Information Technology Reference
In-Depth Information
Fig. 4.2
Mobile objects (“fish”) moving on a transportation network and passing cordons (Repub-
lished from Both, A., Duckham, M., Laube, P., Wark, T., & Yeoman, J. (2013). Decentralized mon-
itoring of moving objects in a transportation network augmented with checkpoints.
The Computer
Journal, 56
(12), 1432-1449, DOI:10.1093/comjnl/bxs117, by permission of Oxford University
Press.)
discrete
cordon-structured network. Furthermore this systems adheres to the
Eulerian
perspective of movement as the system monitors times when the objects pass the fixed
cordons. The raw information produced by this tracking system consists of
histories
of the states of the moving endurants (i.e. object
o
is located on edge
e
i
). Just as
outlined above, deriving chronicles of transition occurrences requires information
processing.
On top of the transportation network, the formal model furthermore requires a
communication network and a connectivity network. The model assumes one-hop
communications between two types of sensor nodes: the set of moving nodes (fish),
and the set of immobile cordons at known locations. The
communication network
is
then represented as a time-varying undirected graph comprising the one-hop com-
munication links between nearby nodes. As will be shown below, depending on the
application and technologies used these links will vary. Finally, the
connectivity net-
work
represents the relative network locations of cordons in terms of transportation
network connectivity between cordon locations. Cordons can sense the movement of
passing fish. For example in Fig.
4.2
, node 102 senses at
t
2
that fish 5 passes, coming
from node 101 (where it left at
t
1
) and is now heading towards node 103. Finally,
fish may also be able to sense other fish when they pass each other (not depicted in
Fig.
4.2
).
