Aerospace & Defense Technology - October 2021 - 32

Tech Briefs
rectly assess the condition of dunes and
other natural coastal infrastructure. For example,
Brodie and Spore (2015) compared
CLARIS data against insight from Hesp
(2002) to classify dune health by measuring
their slopes, volumes, and curvature.
The data will also support the development
of better models for wave runup,
coastal inundation, and overall sediment
transport by providing more data for
model input and validation, particularly
across larger, regional scales.
This work was done by Nicholas J. Spore,
Alexander D. Renaud, Ian W. Conery, and
Katherine L. Brodie for the Army Engineer Research
and Development Center. For more
information, download the Technical
Support Package (free white paper) at
www.aerodefensetech.com/tsp under the
DAQ, Testing & Sensors category. (ERDC0011)
Development
and Testing of a New Version of Mbud for
Cued Classification of Marine UXO
Improved version of the Marine UXO characterization system, MBUD, has a new data acquisition system and
incorporates technical modifications to eliminate the noise encountered in seawater with the MBUD1 version.
Strategic Environmental Research and Development Program, Alexandria, Virginia
T
here continues to be a need for an
electromagnetic induction (EMI) system
that can characterize unexploded
ordnance (UXO) in the marine environment.
There are many areas in the millions
of acres that host underwater UXO.
The US Army Corps of Engineers has identified
400 underwater formerly used defense
sites. These sites all have munitions
or UXO in less than 40m of water. A sizedepth
plot typical for these UXO from DiMarco
et al. (2010) was used as a design
guide for the first MBUD system and is reproduced
here as Figure 1. A compilation
of polarizability calculations from a variety
of targets for BUD and MBUD is
shown by the dashed line in Figure 1. This
line indicates that the MBUD system can
effectively classify most targets to a depth
of about 1.2 m.
Currently wide-area assessment is carried
out using low and high-frequency
acoustic and magnetometer arrays, both
of which must be moved over the area at
some distance above the sea bottom. The
magnetic response of small targets decreases
rapidly with increasing distance
from the object. Further magnetometer
surveys can be ineffective if the sea bottom
has magnetic rock, sand, or gravel (as
is common in Hawaii). Low-frequency
acoustic scanners have low resolving
power for small targets beneath the bottom
and may not be effective in water
depths of less than 3-5m.
Low-frequency acoustic scanning
methods may eventually be able to
characterize buried medium to large ob32
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Figure 1. Size vs. depth plot for marine UXO (from DiMarco et al., 2010). Superimposed is the size-depth
limit for polarizability resolution for the MBUD system.
jects, but at present, they can only locate
small objects as point scatterers.
EMI systems must be operated on the
bottom, and in many locations this is
difficult or impossible. Quoting from a
recent SERDP symposium, " EMI technology
will probably be restricted to
cued classification " and eventually will
be deployed with a commercial midsized
ROV. MBUD2 is well-suited for
www.aerodefensetech.com
ToC
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this role. The performance of MBUD2
was demonstrated on land and in San
Francisco Bay. MBUD2 was operated in
a cued mode - the system was stationery
and targets were placed in various
locations by an operator (on land)
or a diver (in San Francisco Bay).
A simple open frame MBUD2 prototype
system configuration consists of
four, three-component, receiver cubes
Aerospace & Defense Technology, October 2021
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Aerospace & Defense Technology - October 2021

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