Week of 26 October 2014 Mathematics Seminars



Wall to wall optimal transport

Tuesday, October 28, 2014 at 3:30p.m.
Charles R. Doering (Depts. of Physics, Mathematics and Center for Study of Complex Systems, University of Michigan, Ann Arbor)
Abstract: How much stuff can be transported by an incompressible flow containing a specified amount of kinetic energy or enstrophy? We study this problem for steady 2D flows focusing on passive tracer transport between two parallel impermeable walls, employing the calculus of variations to find divergence-free velocity field with a given intensity budget that maximize transport between the walls. The maximizing velocity fields, i.e. the optimal flows, consist of arrays of (convection like) cells. Results are reported in terms of the Nusselt number Nu, the convective enhancement of transport normalized by the flow-free diffusive transport, and the Péclet number Pe, the dimensionless gauge of the strength of the flow. For both energy and enstrophy constraints we find that as Pe increases, the maximum transport is achieved by cells of decreasing aspect ratio. For each of the two flow intensity constraints, we also consider buoyancy-driven flows the same constraint to see how the scalings for transport reported in the literature compare with the absolute upper bounds. This work provides new insight into both steady optimal transport and turbulent transport, an increasingly lively area of research in geophysical, astrophysical, and engineering fluid dynamics. This is joint work with Pedram Hassanzadeh (Berkeley/Harvard) and Gregory ...

Monday, 27 October 2014

Topology Seminar

The higher Morita category of E_n-algebras at 2:30p.m. in VinH 570
Rune Haugseng (Max-Planck Institute for Mathematics)
I will discuss a construction of a higher category of E_n-algebras and iterated bimodules, generalizing the classical bicategory of algebras and bimodules. This leads to ... (more)

Automorphic Forms and Number Theory

Examples: discrete spectra at 3:35p.m. in 206 Vincent Hall

Tuesday, 28 October 2014

Climate Seminar

Understanding early agricultural impacts on climate with dynamical systems at 11:15a.m. in VinH 570
Alice Nadeau (U of M Mathematics Department)

Combinatorics Study Group

Topics in Combinatorics Study Group at 1:25p.m. in VinH 203A


Wall to wall optimal transport at 3:30p.m. in VinH 16
Charles R. Doering (Depts. of Physics, Mathematics and Center for Study of Complex Systems, University of Michigan, Ann Arbor)
How much stuff can be transported by an incompressible flow containing a specified amount of kinetic energy or enstrophy? We study this problem for steady ... (more)

Geometric Analysis Learning Seminar

Definition of the center of mass -- stability and uniqueness at 3:30p.m. in VinH 206
Pak Yeung Chan (U of M Mathematics Department)

Wednesday, 29 October 2014

Student Stochastic Seminar

An Introduction to Noise Sensitivity at 2:00p.m. in VinH 570
Zach Hamaker (IMA)
We will introduce the concept of noise sensitivity and outline some of its connections to percolation. In doing so, we will use several tools from ... (more)

Algebraic Geometry

Virtual invariants on Quot schemes over del Pezzo surfaces at 2:30p.m. in Vincent Hall 313
Daniel Schultheis (U of M)
. The Quot scheme over a smooth projective curve C offers a compactification of the space of maps from C to a Grassmannian. Numerous mathematicians ... (more)

PDE Seminar

On the quasiconvergence property of solutions of reaction-diffusion equations on R at 3:35p.m. in VinH 206
Professor Peter Polacik (University of Minnesota)
We examine bounded solutions of semilinear parabolic equations on the real line. Such a solution u(.,t) is called quasiconvergent if it approaches a set of ... (more)

Thursday, 30 October 2014

Math Club Seminar

Ramsey Theory at 12:20p.m. in VinH 570
Christian Gaetz (University of Minnesota)
Ramsey’s Theorem states that if the edges of a sufficiently large complete graph are 2-colored, there will exist a complete monochromatic sub-graph of the desired ... (more)

Algebra Reading Seminar

Stability conditions in the sense of Bridgeland - a continuation at 1:00p.m. in Physics 133
Professor Peter Webb (U of M Mathematics Department)

Friday, 31 October 2014

Combinatorics Problem Session

All are welcome to pose a short combinatorics problem, or discuss problems posed by others at 2:30p.m. in VinH 570
to be announced

Probability Seminar

Asymptotic results for the longest common subsequence problem at 2:30p.m. in VinH 207
Umit Islak (U of M Mathematics Department)
Let (X_k)_{k \geq 1} and (Y_k)_{k\geq1} be two independent sequences of i.i.d. random variables having the same law and taking their values in a finite ... (more)

Lie Theory Seminar

The Langlands Classification at 3:30p.m. in VinH 209
Mr. Fangyang Tian (U of M)

Combinatorics Seminar

Toric arrangements -- towards setting up a combinatorial theory at 3:35p.m. in VinH 570
Emanuele Delucchi (University of Bremen)
Recent work of De Concini, Procesi and Vergne on vector partition functions gave a new impulse to the study of toric arrangements from an algebraic, ... (more)

MCFAM Seminar

Yield Curves and Eventual Total Positivity at 5:30p.m. in VinH 16
Dr. Carlos Tolmasky (Institute of Mathematics and Its Applications (IMA) - University of Minnesota)
Principal components analysis has become widely used in a variety of fields. In finance and, more specifically, in the theory of interest rate derivative modeling, ... (more)