The present investigation is part of a long term research programme dealing with the wave action in the exhaust and induction pipes of a two-stroke oil engine and their effect upon the cylinder scavenge process. As a development of fundamental researches carried out at the University Laboratories using simulated cylinder release pressures in a motored engine, the present investigation seeks to extend the established data to the practical problem of the engine under firing conditions. In this report, the theoretical analysis of unsteady one-dimensional gas flow, all owing for the effects of wall friction, heat exchange with the surroundings, and temperature discontinuities is developed, and the Method of Characteristics is applied to effect a solution. Theoretical exhaust pipe and cylinder indicator diagrams are evaluated using this theory, and compared with the experimental diagrams from the firing engine. From performance trials, the measured air consumption using a constant air/fuel ratio, but different exhaust pipe lengths and engine speeds, is evaluated and plotted on a dimensionless basis for comparison with the previous simulated work.

Laser micro-machining (LMM) is an attractive manufacturing technology for the fabrication of a wide range of micro-components due to its intrinsic processing attributes. In addition, LMM can be integrated in hybrid manufacturing platforms and thus to combine LMM with other complementary processes for the cost effective fabrication of a broader range of miniaturised products. Nevertheless, the broader industrial uptake of LMM is still to come due to system-level issues in designing and implementing LMM systems. In this context, the research reported in this thesis is aimed at improving the system-level performance of reconfigurable LMM platforms and thus to create the necessary pre-requisites for achieving a much better machining accuracy, repeatability and reproducibility (ARR) in different processing configurations. First, a systematic approach for assessing and characterizing the manufacturing capabilities of LMM platforms in terms of ARR is proposed. Then, the development of generic integration tools for improving the system-level performance of reconfigurable LMM platforms in terms of manufacturing flexibility and reliability both as stand-alone machine tool configurations and also as component technologies in multi-process manufacturing solutions is presented. Next, generic software tools are proposed and validated for improving the manufacturing capabilities of LMM systems for realizing complex multi-axis laser processing strategies with a closed-loop manufacturing control. Finally, the integration of LMM in process chains is validated to extend the capabilities of well proven conventional manufacturing routes, i.e. micro milling, for the fabrication of miniaturised products, i.e. Terahertz technology devices, which have complex and challenging-to-fabricate functional features and overall designs.

This PhD project set out to tackle the disadvantages of brittleness and low corrosion resistance that ceramics and mild steel bear respectively by developing ceramic and metallic nanocomposites using nanostructured fillers. Graphene platelets (GPLs) as newly emerging carbon materials were chosen as the reinforcing fillers. Two types of nanocomposites were fabricated and their mechanical or corrosion resistant properties were characterized. Alumina (Al2O3) based nanocomposites reinforced with GPLs were sintered and GPL/Nickel (Ni) nanocomposites were produced using an electrodeposition technique. The results show that the mechanical properties of the ceramic matrices are significantly improved by adding nano fillers. Toughening mechanisms induced by GPLs, such as pull-out, crack deflection and crack bridging are observed. On the other hand, the mechanical and corrosion resistance properties of Ni matrix are greatly enhanced by the addition of GPLs. In addition, the higher percentage of GPLs results in finer and more uniform Ni microstructures, leading to the higher hardness and corrosion resistance.

An improved approach to the classical Rassweiler and Withrow’s mass fraction burned model and an improved data acquisition/processing procedure are employed with the intention of increasing precision while retaining simplicity. A new method to predict the trends of MFB and emissions, based on the online analysis of cylinder pressure is introduced. A diagnostic method to study the heat release rate in a natural gas fuelled engine has been developed for future use. Natural gas fuelled vehicles are environmentally friendly and it is possible to use a high compression ratio engine with all its associated benefits for efficiency. However, one of the problems associated with the use of natural gas is NOx emission. EGR can be used to reduce NOx, but it leads to unstable combustion. The stability problem can be resolved by the addition of hydrogen, which can be provided by fuel reforming. Based on the beneficial effects of exhaust gas fuel reforming, the effects of EGR, H2 and H2/CO as additives to natural gas are analysed and discussed in terms of combustion indicators derived by the new diagnostic method, in particular in terms of combustion duration (CA for 5/50/95% MFB), IMEP and cycle by cycle variation (COV of IMEP, COV of peak pressure).

Wear debris are known to incite a variety of biological responses when released from a joint replacement device. One such response is known as osteolysis-pathological destruction of bone. Osteolysis is the major cause of failure in joint replacements. The loss of bone around a joint replacement may cause an aseptic loosening of the implant and reduce options for revision surgery. The intervertebral disc may be replaced with a joint replacement device. Often, this is done with a ball on socket joint using a metal-on-polymer material combination. Ultra-high molecular weight polyethylene (UHMWPE), inherited from hip and knee implants, is a common choice in lumbar disc replacements. The wear debris from a Charité implant, tested in vitro, was characterised using computer vision techniques and machine learning. It was found that wear debris from this UHMWPE and metal implant produce debris that are particularly prone to illicit an immune reaction that could lead to osteolysis. To counter the release of wear debris into periprosthetic tissue where it can do harm, laser sintered Polyetherketoneketone (PEKK) was wear tested in an attempt to capture wear debris in the surface voids formed by the manufacturing process. Despite literature suggesting this could work, wear tests showed sintered PEKK is unsuitable as a bearing material.

The participation of small and medium enterprises in inter-firm collaboration can enhance their market reach while maintaining production lean. The conventional centralised collaboration approach is believed to be unsustainable, in today’s complex environment. The research aimed to investigate manufacturing network collaborations, where manufacturers maintain control over their scheduling activities and participate in a market-based event, to decide which collaborations are retained. The work investigated two pairing mechanisms where the intention was to capture and optimise collaboration at the granular level and then build up a network from those intermediate forms of organisation. The research also looked at two bidding protocols. The first protocol involves manufacturers that bid for operations from the process plan of a job. The second protocol is concerned with networks that bid for a job in its entirety. The problem, defined by an industrial use case and operation research data sets, was modelled as decentralised flow shop scheduling. The holonic paradigm identified the problem solving agents that participated in agent-based modelling and simulation of the pairing and the bidding protocols. The protocols are strongly believed to achieve true decentralisation of scheduling, with good performance on scalability, conflict resolution and schedule optimisation, for the purpose of inter-firm collaboration.

A novel methodology for series-parallel systems’ reliability optimisation has been proposed developed and tested. It formulates the problem as a multi-criteria optimisation, to maximise the subsystem reliabilities while minimising the system cost modelled as a penalty function of component reliabilities, with lower bound constraints on the subsystems’ reliabilities. The goal was to find the Pareto optimal component reliability values that at least yielded a system reliability target. This problem usually occurs at the system design stage. The resultant continuous optimisation model was solved by the Weighted Sum method. The methodology was applied to hypothetical problems and to cases derived from published work concerned with life support and electricity transmission systems’ reliability. It was also tested on a gas transmission system. A comparison of the results with those for a single criterion optimisation model of the life support system indicated that higher reliability could be generated for the components/system under the methodology. The relative levels of the component reliability values were consistent with those achieved under the single criterion formulation. The reliability values allocated to a component was also consistent with their importance. The cost/penalty increased with increase in component reliabilities, becoming indeterminate as component reliability approached its maximum value.

A once-through flowing rig built entirely from 316L stainless steel (SS316L) was used to study dissolution and particulate release behaviour of corrosion films on SS316L surfaces in simulated PWR primary coolant. Coolant of pH25C 9-11 was prepared using LiOH in nitrogen-sparged ultrapure water, and pumped at 0.1-2 g/min, under ~100 bar pressure and temperatures up to 300 °C. Flow velocity was at most 6.4 mm/s in 1⁄4” tubing, and 0.13 mm/s in 1” bore tubing where the bulk of the volume resided. Levels of the five most prevalent alloying elements – Fe, Cr, Ni, Mo, Mn – were analysed in rig effluent samples using ICP-MS. Nitrocellulose filters (0.05-3.0 μm) were used at the point of sampling to assess the contribution from particulate and colloidal matter. In most runs, SS316L surfaces of the rig acted as the sole source of corrosion products. Levels of Fe, Cr, and Ni were generally in the low ppb range, consistent with solubility, though transients to higher levels occurred. Levels of Mo and Mn varied with time and flow rate, sometimes exceeding 100 ppb, and cumulative release, particularly of Mo, appeared to be greater than could be accounted for by non-selective oxidation, suggesting leaching from the SS316L subsurface.

The thesis presents investigations of advanced combustion strategies in a modern V6 diesel engine fuelled with mineral diesel and Tallow Methyl Ester (TME)-diesel blends, in order to meet future emissions legislation. One of the main objectives of this research is to improve fuel consumption whilst minimising engine emissions through the combined effects of injection strategy (fuel injection pressure, dwell period, pilot fuel quantity) and cooled Exhaust Gas Recirculation (EGR) on a modern V6 common rail direct injection diesel engine. In the case of using EGR (49–52%) at 1500 rpm and 10% of engine peak torque, by increasing the fuel injection pressure from 300 to 800 bar, engine thermal efficiency increased from 16.5 to 19.1% and 17.1 to 19.7%, BSFC decreased by 13.5% and 13.2%, smoke level decreased by 74.3% and 70.1% and NOx emissions increased by 69.6% and 68.0%, respectively for a short (5 CAD) and a long (40 CAD) dwell period. In addition, the study of a variation of pilot fuel quantities (0.8–3.0 mg/stroke) with a fixed dwell period (5 CAD) at two different fuel injection pressures (250 bar and 800 bar) shows that the smaller pilot quantity with the higher fuel injection pressure can be considered as an enhanced strategy to control engine performance and emissions simultaneously. Therefore, the combination of higher injection pressure, longer dwell, smaller pilot quantity and the use of EGR could potentially improve fuel consumption and minimise engine emissions. The use of TME-diesel blends results in lower engine thermal efficiency and higher fuel consumption and NOx emissions. In the case of 1500 rpm and 25% of engine peak torque, the combustion of TME10 and TME30 reduced the engine thermal efficiency from iii 35.3 to 33.7% and 35.3 to 33.2% and increased the BSFC by 4.9% and 6.5%, respectively. At the same engine condition, the combustion of TME-diesel blends increased NOx emissions by 1.8% and 10.0% and reduced CO by 0.9% and 1.8%, THCs by 18.0% and 23.9 %, smoke by 30% and 51.7% for TME10 and TME30 respectively. However, the engine thermal efficiency, BSFC and NOx emissions could be improved with the application of the combined effect of injection strategy (fuel injection pressure, dwell period, pilot fuel quantity) and EGR as shown in the first phase of this study.

The thesis is focusing on the potential roles and applications of NH3 in transportation area, where ammonia is applied i) as a hydrogen carrier involved in a catalytic reforming process tor H2 production, ii) in its reformed form i.e. H2-NH3 mixture for improved NH3 combustion in CI engines (as a carbon-free energy carrier), and iii) as a reductant in engine emission abatement under the incorporation of the NH3 reforming mechanism and catalytic aftertreatment systems. To implement the above studies, a prototype reformer system and a catalytic reaction mechanism were designed and proved capable of producing Hz-contended reformate. The reformed NH3 i.e. H2-NH3 mixture was later applied in diesel operation and demonstrated successful engine decarbonisation. With a further incorporation of a Silver/Alumina catalyst in the engine exhaust system, the reformate was revealed as viable reductant for low temperature NOx abatement. Therefore, a combination of the studied systems show a great potential in simultaneous diesel engine emissions reductions, which include CO2, CO, HC, PM and NOx.