The work presented involves the theoretical and experimental studies of the kinematic and dynamic effects of bearing clearance in linkage mechanisms. In the test mechanism developed a six-bar linkage, having a test plain bearing, is oscillated at amplitude of 17.5 mm within the frequency range 4-7 Hz. A transducer assembly is used to measure the impact accelerations which are related to clearance size, mass distribution, spring load and excitation configuration, ( the vibrators are independently phased ). The motion-analysis of the test mechanism including clearance at a bearing is described using Lagrangian mechanics. The behaviour of the system is obtained by solving the coupled time-dependent equations using Kutta-Merson integration procedure. The method proves to be lengthy in computation time and not easily applied in design. Further, it is shown that there is little difference, in a gross sense, between the results so found and results obtained assuming no bearing clearance. An empirical formula relating the three parameters, clearance size, the rate of change of contact position and the corresponding minimum reaction force is derived from the no-clearance analysis. The. variation of this empirical relationship with excitation frequency is found to be similar to that obtained for the experimental impact levels. Thus it may be used to describe the impact accelerations and its numerical significance as a design criterion is suggested. The experimental work also demonstrates that the pattern of the impact levels remains unchanged when the bearing is oil film lubricated. Some simple design guides using the empirical relationship on a four-bar chain are suggested and general application from a practical point of view is discussed.

Accurate and repeatable heat-transfer data have been obtained for filmwise condensation from pure vapours (steam and Refrigerant 113) and vapour-gas (steam-air, steam-hydrogen, Refrigerant 1 13-air and Refrigerant 113- hydrogen) mixtures flowing vertically downward over single horizontal tubes. The tube surface could be viewed to ensure that the filmwise mode of condensation prevailed throughout all tests. Two copper tubes having diameters 12.5 mm and 25.25 mm were used. Surface temperatures at four positions were obtained from thermocouples embedded in the tube wall. The heat flux was obtained from coolant measurements which were checked against values obtained by condensate collection. The vapour mass flow rate was obtained from the electrical power input to the boiler. (The mass flow rate determination incorporated a correction for relatively small 'thermal losses' to the environment which were established by preliminary measurements in which all the vapour supplied to the test section was condensed and. collected. Non-condensing gases could be supplied continuously via variable-aperture float-type flowmetera to the boiler. The working length (r11O mm) of the condenser tube was located, centrally in the cylindrical test section (152.4 mm). The vapour Reynolds number (based on the teat section diameter) was generally greater than 2000. The mean vapour approach velocity over the working length was determined on the basis of a 'seventh power profile' in conjunction with the measured flow rate. The approximate ranges of the variables used were:- pressure (4 - 124 kpa), heat flux (12 - 466 kW/m2 ), vapour velocit' (0.3 - 26 n/a), gas mole (mass) fraction (o.i % (0.02 %) - 35 % (32 %)). The vapour-gas combinations were chosen to give a wide range of Schmidt number (about 0.05 - 0.5). For pure vapoura, the results are in overall agreement with earlier data (mostly steam) at moderate approach velocities. While discrepancies exist at higher velocities, both the present and earlier results show satisfactory agreement with theory at low and moderate velocities. The vapour-gas data are in good agreement with the limited earlier measurements (steam-air only) and with theory. In particular, the theoretically predicted Schmidt number dependence was clearly established.

<p> This thesis presents the design, analysis and optimization of a MEMS capacitive temperature sensor. The capacitive sensors are utilized in a wide range of applications from industrial and automotive applications to biomedical and food processing. A capacitive sensor has two conductive electrodes and its working principle depends on the change in the position of the electrodes or their effective area, which ultimately results in a change in the capacitance of the device. This thesis describes the modeling and the simulation results of a capacitive temperature sensor with a set of bimorph beams working as thermal actuators. The thermal actuator creates out-of-plane displacements and changes the distance between the electrodes as the ambient temperature changes. The presented bimorph capacitive temperature sensor consists of two bilayer silicon-gold beams and two capacitive electrodes, one of them is fixed to the substrate and the second one is connected to the beams. Different beam sizes and electrode shapes are designed and simulated and the characteristics capacitance-temperature (<i>C-T</i>) response of the sensor is obtained. The goal of this work is to modify and optimize the sensor geometry such that the <i>C-T</i> response is more linear, providing nearly constant sensitivity. ANSYS mechanical APDL is used as the finite element software for simulation and optimization of the sensor design, and coupled-field multiphysics solver is utilized to solve the electrostatic and structural domains. The simulation results show that for a given fabrication process, where the thickness of the structural and sacrificial layers in fabrication process is fixed, it is possible to modify the dimensions and geometry of the sensor such that a <i>C-T</i> response with high linearity is obtained. </p><p>

<p> This research presents new methods to apply safety standards to Detect and Avoid (DAA) functions for Unmanned Aircraft Systems (UAS), using maneuvering target tracking and encounter models. </p><p> Previous DAA research methods focused on predefined, linear encounter generation. The new estimation and prediction methods in this research are based on the target tracking of maneuvering intruders using Multiple Model Adaptive Estimation and a realistic random encounter generation based on an established encounter model. </p><p> When tracking maneuvering intruders there is limited knowledge of changes in intruder behavior beyond the current measurement. The standard Kalman filter (KF) with a single motion model is limited in performance for such problems due to ineffective responses as the target maneuvers. In these cases, state estimation can be improved using MMAE. It is assumed that the current active dynamic model is one of a discrete set of models, each of which is the basis for a separate filter. These filters run in parallel to estimate the states of targets with changing dynamics. </p><p> In practical applications of multiple model systems, one of the most popular algorithms for the MMAE is the Interacting Multiple Model (IMM) estimator. In the IMM, the regime switching is modeled by a finite state homogeneous Markov Chain. This is represented by a transition probability matrix characterizing the mode transitions. A Markov Chain is a stochastic model describing a sequence of possible events in which the probability of each event depends only on the previous event. </p><p> This research uses the hazard states estimates (which are derived from DAA standards) to analyze the IMM performance, and then presents a new method to predict the hazard states. To reduce the prediction error, this new method accounts for maneuvering intruders. The new prediction method uses the prediction phase in the IMM algorithm to predict the future intruder aircraft states based on the current and past sensor measurements. </p><p> The estimation and prediction methods described in this thesis can help ensure safe encounters between UAS and manned aircraft in the National Airspace System through improvement of the trajectory estimation used to inform the DAA sensor certification process.</p><p>

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.