document: Shear horizontal (SH) ultrasound waves are guided waves (they have propagation properties affected by the geometry of the propagation medium), with symmetric and anti-symmetric modes; phase and group speeds are dependent on frequency, sample thickness, and the bulk shear wave speed [11,12]. The properties of the different modes can be very useful, such as in thickness measurement [13], but in this case they are a complication. SH0 has a thickness independent speed, equal to the shear wave speed, and is non-dispersive (the phase and group speed are equal to the shear wave speed for all frequencies). The oscillation direction of SH ultrasound is in the plane of the surface where the wave was generated, and perpendicular to the propagation direction, as shown in Fig. 1, with respect to a reference interface, which is typically a sample surface. Under certain conditions, such as over short propagation distances, SH waves can be treated as bulk waves.
doc_bio_tags: O O B I O O B I O O B O O O O O O O B O O O O O O O O O O O O O O O O O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O B I I O O O O B I I I O O O O B I I O O O O B O O B I O O O O O O O O O B O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O B O B I O O O O B I
extractive_keyphrases: bulk shear wave speed bulk waves guided waves oscillation phase and group speed propagation sh0 shear wave speed sh ultrasound sh waves wave
abstractive_keyphrases: shear horizontal (sh) ultrasound waves