3D shape based reconstruction of experimental data in Diffuse Optical Tomography

Diffuse optical tomography (DOT) aims at recovering three-dimensional images of absorption and scattering parameters inside diffusive body based on small number of transmission measurements at the boundary of the body. This image reconstruction problem is known to be an ill-posed inverse problem, which requires use of prior information for successful reconstruction. We present a shape based method for DOT, where we assume a priori that the unknown body consist of disjoint subdomains with different optical properties. We utilize spherical harmonics expansion to parameterize the reconstruction problem with respect to the subdomain boundaries, and introduce a finite element (FEM) based algorithm that uses a novel 3D mesh subdivision technique to describe the mapping from spherical harmonics coefficients to the 3D absorption and scattering distributions inside a unstructured volumetric FEM mesh. We evaluate the shape based method by reconstructing experimental DOT data, from a cylindrical phantom with one inclusion with high absorption and one with high scattering. The reconstruction was monitored, and we found a 87% reduction in the Hausdorff measure between targets and reconstructed inclusions, 96% success in recovering the location of the centers of the inclusions and 87% success in average in the recovery for the volumes

A comparison of the use of traditional glazing and a novel concentrated photovoltaic glazing (CoPVG) for building solar gain analysis using IESVE

The aim of this study is to compare the difference in solar gain for an internal space when a novel Concentrated Photovoltaic Glazing (CoPVG) unit is compared against traditional glazing modules. The CoPVG is an innovative glazing system developed by Ulster University, that takes advantage of Total Internal Reflection (TIR) to direct solar radiation into the internal space during periods of low solar altitude (around winter) harnessing the thermal contribution of solar gain and daylight. During periods of higher solar altitude (around summer), the solar radiation is mostly directed onto embedded photovoltaic cells. Previous work assessed the concept’s optical functionality, through experimental measurement and computational ray-tracing. Dynamic simulation in Matrix Laboratory (MATLAB) using a series of codes to represent the optical function of the CoPVG’s and Integrated Environmental Solutions Virtual Environment (IESVE) was validated by the experimental data. This work investigates methodologies in determining the transmissivty of the system in a dynamic simulation approach using ray tracing and Radiance in IESVE for visualisation, thereby building on the versability of this software to allow building designers and consultants to investigate energy and economic benefits of this system and systems like it in real building applications. The impact of integrating CoPVG as a replacement to traditonal glazing on a sun-facing building facade is assessed and the solar gain in the adjaciant space is compared throughout the year. During the summer months the integrated system reduces solar gain in the space by 34% but only 11% in the winter months, representing a reduction in the overall annual building energy needs. The study presents the potential economic and environmental savings provided by reduced cooling.<br/