The aim of this PhD thesis is to develop a one-dimensional (1D) mathematical model to study in designing and improving emission control systems such as those in Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF). This was achieved by capturing the fundamental reaction kinetics from the microreactor data within the careful choice of concentrations/ temperatures domain; together with good understanding of the physical phenomena’s occurring in these systems. When considering a DOC, it is important to have a good description of the catalyst activity as a function of Platinum Group Metal (PGM) loading, which in this case is Pt, this enables mathematical models to be used in the optimization of the PGM loading. The work presented here looks at the design of a DOC based aftertreatment system through development of kinetics from data obtained from the microreactor for a wide range of PGM loadings (2.5-75g ft-3). The variation in catalyst activity with different PGM loadings for the key reactions was determined. The model developed in this study predicts well all the experimental data for the various loadings. DPF is another important aftertreatment technology that is used for the control of Particulate Matter (PM) emission from diesel engines. Under favourable conditions, the soot collected on the filter can be removed by oxidation with NO2 from temperatures as low as 200°C. The work presented in this thesis shows the fundamental modelling approach to develop kinetics for soot oxidation by NO2. The selectivity to CO was found to differ only marginally with temperature, and is independent of NO2 concentrations. By modelling these data using a 1D model, the rate equations for the soot-NO2 reaction were determined, and experimental data were predicted.

Surface damage can be introduced into rotor disc components during assembly, maintenance and overhaul operations for aircraft engines. This is known as handling damage and is often in the form of surface scratches, which are known to reduce total component fatigue life. This work provides a holistic understanding of the effect of artificial scratch damage on the fatigue performance of a nickel-based superalloy used for compressor and turbine disc applications. Following extensive analysis of results from previous test programmes completed at Rolls Royce plc., a series of low cycle fatigue tests were performed on Alloy 720Li specimens. A test matrix was designed to isolate and identify every factor that may contribute to the fatigue properties of scratch damaged components. The geometry of a scratch, which causes a local stress concentration and increases the ‘effective Kt’ at the scratch root, is the most significant factor in controlling fatigue performance. Scratches cause a decrease in crack initiation life, thereby reducing total component fatigue life. Compressive residual stresses induced by shot peening and the scratching process itself are beneficial to component life. Varying levels of scratch damage were fully characterised by scanning electron microscopy, microhardness testing and electron backscatter diffraction to show the severe microstructural modification and increased hardness caused by the scratching process. Computational modelling was carried out to determine geometrical effects of scratches on local stress and strain fields. The ‘effective Kt’ values under scratches were calculated, which helps to predict fatigue performance. This type of comprehensive investigation is important for damage tolerance lifing approaches and helps to minimise premature component retirement.

Different Global Navigation Satellite System (GNSS) constellations are available these days. This has led to an increase in the number of satellites available for the user, and that presents different performance levels for the user requirements like accuracy and convergence time. However, these benefits come from different constellations that have different reference times and for some, different frequencies. At the same time, the Precise Point Positioning (PPP) has also been presented as being a position solution within a certain level of accuracy and precision. Therefore, it is important to investigate the potential benefits from the PPP with a view to using a single or multi-constellation. These investigations include accuracy, precision, and convergence time. In addition, it is important to look at the individual performance of these constellations regarding the above improvements. This will give a clear decision about adopting a single or multi-constellation. It will also provide an independent solution, for instance for the station coordinates and troposphere, and independent estimated station velocities, without additional cost. This research has been conducted in three stages. Firstly, the research begins with an evaluation of the GPS and the GLONASS (GLO) constellation geometry using a new approach for computing the cumulative dilution of precision (DOP) rather than the conventional DOP which was found to be latitude-dependent. Then it investigates the achievable station coordinate accuracy from PPP scenarios for static positioning after choosing the most appropriate PPP strategy that needs to be followed. Furthermore, the effect of different precise products (satellite orbits and clocks) on the PPP solutions and the difference between those products has been covered. It has been proven that PPP solutions can reach the same precision as a Global Double-Difference (GDD) GPS solution. Most importantly, the PPP GLO is found to be capable of producing similar precision and accuracy when compared to PPP GPS as well as the GDD GPS solution. Secondly, this research also investigates the conventional strategy (using a model for the hydrostatic component and estimating the wet component) for estimating the troposphere Zenith Total Delay (ZTD) from the PPP solutions with an evaluation of the obtained accuracy of the tropospheric ZTD from four tropospheric models. It also presents an alternative strategy (estimating both components using different mapping functions and different process noises) for estimating the tropospheric ZTD from the PPP that can give millimeters of ZTD accuracy without affecting the station coordinate estimation and without relying on any metrological data or models. Validations have been conducted for the new strategy using PPP GPS, PPP GLO and PPP GPS+GLO. Regional validation was conducted over seven consecutive days for seven weeks, using the Ordnance Survey of Great Britain (OSGB) stations in the UK, and long-term (over one year) validation was conducted using 22 stations from the OSGB. The regional and long-term validations have been conducted using three different final precise products (satellite orbits (SP3) and clocks (CLK)), which are the EMX, ESA and GFZ. A global validation using ~76 IGS stations was conducted over a different period. This was conducted in three stages, using the final EMX, final IGS and real-time IGS precise products. It was found that this approach can be used in real-time as well as in post processing without a significant difference between the results. Finally, this research has investigated the potential of using the PPP GLO for crustal motion separate to using the PPP GPS. Consistent horizontal station rates were found between PPP GPS and GDD GPS solutions. It was also concluded that it should be possible to use the PPP GLO for crustal motion, as an independent and precise solution. However, there was a bias in the orientation components of the estimated horizontal station rates between the PPP GLO and both other solutions (PPP GPS and GDD GPS), which was concluded to be a system bias rather than a strategy bias.

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Within this thesis, a broad range of microscopic and spectroscopic methods are employed to investigate crystallisation processes initiated at novel functionalised interfaces. This approach combines in situ optical microscopy (OM) with several surface sensitive techniques, including atomic force microscopy (AFM), scanning electron microscopy (SEM) and interferometry, with further structural analysis provided via Raman spectroscopy and X-ray diffraction (XRD). This method allows the key mechanistic phenomena to be elucidated to a high level of detail for crystal growth processes with extreme industrial and biological importance. The main focus of the thesis is around a specific industrial problem, concerning the detrimental growth of inorganic crystalline materials within internal combustion engines. Firstly, the deposit structure is revealed by implementing analytical techniques such as SEM, Raman spectroscopy and XRD to characterise real engine deposits. This in depth analysis demonstrates the high abundance of the calcium sulfate polymorphs bassanite (CaSO4⋅0.5H2O) and anhydrite (CaSO4) within the deposit, providing initial insights into this unfavourable growth process. These deposit growth mechanisms are further studied via in situ OM, monitoring calcium sulfate crystallisation at aqueous-organic liquid-liquid interfaces to mimic real life conditions within the engine environment. As well as providing a wealth of knowledge on the deposit formation process, this approach highlights the unique properties liquid-liquid interfaces offer for crystal growth, revealing via Raman spectroscopy and XRD analysis their applicability for synthesising typically unstable materials under low energy, ambient conditions. This industrial problem is further investigated by studying the surface reactivity of the growing calcium sulfate mineral faces via AFM force spectroscopy. This allows interaction forces between the deposit surface and different additive chemistries to be quantitatively determined in an oil-based environment, opening up methods for preventing deposition on engine surfaces. Unexpected, low adhesion values are obtained between polar additive head groups and the polar crystal deposit surface, a consequence of electrostatic repulsion. Thus, this work reveals key aspects related to the structure of charge in organic environments, an area still under much debate. The last chapter of this thesis switches focus to one of the key minerals responsible for engine deposit growth, calcium carbonate. Charged graphite interfaces are implemented to study their effects on the oriented nucleation and polymorphism of this crystal system, in the absence of defects and chemical functionalities. This highlights the significant role electrostatics play in nucleating high energy crystal planes and polymorphs, which is of huge importance for biomineralisation, and scale-prone, charged industrial surfaces. Overall, this thesis elucidates the unexplored properties of two highly relevant functionalised crystal growth interfaces, demonstrating their importance for preventing deposit growth, as well as their diverse application for the synthesis of high energy crystalline materials.

Threats of high crosswind gusts on running safety of modern road and rail vehicles have been reported around the world. Under high transient crosswind conditions, sudden changes in vehicle aerodynamic forces can lead to adverse effects on vehicle dynamics and stability. Moreover, due to increase in maximum speed limits and body dimensions of commercial vehicles as well as reduction in their weights, large class vehicles, in particular, are more prone to rollover accidents in strong crosswind situations, especially at cruising speeds or at exposed sites. Such crosswind accidents have been observed even at low vehicle speed of 15 m/s in adverse windy weather. It is therefore essential to conduct detailed investigations on the aerodynamic performance of commercial vehicles under crosswind conditions in order to improve their crosswind stability. In this study, estimation of unsteady aerodynamic forces acting on a high-sided tractor-trailer vehicle have been carried out based on experiential and numerical simulations. Although natural crosswind gusts are high-turbulent phenomena, and have a large variability in types and origins, this study suggests employing two gust scenarios based on two different methods: 1. Transient wind gust scenario developed in wind-tunnel to represents a high-sided tractor semitrailer vehicle moving on a road in moderate wind condition and immediately being hit by wind gust. 2. Deterministic crosswind scenario with gusts in exponential shapes has been considered to predict crosswind aerodynamic forces of a high-sided tractor semitrailer vehicle moving through wind exposed area. This scenario is specified in the Technical Specification for Interoperability (TSI) standard, but it has been employed in this study in combination with Computational Fluid Dynamics (CFD). A series of time-dependent crosswind aerodynamic forces acting on the tractor-semitrailer vehicle have been predicted. Moreover, to illustrate the potential influence of crosswind gusts on a high-sided tractor semitrailer vehicle, instantaneous gust flow structures for proposed wind scenarios and wind pressure fields were presented. The results show that both wind gust scenarios have significant unsteady effects on the side aerodynamic force and the roll moment of the vehicle. Furthermore, there are significant variations in aerodynamic loads, and the flow field becomes more complicated, consistent with the gust’s strength. These conclusions strongly suggested the importance of considering the unsteady aerodynamic forces in the analysis of heavy vehicle roll dynamics. Lateral load transfer ratio (LTR) is a criterion that is often used for designing ground vehicle rollover warning technologies to indicate the vehicles rollover status. Generally, LTR index depends on road geometry and vehicle dynamic characteristics. However, as mentioned above, crosswind loads have the potential to influence the roll stability and therefore the safety of large commercial vehicles. Therefore, this thesis presents the research carried out to improve the traditional LTR for a high-sided tractor semitrailer vehicle to be more efficient in crosswind environment. For this purpose, since experimental investigations on vehicle rollover dynamics are difficult to carry out, a coupled simulation of crosswind aerodynamic forces and multi-body vehicle dynamics has been proposed. In this method, the predicted aerodynamic forces result due to the proposed wind scenarios were input into multi-body dynamic simulations of the tractor semi-trailer vehicle that were performed through Adams/Car software. Based on this coupled analysis, dynamic responses of the vehicle to fluctuating crosswind conditions have been predicted. Moreover, all parameters of the LTR index such as body roll angle and lateral acceleration were estimated through a critical turning manoeuvre with crosswind actions. The investigation results show that, in the same manoeuvre, in comparison with the traditional LTR index (i.e., in which crosswind aerodynamic forces are ignored), the improved LTR rollover (crosswind) indicator, has successfully detected wheel lift–up conditions when crosswind aerodynamic loads are considered. Also, average values of the LTR measured under crosswind effects are about 22% higher than those of corresponding traditional LTR index. Therefore, the rollover indicator that has been improved by the proposed methodology can provide more reliable information to the warning or control system in the presence of wind conditions.

Analysis of fatigue samples sectioned from commercial 319 (Al-Si-Cu-Mg) alloy cylinder block castings showed that shrinkage pore networks and oxide films played an important role in fatigue failure. A reduced pressure technique was employed to study the relationship between porosity and oxide films. Links between oxide films and porosity were made and mechanisms for the inflation of films into porosity networks were established. Tensile tests performed on samples cast with and without filters showed that the ultimate tensile strengths of the filtered group had a Weibull modulus 2.4 times that of the unfiltered. Samples with abnormally low strengths were found to contain oxide film defects. These films had an approximately 5 times greater damaging effect on strength than that predicted by reduction in cross sectional area. The fracture strengths of these flawed samples were found to obey a linear elastic fracture mechanics model (LEFM). A LEFM crack growth model was particularly successful in predicting the life of fatigue samples that initiated at oxide films. Having crack-like geometry, and a minute crack tip radius, oxide films effectively acted as preformed cracks. Consequently there was an absence of crack nucleation time, explaining the correlation of predicted propagation life to fatigue life.