共查询到15条相似文献,搜索用时 86 毫秒
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通过分析询问域大小对底片乳剂颗粒产生的散斑噪声及其散斑噪声对干涉条纹识别的影响,推导出了询问域大小的选择与被测粒子位移量之间的关系,并详细讨论和分析了询问域的大小对所能探测的粒子位移量最大值的限止,以及合理选择询问域大小的依据. 相似文献
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本文利用我国的机场航空噪声评价量一计权等效连续感觉噪声级LWECPN和机场周边社区遭受机场噪声强烈干扰的人群比例PHA对机场航空噪声的暴露-反应关系进行了详细分析,得到了LWECPN~PHA关系式和关系曲线,并对LWECPN~PHA关系特点进行了分析。 相似文献
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Road traffic noise - the relationship between noise exposure and noise annoyance in Norway 总被引:1,自引:0,他引:1
Exposure-effect relationships between the level of road traffic noise at the most exposed side of a dwelling's façade and the residents' reactions to road traffic noise have been estimated. The relationships are based on five Norwegian socio-acoustic studies featuring 18 study areas from two cities and a total of near 4000 respondents. The survey questionnaires distinguish between noise annoyance experienced right outside the apartment and when indoors. Exposure-effect relationships for all degrees of annoyance are estimated simultaneously from ordinal logit models. These predict road traffic noise annoyance when right outside the apartment and when indoors, respectively, as a function of the road traffic noise level outside the most exposed façade. Separate analyses indicate that Norwegians react stronger to road traffic noise than results from a recent compilation of socio-acoustic surveys would lead one to believe. People having inferior single glazing windows report higher indoor annoyance. 相似文献
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Effects of urban morphology on the traffic noise distribution through noise mapping: A comparative study between UK and China 总被引:1,自引:0,他引:1
Due to the rapid urban development and massive population increase in many eastern cities, the difference in urban density and morphology between typical western and eastern cities is becoming significant. This consequently makes the noise distribution in the eastern cities rather different from typical low density European cities. In this research, two representative cities with different urban densities, Greater Manchester in the UK and Wuhan in China, were selected, which have low and high average urban density respectively, and also have considerable differences in building form and traffic pattern. In the mean time, these two cities have similar urban scale and traffic amount. In each city, based on the urban morphological analyses considering urban land-use, building and road density, and noise source distribution, a number of typical urban areas, 500 * 500 m2 each, were sampled. A noise-mapping software package was then used to generate generic noise maps, based on existing digital vector maps for terrain and building, and traffic data obtained by on-site measurements. The comparison results show that the average and minimum noise level in Greater Manchester samples is generally higher than that in Wuhan samples, while the maximum noise level in Wuhan samples is mostly higher. By developing a Matlab program, correlations have been analysed between noise distributions and the urban characteristics relating to urban density, such as the road and building coverage ratio. Overall, comparisons between these two typical cities have shown significant effects of urban morphology on the traffic noise distribution. 相似文献
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This research has developed a systematic aircraft noise charge scheme, based on noise social costs, with a view to its application in Taiwan. The paper starts with a brief review of current structures and applications of noise charges, a market-based measure, in mitigating aircraft noise worldwide. The evaluation of aircraft noise social cost is an attempt at putting noise nuisance into monetary terms. The total and average noise social cost per flight at one airport is clearly different from another, depending mainly on the size of the noise contour and the number of residents affected. This research estimates the average noise social costs at various airports, using nine Taiwanese airports as case studies. Depending on the marginal impact of a flight and the mixture of aircraft types at each airport, the noise social cost per landing and take-off is then estimated for different aircraft types. The results of this study can inform airport, airline and local administration policies for taking environmental concerns into account when setting up noise charges, revising noise insulation schemes, and developing strategies for airport expansion and airline operations. 相似文献
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Utilizing noise mapping for environmental impact assessment in a downtown redevelopment area of Seoul, Korea 总被引:2,自引:0,他引:2
In environmental impact assessment, noise impact assessment usually consists of three stages: surveying the existing noise levels, predicting noise levels induced by future construction works and predicting noise levels after the completion of a project. The distance-attenuation relation of a point source, which has been used in Korea to predict the noise level due to its simplicity, does not consider complex acoustic phenomena like multi-reflections, diffractions and absorptions that arise due to the complex topographic configurations of surrounding buildings and terrains. To consider such physical and acoustical complexities, a noise mapping tool is adopted to produce a series of three noise maps: for the present environment, for the planned construction works and for the future. For meaningful noise mapping, both acoustically- and topographically-good information is essential. Standard sound power levels and directivities of various construction equipments are required. Exact scheduling of construction processes and equipment locations must be provided. When the legal limit is exceeded, mitigation measures are applied to satisfy these limits and a subsequent noise map is constructed to verify the effect of these measures. Foreign prediction models are adopted for the situations in Korea if a certain validation condition is satisfied. 相似文献
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Guijun Hu Jiawei Shi Yingxue Shi Xiaosong Yang Jing Li 《Optics & Laser Technology》2003,35(6):481-483
The low-frequency noise is a sensitive non-destructive indicator of semiconductor devices reliability. In this paper, the noises in InGaAsP/InGaAs/GaAlAs double quantum well semiconductor laser diodes (LDs) are measured, and the correlation between the noise and device reliability is studied. The insults indicate that the noise level in the LDs operating in low bias current is very important for estimating device reliability. So when noise is used as reliability indicator, the noise levels in LDs operating in both low and higher bias current should be considered, which improves the validity of reliability estimation. 相似文献
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Integrated noise model (INM) is the most internationally used software to calculate noise levels near airports. Take off, landing or pass by operations can be modeled by INM, but it does not consider aircrafts taxiing, which, in some cases, can be important to accurately evaluate and reduce airports’ noise assessment.Aircraft taxiing noise emission can be predicted using other prediction tools based on standards that describe sound attenuation during propagation outdoors. But these tools require data inputs that are not known: directivity and sound power levels emitted by aircraft during taxiing.This paper describes methods used to calculate directivity indexes and sound power levels, based on field measurements made in Madrid-Barajas Airport (Spain). Obtained results can be used as inputs for general purpose outdoor sound prediction software, which will be able to evaluate noise at airports vicinity as industrial noise.Directivity and sound power levels have been estimated in octave and third octave band terms, for several aircraft families. 相似文献
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Scenario analysis and noise action planning: Modelling the impact of mitigation measures on population exposure 总被引:1,自引:0,他引:1
This paper reports on strategic noise mapping research conducted in Dublin, Ireland. Noise maps are constructed for the day–evening–night-time and night-time periods and levels of population exposure are estimated for the same periods. In methodological terms, the research uses the UK’s calculation of road traffic noise (CRTN) method for calculating noise levels in the study area. This method has been adopted as the interim calculation method by the Irish authorities responsible for meeting the obligations set out in the EU Environmental Noise Directive (END). The research also investigates the usefulness of three noise mitigation measures for ‘acoustical planning’ purposes: traffic reductions, speed reductions and erection of acoustical barriers. The results indicate that levels of population exposure during night-time are extremely high relative to guideline limits set down by the World Health Organisation. In addition, the results highlight the significant role that certain noise mitigation measures can play in good ‘acoustical planning’. 相似文献
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S. Anyogita 《Applied Acoustics》2004,65(2):195-201
Measurements of noise and its spectral characteristics were made inside various types of transport running on Compressed Natural Gas (CNG) fuel in Delhi. Noise indices L10, L50, L90 and Leq were estimated from the measured noise levels for vehicles in neutral gear, slow speed (speed ?20 km/h) and under free flow (speed ?30 km/h) conditions. It is found that background levels, when averaged over all speeds, are maximum in Rural Transport Vehicles (RTV) followed by Buses, Auto-rickshaws and Taxis. With increase in the speed, noise levels are appreciably enhanced except in the case of auto-rickshaws where the increase is moderate. The spectral distributions of noise inside vehicles obtained at 1-octave band frequencies, show a rather similar nature. The study reveals significantly lower noise levels inside CNG driven public modes of transport compared to those found in an earlier survey inside diesel and petrol driven vehicles. 相似文献