what-when-how
In Depth Tutorials and Information
qualitative characteristics of networks that make routing with local data gov-
ernable, and providing a model for reasoning about effective routing schemes in
those networks. He believes that a more general conclusion can be drawn about
the small-world network, which is that “correlation between local structure and
long-range connections provides fundamental cues for finding paths through the
network.” When this correlation is near a certain threshold, a gradient is formed
along the long-range connections that helps individuals send the message quickly
toward the target. As the correlation drops below the threshold, these hidden clues
begin to die away until the long-range contacts become uniformly distributed and
the individuals become disoriented. he short paths still exist, but the individuals
are not able to find them.
5.5 Large-ScaleModels[4,6]
A diferent type of social networking model focuses on large-scale networks. hese
large networks can be found in transportation systems, electric power grids, pub-
lic health, and even the Internet. A rising common name for these networks are
“sociotechnical systems,” where one or more social networks interact with one or
more physical networks. In Barret et al. [4], the authors discuss the simulation and
modeling approaches of the Basic and Applied Simulation Science group at Los
Alamos National Laboratory.
he extremely detailed simulations that they have developed (see Figure 5.11)
allow individual agents to interact among themselves as well as the network envi-
ronment and infrastructure. hey also state that their results show that simulation-
based methods are both necessary and sufficient for understanding the dynamics
of such complex systems. hese systems must be studied with the knowledge that,
unlike physical systems, sociotechnical systems are affected not only by physical
laws but also by human behavior, regulatory agencies, and government and private
enterprise (Figure 5.11).
An example of why it is important to be able to model these systems is the
recent failure of the electric power grid in northeastern United States. his failure
affected Internet traffic, closed down financial institutions, and threw transporta-
tion systems out of control. A simulation model can show how all of these systems
are related in a network. he simulation proposed by the authors covers transporta-
tion, urban population mobility, public health, telecommunication, and commod-
ity markets.
hese simulations are based on a formal mathematical and computational the-
ory of sociotechnical simulations, along with unique methods for the design and
analysis of large dynamic networks, and efficient data compression and regenera-
tion techniques. he networks studied are extremely large, consisting of millions of
agents and paths. hese simulations are able to represent the interactions of these
agents in great detail.
