title: Bistatic, above-critical angle scattering measurements of fully buried unexploded ordnance (UXO) and clutter.
abstract: Laboratory grade bistatic scattering measurements are conducted in order to examine the acoustic response of realistic fully buried unexploded ordnance (UXO) from above-critical angle insonification, between 2 and 40 kHz. A 127 mm diameter rocket UXO, a 155 mm diameter artillery shell, a natural rock of approximately the same size, and a cinder block are fully buried in water-saturated medium grained sand (mean grain diameter, 240 μm) at depths of 10 cm below the water-sediment interface. A two-dimensional array of bistatic scattering measurements is generated synthetically by scanning a single hydrophone in steps of 3 cm over a 1 m × 1 m patch directly above the targets at a height of 20 cm above the water-sediment interface. Three-dimensional volumetric acoustic images generated from the return waveforms reveal scattering components attributed to geometric and elastic scattering, as well as multiple-scattering interactions of returns between the sediment-water interface and the buried objects. The far-field target strength of the objects is estimated through extrapolation of the angular spectrum. Agreement is found between experimental data and simulated data generated from a finite-element-based, three-dimensional time-harmonic model (2-25 kHz). Separation of the measured UXO from the clutter objects is demonstrated through exploitation of structural-acoustics-based features.
authors.affiliation: Naval Research Laboratory, Code 7130, Washington, DC 20375, USA. zachary.waters@nrl.navy.mil
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Waters
authors.forename: H J
authors.initials: HJ
authors.lastname: Simpson
authors.forename: A
authors.initials: A
authors.lastname: Sarkissian
authors.forename: S
authors.initials: S
authors.lastname: Dey
authors.forename: B H
authors.initials: BH
authors.lastname: Houston
authors.forename: J A
authors.initials: JA
authors.lastname: Bucaro
authors.forename: T J
authors.initials: TJ
authors.lastname: Yoder
mesh_terms: D000162:Acoustics / Q000295:instrumentation; D003198:Computer Simulation; D020342:Finite Element Analysis; D005389:Firearms; D005583:Fourier Analysis; D019015:Geologic Sediments; D008962:Models, Theoretical; D009038:Motion; D009716:Numerical Analysis, Computer-Assisted; D012542:Scattering, Radiation; D012815:Signal Processing, Computer-Assisted; D012822:Silicon Dioxide; D013016:Sound; D013018:Sound Spectrography; D013997:Time Factors; D014159:Transducers; D014867:Water
chemical_list: D014867:Water; D012822:Silicon Dioxide