{'fraction_non_alphanumeric': 0.017973856209150325, 'fraction_numerical': 0.011437908496732025, 'mean_word_length': 4.951456310679611, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
High Velocity Acoustical Head Wave on Surface of ST Quartz

According to surface transient excitation theory of elastic wave for piezoelectric crystal, in the surface of a piezoelectric crystal can exist acoustical high velocity head wave except the general surface acoustic wave (SAW). Such a mode is to propagate with the group velocity of the longitudinal bulk wave along the crystal surface. For ST quartz its value is 5.744×103 m/s, which agrees with our experiments. The fact that the longitudinal head wave mode has a high propagation velocity offers potential applications for high frequency SAW devices.