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二、“现代”大气声学1.重力和科里奥利(Coriolis)力对声传播的影响(1)声重力波和内重力波重力场对寻常声波(包括可听声和频率较高的次声,当然更包括超声,但因后者在空气中衰减太快,不能成为大气声学研究对象)的影响完全可以忽略,但当频率低到一定程度时就必须考虑这种影响了.声波中的运动加速度与频率的平方成正比,对于寻常声波,这一加速度的数值远比重力加速度g大.但当频率的数量级约为g/c时,这两个加速度就属于同数量级的了.实际上,因重力作用,大气密度随高度增加而减小.例如,对于频率为g/c0.029Hz的声波,其波… 相似文献
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The acoustic and perceptive characteristics of discourse units, including clauses, simple sentences, compound sentences and paragraphs, were studied. The acoustic characteristics were based on the analysis of a speech corpus consisted of ten monologues. The Perceived Boundary Strength (PBS) of the monologues was labeled on a five-point scale by 25 participants. The main results are as follows: (1) There is a significant difference in the PBS of clauses (corresponding to intonational phrase), sentences (including simple sentences and compound sentences) and paragraphs. But the PBS of simple sentences and compound sentences is the same, and the pitch reset and pause are also not significantly different between these two kinds of boundaries. (2) The pitch-based cue used to distinguish clauses, sentences and paragraphs appears to be the difference between pre- and post-boundary syllables, but not simply the pitch value of either syllable alone. (3) Declination mainly occurs within intonational phrases, whereas there is no consistent global declination in sentences or in paragraphs. (4) Pauses are longer and more varied at the boundary of larger discourse units. Moreover, there is a significant positive correlation between pause duration and degree of pitch reset at clause boundaries, but not at sentence or paragraph boundaries. 相似文献
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《声学学报:英文版》2013,(4):454-457
43.05. History; 43.10. General; 43.15. Standards; 43.20. General linear acoustics; 43.25. Nonlinear acoustics; 43.28. Aeroacoustics and atmospheric sound; 43.30. Underwater sound; 43.35. Ultrasonics, quantum acoustics, and physical effects of sound; 43.38. Transdnction, acoustical devices for the gen- eration and reproduction of sound; 43.40. Structural acoustics and vibration; 43.50. Noise: its effects and control; 相似文献
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本文简述环境声学的发展过程以及在厅堂音质、环境噪声和噪声控制方面的新世纪展望。 相似文献
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声环境是环绕人们的并对其生存产生很大影响的重要条件,但以往人类只注意发展声环境的正向方面,而对于由此产生的隐伏的声危害却关注不够,从而致命声环境会给人类带来灾难性的环境压力,主人类健康,本文重点介绍突出的灾害噪声问题及其控制技术。 相似文献
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A theoretical model and signal processing of acoustic correlation measurements to estimate current velocity are discussed. The sonar space-time correlation function of volume reverberations within Fraunhofer zone is derived. The function, which is in exponential forms, is the theoretical model of acoustic correlation measurements. The characteristics of the correlation values around the maximum of the amplitude of the correlation function, where most information about current velocity is contained, are primarily analyzed. Localized Least Mean Squares (LLMS) criterion is put forward for velocity estimation. Sequential Quadratic Programming (SQP) method is adopted as the optimization method. So the systematic signal processing method of acoustic correlation techniques for current velocity measurement is established. A prototype acoustic correlation current profiler (ACCP) underwent several sea trials, the results show that theoretical model approximately coincides with experimental re- sults. Current profiles including the speed and direction from ACCP are compared with those from acoustic Doppler current profiler (ADCP). The current profiles by both instruments agree reasonably well. Also, the standard deviation of velocity measurement by ACCP is statistically calculated and it is a little larger than predicted value. 相似文献
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中国科学院声学研究所办公室 《应用声学》2004,23(5):20-20
在中国共产党成立83周年之际,中国科学院声学研究所迎来了自己的40华诞。1964年7月1日,在国家领导人的亲切关怀下,中国科学院声学研究所正式成立。经过几代声学所人的艰苦奋斗、不懈努力,声学所从无到有、从小到大,如今已经成长为专业从事声学领域研究的科技国家队,国际声学领域的知名研究机构。 相似文献
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声环境是环绕人们的并对其生存产生很大影响的重要条件,但以往人类只注意发展声环境的正向方面,而对于由此产生的隐伏的声危害却关注不够,从而致使声环境会给人类带来灾难性的环境压力,危及人类健康.本文重点介绍突出的灾害噪声问题及其控制技术. 相似文献
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《声学学报:英文版》2010,(4):428-431
43.05. History; 43.10. General; 43.15. Standards; 43.20. General linear acoustics; 43.25. Nonlinear acoustics; 43.28. Aeroacoustics and atmospheric sound; 43.30. Underwater sound; 43.35. Ultrasonics, quantum acoustics, and physical effects of sound; 43.38. Transduction, 相似文献
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由四川省声学学会、陕西省声学学会、中国声学学会超声电子学专委会和物理声学专委会联合发起,四川省声学学会承办的“2006’和谐开发中国西部声学学术会议”,以及中国声学学会超声电子学专委会和物理声学专委会的工作会议,于2006年8月14日-19日在都江堰市举行。来自北京、上海、江苏、浙江、河北、河南、湖北、山东、陕西、重庆、四川等地高等院校、科研院所及相关单位的声学科技专家、教授等共130余名代表参加了会议。中国声学学会秘书长宗健研究员、中国声学学会超声电子学专委会副主任委员吴江副所长、物理声学专委会主任委员南京大学长江学者王新龙教授出席了会议。 相似文献
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今年是中国科学院部委员马大猷教授七十五岁和从事科学与教育工作五十四周年。我们特向他表示热烈的祝贺和崇高的敬意。马大猷1915年3月1日生于北京,祖籍广东潮阳。1936年毕业于北京大学物理系,考取了清华大学留美公费生。1937年去美国,先后在洛杉矶加州大学和哈佛大学当研究生。1940年获哲学博士学位后回国,在西南联大任教,成(?)最年轻的教授。抗战胜利后曾任北京大学物理系教授,电机系系主任和工学院院长。1952年任哈尔滨工业大学教授、教务长。1956年首批当选为中国科学院技术科学部学部委员,同年调任中国科学院应用物理研究所研究员,开(?)着手组织中国的声学研究工作。 相似文献
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Acoustic vector sensor signal processing 总被引:2,自引:0,他引:2
SUN Guiqing LI Qihu ZHANG Bin 《声学学报:英文版》2006,25(1):1-15
Acoustic vector sensor simultaneously, colocately and directly measures orthogonal components of particle velocity as well as pressure at single point in acoustic field so that is possible to improve performance of traditional underwater acoustic measurement devices or detection systems and extends new ideas for solving practical underwater acoustic engineering problems. Although acoustic vector sensor history of appearing in underwater acoustic area is no long, but with huge and potential military demands, acoustic vector sensor has strong development trend in last decade, it is evolving into a one of important underwater acoustic technology. Under this background, we try to review recent progress in study on acoustic vector sensor signal processing, such as signal detection, DOA estimation, beamforming, and so on. 相似文献