What are the applications of ultrasound, and what is the future of its development, and references, I am used to write a paper, I hope you can be more detailed!

Ultrasonic applications are very wide. But at present the more mature are:

1: ultrasonic underwater ranging military and civilian use of technology are very mature.

2: ultrasonic flaw detection, the current engineering applications are widely used, metal structures, steel structures and concrete areas.

3: ultrasonic cleaning, descaling, crushing (medical in vitro lithotripsy, etc.), atomization and so on.