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Ultrasound is defined by the American National Standards Institute as "sound at frequencies greater than 20 kHz". In air at atmospheric pressure, ultrasonic waves have wavelengths of 1.9 cm or less. Ultrasound can be generated at very high frequencies; ultrasound is used for sonochemistry at frequencies up to multiple hundreds of kilohertz.
Schlieren imaging is a method to visualize density variations in transparent media. [1]Schlieren imaging of a focusing ultrasonic transducer Schlieren image sequence of a bullet traveling in free-flight, demonstrating the air pressure dynamics surrounding the bullet
Isochoic wave is a term used in ultrasound. Substances of a different medium are called isochoic if waves travel through them at the same speed. Isochoic in ultrasound means that two structures have the same echogenicity in 2D mode (B-mode).
Ultrasound energy, simply known as ultrasound, is a type of mechanical energy called sound characterized by vibrating or moving particles within a medium. Ultrasound is distinguished by vibrations with a frequency greater than 20,000 Hz, compared to audible sounds that humans typically hear with frequencies between 20 and 20,000 Hz.
Ultrasound attenuation measurement in heterogeneous systems, like emulsions or colloids, yields information on particle size distribution. There is an ISO standard on this technique. [3] Ultrasound attenuation can be used for extensional rheology measurement. There are acoustic rheometers that employ Stokes' law for measuring extensional ...
Introduction to the Physics of Sound; Hearing curves and on-line hearing test; Audio for the 21st Century Archived 2009-01-23 at the Wayback Machine; Conversion of sound units and levels; Sound calculations; Audio Check: a free collection of audio tests and test tones playable on-line; More Sounds Amazing; a sixth-form learning resource about ...
The generation lasers are short pulse (from tens of nanoseconds to femtoseconds) and high peak power lasers. Common lasers used for ultrasound generation are solid state Q-Switched Nd:YAG and gas lasers (CO 2 or Excimers). The physical principle is of thermal expansion (also called thermoelastic regime) or ablation. In the thermoelastic regime ...
Resonant ultrasound spectroscopy (RUS) is a laboratory technique used in geology and material science to measure fundamental material properties involving elasticity. This technique relies on the fact that solid objects have natural frequencies at which they vibrate when mechanically excited.