{'fraction_non_alphanumeric': 0.0232722143864598, 'fraction_numerical': 0.012693935119887164, 'mean_word_length': 6.276923076923077, '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}}
Measurements of electromechanical impedance to determine effects of pressure and temperature on underwater acoustic transducers

Underwater electroacoustic transducers can be subjected to large static pressures, wide range of temperature, and high operational electric fields causing internal heating. These conditions can adversely impact the performance of transducers including transmit output source level, reliability, survivability, useable bandwidth, tuning and matching to the amplifier, and efficiency. A low cost electroacoustic impedance measurement system was implemented with an air-pressurized mechanical transformer using SCUBA tanks to investigate transducer properties to 1,500 PSI. Subsequently, a water pressurized tank was used to 10 000 psi (or 7000 m of equivalent depth). A variety of underwater cylindrical transducers were tested and the changes in electromechanical properties (dielectric constant, capacitance, loss-tangent, mechanical compliance, piezoelectric d-constant, and effective coupling constant) were measured dynamically using the impedance methods. An analytical model was developed with a GUI to predict acoustic performance and tuning for different operational (depth, temperature, and drive level) conditions. Cylindrical transducers of oil-filled and polyurethane filled designs were shown to have moderate changes in electromechanical properties to pressures of 10 000 psi.