This thesis is concerned with the application of photon correlation velocimetry to the design of products which employ rotating components in fluids. Two examples are considered, viz. The development of turbines and compressors for power generation. The development of propulsor design for use on underwater powered vehicles. The former required the measurement of high speed gas flows (up to Mach 1.8) both within cascades and in a model turbine. The latter entailed tests on models in both a water tunnel and a wind tunnel with flow velocities of up to 15 meters per second and 50 meters per second respectively. In each case a 50 nanosecond digital correlator was used and the optical systems were designed to operate within constraints set by this, the nature of the expected flows, the optical access available and the information sought. In all three applications, a backscatter geometry had to be used. Laser Doppler velocimetry was employed in the propulsor design. However, since the upper Doppler frequency limit of the correlator was 10 Mz., the high speeds encountered in the turbine and compressor models necessitated the use of laser transit velocimetry. Details of the systems design, the optics and data reduction software are given. Some experimental results of measurements made within cascades and rotating components are presented and their significance concerning the velocimeters used are discussed. The chief conclusions which are drawn from the work are: In many flow configurations of practical interest in gas and steam turbines, transit velocimetry with photon correlation can be used to measure mean velocity to within 1% and turbulence intensity to within 1%. However, in some regions, particularly where the turbulence intensity exceeds approximately 15%, the results are not easy to interpret. Despite the low upper limit to Doppler frequency that can be managed by the 50 nanosecond correlator, its power in processing low-light-level and noisy signals enabled it to be used effectively with a Doppler velocimeter for the measurement of flows within propulsor blading both in a water tunnel and in a wind tunnel. When used with Doppler velocimetry, the inherent averaging mode of operation of the correlator permitted the measurement of mean velocity to within 1%. It also provided a measure of turbulence intensity, which was self consistent to within 2%, although the relationship between this and the standard deviation of velocity was ambiguous. Analysis of the properties of photon correlation in laser velocimetry indicated scope for future work in two directions. Firstly, photon correlation responds to uncertainties arising from particle and velocity biasing in a different way from other signal processors such as burst counters. By carrying out measurements using both types of processor it may be possible to reduce these uncertainties. Secondly, the power of photon correlation in processing low-light-level signals should permit the use of a convenient backscatter arrangement of a reference beam laser Doppler velocimeter to measure the line-of-sight velocity component.

Aircraft today are 20-30 dB quieter than the first passenger jets, emitting less than 1% of the noise. Further reductions in noise emission are a real challenge. The jet noise component is relatively well understood for simple geometries but it is still elusive to accurate and efficient models able to predict it for real turbofan engine nozzle configurations. Enhanced modelling of the complex three-dimensional flow from dual-flux jets of turbofan engines, in which shock waves interact with turbulent structures to generate shock-associated jet noise, is therefore required. This work explores whether lower-order hybrid Detached Eddy Simulation (DES) schemes can be used for aeroacoustic investigations of supersonic under-expanded jets. The objective of this thesis is to produce and analyse aeroacoustic results from under-expanded supersonic single and dual jets with an affordable DES numerical scheme. The main goal is to use a relatively computationally cheap numerical solver able to produce engineering accurate acoustic results for under-expanded jets. Compared to high-order full Large Eddy Simulation (LES) predictions, the second-order time accurate and up to third-order space accurate DES approach here proposed would give a strong advantage in terms of time and computational cost using a fraction of the resources of a full LES. The outcome of the work proves that the adopted approach is suitable for the analysis of BroadBand Shock Associated Noise (BBSAN) in under-expanded supersonic single jets. With respect to dual-flux coaxial jets, further tests are necessary to assess the behaviour of the DES approach in the region of interaction of strong waves with the RANS boundary layer close to the walls in order for the DES approach to be safely and confidently used as a design tool for the engine-airframe integration of wide-body civil aircraft.

This research has focused on close-in landmine detection, which aims to identify landmines in a particular landmine area. Close-range landmine detection requires both sub-surface sensors, such as metal detectors and ground penetrating radar (GPR), and surface sensors, such as optical cameras. A new multi-focus image fusion algorithm is proposed which outperforms the existing intensity-hue-saturation (IHS) and principle components analysis (PCA) algorithms on both visual and fusion parameter analysis. In addition, the proposed algorithm can save 30.9% running time than the IHS algorithm, which is the same level as the existing PCA algorithm. A novel single GPR sensor landmine detection algorithm entropy-based region selecting algorithm is proposed which uses the entropy value of the region as the feature and continuous layers instead of a hard threshold. Two A-scan based statistics algorithms and a GPR signal oscillation feature based detection algorithm are also proposed. The results show that the proposed entropy-based algorithm outperforms the existing region selection algorithm on both detection accuracy and running time. The proposed statistics algorithms and GPR feature-based algorithm outperform the edge histogram descriptor and edge energy algorithms on both detection accuracy range, running time and memory usage. In addition, the GPR feature-based algorithm can reduce the false alarm rate (FAR) by 22% for all targets at 90% probability of detection. With regards to data fusion system design, this research overcomes the limitations of the existing Bayesian fusion approach. A new Kalman-Bayes based fusion system is developed which reduces the system uncertainty and improves the fusion process. The experimental results have shown that the proposed Kalman-Bayes fusion system and enhanced fuzzy fusion system can reach 7.8% FAR at 91.1% detection rate and 6.30% FAR at 92.4% detection rate, correspondingly, outperforming the existing Bayes and fuzzy fusion systems in terms of detection ability.

Improvements in stage isentropic efficiency and reductions in stage total pressure loss are sought in a 1.5 stage axial turbine. This is representative of power generation equipment used in thermal power cycles, in a cryogenic plants, and in aeroderivative engines. The performance of cryogenic installations and of power plants can be enhanced by using turbines with a higher isentropic efficiency, by reducing the secondary flow losses. Secondary flow loss reduction is achieved by designing a non-axisymmetric end-wall for the turbine inlet stator hub. The approach is to use a novel guide groove to direct the pressure side branch of the horseshoe vortex away from the blade suction side, using a novel parametric end-wall hub surface definition. This delays the onset of the passage vortex and reduces its associated loss. The performance of the novel hub profile is compared with that from contouring the hub using representative industry best practice. For this, a three-dimensional steady RANS model with an axisymmetric hub is first validated against reference experimental measurements from RWTH Aachen. A Kriging surrogate model from the Alstom Process and Optimisation Workbench (APOW) is used to optimise the hub surface. Comparative CFD predictions with an optimised non-axisymmetric hub show a decrease in the stage total pressure loss coefficient and an increase in the stage isentropic efficiency at design and off-design. The potential benefits to a representative Liquefied Natural Gas (LNG) cryogenic cycle is assessed by thermodynamic cycle analysis. A 1.60 % increase in the axial turbine stage isentropic efficiency is predicted by using a hub contoured by the optimised guide groove compared to a 0.19 % increase by using the industry best practice. The higher turbine stage isentropic efficiency is predicted to enhance the performance of the LNG cryogenic plant by a 3.15 % rise in the Coefficient Of Performance.

For millennia magicians have entertained their audiences by manipulating perception, as well as other cognitive processes, such as attention, memory, and decision-making. In the past decade psychologists and neuroscientists have realized that this intuitive knowledge magicians have about the human mind can be used to further investigate some aspects of human perception and cognition, from a novel perspective. Whilst most of the research done in this field, to date, has been focused on subjects’ behavioural responses elicited by a magic trick, very little has used the unparalleled nature of the magic’s cognitive illusions to further study the neural bases of perception. It is within this context, that this thesis presents, in Chapter 2, two experiments, both of them, showing behavioural and evoked responses of subjects while watching an oddball sequence of continues, unedited videos of a magic trick known as Chop-Cup (where a ball appears ‘magically’ under a cup). Altogether, in both experiments, it was found that, on the one hand, subjects’ behavioural responses were strongly biased by the magic trick, and on the other, that the neural responses were modulated by the oddball sequence of stimulus presentation, as expected. In addition, in the second experiment it was found, that the same retinal stimulus, the ball (having appeared ‘magically’ or ‘naturally’) —elicited different brain responses. This novel paradigm, as well as paving the way for investigating perception and cognition under more natural conditions, required the development of a new set of technical approaches for its correct implementation, which are discussed in Chapter 1.

Heavy oil-water flow in horizontal pipes is studied by computational fluid dynamics (CFD) using the commercial CFD software ANSYS Fluent. Water-lubricated transport of heavy viscous oil “core annular flow” (CAF) is a promising technique for transporting heavy oil via horizontal pipes. This work investigates CAF numerically, using Large Eddy Simulation (LES). Its objectives are to gain an improved understanding of the behaviour of heavy oil flow through turbulent CAF in horizontal pipes and to examine the effectiveness and applicability of the LES. Heavy oil-water-air three-phase flow and heavy oil-water two-phase flow in horizontal pipe are simulated using ANSYS Fluent 16.2. A relationship between the appearance of lubricated flow and the water inflow volume fraction is identified and related to oil fouling on the pipe wall. The rise in frictional loss is characterised and closely related to oil fouling on the pipe wall from the axial pressure gradient. The model predicts that fouling can be minimized by increasing the water flow. It is found that the water phase affects the behaviour of the CAF and the axial pressure drop. It was observed that greater stability in the CAF leads to a reduction in the axial pressure drop to a value close to that for a water flow. The impact of temperature on three-phase heavy oil-water- air flow in a horizontal pipe is affected by gravity. It has been observed that the air phase and changes in the temperature influence the stability of annular flow and the axial pressure drop. Some results made during this study are validated with reference experimental and numerical results from literature and shown to be in reasonably good agreement.

The objective of this thesis is to present evidence to demonstrate the importance of layout in economical structural design, to review techniques by which structural shape may be handled as a design parameter and to determine the implications of varying layout in certain design situations. The thesis begins with a study of the theory of Michell structures. The difficulty of applying this theory directly to practical design problems then leads to a review of the linear approximation techniques for satisfying the Michell conditions for maximum material economy. The Michell theory however is restricted in its relevance to engineering practice. Consideration is therefore given to other optimisation techniques of mathematical programming. These methods permit quite general forms of merit criterion to be specified and allow a wide range of constraints to be imposed on the design. The results however can usually be justified only on pragmatic grounds rather than judged against an absolute determinable limit of merit. Dynamic programming is investigated as a means of optimising the layout of simple structures with a specified topology. Limitations in this application of the technique become evident but it is possible to use it to obtain results from which the value of varying layout may be deduced in the particular circumstances of discrete section design and of stability limitations.

A theoretical and experimental study of hydrodynamic lubrication between surfaces which touch, nominally, at a single point has been carried out. The first theoretical study involves the most general case of two surfaces of any curvature and having any directions of sliding and rolling motions. The theory has been applied to derive the dependence of oil film thickness between hypoid gears upon the design parameters. The second theoretical study is concerned with the hydrodynamic lubrication of a sphere spinning about its point of contact with a cylindrical groove. This motion is a simulation of one element of the kinematic behaviour of a ball in an angular contact bearing and calculations have been made to show the relative effect of this motion in the generation of a hydrodynamic film under these conditions. Experimental investigations have been made, using a crossed cylinders machine, into the nature of the oil film under conditions of elastohydrodynamic lubrication at point contacts. The optical interference technique has been used to derive the dependence of film thickness between cylinders of steel and glass upon speed and load using a medium viscosity mineral oil as a lubricant. The factors which affect the overall shape of the film under these conditions have also been investigated. Finally, results are presented of a direct comparison between the optical and capacitive methods of measuring the film thickness at point contacts.

The catastrophic failure of lubricated Perspex disks and cylinders rotating in heavily loaded point and line contacts in conditions of both rolling and sliding has been investigated. Observation of specimens in various stages of failure suggested that both thermal effects and mechanical stresses were involved in the failure mechanism. It has been shown that temperatures generated by conventional "flash temperature" mechanisms are not likely to be a significant factor in the mode of failure. Moreover, since this form of failure occurs under conditions of pure rolling the generation of heat by hysteresis loss appears to be a significant factor. The quasi-elastic theory of rolling friction developed by Greenwood, Minshall and Tabor has been used to derive the intensity of heat generation, and hence the temperature distribution, in the sub-surface regions; this theory has also been developed to cover a wider range of materials and conditions. The theoretical sub-surface temperatures have been compared with those measured, over a range of loads and speeds, in experiments using embedded thermocouples. The heat transfer coefficient at the surface of a rotating disk (which is a factor influencing sub-surface temperatures) has been estimated, using the Chilton-Colburn relationship, from experimental measurements of the mass transfer coefficient. Experiments to measure the coefficient of rolling friction are described, and the relationship between hysteresis loss factor, frequency and temperature is derived from the results. The effect of the variation of hysteresis loss factor with temperature upon the subsurface temperature has been discussed. The relevance of these theories and experiments to the original observations of failure of Perspex, and to the successful operation of rolling systems using polymers, has been discussed.

The Problem. The problem discussed in this thesis concerns optimal control of temperature within a finite slab of material, subject to external disturbances on one face, by applying control signals to the opposite face. Throughout the treatment is one-dimensional and the process (i.e. the slab) is assumed to be linear. introduction (Part 1). The problem is stated explicitly, and the general field of distributed-parameter control and the techniques used for solution of distributed-parameter optimal problems are reviewed. Standard Methods (Part2). The standard methods of solving "diffusion-type" problems in the time and frequency domains are described and typical solutions presented. Steady State Control in the Presence of Sinusoidal Disturbances (Part 3). Optimal control steady state solutions for the external control drive when the disturbances are sinusoidal are obtained by using the technique of slab sub-division. This reduces the problem to state variable form, and then Pontryagin's maximum principle is used on the set of first order "state variable" equations. Solutions are obtained analytically for a very simple approximation, and then analogue computer solutions of the state variable and adjoint equations for more elaborate sub-division of the slab are presented. These solutions are then synthesised into a general control equation. Finally a pure hill-climbing technique is used to generate an optimal solution. Steady State Control in the Presence of Random Disurbances (part 4). Optimal steady state solutions for the required external control drive when the disturbances are random are obtained using the technique of slab sub-division. The random disturbance treated is stationary band-limited Gaussian white noise. For a simple slab sub-division a Pontryagin analysis is used. For a more elaborate sub-division of the slab, digital computer solutions are sought via the Hamilton-Jacobi-Riccati method.