This thesis investigates the impact of edge burr faults on total power loss in electrical machine core laminations. Analytical techniques, experimental work and FEM modelling have been utilised to investigate the effect of the phenomenon from different aspects. Measurements of overall specific total loss and analytical techniques were used to separate the power loss components over wide magnetising frequency ranges. Two techniques were used in this project for edge burr simulation; these include (1) the short circuiting of two Epstein-size and three Epstein-size and large-size, non-oriented steel laminations by lead-free solder in the rolling and transverse directions and (2) the by clamping system method, which was designed for the application of edge burrs on toroid cores. Various sizes of artificial edge burrs were applied at set points and then in a random manner to confirm their effect and show the extent of their effect in different case scenarios and the tests were completely repeatable. 3-D FEM modelling for toroid cores was also used to study the impact of core geometry on the total core loss. This method provided a clear explanation for why smaller toroid cores have higher power loss than the larger ones. The research presented in this thesis can be utilised by electrical steel manufacturers and electrical machine designers to evaluate the impact of edge burr faults on the properties of magnetic cores. The evaluation is beneficial because it could reduce the risk of local overheating of laminated magnetic material, which can lead to destruction of such an electrical machine.

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This thesis presents findings of hydrothermally synthesised barium titanate nanoparticles for biomarker applications. Hydrothermal barium titanate (H-BT) and barium strontium titanate (H-BST) nanoparticles were successfully synthesised and were characterised for their second harmonic generation applications. X-Ray powder diffraction (laboratory and synchrotron) highlighted that H-BT and H-BST had a mixed tetragonal and cubic phase fraction present by Rietveld peak fitting analysis. Regardless of the phase fractions present, all nanoparticles emitted SHG (including a commercial cubic BaTiO3 sample that appeared cubic by XRD). The smaller sized H-BST nanoparticles (45 nm) required an increase in incident laser power compared to the H-BT sample (~140 nm). The phase of the nanoparticles and origin of SHG was investigated by electron diffraction, electron energy loss spectroscopy and high resolution HAADF-STEM imaging. In-situ electron diffraction of barium titanate showed that the tetragonal diffraction pattern transformed to a cubic pattern when heated above the Curie point. The phase transition was also investigated by EELS measurements of the Ti-L3 edge t2g-eg peak separation at room temperature and 400 oC showing the reduction in t2g-eg peak separation when the sample transforms from a tetragonal to cubic phase. The surface of the nanoparticles also showed an atomically rough layer with incomplete unit cells, and the ‘bulk’ of the nanoparticles showed random Ti-atom distortions by HAADF-STEM Ti-atom displacement analysis. This suggests the origin of SHG is likely to be both a cause of surface roughness and local asymmetric distortions in the nanoparticle bulk. The hydrothermally prepared and PLL-coated nanoparticles were measured to assess the cell viability and DNA damage of cells after a 24-hour exposure. The nanoparticles were measured by dynamic light scattering to understand the behaviour of uncoated and PLL-coated nanoparticles suspended in different media. The uncoated nanoparticles showed little reduction in cell viability and genotoxicity, whereas the PLL coated nanoparticles showed a reduction in cell viability and a failed comet assay at concentrations ≥10 µg/mL. The nanoparticles were confirmed to be taken up into the cells by electron microscopy of critically point dried and resin embedded cell sections. Cryo-TEM of the H-BT-PLL nanoparticles suspended at 100 µg/mL in complete cell culture media showed that some nanoparticles were coated with a calcium phosphate coating and others not. This resulted in, either cells having a direct exposure to PLL and positively charged nanoparticles, or all the calcium was removed from the media that is required for cell signalling pathways which could lead to a reduction in cell viability.

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