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In the United Kingdom, the implementation of large-scale Information System (IS) projects has led to multifarious problems over the last few decades, and this seems to be an ongoing situation. As a result, within the public sector organisations, a number of information systems have failed to meet their pre-specified goals in spite of the large amount money and effort spent on IS projects. Information system projects are highly complex and the complexity is varied based on the different aspects involved including technical, organisational, and social, while the traditional concepts have less of an effect when aiming to achieve considerable improvement to cope with the increasing complexity of the situation. This was apparent in the study of two examples of large-scale IS failures in the UK public sector, whereas the attention was on examining discrete elements without considering the potential relationships between the elements. The current study, therefore, proposes a system approach as an alternative to understanding the nature of large-scale IS failures in the UK public sector. The systems approach, as an advanced movement in management science, seeks to identify social context and organizational issues and to use a combination of methodologies, methods, tools, and techniques to help problem solvers better control problematic situations. Thus, the Systems Approach is privileged because it offers a holistic approach to look at the problematic situation rather than being focused solely on a particular aspect instead of the interconnected relationships among its parts. The alternative approach benefits from the new problem solving and practical intervention strategies toward a better understanding of the complexity, diversity, and change of the problematic situations, while providing a comprehensive insight into the real-world problem of IS failure. This extends to identifying the contradictory issues related to power, conflict, and culture affecting the situation. Within the Systems Approach the researcher employed critical pluralism to the current study, which is theoretically built upon a combination of methodologies and methods designed for a particular intervention. Some findings of the research disclose that large-scale IS failure in the UK public sector is treated inadequately, and solutions proposed to reduce the rate of failure ignore this complexity. The findings also reveal that there are four factors affecting large-scale IS failure in the UK public sector: political factors; organisational factors; technical factors; and human factors. The founding related to the methodology, the researcher found that critical pluralism appears able to capture a set of systemic processes: appreciation; analysis; assessment; and action. All these processes were conducted collectively and supported by a particular type of collected data activities in the way of identifying the natures of the IS system and its associated sub-systems. Finally, by conducting a particular Systems Approach technique to assess the IS failure problem in the UK public sector context, it cannot be claimed that the solution is applicable to other situations in another context because the approach itself views any problematic situation as unique and hard to be generalised. Nevertheless, the discovery of such solutions leads to the accumulation of knowledge that contributes to reductions in the rates of IS failure in general.

A Boolean formula in predicate logic is an expression on Boolean variables that evaluates to either True or False. This fundamental construct has many important applications in computer science, such as the validation of system models. However, as these models are extended, the number of variables in the expression grows exponentially, creating problems for efficient representation. Traditional data structures used to represent Boolean formulas containing a large number of variables become especially inefficient for operations such as checking whether the expression is satisfiable. Binary Decision Diagrams (BDDs), a relatively new data structure used to represent Boolean formulas, enjoy several advantages over these traditional data structures. First, BDDs are often compact, even for Boolean formulas involving many variables. Furthermore, they are canonical representations for Boolean formulas, meaning equivalence checking can be done effectively. Finally, they can be efficiently combined to represent more complex formulas.The goal of this study is to develop a provably correct software realization of the BDD. This realization can be verified with respect to precise specifications using proofs, not just checked using test cases as is typical with software implementations. Achieving this goal requires solving problems in three phases: designing a behavioral specification based on a mathematical model, developing a layered implementation in Java, and establishing a correspondence between the implementation and model. The full implementation of a provably correct BDD realization provides an efficient method of representing system models that users can be completely confident in using.

When a container carrying a magnetized ferrofluid is subjected to external mechanical stimuli, the sloshing motion of the magnetized ferrofluid generates a time-varying magnetic flux, which can be used to induce an electromotive force in a coil placed adjacent to the container. This process generates an electric current in the coil, and therewith, can be used to transduce external vibrations into electric energy providing a unique approach for vibration energy harvesting using liquid-state transduction materials. As compared to traditional vibratory energy harvesters that employ soli transduction elements, this approach offers several advantages including, but not limited to, conformability to different shapes and increased sensitivity to external excitations. In this dissertation, a bench-top experiment was first constructed to demonstrate the feasibility of the proposed concept for vibratory energy harvesting. A rectangular plastic container carrying ferrofluid was placed inside a pick-up coil which is wound around a ferrite core. The whole setup was mounted on an electrodynamic shaker table which provided a controlled acceleration at the containers base. The external magnetization is applied using permanent magnets with maximum magnetic field intensity of 92 mT. Series of experiments were carried out to determine the optimal configuration of coil windings with respect to the sloshing and magnetic field directions. It was found that the output power of the device increases an order of magnitude when the coil is wound perpendicular to the sloshing motion and magnetic field lines. For the optimal configuration determined experimentally, a nonlinear analytical model which governs the electro-magneto-hydrodynamics of the harvester was developed. An approximate analytical solution of the model was obtained using perturbation methods for two different types of excitation; namely for a case involving the primary resonance excitation of the first mode and a case involving the principle parametric resonance of the first two modes. For the case involving the primary resonance of the first mode, it was observed the approximate analytical solution fails to capture the qualitative behavior of the harvester’s response for some ferrofluid height to container width ratios. Upon further inspection, it was observed that for those critical height-to-width ratios, the sloshing conditions are such that a two-to-one internal resonance between the first two sloshing modes can be activated. To account for the internal resonance, a modified version of the perturbation solution was devised and used to obtain a solution of the governing equations capable of capturing the influence of the internal resonance on the dynamics. Overall, it was shown that the developed model is capable of capturing the qualitative behavior of the dynamics of the harvester for both cases of excitation and for various magnetic field distributions. It was observed that the orthogonality of the magnetic field distribution along the width the container to the shape of the mode being excited plays a critical role in determining the output power of the harvester. Specifically, regardless of the input excitation level and the size of the induced sloshing waves, very little energy can be harnessed from the environment when the magnetic field distribution is an even (odd) function of the containers width while the mode shape being excited is an odd (even) function of the width. It was shown that, unlike the primary resonance scenario, a threshold excitation level must be achieved in the principle parametric resonance case before the harvester can produce measurable voltage levels. This threshold increases with the strength of the applied magnetic field.