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This thesis presents the development of a variety of discontinuous isogeometric discretisations of the discrete ordinates equations for neutron transport in two spatial dimensions. Three discretisations are presented of increasing sophistication, and their convergence properties analysed for a wide selection of test cases. The first discretisation uses a conforming mesh approach, which is analogous to many existing discontinuous Galerkin finite element methods for the discrete ordinates equations. This simplifies the analysis of the differences between isogeometric and finite element methods in terms of the numerical upwinding and sweep ordering. The second discretisation extends this approach by introducing hanging-nodes into the mesh. This overcomes the limitation of the tensor-product refinement structure inherent to isogeometric analysis based on non-uniform rational B-splines with a conforming mesh. Adaptive mesh refinement based on element subdivision is also introduced at this point, driven by a selection of heuristic error indicators. In the final discretisation, each energy group has its own associated mesh. The interpolation of functions between meshes is greatly simplified by deriving the mesh in each energy group from a common initial coarsest mesh. To take full advantage of the flexibility of this discretisation, dual weighted residual error metrics are derived for the multigroup discrete ordinates equations for both fixed source and eigenvalue problems. In a representative deep penetration shielding problem, this method is demonstrated to achieve the same level of accuracy in a detector response as uniform, conforming mesh refinement using approximately an order of magnitude less computational effort.

This thesis is concerned with maximising the precision of permanently installed ultrasonic time of flight sensors. Numerous sources of uncertainty affecting the measurement precision were considered and a measurement protocol was suggested to minimise variability. The repeatability that can be achieved with the described measurement protocol was verified in simulations and in laboratory corrosion experiments as well as various other experiments. One of the most significant and complex problems affecting the precision, inner wall surface roughness, was also investigated and a signal processing method was proposed to improve the accuracy of estimated wall thickness loss rates by an order of magnitude compared to standard methods. It was found that the error associated with temperature effects is the most significant among typical experimental sources of uncertainty (e.g. coherent noise and coupling stability). By implementing temperature compensation, it was shown in laboratory experiments that wall thickness can be estimated with a standard deviation of less than 20 nm when temperature is stable (within 0.1 C) using the signal processing protocol described in this thesis. In more realistic corrosion experiments, where temperature changes were of the order of 4 C), it was shown that a wall thickness loss of 1 micron can be detected reliably by applying the same measurement protocol. Another major issue affecting both accuracy and precision is changing inner wall surface morphology. Ultrasonic wave reflections from rough inner surfaces result in distorted signals. These distortions significantly affect the accuracy of wall thickness estimates. A new signal processing method, Adaptive Cross-Correlation (AXC), was described to mitigate the effects of such distortions. It was shown that AXC reduces measurement errors of wall thickness loss rates by an order of magnitude compared to standard signal processing methods so that mean wall loss can be accurately determined. When wall thickness loss is random and spatially uniform, 90% of wall thickness rates measured using AXC lie within 7.5 ± 18% of the actual slope. This means that with mean corrosion rates of 1 mm/year, the wall thickness estimate with AXC would be of the order of 0.75-1.1 mm/year. In addition, the feasibility of increasing the accuracy of wall thickness loss rate measurements even further was demonstrated using multiple sensors for measuring a single wall thickness loss rate. It was shown that measurement errors can be decreased to 30% of the variability of a single sensor. The main findings of this thesis have led to 1) a solid understanding of the numerous factors that affect accuracy and precision of wall thickness loss monitoring, 2) a robust signal acquisition protocol as well as 3) AXC, a post processing technique that improves the monitoring accuracy by an order of magnitude. This will benefit corrosion mitigation around the world, which is estimated to cost a developed nation in excess of 2-5% of its GDP. The presented techniques help to reduce response times to detect industrially actionable corrosion rates of 0.1 mm/year to a few days. They therefore help to minimise the risk of process fluid leakage and increase overall confidence in asset management.

Bird strike poses a great hazard to aircraft components, such as the engine and windshield, during flight. Thus, it is critical to understand the impact resistance of key aircraft components under bird strike. During this PhD study, Aluminium Alloy 2024-T3 and laminated glass interlayered with thermoplastic polyurethane (TPU), which are commonly used as the materials of the aircraft fuselage and windshield respectively, are selected as impact target materials. Both laboratory-based experiments and finite element simulations are performed using a light gas gun and ABAQUS/EXPLICIT respectively. A good agreement is achieved between the experimental work and numerical predictions for the impact response. Two bird substitute materials were selected: RTV rubber and ballistic gelatine, whose dynamic pressure profiles are similar to that of a real bird during a high speed impact. Mechanical properties of both materials were investigated by conducting compression tests at quasi-static (0.25, 2.5 and 25 min-1) and intermediate rate (2760 min-1 to 22500 min-1). As a result, the relationship between true stress and strain is obtained and constitutive equations are established using the hyperelastic models, i.e. the Ogden, Mooney-Rivlin and Neo-Hookean. The 3D Digital Image Correlation technique was employed in the gas gun test of the AA 2024-T3 and TPU interlayered laminated glass. Thus, the impact compliance of both targets from rubber and gelatine impacts are attained and found to be roughly equal to the same initial projectile momentum. An FE simulation was used to model the experimental process and was validated against the DIC results. Moreover, the Hugoniot pressure plays a predominant role in laminated glass fracture during the impact, with the rubber projectile leading to a larger damage than the gelatine projectile given the same momentum. This is because the shock wave speed in the rubber is larger than that in the gelatine projectile. A validated FE simulation is therefore presented, which can be used to simulate real bird impact on real aircraft structures in the future. Thus, this PhD work can be potentially implemented into industrial research programmes to aid design and optimisation.

The detection of corrosion on insulated and/or coated pipes in the oil and gas industry remains a challenge. Routine inspection, which is commonly achieved with in-line tools known as "pigs", is not possible where there is any risk of the pig becoming stuck. There are thousands of kilometers of pipe worldwide deemed ''unpiggable'' whose safety must be ensured using Non-Destructive Evaluation (NDE) external to the pipe if potentially catastrophic failure is to be avoided. Many NDE techniques lack sufficient sensitivity due to the coating thickness producing a high standoff distance between the pipe and the sensor and therefore require costly and time-consuming removal of the coating. A method capable of detecting and/or monitoring of defects (e.g. one-third-wall depth corrosion) while leaving the insulation/coating intact would be highly attractive. This thesis documents the development of a technique in which a low-frequency AC current is directly injected into the pipe at distant locations, and perturbations in the magnetic field caused by "current deflection" around defects are measured using solid-state magnetic sensors. Two methods of applying this novel technique were investigated. Firstly, scanning the sensors to measure perturbations in the field and screen for defects, and secondly, permanently installing sensors outside the pipe for Structural Health Monitoring (SHM). A Finite Element (FE) model has been developed and used to investigate the practical challenges that are faced by the technique and how these may be overcome. The sensitivity of the technique for defect detection by external pipe scanning in a practical scenario has then been evaluated using a model-assisted Probability of Detection (POD) framework that combines the measurements of the signal from an undamaged pipe with synthetic damage profiles and contributions from general corrosion and sensor misalignment. The results indicate that good performance is expected for damage detection by scanning above a typical insulation thickness with just a few amps of injected current. A similar framework has then been used to evaluate the sensitivity of the technique as an SHM solution which suggests excellent corrosion detection performance with the permanent installation of inexpensive magnetic sensors. The technique has potential advantages over competing methods in both scanning and monitoring modes and there are many opportunities for future development.

The demand for CO2 emission reduction for modern road vehicles has seen engine downsizing become a key trend in internal combustion engine design: a smaller engine has reduced pumping, frictional and heat losses, and therefore better fuel economy. Turbocharger technology is one of the enabling technologies, offering lower specific fuel consumption and producing more power for a given engine capacity. The turbocharger matching process, which specifies an appropriate turbocharger design for a particular engine, is crucial in obtaining optimum engine performance. In order to achieve a high level of accuracy in the system-level prediction, high fidelity turbocharger models are required; but such models have not yet reached fruition. The present study has assessed the effect of preserving the exhaust pulse energy from an engine right through to the turbine on the steady and transient engine performance. A combination of appropriate turbine sizing and pulse-divided exhaust manifold was applied, and as a consequence, lower back pressure and improved engine scavenging reduced residual content by 28%, while the brake specific fuel consumption (BSFC) improves by approx. 1.2% on average over speed range. Furthermore, the implementation of electric turbo assist (ETA) system on the engine results in better fuel economy by 2.4%. The present work has also assessed the overall engine performance using a commercial 1-D gas dynamics simulation tool by modelling the waste-gated turbines in a novel manner. This approach has been validated experimentally. The study also examined the benefits of electric turbocharger systems for a highly-downsized engine, a modified version of the baseline engine. Some potential multi-boosting systems were applied, and the overall benefits in terms of engine performance were assessed. An integration of an electric turbocharger and a low-pressure turbine with electric turbo compounding gives the best advantages particularly in pumping loss, residual and transient performance while improving fuel economy in comparison with other systems.

The ability to obtain fast and accurate solutions of the neutron transport equation is of great importance for various reactor physics and radiation shielding applications. This thesis first presents an overview of the techniques used to solve the neutron transport equation using discontinuous Galerkin finite element methods. It then presents two sets of techniques which aim to improve the effectiveness of a neutron transport code and provides various computational results to support their effectiveness. The first methods studied are two preconditioners designed to accelerate the solution of the neutron diffusion equation which in turn is used to accelerate the neutron transport equation using diffusion synthetic acceleration. They are first presented in a form appropriate for solving finite element problems using first-order basis functions, and then expanded so that they may be used on problems containing second and higher-order basis functions. The second study is for sets of basis functions for pyramid finite elements used in the solution of neutron transport and neutron diffusion problems, demonstrating the effectiveness of these elements in comparison to other element types. This thesis provides substantial evidence for the effectiveness of the methods described alongside an analysis of where their use is appropriate. Numerous computational examples are used, including several reactor physics and radiation shielding benchmark problems obtained from benchmark specifications. These serve to demonstrate the strengths and in some cases the weaknesses of the techniques presented. The methods presented have significant practical applications in the fields of reactor physics and radiation shielding.

Current standard techniques used for anterior cruciate ligament reconstruction are unable to restore normal knee biomechanics. One explanation for this is that ongoing anterolateral rotatory instability is due to damage to anterolateral knee structures that current surgical techniques fail to address. Focus had previously moved away from the periphery of the knee towards intra-articular reconstruction, however in the past rotational instability was addressed with a lateral extra- articular tenodesis, and these were widely used techniques in the 1970s and 80s before falling out of favour. A detailed review of this surgery, including the Lemaire, Macintosh and Ellison procedures has been performed in this thesis, as well as a review of the pre existing anatomical knowledge of the anterolateral knee structures. Due to gaps in knowledge identified, an attempt to further define anterolateral knee anatomy has been made. 40 fresh frozen cadaveric knees have been dissected. A consistent structure termed the anterolateral ligament (ALL) was identified in 33 (83%) of the specimens. The ALL passed antero- distally from a femoral attachment point posterior and proximal to the lateral femoral epicondyle. It passed superficial to the lateral collateral ligament, to an attachment point midway between Gerdy’s tubercle and the fibula head. We sought to further determine the biomechanical role of the structure using length change experiments. The ALL was isometric from 0° to 60° degrees of flexion, and then slackened when the knee was flexed to 90°. Two independent musculoskeletal radiologists reviewed MRI appearances of the ALL and findings were consistent with our anatomical observations. The ALL may be involved in resisting the pivot shift and inserts at the site of the Segond fracture. Since the experiment numerous anatomical, biomechanical and radiological investigations have been published on the ALL and these are reviewed in detail.

Turbulent flows involving heat transfer or chemical reactions are important processes in the operation of numerous devices such as engines, and heating and cooling systems. Laser-based measurements of flow temperature and velocity have aided our understanding of the underlying flow physics in such processes. Recently, micron-size thermographic phosphor tracer particles, which are solid materials with temperature-dependent luminescence properties, have been exploited for simultaneous temperature and velocity imaging. However, the measurement strategy, which requires pulsed lasers to illuminate and excite the particles, is typically implemented at low temporal (~10 Hz) and spatial resolutions (>400 μm). Also, it is difficult to implement the technique for near-wall measurements or where limited optical access is required. In this dissertation, an alternative and complementary single-point measurement technique is presented, also based on thermographic phosphor particles. Here, particles seeded in a flow are probed individually when crossing a probe volume formed using continuous wave (CW) lasers. Using photomultiplier tubes to detect the scattering and luminescence signals from the same particle, velocimetry and thermometry are performed simultaneously, at sampling rates up to kHz’s and spatial resolution of 150 μm using a combined laser Doppler velocimetry and phosphor thermometry technique. The development of this measurement technique, based on the two-colour ratio strategy in phosphor thermometry is first described. The technique is demonstrated, using the phosphor BaAl10Mg17:Eu2+, in a heated jet from 293 - 670 K with temperature precision of 4-8%, and accuracy better than 2%. The utility of the technique is further demonstrated for near-wall measurement with accurate measurements performed as close as 200 μm from a heated surface. Another temperature evaluation strategy, which exploits the temperature dependence of the luminescence lifetime, by probing the phase-shifted luminescence from the same phosphor particles when using a modulated excitation source, is also described. The concept is demonstrated in a heated jet above 600 K, with a measurement precision as high as 1% obtained at 840 K. A discussion on applications and future developments of the concept of the ‘thermographic laser Doppler velocimetry’ is also provided.