Information Technology Reference
In-Depth Information
a
8
t
i
-6
a
7
t
i
-1
a
2
a
5
a
5
a
1
a
1
c
a
4
a
7
a
8
a
4
a
2
t
i
-5
t
i
a
2
a
1
a
7
a
8
a
5
a
5
a
7
a
1
a
8
a
4
a
2
a
4
t
i
-4
memory
a
2
a
1
a
5
a
7
a
8
a
2
a
1
a
5
a
8
a
4
a
7
t
i
t
i
-1
t
i
-2
t
i
-3
t
i
-4
t
i
-5
t
i
-6
a
4
deferral
d
t
i
-3
a
5
w
a
8
a
7
flock
contiguity
k
p
a
4
a
1
a
2
t
i
-2
a
5
flock!
a
8
known to
a
2
at
t
i
, flocking
a
1
a
7
a
4
a
2
known to
a
2
at
t
i
, not flocking
unknown to
a
2
at
t
i
Fig. 4.5
The deferred data mining in
DDIG
. A heuristic is used to find flocks in the local mem-
ory
a
2
. A flock is detected for
[
t
i
−
6
,...,
t
i
−
4
]
. Note that, given the deferred processing and the
information stored in memory,
a
2
finds flocks even with neighbors it is not connected anymore at
t
i
(Republished from Laube, P., Duckham, M., & Palaniswami, M. (2011). Deferred Decentral-
ized Movement Pattern Mining for Geosensor Networks.
International Journal of Geographical
Information Science, 25
(2), 273-292, Taylor & Francis, DOI:10.1080/13658810903296630.)
representation. Any preexisting knowledge can be exploited that contributes to solv-
ing a decentralized spatial computing task with its rather demanding preliminaries.
Such knowledge can involve constraints to the movement (for example, nodes must
move on the edges of a transportation network) or properties of the monitored phe-
nomenon (for example, spatio-temporal autocorrelation of the movement parameters
of flocking animals).
The following discussion illustrates that in decentralized spatial computing the
boundaries between the previously separated tasks
data capture
,
communication
and
computation
become increasingly blurred (
P8
. Laube and Duckham
2009
; Kargupta
and Chan
2000
). After a short recapitulation of the threats facing decentralized move-
ment analysis, four opportunities arising mobility in geosensor networks are listed
and exemplified in the context of decentralized movement analysis. The section con-
cludes with a short discussion of the implications of these opportunities for decen-
tralized movement analysis with respect to decentralization issues not specific to
movement.
