The work presented in this thesis is intended to investigate the effects of fuel properties, injection strategy and timing on autoignition and combustion characteristics of a Homogeneous Charge Compression Ignition (HCCI) engine with a negative valve overlap (NVO) strategy. Conventional (pressure-transducer based) measurements and passive optical research have contributed to understanding of the chemical-physical sites of HCCI autoignition and combustion. This experimental work was undertaken on matching thermal and optical single cylinder research engines in configurations derived from a production Jaguar V8 engine. A thermal engine study using a range of fuels including conventional gasoline and primary reference fuels has been performed to gain insight into autoignition and combustion characteristics of various chemically dissimilar blends or components. This was done at different operating conditions by varying the engine speed and the proportion of residuals trapped. These measurements have shown that the autoignition and combustion characteristic of an HCCI operated engine are highly dependent on fuel blend composition and are also affected by engine operating conditions. It was found that the autoignition process type which the mixture undergoes, whether it is one- or two-step, depends very strongly both on fuel blend composition and on engine operating conditions. More specifically the presence and also proportion of particular chemical compounds in a blend could significantly contribute to the alteration of the process type. Similar experiments using the chosen engine operating points were repeated on the optical engine using passive optical diagnostics such as imaging and spectroscopy. Thereby it was possible to gain insight into the chemistry of one-step and two- step ignition processes. The image analysis of the port fuel injected (PFI) HCCI operation have been carried out for stoichiometric and lean conditions. A crank-angle resolved high-speed imaging technique was employed a piston crown window for optical access to the combustion chamber. The spatial repeatability nature of autoignition occurrence and the directions of combustion progress were evaluated using especially developed image processing technique. The insight into the expansion rates of burned areas and of the spreading velocities of reacting structures fronts was also gained by introducing two new image processing techniques. Various direct injection strategies (single and split injection) and timings, including fuel injection prior to and during the negative valve overlap period were optically investigated. The comprehensive study included the application of three diagnostic instruments: the Complementary Metal-Oxide Semiconductor (CMOS) high-speed colour imager, the intensified Charge Couple Device (CCD) and the imaging spectrograph. Among the other observations the applied passive techniques, the imaging and the spectroscopy in conjunction with adequate image processing techniques have shown that the combustion behaviour and also the colour of the burning mixture are dependent on the fuel injection scheme. With the investigated split (double) injection, when some of fuel is injected prior to TDC NVO the combustion behaviour is significantly different than when it is injected during even at TDC (NVO). There is a strong indication that a form of incandescence occurs during the NVO, which probably comes from the glowing soot. This is further supported by a quantification of the emitted luminescence and spectroscopic measurements during this phase.

Pad printing is used to decorate consumer goods largely because of its unique ability to apply graphics to doubly curved surfaces. The Intelpadrint project was conceived to develop a better understanding of the process and new printing pads, inks and printers. The thesis deals primarily with the research of a printer control system including machine vision. At present printing is manually controlled. Operator knowledge was gathered for use by an expert system to control the process. A novel local corner- matching algorithm was conceived to effect image segmentation, and neuro-fuzzy techniques were used to recognise patterns in printing errors. Non-linear Finite Element Analysis of the rubber printing-pad led to a method for pre-distorting artwork so that it would print undistorted on a curved product. A flexible, more automated printer was developed that achieves a higher printing rate. Ultraviolet-cured inks with improved printability were developed. The image normalisation/ error-signalling stage in inspection was proven in isolation, as was the pattern recognition system.

It is critical to ensure that a 5-axis machine tool is operating within its geometric tolerance. However, there are various sources of errors influencing its accuracy; testing them with current methods requires expensive equipment and long machine down time. This motivates the development of a simple and fast way to identify and characterise geometric errors of 5-axis machine tools. A method using a Double Ball Bar (DBB) is proposed to characterise rotary axes Position Independent Geometric Errors (PIGEs), which are caused by imperfections during assembly of machine components. An established method is used to test the same PIGEs, and the results are used to validate the developed method. The Homogeneous Transformation Matrices (HTMs) are used to build up a machine tool model and generate DBB error plots due to different PIGEs based on the given testing scheme. The simulated DBB trace patterns can be used to evaluate individual error impacts for known faults and diagnose machine tool conditions. The main contribution is the development of the fast and simple characterisation of the PIGEs of rotary axes. The results show the effectiveness and improved efficiency of the new methods, which can be considered for 5-axis machine tool maintenance and checking.

Small scale distributed compressed air energy storage (D-CAES) has been recognized as promising technology which can play major role in enhancing the use of renewable energy. Due to the transient behavior of the compressed air during the discharging phase, there are significant variations in air pressure, temperature and mass flow rate resulting in low turbine efficiency. This research aims to improve the expansion process of the small scale D-CAES system through optimization of a small scale axial turbine. A small scale axial air turbine has been developed using 1D Meanline approach and CFD simulation using ANSYS CFX 16.2. For improving the turbine efficiency, different optimization approaches like single and multi-operating point optimization have been performed. The turbine blade profiles for both stator and rotor have been optimized for minimum losses and maximum power output based on 3D CFD modelling and Multi Objective Genetic Algorithm (MOGA) optimization for single and multi-operating points. Using multi-operating point optimization, the maximum turbine efficiency of 82.767 % was achieved at the design point and this approach improved the overall efficiency of D-CAES system by 8.07% for a range of inlet mass flow rate indicating the potential of this optimization approach in turbine design development.

A prototype of a miniaturized Clark type electrochemical oxygen sensor integrated with a 3D printed in vitro cell culturing platform is designed and developed for the purpose of monitoring the cellular oxygen consumption by the solution flowing through the cultured cells on the platform. Oxygen respiration indicates a cell's metabolic activity, so by measuring a chemical's oxygen content as it passes through a cell chamber, we can measure that chemical's potential effectiveness. This miniature micro sensor is designed and fabricated on a printed circuit board for the first time and integrated with a solid electrolyte membrane and 3D printed cell culturing platform to ensure robustness, low manufacturing cost and good electrical conductivity for sensing. Hence the sensor is aimed at enabling the pharmaceutical industry to rapidly test chemical products on animal and cancer cells; and has been designed to be low cost and suitable for mass production. The presented oxygen sensor configuration consists of two identical series of working, reference and counter microelectrodes. The solid polymer electrolyte membrane, Nafion (perfluorosulfunic acid membrane, DuPont Company) removed requirement for extra humidification and increased the shelf life of the sensor. The sensitivity of the oxygen sensor was tested in different oxygen concentration in gas and liquid states and was calibrated with measurements from a Portable Multi-Gas analyzer and a dissolved oxygen analyzer. The prototype can detect the small changes in oxygen concentration in the range of 0 to 5 μA current and has a response time of less than 5 seconds.

This research work focused on evaluations of improving the acceleration, cold start transient performances and emissions in a common rail direct injection (CRDI) turbocharged diesel engine. The temperature impacts on the engine emissions were investigated at ambient temperatures ranging between -7 and 20°C. The results show that the highest specific gaseous and particulate emissions are produced at the earlier stage of the NEDC. The particulates emitted at extremely high AFR conditions are more dominant compared to those that are caused by the turbo-lag problem over the NEDC. Both the fuel and engine oil contribute as main carbon sources to produce the SVOC particulate emissions from the engine combustion. A controlled intake air thermal heating system was implemented to improve the engine performances at cold ambient conditions. By using the thermal heating system, the engine efficiency during the first UDC can be improved by up to 1.46. By using high blending biodiesel fuels, the transient emission spikes can be significantly eliminated. The cumulative PN and THC emissions of biodiesel can be reduced by up to 75% and 50% respectively. An incremental transient EGR strategy was evaluated to improve the instantaneous particulate emission performance during acceleration conditions. With the improvement of the turbocharger performance and boosted intake fresh air mass flow, the novel strategy resulted in a reduced fuel injection quantity and improved combustion.

This work aims to investigate the performance of a new design for CPV/T system using 3D flat sided (3D V-trough) concentrators named squared (SAC), Hexagonal (HAC), Octagonal (OAC) and Circular (CAC) inlet and exit Aperture concentrators, with an effective cooling facility that keeps PV temperature within the Normal operating range. Novel mathematical optical models were generated, to the HAC and OAC geometries and validated using OPTISORKS software, to calculate the geometrical concentration ratio (GCR) and actual concentration ratio (ACR) by the inlet aperture area (A_in) a function of aperture width (W_in) and number of reflections (n), and material reflectivity (p) and at any concentrator side angle (Ψ), consequently the optical performance. Results showed that the optimum concentrator side angels for GCR of 2, 4, 6, 8 and 10 are 35°, 30°, 20°, 20° and 15°, respectively for all investigated geometries. Also COMSOL Multiphysics software was used for thermal modelling. Optical, thermal and electrical investigation results highlight that the designed CPV/T system is beneficial enough and feasible to be used in generating electrical and thermal powers for domestic use, as one useful package of energy with high output compared with the flat PV modules which generate only electrical power.

Compound Parabolic Collector (CPC) has numerous advantages such as high optical efficiency and wide applications. This thesis describes experimental and theoretical investigations of the effects of solar radiation available, design and orientation on different configurations of low concentration CPCs for Kano, Nigeria. Two solar radiation models were developed for characterizing solar radiation for regions in the northern hemisphere like Kano. Results showed that tilting the collector to the monthly optimum angle gives the maximum radiation obtainable in each month with highest increase of 28.6 and 24.8% in December and January respectively. For seasonal tilt; the best angles were 27.05° (October to March) and 0° (April to September) while for fixed collector, tilting at 12.05° (latitude) provides the highest performance. Using advanced ray tracing technique, detailed investigations of the effects of acceptance angle, receiver radius, truncation, etc. were carried out on the CPC performance. While with the truncation of 70%, results showed that compound parabolic collector can achieve daily average optical efficiencies of 86.2% and 75.4% for acceptance angles of 60° and 40° respectively. The performance of the thermosyphon (receiver) was investigated both experimentally and numerically. Using an in house solar simulator developed in this work, the performance of the developed CPC fitted with thermosyphon was experimentally investigated. Results showed that the CPC can function well with thermosyphon inclination angle up to 40° where it gives efficiency between 76% and 66%. The outcome of this work shows the potential of using this developed system in Kano environment for cooling applications.

Biodiesels have been proved to reduce the smoke and THC emissions by many researchers. The demands of biodiesel are increasing all over the world. Various feedstocks of biodiesel have been used in different countries and regions. The blend ratio of biodiesel in petrol station is also varies. Therefore, more calibration works have been done for the car manufacturers. In first part this research, the combustion characteristics and emissions of using biodiesels from different feedstocks with different blend ratio was studied by experimental works. Statistical analysis indicated the correlation between emissions and fuel properties. Then, a smoke index, containing Reynolds Number of fuel spray, cetane number and gross heat value of combustion, was created and showed a significant linear relationship with the smoke emissions. The effects of engine loads and EGR rates on the relationship were also discussed. The second part of this research was focused on the cold start with using biodiesel blends. The tests were conducted in a wide range of the temperatures (from -20°C to 90°C). Results showed that the methyl ester biodiesel reduced the PM during the acceleration period of the start at 20°C conditions. As ambient temperature decreased, using of biodiesel shows an increased emissions of PM and THC. The chemical compositions of particle emissions with using biodiesel blends at cold start were identified by a 20-GC/MS and the results also confirmed this trend.

The primary focus of this thesis is to determine the best methods for controlling the interpolation of NURBS curves and surfaces. The various factors that affect the quality of the interpolant are described, and existing methods for controlling them are reviewed. Improved methods are presented for calculating the parameter values, derivative magnitudes, data point spacing and twist vectors, with the aim of producing high quality interpolants with minimal data requirements. A new technique for obtaining the parameter values and derivative magnitudes is evaluated, which constructs a C\(^1\) cubic spline with orthogonal first and second derivatives at specified parametric locations. When this data is used to create a C\(^2\) spline, the resulting interpolant is superior to those constructed using existing parameterisation and derivative magnitude estimation methods. Consideration is given to the spacing of data points, which has a significant impact on the quality of the interpolant. Existing methods are shown to produce poor results with curves that are not circles. Three new methods are proposed that significantly reduce the positional error between the interpolant and original geometry. For constrained surface interpolation, twist vectors must be estimated. A method is proposed that builds on the Adini method, and is shown to have improved error characteristics. In numerical tests, the new method consistently outperforms Adini. Interpolated surfaces are often required to join together smoothly along their boundaries. The constraints for joining surfaces with parametric and geometric continuity are discussed, and the problem of joining \(N\) patches to form an \(N\)-sided region is considered. It is shown that regions with odd \(N\) can be joined with G\(^1\) continuity, but those with even \(N\) or requiring G\(^2\) continuity can only be obtained for specific geometries.