Medical education and practical training in surgery is changing, by shifting from an on the job learning paradigm, which possesses problems such as that it is unpredictable, dependent on clinical needs and that patient safety may be jeopardised, to an evidence-based surgical skills training driven by curricular needs, and acquiring basic surgical skills prior to assisting in the operating theatre and thus reducing operation duration. Towards achieving this goal, virtual reality (VR) simulators are used in minimally invasive surgery for technical skills training at the beginning of the learning curve, but have not yet been adapted for open surgery due to its complexity for simulation. This thesis investigated the potential of using a VR simulator for training in orthopaedic hand surgery, with an emphasis on providing a meaningful, effective and motivating addition to current training methods for surgical procedures. A review of literature, preliminary research projects and currently available surgical systems revealed limited results on whether a VR simulation of orthopaedic hand surgery could be created, fulfilling the needs of medical experts. Therefore, a study investigating the current state of medical education and to understand the expectations on such a simulator was carried out, which resulted in the identification of promising medical scenarios for simulation (such as carpal tunnel release, distal radius fracture treatment or surgical incision) and in requirements for its development. Different software frameworks have been evaluated for their ability for use by analysing five developed demonstrators, with the result that a custom implementation of a six-degrees-of-freedom haptic algorithm was required. By following a human-centred design approach, a VR surgical simulator with inbuilt objective measures of assessment has been developed, allowing applying a plate, drilling holes, measuring their lengths, inserting screws and taking virtual X-rays, supported by haptic feedback for increased realism and teaching aspects not possible by common computer-based simulators, such as feeling the resistance when drilling through the cortical bone. By close collaboration with medical experts and following user interface design principles, a carried out medical evaluation of the simulator showed that the simulator was well-received by the targeted young doctors and medical students, that relevant aspects of the implemented medical scenario are taught and that the users’ performance can be assessed. The findings of this work showed that it is possible to create an interactive VR simulator aimed at early stages to learn basic orthopaedic principles of open surgery using the example of the treatment of distal radius fractures in a meaningful manner. It addresses issues in the current medical education and enables learning educational objectives repeatedly in reusable medical scenarios and in a safe and controlled environment, without the risk of harming patients, and thus contributing to improved quality and patient safety when proceeding to the operating theatre.

The value of Remote Condition Monitoring for the real-time evaluation of the structural integrity of critical components is undeniable. Fibre-reinforced polymer composites are a class of materials which offer significant advantages over conventional metal alloys used for manufacturing load bearing structures in cases where weight and/or energy consumption need to be kept to a minimum, for example automotive and aerospace applications. This is due to the excellent strength to weight ratio that FRPCs exhibit. However, their strongly anisotropic microstructure of poses significant challenges for Non-Destructive Evaluation of the actual structural health of components made from such materials. Acoustic Emission is a passive condition monitoring technique based on the detection of elastic stress waves emitted when damage evolves in a structure. Conventional piezoelectric AE sensors need to be surface-mounted as their embedding in FRPCs is impractical. Fibre Optic Acoustic Emission Sensors (FOAES) offer a distinct advantage since they are light weight, have small size and can be effectively embedded in composite laminates. Moreover, they can be multiplexed with the entire structure being monitored more effectively. This study has focused in the evaluation of the manufacturing process and characterisation of FOAES. Comparison of their performance with conventional commercial sensors was carried out.

This thesis is dedicated to the special class of bistatic SAR, where the transmitter is a Global Navigation Satellite System (GNSS) and receiver is fixed on the ground. Such a kind of geometry is suited for ground deformation monitoring. The employment of such a navigation satellite brings many advantages, such as shorter satellite revisit time (8-9 days) compared to imaging radar such as Envisat (35days). Moreover, due to large number of satellites deployed (at least 4 satellites could be seen at any time), persistent monitoring of a given area can be achieved from multiple angles simultaneously. This thesis presents research results on the imaging capability of SS-BSAR with GNSS and a stationary receiver. Firstly, the system is outlined and the reason of selecting GNSS as transmitter of opportunity is justified. The power budget and resolution were then analyzed. The end to end signal processing, from received raw data leading to SS-BSAR image, is described. Four experimental data sets acquired at different imaging scenarios are used to test our system hardware and signal processing algorithms mentioned below. It can be seen from the obtained images and associated analysis that such a system has the capability of real scene imaging.

As the feature sizes in VLSI technology shrink to less than 100 nm the effects due to the quantisation of electronic charge begin to emerge. There are a small number of carriers and impurities and the statistical variation in their number have significant effects on the threshold characteristics of the devices that hamper their large scale integration into future ULSI.The complex potential landscape arising from the Coulomb force, with its sharp localised peaks and troughs, faces problems due to band limiting in meshes and places heavy burdens on the integration techniques. A computationally efficient solution to the problem of band-limiting is presented and is shown to provide an accurate description of the electrostatics. This work also introduces a highly efficient and numerically stable multigrid solver, for Poisson's equation, that can cope with the complex potential distributions on large meshes. The study of ionised impurity scattering is used to validate these molecular dynamics simulations. Results have shown that the Brownian method - despite precluding the use of adaptive integration schemes - gives a good approximation to the standard results and has the advantage of smoothing away errors that can build up during the integration of motion and drives the system towards thermal equilibrium. The greatest hurdle to be cleared before these three-dimensional simulations can be practicable is the sheer computational effort that is required. The implementation of the problem on parallel architectures has been explored and discussed. The methods developed in this work are demonstrated through the simulation of an 80 nm dual-gate MESFET. The results were verified by comparing them with those from a commercial drift-diffusion simulator. The threshold behaviour of devices has been investigated through the study of the formation of conduction channels in blocks. The percolation threshold gives the point when conductive paths form across the gate barrier. The results from the FET simulation were found to be in agreement with the earlier studies on the blocks.

This thesis investigates analogy as a paradigm for retrieving, understanding and customising reusable specifications during requirements engineering. Cooperation between software engineers and support tools is necessary for effective analogical reuse. Retrieval uses a computational implementation of analogical reasoning to search and match many reusable specifications. On the other hand understanding, transferring and adapting specifications requires cooperation between the tool and software engineer. Cooperative support was designed for less-experienced software engineers with most to gain from successful specification reuse. Deliverables from this research have implications for software engineering, artificial intelligence, cognitive science and human-computer interaction. Specification retrieval is founded on a framework of software engineering analogies. This framework includes a set of domain abstractions describing key facts about software engineering domains. A computational model of analogical reasoning which matches domain descriptions to these abstractions was designed, implemented and evaluated during user studies with a prototype reuse advisor. An intelligent dialogue acts as a front-end to this retrieval mechanism by acquiring key domain facts prior to retrieving domain abstractions. This dialogue was designed from empirical studies of software engineering behaviour during requirements capture and modelling. Design of support tools for specification understanding and transfer was based on cognitive task and reasoning models of software engineering behaviour during analogical reuse and mental models of analogical understanding. Two empirical studies of inexperienced software engineers identified problematic mental laziness manifest as specification copying. A third study of expert software engineers who successfully reused specifications identified strategies for effective reuse. Detailed findings from all three studies informed the design of tool-based support for specification understanding and transfer. Findings also have implications for the design of tools to support other requirements engineering activities.

The development of a statistical compact model strategy for nano-scale CMOS transistors is presented in this thesis. Statistical variability which arises from the discreteness of charge and granularity of matter plays an important role in scaling of nano CMOS transistors especially in sub 50nm technology nodes. In order to achieve reasonable performance and yield in contemporary CMOS designs, the statistical variability that affects the circuit/system performance and yield must be accurately represented by the industry standard compact models. As a starting point, predictive 3D simulation of an ensemble of 1000 microscopically different 35nm gate length transistors is carried out to characterize the impact of statistical variability on the device characteristics. PSP, an advanced surface potential compact model that is selected as the next generation industry standard compact model, is targeted in this study. There are two challenges in development of a statistical compact model strategy. The first challenge is related to the selection of a small subset of statistical compact model parameters from the large number of compact model parameters. We propose a strategy to select 7 parameters from PSP to capture the impact of statistical variability on current-voltage characteristics. These 7 parameters are used in statistical parameter extraction with an average RMS error of less than 2.5% crossing the whole operation region of the simulated transistors. Moreover, the accuracy of statistical compact model extraction strategy in reproducing the MOSFET electrical figures of merit is studied in detail. The results of the statistical compact model extraction are used for statistical circuit simulation of a CMOS inverter under different input-output conditions and different number of statistical parameters. The second challenge in the development of statistical compact model strategy is associated with statistical generation of parameters preserving the distribution and correlation of the directly extracted parameters. By using advanced statistical methods such as principal component analysis and nonlinear power method, the accuracy of parameter generation is evaluated and compared to directly extracted parameter sets. Finally, an extension of the PSP statistical compact model strategy to different channel width/length devices is presented. The statistical trends of parameters and figures of merit versus channel width/length are characterized.

London Black Cab Drivers have a rich and documented history of mobile work practices that are geographically distributed and driven by situated choices for everyday work. To date mobile studies researchers have not made a close examination of these mobile working practices, hence there is a gap in mobile studies concerning this type of worker. This dissertation aims to study the evolution of Black Cab drivers' work practices since the introduction of mobile Information and Communication Technology (mICT) in their everyday work. The theoretical framework for the research is based on studies of taxi drivers' work practices, mobility research, computer supported co-operative work and organisational change promoted by IS interventions. The ontology of this research pinpoints the factors influencing the situated and idiosyncratic choice associated with the use of mICTs when carrying out planned and unplanned work. The case study references a 420-year history of "old", established work practices as a comparison framework. When compared with the "new" and situated choice of mICT-supported work, it becomes apparent that there has been a change in the dynamics of how this type of work is actually completed. Embedding and mixing elements of self-referenced work - as discretionary and independent - with working practices in which mutual interdependencies are supported by the use of mICT aids seems to provide the case for a re-negotiation of the working practices model as well as its associated organisational forms, together with a social shift in the definition of the role and skills required to perform this type of mobile work. The empirical data have been sourced from one-to-one interviews and video recordings using a combination of ethnographic methods and interpretative approaches for the data analysis. This dissertation makes a theoretical and practical contribution to mobile studies by understanding the changing of working practices; it further offers methodological insights for studying mICT-supported work. Finally, it provides a formative evaluation of the new organisational forms emerging as mICT has been introduced to everyday Black Cab work.

Diabetes Mellitius is a major chronic disease with multi-organ involvement and high-cost implications. Although it has been demonstrated that structured education can control the risk of developing these complications, there is a substantial room for improvement in the educational services for these patients. E-learning can be a good solution to fill this gap. A system dynamics model was developed in this study to highlight the potential return on investment in these systems.

In this thesis various aspects of the electromagnetic effects influencing the commutation of uncompensated single phase universal motors are investigated. An introduction to the subject as well as a review of significant literature on the subject are given. The literature review includes classical text books about commutator motors as well as more recent publications about the mathematical analysis of the commutation of universal motors. Subsequently, the analysis of the most important inductances of the machine is outlined that comprises the analytical and numerical calculation as well as the measurement of the machine inductances using different measurement techniques. Moreover, a brush model for commutation analysis of small commutator motors is presented. Equivalent circuits of the brush are established for the cases of one coil shorted and two coils shorted by one brush, and a strategy to obtain their elements is proposed. This uses a dedicated finite difference program to calculate the effective brush resistance between all pairs of terminals. The treatment of the boundary conditions is critical in this process. The resulting terminal resistances are regarded as combinations of a set of internal resistances and this nonlinear relationship is inverted to obtain the internal resistors using a modified Newton-Raphson method. Results are presented showing the influence of anisotropy and geometry, and a simplified example of commutation analysis using the model established is given. In the next step the arcing phenomenon in analysed mathematically. Equations are given for the pre-arcing phase, the arcing phase and the post-arc oscillation. Equivalent circuits for the different phases are proposed and the equations are derived strictly from a circuit point of view. In the analysis a constant arc voltage (confirmed by experimental data and literature on the subject) and a minimum uncommutated residual current necessary for arc ignition are assumed. Those quantities are adopted from reviewed literature and used in the calculations. The design of a motor test bench is described that allows to measure the motor performance according to the principle of the reaction dynamometer. The load machine is mounted on air bearings to minimize possible torque errors in the measurements. A measured torque speed characteristic of a universal motor is shown as well as the torque as a function of the motor current. These measurements were carried out at reduced motor voltage to keep the shaft speed within reasonable limits. Furthermore, theoretical and experimental investigations are carried out in order to estimate how strongly certain rotor coils undergoing rapid current changes affect each other due to mutual coupling and how the mutual coupling changes in the presence of a damping field winding. Several FEA simulations are performed in order to get an insight into the flux pattern if rotor coils are acting on each other and the field winding is allowed to impose its damping effect on the rotor coils. Simple AC measurements are performed as well as di/dt - tests using a more complex oscillating circuit for measurements of the change of the di/dt of a rotor coil with and without the presence of an active field winding. Additionally, investigations are carried out in order to analyse the influence of power cord and source impedances on the ability of the field winding of an uncompensated universal motor to damp flux variations caused by the commutation process. The motor is regarded as a harmonic generator with the power cord and the source impedance acting as a load. Rotational tests are carried out with different loads connected to the field winding and the Fourier spectrums of the field voltage are evaluated. In the final stage a simulation model is described that uses deductions from the previous chapters and that simulates the electromagnetic behaviour of the machine including the complex problem of brush commutation. Measured and calculated signals suitable for validation of the model were compared in order to evaluate the accuracy of the model with regard to motor performance and commutation analysis.

The object of this thesis is to form an understanding of the origin of the problems associated with proton-exchanged waveguides, and to investigate possible solutions. Chapter 1 gives a brief introduction to the properties of lithium niobate, and discusses the methods available for fabricating optical waveguides in the bulk material, with particular emphasis on waveguide fabrication by the proton-exchange process. Some of the devices which have been fabricated by proton-exchange are discussed. The problems associated with proton-exchanged waveguides are reviewed. Chapter 2 deals with the physical and chemical characterisation of proton-exchanged waveguides fabricated using neat benzoic acid melts. The extent of proton-exchange is determined as a function of fabrication time and temperature using optical waveguide prism-coupler measurements, infrared absorption spectroscopy, and atomic absorption spectroscopy. Chapter 3 is concerned with the problem of waveguide mode-index stability. Using a hydrogen isotopic-exchange reaction, the extent of which is obsrved via infrared absorption spectroscopy, information on the (room-temperature) mobility of protons within the guiding layer is obtained for waveguides fabricated using neat benzoic acid melts. The recently reported process of fabricating waveguides in lithium niobate by deuterium-exchange is investigated. The behaviour of proton-exchanged and deuterium-exchanged waveguides with respect to reaction with atmospheric water vapour is investigated, and the optical properties of deuterium-exchanged waveguides are studied. In Chapter 4, a study of annealed and dilute-melt proton-exchanged waveguides is presented. It is shown, using prism-coupler measurements and infrared absorption spectroscopy, that ennealed and dilute-melt waveguides can have very similar optical properties, depending on the amount of annealing and the lithium benzoate mole-fractions used. The extent of proton-exchange is determined with time (between 215oC and 235oC) for dilute-melt waveguides produced using lithium benzoate mole-fractions of up to 1.1%. Isotopic-exchange in annealed and dilute-melt waveguides is also investigated, both at room-temperature and at temperatures commonly used for annealing. A possible explanation for the poor optical properties of (neat-melt) proton-exchanged waveguides is given. Chapter 5 deals with a study of propagation losses (using the two-prism method) and the electro-optic effect in x- and z-cut proton-exchanged waveguides. Measurements of r33 (in proton-exchanged waveguides) and r22 (in titanium-indiffused waveguides) are carried out using an external interferometric method designed by the author. The results of Chapter 4 are used to establish a method by which losses below 0.5dB/cm and a substantially restored electro-optic effect can be achieved (using a combination of dilute-melt fabrication with post-exchange annealing). Prior to the waveguide measurements, the bulk electro-optic effect is investigated for congruent, incongruent, MgO-doped, and annealed (high-temperature) crystals. Finally, in Chapter 6, a summary of the thesis is presented, and suggestions for future work are given.