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Next Generation Optical Access Networks |
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When
Friday, 8th January 2010
9:30 a.m.
Where
Central Campus
Department of Electrical and Computer Engineering
Room A106 (old Senate Room)
Speaker
Georgios Ellinas
This presentation is organized by the Department of Electrical and Computer Engineering.
Abstract
The presentation focuses on the development of fully-distributed,
survivable multiservice Passive Optical Network (PON)-based access
networking architectures that efficiently transport and support a wide
range of existing and emerging fixed-mobile advanced multimedia
applications and services along with the diverse quality of service
(QoS), rate, and reliability requirements set by these services. The
main characteristic of the proposed architectures is that they support
a fully distributed control plane among the Optical Networking Units
(ONU)s, which enables efficient resource utilization and also allows
each and every ONU to independently detect, manage, and recover most of
the networking failure scenarios. Several distributed resource
allocation and scheduling algorithms will be presented for the
distributed PON architectures that fairly and efficiently support
dynamic allocation of network resources and sharing traffic among
end-users. Distributed fault detection and recovery schemes will also
be discussed that are capable of protecting against both node and
distribution/trunk fiber failures, including any combination of
concurrent double failures. These schemes enable the restoration of all network traffic including upstream,
downstream, and LAN data. The presentation will also focus on the
requirements for the converged optical/wireless access architectures
and will demonstrate how the proposed architecture meets these
requirements.
About the Speaker
Georgios Ellinas holds B.S., M.S., M.Phil., and Ph.D. degrees in
electrical engineering from Columbia University, U.S.A.. He is
currently an Assistant Professor of Electrical and Computer Engineering
at the University of Cyprus. Prior to joining the University of Cyprus
he was an Associate Professor of Electrical Engineering at City College of the City University of New
York (2002-2005). Before joining the academia, he was a Senior Network
Architect at Tellium (2000-2002), and a Senior Research Scientist in
Telcordia Technologies’ (formerly Bell Communications Research) Optical
Networking Research Group where he performed research for the
DARPA-funded Optical Networks Technology Consortium (ONTC), multi wave length Optical Networking (MONET) and Next Generation Internet
(NGI) projects from 1993 to 2000. He has co-authored two books on
optical networking (Cambridge University Press 2008, Wiley 2007) and
more than 110 journal and conference papers, and is also the holder of
29 patents on optical networking. His research interests are in the
areas of optical architectures, unicast/multicast/groupcast routing and
wavelength assignment algorithms, traffic grooming, fault protection/restoration techniques
in arbitrary mesh optical networks, optical access networks, converged
optical-wireless access networks, critical infrastructure systems, and
complex networks.
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Census and Survey of the Visible Internet |
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When
Tuesday, December 22st, 2009
11:30-12:30 EET
Where
Building 12 Faculty of Pure and Applied Sciences,
New Campus,
Room 148
Speaker
Prof. Christos Papadopoulos
Colorado State University, USA
This seminar is organized by the Department of Computer Science at the University of Cyprus. Abstract
Many Internet topology studies have appeared in the literature. However, such
studies have for the most part, ignored the population of hosts. While many
hosts are hidden behind firewalls and NATs, there is much to be learned from
examining the population of "visible" Internet hosts -- one can
better understand network growth and accessibility to help assess
vulnerabilities, deployment of new technologies and improve network models.
This paper is to our knowledge the first attempt to measure the population of
visible Internet edge hosts. We measure hosts in two ways: via periodic
Internet censuses, where we query all accessible Internet addresses every few
months, and via surveys of a small fraction of the responsive address space,
probing each address every 11 minutes for one week. These approaches are
complementary: a census is effective at evaluating the Internet as a whole,
while surveys validate the census and allow observation of the lifetime of
typical address occupancy.
Our findings include trends in address occupancy, an upper bound on the number
of servers and an analysis of firewalled addresses and firewall block size.
Joint work with John Heidemann, Yuri Pryadkin, Ramesh Govindan and Joseph
Bannister. |
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A Game for Optimizing Randomized Patrols on a Network |
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When
Monday, December 21st, 2009
11:00-12:00
Where
Building 12 Faculty of Pure
and Applied Sciences,
New Campus,
Room 148
Speaker
Dr. Katerina Papadaki
London School of Economics, UK
This seminar is organized by the Department of Computer Science at the University of Cyprus. Abstract
This paper describes a class of patrolling games on graphs, motivated
by the
problem of patrolling a network vulnerable to viral infection or a
facility
(for example in order to defend an art gallery against theft of a
painting, or
an airport against terrorist attack). The network/facility can be
thought of as
a graph Q of interconnected nodes (e.g. rooms, terminals) and the
Attacker can
choose to attack any node of Q within a given time T. He requires m
consecutive
periods there, uninterrupted by the Patroller, to commit his nefarious
act (and
win). The Patroller can follow any path on the graph. Thus the
patrolling game
is a win-lose game, where the Value is the probability that the
Patroller
successfully intercepts an attack, given best play on both sides. We
determine
analytically optimal (minimax) patrolling strategies for various
classes of
graphs, and present numerical results for some intractable cases.
Joint work with Steve Alpern and Alec Morton |
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Fault Diagnosis and Security Monitoring in Water Distribution Systems |
When
Thursday, 12 November 2009
13:30-14:30
Where
Green Park GP414
Speaker
Demetrios Eliades
Proposal of PhD defence
Abstract
Water
resources management is a key challenge that will become even more
crucial in the years ahead. Water distribution systems are responsible
for delivering clean water to consumers, and have an important role in
sustaining certain vital societal functions. When a system fault
occurs, such as water contamination or a pipe break, these societal
functions may be affected negatively. In the previous years, various
aspects of the security monitoring problem in water distribution
systems have been examined; in addition, robust fault diagnosis
algorithms have been developed within a system-theoretic framework. An
open research area is the formulation of a system-theoretic framework
suitable for fault diagnosis and security monitoring in water
distribution systems; this is the general goal of this work. In
specific, this work has four objectives. The first objective aims to
formulate the monitoring and control problem of water distribution
networks, in a framework suitable for sensor placement and fault
diagnosis. The second objective is to find those locations in a water
distribution network, where on-line quality sensors should be
installed, in order to minimize the risk of a severe damage on the
population; a special case is the problem of manual quality sampling
scheduling, for finding where and when to take water samples to check
its quality. The third objective is to design fault detection
algorithms, so that a contaminant substance is detected by monitoring
its reaction dynamics, by using a model-based fault diagnosis approach.
An adaptive approximation model, such as a neural network, is activated
after a fault has been detected, to learn the unknown fault dynamics.
Furthermore, the source location of the contamination fault is
estimated by considering the previous and future hydraulic dynamics.
Finally, the fourth objective is to design fault accommodation
algorithms which change the disinfectant concentration controller
input, to accommodate the contamination fault and return the system to
safe operation.
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