Searching for, detecting and classifying unexploded ordnance (UXO) with sonars operating in underwater environments at least several meters in depth is the subject of this webinar. In general, targets that would be encountered include both proud and buried UXO of different sizes and types and both man-made and natural clutter. Commercial high resolution imaging sonars operating in such environments readily detect most proud targets classifying them using high resolution images. Buried targets are not generally accessible to these sonars because of the high acoustic absorption of the sediment at these high frequencies. So called "structural acoustic (SA)" sonars operate at frequencies two orders of magnitude lower, where sound readily penetrates the sediment exposing buried targets. Further, their wavelengths being about the target size leads to SA frequency/angle responses (acoustic color) whose features can be used for classification. Data taken using the buried object scanning sonar (BOSS) off the coast of Panama City, FL, allows us to examine how effective such SA sonars can be in forming acoustic color classification features and SAS-processed images of buried targets. Technical issues remaining to be addressed include the development of practical methods for training the classification algorithms using a-priori data and/or high fidelity numerical simulations.
Recently, the Acoustical Society of America (ASA) organized a special session on "Understanding the Target/Waveguide System – Measurements and Modeling". The session included presenters from six organizations that have been studying various aspects of the underwater UXO detection and classification problem. The presentations were organized so as to present the entire processing chain from basic physics modeling and data acquisition to final ROC curves generated from classification tests. This presentation will provide a perspective, based on these talks, as to the current state of the art of UXO classification via low frequency acoustics. This perspective is meant only as an entry point into some of UXO-related efforts. The audience is referred to the other speakers at the ASA meeting for both different perspectives and details of their work. In addition, there are many other researchers, particularly in Europe, whose work was not represented at ASA.
Dr. Joseph Bucaro is a senior research scientist with EXCET, Inc. under contract with the Naval Research Laboratory in Washington, D.C. Joe's current areas of research include the development of structural acoustic technologies for the detection and classification of underwater targets and the development of fiber-optic based directional acoustic sensors. Joe has served as Principal Investigator on several SERDP projects seeking to exploit structural acoustics for detecting UXO buried in the underwater sediment and separating these detections into UXO versus clutter. He has authored/co-authored more than 120 refereed journal articles, holds 26 U.S. Patents, and has given hundreds of scientific presentations – all covering a broad spectrum of science and technology ranging from molecular interactions in fluids, optical fiber acoustic sensor technology, sound scattering from underwater structures, active sound control, and structural acoustic-based sonars. He earned his bachelor's and master's degrees in Physics from John Carroll University in University Heights, OH, in 1965 and 1967, respectively, and his Ph.D. in Physics from The Catholic University of America in Washington, D.C., in 1970. Prior to joining EXCET, Inc., Joe had a long career at the Naval Research Laboratory where he both participated in, and managed, hundreds of research programs in Physical Acoustics.
Dr. Kevin Williams received his B.S., M.S. and Ph.D. degrees in physics from Washington State University, Pullman, in 1979, 1983 and 1985, respectively. His Ph.D. thesis examined underwater acoustic scattering from elastic spheres. He worked at the Naval Surface Warfare Center (NSWC) in Panama City, FL, from 1985 to 1988, where he focused on acoustic scattering from finite bodies and propagation into ocean sediments. In 1988, he moved to the Applied Physics Laboratory, University of Washington, Seattle (APL-UW), where he has worked in the areas of underwater environmental and target acoustics. His environmental acoustics efforts have included studies of propagation through ocean internal waves, arctic ice and ocean sediments. His target scattering efforts have centered on understanding the response of targets when placed within an ocean waveguide. He has lead multiple ocean field experiments in which the equipment used has been conceived, designed and fielded in close collaboration with the Ocean Engineering Department at APL-UW. The analysis of this field data has included both analytical and finite element methods, carried out in collaboration with other researchers at APL-UW, as well as investigators at Washington State University, NSWC and TNO Defense in the Netherlands. He is currently a Senior Principal Physicist and the Chairman of the Ocean Acoustics Department. Dr. Williams is a Fellow of the Acoustical Society of America.