Tomographic reconstruction of stratified fluid flow

Flow visualization with stereo shadowgraphs of stratified fluid.

Water stratified thermally or with dissolved material has a refractive index that varies with height. The stratification has no obvious visual effect until the fluid is disturbed, for example by a fish, but then it marks the creature's wake with a jump in refractive index that is visible in shadowgraphic projection. Two shadowgraphs in stereo display the wake in three dimensions. For a permanen...

Linear Inviscid Damping for Couette Flow in Stratified Fluid

We study the inviscid damping of Couette flow with an exponentially stratified density. The optimal decay rates of the velocity field and the density are obtained for general perturbations with minimal regularity. For Boussinesq approximation model, the decay rates we get are consistent with the previous results in the literature. We also study the decay rates for the full Euler equations of st...

Tomographic Image Reconstruction

Binary tomographic reconstruction

The binary tomographic reconstruction problem consists of finding a binary image from (very) few projections (line sum of pixels) along given directions [1]. An efficient heuristic algorithm is introduced [2]. The first (initialization) step is similar to the traditional “filtered backprojection” algorithm used for standard tomographic reconstructions, but based on a non-linear transform, s = ...

Parallelisation of Tomographic Reconstruction Methods

In medicine, there is a still growing interest in non-invasive examination techniques which can depict anatomical structures. Amongst these methods are Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET) and Computerised Tomography (CT). These are all based on the same principle: under a number of angles, a set of line integrals in a plane is measured resulting in a set of proo...