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Experimentation and Calibration
APS provides a wealth of expertise in planning and executing acoustic experiments as well as providing detailed, post-test data analysis. Our laboratory features a custom-built standing wave tube to provide preliminary calibration of hydrophones. We have directed laboratory experiments of submarine piping system mock-ups with sensor counts in excess of 1,000, have built lightweight airborne acoustic sensing systems deployed from aerostat balloons, and demonstrated an acoustic array-based measurement system to automatically discriminate wind noise from artillery and small arms fire. APS offers a unique expertise in nearfield-to-farfield algorithm development, a key element for calibrating relatively large sonars and predicted farfield radiation from submerged structures. A recently develop nearfield holography algorithm was used to predict full-scale radiated signatures of next generation surface ship hulls using nearfield measurements of scale models. A particular specialty at APS is array-based experimentation, which is useful for understanding wave propagation, scattering and dissipation mechanisms in complex structures. APS’ logo is derived from an image plot of output from a distributed accelerometer array measuring the forced response of a fluid filled elastic cylinder. The data are displayed as an axial wavenumber – frequency domain spectrum, which is computed via a two-dimensional Fourier transform of data collected in the axial location – time domain. The APS logo clearly reveals the classic “candelabra” pattern of the modal bending dispersion relations for thin cylindrical shells, and is a symbolic reminder of our expertise in the physics, mathematics and experimental approaches of wave propagation.
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