The work covered in this thesis concerns the performance of a commercially available AI-Zn-In alloy, particularly in above ambient temperature conditions where the anode is completely or partially buried. Initial work involved the construction and commissioning of a heat transfer rig for use in long term performance studies. The anode under test was subjected to a series of long term laboratory performance tests and a series of short term electrochemical tests, at both ambient temperatures and at varying levels of heat transfer. The maximum test temperature used corresponds to a maximum internal temperature in the anode of ~1 05 °C. The surrounding electrolyte was maintained at a constant temperature of 4 °C. The internal and interfacial temperatures of the anode were monitored closely throughout all experiments. The electrolyte used for both tests was a mixture of bentonite clay and/or BS artificial seawater. This electrolyte represents the worst case scenario likely when this anode is in industrial usage. The long term testing of the anodes involved monitoring the potential and current flow over 1000 hours. The anodes were tested over a range of applied current densities, 500, 1000 and 2000 mA/m-2 ; in addition, the anodes were tested as a simple galvanic couple with steel. It was found that under all test temperatures and conditions, the steel was adequately protected. With increasing temperature, the potential of the anode became slightly less negative and the potential of the steel decreased dramatically. As shown by previous workers it was found that the highest value of efficiency at each test temperature was displayed by the anode subjected to the highest impressed current density. The efficiency of the test anodes was found to decrease steadily with increasing temperature, reaching a minimum of approximately 20% at80°C. It was also found that the effect of heat transfer was more detrimental to the current capacity than the same temperature applied isothermally. A series of short term electrochemical tests were undertaken, ac impedance, repassivation kinetics and potentiodynamic sweeps. The following features were identified; the application of ac impedance has shown that at high temperatures, the anode is not activating fully although corrosion processes are occurring, confirming that self corrosion is the major reaction under these conditions. The minium chloride concentration necessary to activate the alloy has been shown to be between 0.5 and 1.0% w/w chloride. Chloride adsorption onto the metal surface is thought to be an essential stage in the activation process. Iron at the surface of the anode' is also thought important in the activation process. There are three main complimentary factors which are causing the reduction in current capacity or efficiency. Firstly, the level of self corrosion increases as the test temperature is increased. Secondly, there is an increase in the formation of corrosion products around the anode, particularly aluminium hydroxide, due to the increased'level of self corrosion. Finally, the level of dissolved oxygen adjacent to the anode is highly dependant on both the temperature and the nature of the test environment. In the clay/seawater mixture at high temperature, the concentration and rate of diffusion of oxygen will be greatly reduced.

Premium tubular connections (sometimes referred to as rotary shouldered thread connections), are commonly used to complete a production string in a well in the oil and gas industry. These are attached to threaded pipe ends using a bucking unit and a pre-defined torque value. The torque value is calculated using the coefficient of friction between the two surfaces and a well-known torque equation. The existing technology relies on the coefficient of friction approximated by interpolation, or extrapolation, of empirical data. This may become inaccurate due to the variation of surface finish and/or operation conditions and lead to over or under torque of the connections. A failure such as a leaking connection can result in high financial implications as well as environmental ones. The project was aimed to develop a bench test which adequately represents field conditions. This benchmark test was then used to investigate how CoF was affected by changes in the main variables so that these variables can be better controlled. Therefore, a propriety laboratory test system was developed to allow measurements of friction and galling under these conditions and to examine the sensitivity of friction to initial surface topography, contact pressure, sliding speed and lubricant type. Samples were produced to represent variables which were possible within the oil and gas industry. A set of data was produced to identify the different frictional values for each combination of variables. The results showed that the initial surface topography and the burnishing in repeated sliding have significant effects on friction. iv In order to understand the correlation between the effects of initial surface roughness and burnishing during the sliding process on the coefficient of friction, a theoretical approach was taken to produce a mathematical model whichutilised the data from the laboratory testing. This gave predictions of the wear, roughness and friction with sliding distance. This data was then compared to the physical testing and found to be in line with the results. The results helped to understand how friction is related to external circumstances in the operation of premium tubular connections.

Driven by an application to the combined cooling and lubrication by oil of an aero-engine bearing chamber the research in this thesis studies non-isothermal thin liquid film flow on the inside of a circular cylinder driven at its surface by an air-shear and interfacial flux of liquid droplets. Flow conditions inside the bearing chamber preclude using classical lubrication theory models since these neglect some of the physical effects, specifically inertia and heat convection, which are important to this problem. To this end a depth-averaged approach, based on hydraulics modelling within a lubrication theory framework, is adopted which ensures all the relevant physical mechanisms are retained in the model for the film. In limiting cases the model is shown to be consistent with published models for thin film rimming flow. Leading-order inertial effects were found to extend the range of possible thin-film solutions beyond those predicted by lubrication theory alone. This can allow a smooth progression in solution from low-inertia cases, where the film may feature recirculations and steep-fronts, to high-inertia cases of uniform film flow as the film Reynolds number is increased. The accuracy of the depth-averaged model for film temperature is examined for the case of uniform film flow over a heated flat plate. Here an analytical solution exists and the model is found to give very good agreement with this. Film dynamics and thermal characteristics of the film, in particular those relating to the interfacial mass flux of droplets, are analysed in detail. The depth-averaged model is used to provide insight into the motivating bearing chamber application through calculation of oil film temperature characteristics and a parameter space showing the dependence of film residence times on chamber operating conditions.

With the growth in requirement for a high reliability of power supply, stability of the power system and the minimum requirement for control systems becomes more and more significant. The most popular way to solve the problem of stability is to install power system stabilizers (PSSs) on synchronous generators in related power systems. The conventional methods for designing PSS are generally based on the compensation approach for the phase and eigenvalue of the generator model. In recent decades, H-norm based robust PSS has been developed because of the system uncertainty of power grids. In another aspect, wind power has evolved into a significant renewable energy source and increased at an outstanding rate. Stability problems of power system with large wind farms became more and more challenging. Some wind plant modelling methods, for which PS Ss are not taken into consideration, have been developed and widely used in practical applications. The present study is concerned with a comprehensive power system stability analysis based on an improved H-nOl'ffi robust controller design method and a novel modelling approach for doubly fed induction generator (DFIG) wind turbines. Initially, one improved lemma, enhanced with LMI regional pole placement, is developed for linear matrix inequality eLMI) based H2/Hoo robust output feedback controller design. Robust PS Ss are designed based on the approach and they are tested in both single and multimachine systems. A novel DFIG wind turbine model is then built up and tested with the robust PSS in both single and multi-machine systems to see the oscillations damping ability. Finally, based on the robust PSS, a large multi-machine power system with wind parks is selected for a comprehensive stability analysis. Simulated examples and case studies are employed in this study to demonstrate the effect of new PS Ss. The simulation results clearly suggest that the proposed PSS can solve the stability problem of damping oscillations in power systems with large wind parks.

Fuel economy has become an important consideration in forklift truck design, particularly in Europe. A simulation of the fuel consumption and performance of a forklift truck has been developed, validated and subsequently used to determine the energy consumed by individual powertrain components during drive cycles. The forklift truck used in this study has a rated lifting capacity of 2500kg, and is powered by a 2.6 litre naturally aspirated diesel engine with a fuel pump containing a mechanical variable-speed governor. The drivetrain consisted of a torque convertor, hydraulic clutch and single speed transmission. AVL Cruise software was used to simulate the vehicle powertrain, with coupled Mathworks Simulink models used to simulate the hydraulic and control systems, and fuel pump governor. The vehicle has been simulated on several performance and fuel consumption drive cycles with the main focus being the VDI 2198 fuel consumption drive cycle. To validate the model, a truck was instrumented and measurements taken to compare the performance and instantaneous fuel consumption to simulated values. The fuel injector pump was modified and calibrated to enable instantaneous fuel flow to be measured. The model has been validated to within acceptable limits and demonstrates how the model can be used to compare the fuel consumption and performance trade-offs when selecting drivetrain components.

Multi-furcation and reconfiguration in mechanisms interested many researchers over past twenty years since the early investigation by Wohlhart in 1996. This Dissertation systematically investigates multi-furcation and reconfiguration in mechanisms including recognition of motion branches, factors causing motion branches and how these factors result in different motion branches in serial and parallel mechanisms by line geometry. Among these factors, relative orientations of joint-axes and the corresponding multi-furcation and reconfiguration are further discussed. The Dissertation starts from multi-furcation in the derivative mechanism from the "queer square" origami fold by allowing a full rotation of joints and reveals fourteen motion branches with four different motions as single translation, double translations and other two single screw motions about perpendicular axes. Two kinds of multi-furcation are demonstrated by the derivative mechanism, on account of its first six branches maintaining unchanged relative orientations of joint-axes and its last eight branches caused by variable relative orientations of joint-axes. Mobility and motion characteristics of the derivative mechanism are discussed. The Dissertation then studies reconfiguration with different motion characteristics caused by different relative orientations of joint-axes and proposes a new parallel mechanism with two motion branches. The transformation between spatial translational motion branch and spatial rotational motion branch is caused by different configurations of reconfigurable joints. Constraint disposition and motion characteristics are presented in group-algebraic and screw-based analyses. A discussion of motion branches with different motion directions caused by variable relative orientations of joint-axes is provided. The 3-US and 3-RRS parallel mechanisms with reconfigurable joints are proposed followed by motion investigations. The platform implements anticlockwise folding and clockwise deploying motion in the first motion branch and the inverse motion as clockwise folding and anticlockwise deploying motion in the second motion branch. According to special configurations and motion features, novel mechanisms presented in this Dissertation have wide applications in fields of manufacture with multiple tasks, design of architectures and aerospace industry.

The intrinsic complexity and variability of typical real time control problems makes a generalised approach to producing control systems difficult to specify. Due to a lack of standardisation, current machine controllers are usually extremely difficult to configure, support and integrate together in a generalised manner. These problems have severely hindered the development and subsequent application of advanced factory automation. The exploitation of advanced computer technology, particularly modern software methods can now enable a consistent machine control structure to be maintained for diverse applications of widely differing complexity. This thesis addresses the need for a major change in the design of machine control systems and proposes the use of a reference architecture which offers a consistent approach to the control of real time industrial operations. A broad based look at existing control systems focuses on the functiona,lity they currently offer in the control of various categories of industrial operations. A study of current manufacturing automation highlights the functional similarities between the control requirements of different industrial processes both in terms of their control structure and hierarchical communication requirements for factory integration. Given this commonality it is proposed that all industrial controllers should logically be based upon a common hardware independent architecture. A design methodology has been devised, termed Universal Machine Control (UMC) which enables individual machine controllers to be created (with functionality closely matched to their specific applications) whilst still maintaining common structural and communications features. This methodology aims to simplify the process of defining, programming and controlling systems built up from user defined mechanical hardware. A modular design framework or reference architecture for machine control has been derived which allows control systems to be modelled in a generalised manner. A particular implementation of the control architecture conforming to this reference model and an associated definition environment have been created. The implementation is based on the selective use of modern computer methods and emerging standards for real-time control. A demonstration system has been produced targeted at the flexible assembly of printed circuit boards. The possible application areas for this control philosophy are however extremely diverse and it could have a significant impact on automation methods.

The focus of the present study has been directed towards the development and optimisation of a new high-energy loss / severe service control valve cage. From this, an advanced design methodology has been created which is able to relate the effects of strong three-dimensionality in the flow to the specific geometrical features of the flow path design through the valve cage, thus allowing the design of the cage to be optimised and aid the prediction of troublesome phenomena such as cavitation. The chosen cage design, which consisted of a number of flow paths in which were located a series of densely packed, low aspect ratio, staggered cylinder arrays, was evaluated against existing cage designs of this type. From this point the critical geometrical features of the flow path though the cage were identified and used to define the basis for a parametric study. This study was carried out using computational fluid dynamics (CFD) to simulate the flow through 140 different cylinder array configurations. The results from this were used to develop a series of analytical expressions able to represent the effect of each geometrical feature on the properties of the fluid flow. These were then compiled into a design methodology which could be used to size the valve cage. To validate the computational predictions, a senes of experimental measurements of the velocity distributions within five representative models of the cylinder arrays, considered in the parametric study, were taken using particle image velocimetry (PIV). This required the use of a specially built flow rig and the selection of a line fluid able to provide a near refractive index match with the Perspex cylinders. The chosen line fluid was liquid paraffin BP. A prototype cage was installed into a real process environment to test the performance of the new design methodology and its ability to predict the onset of cavitation. The performance of the prototype cage showed a good agreement with the computational predictions. As a consequence of this study, the author has developed a new approach to the design of a control valve cage which allows the cage to be sized and optimised against a given set of process conditions. It is envisaged that this new method will be of benefit in the future design of control valves, leading to an improved level of performance across the Industry

The main objective of this research study was to develop numerical models to analyse the mechanical and fracture properties of through-thickness reinforced (TTR) structural joints. The development of numerical tools was mainly based on the finite element (FE) method. A multi-scale approach was used: the bridging characteristics of a single reinforcement was studied at micromechanical level by simulating the single-pin response loaded either in mode-I or in mode-II. The force-displacement curve (bridging law) of the pin was used to define the constitutive law of cohesive elements to be used in a FE analysis of the global structure. This thesis is divided into three main parts: (I) Background, context and methodology, (II) Development for composite joints, and (III) Development for hybrid metal-composite joints. In the first part the objectives of the thesis are identified and a comprehensive literature review of state-of-art throughthickness reinforcement methods and relative modelling techniques has been undertaken to provide a solid background to the reader. The second part of the thesis deals with TTR composite/composite joints. The multi-scale modelling technique was firstly applied to predict delamination behaviour of mode-I and in mode-II test coupons. The bridging mechanisms of reinforcements and the way these increase the delamination resistance of bonded interfaces was deeply analysed, showing how the bridging characteristics of the reinforcement features affected the delamination behaviour. The modelling technique was then applied to a z-pin reinforced composite T-joint structure. The joint presented a complicated failure mode which involved multiple crack path and mixed-mode delamination, demonstrating the capability of the model of predicting delamination propagation under complex loading states. The third part of the thesis is focused on hybrid metal/composite joints. Mode- I and mode-II single-pin tests of metal pin reinforcements embedded into a carbon/epoxy laminate were simulated. The model was validated by comparing with experimental tests. Then the effects of the pin geometry on the pin bridging characteristics were analysed. The model revealed that both in mode-I and mode-II small pins perform better than large pins and also that the pin shape plays an important role in the pin failure behaviour. The modelling technique was then applied to simulate a metal-composite double-lap joint loaded in traction. The model showed that to obtain the best performance of the joint an accurate selection of pin geometry, pin arrangement and thickness of the two adherends should be done.

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