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Department
of Mathematics, WUSTL - Talks List, Spring 2009
A list of lectures, seminars, colloquia, and other events hosted by
the Department of Mathematics at Washington University in St. Louis
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MAY 2009
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Friday, May 1
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Wavelet Seminar
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Time: 3:30-4:30pm
Location: Cupples I, Room 199
Host: Prof. Guido Weiss
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Speaker: Professor Guido Weiss
Department of Mathematics, Washington University in St. Louis
Title: Locally compact Abelian Groups and the Action of the Zac Transform
Abstract: This third lecture will extend the material of the previous lectures to the setting of Locally Compact Abelian groups.
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Monday, May 18
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Minor Oral
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Time: 3:00-4:00pm
Location: Cupples I, Room 199
Host: Prof. Al Baernstein
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Speaker: Jeffrey Langford
Department of Mathematics, Washington University in St. Louis
Title: The Isomorphism Problem from Ergodic Theory
Abstract: A classical problem in Ergodic theory is determining
whether two measure preserving transformations are isomorphic or not
(or conjugate or not). In order to solve this problem, one often
searches for invariants that remain unchanged under isomorphism. We
discuss the notions of isomorphism, conjugacy, and spectral
isomorphism and focus on several important examples to illustrate the
main ideas and shortcomings of certain invariants.
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Tuesday, May 26
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Wavelet Seminar
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Time: 3:30-4:30pm
Location: Cupples I, Room 199
Host: Prof. Guido Weiss
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Speaker: Professor Azita Mayeli
Department of Mathematics, Stony Brook University
Title: Shannon-type wavelet on the Heisenberg group
Abstract: Multiresolution Analysis (MRA) is a mathematical tool for the
construction of orthonormal wavelet bases for $L^2(\RR^n)$.
Motivated by MRA in the Euclidean setting, in this talk I will
present a notion and then a concrete example of a multiresolution analysis
on the Heisenberg group $\HH$. For our example, in contrast to the usual
approach on $\RR^n$, we start with construction of a sinc-type function
using the group Fourier transform. As we will discuss, the sinc-type
function implies the existence of a scaling function and hence a
normalized tight wavelet frame for $L^2(\HH)$. We call the generator of
this frame a Shannon-type wavelet on $\HH$.
Work in collaboration with Professor Currey, St. Louis University.
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JUNE 2009
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Tuesday, June 9
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Colloquium
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Time: Tea: 4:00-4:30pm
Talk: 4:30-5:30pm
Location: Cupples I, Room 199
Host: Prof. Victor Wickerhauser
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Speaker: Professor Peter F. Odgaard
KK Electronic A/S, Denmark
Title: Mathematically Model Based Control of Modern Wind Turbines
- from an Industrial Point of View
Abstract:
Newly installed wind turbines of today are normally in the multi-megawatt
range, with a blade diameter in the range from 80m to 110m. Consequently
optimization of these turbines is of high interest, for a number of reasons
and with different objectives. Some examples are: optimization of power
production, minimization of cost price per energy unit, lifetime expansion,
power quality, and reliability optimization. A model-based control strategy
is an important path to take in achievement of these different objectives.
This talk will start with a short presentation of modern wind turbines and
their control systems. The attention will subsequently be turned on to
specific problems recently suggested solved by model based schemes. An
adaptive scheme is suggested to adjust the power control to the wind turbine
operational point to the actual aerodynamics of the wind turbine blades. The
blade aerodynamics changes slowly with time mainly due to debris build-up on
the blades. An unknown input observer is designed based on a model of the
wind turbine to estimate the variation in actually aerodynamics compared
with
the assumed one. Based on this estimate, the aerodynamic model can be
updated with an interval of a month. The optimal point of operation of the
wind turbine can subsequently be found based on this updated model.
Fault detection and fault accommodation is at present handled in a simple
and
conservative way. Faults are directly detected based on the measurements,
and are most often handled by a shutdown of the turbine and an unplanned
service. This is costly both in lost production and the service itself,
increasing the cost price per energy unit and lowering the reliability of
the
wind turbine. If model based methods are used, faults can be detected either
faster or with less false positive detections. Secondly models can be used
to design analytical redundancy such that the turbine can continue
production
at some level in a safe way. Some recently published results in detection of
speed sensor faults and generator torque measurements are presented. In
order
to encourage the work on fault detection and accommodation on wind turbines,
a benchmark model of this problem has been developed and will be introduced.
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AUGUST 2009
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Tuesday, August 4
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Thesis Defense
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Time: 10:00-12:00pm
Location: Cupples I, Room 199
Host: Profs. Guido Weiss and Edward Wilson
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Speaker: Bob Houska
Department of Mathematics, Washington University in St. Louis
Title: Frames, Composite Wavelets, and Shearlets
Abstract: One-dimensional wavelet systems have enjoyed a great deal of
success in
applications. This success is due, in large part, to the plentiful
existence of compactly supported and smooth one-dimensional scaling
functions.
Traditional wavelet systems have been used quite successfully in
higher-dimensional applications as well. However, the geometric structure
present in dimensions two and higher is significantly more complex than
that present in dimension one, and there are several important
multi-dimensional applications for which traditional wavelet systems are
too geometrically simplistic. In response to this deficiency, the more
geometrically diverse composite wavelet systems were recently introduced
by Guo, Labate, Weiss, and Wilson.
A particular type of composite wavelet system - the shearlet system - has
been shown by the above mentioned authors to outperform traditional
wavelet systems in several important multi-dimensional applications.
Despite these positive results, however, shearlet systems have one major
drawback - essentially no useful shearlet scaling functions exist. We will
discuss several results of this variety.
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SPRING 2010 Seminars Schedule
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Thursday, April 22, 2010
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Loeb Lecture
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Time: Tea: 4:00-4:30pm
Talk: 4:30-5:30pm
Location: TBA
Host: Prof. Ronald Freiwald
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Speaker: Professor Martin Golubitsky
Department of Mathematics, Ohio State University
Title: TBA
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list?
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Last Updated 06/11/09
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