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海洋开发和反潜战的需求是推动声纳技术开发的巨大动力,水声物理、水声信号处理及相关学科的发展又促使声纳设计日趋完善,本文介绍声纳技术在进入21世纪时所面临的机遇和挑战;水声信号处理领域近期研究的热点问题以及声纳系统设计中的技术创新课题。 相似文献
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声波是目前唯一能在海洋中远距离传播的波动形式,发展水声技术具有极其重要的应用背景。作为一门交叉学科,近十年来水声技术的发展是与水声物理、信号处理以及海洋环境的紧密结合是分不开的,本文利用最近的研究成果来说明这一趋势。 相似文献
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以一个水声被动测量系统的工程项目为平台,介绍与其配套的水下多路水声测量系统的构成、主要电路环节和工作原理。 相似文献
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本文研究并设计实现了一种用于浅海水声信道多速率通信的无线/水声通信(racom)浮标,介绍了其水声通信和无线通信技术方案和工程设计与实现。本文设计的浮标综合了水声通信、DSP信号处理和无线电通信等技术,也可以用作水声通信/传感网络中的无线/水声通信(racom)网关节点。海上试验验证了本浮标总体设计方案的可行性。海上试验中,浮标无线通信距离达到15.2 km,误码率不大于10 6;除2 kbps速率外,浮标各种速率的水声通信数据传输误码率都小于1%,最大通信作用距离达到9.6 km;同时,试验也验证了浮标与水下运动平台之间的通信功能。 相似文献
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本简述了近年来水声信号处理领域中若干专题的研究进展。包括水声通信,合成孔径声纳,水声数据融合,声层析以及水下GPS系统等。 相似文献
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声场的空间相关特性是声场的重要特征,对水下探测、水声通讯等各种设备在实际海洋环境中应用的参数选择具有重要意义,是水声工程技术研究的重要基础之一。相比于水中声源激发声场的相关特性研究,空气中声源的相关研究很少。本文推导了空气中声源激发水下声场的水平纵向相关的简正波表达式,并通过数值仿真分析,比较了声源分别位于空气中和水中时水下声场的水平纵向相关特性。对南海海域进行的一次悬挂汽笛空气声源、海底水平阵接收信号海上实验获得的数据进行分析,结果表明:空气中声源位于不同距离时,其发射的声信号激发水下声场的水平纵向相关均存在明显的起伏结构,基于本文提出的空气中声源激发水下声场的水平纵向相关系数的简正波表达式能够较好地解释该现象. 相似文献
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The paper studies the patterns manifesting themselves in the formation and propagation of caustic and weakly diverging beams using the geometric acoustic approximation and mode theory applied to the simplest model of an underwater sound channel open to the bottom in the form of the bilinear dependence of the square of the refractive index on depth. It is established that when a vertical array emitting a tonal sound signal is located at a certain critical depth, the multimode caustic beam which forms near the reference ray horizontally departing from its center and which predominates in intensity is simultaneously the most weakly diverging beam. It is shown that the reference ray of such a weakly diverging caustic beam corresponds to the smoothest minimum for the dependence of the length of the ray cycle on their angle of departure from the center of the array and to the depth level of revolution at the critical depth characteristic of the given oceanic waveguide. 相似文献
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基于水声超材料吸声机理和多层平行介质平面波理论,建立局域共振型水声超材料结构,通过COMSOL进行建模计算,研究该结构的吸声性能机理,此外为了验证钢背衬的隔声性能,在该水声超材料结构基础上添加一层0.005m厚的钢背衬进行仿真对比。研究结果表明,在频段为200Hz-4000Hz时,水声超材料声学性能较好,吸声性能整体较优,且添加钢背衬的水声超材料隔声性能较优,甚至在某频率点达到15dB的隔声差值;此外通过位移场图进一步揭示水声超材料的吸声机理,发现水声超材料结构的位移场和钢背衬都对吸声性能会产生影响,钢背衬通过影响共振吸收来影响吸声性能,而位移场则通过位移幅度大小影响吸声性能。 相似文献
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We consider the patterns manifested during the formation of the spatial intensity distribution of an acoustic field excited by a vertical array in a deep-water oceanic waveguide with an underwater sound channel open to the surface and an acoustically transparent bottom. The study focuses on the dependence of the spatial divergence of multimode beams on the angle of compensation of an array emitting a tone signal. It is established that if the size of the array aperture significantly exceeds the optimal size, then at a certain angle of compensation appreciably differing from zero, a multimode beam forms with minimal diffraction divergence even in the absence of bending points and smooth extrema of the dependence of the length of the ray cycle on the ray parameter. 相似文献
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In this paper, we present a novel approach based on pattern recognition to treat the underwater localization. The goal is to achieve underwater localization by the pattern matching algorithm. It should be noted that the reflected signals in underwater environments do not affect our location estimation. Therefore, the underwater localization in this study is straightforward and efficient by using the pattern matching algorithm. We exploit the maximum likelihood (ML) to perform our study. Initially, the underwater signals are collected by the sound receiver at some sampling locations. These signals are suitably processed by the ML models and are stored in database. The test location in real-time is estimated through the database. Experimental results show that good accuracy of positioning can be obtained by proposed schemes. The proposed localization schemes can be applied to many other applications in underwater environments. 相似文献
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Wen J Zhao H Lv L Yuan B Wang G Wen X 《The Journal of the Acoustical Society of America》2011,130(3):1201-1208
Recently, by introducing locally resonant scatterers with spherical shape proposed in phononic crystals into design of underwater sound absorption materials, the low-frequency underwater sound absorption phenomenon induced by the localized resonances is observed. To reveal this absorption mechanism, the effect of the locally resonant mode on underwater sound absorption should be studied. In this paper, the finite element method, which is testified efficiently by comparing the calculation results with those of the layer multiple scattering method, is introduced to investigate the dynamic modes and the corresponding sound absorption of localized resonance. The relationship between the resonance modes described with the displacement contours of one unit cell and the corresponding absorption spectra is discussed in detail, which shows that the localized resonance leads to the absorption peak, and the mode conversion from longitudinal to transverse waves at the second absorption peak is more efficient than that at the first one. Finally, to show the modeling capability of FEM and investigate shape effects of locally resonant scatterers on underwater sound absorption, the absorption properties of viscoelastic materials containing locally resonant scatterers with ellipsoidal shape are discussed. 相似文献
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激光声遥感探测水下声信号技术,是比以往任何一种水声探测技术都先进的技术,但探测系统的灵敏度一直未曾分析。得出了在直接光强检测方式下表面微波的最小可探测幅度值,并且分析了最小可探测幅度值分别和探测高度、接收孔径的关系。在直接光强检测方式下,针对水下声场形成的表面微扰现象,通过建立探测系统的一维物理模型进行理论推算。直接光强检测方式下表面微波的最小可探测幅度值为0.424 4 mm,当表面微波幅度超过该值时,探测系统灵敏度完全满足对水下声场的实时监测要求。 相似文献
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Sound propagation in inhomogeneous waveguides with sound-speed profiles using the multimodal admittance method 下载免费PDF全文
《中国物理 B》2020,(1)
The multimodal admittance method and its improvement are presented to deal with various aspects in underwater acoustics, mostly for the sound propagation in inhomogeneous waveguides with sound-speed profiles, arbitrary-shaped liquid-like scatterers, and range-dependent environments. In all cases, the propagation problem governed by the Helmholtz equation is transformed into initial value problems of two coupled first-order evolution equations with respect to the modal components of field quantities(sound pressure and its derivative), by projecting the Helmholtz equation on a constructed orthogonal and complete local basis. The admittance matrix, which is the modal representation of Direchlet-to-Neumann operator, is introduced to compute the first-order evolution equations with no numerical instability caused by evanescent modes. The fourth-order Magnus scheme is used for the numerical integration of differential equations in the numerical implementation. The numerical experiments of sound field in underwater inhomogeneous waveguides generated by point sources are performed. Besides, the numerical results computed by simulation software COMSOL Multiphysics are given to validate the correction of the multimodal admittance method. It is shown that the multimodal admittance method is an efficient and stable numerical method to solve the wave propagation problem in inhomogeneous underwater waveguides with sound-speed profiles, liquid-like scatterers, and range-dependent environments. The extension of the method to more complicated waveguides such as horizontally stratified waveguides is available. 相似文献
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基于修正的Rayleigh气泡脉动方程对水下等离子体声源放电产生的 强声冲击波的传播过程进行了分析; 利用Euler方程作为控制方程组, 建立了水下等离子体声源的聚束声场模型, 通过仿真计算获得的传播云图对冲击波负压的形成机理进行了直观的理论分析. 结果表明: 经过聚能反射罩反射汇聚得到的聚束波在反射稀疏波和水的惯性作用下, 聚束波周围水域产生了拉伸, 形成负压区, 如果拉伸力大于水的抗拉上限, 就会使得水中形成不连续现象, 即出现空化气泡; 此外聚能罩边缘处产生的衍射波进一步加剧了负压的产生, 边缘衍射波最终与拉伸波叠加, 使冲击波负压达到最大值; 通过对比仿真波形和实验波形, 从而验证和进一步揭示了冲击波负压的形成原因. 研究结果对认识水下冲击波的传播规律和进一步改进等离子体声源的设计具有指导意义.
关键词:
等离子体声源
冲击波负压
聚束声场模型
气泡 相似文献