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US National Parks and management of park soundscapes: A review 总被引:1,自引:0,他引:1
Nicholas P. Miller 《Applied Acoustics》2008,69(2):77-92
For more than 17 years the US National Park Service has been developing the methods, processes and skills required to effectively manage the soundscapes of the National Parks. The author and his company have had the honor of providing technical acoustics related assistance throughout much of this period. This article presents his reflections on the process, its technical and political complexities, and provides what are hoped to be useful syntheses derived both from his experiences and from past and recent discussions with many of the participants. Specifically, the article describes the fundamental questions that need to be answered for management of natural soundscapes, the types of noise issues that arise in parks, the need for quantitative data, approaches to identifying, measuring and collecting those data, and a suggested approach for developing criteria designed to effectively manage sounds in natural areas. 相似文献
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Stack DW Peter N Manning RE Fristrup KM 《The Journal of the Acoustical Society of America》2011,129(3):1375-1380
Noise impacts resources and visitor experience in many protected natural areas, and visitors can be the dominant source of noise. This experimental study tested the efficacy and acceptability of signs asking visitors to be quiet at Muir Woods National Monument, California. Signs declaring a "quiet zone" (at the park's Cathedral Grove) or a "quiet day" (throughout the park) were posted on a randomized schedule that included control days (no signs). Visitor surveys were conducted to measure the cognitive and behavioral responses of visitors to the signs and test the acceptability of these management practices to visitors. Visitors were highly supportive of these management practices and reported that they consciously limited the amount of noise they produced. Sound level measurements showed substantial decreases on days when signs were posted. 相似文献
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Expo 2010 Shanghai China was a successful, splendid, and unforgettable event, leaving us with valuable experi- ences. The visitor flow pattern of the Expo is investigated in this paper. The Hurst exponent, the mean value, and the standard deviation of visitor volume indicate that the visitor flow is fractal with long-term stability and correlation as well as obvious fluctuation in a short period. Then the time series of visitor volume is converted into a complex network by using the visibility algorithm. It can be inferred from the topological properties of the visibility graph that the network is scale-free, small-world, and hierarchically constructed, confirming that the time series are fractal and a close relationship exists among the visitor volumes on different days. Furthermore, it is inevitable that will be some extreme visitor volumes in the original visitor flow, and these extreme points may appear in a group to a great extent. All these properties are closely related to the feature of the complex network. Finally, the revised linear regression is performed to forecast the next-day visitor volume based on the previous 10-day data. 相似文献
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Ware K.D. Gullickson R.L. Pierre J.M. Schneider R.F. Vitkovitsky I.M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2000,28(5):1397-1404
Nuclear weapons effects simulators are large pulsed power installations for generating intense X-ray fluxes, which are used in testing the susceptibility and hardening of military systems in the radiation environment. These simulators are expensive because of the requirement for very high power pulsed output to drive radiation loads that can provide the necessary spectral and temporal characteristics of the X-radiation suitable for testing. During the past 40 years, the Defense Threat Reduction Agency, as well as the Sandia National Laboratory, have developed pulsed power components and systems and improvements in load designs that are lowering the cost of X-ray simulators. The progress in pulsed power development encompasses elements from energy-storing capacitor banks to radiation loads and has led to the formulation of concept studies for future simulators with fewer components and with radiation loads as an integral part of the system 相似文献
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军用飞机光电平台的研发趋势与技术剖析 总被引:4,自引:0,他引:4
以高分辨力和抗电子干扰为突出特点的光电平台已成为近代军用飞机的必备装备与显著标志。本文根据近年来国外公开发表的资料,围绕21世纪服役的无人机光电载荷,有人固定翼飞机、有人旋翼飞机的光电吊舱和多传感器平 台,尤其是配置在新一代联合攻击机F35、“同温层堡垒”低空突防轰炸机B-52H、“枪骑兵”战略轰炸机B-1B、“扑食者” 无人侦察/攻击机RQ-1A/B等当今活跃在局部战争中的军用飞机上的光电装备,分析了近代军用飞机光电系统的主要优点,指出了相关光电技术与设备的瓶颈与不足,论述了机载军用光电平台的发展趋势,探讨了当前急需解决的若干技术难点,期望以此为我国军用飞机光电平台的快速发展,以及早日赶上发达国家的相应水平尽献微力. 相似文献
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A review of existing guidelines and noise laws relating to aircraft indicated that they were governed, not by the acceptability of the aircraft noise to an exposed community, but by economic considerations. To examine the impact on aircraft noise requirements of a change in emphasis, from vehicle economy to noise acceptability, existing literature was used to estimate the maximum noise exposure from aircraft that a community would probably find acceptable. The suggested limit is 90 ± 5 PNdB for twenty noise events per day. Ideally, this noise level should fall within the airport boundary or on non-residential land. 相似文献
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Fine ML Schrinel J Cameron TM 《The Journal of the Acoustical Society of America》2004,116(2):1271-1275
Physiological work on fish sound production may require exposure of the swimbladder to air, which will change its loading (radiation mass and resistance) and could affect parameters of emitted sounds. This issue was examined in Atlantic croaker Micropogonius chromis by recording sounds from the same individuals in air and water. Although sonograms appear relatively similar in both cases, pulse duration is longer because of decreased damping, and sharpness of tuning (Q factor) is higher in water. However, pulse repetition rate and dominant frequency are unaffected. With appropriate caution it is suggested that sounds recorded in air can provide a useful tool in understanding the function of various swimbladder adaptations and provide reasonable approximation of natural sounds. Further, they provide an avenue for experimentally manipulating the sonic system, which can reveal details of its function not available from intact fish underwater. 相似文献
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Overflights in national parks and preserves interfere with communication and sounds of nature. The percentage of time that an aircraft is audible, P, can be used as a noise metric. To calculate P the overflight time for a single aircraft, tau, has to be known. The method of tau calculation is based on the assumption that an aircraft is a point source and the noise propagation is governed by geometrical spreading, air absorption, and refraction. The atmosphere is characterized by the effective sound speed gradient. Analytical formulas for tau are derived for down- and crosswind flights. 相似文献
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Non-noise aspects of airport operations may affect individuals' responses to aircraft noise. Fear of crashes, other forms of pollution, and proximity to the flight path are three such non-noise aspects which have spatial patterns that are closely related to the pattern of noise contours around an airport. If these variables affect response to aircraft noise, they may therefore confound attempts to understand relationships between noise level and community response. Analyses based on data from 673 individuals around Toronto International Airport suggest that these factors do affect annoyance responses, but do not affect reported activity interference. Hence it may prove fruitful, in aggregate analyses of community response data, to control for these variables in order to better understand the noise-annoyance relationships. 相似文献
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Noise monitoring stations are in place around some military installations to provide records that assist in processing noise complaints and damage claims. However, they are known to produce false positives (by incorrectly attributing naturally occurring noise to military operations) and also fail to detect many impulse events. In this project, classifiers based on artificial neural networks were developed to improve the accuracy of military impulse noise identification. Two time-domain metrics--kurtosis and crest factor--and two custom frequency-domain metrics--spectral slope and weighted square error-were inputs to the artificial neural networks. The classification algorithm was able to achieve up to 100% accuracy on the training data and the validation data, while improving detection threshold by at least 40 dB. 相似文献
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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
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针对军用机场飞机飞行训练方式复杂多变,飞机噪声影响存在范围大、不均匀及单次事件噪声突出的特点,本文结合某军用机场实地调研测试资料,综合考察了现行评价指标对该机场飞机噪声暴露的模化效果,指出了现行指标在反映军用飞机瞬时噪声和高峰时段噪声对人的冲击影响方面的不足,提出了相应的改进措施建议,给出了高峰时段LWECPN和最大A声级LAmax两个改进指标,并分析确立了各评价指标的标准限值。最后结合调研机场的数据资料对评价指标的有效性进行了验证。论文的研究成果对军用机场飞机噪声暴露的拓展研究和通用评价指标体系的构建具有很好的参考作用。 相似文献
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Factors influencing the sound preference in urban open spaces 总被引:1,自引:0,他引:1
Lei Yu 《Applied Acoustics》2010,71(7):622-633
In this paper, based on a large scale survey in Europe and China as well as corresponding laboratory studies, the influencing factors on the sound preference evaluation, considering social, demographical, physical, behavioural and psychological facets, have been systematically examined based on statistical analyses for each of the 19 case study sites. Various sound types have been considered, including natural, human, mechanical and instrumental sounds. In terms of social/demographical factors, the results suggest that age and education level are two factors which universally influence the sound preference significantly, although the influence may vary with different types of urban open spaces and sounds. With increasing age or education level, people tend to prefer natural sounds and are more annoyed by mechanical sounds in general. It has also been found that gender, occupation and residence status generally would not influence the sound preference evaluation significantly, although gender has a rather strong influence for certain sound types such as bird sounds, especially at certain case study sites. In terms of physical factors (season, time of day), behavioural factors (frequency of coming to the site, reason for coming to the site), and psychological factors (site preference), generally speaking, their influence on the sound preference evaluation is insignificant, except for limited case study sites and certain sound types. The influence of home sound environment, in terms of sounds heard at home, on the sound preference has been found to be generally insignificant, except for certain sounds. It is noted that there are some correlations between social/demographical factors and the studied physical/behavioural/psychological factors, which should be taken into account when considering the influence of individual factors on sound preference. 相似文献
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飞机综合健康管理技术的应用对于提高飞机的安全性、维护性、降低运营成本等具有重要意义。本文通过对相关文献的整理,归纳和总结了飞机综合健康管理系统的含义,梳理了飞机综合健康管理系统发展过程,并以综合健康管理系统在B787、A380以及F-35飞机的应用为典型案例,从系统架构、功能组成等方面详细阐述了综合健康管理系统在民用和军用飞机上的最新应用,最后对飞机综合健康管理系统的发展趋势进行了探讨和展望。希望通过本文能够使读者对飞机综合健康管理技术的发展历程、最新技术水平以及未来发展方向有更加详尽的了解,对我国开展相关技术领域的研究提供有力的帮助。 相似文献
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Dhananjaya N Yegnanarayana B Bhaskararao P 《The Journal of the Acoustical Society of America》2012,131(4):3141-3152
In this paper, the acoustic-phonetic characteristics of steady apical trills--trill sounds produced by the periodic vibration of the apex of the tongue--are studied. Signal processing methods, namely, zero-frequency filtering and zero-time liftering of speech signals, are used to analyze the excitation source and the resonance characteristics of the vocal tract system, respectively. Although it is natural to expect the effect of trilling on the resonances of the vocal tract system, it is interesting to note that trilling influences the glottal source of excitation as well. The excitation characteristics derived using zero-frequency filtering of speech signals are glottal epochs, strength of impulses at the glottal epochs, and instantaneous fundamental frequency of the glottal vibration. Analysis based on zero-time liftering of speech signals is used to study the dynamic resonance characteristics of vocal tract system during the production of trill sounds. Qualitative analysis of trill sounds in different vowel contexts, and the acoustic cues that may help spotting trills in continuous speech are discussed. 相似文献
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The assessment of the impact of noise exposure on the population is a fundamental step in noise abatement. It includes the establishing of an exposure-response relationship and the setting of an impact threshold that specifies the protection level for the population and triggers eventually mitigating measures to reduce noise exposure. In Switzerland, the impact thresholds should be set so that, in the light of current scientific knowledge and experience, noise exposure below these thresholds will not seriously disturb the well-being of the population. For most current noise sources such as roads, railways and airports there already exist impact thresholds as part of the noise abatement legislation. Yet, no impact thresholds for military shooting grounds have been specified so far. Therefore a study was carried out in order to assess the impact of military noise exposure. The research included the calculation of noise exposure of eight military shooting grounds ranging from small infantry shooting ranges to expanded artillery and tank training facilities and a survey at over 1000 residents in the neighbourhood of these installations. Preliminary results suggest that although the responses of the population to military noise are rather dispersed, data should be sufficiently consistent to establish an exposure-response relationship. 相似文献