Name: Dimitris Hristu
Email: hristu@arcadia.harvard.edu
Group: Division of Applied Sciences, Harvard
Title: Control with Limited Communication"
Statement: This work is an attempt to bring together in an elegant
manner, issues in control and communication. We consider a class of
continuous-time systems where inputs and outputs must be communicated
from and to a controller, over a bus of finite capacity. The
controller must typically spend some of its time performing
computations and the dimension of the bus may be less than that of
the input/output signals. Consequently, communication with the
control system occurs at discrete times and the controller must
choose which inputs/outputs to update/read at a particular time. This
leads to a theory of sampled-input continuous systems where
communication and control are naturally coupled. The theory allows us
to solve tracking and stabilization problems as well as to define and
represent ``attention'' in the context of control systems with
limited communication.
The theory has relevance in areas where system complexity is an
issue, as in the coordinated control of aerial vehicles (UAV's), MEMS
devices or any other setting where many systems must share the
attention of a decision--maker. In addition, it can be a promising
framework for posing questions related to optimal communication and
polling versus ``greedy'' communication policies.
Name: Christoforos Hadjicostis
Email: chadjic@allegro.mit.edu
Group: LEES/DSPG, M.I.T.
Title: Fault-Tolerant Monitoring of Discrete Event Systems using
Petri Net Embeddings (see Statement at the end of email)
Statement: Petri nets are a powerful graphical and mathematical model
for a variety of information and processing systems. In this talk, I
will present a methodology for monitoring failures and other activity
in discrete event systems that are described by Petri nets. The
method is based on embedding the given Petri net model into a larger
Petri net which retains the functionality and properties of the given
one, perhaps in a {\em non-separate} (that is, not immediately
identifiable) way. This {\em redundant Petri net embedding}
introduces ``structured redundancy'' which can be used to facilitate
fault detection, identification and correction, or to offer increased
capabilities for monitoring and control. I will focus primarily on
{\em separate embeddings} in which the functionality of the original
Petri net is retained in its exact form. Using these embeddings, I
will construct monitors that detect and identify different types of
failures by performing consistency checks between the state of the
original Petri net and that of the monitor. The methods that I
propose are attractive because the resulting monitors are robust to
failures, they may not require explicit acknowledgments from each
activity, and their construction is systematic and easily adaptable to
restrictions in the available information.
Name: Stark Draper
Email: scd@sllegro.mit.edu
Group: DSP, M.I.T.
Title: Multiple Source Descriptions via Lossy Lempel-Ziv
Statement: The objective of the multiple source descriptions
problem is to formulate a number of encodings of a
source such that each encoding meets a minimal
fidelity description on its own, but the more
descriptions received the higher fidelity can be
achieved. We think about approaching this problem
through a modification of the Lempel-Ziv algorithm.
----------------------------------------------------------------------
Name: Ilya Pollak
Email: ipollak@mit.edu
Group: SSG, MIT
Title: A Nonlinear Diffusion Equation as a Fast and Optimal Solver of
Edge Detection Problems.
Statement:
A nonlinear diffusion process known to be effective for image segmentation
is analyzed in 1-D. It is shown that it provides maximum likelihood solutions
for certain edge detection problems. This fact means that classical change
detection results can be used for performance analysis in some special cases.
The robustness of the algorithm is also analyzed using an H-infinity-like
criterion. The algorithm's connections with linear programming are explored.
A fast implementation of the algorithm is introduced.
---------------------------------------------------------------------------
Name: Chalee Asavathiratham
Email: chalee@mit.edu
Group: LEES, MIT
Title: Multidimensional Time-Frequency Uncertainty Principle
Statement:
The time-frequency uncertainty principle (UP) establishes the limit to
which a signal can be simultaneously concentrated both in the time and
frequency domain. The main result of this paper is the extension of
the UP to $m$-D signals by expressing the bound in the form of matrix
inequalities. By associating the covariance matrix of a given signal
to an ellipsoid of effective support, geometrically insightful
interpretations of the $m$-D UP can be made. The proof of the main
result is based on operator-theory, which allows us to easily derive a
similar set of inequalities for $m$-D discrete-time signals.
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Name: Nick Laneman
Email: jnl@allegro.mit.edu
Group: DSPG, MIT
Title: Temporal Diversity for Fading Channels
Statement:
Frequently, system designers employ an error-correcting code followed by
an interleaver to achieve temporal diversity over time-selective fading
channels. This talk will discuss efficient, rate-preserving alternatives
to coding plus interleaving that take the form of linear transformations
(blockwise or convolutional) of the input symbol sequence. These schemes
lend themselves to low-complexity decoding methods, such as linear
equalization followed by symbol-by-symbol detection. We are examining
the performance vs. complexity tradeoffs associated with several
suboptimal decoding techniques for these schemes, and exploring
combinations of these particular temporal diversity techniques with
linear spectral and spatial diversity techniques. We are also searching
for other, possibly nonlinear, transformations which offer significant
diversity benefit for similar computational cost.
-----------------------------------------------------------------------
Name: Michael Neely
Email: mjneely@mit.edu
Group: LIDS, MIT
Title: Queue occupancy in single server, deterministic service time
tree networks.
Statement:
Tree networks of single server, deterministic service time queues are
often used as models for packet flow in systems with ATM traffic. In
this tTitle: Universal Decoding
alk, we present a simple method of analyzing packet occupancy
in these systems without making any assumptions about the nature of the
underlying input processes. We demonstrate how analysis of multi-stage
tree systems can be reduced to the analysis of a much simpler 2-stage
equivalent model. We also develop an expression for first moments of
queue occupancy in terms of first moments of a simple 1-stage equivalent
model. From this, we observe an interesting phenomenon for general types
of "distributable inputs": Expected occupancy at any queue within a
multi-stage tree network will be a concave function of the loadings
produced by the multiple exogenous inputs.
----------------------------------------------------------------------
Name: Sridevi Sarma
Email: sree@mit.edu
Group: CSG, MIT
Title: Analysis of Cerebellar-Mediated Wave-Variable Servo Control System
Statement:
The peformance and stability of a cerebellar-mediated
wave-variable servo control system proposed by Steve Massaquoi will
be addressed. In addition, validity of model assumptions will be assessed.
----------------------------------------------------------------------
Name: Thierry Klein
Email: teklein@mit.edu
Group: LIDS, MIT
Title: Universal Power Control for Finite-State
Statement:
-----------------------------------------------------------------------
Name: Aaron Cohen
Email:
Group:
Title: Universal Decoding
Statement:
---------------------------------------------------------------------
Name: Babak Ayazifar
Email: babak@mit.edu
Group: LEES, MIT
Title:
Statement:
---------------------------------------------------------------------
Name: Anand Ganti
Email: aganti@mit.edu
Group: LIDS, MIT
Title: Mismatch Channel Capacity per Unit Cost
Statement:
The Mismatch Channel Capacity per Unit Cost represents the maximum
number of bits per unit cost that can be transmitted reliably across a
channel under conditions of mismatch. It's reciprocal gives the cheapest
cost of transmitting a bit reliably. We derive lower bounds for the Mismatch
Channel Capacity per Unit Cost as the cost tends to zero and discuss some of
its properties.
---------------------------------------------------------------------
Name: Jorge Goncalves
Email: jmg@mit.edu
Group: CSG, MIT
Title: Analysis of Relay Feedback Systems
Statement:
This paper presents sufficient stability conditions of limit
cycles for relay feedback systems. Local stability conditions exist. These
are based on analyzing the linear part of the Poincare map. We know that
when a certain limit cycle satisfies those local conditions, a neighborhood
around the limit cycle exists such that any trajectory starting in this
neighborhood converges to the limit cycle as time goes to infinity.
However, tools to characterize this neighborhood do not exist. In this
work, we present conditions, in the form of Linear Matrix Inequalities
(LMIs), that guarantee the stability of a limit cycle in a reasonably large
set around it. These results differ from previous local results as they
take into account the high order terms of the Poincare map.
--------------------------------------------------------------------
Name: Hisham Kassab
Email:
Group:
Title: Routing in Packet Radio Networks
Statement:
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Name: Andrew Kim
Email:
Group:
Title: Non-parametric Estimation of Anisotropic
Statement:
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?????????????????????????????
Name: Asuman Koksal
Email:
Group:
Title: Statistical Object Recognition
Statement:
------------------------------------------------------------------------
Name: Can Emre Koksal
Email:
Group:
Title: Communication Networks Theory
Statement:
------------------------------------------------------------------------
Name: Navid Sabbaghi
Email:
Group:
Title: Verification and Recognition
Statement:
-------------------------------------------------------------------------
Name: Paul Sotiriadis
Email:
Group:
Title: Asynchronous (Chaotic) Computations
Statement:
-----------------------------------------------------------------------
Name: Elif Uysal
Email: elif@mit.edu
Group: LIDS, MIT
TITLE: Maximizing Diversity in Slow Frequency Hopping
Statement:
This talk will address situations where channel memory is kept over a finite
block length. A motivating example is slow frequency hopping in wireless
communication, in particular, SFH/TDMA which is related with the GSM
standard. For a TDMA based scheme, a way of achieving additional diversity by
exploiting discontinuous transmission (such as voice activity) will be shown.
The operation of diversity in general will be observed, and limits on the
achievable diversity in general block-fading (or block-interference)
channels will be discussed.
------------------------------------------------------------------------
Name: Sean Warnick
Email: warnick@mit.edu
Group: CSG, MIT
Title: Piloting Epitaxy Through Ellipsometric Feedback
Statement:
Epitaxial processes are methods of systematically depositing specified
materials on a substrate. These processes are critical in the
production of various semiconductor devices, especially compound
semiconductor devices such as vertical cavity surface emitting lasers
(VCSELs) and other optical or optoelectronic devices.
The primary challenge for epitaxy is to realize a desired structure.
That is, we want to grow films such that the index of refraction, or
material composition, of the resulting device satisfies a desired
function of thickness. Recent advances in in-situ sensor
technology have made feedback available as a tool to address this
problem.
This study investigates the issues of designing controllers for
gas-source molecular beam epitaxy using spectroscopic ellipsometry as
a sensor technology.
------------------------------------------------------------------------
Name: Richard Barron
Email:
Group: DSPG, MIT
Title:
Abstract:
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Name: Maurice Chu
Title: Learning and Vision
Email:
Group:
Statement:
--------------------
Name: Sae-Young Chung
Title: Coding Theory
Email:
Group:
Statement:
----------------------
Name: Angelia Geary
Title: Nonlinear Optimization
Email:
Group:
Statement:
-------------------------
Name: John Richards
Email:
Group:
Title: Target Model Generation for Multiple SAR Images
Statement:
----------------------------------
Name: Tengo Saengudomlert
Email:
Group:
Title: Networks
Statement:
--------------------------------
Name: Anant Sahai
Email:
Group:
Title: Information Theory and Control
Statement:
--------------------------