News & EventsDepartment Events
Events
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Apr9
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Title: Tales of tails: Elastohydrodynamics of microscale motion
Speaker: Maciej Lisicki, University of Warsaw and UPenn
Abstract: A look into the microworld reveals plethora of swimming microorganisms, which display a rich variety of shapes and swimming gaits. Despite this diversity, physics of microscale imposes universal limitations on their propulsion strategies. In my talk, I will review the basic properties of Stokes flows and their consequences on swimming. Next, I will show an artificial system of microscale oil droplets that have the ability to swim due to a surface phase transition driven by environmental temperature fluctuations. I will demonstrate how a coarse-grained elastohydrodynamic model can be successfully employed to quantitatively describe the motion of droplets. I will also show a couple of other examples where a simplified elastohydrodynamic model proves useful for the prediction of diffusive properties.
Zoom: https://northwestern.zoom.us/j/95467525146
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TIME Tuesday, April 9, 2024 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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Mar31
EVENT DETAILS
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
EVENT DETAILS
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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Apr8
EVENT DETAILS
lessTitle: The Countoscope: Counting Particles to Measure Dynamic Properties of Suspensions In and Out of Equilibrium
Speaker: Brennan Sprinkle, Colorado School of Mines
Abstract: Modern microscopy techniques can image complex, microscopic systems with an unprecedented resolution – but methods to analyze these images are much less robust. Available techniques to probe dynamics rely on reconstructing particle trajectories, which can be difficult or impossible in some cases, or some form of video analysis, which can be unreliable and expensive. Inspired by the early work of Smoluchowski we introduce the `Countoscope’, a technique that near completely ameliorates these issues by simply counting particle number fluctuations in observation boxes. By varying properties like the size or aspect ratio of the boxes and taking different measures of correlation between these observation boxes, we can `zoom’ in or out to measure individual or collective particle kinetics in both passive and active systems. Using colloidal suspensions as a test case, we employ a combination of experiments, simulations, and analytical theory to support our findings.
Zoom: https://northwestern.zoom.us/j/97359869177
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TIME Tuesday, April 8, 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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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)
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Apr22
EVENT DETAILS
lessTitle: Control for Embodied Learning
Speaker: Todd Murphey, Northwestern University
Abstract: Embodied learning systems rely on motion synthesis to enable efficient and flexible learning during continuous online deployment. Motion motivated by learning needs can be found throughout natural systems, yet there is surprisingly little known about synthesizing motion to support learning for robotic systems. Moreover, robotic systems will need to collect data autonomously for learning, for instance when isolated for long period of time or when encountering novel environmental features. Learning goals create a distinct set of control-oriented challenges, including how to choose measures as objectives, synthesize real-time control based on these objectives, impose physics-oriented constraints on learning, and produce analyses that certify performance and safety with limited knowledge. This talk will discuss learning tasks that robots encounter, abstractions that enable regulating information content of observations, and recent progress on algorithms for generating action plans that facilitate learning.
Zoom: https://northwestern.zoom.us/j/96919208870
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TIME Tuesday, April 22, 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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May6
EVENT DETAILS
lessTitle: TBA
Speaker: Chris Vogl, Lawrence Livermore National Laboratory
Abstract: TBA
Zoom: TBA
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add esam-seminar Youremail Firstname Lastname
TIME Tuesday, May 6, 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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May27
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, May 27, 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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Jun15
TIME Sunday, June 15, 2025
CONTACT Office of the Registrar nu-registrar@northwestern.edu EMAIL
CALENDAR University Academic Calendar