
Mon 25 May 2015, 11:30am
SPECIAL
One Time Event
MATH 126

Mathematics Grad Reception

MATH 126
Mon 25 May 2015, 11:30am1:00pm
Details
The luncheon and awards presentation will be followed by the Niven Lecture at 1:15pm.
hide

Duke University

Mon 25 May 2015, 1:15pm
SPECIAL
Department Colloquium
MATX 1100

Niven lecture: Surfing with wavelets

MATX 1100
Mon 25 May 2015, 1:15pm2:15pm
Abstract
Wavelets provide a mathematical tool that emerged in the 1980s from a synthesis of ideas in mathematics, physics, computer science and engineering. They are now used in a wide range of mathematical applications, and provide a mathematical way to "zoom in" on details, without losing track of the large picture. The talk will describe some of the essential features of the approach, and illustrate with examples.
hide

PhD Candidate: Iain R. Moyles
Mathematics, UBC

Wed 27 May 2015, 12:30pm
SPECIAL
One Time Event
Room 203 of the Graduate Student Centre, 6371 Crescent Rd., UBC

Exam: Hybrid AsymptoticNumerical Analysis of Pattern Formation Problems

Room 203 of the Graduate Student Centre, 6371 Crescent Rd., UBC
Wed 27 May 2015, 12:30pm2:30pm
Details
ABSTRACT: We present an analysis of the GiererMeinhardt model with saturation (GMS) on various curve geometries in twodimensions. We derive a boundary fitted coordinate framework which translates an asymptotic twocomponent differential equation into a single component reaction diffusion equation with singular interface conditions. We create a numerical method that generalizes the solution of such a system to arbitrary twodimensional curves and show how it extends to other models with singularity properties that are related to the Laplace operator. This numerical method is based on integrating logarithmic singularities which we handle by the method of product integration where logarithmic singularities are handled analytically with numerically interpolated densities.
In parallel with the numerical method, we present some analytical solutions to the GMS model on circular and slightly perturbed circular curve geometries. We see that for the regular circle, saturation leads to a hysteresis effect for two dynamically stable branches of equilibrium radii. For the near circle, we show that there are two distinct perturbations to the velocity profile, one which introduces angular dependence, and one which introduces a vertical shift caused by quadratic Fourier mode interactions. We perform a linear stability analysis to the true circle solution and show that there are two classes of eigenvalues leading to breakup or zigzag instabilities. For the breakup instabilities we show that the saturation parameter can completely stabilize perturbations that we show are always unstable without saturation and for the zigzag instabilities we show that the eigenvalues are given by the nearcircle curve normal velocity. The breakup analysis is based on the reduction of an implicit nonlocal eigenvalue problem (NLEP) to a root finding problem. We derive conditions for which this eigenvalue problem can be made explicit and use it to analyze a stripe and ring geometry. This formulation allows us to classify certain technical properties of NLEPs such as instability bands and a Hopf bifurcation condition analytically.
The results for breakup and zigzag instabilities are verified with numerical simulations of the full model in both stripe and ring geometries. This includes confirmation of dominant breakup modes and demonstrating the stabilizing effect of saturation.
hide

UBC

Thu 28 May 2015, 2:00pm
Symmetries and Differential Equations Seminar
Math125

Direct construction of conservation laws and connections between symmetries and CLs. Part I

Math125
Thu 28 May 2015, 2:00pm3:00pm
Abstract
In this first lecture on the construction of the conservation laws for a DE system, we present the Direct Method. This leads to the direct construction of the CLs for essentially any DE system in a systematic framework. The classical Noether's Theorem only works for variational systems and also requires the construction of the Lagrangian. The Direct Method involves working directly with a given DE system. The second lecture will show explicitly how the Direct Method generalizes Noether's Theorem and overcomes all of its limitations.
hide

Seminar Information Pages

Note for Attendees
There will be the Grad Reception on Monday, May 25th at 11:301:00 (lunch and awards presentation).