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文中讨论了无切变弹性、介质参数为线性函数的非均匀层中当了H/λ?1时的点源波场(H为层厚,λ为波长),对三种非全反射的界面所形成的反波导传播,进行了理论探讨。在使用温-克-布(W.K.B.)近似下,对场的简正波的频散方程,得到了射线解释。在引用数值反射系数边界条件下,给出以反射系数表征的波动影区的场强公式:为I~1/r e(r/2(a/(2H))1/2·ln|V|),r为距源的水平距离,H为层厚,α为波速梯度。V为层下界面的平面波反射系数。 相似文献
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According to the method of angular power spectrum for averaged sound field in shallow water,the transformation relation between arbitrary angle dependence of hottom scattering and the rangedependence of long-range reverberation in shallow water homogeneous layer is established.Ascompared with the conventional model of boundary reverberation at short range in deep sea,a multipath correction factor is added.By using the transformation relation,the bottombackscattering strength for the frequency band of 0.8—4.0kHz and grazing angle range of 2—10°has been derived from shallow-water reverberation data at five locations in the Yellow Sea,theBobai Sea and the East China Sea.It is shown that the bottom scattering constant(μ)and theangle index(2n)for high speed sediment of the continental shelf depend not only on sea area andfrqucncy,but also on angle range. 相似文献
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渐变吸收层反射率的近似式 总被引:3,自引:0,他引:3
本文讨论了渐变吸收层的反射问题,并给出W.K.B.近似下反射率的表式.作为应用的例子,文中计算了圆锥形尖劈的反射率.与实验结果进行比较,基本符合.由于所得到的近似公式十分简单,便于分析计算.并可为尖劈设计中的参数选择提供一定的依据. 相似文献
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It has been shown that for"high speed"sediment the effects of layered structure of the sedimentare not significant for a certain range of frequency at small grazing angle,and the reflection behaviorapproaches to the Rayleigh reflection specifled by the surficial sediment pararneters(p,c,a).In thatcase the frequency dependence of reflection loss is mainly due to scattering of the surface roughness.If the scattering loss is considered by using the Bass perturbation theory,the reflection loss at smallgrazing angle can be written as: -In|νφ={Q_0(p,c,a)+Q_1(f,σ)}φwhere Q_0 is the term due to Rayleigh loss independent of frequency,Q_1 is the term due to scatteringloss depending on frequency f and the spectral density of surface roughness.Some experiments,from which parameter Q can be extracted,are analysed.It is found,that in given frequency range(0.5—3.0kHz)the magnitude and the tendency of variation of the parameter Q extracted fromdiffernt experiments are distributed in the permissible region predicted 相似文献
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中国科学院水声物理考察团一行六人在团长韦宝锷教授率领下(湖北物理所4人,声学所2人)于1979年6月1日至6月21日赴日考察水声物理及水下声全息的研究概况。考察团在日本受到日中科技交流协会及日本科学家的热情友好的接待,在日本参观考察了有关的大学、研究所,工厂企业的研究机构共15个民用水声研究单位。在考察期间与日本海洋音响研 相似文献
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浅海远程混响与海底散射强度 总被引:1,自引:0,他引:1
利用浅海平均声场角度谱分析法,在海底散射的任意角度关系和浅海均匀层远程混响的距离关系之间建立了变换关系。与国外沿用的深海近程界面混响理论相比,多了多途传播修正因子K(公式18)。利用该变换关系式,由黄海、渤海、东海等5个海区的浅海远程混响资料,推得频率为0.8—4kHz,掠射角为2—10°的低频、小掠角海底散射强度。所得结果与国外深海直接测量的大掠角数据衔接较好。结果同时表明,大陆架高声速海底散射常数(μ)和角度指数(2n)不仅与海区、频率有关,而且与角度范围有关。在掠角很小时,海底散射强度随掠角减小比中等掠角时衰减更快。 相似文献
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本文将准平面波在随机信道中受到的横向随机扰动考虑为平稳高斯过程,分析计算了均匀浅海信道中由温度微结构及随机起伏界面所引起的信号场横向相干性减弱的情况.在实际感兴趣的“3/2次方”场区,给出大横向距离的相关系数为其中k_0为波数,μ~2,a为水团参数,σ_H~2为随机界面的起伏方差,Ω为海底反射损失随掠角变化的平均斜率,H_0为平均海深,r为传播距离. 相似文献