<p>Thermophotovoltaic (TPV) systems have the potential to convert energy in a very efficient way by using 2D photonic crystal (PhC) emitters. Recent advancements in TPV technology have developed many methods for effectively generating power. These recent advancements propose that emitters can suppress low energy photon emissions while increasing higher energy photon emissions. This can be achieved by utilising new 2D photonic crystal (PhC) structures on the surface of the emitter with varying diameter and shape.</p><p>In this meta study we consider the multiple design fabrications of photonic crystal emitters and compare the efficiencies, power densities, and their potential use for converting different wavelengths into heat and power. This is done by analysing the thermodynamic factors present in the system that could potentially reduce the efficiency, and therefore power generation, of the thermophotovoltaic cell. This study found that certain shapes and materials can impact on the PhC structure and its ability to emit energy. </p>

The objectives of the present study were to describe the approach used for classifying surface tissue, and for estimating fat depth in lamb short loins and validating the approach. Fat versus non-fat pixels were classified and then used to estimate the fat depth for each pixel in the hyperspectral image. Estimated reflectance, instead of image intensity or radiance, was used as the input feature for classification. The relationship between reflectance and the fat/non-fat classification label was learnt using support vector machines. Gaussian processes were used to learn regression for fat depth as a function of reflectance. Data to train and test the machine learning algorithms was collected by scanning 16 short loins. The near-infrared hyperspectral camera captured lines of data of the side of the short loin (i.e. with the subcutaneous fat facing the camera). Advanced single-lens reflex camera took photos of the same cuts from above, such that a ground truth of fat depth could be semi-automatically extracted and associated with the hyperspectral data. A subset of the data was used to train the machine learning model, and to test it. The results of classifying pixels as either fat or non-fat achieved a 96% accuracy. Fat depths of up to 12 mm were estimated, with an R2 of 0.59, a mean absolute bias of 1.72 mm and root mean square error of 2.34 mm. The techniques developed and validated in the present study will be used to estimate fat coverage to predict total fat, and, subsequently, lean meat yield in the carcass.