【作者】 任群言；

【导师】 朴胜春； Jean-Pierre Hermand；

【作者基本信息】 哈尔滨工程大学 ， 水声工程， 2013， 博士

【摘要】 浅海环境下，海底地声参数对水声信号传播有着重要的影响，也是水下声纳应用的重要前提，因而海底地声参数获取研究一直是水声中的热点问题。由于主动信号的局限性、如对海洋生态环境的破坏性及特殊情况下的隐身要求使得利用被动声源进行地声参数反演越来越受到重视。在近海海域，由于舰船（渔船和运输船）大量存在，它们航行时候产生的噪声是水声应用的重要声源，也是我们的工作重点。在此背景下，本论文对利用舰船噪声进行海底地声参数获取作了研究，其主要内容包括以下几个部分：（1）论文第一部分回顾了地声参数反演研究的历史，对地声参数反演技术的发展历程及主要反演方法进行了总结概括，并对它们的特点进行了简单分析。该部分内容也对海洋噪声特性研究及利用噪声进行水声应用研究做了简单回顾。海洋噪声的多样性、复杂性及不确定性，使得很难直接应用于传统主动声学方法中，这就需要研发新设备或者新的处理方法。矢量水听器由于可同点同时测量水声中的声压和矢量场信息，因此现在被越来越多的研究学者所应用，关于矢量水听器及其矢量场方面的研究和应用在该部分有简要概述。（2）论文的第二部分主要介绍了线性声学理论及一些受声源影响较小比较适用于被动声学的物理观察变量。理论推导和数值仿真研究发现舰船宽带噪声的矢量场也存在有规则的干涉结构，而且矢量场的干涉结构和声压场干涉结构有所不同、并且该差异由环境条件决定的、因而可以反过来应用到环境参数反演中。通过联合声压场和矢量场处理，我们可以提取更能体现声场干涉特性的声能流分量，这对那些基于声场干涉特性的应用无疑是有帮助的。同样地、也是通过联合声压场和矢量场处理得到了和声源谱级无关但是对地声参数极高敏感的波导特征阻抗比，非常适合作为被动声学中的观察变量。该部分也给出了不同宽带声矢量场时域信号预测的数值研究及其相互比较进行了验证。（3）论文的第三部分介绍了利用声场干涉法通过分析舰船噪声干涉结构进行沉积层地声参数反演。通常来说，舰船噪声的低频干涉条纹大致结构受声源谱特性影响不大，但干涉条纹的位置会随环境缓慢变化。理论分析发现低频干涉条纹位置随环境参数变化的规律是近乎线性的，并通过数值仿真给出了典型浅海模型下沉积层参数（声速和厚度）和低频干涉条纹变化规律。基于该变化规律，我们提出了一个基于推导出的变化规律的声场干涉法进行沉积层参数估计，并处理了地中海上实验采集的舰船噪声数据，处理结果和之前同一海域利用主动声源测量的结果符合的很好。理论和实验处理数据也证实该方法对声源深度和距离的都具有一定的稳健性，非常适合于未知被动表面声源进行地声参数反演。（4）论文的第四部分介绍了基于全局优化算法和波导特征阻抗比反演海底参数的研究。由于波导特征阻抗比的声源谱级无关性及对环境参数的高敏感性，使得其非常适合应用于被动环境测量。该部分讨论了波导特征阻抗比对环境参数的敏感性分析，并处理了大连海域采集的渔船噪声矢量声场数据，分别使用声压场、矢量场和波导特征阻抗比进行了地声参数反演，结果显示，利用波导特征阻抗比的反演结果比单独使用声压场或者矢量场更符合实际实验海域的地声特性。更多还原

【Abstract】 The ocean bottom geoacoustic parameters have significant effects on the soundpropagation and sonar performance predictions in shallow waters; therefore geoacousticinversion has been a very hot topic in underwater acoustics. Due to the limitations of activesources, e.g., environmental protection and security reason in particular situations, the usingsound sources already exist in the ocean for geoacoustic inversion is drawing more andmore attentions. In shallow waters, there exist plenty of ship activites (fishing and shipmen),whose noise is a good resource for passive acoustic applications. Based on theseconsiderations, this thesis studies the using ship noise for ocean bottom geoacousticinversion, which includes the following main aspects:(1) The first part reviews the past researches on geoacoustic inversion, which brieflyintroduces the geoacoustic history and the main advantages and disadvantages of traditionalgeoacoustic inversion techniques. This section emphasizes these researches on the oceansound noise characteristics and these applications based on the noise sources. Due to theuncertainty and complicity of oceanic noise, it is hard to directly apply active acoustictechniques in passive sources, which needs newly developed equipments or new methods.Since a vector sensor can simultaneously measure the pressure and vector field of the soundfield at the same point, the using vector sensor in acoustic applications are more and morepopular in underwater acoustics. The vector sensor research history and applications arealso reviewed in this section.(2) The second part introduces the linear acoustic propagation theory in shallow watersand theoretical basises for our applications. The broadband vector field of a ship source ofopportunity is found also exhibits interference structure but has different structure with thatof pressure field. Their structure differences are determined by environmental properties andcan therefore be used for environmental inverse problems. Through investigation, thecombination of pressure filed and vector field can achieve physical observables that betterinterpret the waveguide interference characteristics, which is favorable for thoseapplications exploiting the waveguide interference characteristics. The waveguidecharacteristics impedance is obtained also through the combination of pressure field andvector field, which is source spectal level independent but very sensitive to geoacousticparameters. These features make it favourable to be observed for passive inversion purpose.In this section, some numerical researchs on the time-domain broadband vector signal predictions are also given.(3) The third section discusses the using interference structure of a broadband shipnoise for sediment geoacoustic inversion. The low-frequency striations structure of a shipnoise of opportunity is found weakly affected by the source spectrum shape, but theirlocations are slightly changed according to environmental perturbations (here refer tosediment sound speed and thickness). Their relationship is theoretically analysed andnumerical interpreted under a typical shallow water environment. Based on the relationship,an interferometer technique is proposed to characterize the sediment property variations in asofted-sediment shallow water environment. The ship noise data collected in MediterraneanSea is processed and the results agree well with those of active measurements in the sameexperiment site. The robustness of the method to uncertainties of source depth and range isalso discussed.(4) The fourth part is about the research on using the waveguide characteristicimpedance measured by a vector sensor due a ship noise for ocean bottom geoacousticinversion. A global search optimize algorithm based inversion scheme is used to estimatethe geoacoustic parameters and their uncertainties. In this section, we process the ship noisedata measured at Dalian sea, the inversion scheme is respectively applied to the pressuredata, vector data and the waveguide characteristic impedance due to a passing-by ship. Theinversion results of the waveguide characteristic impedance show better agreement withprior information of the geoacoustic properties of this sea area, demonstrating the accuracyof using waveguide impedance for passive geoacoustic inversion.更多还原