Timothy J. Yoder

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ÐMultiaspect target identification is effected by fusing the features extracted from multiple scattered waveforms; these waveforms are characteristic of viewing the target from a sequence of distinct orientations. Classification is performed in the maximum-likelihood sense, which we show, under reasonable assumptions, can be implemented via a hidden Markov(More)
Identification algorithms are considered for a class of targets situated near the bottom of a water channel. It is assumed that the target-sensor distance relative to the channel depth is such that a ray-based representation of the scattered fields is appropriate (vis-à-vis a modal representation). Two approaches are considered for processing the scattered(More)
Time-reversal is addressed for imaging elastic targets situated in an acoustic waveguide. It is assumed that the target-sensor range is large relative to the channel depth. We investigate the theory of wideband time-reversal imaging of an extended elastic target, for which the target dimensions are large relative to the principal wavelengths. When(More)
Using a finite element-based structural acoustics code, simulations were carried out for the acoustic scattering from an unexploded ordnance rocket buried in the sediment under 3 m of water. The simulation treated 90 rocket burial angles in steps of 2°. The simulations were used to train a generative relevance vector machine (RVM) algorithm for identifying(More)
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(More)
Laboratory underwater bistatic scattering measurements are reported for free, proud, and half-buried unexploded ordnances for 0 degrees and 90 degrees source angles. Forward echoes are larger than backscattered returns, and half burial significantly decreases the latter but not the former. Results agree with analytic predictions borrowed from radar. The(More)
The broadband bistatic target strengths (TSs) of two submerged unexploded ordnance (UXO) targets have been measured in the NRL sediment pool facility. The targets-a 5 in. rocket and a 155 mm projectile-were among the targets whose monostatic TSs were measured and reported previously by the authors. Bistatic TS measurements were made for 0 degrees (target(More)
In order to evaluate the potential for detection and identification of underwater unexploded ordnance (UXO) by exploiting their structural acoustic response, we carried out broadband monostatic scattering measurements over a full 360 degrees on UXO's (two mortar rounds, an artillery shell, and a rocket warhead) and false targets (a cinder block and a large(More)
Individuals with brain cancer face many challenges, including threats to cognition, personality, and sensory and motor functioning. These can alter one's sense of identity and result in despair. Chaplain-led spiritual interviews were conducted with 19 patients with brain cancer as part of a larger spiritual legacy intervention called "Hear My Voice." The(More)
Time-reversal is addressed for imaging and classifying elastic targets situated in an acoustic waveguide. It is assumed that the target-sensor range is large relative to the channel depth. We first investigate the theory of wideband time-reversal imaging of an extended elastic target for which the target dimensions are large relative to the principal(More)