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Oct13
EVENT DETAILS
lessTitle: Fast Direct Solvers for Boundary Integral Equations
Speaker: Adrianna Gillman, University of Colorado Boulder
Abstract: The numerical solution of linear boundary values problems play an important role in the modeling of physical phenomena.
As practitioners continue to want to solve more complicated problems, it is important to develop robust and efficient numerical methods. For some linear boundary value problems, it is possible to recast the problem as a boundary integral equation which sometimes leads to a reduction in dimensionality. The trade-off for the reduction in dimensionality is the need to solve a dense linear system. Inverting the dense N by N matrix via Gaussian elimination has a computational cost of O(N^3). When N is large, the cost in both memory and computational resources is too high for most practitioners. This talk presents solution techniques that exploit the physics in the boundary integral equation to invert the dense matrix for a cost that scales linearly (or nearly linearly) with N with
small constants. For example, on a laptop computer, a matrix with N=100,000 can be inverted in 90 seconds and applying the solver takes under a tenth of a second. The speed in which new boundary conditions can be processed makes these methods ideal applications involving many solves such as optimal design and inverse scattering. In these applications, fast direct solvers observe hundreds of times speed up over previously state of the art techniques. Examples of how these techniques can be used to create accelerated solvers for problems where the linear scaling solver is excessive will also be presented.
Bio: Adrianna Gillman is an Associate Professor in the Department of Mathematics at the University of Colorado, Boulder. In 2018, she was awarded an Alfred P. Sloan Research Fellowship. Her work has been supported by industrial contracts, NSF and, most recently, the Knut and Alice Wallenberg Foundation Grant, in cooperation with the Royal Swedish Academy of Sciences. Gillman’s research lies in the intersection of numerical linear algebra and numerical partial differential equations with an emphasis on developing high order discretizations and efficient solvers for the linear systems that result from these discretizations. Her work has been applied to applications including scattering and Stokes flow.
Zoom: https://northwestern.zoom.us/j/96310557268
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TIME Tuesday, October 13, 2026 at 11:00 AM - 12:00 PM
LOCATION M416, Technological Institute map it
CONTACT Natalie Masini natalie.masini@northwestern.edu EMAIL
CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)
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Oct19
EVENT DETAILS
lessTitle: Memory Formation in Particle Packings
Speaker: Dr. Sidney Nagel, University of Chicago
Abstract: A disordered solid created by packing spheres in a box has a myriad of stable configurations that defy straightforward enumeration and characterization. Since structure often determines function, each distinct arrangement potentially corresponds to different material behavior. The question naturally arises: How many mechanically stable ways are there to pack N identical spheres in a box? This has the spirit of a “Fermi estimation problem,” but one for which we do not have an answer: we do not know how to account for rearranging the particles to produce packings with different connectivity. We therefore resort to measurement.
Stable packings of N identical soft spheres in d dimensions lie at the minima of a vast (Nd)-dimensional potential energy landscape. Starting from random positions, the particles can relax to mechanical equilibrium; all initial conditions that end at the same minimum belong to the same catchment basin. We find a very wide distribution of basin volumes. These results suggest how to understand the imprinting of memories in solids.
Bio: Sidney Nagel was educated at Columbia University (B.A. in 1969) and at Princeton University (Ph.D. in 1975). He did a postdoc at Brown and then moved to the University of Chicago in 1976 where he has remained and is now the Stein-Freiler Distinguished Service Professor in the Department of Physics and the James Franck and Enrico Fermi Institutes. Nagel is a condensed-matter experimentalist focusing on problems where the physics of disorder and far-from-equilibrium behavior play crucial roles. Of particular delight is when table-top experiments have analogs in disparate fields at wildly different scales. In particular, he has studied the glass transition, the phenomenology of granular material, and the physics of jamming; he has also focused on pattern and singularity formation in fluid interfaces, and the formation of stains left behind by evaporating liquid drops. A current interest is the investigation of memory formation in out-of-equilibrium matter. He has worked to make his science accessible to a broad public by emphasizing the inherent beauty of the phenomena he studies in the laboratory.
Zoom: https://northwestern.zoom.us/j/98030602428
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TIME Monday, October 19, 2026 at 4:00 PM - 5:00 PM
LOCATION ITW (Room 1.350), Ford Motor Company Engineering Design Center map it
CONTACT Natalie Masini natalie.masini@northwestern.edu EMAIL
CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)
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Oct27
EVENT DETAILS
lessTitle: Advances in Asymptotic and Computational Methods for Biological Transport
Speaker: Alan Lindsay, University of Notre Dame
Abstract: Asymptotic analysis remains one of the most powerful analytical tools for extracting interpretable information from mathematical models in science. These methods systematically exploit multiscale structure to reduce complex and often intractable problems to a sequence of tractable sub-problems. When coupled with modern numerical methods, they greatly expand the range and scope of scientific questions that can be addressed.
In this talk I will discuss the insights these tools have yielded into the role that geometry, dynamics and localization play in biological transport. For the diffusive delivery of cargoes to small reactive sites, they give precise information on how the spatial organization of those sites shapes function. This has led to new solutions to the long-standing Berg-Purcell problem and the narrow escape problem. Underpinning these results is a suite of high-order boundary integral solvers which pair with asymptotic methods to resolve multiscale features and massively expand the geometric scope of biological problems that can be investigated. Throughout the talk I will highlight where interactions with experimental science have guided the direction of the mathematics, and I will close with promising directions for future enquiry.
Zoom: https://northwestern.zoom.us/j/98486002568
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TIME Tuesday, October 27, 2026 at 11:00 AM - 12:00 PM
LOCATION M416, Technological Institute map it
CONTACT Natalie Masini natalie.masini@northwestern.edu EMAIL
CALENDAR McCormick-Engineering Sciences and Applied Mathematics (ESAM)
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Dec12
EVENT DETAILSmore info
lessThe ceremony will take place on Saturday, December 12 in Pick-Staiger Concert Hall, 50 Arts Circle Drive.
TIME Saturday, December 12, 2026 at 4:00 PM - 6:00 PM
LOCATION Pick-Staiger Concert Hall map it
CONTACT Andi Joppie andi.joppie@northwestern.edu EMAIL
CALENDAR McCormick School of Engineering and Applied Science