“ultrasonics”的概念、定义、翻译、参考文献-科学参考

ultrasonics

Physics

The study and use of pressure waves that have a frequency in excess of 20 000 Hz and are therefore inaudible to the human ear. Ultrasonic generators make use of the piezoelectric effect, ferroelectric materials, or magnetostriction to act as transducers in converting electrical energy into mechanical energy. Ultrasonics are used in medical diagnosis, particularly in conditions such as pregnancy, in which X-rays could have a harmful effect. Ultrasonic techniques are also used industrially to test for flaws in metals, to clean surfaces, to test the thickness of parts, and to form colloids.

Chemistry

The study and use of pressure waves that have a frequency in excess of 20 000 Hz and are therefore inaudible to the human ear. Ultrasonics are used in medical diagnosis, particularly in conditions such as pregnancy, in which X-rays could have a harmful effect. Ultrasonic techniques are also used industrially to test for flaws in metals, to clean surfaces, to test the thickness of parts, and to form colloids.

Chemical Engineering

The study of ultrasonic pressure waves for the purposes of testing metals for faults, flaws, and thickness, as well as for surface cleaning. It uses frequencies above audio frequencies and cannot be detected by the human ear. Ultrasonic testing is a non-destructive technique used to identify the thickness of metal such as vessels and pipework, and the presence of corrosion. It uses short pulses of ultrasound with frequencies typically of around 2 MHz.

Electronics and Electrical Engineering

The study and application of sound frequencies that lie above the upper limit of the human hearing range, i.e. frequencies above about 20 kilohertz.
Ultrasonic waves may be generated electronically by magnetostriction generators or piezoelectric generators. In the former case a high-frequency electric oscillation is applied to a material that exhibits magnetostriction so as to produce ultrasonic waves. In the latter the piezoelectric effect transforms the electric oscillations into ultrasonic waves.
Ultrasonic waves may be detected using the hot-wire microphone. The only electrical receiver that is sensitive to ultrasonic waves is the piezoelectric quartz crystal. When excited by an ultrasonic wave that is propagated in a suitable direction and corresponds in frequency to the natural frequency of the receiving crystal, mechanical vibrations are set up in the crystal and produce varying electric potentials. Since two crystals of the same natural frequency are very difficult to obtain, the receiving crystal must be electrically tuned to the frequency of the received wave. A type of detector due to Pierce uses the same piezoelectric crystal as both transmitter and receiver.
Ultrasonic waves have many applications. In electronics the main applications include degassing of melts during the manufacture of electronic components and circuits, cleaning of electronic components, and echo sounding and underwater communication. Ultrasonics is used in medicine for imaging of, for example, a brain tumour or a foetus.

Biology

The study and use of pressure waves that have a frequency in excess of 20 000 Hz and are therefore inaudible to the human ear. Ultrasound is used in medical diagnosis, particularly in conditions such as pregnancy, in which X-rays could have a harmful effect.

单词	ultrasonics
释义	ultrasonics Physics The study and use of pressure waves that have a frequency in excess of 20 000 Hz and are therefore inaudible to the human ear. Ultrasonic generators make use of the piezoelectric effect, ferroelectric materials, or magnetostriction to act as transducers in converting electrical energy into mechanical energy. Ultrasonics are used in medical diagnosis, particularly in conditions such as pregnancy, in which X-rays could have a harmful effect. Ultrasonic techniques are also used industrially to test for flaws in metals, to clean surfaces, to test the thickness of parts, and to form colloids. Chemistry The study and use of pressure waves that have a frequency in excess of 20 000 Hz and are therefore inaudible to the human ear. Ultrasonics are used in medical diagnosis, particularly in conditions such as pregnancy, in which X-rays could have a harmful effect. Ultrasonic techniques are also used industrially to test for flaws in metals, to clean surfaces, to test the thickness of parts, and to form colloids. Chemical Engineering The study of ultrasonic pressure waves for the purposes of testing metals for faults, flaws, and thickness, as well as for surface cleaning. It uses frequencies above audio frequencies and cannot be detected by the human ear. Ultrasonic testing is a non-destructive technique used to identify the thickness of metal such as vessels and pipework, and the presence of corrosion. It uses short pulses of ultrasound with frequencies typically of around 2 MHz. Electronics and Electrical Engineering The study and application of sound frequencies that lie above the upper limit of the human hearing range, i.e. frequencies above about 20 kilohertz. Ultrasonic waves may be generated electronically by magnetostriction generators or piezoelectric generators. In the former case a high-frequency electric oscillation is applied to a material that exhibits magnetostriction so as to produce ultrasonic waves. In the latter the piezoelectric effect transforms the electric oscillations into ultrasonic waves. Ultrasonic waves may be detected using the hot-wire microphone. The only electrical receiver that is sensitive to ultrasonic waves is the piezoelectric quartz crystal. When excited by an ultrasonic wave that is propagated in a suitable direction and corresponds in frequency to the natural frequency of the receiving crystal, mechanical vibrations are set up in the crystal and produce varying electric potentials. Since two crystals of the same natural frequency are very difficult to obtain, the receiving crystal must be electrically tuned to the frequency of the received wave. A type of detector due to Pierce uses the same piezoelectric crystal as both transmitter and receiver. Ultrasonic waves have many applications. In electronics the main applications include degassing of melts during the manufacture of electronic components and circuits, cleaning of electronic components, and echo sounding and underwater communication. Ultrasonics is used in medicine for imaging of, for example, a brain tumour or a foetus. Biology The study and use of pressure waves that have a frequency in excess of 20 000 Hz and are therefore inaudible to the human ear. Ultrasound is used in medical diagnosis, particularly in conditions such as pregnancy, in which X-rays could have a harmful effect.
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