99,429 research outputs found
Finding shortest and nearly shortest path nodes in large substantially incomplete networks
Dynamic processes on networks, be it information transfer in the Internet,
contagious spreading in a social network, or neural signaling, take place along
shortest or nearly shortest paths. Unfortunately, our maps of most large
networks are substantially incomplete due to either the highly dynamic nature
of networks, or high cost of network measurements, or both, rendering
traditional path finding methods inefficient. We find that shortest paths in
large real networks, such as the network of protein-protein interactions (PPI)
and the Internet at the autonomous system (AS) level, are not random but are
organized according to latent-geometric rules. If nodes of these networks are
mapped to points in latent hyperbolic spaces, shortest paths in them align
along geodesic curves connecting endpoint nodes. We find that this alignment is
sufficiently strong to allow for the identification of shortest path nodes even
in the case of substantially incomplete networks. We demonstrate the utility of
latent-geometric path-finding in problems of cellular pathway reconstruction
and communication security
Dynamic Resource Reservation and Connectivity Tracking to Support Real-Time Communication among Mobile Units
Wireless communication technology is spreading quickly in almost all the information technology areas as a consequence of a gradual enhancement in quality and security of the communication, together with a decrease in the related costs. This facilitates the development of relatively low-cost teams of autonomous (robotic) mobile units that cooperate to achieve a common goal. Providing real-time communication among the team units is highly desirable for guaranteeing a predictable behavior in those applications in which the robots have to operate autonomously in unstructured environments. This paper proposes a MAC protocol for wireless communication that supports dynamic resource reservation and topology management for relatively small networks of cooperative units (10–20 units). The protocol uses a slotted time-triggered medium access transmission control that is collision-free, even in the presence of hidden nodes. The transmissions are scheduled according to the earliest deadline first scheduling policy. An adequate admission control guarantees the timing constraints of the team communication requirements, including when new nodes dynamically join or leave the team. The paper describes the protocol focusing on the consensus procedure that supports coherent changes in the global system. We also introduce a distributed connectivity tracking mechanism that is used to detect network partition and absent or crashed nodes. Finally, a set of simulation results are shown that illustrate the effectiveness of the proposed approaches
Spreading processes in Multilayer Networks
Several systems can be modeled as sets of interconnected networks or networks
with multiple types of connections, here generally called multilayer networks.
Spreading processes such as information propagation among users of an online
social networks, or the diffusion of pathogens among individuals through their
contact network, are fundamental phenomena occurring in these networks.
However, while information diffusion in single networks has received
considerable attention from various disciplines for over a decade, spreading
processes in multilayer networks is still a young research area presenting many
challenging research issues. In this paper we review the main models, results
and applications of multilayer spreading processes and discuss some promising
research directions.Comment: 21 pages, 3 figures, 4 table
Secure and Reconfigurable Network Design for Critical Information Dissemination in the Internet of Battlefield Things (IoBT)
The Internet of things (IoT) is revolutionizing the management and control of
automated systems leading to a paradigm shift in areas such as smart homes,
smart cities, health care, transportation, etc. The IoT technology is also
envisioned to play an important role in improving the effectiveness of military
operations in battlefields. The interconnection of combat equipment and other
battlefield resources for coordinated automated decisions is referred to as the
Internet of battlefield things (IoBT). IoBT networks are significantly
different from traditional IoT networks due to the battlefield specific
challenges such as the absence of communication infrastructure, and the
susceptibility of devices to cyber and physical attacks. The combat efficiency
and coordinated decision-making in war scenarios depends highly on real-time
data collection, which in turn relies on the connectivity of the network and
the information dissemination in the presence of adversaries. This work aims to
build the theoretical foundations of designing secure and reconfigurable IoBT
networks. Leveraging the theories of stochastic geometry and mathematical
epidemiology, we develop an integrated framework to study the communication of
mission-critical data among different types of network devices and consequently
design the network in a cost effective manner.Comment: 8 pages, 9 figure
Optimal Vaccine Allocation to Control Epidemic Outbreaks in Arbitrary Networks
We consider the problem of controlling the propagation of an epidemic
outbreak in an arbitrary contact network by distributing vaccination resources
throughout the network. We analyze a networked version of the
Susceptible-Infected-Susceptible (SIS) epidemic model when individuals in the
network present different levels of susceptibility to the epidemic. In this
context, controlling the spread of an epidemic outbreak can be written as a
spectral condition involving the eigenvalues of a matrix that depends on the
network structure and the parameters of the model. We study the problem of
finding the optimal distribution of vaccines throughout the network to control
the spread of an epidemic outbreak. We propose a convex framework to find
cost-optimal distribution of vaccination resources when different levels of
vaccination are allowed. We also propose a greedy approach with quality
guarantees for the case of all-or-nothing vaccination. We illustrate our
approaches with numerical simulations in a real social network
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