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Mar17
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lessWinter exams begin
TIME Monday, March 17, 2025
CONTACT Office of the Registrar nu-registrar@northwestern.edu EMAIL
CALENDAR University Academic Calendar
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Mar22
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lessSpring Break Begins
TIME Saturday, March 22, 2025
CONTACT Office of the Registrar nu-registrar@northwestern.edu EMAIL
CALENDAR University Academic Calendar
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Mar31
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lessSpring Break Ends
TIME Monday, March 31, 2025
CONTACT Office of the Registrar nu-registrar@northwestern.edu EMAIL
CALENDAR University Academic Calendar
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Apr1
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lessSpring Classes Begin - Northwestern Monday: Classes scheduled to meet on Mondays meet on this day.
TIME Tuesday, April 1, 2025
CONTACT Office of the Registrar nu-registrar@northwestern.edu EMAIL
CALENDAR University Academic Calendar
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Apr1
EVENT DETAILS
lessTitle: Two Tales, One Resolution: Physics-Informed Test Time Scaling and Precondition
Speaker: Yiping Lu, Northwestern University
Abstract: In this talk, I will introduce a novel framework for physics-informed debiasing of machine learning estimators, which we call Simulation-Calibrated Scientific Machine Learning (SCaSML). This approach leverages the structure of physical models to achieve two key objectives:
Unbiased Predictions: It produces unbiased predictions even when the underlying machine learning predictor is biased.
Overcoming Dimensionality Challenges: It mitigates the curse of dimensionality that often affects high-dimensional estimators.The SCaSML paradigm integrates a (potentially) biased machine learning algorithm with a de-biasing procedure that is rigorously designed using numerical analysis and stochastic simulation. Our methodology aligns with recent advances in inference-time computation—similar to those seen in the large language model literature—demonstrating that additional computation can enhance ML estimates. Furthermore, we establish a surprising equivalence between our framework and another research direction that utilizes approximate (linearized) solvers to precondition iterative methods. This connection not only bridges two distinct areas of study but also offers new insights into improving estimation accuracy in complex, high-dimensional (PDE) settings.
Zoom: https://northwestern.zoom.us/j/94570889326
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TIME Tuesday, April 1, 2025 at 11:15 AM - 12:15 PM
LOCATION M416, Technological Institute map it
CONTACT Ted Shaeffer ted.shaeffer@northwestern.edu EMAIL
CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)
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Apr15
EVENT DETAILS
lessTitle: Phase-Amplitude-Based Techniques for Control and Analysis of Strongly Perturbed Limit Cycle Oscillators
Speaker: Dan Wilson, University of Tennessee, Knoxville
Abstract: While phase-based reduction techniques have a rich history in the analysis and control of oscillatory dynamical systems, the overwhelming majority of theoretical analysis in this field has been performed in the weakly perturbed limit. Comparatively very little is understood about limit cycle oscillators in response to strong and/or long-lasting perturbations, mostly due to the lack of viable reduction strategies that are valid when considering strong perturbations. In this presentation, I will discuss the use of isostable coordinates, which characterize level sets of the slowest decaying eigenmodes of the Koopman operator in conjunction with phase-based techniques to yield analytically tractable reduced order models that are valid in the strongly perturbed regime. Applications involving phase resetting of circadian rhythms following rapid travel across multiple time zones illustrate the utility of these new methods in situations where standard, phase-only techniques fail. I will also discuss related work motivated by experimental and detailed computational studies finding that coupled circadian oscillators with decreased levels of synchronization are able to more rapidly adjust to changes in circadian time. Theoretical analysis reveals the dynamics of mean-field coupled oscillators can be considered in the context of a supercritical Hopf bifurcation, ultimately providing an explanation for the fundamental relationship between synchronization and phase resetting efficiency. In the context of jet-lag recovery strategies, further analysis reveals that transient desynchronization facilitates phase resetting when the relaxation rate of the population limit cycle is sufficiently slow relative to the natural frequency of the population oscillation.
Zoom: https://northwestern.zoom.us/j/91324444590
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To subscribe to the Applied Mathematics Colloquia List send a message to LISTSERV@LISTSERV.IT.NORTHWESTERN.EDU with the command:
add esam-seminar Youremail Firstname Lastname
TIME Tuesday, April 15, 2025 at 11:15 AM - 12:15 PM
LOCATION M416, Technological Institute map it
CONTACT Ted Shaeffer ted.shaeffer@northwestern.edu EMAIL
CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)