the AN/APY-1 Airborne Warning and Control System (AWACS) slotted waveguide array, which achieved a significant breakthrough in sidelobe suppression. Gimballed flat plate arrays in nose radomes are typified by the AN/APG-66 (F-16) antenna. Multifunction phased arrays are presented by the Electronically Agile Radar (EAR) antenna, which has achieved significant advances in performance versatility and reliability. Trends toward active aperture, adaptive, and digital beamforming arrays are briefly discussed. Antennas for future aircraft radar systems must provide multiple functions in less aperture space, and must perform more reliably.

  9. Commercial aircraft composite technology

    CERN Document Server

    Breuer, Ulf Paul

    2016-01-01

    This book is based on lectures held at the faculty of mechanical engineering at the Technical University of Kaiserslautern. The focus is on the central theme of societies overall aircraft requirements to specific material requirements and highlights the most important advantages and challenges of carbon fiber reinforced plastics (CFRP) compared to conventional materials. As it is fundamental to decide on the right material at the right place early on the main activities and milestones of the development and certification process and the systematic of defining clear requirements are discussed. The process of material qualification - verifying material requirements is explained in detail. All state-of-the-art composite manufacturing technologies are described, including changes and complemented by examples, and their improvement potential for future applications is discussed. Tangible case studies of high lift and wing structures emphasize the specific advantages and challenges of composite technology. Finally,...

  10. Closed cycle propulsion for small unmanned aircraft

    Science.gov (United States)

    Hays, Thomas Chadwick

    This study evaluates the merit of closed cycle propulsion systems for use in unmanned systems. The complexity and added weight of closed cycle engines is offset by benefits in high altitude performance, operation in polluted air environments, multi-fuel operation, and potential for flight in low oxygen environments using generic thermal heat sources. Although most closed thermal cycles cannot match the efficiency and power density potential of internal combustion engines (ICE) and turbomachines in aircraft propulsion applications, the addition of design requirements regarding noise output, and operation at high altitude results in IC and CC engine's performance becoming much more comparable. Muffling devices increase backpressure on internal combustion engines thereby reducing power output and efficiency. Multi stage turbo supercharging for operation at high altitude can in some cases increase efficiency of ICE's, but at the result of significant additional complexity and cost that also reduces practical reliability because of the often intricate mechanisms involved. It is in these scenarios that closed cycle engines offer a comparable performance alternative that may prove to be simpler, cheaper, and more reliable than high altitude or low noise internal combustion or turbomachine propulsion systems.

  11. Characteristics of USB noise

    Science.gov (United States)

    Gibson, J. S.; Searle, N.

    1976-01-01

    An extensive series of noise measurements, for a variety of geometric and operational parameters, was made on models of upper surface blowing (USB) powered lift systems. The data obtained were analyzed and the effects and trends of parametric variation defined. The behavior and nature of USB noise and the design of USB systems with low noise characteristics is examined.

  12. Noise at the Interface

    DEFF Research Database (Denmark)

    Prior, Andrew

    2011-01-01

    The notion of noise occupies a contested territory, in which it is framed as pollution and detritus even as it makes its opposite a possibility - noise is always defined in opposition to something else, even if this ‘other’ is not quite clear. This paper explores noise in the context of ‘the...

  13. Adaptive Kalman Filter of Transfer Alignment with Un-modeled Wing Flexure of Aircraft

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The alignment accuracy of the strap-down inertial navigation system (SINS) of airborne weapon is greatly degraded by the dynamic wing flexure of the aircraft. An adaptive Kalman filter uses innovation sequences based on the maximum likelihood estimated criterion to adapt the system noise covariance matrix and the measurement noise covariance matrix on line, which is used to estimate the misalignment if the model of wing flexure of the aircraft is unknown. From a number of simulations, it is shown that the accuracy of the adaptive Kalman filter is better than the conventional Kalman filter, and the erroneous misalignment models of the wing flexure of aircraft will cause bad estimation results of Kalman filter using attitude match method.

  14. 76 FR 45011 - Control of Air Pollution From Aircraft and Aircraft Engines; Proposed Emission Standards and Test...

    Science.gov (United States)

    2011-07-27

    ... from Aircraft and Aircraft Engines; Emission Standards and Test Procedures;'' Final Rule, 62 FR 25356... From Aircraft and Aircraft Engines; Proposed Emission Standards and Test Procedures; Proposed Rule #0... and Aircraft Engines; Proposed Emission Standards and Test Procedures AGENCY: Environmental...

  15. Reconstruction of historical noise exposure data for environmental epidemiology in Switzerland within the SiRENE project

    Directory of Open Access Journals (Sweden)

    Karipidis Ioannis

    2014-07-01

    Full Text Available In 2014 the three-year interdisciplinary study SiRENE (Short and Long Term Effects of Traffic Noise Exposure was launched in Switzerland. The goal of SiRENE is to investigate acute, short- and long-term e_ects of road, railway and aircraft noise exposure on annoyance, sleep disturbances and cardio-metabolic risk.

  16. Low-noise amplifier

    OpenAIRE

    V. B. Gulkov; A. S. Makarenko

    2012-01-01

    The mixture of signal and noise processing device is considered in this article. It contains two channels: the main channel (MC) contains the mixture of signal and noise, and compensation channel (CC) that extracts just a noise from the mixture. The feature of the processing circuit is that the mixture samples are formed by short impulses at the moments of passing signal through zero. Further antiphase noise is set in the channels, adder by which the noise is removed from mixture is set on th...

  17. Compression by Noise Equalization

    OpenAIRE

    Jähne, Bernd

    2013-01-01

    For any relation of the noise variance with the gray value, a nonlinear transform h(g) can be applied so that the variance of the transformed signal h is constant. The number of bits required to represent the noise-equalized signal is in good approximation equal to the maximum signal/noise ratio (SNRmax). Thus the noise-equalized signal of any imaging sensor with a full-well capacity of less than 2^16 can be represented by only 8 bit or less with only a slight increase in the overall noise le...

  18. 36 CFR 331.14 - Aircraft.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Aircraft. 331.14 Section 331..., KENTUCKY AND INDIANA § 331.14 Aircraft. (a) The operation of aircraft on WCA lands and waters is prohibited... prohibited. (c) The provisions of this section shall not be applicable to aircraft engaged on...

  19. 48 CFR 246.408-71 - Aircraft.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Aircraft. 246.408-71... Aircraft. (a) The Federal Aviation Administration (FAA) has certain responsibilities and prerogatives in connection with some commercial aircraft and of aircraft equipment and accessories (Pub. L. 85-726 (72...

  20. 36 CFR 327.4 - Aircraft.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Aircraft. 327.4 Section 327.4... Aircraft. (a) This section pertains to all aircraft including, but not limited to, airplanes, seaplanes, helicopters, ultra-light aircraft, motorized hang gliders, hot air balloons, any non-powered flight devices...