The research in this thesis deals with nonlinear control of spacecraft attitude stabilization and tracking manoeuvres and addresses the issue of control toque saturation on a priori basis. The cascaded structure of spacecraft attitude kinematics and dynamics makes the method of integrator backstepping preferred scheme for the spacecraft nonlinear attitude control. However, the conventional backstepping control design method may result in excessive control torque beyond the saturation bound of the actuators. While remaining within the framework of conventional backstepping control design, the present work proposes the formulation of analytical bounds for the control torque components as functions of the initial attitude and angular velocity errors and the gains involved in the control design procedure. The said analytical bounds have been shown to be useful for tuning the gains in a way that the guaranteed maximum torque upper bound lies within the capability of the actuator and, hence, addressing the issue of control input saturation. Conditions have also been developed as well as the generalization of the said analytical bounds which allow for the tuning of the control gains to guarantee prescribed stability with the additional aim that the control action avoids reaching saturation while anticipating the presence of bounded external disturbance torque and uncertainties in the spacecraft moments of inertia. Moreover, the work has also been extended blending it with the artificial potential function method for achieving autonomous capability of avoiding pointing constraints for the case of spacecraft large angle slew manoeuvres. The idea of undergoing such manoeuvres using control moment gyros to track commanded angular momentum rather than a torque command has also been studied. In this context, a gimbal position command generation algorithm has been proposed for a pyramid-type cluster of four single gimbal control moment gyros. The proposed algorithm not only avoids the saturation of the angular momentum input from the control moment gyro cluster but also exploits its maximum value deliverable by the cluster along the direction of the commanded angular momentum for the major part of the manoeuvre. In this way, it results in rapid spacecraft slew manoeuvres. The ideas proposed in the thesis have also been validated using numerical simulations and compared with results already existing in the literature.

A means of conducting continuous payload exchanges between the Earth and Moon would allow materials to be transported between them on a regular basis and could be used to supply vital resources to a permanent lunar colony. In addition to this, it could provide a means of returning materials, extracted from the mineral rich lunar surface, back to Earth. The use of symmetrically laden motorised momentum exchange tethers would allow these transfers to be conducted free of any conventional propulsion, purely by the exchange of momentum between the payloads, and without the subsequent loss of orbital altitude experienced by asymmetrical tether configurations. Although this is an exciting prospect it is not without its challenges, for example, if the Moon orbited a spherical Earth adhering to Kepler's laws, the transport of materials would be conducted with clockwork precision and the colonisation of the Moon would already have taken place. However, Kepler's laws are idealised to the two body motion of perfectly spherical bodies and are applicable only in the most simplified of circumstances. The Moon's motion is in reality complex and the establishment of such a system is made even more so by the oblateness effects of a non-spherical Earth acting on the tether system in Earth orbit. Adding to this complexity is the less significant but noticeable effect of the Moon's oblateness acting on a tether in lunar orbit. Other challenges include the design of a device to capture the payloads at the tether's tips at orbital velocity in addition to effecting their release at the correct instant; and the tether system's reaction to mechanical shocks which are a real possibility if velocity mismatches between the tether tips and payloads are significant. Restricting the scope of this investigation, the aim of the following is: to determine whether such a system can be realistically established when taking into account the complex nature of the Moon and resulting opportunities for payload exchanges; to establish the logistical design of the system required to conduct these regular two-way exchanges; to determine suitable configurations of the Earth and Moon orbiting tethers for conducting these exchanges when planetary oblateness effects are taken into account in addition to the complex motion of the Moon about Earth; to configure the trajectory design of the payloads between these tethers such that the logistical requirements are satisfied; and finally to investigate an anomaly observed whilst conducting simulations of the motion of a symmetrically laden tether in orbit about Earth which relates to the theory behind the concept of gravity gradient stabilisation.

In today's competitive environment, there is a continual need for organisations to invest substantial amounts of resource into the development and manufacture of products and processes, and Automotive Manufacturing Organisations are no exception to this. However, if the success rate of the projects undertaken by these organisations could be increased, then the level of resources invested in these projects could potentially be reduced. The management of risk offers a method through which the success rate of projects can be increased. However, as yet, many organisations within the Automotive Manufacturing Sector have not undertaken to integrate a rigorous method of managing the risks to their projects. This work focuses on the development and implementation of a project Risk Management Methodology into the Automotive Manufacturing Industry. The methodology was developed from a rigorous examination into the use of project and risk management into the Automotive Manufacturing Industry, as well as an investigation of risk management and project risk management processes within both the industrial and academic domains. Therefore, the Risk Management Methodology was designed to fit the needs of the users within the Automotive Manufacturing Industry, and as such, is compatible with the project management methods used within this industrial sector. The deliverables of the Risk Management Methodology were compared to 9 risk management processes and were found to give additional benefits to these processes. These were identified as the realisation of quality benefits, improvements to the technology and changes to working practices from reactive to pro-active management, which indicate that the Risk Management Methodology is more suited to Automotive Manufacturing Organisations than the other risk management processes. The Risk Management Methodology is a cyclic process, consisting of 5 stages; identification, assessment, analysis, reduction and/or mitigation and monitoring of the risks. Various tools have been developed as part of the Risk Management Methodology. They are the Front-End Assessment Tool to determine if there is a potential need to use the Risk Management Methodology, a Risk Register Database System to document the identified risks irrespective of geographical location, and the Risk Assessment Tool to enable the level of risk within the project to be reported. In addition to this, a Tracking Tool for Research and Technology Projects, based on the requirements of Rover's Technology Strategy Team, was developed to enable the probability of success of technology projects to be determined and tracked throughout their lifespan. The application of the Risk Management Methodology into 7 projects within the Rover/BMW group enabled the methods through which the assessment of the risks as well as the use of numbers within the tools themselves to be critiqued, as well as benefits of the use of the methodology and the tools to be ascertained. What was determined from its implementation was that it enabled the risks to be made visible through their identification, assessment, analysis and management. Deviations from the proposed plan could be identified, and an effort made to reduce and/or mitigate against the effects of the risks. In addition, the decision making process was improved, through increasing the amount of relevant information within the project and that there was identified a change in the working practices of the individuals and teams, from reactive, firefighting to pro-active management of the project. In conclusion, the Risk Management Methodology and its associated tools and techniques provides the means by which the risks and potential problems within projects in the Automotive Manufacturing Sector can be actively managed and as such, enables the projects to be completed successfully.

The jet acting perpendicular to a cross-flow boundary layer is a commonly studied complex turbulent flow. Our research was motivated by their potential application in separation delay devices, where jets can be used to produce streamwise vortices in a similar manner to conventional solid vortex generating vanes. This thesis addresses two problems; firstly the generation of inflow conditions for the simulation of a spatially developing turbulent boundary layer, and secondly the simulation of low velocity ratio jets interacting with the boundary layer. Our approach involved refining a popular turbulent inflow generation technique, validating the accuracy of our improved method against well established direct numerical simulation data. This turbulent boundary layer was used to simulate a low velocity ratio perpendicular jet test-case, which was validated against experimental data. Finally, a pitched and skewed jet model was investigated. Our modifications to the turbulent boundary layer inflow generation method were successful, addressing problems described by various authors regarding the stability and accuracy of the technique. Secondly we have found excellent agreement in our perpendicular jet in cross flow test-case, and have produced what we believe to be the first documented unsteady numerical simulation of the flow field behind a low velocity ratio pitched and skewed jet.

The facility layout problem (FL) is a non-linear, NP-complete problem whose complexity is derived from the vast solution space generated by multiple variables and interdependent factors. For reconfigurable, agile facilities the problem is compounded by parallelism (simultaneity of operations) and scheduling issues. Previous work has either concentrated on conventional (linear or branched) facility layout design, or has not considered the issues of agile, reconfigurable facilities and scheduling. This work is the first comprehensive methodology incorporating the design and scheduling of parallel cellular facilities for the purpose of easy and rapid reconfiguration in the increasingly demanding world of agile manufacturing. A novel three-stage algorithm is described for the design of acyclic (asynchronous), bufferless, parallel, multi-process and mixed-model production facilities for spaceframe-based vehicles. Data input begins with vehicle part processing and volume requirements from multiple models and includes time, budget and space constraints. The algorithm consists of a powerful combination of a guided cell formation stage, iterative solution improvement searches and design stage scheduling. The improvement iterations utilise a modified (rules-based) Tabu search applied to a constant-flow group technology, while the design stage scheduling is done by the use of genetic algorithms. The objective-based solution optimisation direction is not random but guided, based on measurement criteria from simulation. The end product is the selection and graphic presentation of the best solution out of a database of feasible ones. The case is presented in the form of an executable program and three real world industrial examples are included. The results provide evidence that good solutions can be found to this new type and size of heavily constrained problem within a reasonable amount of time.

Between 1935 and 1975, the British motor cycle industry declined from world supremacy to bankruptcy. The industry blamed its troubles on government policy, specifically taxation and regulation. These, it was maintained, had weakened and manufacturers' ability to effectively meet foreign competition, particularly after 1960 from Japan. The existing historiography has identified boardroom mismanagement as the main culprit. However, what the literature lacks is a wider perspective, especially one which extends to the period before 1945. Those years are critical to understanding the nature of the industry. This dissertation provides such a perspective combined with an analysis based on extensive primary research, particularly amongst recently opened trade and company records, as well as government documents at the Public Records Office. Although no single factor was entirely responsible for the industry's downfall, this dissertation will offer several explanations of varying importance. The failure to develop a cheap, lightweight motor cycle is particularly significant. This, in turn, reflected a 'management culture' which prevailed within many company boardrooms. The 'culture' was closely related to and influenced by a deep seated dedication to motor cycle sport and resulted in a narrow view of the market and the 'typical' consumer, both in Britain and abroad.

Active vibration control techniques are widely used in linear time-invariant and nonlinear systems. However, there still exist many difficulties in the application of conventional active vibration control techniques, including the following: (1) In application, some of the degrees of freedom may not be physically accessible to actuation and sensing simultaneously; (2) large flexible structures are difficult in terms of isolating one substructure from the vibration of another; (3) the incomplete understanding of the effects of softening nonlinearity may put conventional active controllers at risk; and (4) global stability of under-actuated nonlinear aeroelastic systems, resulting from actuator failure or motivated by weight and cost constraints imposed on next-generation flight vehicles, is extremely challenging, especially in the case of uncertainty and external disturbances. These intellectual challenges are addressed in this research by linear and nonlinear active control techniques. A new theory for partial pole placement by the method of receptances in the presence of inaccessible degrees of freedom is proposed. By the application of a new double input control and orthogonality conditions on the input and feedback gain vectors, partial pole placement is achieved in a linear fashion while some chosen degrees of freedom are free from both actuation and sensing. A lower bound on the maximum number of degrees of freedom inaccessible to both actuation and sensing is established. A theoretical study is presented on the feasibility of applying active control for the purpose of simultaneous vibration isolation and suppression in large flexible structures by block diagonalisation of the system matrices and at the same time assigning eigenvalues to the chosen substructures separately. The methodology, based on eigenstructure assignment using the method of receptances, is found to work successfully when the open-loop system, with lumped or banded mass matrix, is controllable. A comprehensive study of the effects of softening structural nonlinearity in aeroelastic systems is carried out using the simple example of a pitch-flap wing, with softening cubic nonlinearity in the pitch stiffness. Complex dynamical behaviour, including stable and unstable limit cycles and chaos, is revealed using sinusoidal-input describing functions and numerical integration in the time domain. Bifurcation analysis is undertaken using numerical continuation methods to reveal Hopf, symmetry breaking, fold and period doubling bifurcations. The effects of initial conditions on the system stability and the destabilising effects of softening nonlinearity on aerodynamic responses are considered. The global stability of an under-actuated wing section with torsional nonlinearity, softening or hardening, is addressed using a robust passivity-based continuous sliding-mode control approach. The controller is shown to be capable of stabilising the system in the presence of large matched and mismatched uncertainties and large input disturbance. With known bounds on the input disturbance and nonlinearity uncertainty, the continuous control input is able to globally stabilise the overall system if the zero dynamics of the system are globally exponentially stable. The merits and performance of the proposed methods are exemplified in a series of numerical case studies.

Modern military aircraft employ weapon bays for carriage and release of stores. The clearance of these stores for release from aircraft may require several flight tests at a range of conditions where the trajectories of released stores are obtained through accelerometers located on the store. Although effective, this is expensive and time consuming and only limited flight tests can be accomplished at critical conditions. Predictions made using store release analysis through wind tunnels and Computational Fluid Dynamics (CFD) have the potential to reduce the number of flight tests required for store clearance. The motivation for the current work, stems from the need to investigate carriage and release of a store from a weapon bay, idealised as a rectangular cavity, through a unique blend of disciplines comprising Computational Fluid Dynamics, Computational Structural Dynamics (CSD), Computational Aero- Aeroacoustics (CAA) and High Performance Computing (HPC). Detached-Eddy Simulations (DES) of flow in clean cavities were carried out to compare two cavities of different aspect ratios for configurations with doors-off and doors-on. Both cavities had similar acoustic signatures and the addition of doors channelled the flow causing acoustic waves to propagate further away from the cavity. DES computations were carried out for a store at different positions relative to a cavity that showed that a store at carriage position pacified the cavity acoustics the most. Fin tip displacements were small for a store at carriage position and exhibited buzzing characteristics. This was similar to the case where a store was positioned at the shear layer of a cavity but with slightly larger displacements. While fin displacements were not large, the results highlighted concerns for fin fatigue life. Comparisons between rigid and elastic fins showed small differences in loads, however, aeroelastic simulations showed that where resonance of structural and cavity modes occurred, large amplitude fin oscillations were predicted. Scale-Adaptive Simulations (SAS) were validated against experimental data for clean cavities and were found to be similar to DES results and could be run at a larger time-step. The cost savings and similarities of SAS to DES encouraged its use for store release computations. Store release computations from a cavity were conducted and the variability of a stores trajectory due to the unsteady cavity flow-field was investigated. Visualisations using Q-criteria highlighted instantaneous structures that were in contact with the store fins causing the trajectory to vary for different release times. Overall, the thesis suggests the use of SAS as an affordable method for analysing store release computations from a cavity and highlights the need for a stochastic evaluation of trajectories from transonic cavities. A study comparing different signal lengths for post-processing unsteady pressure data revealed that, the minimum CFD signal length required to capture all dominant tones was around 0.05s. Different post-processing methods for spectral content were compared and the use of Maximum Entropy Methods (MEMs), based on Burgs Estimator, was suggested as it not only captured dominant tones but also predicted the highest Sound Pressure Levels (SPLs), that could be used to produce the maximum boundary of a given signal.

The problems of transport technology were analysed; present vehicles are polluting, inefficient and run largely on unsustainable fossil fuels. The theory proposed here is that a hydrogen fuel cell battery hybrid system is the best for future vehicles; zero emission, twice as efficient and running on renewable hydrogen from biomass, wind or solar. Early testing compared a crude Micro-cab prototype (compressed hydrogen, Ballard fuel cell, lead acid batteries and an electric motor) with a hydrogen combustion dual fuel van to assess the technical demands of the proposed technology. Then a battery scooter was modified and tested to show that a plug-in hydrogen battery hybrid with hydride store could have benefits which were quantifiable. A computer model was developed to predict the performance of this system. Reducing dissipation by removing DC converters was shown to be beneficial. A prototype Micro-cab was analysed and tested to show how improved drivetrain components could increase the vehicle efficiency. The main part of the project was to use these ideas to build an urban car driven by a plug-in hydrogen fuel cell lithium ion battery hybrid with efficient motors, no DC/DC converters and belt/pulley drive. The results showed that with a 2kg pressurised hydrogen store at 350bar, such a vehicle had good urban performance and a range of 200miles. The conclusion was that the overall design concepts were correct and that costs and hydrogen infrastructure were the main future difficulties of future application.

This thesis is concerned with inter-vehicle communications supporting the deployment of future safety-related applications. Through use case analysis of the specific communica- tions requirements of safety related and traffic efficiency applications, a data dissemination framework is proposed that is able to meet the various message delivery requirements. More specifically, this thesis focuses on the subset of the proposed framework, which provides geocasting, i.e. addressing a geographical area on the road network, and local zone connectivity, providing neighbour awareness, for safety related applications. The enabling communications technology for inter-vehicle communications based on IEEE 802.11 wireless local area network devices and the associated lack of reliability it presents for the distribution of safety messages in broadcast mode, form the main topic of this thesis. A dissemination scheme for safety related inter-vehicular communication applica- tions, using realistic vehicular traffic patterns, is proposed, implemented and evaluated to demonstrate mechanisms for efficient, reliable and timely delivery of safety messages over an unreliable channel access scheme. The original contribution of this thesis is to propose a novel data dissemination protocol for vehicular environments, capable of simultaneously achieving significant economy of messaging, whilst maintaining near 100% reliable message delivery in a timely manner for a wide variety of highway traffic flow scenarios, ranging from sparsely, fragmented networks to dense, congested road networks. This is achieved through increased protocol complexity in inferring and tracking each vehicular node’s local environment, coupled with implementing adaptation to both local data traffic intensity and vehicular density. Adaptivity is achieved through creating and employing an empirical channel access delay model and embedding the stochastic delay distribution in decisions made at the network layer; this method of adaptivity is novel in itself. Moreover, unnecessary retransmissions arising from the inherent uncertainty of the wireless medium are suppressed through a novel three-step mechanism.