【摘要】 <正>近年来,声学方法被愈来愈多地用于海底的探测。因此,如何从海底的回声波形中提取有关海底的信息是海洋声遥测中的一个重要问题。本文介绍我们近几年对手榴弹爆炸声海底反射波形分析的部分结果。由于某些浅地层剖面仪的声源波形已接近手榴弹的爆炸波形,因此,爆炸声的分析结果向实用的过渡是不困难的。更多还原

【Abstract】 Sound wave has now become an important means in sea floor telemetering, therefore, how to get more information about marine sediments from reflected acoustic signals is an interesting subject.When the low velocity sea floor involves a thin layer with higher porosity on its top, the explosive impulse reflected from the sea floor at small grazing angles is characterized by a short depression in front of a positive impulse. The critical grazing angle θk at which the depression begins to appear depends on the density and velocity in the soft and thin layer.The density and velocity are both related with the porosity,thus the poroisty(and,in turn, the velocity and density) can be estimated with the measured θk. Finally, the thickness of the thin layer can be estimated with the duration of the depression.This report gives several sets of recorded explosive wave forms, the measured porosity profiles and the estimated values of the porosity and thickness of the soft and thin layer. Coincidence between the measured and estimated values is very good. For example, differences between the measured and estimated porosity values are within± 1 % at three experimental stations.更多还原