The piston-cylinder liner interface comprises more than half of the total engine rubbing friction. With current demand being for internal combustion engines with better fuel economy, lower exhaust emissions and higher performance, reducing this form of friction is the subject of much study. The research reported in this thesis is concerned with the development of an existing floating liner rig to measure the friction in this region. The performance features of the modified setup have also been assessed. Parametric studies have been undertaken with the modified setup to identify the potential means of friction reduction. Modifications undertaken in the sealing method and driveline assembly has facilitated friction measurement at higher gas loading of up to 80 barg. The modified sealing assembly with a sealing ring overcame the problem of arbitrary force interruption through irregular liner and seal contacts. Addition of five times higher inertia flywheel aided the motor to support the rig with adequate torque during high gas loading operations. Calibrations have been performed at each different build of piston-liner combination to reduce build to build variability in measurement. Experimental studies have been undertaken to assess the friction characteristics for different factors such as operating pressure, temperature and speed, lubricant oil formulation, piston-liner clearance, piston material etc. Tests have been undertaken at a range of operating conditions; peak pressure of 0 to 80 barg, speed of 1000 to 2000 rpm and average mid-liner temperature of 40 to 90 ˚C. Peak cylinder pressure has been observed to be dominating the friction followed by temperature and speed. Friction spikes were observed near the top dead centre for pressurised operations; where normal load on the rings are highest in a cycle. Higher speed generally results in a higher total frictional loss. However at higher temperature and peak pressure, contrasting effect of speed on total friction has been reported. The study further identified that piston motion play important roles in determining mixed/boundary friction along with the local gas pressure, velocity and oil film temperature. Friction reductions have been obtained by using a lower viscosity oil and higher piston-liner clearance. Maximum friction reduction of 18% has been reported in this study by using SAE 0W-30 oil in place of SAE 5W-30. Diametric clearance of 80 μm obtained a maximum reduction of 12% compared to a lower clearance of 20 μm. The use of steel piston has shown potential in reducing friction over aluminium piston but the design and weight of piston played a dominant role in the frictional loss.

This research focuses on swarm-based optimisation algorithms, specifically the Bees Algorithm. The Bees Algorithm was inspired by the foraging behaviour of honey bees in nature. It employs a combination of exploration and exploitation to find the solutions of optimisation problems. This thesis presents three improved versions of the Bees Algorithm aimed at speeding up its operation and facilitating the location of the global optimum. For the first improvement, an algorithm referred to as the Nelder and Mead Bees Algorithm (NMBA) was developed to provide a guiding direction during the neighbourhood search stage. The second improved algorithm, named the recombination-based Bees Algorithm (rBA), is a variant of the Bees Algorithm that utilises a recombination operator between the exploited and abandoned sites to produce new candidates closer to optimal solutions. The third improved Bees Algorithm, called the guided global best Bees Algorithm (gBA), introduces a new neighbourhood shrinking strategy based on the best solution so far for a more effective exploitation search and develops a new bee recruitment mechanism to reduce the number of parameters. The proposed algorithms were tested on a set of unconstrained numerical functions and constrained mechanical engineering design problems. The performance of the algorithms was compared with the standard Bees Algorithm and other swarm based algorithms. The results showed that the improved Bees Algorithms performed better than the standard Bees Algorithm and other algorithms on most of the problems tested. Furthermore, the algorithms also involve no additional parameters and a reduction on the number of parameters as well.

The general aim of this study is to develop a 3-D FE model for multi-point forming dies using ABAQUS software and use this to study the effect of process parameters related to tool geometry such as radius of curvature of deformed parts, pin size, elastic cushion thickness and coefficient of friction. Doubly curved parts will be investigated in this research. The material properties for two blanks were determined for use as required parameters for the simulation analysis. Finite element models of the doubly curved forming process were developed and validated for two materials: DC05 steel sheet and 5251-0 aluminium sheet. The mesh sensitivity, reliability of the numerical model, suitable blank holder force, effect of gap distance between punch and blank holder on the thickness distribution, and the comer defect were studied. A parametric study was carried to investigate the effect of certain parameters on the deviation from target shape, wrinkling, and thickness variation. A test rig for the experimental work was designed and manufactured. In parallel, experiments with the forming of doubly curved parts were conducted to validate the simulation results. The numerical analysis results were compared with the experimental results and good agreement was generally found. The methodology developed in this research could help to build a reliable numerical model to predict the common defects in sheet forming using the multi-point forming process.

Surface treatments by applying laser processing have gained a significant attention due to the achievable surface properties along with the selectivity that cannot be realized with other methods. The focus of this research is on investigating and developing laser-based treatment methods, i.e. laser-induced surface oxidation, laser-induced oxygen reduction, and laser-induced periodic surface structures (LIPSS), to address the requirements of specific applications in optics, aesthetics, and anti-counterfeiting, e.g. colour marking and the fabrication of optical devices and diffraction holograms. A single spot oxidation method is proposed to control the size of the oxidation area and its thickness on titanium substrates. A pixel resolution down to the beam spot size with high special control is achieved. To produce diffraction optical devices on glass substrates a direct writing another method is proposed. Especially, the method is implemented and validated for fabricating two-level phase-type FZPs with a nanosecond laser by converting a titanium film on glass substrates into titanium dioxide patterns with a thickness controlled at nano scale. The flexibility and applicability of laser-induced oxidation is extended with a method for erasing colour marks selectively by employing a laser-induced oxygen reduction. Finally, a method for producing LIPSS patterns with varying orientations is developed and then validated for fabricating diffraction gratings on metallic surface.

Photoplethysmography (PPG) is a non-invasive photometric technique which measures changes in the volume of blood in the biological tissue. PPG is well-known for its application in pulse oximetry used for the continuous monitoring of arterial blood oxygen saturation (SpO2). Over the past decade, there has been a plethora of research in the field of PPG, with potential applications beyond pulse oximetry and heart rate monitoring. Such applications explore the utilisation of PPG for the assessment of various bio-markers relating to vascular mechanics, haemodynamics and many others. With the growing research interest in the field of PPG, a comprehensive understanding of the light-tissue interaction-based working principle underlying the technique is essential. This thesis is focussed on the investigation of the fundamental light-tissue interactions in PPG using the Monte Carlo method. Tissue models have been developed in this thesis which were characterised by the optical properties (e.g., wavelength- dependent coefficients of scattering and absorption etc.), the anatomical features (e.g., stratification and dimension of tissue layers and sublayers etc.), and the physiological parameters (water and blood content in tissue layers etc.). The Monte Carlo strategy was verified, and was initially implemented to model the light propagation through a monolayer perfused dermal tissue volume in a reflective mode PPG at the red and near-infrared wavelengths, usually used in pulse oximetry. Results illustrated the distribution of the scattering-absorption interaction events, and quantified the optical pathlength, penetration depth and detected reflectance with the variable sensor geometry (i.e., source-detector separation) and physiological states (i.e., the volume of blood and oxygen saturation) of the tissue. The monolayer model was also employed to produce the plot resembling the 'calibration curve' used in pulse oximetry. With the knowledge gained from the monolayer-model study, a similar investigation was performed on a heterogeneous tissue structure of a human finger which was executed in both reflective and transmissive geometrical settings. The calibration curves produced from the detected reflectance and transmittance exhibited a high correlation. The absorbances of red and near-infrared light by individual layers of the finger were quantified at systole and diastole. To the relative absorbance, the contributions of dermis and bone were the maximum and the minimum, respectively. The dependence of the optical pathlength on the source-detector separation and the operating wavelength was quantified by the Differential Pathlength Factor (DPF), which was assessed for the reflective mode PPG by simulating light propagation through a human forearm tissue volume. The DPF values were used in experimentally obtained PPG signal in order to determine the time-change in the concentration of oxyhaemoglobin and deoxyhaemoglobin. Cross-talk and absolute errors were calculated between the simulated and approximated DPFs. The results presented in the thesis contribute greatly to the understanding on PPG light-tissue interaction. Such knowledge could also greatly contribute to the development of the new generation PPG sensors for various applications.

This research aims to study in a comprehensive way a different power generation cryogenic energy storage cycles and effective strategies for developing an optimized design of small scale nitrogen axial turbines as the expanders for these cycles within the capacities that can be used for small/medium size buildings, rural, and remote off-grid communities. The hybrid open-closed Rankine cycle have been chosen as the case study for nitrogen turbine analysis for expansion ratios ranged from 1.5 to 3. New turbine design methodology has been developed which integrates one dimension preliminary design method (mean-line method) and three dimensional CFD simulations, and expe1imental validation testing. This turbine methodology was expanded to include developing optimization parametrization technique, a parametric study of four different blade configurations (lean, sweep, twist, and bow), and development of a novel dual stage non-repeated annular area small-scale axial nitrogen turbine. In order to validate the CFD simulation, the design methodology, and to investigate the effects of blade height on small-scale axial turbines performance, a test rig using compressed air was developed. Three manufactured axial turbines with different blade heights ( 4mm, 6mm, and 8mm) were manufactured and tested at various operating conditions.

Focusing on the author's research aspects, the intelligent optimization algorithm and advanced control methods of the diesel engine's air path have been proposed in this work. In addition, the simulation platform and the HIL test platform are established for research activities on engine optimization and control. In this thesis, it presents an intelligent transient calibration method using the chaos-enhanced accelerated particle swarm optimization (CAPSO) algorithm. It is a model-based optimization approach. The test results show that the proposed method could locate the global optimal results of the controller parameters within good speed under various working conditions. The engine dynamic response is improved and a measurable drop of engine fuel consumption is acquired. The model predictive control (MPC) is selected for the controllers of DLEGR and VGT in the air-path of a diesel engine. Two MPC-based controllers are developed in this work, they are categorized into linear MPC and nonlinear MPC. Compared with conventional PIO controller, the MPC-based controllers show better reference trajectory tracking performance. Besides, an improvement of the engine fuel economy is obtained. The HIL test indicates the two controllers could be implemented on the real engine.

This thesis investigates the feasibility of producing electricity and cooling simultaneously utilising low-grade heat sources by incorporating an expander within the adsorption cooling system or by integrating an Organic Rankine Cycle with water adsorption cooling system. Advanced physical adsorbent materials have been investigated for the first time to generate cooling and electricity simultaneously utilising CPO-27(Ni), MIL101(Cr), and AQSOA-Z02 and compared to commonly used Silica-gel. Two innovative configurations of water adsorption systems for cooling and electricity were investigated. In the first configuration, the two-bed basic adsorption cooling system (BACS) is improved by including an expander within the system. In the second configuration, the BACS and ORC cycle are integrated. Four different scenarios of systems integration based on the way of powering the ORC and the adsorption system were investigated. Also, detailed CFD simulations of small-scale radial inflow turbines are developed for both configurations. Also, a novel experimental facility is developed to integrate ORC with two-bed adsorption cooling system to validate the numerical models and proof the concept of producing power as well as cooling, where maximum specific cooling power of 252 W/kgads and specific power and of 162 W/kgads can be achieved with maximum deviation of less than 17%.

This research introduces two different methods that are Levy Flight and Hooke and Jeeves to the Bees Algorithm with the aim of improving the convergence speed and its robustness. Both methods are incorporated to the Bees Algorithm at neighbourhood search of the elite bees since that particular locations are the most promising area during optimisation process. Each Bees Algorithm and the newly incorporated method with thirteen different parameter settings are subjected to fifteen different benchmark test functions. These benchmark test functions are represented with different characteristics in terms of its differentiability, separability, scaleability, and modality. Bees Algorithm with Levy-flight method incorporated to the local search performs excellent result for 13 out of 15 functions against standard Bees Algorithm in terms of its success rate and convergence speed in which it is validated by the statistical T test. As a matter of fact, the new method indicates better robustness for 13 functions in terms of achieving good result for solving different types of optimisation problems. For the Bees Algorithm with Hooke and Jeeves method, the new approach reaches a relatively better performance compared with standard Bees Algorithm in which one parameter excels at reaching optimum solution for most of the test functions.

Electrochemical Jet Processing (EJP) techniques have been traditionally limited in application by the inherent geometric inflexibility and limited process precision in comparison to alternative processes. It has been stated that process resultant geometries are defined by the Gaussian in-jet energy distribution and the hydrodynamic stagnation region formed under a jet on an impinging surface. This thesis reports upon investigations and innovations designed to challenge these assumptions. EJP is an emergent manufacturing process with a unique capability of subtraction and deposition of metals within a common machine tool. EJP demonstrates advantages beyond traditional electrochemical machining and electrochemical deposition including a high degree of flexibility, simplistic and therefore low-cost plant, requiring no complex, high-cost tooling and no masking requirement to achieve high fidelity geometries. These process traits are attractive to industry but EJP has yet to find significant commercial use. Electromechanical and electrochemical innovations are presented here demonstrated by electrochemical jet machining (EJM) the subtractive mode of EJP, which allow modulation of the properties of the inter-electrode gap leading to a paradigm shift in the functionality, precision and application of EJP. Electromechanical innovations demonstrate that the Gaussian energy distribution can be modified through the articulation of the jet angle of address and modified jet nozzles to manipulate the in-jet resistance. The outcome being the capability to produce bespoke removal profiles with increased precision and flexibility of form alongside refined surface finishes. Electrochemical innovations demonstrate an increase in precision through reducing overcut and reducing the feature shoulder radius when using a modified electrolyte. When these electromechanical and electrochemical innovations are coupled together, the overcut traditionally seen to be twice the nozzle diameter is reduced by 99%. Therefore, features can be created at kerfs approaching the nozzle diameter. Alongside this, a bespoke research platform has been built and developed to exploit these findings and incorporate features such as the rotational head for constant profiling and multiplexing of electrolytes to enhance the flexibility of the process. Process enhancements developed through this thesis have allowed the manipulation of the in-jet energy density profile and dissociation of the dissolution region from hydrodynamic phenomena thus allowing surface structuring by EJP to be developed well beyond the state-of-the-art.