Design and test a surrogate unexploded ordnance (UXO) that can be placed in a scenario of interest and provide the bottom properties over an estimated footprint from the same measurement procedure used to search for UXO’s in the mid-frequency regime.
A previously developed formulation of scattering from media loaded configurations which separates unloaded properties of UXO object from specific medium will be applied to design a surrogate UXO that is sensitive to the medium loading when placed on the bottom. The design involves a time domain finite element methodology that will optimize the unique scattering response with respect to geoacoustic ocean bottom properties over a broadband midfrequency regime with an associated estimate of the footprint of the validity of the inversion for the bottom parameters. The numerical investigation will also include a sensitivity analysis to study the target’s response versus sea-floor clutter, as well as further simulations to examine the effect of sea-floor roughness on the quality of the estimated properties. A scaled model experiment will be constructed to test the object utility for the bottom inversion.
As opposed to standard operating procedures in which sea floor properties are separately determined independent of their object scattering-loading and the extent of the footprint of the properties, this method, utilizing a surrogate UXO, specifically measures the seafloor properties as “seen” through its loading of the object and subsequent broadband scattering response. The desired/expected results are the relevant seafloor parameters and an estimate of the footprint of the measurement.