Some animals, such as dogs, dolphins and bats, have ears beyond human beings, so they can hear ultrasonic waves. Some people use this feature to make a silent flute that can generate ultrasonic waves to call dogs.
use
Ultrasound is widely used in military, medical and industrial fields. Its application can be divided into power ultrasound and detection ultrasound according to the power.
Applications of power ultrasound include welding, drilling, crushing, cleaning, emulsification and so on. Most of them belong to ultrasound equipment and only send unacceptable signals. At present, the exact mechanism of ultrasonic machining is still not completely clear. The military application of detection ultrasound includes radar positioning. Medical ultrasound can be observed through muscles and soft tissues, which makes this technology often used to scan many organs to assist medical diagnosis and treatment. Obstetric ultrasound is also commonly used for pregnancy examination. Doctors can use ultrasound imaging to see through the body, but because ultrasound can't penetrate the bones, although ultrasound is less harmful to the human body, it still can't completely replace X-rays. The typical ultrasonic frequency is about 2MHz to 10MHz, and the higher frequency is usually used for the vibration wave of urinary calculi. Ultrasound equipment conducted launch and reception tests.
equipment
Ultrasonic cleaning machine, which can be used for cleaning purposes, is the best cleaning method at present. It is generally believed that it uses the "hole effect" of ultrasonic wave in liquid. The cleaning principle of ultrasonic cleaning machine is to use ultrasonic vibration to clean water and generate tiny vacuum bubbles in the water. When the vacuum bubble bursts, the energy stored in the bubble is released, the release temperature is about 5000 degrees Celsius, and the pressure exceeds 10000 pound-inch, so as to take away the grease or dirt on the surface of the object. The ultrasonic frequency generated by the cleaning machine is about 20-50 kHz, which can be used to clean jewelry, lenses or other optical instruments, dental instruments, surgical instruments and industrial parts.
General ultrasound equipment is composed of ultrasonic power supply, transducer, horn and tool head except low-frequency pure mechanical ultrasonic whistle. There are two kinds of transducers: piezoelectric ceramic transducer and magnetic transducer. The theory of transducer and horn can also be considered as a specialized subject.