目的研究凹球面超声换能器的声焦域在高声强和媒质有较大衰减情况下，其形状和几何位置的变化。

Objective the variations of the site and shape of focal region for a concave spherical ultrasound transducer in the case of high sound intensity and stronger attenuation were studied.

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地下边界根据电磁波在导电媒质中快速衰减的特性设定，将改进的完全匹配层用于空中边界。

The subsurface boundary condition is determined by behavior that electromagnetic waves attenuated in the earth, and the modified perfect match layer is for air boundary.

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前言：目的：研究声衰减系数、声速、温度等媒质参数对声聚焦的影响。

Objective: Study the influence of parameters such as attenuation coefficient, velocity of sound, and temperature of medium on focusing sound field.

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