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1·Posterior acoustic attenuation 82 cases.

衰减82例。

2·Meanwhile, the existence of the acoustic attenuation coefficient benefits the axial resolution.

同时，声衰减系数的存在有利于轴向分辨率的提高。

3·Two new medium parameters related to acoustic attenuation are introduced and an acoustic propagation coefficient is defined.

本文引入两个与声衰减有关的介质参量，定义了声传播系数；

4·The advantages and shortcomings of the three methods for the prediction of silencer acoustic attenuation performance are discussed.

通过算例分析和总结三种方法预测消声器声学性能的优缺点。

5·The acoustic attenuation of suspending liquid is divided three kinds as absorption attenuation and scattering attenuation and diffusion attenuation.

悬浮液的声衰减分为三种主要类型：吸收衰减、散射衰减和扩散衰减。

6·The 3-d numerical methods are used to predict the acoustic attenuation performance and flow resistance characteristics of internal combustion engine exhaust silencers.

使用三维数值计算方法预测内燃机排气消声器的声学性能和阻力特性。

7·Therefore, the present thesis will investigate in detail the calculation methods of acoustic attenuation performance of silencers and the acoustic characteristics of perforated elements.

本文针对消声器声学性能的计算方法和穿孔元件的声学特性开展系统研究。

8·Methods The color and transparency of different concentration phantoms were observed. Properties including density, acoustic speed and acoustic attenuation of PAA gel phantom were measured.

方法观察模块浓度的不同所致颜色与透明度的变化，并对PAA模块的声学特性包括密度、声速及声衰减进行测量。

9·Expresss the factors resulting in the attenuation of acoustic waves.

请陈述导致超音波衰减的各项因素。

10·After built the material's defect model in theory, combined the attenuation image and damage mechanics of acoustic, we can get the material's invalidation model.

从理论上建立材料的缺陷模型，并结合声衰减分布图与超声损伤力学原理，就能获得材料的失效模型。