Characteristics of variable‐reluctance transducers as underwater acoustic projectors

Piezoelectric Materials Used in Underwater Acoustic Transducers

Effect of porosity on the characteristics of underwater acoustic sound absorbers using theoretical models‎

Porous materials have good acoustic damping characteristics over a wide frequency range. As for sound waves, many small-scale pores in the coating materials can convert underwater-coating to rough surfaces. The main property of porous absorbents is their resistance against incident sound wave that leads to damping effect. From a physical point of view, damping occurs due to friction between flu...

A Comparison of the Underwater Acoustic Performance of Single Crystal vs. Piezoelectric Ceramic based Cymbal Projectors

The underwater acoustic performance of three same-design ‘cymbal’ based electro-acoustic projectors are compared. Two of these projectors contain PMN-PT single crystal piezoelectric as the active material while the third utilizes conventional PZT-5H piezoelectric ceramic. The units containing the single crystal material show an improvement in the acoustic source level anywhere from 3 to 15 dB o...

Underwater sound generation using carbon nanotube projectors.

The application of solid-state fabricated carbon nanotube sheets as thermoacoustic projectors is extended from air to underwater applications, thereby providing surprising results. While the acoustic generation efficiency of a liquid immersed nanotube sheet is profoundly degraded by nanotube wetting, the hydrophobicity of the nanotube sheets in water results in an air envelope about the nanotub...

Characteristics Analysis of HFM Signal over Underwater Acoustic Channels

Abstract For pulse compression characteristics and not easily affected by noise, linear frequency modulation signal are widely used in underwater acoustic communication. This paper analyzes the characteristics of hyperbolic frequency modulation signal over underwater acoustic channels. Compared with linear frequency modulation signal, hyperbolic frequency modulation has the same performance of ...