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排序方式: 共有60条查询结果,搜索用时 31 毫秒
1.
沪杭高速公路嘉善段道路声屏障的设计及降噪效果 总被引:4,自引:0,他引:4
在详细调查沪杭高速公路喜善张家浜中桥路段(试验路段)未建道路声屏障噪声情况的基础上,介绍了试验路段工程概况及道路声屏障的设计,并分析了声屏障的现场降噪效果,试验路段声屏障的声学指标达到预期目标,具有良好的环境效益。 相似文献
2.
3.
根据扁矩形消声通道二维消声理论替代一维理论导出的消声系数Φ(α),研究了障板消声结构的Φ(α)计算机程序和消声量与障板几何尺寸的关系 相似文献
4.
We need to ensure the sustainable management of advanced materials, such as purified silicon, that contribute to a low-carbon
society. Because a drastic increase in the demand for photovoltaic (PV) systems is tightening the supply of silicon for PV
cells, the sustainability of silicon feedstock needs to be explored. For this purpose, a material flow analysis of silicon
in Japan from 1996 to 2006 is presented in this paper. Our analysis finds that rapid growth in demand for polycrystalline
silicon (pc-silicon) and single crystalline silicon (sc-silicon) has changed the structure of the purified silicon supply.
The strong demand for purified silicon for solar cells is responsible for this change. While off-grade silicon obtained as
a by-product of electronic-grade silicon (EG-Si) covered the demand for solar sells before 2000, pc-silicon is currently produced
independently for solar cells via an energy-intensive process. Analysis of the resource effective-use index (REI), which indicates
how effectively purified silicon is used, shows progress in the effective use of pc- and sc-silicon. REI analysis indicates
that the effective use of pc-silicon is reaching a maximum, while the effective use of sc-silicon is advancing, with a corresponding
increase in price. To ensure a sustainable supply of silicon feedstock, this paper proposes four solutions: (1) production
of solar-grade pc-silicon by a less costly and less energy-consuming method; (2) reduction in the amount of crystalline silicon
per watt in solar cells; (3) acceleration of the development and deployment of other solar cell types; and (4) reuse and recycling
of solar cells in the future. 相似文献
5.
采用隔声窗作为典型道路的交通噪声控制措施,探索隔声性能的现场监测方法。分别选取真空玻璃窗与中空玻璃窗进行监测,两种隔声窗对交通噪声1000 Hz 和2000 Hz 两个倍频带的隔声量最大,真空玻璃隔声窗对500 Hz 倍频带及以下的噪声比中空玻璃隔声窗更有效,如果采用两种隔声窗进行组合,在全频带的隔声量达到25 dB。 相似文献
6.
Celia Arenas Carlos Leiva Luis F. Vilches Héctor Cifuentes 《Waste management (New York, N.Y.)》2013,33(11):2316-2321
The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final composite material were similar or even better than those found in porous concrete used for the same application. According to this study, the material produced presented no environmental risk. 相似文献
7.
Yuichi Moriguchi 《Journal of Material Cycles and Waste Management》2007,9(2):112-120
This article reviews recent progress in material flow analysis and its use in providing resource productivity indicators and
is based on developments in Japanese policy toward a sound material-cycle society and in international forums such as within
the Organisation for Economic Development and Cooperation, covering both institutional and methodological issues. Indicators
derived from economy-wide material flow accounts such as direct material inputs are useful to demonstrate the absolute size
of a physical economy and to reinforce the need to both reduce consumption of natural resources and limit waste generation.
Interpretation of material flows as resources and potential environmental impacts is discussed, and linkages between the size
of material flows and specific environmental impacts and damage must be further elaborated for use in environmental policy.
Lessons learned from the practical use of resource productivity indicators are also discussed. Additional indicators are needed
that can be used to evaluate the performance of microeconomic contributors. The need for an integrated approach that links
upstream resource issues and downstream waste issues through the 3Rs concept or the circular economy/society concept is attracting
increasing attention. Consequently, the accumulation of reliable scientific knowledge and data in this field in a fully international
context is essential. 相似文献
8.
Foragers of the stingless bees genus Melipona may produce intranidal sounds that are correlated with food location and quality. In this study, we provide the first detailed
analysis of pulsed sounds produced by Melipona panamica foragers while feeding on a carbohydrate food source. We trained foragers to a 2.5-M sucrose feeder under normal, ambient
temperature (23–33°C) and lower temperature (11–25°C) conditions. We recorded forager sounds under both conditions and tested
the effect of temperature of the thorax, feeder plate, and air on sound temporal characteristics. Forager energetic expenditure
and the number of pulses per visit were significantly higher in the cold condition than in the normal condition. Foragers
spent a longer time at the feeder under the cold condition than during the normal condition. Interpulse durations were significantly
shorter in the cold condition than in the normal condition and became progressively and significantly shorter at the end of
each performance. Thus, pulse production increased before departure. Foragers increased their thoracic temperatures above
ambient at all experimental air temperatures. Under chilled conditions, foragers had a significantly greater difference between
thorax temperature and ambient air temperature than under normal conditions. Foragers must achieve a minimum flight muscle
temperature before take-off, and thus forager sounds may be linked to muscle warm-up. 相似文献
9.
Laura Rodríguez-Loeches Alejandro Barro Martha Pérez Frank Coro 《Die Naturwissenschaften》2009,96(4):531-536
Both sexes of Phoenicoprocta capistrata have functional tymbals. The scanning electron microscopy revealed differences in the morphology of these organs in males
and females. Male tymbals have a well-developed striated band, constituted by 21 ± 2 regularly arranged striae whereas female
tymbals lack a striated band. This type of sexual dimorphism is rare in Arctiidae. The recording of the sound produced by
moths held by the wings revealed that while males produced trains of pulses organized in modulation cycles, females produced
clicks at low repetition rate following very irregular patterns. Statistically, there are differences between sexes in terms
of the duration of pulses, which were 355 ± 24 μs in the case of males and 289 ± 29 μs for females. The spectral characteristics
of the pulses also show sexual dimorphism. Male pulses are more tuned (Q
10 = 5.2 ± 0.5) than female pulses (Q
10 = 2.7 ± 0.5) and have a higher best frequency (42 ± 1 kHz vs. 29 ± 2 kHz). To our knowledge, this is the first report on
an arctiid moth showing sexual dimorphism in tymbal’s anatomy that leads to a best frequency dimorphism. Males produce sound
at mating attempts. The sounds recorded during mating are modulation cycles with the same spectral characteristics as those
recorded when males are held by the wings. The morphological and acoustic features of female tymbals could indicate a process
of degeneration and adaptation to conditions under which the emission of complex patterns is not necessary.
Frank Coro no longer works at Universidad de La Habana. 相似文献
10.
生产操作室隔音降噪措施及控制效果的应用研究 总被引:2,自引:0,他引:2
贾如伟 《石油化工环境保护》2002,25(1):38-42
通过对石化企业主要噪声源分布、构成情况和生产操作室隔音降噪措施琢控制效果的比较、分析,提出了生产操作室噪声控制和治理的原则、方法和设计方向。 相似文献