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排序方式: 共有86条查询结果,搜索用时 15 毫秒
21.
A continuous judgment by category-ratio (CJCR) scaling method was used to evaluate the instantaneous annoyance of original and modified aircraft sounds. The result from the proposed method resulted in a temporal stream of annoyance levels for the whole flyover sequence that could be further analyzed. The test subjects were continuously rating their instantaneous annoyance on a Borg CR 100 scale® during the playback of 10 flyover sequences. Using a category-ratio (CR) scale instead of a category (C) scale, mathematical operations such as calculations of average were enabled but gave also advantages in terms of higher resolution in the responses. The results showed differences in perception in the time segment where the sound had been modified. The temporal stream of annoyance was also converted into overall judgments of the sounds, these estimations showed consistency with previous results obtained using the semantic differential and paired comparison method. 相似文献
22.
This paper presents an experimental work on active control of sound transmission through a restricted opening bottom hinged window. The main goal of the work is to demonstrate the feasibility of the active technique to limit the loss of attenuation due to the aperture of windows, and its application to aircraft fly-over incident noise. The experimental window is placed in an exposed façade of a dwelling close to an airport and subject to fly-by aircraft noise. The active control is configured to cancel the pressure at the aperture using a single-input single-output feedforward adaptive system. As a result, a reduction of sound transmission is achieved with low power consumption. In global terms, an increase of almost 3 dB of transmission loss (with respect to the partially opened window insulation values) in the low frequency range (below 160 Hz and according to the National Danish Method for evaluating low frequency noise) is demonstrated, which is equivalent to a reduction of 50% in the loss of insulation caused by opening the window. 相似文献
23.
Aircraft noise contours are estimated with model calculations. Due to their impact, e.g., on land use planning, calculations need to be highly accurate, but their uncertainty usually remains unaccounted for. The objective of this study was therefore to quantify the uncertainty of calculated average equivalent continuous sound levels (LAeq) of complex scenarios such as yearly air operations, and to establish uncertainty maps. The methodology was developed for the simulation program FLULA2. In a first step, the partial uncertainties of modelling the aircraft as a sound source and of modelling sound propagation were quantified as a function of aircraft type and distance between aircraft and receiver. Then, these uncertainties were combined for individual flights to obtain the uncertainty of the single event level (LAE) at a specified receiver grid. The average LAeq of a scenario results from the combination of the LAE of many single flights, each of which has its individual uncertainties. In a last step, the uncertainties of all LAE were therefore combined to the uncertainty of the LAeq, accounting also for uncertainties of the number of movements and of prognoses. Uncertainty estimations of FLULA2 calculations for Zurich and Geneva airports revealed that the standard uncertainty of the LAeq ranges from 0.5 dB (day) to 1.0 dB (night) for past-time scenarios when using radar data as input, and from 1.0 dB (day) to 1.3 dB (night) for future scenarios, in areas where LAeq ⩾ 53 dB (day) and LAeq ⩾ 43 dB (night), respectively. Different uncertainty values may result for other models and/or airports, depending on the model sophistication, traffic input data, available sound source data, and airport peculiarities such as the specific aircraft fleet or prevailing departure and arrival procedures. The methodology, while established for FLULA2 on Zurich and Geneva airports, may be applied to other models and/or airports, but the partial uncertainties have to be specifically re-established to account for individual models and underlying sound source data. 相似文献
24.
Using the visible optics images to identify targets is an important part in the development of remote sensing technology. In this paper, a new aircraft recognition method based on the improved iterative threshold selection and the skeleton Zernike moment is presented. The method segment aircraft targets under complex background using iterative threshold selection with between-class distance and scatter, and calculate the skeleton Zernike moment for the aircraft target recognition using template matching method. The experimental results show that the new method can effectively achieve the target segmentation under complex backgrounds, and provide a satisfactory performance both in recognition rate and recognition speed. 相似文献
25.
Catherine Lavandier Benoit Barbot Jonathan Terroir Martin Schuette 《Applied Acoustics》2011,(4):169-176
This study focuses on perceived activity disturbance evaluated by participants who are subjected to the repetition noise of current aircraft and modified aircraft in regard to tonal quality. A previous study devoted to the sound quality of aircraft noise revealed that one of the most important perceptive features is the emergence of Doppler shifted tones. Six 20-min sound sequences were created combining two variables: number of aircraft (N1 with six aircraft and N2 with 10 aircraft plus one sequence without aircraft N0) and tonality (sequences with current aircraft, sequences with +5 dB-amplified tonality and sequences with −5 dB-attenuated tonality). For all sequences, the equivalent sound level and the peak level of the loudest event are constant, except for the sequence without aircraft. Sixty-three subjects, attending two different sequences in one session, rated on a category scale the level of activity disturbance due to the noise environment when carrying out memory and concentration tasks. The order of presentation was controlled as an additional variable in the variance analyses. The perceived activity disturbance is significantly influenced by the equivalent sound level. The influence of the number of aircraft flyovers is statistically significant at the 5% level. High tonal components have no effect on perceived disturbance. Memory and concentration performances, measured by number of incorrect or correct answers, are influenced only by the order of presentation, revealing the importance of the learning effect. Reaction time, which is influenced by the equivalent sound level, seems better adapted for measuring the effect of noise on task achievement. These results are discussed in regard to related research. 相似文献
26.
Abhishek Sahai Frank Wefers Sebastian Pick Eike Stumpf Michael Vorländer Torsten Kuhlen 《Applied Acoustics》2016
This paper describes a novel aircraft noise simulation technique developed at RWTH Aachen University, which makes use of aircraft noise auralization and 3D visualization to make aircraft noise both heard and seen in immersive Virtual Reality (VR) environments. This technique is intended to be used to increase the residents’ acceptance of aircraft noise by presenting noise changes in a more directly relatable form, and also aid in understanding what contributes to the residents’ subjective annoyance via psychoacoustic surveys. This paper describes the technique as well as some of its initial applications. The reasoning behind the development of such a technique is that the issue of aircraft noise experienced by residents in airport vicinities is one of subjective annoyance. Any efforts at noise abatement have been conventionally presented to residents in terms of noise level reductions in conventional metrics such as A-weighted level or equivalent sound level Leq. This conventional approach however proves insufficient in increasing aircraft noise acceptance due to two main reasons – firstly, the residents have only a rudimentary understanding of changes in decibel and secondly, the conventional metrics do not fully capture what the residents actually find annoying i.e. characteristics of aircraft noise they find least acceptable. In order to allow least resistance to air-traffic expansion, the acceptance of aircraft noise has to be increased, for which such a new approach to noise assessment is required. 相似文献
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29.
This paper describes a method for the automatic identification of acoustic events using a weighted average of sound pressure and sound intensity measured at the vicinity of airports. The classification is based on the combination of different parameters using a technique conceptually similar to the sensor fusion: the indications of different classifiers are merged using the classification uncertainty as a figure of merit. The method uses the results of a training phase for the observation of statistical distributions of sound pressure and sound intensity related parameters. The different parameters’ weights are computed analyzing the overlap of probability distributions of takeoffs and landings, so that more relevance is given to the quantities presenting a low risk of misclassification. The proposed method does not require any arbitrary assumption about the parameter effectiveness, given that the indications of multiple (potentially infinite) classifiers can be merged together with weights that minimize the chance of misclassification. The method has been validated with measurements performed at the Milan Malpensa airport (Italy). Results outlined that the proposed classification criterion correctly identifies approximately 99% of events. 相似文献
30.
The design of the control of an aircraft encountering windshear after takeoff is treated as a problem of stabilizing the climb rate about a desired value of the climb rate. The resulting controller is a feedback one utilizing only climb rate information. Its robustness vis-a-vis windshear structure and intensity is illustrated via simulations employing four different windshear models.Notations ARL
aircraft reference line
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D
drag force, lb
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g
gravitational force per unit mass=const, ft sec–2
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h
vertical coordinate of aircraft center of mass (altitude), ft
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L
lift force, lb
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m
aircraft mass=const, lb ft–1 sec2
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O
mass center of aircraft
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S
reference surface, ft2
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t
time, sec
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T
thrust force, lb
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V
aircraft speed relative to wind-based reference frame, ft sec–1
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V
e
aircraft speed relative to ground, ft sec–1
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W
x
horizontal component of wind velocity, ft sec–1
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W
h
vertical component of wind velocity, ft sec–1
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x
horizontal coordinate of aircraft center of mass, ft
-
relative angle of attack, rad
-
relative path inclination, rad
-
e
path inclination, rad
-
thrust inclination, rad
-
air density=const, lb ft2 sec2
Dot denotes time derivative. 相似文献