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Thursday, September 28, 2017
2:00 PM - 3:00 PM
CNLS Conference Room (TA-3, Bldg 1690)

Seminar

Path optimization with application to particle tunneling, seismic wave propagation and radio wave tracing in the ionosphere

Hannes Jonsson
University of Iceland

A method will be presented for finding an optimal path in the sense of a line integral, i.e. an objective function that involves an integral along a path. The calculation starts with a discrete representation of an initial path, a sequence of values for the relevant variables. Then, an iterative algorithm is used to advance the discretization points to an optimal path, a path for which the derivatives of the objective function perpendicular to the path are zero. The boundary conditions on the endpoints can be some specified values of the variables or of the integrand. An important aspect of the method is an estimation of the tangent to the path at each discretization point and elimination of the component of the gradient of the objective function in the direction of the path during the iterative optimization. The method is a generalization of the nudged elastic band method for finding minimum energy paths. A few applications will be discussed: (1) tunneling paths for particles in a system with a given energy or a given temperature, (2) path of shortest travel time for a seismic wave between two locations, and (3) paths for radio waves in the ionosphere.

Host: Angel Garcia