INTERIM REPORT - Strategic Environmental Research and ...

(a) (b) (c)
Fig. 5. (a) This plot shows the sequential choice transmitter’s activations for uniform sampling for a buried
4.2inch mortar (ID:1006). The choice of the transmitters are shown in red circles and their chronological indices
are numbered in red. Uniform sampling used 18 out of 25 available transmitters to obtain an accurate estimate of
anomaly features. (b) This plot shows the variation of feature estimation error as a function of sensing actions.
Active selection and uniform selection are shown in red and blue, respectively. Active learning achieves the desired
accuracy using only six sensing action compared to eighteen actions taken by uniform sampling. (c) The adaptively
selected transmitter sequence is shown in this plot, where the chronological indices are numbered in red.
constraining since there exists only sixteen discrete locations at which a 2x2 sensor block could be
positioned. However, SIG is aware that a hand-held version of the TEMTADS system (consisting of
four transmitters and four receivers arranged in a 2x2 array) is currently being developed by Dr. Tom
Bell and his colleagues at SAIC, funded by a separate SERDP program. The same group at SAIC
is also developing a single transmitter-receiver coil system to be operated in hand-held configuration.
It is supposed to collect data on a fixed grid placed above a buried anomaly. We think that the data
collected by these systems would be helpful to validate our algorithm in the near future. At the current
stage, SIG wanted to show the following analysis as a proof of concept given the small dataset that is
already collected at Camp SLO. In the near future, SIG hopes to access data collected by the hand-held
TEMTADS system and validate our approach on a more robust dataset.
In the hand-held environment, we assume that there will be a handheld system with four transmitters
and four receivers arranged in a 2x2 array. Once a location is deemed “relevant” by the adaptive sensing
algorithm, all four transmitters would be activated and anomaly responses would be recorded at all four
receivers. Based on the collected data, SIG will estimate the model parameters and identify the next
“best” location for the system to collect data. Since data are already collected on a 5x5 grid, SIG could
only simulate the movement of the sensor system over the twenty-five point grid.
Figure 6 depicts the procedure that is followed to simulate a hand-held environment within the restriction
of already collected data. Figure 6(a) shows the picture of a 4.2inch mortar (ID:1032) after it is excavated
from the ground. Figure 6(b) shows the choice of the first 2x2 Tx-Rx block. Note that we already have data
over a 5x5 grid, where the location of the transmitters are shown in green. The red square encompasses
four adjacent transmitter locations (indexed as [1 2 6 7]), denoting that these transmitters and receivers
were employed to collect data at this location. Figure 6(c) shows the choice of first two locations, where
the second location involves transmitters [11 12 16 17]. Note that one location cannot be chosen more
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