Modern manufacturing processes require better quality control of the manufactured products at a faster rate, for achieving good throughput. This is increasing the need for process-oriented precision metrology capable of providing faster inspection and yielding valuable feedback to the manufacturing system for quality control of the manufactured products. Over the past twenty years optical sensors have emerged as a preferred method for the measurement applications in manufacturing automation, owing to some inherent advantages, such as high speed, high resolution, non-contact operation, and low cost. Improved online optical sensors for surface measurement would enable incorporating measuring systems into production processes and machines, improving the production performance and the quality of products, which is highly desired in many high/ultraprecision manufacturing applications. This thesis presents a novel spatially dispersed short coherence interferometry (SDSCI) sensor system for online surface measurement applications on the nanoscale. The SDSCI sensor system uses a low-cost broadband super-luminescent diode (SLD) with an emission bandwidth of 25 nm. Two measurement methods, phase shifting interferometry and Fourier transform for surface profile measurements, have been investigated in this study. The metrology sensor system incorporated the Michelson interferometer configuration with an optical probe in the measurement arm, while the reference arm had a mirror with a piezo-electric transducer. The technique involves surface scanning by spatially dispersing the broadband light using a reflective grating and a scan lens, and recording the resulting interferogram by using a high-speed spectrometer. The first measurement method involved investigations of implementation of phase shifting interferometry and the Carré algorithm for phase retrieval from the measured phase-shifted interferograms for profile measurements. Standard diamond turned multi-stepped and NPL artefact samples with 550-nm and 100-nm-high steps, respectively, were measured and confirmed the capability of the measurement sensor. The measurement speed of this technique was limited by the spectrometer speed and by the piezo-electric transducer movement. The optimised system has a measurement time of 1s. The second method was then investigated based on the Fourier transform profilometry technique for further increasing the measurement speed of the sensor device, as it required a single-shot interferogram, alleviating the need of any phase shifting. With increased measurement speed, this technique further reduced the problem of environmental noise inherent to all interferometer-based systems. Similar artefacts were measured by using this technique for evaluating its applicability for surface profile measurements. Once the sensor system was optimised and calibrated, the resulting open-space system could be further miniaturised into a compact sensor system by using optical fibres with a remote probe connected via a fibre link for use in embedded metrology applications. This method will be very beneficial in online inspection of samples in rollto-roll manufacturing processes, where the measurand is constantly moving. An example of such a measurement challenge is detection of defects on vapour barrier films formed by depositing an aluminium oxide layer several tens of nanometres thick on a flexible polymer substrate. Effective detection and characterisation of defects in this layer requires a single-shot approach with nanometre-scale vertical resolution.

This thesis concerns numerical investigations of the combustion behaviour of various combustion regimes. The simulations are based on modelling the flow of the fuels in the combustion devices. Computational fluid dynamics (CFD) modelling and analysis were used in three different works. FLUENT software, which is based on the finite volume method, is used to carry out all the simulations. Firstly, numerical simulations were carried out to investigate the turbulent non-premixed combustion of a mixture of methane (CH4) 90% and nitrogen (N2) 10%, on volume basis, inside an axis-symmetric cylindrical chamber (base case). The objective is to investigate the turbulent flow, flame propagation, temperature and species concentration and evaluate the effects of different reduced reaction mechanisms of methane and the influence of various turbulence models on them. The turbulent combustion inside the chamber occurs under a condition for which the equivalence ratio (ɸ) of 1.04 is used. Instead of using fully detailed chemical kinetics schemes and to reduce the computational costs, four global reduced chemical kinetics mechanisms are employed in the combustion model and they are named as (M-I, M-II, M-III and M-IV). The simulations, in which M-I is used, are performed by Renolds-Averaged Navier Stokes (RANS) approach with the three two-equation k-ϵ closures (standard, realizable and RNG) employed to model the turbulent flow. Concerning the chemistry-turbulence interaction, the finite-rate/eddy-dissipation model (FR/ED) is used. The first two of the above kinetics schemes are two-step reaction mechanisms and the other two are first-step and five-step reaction mechanisms, respectively. The latter one is used to assess the capability of FR/ED model for modeling such a mechanism. The influence of thermal radiation is also investigated by means of P-1 model. The standard k-ϵ model and realizable k-ϵ model are also modified and used in the course of simulations. Moreover, the reaction mechanism (M-II) is optimized to see its effects on the combustion process. The results are compared with the experimental data and gave good agreement. It is found that the best results are generally obtained using the modified standard k-ϵ model. Moreover, the simulation results using the realizable turbulence model are found to have large discrepancies compared to the experimental data. In comparison with the experimental data, the optimization of M-II (Em = 1.6x108 J/kmol) is found to have good results in terms of temperature. Increasing the dilution of the fuel by N2 is investigated. Four cases, CH4 (85, 80, 75 and 100%) on volume basis, are performed. The latter one concerns the combustion of pure methane. The results are compared with the base case and found that the base case is the best compromise to obtain the highest temperature in inside the chamber. Secondly, an axis-symmetric combustion model based on the Euler-Lagrange approach was formulated to model the combustion of pulverized bituminous coal. Three cases with three different char oxidation models are presented. In case1 and case 2, the diffusion and kinetic/diffusion global char models are used, respectively. Whereas, to model char oxidation in case 3, the multi-surface reactions model is used. The volatiles released during the devolatilization stage, which is modelled using a single kinetic rate model, are treated as one species and its combustion is modelled using the FR/ED model. The predicted results have good agreement with the available experimental data and the best predictions are obtained from case 3. The results showed that the combustion inside the reactor was affected by the particulate size. It is found that the burnout of the particle with the diameter of 16 μm at the exit of the furnace is 100%. Whereas, the burnout of the particles with diameters of 84, 154, 222, 291 μm is approximately 86, 75, 35, 33, 29 %, respectively. A number of simulations were carried out to find the best values of parameters suitable for predicting NOx pollutants. The chemical formation and reduction rates of NO are calculated by post-processing data obtained from the previously reacting flow simulations. This method is computationally efficient. For volatile-N is assumed that the nitrogen is released via the intermediates HCN and NH3. For char-N path way, it is assumed that all the nitrogen is released via the intermediate HCN. It is found that the assumption of the partition of volatile-N by 52% HCN, 10% NH3 and 38% NO has the best agreement with the experiment data. The influence of different operating parameters on the combustion process and NOx formation was investigated as well. For the same operating conditions and the same particles size distribution, the combustion of pulverised biomass alone, represented by straw, was investigated followed by the investigation of its firing with coal. The former one show a promising results under such operating conditions. It is found that the temperature distribution when burning straw particles is nearly the same as that obtained from burning coal because all the saw particles are completely burned out inside the furnace when compared with the coal particles. The NOx model, in which the ratio of HCN to NH3 is suggested to be for the partitioning of volatile-N, shows that NO formation is reduced by approximately 20% for case I and 26% for case II at the exit of the furnace when compared to coal. For the latter one the results of co-firing blends of coal with 10, 20, 30 and 40% share of biomass are presented and show the influence of co-firing on the combustion process. Co-firing of straw with coal enhances the combustion behaviour and increases the burnout of coal particles compared to that of coal firing only. It is seen that the burnout of the particles with sizes 84, 154 and 222 μm is remarkably increased. On the other hand, the burnout of the other two particles (291 μm and 360 μm) does not show a great change. The share of 10% of straw shows the highest temperature. Thirdly, Two-phase computational modelling based on the Euler–Euler was developed to investigate the heterogeneous combustion processes of carbon particles inside a newly designed combustion chamber. A transient simulation was carried out for a small amount of carbon powder situated in a cup which was located at the centre of the combustion chamber. A heat source was provided to initiate the combustion with the air supplied by three injection nozzles. The combustion simulations are performed for particle sizes with different diameters (0.5mm, 1mm, 1.5mm, 2mm, 2.5mm and 3mm). The particle of 1mm diameter is assigned to the baseline case. The results show that the combustion is sustained in the chamber, as evidenced by the flame temperature. It is shown that, up to a time of 0.55 s, the higher temperature was gained from the case of carbon particles with the diameter of 3 mm and burning the carbon particles with a diameter of 0.5 mm produces lower temperature. This may be attributed to the residence time of the carbon particles and the design of the burner. The larger particles stay longer than the smaller ones inside the chamber. This may due to the reason that the smaller particles follow the streamlines of the continuous phase and increasing the particle size leads to that the larger particles may deviate from the streamlines of the continuous phase and their slip velocity may increase resulting in enhancing convective transports of heat and species concentrations. The influence of the chamber design was also investigated. The height of the chamber is doubled. With the same operating conditions, up to a time of approximately 0.55 s, it is found that burning carbon particles in the doubled height chamber produces higher temperature than the baseline case (particle diameter 1 mm) and after this time the opposite takes place. Most of the other cases do so.

Visible light communication is a developing technology making use of light-emitting diodes (LEDs) and laser diodes in the visible spectrum for communication purposes. This thesis looks at the use of gallium nitride (GaN) devices for high speed measurements in free space, through fibre and underwater. Micro-pixellated LEDs (micro-LEDs) have been used as a source for these measurements and the different ways to drive these devices is explored. LEDs are limited in how fast they can be driven and therefore laser diodes are also considered for these high speed measurements. The frequency responses of such devices are measured and data transmission experiments are conducted. However, these devices can be used for more than just free-space communication. Laser diodes are much more powerful than their LED counterparts and can be modulated much faster making them ideal for fibre communications and underwater communications, where eye-safety is not an issue. By using these devices, a study of step-index plastic optical fibre (SI-POF) and multi-core fibre is carried out, analysing their dispersion properties and transmission characteristics. Further high speed measurements were conducted under the water as the need to communicate with unmanned vehicles under the ocean continues to be an important issue. Many security and defence companies and oil and gas industries are interested in this technology for that purpose, as the current setup is complex, expensive and limited in bandwidth. High modulation bandwidths and high data transmission rates are achieved, with some of the leading results in the field presented here. These results highlight the importance of the topic of visible light communication and show the attractiveness of using these visible GaN devices for this purpose.

Analytical, computational and experimental studies were carried out to investigate heat transfer and fluid flow in micro-channel absorber plates for compact (thin and light-weight) solar thermal collectors. The main objective of the work was to study different design and/or operating scenarios as well as study the significance of various micro-scaling effects. Analytical investigation showed that, under similar conditions, the proposed design yields a much higher fin efficiency, F and collector efficiency factor, F’ compared with the conventional solar collector design. An analytical model combining convective heat transfer in the collector fluid with axial conduction in the metal plate was developed. The predicted plate temperature profiles from the analytical model were in close agreement with the measured profiles. The model further showed that axial thermal conduction can significantly alter the plate temperature profile. Experiments were designed to represent real life operation of the proposed system. A CFD study, using the same design and operating parameters, produced results comparable with experiments. This numerical simulation also gave further insight into the heat transfer and fluid flow patterns in the micro-channel plate. The effect of channel cross section geometry was studied. The Nusselt number was observed to increase as the aspect ratio approached unity. Measured friction factors were similar in trend to the predictions for rectangular channels, although the overall rise in fluid temperature resulted in slightly lower friction factors. Thermal performance reduced slightly with increase in hydraulic diameter. The significance of various scaling effects was also investigated experimentally and numerically. Most of the typical scaling effects such as viscous dissipation and entrance effects were found to be insignificant however, conjugate heat transfer, surface boundary condition, surface finish and measurement uncertainties could be significant. The results showed a Reynolds number dependent Nusselt number which has been attributed to axial thermal conduction. It was also observed that only three walls were transferring heat; the walls of heat transfer had a uniform peripheral temperature while the heat flux varied peripherally. The closest simplified thermal boundary condition to represent heat transfer in these channels is the H1 with three (3) walls transferring heat. Increased surface roughness (obtained by using an etching technique to create the channels) was found to have a detrimental effect on heat transfer. The results showed that thermal improvement can be achieved by increasing the fluid velocity; however, pumping the thermal fluid above a pump power per plate area of 0.3 W/m2 resulted in marginal improvement. In practice, optimum microchannel geometry in plates should be sized based on fluid properties and operating conditions. The micro-channels should also have thin walls to minimise the effects of conjugate heat transfer. A Photovoltaic pump should be installed alongside the collector in order to provide pumping power required and minimise the overall fluid temperature rise. The results are beneficial for the design of micro-channel absorber plates for low heat flux operation up to 1000W/m2.

This empirical study investigates the factors influencing Nigerians’ trust and adoption of mobile banking technology; using an integrative model. Research was conducted using a questionnaire developed and distributed in Nigeria. Out of 2256 returned questionnaires, 1725 were deemed to have been completed and hence usable. The data was analysed using confirmatory factor analysis and the results showed that confidentiality, integrity, authentication, access control, best business practices and non-repudiation significantly influenced technology trust with availability showing unsatisfactory values for consideration. In addition, technology trust showed a direct significant influence on perceived ease of use and usefulness. Technology trust also showed an indirect influence on intention to use through its impact on perceived usefulness and perceived ease of use. Also, perceived ease of use and perceived usefulness showed significant influence on consumer’s intention to adopt the technology. As a result of increased understanding of customer trust and adoption trends in Nigeria, these findings have important theoretical implications for researchers with interests in technology acceptance trends and the role of external factors, such as trust, in user adoption of technology. Such implications include the provision of empirical data, which highlights the role technology trust, demographic segmentations, perceived ease of use and perceived usefulness play in mobile banking adoption in Nigeria. In addition, the successful completion of this study provides justification for the use of this research’s model as a suitable framework for investigating user adoption of technology.

Multiphase flow can be defined as the simultaneous flow of a stream of two or more phases. Solids-in-water flow is a multiphase flows where solids and liquid are both present. Due to the density differences of the two phases, the results for such flow is often to have non-uniform profiles of the local volume fraction and local axial velocity for both phases in the flow cross-section. These non-uniform profiles are clearly noticeable in solids-in-water stratified flow with moving bed for inclined and horizontal pipelines. However in many industrial applications, such as oil and gas industry, food industry and mining industry, multiphase flows also exist and it is essentially important to determine the phase concentration and velocity distributions in through the pipe cross-section in order to be able to estimate the accurately the volumetric flow rate for each phase. This thesis describe the development of a novel non-intrusive flow meter that can be used for measuring the local volume fraction distribution and local axial velocity distributions of the continuous and discontinuous phases in highly non-uniform multiphase flows for which the continuous phase is electrically conducting and the discontinuous phase is an insulator. The developed flow meter is based on combining two measurement techniques: the Impedance cross correlation ICC technique and the electromagnetic velocity profiler EVP technique. Impedance cross correlation ICC is a non-invasive technique used to measure the local volume fraction distributions for both phases and the local velocity distribution for the dispersed phase over the pipe cross-section, whilst the electromagnetic velocity profiler EVP technique is used to v measure the local axial velocity profile of the continuous phase through the pipe cross-section. By using these profiles the volumetric flow rates of both phases can be calculated. A number of experiments were carried out in solid-in-water flow in the University of Huddersfield solids-in-water flow loop which has an 80 mm ID and an approximately 3m long working section. ICC and EVP systems were mounted at 1.6 m from the working section inlet which was inclined at 0 and 30 degree to the vertical. The obtained result for the flow parameters including phase volume fraction and velocity profiles and volumetric flow rates, have been compared with reference measurements and error sources of difference with their reference measurements have been identified and investigated.

Complex design specifications and tighter tolerances are increasingly required in modern engineering applications, either for functional or aesthetic demands. Multiple sensors are therefore exploited to achieve both holistic measurement information and improved reliability or reduced uncertainty of measurement data. Multi-sensor integration systems can combine data from several information sources (sensors) into a common representational format in order that the measurement evaluation can benefit from all available sensor information and data. This means a multi-sensor system is able to provide more efficient solutions and better performances than a single sensor based system. This thesis develops a compensation approach for reverse engineering applications based on the hybrid tactile-optical multi-sensor system. In the multi-sensor integration system, each individual sensor should be configured to its optimum for satisfactory measurement results. All the data measured from different equipment have to be precisely integrated into a common coordinate system. To solve this problem, this thesis proposes an accurate and flexible method to unify the coordinates of optical and tactile sensors for reverse engineering. A sphere-plate artefact with nine spheres is created and a set of routines are developed for data integration of a multi-sensor system. Experimental results prove that this novel centroid approach is more accurate than the traditional method. Thus, data sampled by different measuring devices, irrespective of their location can be accurately unified. This thesis describes a competitive integration for reverse engineering applications where the point cloud data scanned by the fast optical sensor is compensated and corrected by the slower, but more accurate tactile probe measurement to improve its overall accuracy. A new competitive approach for rapid and accurate reverse engineering of geometric features from multi-sensor systems based on a geometric algebra approach is proposed and a set of programs based on the MATLAB platform has been generated for the verification of the proposed method. After data fusion, the measurement efficiency is improved 90% in comparison to the tactile method and the accuracy of the reconstructed geometric model is improved from 45 micrometres to 7 micrometres in comparison to the optical method, which are validated by case study.

Civilisation has depended on welded structures to facilitate production and improve the quality of life. Welds are used to create infrastructure upon which we rely, such as transportation, oil and gas piping, shipbuilding, bridges and buildings, and to produce the equipment that makes all of this happen. In short, the joining of two metals through welding has immensely contributed to our society. A critical factor in the strength of welded joints is the geometry of the joints, and for this reason a robust optimisation of geometrical parameters of welded joints has been conducted in order to establish the optimum and most robust design in the presence of variation amongst geometrical parameters. A parametric finite element analysis, using Python script, has been performed with the objective to investigate the effect of the welded joint parameters on the stress concentration factors under tensile and bending load. The results indicate that the parametric model, which is generated by Python script, can be used in a wide range of welded geometry, and has the capacity to reduce the time of computation. Additionally, an experimental study, including the geometrical identification of the welded joints, tensile test, hardness test and fatigue, has also been performed. In order to select the best optimisation algorithms, different optimisation algorithms and performance metrics with various types of problem were examined in this study. The results from this part show the accuracy of Circumscription Metric (CM) in comparison to Pair wise Metric (PW) - which is used widely in optimisation studies. Furthermore, the results show that the Fast Multi-objective Optimisation Algorithm (FMOGA-II) outperformed other optimisation algorithms used during this study. In this study, a new methodology for selecting the most robust designs from within the Pareto set has been developed. Finally, a traditional and robust optimisation of a butt welded joint has been performed by establishing a link between an optimisation software package and parametric finite element, the results of which show the ability of this approach to extract the robust optimal designs from the Pareto front.

The objective of this thesis is to introduce a new method for identifying and detecting Intellectual Property (IP) in digital devices. The technology operates by inserting a small, low powered digital tag into a digital design; the tag is detected using temperature as a novel covert communications channel. The IP detection technology is a non-destructive, simple to use method which quickly detects the IP via the digital device package and thus requires no prior knowledge of the system. The method is intended to be used alongside existing IP protection methods. This thesis focuses on four areas: proving that temperature can be used to communicate information by varying both the internal and external temperature of an electronic device; the development of an active tag using a range of internal digital heat generators; the design of a passive tag, using an internal heat sensor and an external heat source; the invention of a True Random Number Generator (TRNG) using the digital properties of a Field Programmable Gate Array (FPGA). This research was sponsored by Algotronix, a company which develops security IP Cores for use in FPGAs. Both the active tag and TRNG were incorporated into Algotronix’ award winning DesignTag product.

The rapidly expanding civil aerospace sector is subjected to ever increasing pressure to be both sustainable and competitive. The research reported in the current thesis forms a part of the significant R&D effort of Rolls-Royce in response to this pressure. A broad based approach is taken to evaluating compressor blade surface finish with the objective of improving manufacturing and operating efficiency. Technical developments made as part of the current work is also intended to support future research in this important field. Compressor blade surface finish is emulated in the lab to detail its topographical development through the critical final polishing stage of processing. Based on existing surface standards a new characteristic developmental pattern and nomenclature is described for this finishing process. In addition, ‘edge shadowing’ a novel surface texture distribution is reported showing mass finishing to be non-uniform over a flat surface. The surface texture of exemplar ’as manufactured’ compressor blades is assessed and a protocol for areal parametric characterisation is developed. The protocol includes consideration of; surface texture homogeneity, local & global sample weighting, sampling efficiency, and key characteristic areal parameters, with their specification levels and confidence intervals. This detailed examination of mass finishing and the surface texture it produces will help improve process control and optimise economy. To improve the ongoing assessment of compressor performance degradation in service, a series of recovered compressor blades are characterised. Predominantly automated techniques are developed to assess compressor blade side and leading edge character. Key trends in surface topography on individual blade surface regions are reported along with broader degradation trends throughout the compressor. Leading edges are shown to be characteristically prone to greater degradation and levels of surface roughness, though elevated leading edge roughness is better correlated with deposits than with erosion. Proper analysis of aerodynamic losses due to aerofoil surface roughness requires the use of techniques with conflicting requirements. Thus in the current context the replication of metallic test aerofoils in thermally insulating resin is required. A method for this replication and its validation are presented. To investigate the underlying mechanisms of drag loss due to surface roughness a series of rough test aerofoil surfaces were parametrically characterised and wind tunnel tested. The well-established but incomplete correlation between drag loss and mean surface roughness amplitude (Sa) is then refined with other selected parameters that more fully represent surface topography.