| FALL 2007 |
Sep-6-2007
11:00AM
1410 PEC
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Speaker:
Dr. Hassan Artail
Associate Professor
Department of Electrical and Computer Engineering
American University of Beirut (AUB)
Topic:Collaborative and Distributed Semantic Caching for MANETs
Abstract:
Mobile Ad-Hoc Networks (MANETs) are receiving great
attention because of their easy deployment and potential applications.
Mobile
nodes in MANETs acquire data from data servers through access points.
Each
mobile node in a MANET sends a request to the access point each time it
needs
data. In order to avoid this costly operation, data caching at mobile
nodes is
employed. Several caching techniques for MANETs have been proposed and
implemented. Cooperative and Adaptive Caching is a recent
directory-based
caching scheme that separates the query from its response and caches
each one
on a specific node in the network. When a new request is issued, nodes
cooperate to find its answer and send it to the requesting node. In
this work,
we additionally apply semantic caching by semantically comparing each
submitted
request with all cached queries. The semantic analysis process may
include
trimming the request into fragments and combining the answers of these
fragments to calculate the total answer of the request. Mathematical
analysis
and experimental results prove the viability of the proposed system in
terms of
query response time, generated traffic, and hit ratio. |
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FALL
2006
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Sep-13-2006
11:00AM
121 CIS
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Speaker: Dr. Zhen-Jun Shi
Topic: Optimization and Its Applications
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Sep-21-2006
10:30AM
121 CIS |
Speaker: Mr. Nathan Balon
Topic: Increasing Broadcast Reliability in Vehicular Ad Hoc Networks
Abstract: Broadcast transmissions are the predominate form of
network traffic in a VANET. However, since there is no MAC-layer
recovery on broadcast frames within an 802.11-based VANET, the
reception rates of broadcast messages can become very low, especially
under saturated conditions. In this paper, we present an adaptive
broadcast protocol that improves the reception rates of broadcast
messages. We rely on the observation that a node in a VANET is
able to detect network congestion by simply analyzing the sequence
numbers of packets it has recently received. Based on the percentage of
packets that are successfully received in the last few seconds, a node
is able to dynamically adjust the contention window size and thus
improve performance.
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Oct-10-2006
11:00AM
121 CIS |
Speaker: Dr. Shengquan Wang
Topic: Temperature-Constrained Real-Time Systems
Abstract: As power density in processors has increased
exponentially in recent years, processors are prone to overheating
caused by the large energy consumption. Temperature is becoming one of
the big concerns in system design. Naturally, power management
plays a key role in maintaining temperature. However, the
majority of the literature focuses on power management for the
purpose of saving energy, not for maintaining safe temperature
levels. While energy and temperature are closely related, power
control mechanisms and temperature control mechanisms are quite
different. This is due to the fact that energy- aware techniques focus
on dealing with the average energy consumption while
temperature-aware ones focus on handling peak energy consumption.
I am interested in temperature-constrained real-time systems, which
have two major constraints: the delay constraint for jobs and the
temperature constraint for the processor. Dynamic speed scaling
is one of the major techniques for power management, which can
control the power in the processor by dynamically changing the
speed of the processor. Dynamic speed scaling allows for a trade-off
between the performance metrics of delay and temperature in
temperature- constrained real-time systems: to meet the delay
constraint, we run the processor at a higher speed; to maintain
the safe temperature levels, we run the process at a lower speed.
In this talk, I am going to present some preliminary results and
some potential research areas.
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Oct-17-2006
11:00AM
121 CIS |
Speakers: Dr. Jinhua Guo
Topics: Contexted Assisted Routing Procotols for Vehicular Ad hoc
Networks
Abstract: Due to the very high rate of topological changes and
frequent network partitions, routing in VANETs is a formidable
challenge. Previous studies in ad hoc networks mainly deal with
networks in which the topology changes are very slow. However,
the high mobility aspects of the nodes as in the case for VANETs are
not well studied. Furthermore, there have previously been few
studies on how the specific movement patterns of vehicles may influence
the protocol performance and applicability. In this paper, we
propose a Context Assisted Routing (CAR) protocol, which takes into
account various domain specific contexts while routing packets. A
source node exploits global context information such as road topology,
traffic information, and roadside access points, to compute the
forwarding trajectory, which efficiently bypasses the topology
holes. The intermediate nodes utilize local context information,
such as locations, velocities and driving directions of neighboring
vehicles to greedily forward the packets to nodes that lie on the
trajectory. Simulation results show that the proposed CAR
protocol outperforms the traditional geographic forwarding in terms of
packet delivery ratio and average delivery delay.
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Oct-24-2006
11:00AM
121 CIS |
Speaker: Dr. Zhen-Jun Shi
Topic: Several New Line Search Methods and Its Convergence
Abstract: In this report, we proposed several new line search
methods
for unconstrained minimization problems. The modified line search
rule used in the method makes the step-size have a wider scope
than the original line search rules do. It is clarified that the
new line search methods have global convergence under mild
conditions. It is also proved that the search direction plays an
important role in line search methods and that the step-size rule
mainly guarantees the global convergence in much more cases. The
convergence rate of these methods is also investigated. These
theoretical results can help us design some new effective
algorithms in practice.
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Oct-31-2006
11:00AM
121 CIS |
Speakers: Mr. John P. Baugh
Topics: Security and Privacy in VANETs using Group Signatures
Abstract: With the ever-increasing interest in mobile ad-hoc
networks (MANETs) and specifically in vehicular ad-hoc networks
(VANETs), there is much research and interest in the security and
privacy considerations that deal with these types of networks. In
this talk, I will describe the fundamental information regarding VANETs
and a privacy-preserving cryptographic paradigm known as group
signatures, and why this signature scheme may be appropriate for the
vehicular environment.
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Nov-16-2006
11:00AM
121 CIS |
Speaker: Dr. Bruce Elenbogen
Topic: Choosing Effective Multiple Leaky Buckets for Traffic Shaping of
VBR ATM traffic
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