Fall 2018 Seminars

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CSCAMM Faculty and Staff Meeting

Sep. 12, 2:00 pm
Professor Dionisios Margetis, CSCAMM, Mathematics & IPST, University of Maryland
Maxwell's equations on 2D materials: A flavor of scattering, dispersion and homogenization on the flatland

The last decade has witnessed tremendous advances in the fabrication of two-dimensional (2D) materials
with novel electronic structures. Celebrated examples of such materials include graphene and black phosphorus.
The surface conductivity in these systems in the infrared frequency regime permits the propagation of fine-scale electromagnetic waves called surface plasmon-polaritons (SPPs).
In this talk, I will discuss macroscopic consequences of the optical conductivity of 2D materials via solutions of classical Maxwell's equations. I will formally discuss the following topics:
(I) Edges of anisotropic 2D materials act as induced sources of SPPs.
(II) Periodic structures made of 2D materials intercalated in conventional dielectrics may allow for the propagation
of homogenized, slowly varying waves with nearly no phase delay (epsilon-near-zero behavior).
(III) The curvature of 2D materials may generate further confinement of SPPs.
(IV) Nonlinearities of the 2D material and the ambient media cause non-intuitive dispersion of SPPs.
Part of this work is jointly with: A. Andreeva (U. Minnesota), E. Kaxiras (Harvard), T. Low (U Minnesota), M. Luskin (U. Minnesota), M. Maier (Texas A&M), A. Mellet (U MD)

Sep. 19, 2:00 pm
Prof. Weizhu Bao, Center for Computational Science & Engineering, National University of Singapore
Title TBA
Sep. 26, 2:00 pm
Prof. Antony Jose, Dept. of Cell Biology & Molecular Genetics, University of Maryland
Title TBA
Oct. 3, 2:00 pm
Speaker TBA,
Title TBA
Oct. 10, 2:00 pm
Prof. Pierre Gremaud, Department of Mathematics, North Carolina State University
Title TBA
Oct. 17, 2:00 pm
Prof. Pierre Germain, Courant Institute of Mathematical Sciences, New-York University
Title TBA
Oct. 24

KI-Net Conference

Oct. 31, 2:00 pm
Prof. Daniele Boffi, Department of Mathematics, The University of Pavia
A fictitious domain approach for fluid-structure interaction problems
We discuss a distributed Lagrange multiplier formulation of the Finite Element Immersed Boundary Method for the numerical approximation of the interaction between fluids and solids. The discretization of the problem leads to a mixed problem for which a rigorous stability analysis is provided. Optimal convergence estimates are proved for the finite element space discretization. The model, originally introduced for the coupling of incompressible fluids and solids, can be extended to include the simulation of compressible structures.
Nov. 7, 2:00 pm
Mr. James Scott, Department of Mathematics, The University of Tennessee Knoxville
A Fractional Korn-Type Inequality with Applications to Peridynamics
We show that a class of spaces of vector fields whose semi-norms involve the magnitude of “directional” difference quotients is in fact equivalent to the class of fractional Sobolev spaces. The equivalence can be considered a Korn-type characterization of fractional Sobolev spaces. We use the result to better understand the energy space associated to a strongly coupled system of nonlocal equations related to a nonlocal continuum model via peridynamics. Moreover, the equivalence permits us to apply classical Sobolev embeddings in the process of proving that weak solutions to the nonlocal system enjoy both improved differentiability and improved integrability.
Nov. 14, 2:00 pm
Dr. M. Paul Laiu, Computational and Applied Mathematics Group, Oak Ridge National Laboratory
A Positive Asymptotic Preserving Scheme for Linear Kinetic Transport Equations
We present a positive and asymptotic preserving numerical scheme for solving linear kinetic, transport equations that relax to a diffusive equation in the limit of infinite scattering. The proposed scheme is developed using a standard spectral angular discretization and a classical micro-macro decomposition. The three main ingredients are a semi-implicit temporal discretization, a dedicated finite difference spatial discretization, and realizability limiters in the angular discretization. Under mild assumptions, the scheme becomes a consistent numerical discretization for the limiting diffusion equation when the scattering cross-section tends to infinity. The scheme also preserves positivity of the particle concentration on the space-time mesh and therefore fixes a common defect of spectral angular discretizations. The scheme is tested on well-known benchmark problems with a uniform material medium as well as a medium composed from different materials that are arranged in a checkerboard pattern.
Nov. 21
No seminar. Thanksgiving.
Nov. 28, 2:00 pm
Speaker TBA,
Title TBA
Dec. 5, 2:00 pm
Prof. Edinah Gnang, Department of Applied Mathematics and Statistics, Johns Hopkins University
Title TBA

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