In this thesis we consider the problems that Proper Names cause in the analysis of unedited, naturally-occurring text. Proper Names cause problems because of their high frequency in many types of text, their poor coverage in conventional dictionaries, their importance in the text understanding process, and the complexity of their structure and the structure of the text which describes them. For the most part these problems have been ignored in the field of Natural Language Processing, with the result that Proper Names are one of its most under-researched areas. As a solution to the problem, we present a detailed description of the syntax and semantics of seven major classes of Proper Name, and of their surrounding context. This description leads to the construction of syntactic and semantic rules specifically for the analysis of Proper Names, which capitalise on the wealth of descriptive material which often accompanies a Proper Name when it occurs in a text. Such an approach side-steps the problem of lexical coverage, by allowing a text processing system to use the very text it is analysing to construct lexical and knowledge base entries for unknown Proper Names as it encounters them. The information acquired on unknown Proper Names goes considerably beyond a simple syntactic and semantic classification, instead consisting of a detailed genus and differentia description. A complete solution to the 'Proper Name Problem' must include approaches to the handling of apposition, conjunction and ellipsis, abbreviated reference, and many of the far from standard phenomena encountered in naturally-occurring text. The thesis advances partial and practical solutions in all of these areas. In order to set the work described in a suitable context, the problems of Proper Names are viewed as a subset of the general problem of lexical inadequacy, as it arises in processing real, un-edited, text. The whole of this field is reviewed, and various methods of lexical acquisition compared and evaluated. Our approach to coping with lexical inadequacy and to handling Proper Names is implemented in a news text understanding system called FUNES, which is able to automatically acquire detailed genus and differentia information on Proper Names as it encounters them in its processing of news text. We present an assessment of the system's performance on a sample of unseen news text which is held to support the validity of our approach to handling Proper Names.

Those who study world politics are divided between the traditional Realist paradigm, which depicts an international political system dominated by states involved in a 'power struggle' in pursuit of their 'national interest', and an emergent approach that includes in the analysis a wider range of political actors and defines the nature of politics very differently. The latter approach sees the central process of world politics as being the mobilisation of support in respect to the composition of the global political agenda and contest over the various issue positions. This thesis examines the Palestinian Question as a case study of a mobilisation process, that involved a non-state actor playing a crucial role in introducing to the global agenda an issue previously of low salience to other actors. The Palestinian Question throughout the 1950s and 1960s was treated on the global political agenda as a by-product of the Arab-Israeli conflict. It was perceived as a 'refugee problem', the solution of which was envisaged within an overall settlement of the Arab-Israeli conflict. Yet, within less than a decade of the re-appearance of an indigenous Palestinian national movement a significant section of the international political system changed its attitude towards the Palestinian problem. It was not any more perceived simply as a 'refugee problem' but one of 'self-determination'. In this thesis the analysis of the mobilisation process that brought the Palestinian issue to the forefront of the world political agenda is guided by a dynamic model applied to four different levels of analysis. The first level is constituted by the Palestinian community. Then there is the Arab governmental level. The third level is made up of various regional groupings, such as the Non-Aligned, the Latin Americans, the European Community and the East Europeans. The final level is the global one, represented by the United Nations political system. The analysis reveals the dynamic and interactive nature of the mobilisation process across different levels of analysis and the way in which the different positions held on the Palestinian issue have converged towards a relatively common stand.

Multimedia (MM) Applications currently suffer from an ad hoc development process. This places the usability and effectiveness of many MM products in doubt. This thesis develops a theoretically motivated design method and tools to address these problems. The thesis is based on an analysis of the cognitive processes of attending to and comprehending an MM presentation. A design method is then developed based on these cognitive processes. The method addressesth e problem of selecting media to presenting information requirements,h ow to design the media to effectively deliver the desired content, how to combine verbal and visual media successfully, and how to direct the user's attention to particular part of the presentation. A number of studies are then presented which provide validation for the method's claims. These include eye tracking to analyse the user's reading / viewing sequence, and tests of expert and novice recall of MM and conventional text / speech presentations. A set of re-authoring studies show that application of guidelines improves retention of the content. The method is supported by a design advisor authoring tool. The tool applies the guidelines using a combination of a critiquer and expert system. The tool demonstrates that the guidelines are tractable for implementation, and provides a novel approach to providing authoring advice. Both the method and the tool are also validated in case studies with novice users. These demonstrate that the method and tool are both usable and effective.

This thesis investigates user interaction in virtual environments and usability requirements to support that interaction. Studies of the design and use of virtual environments are used to demonstrate the need for interface design guidance. A theory of interaction for virtual environments is proposed, which includes predictive models of interactive behaviour and a set of generic design properties for supporting that behaviour. The models elaborate on D.A. Norman's cycle of action to describe the stages involved in three modes of behaviour: task and action based, exploratory and reactive. From the models, generic design properties are defined for various aspects of the virtual environment, such as its objects, actions and user representation. The models of interaction are evaluated through empirical studies of interactive behaviour which compare observed interaction patterns with those predicted. The generic design properties are evaluated through usability studies that investigate the links between missing design properties and usability problems encountered. Results from the evaluation studies provide general support for the theory and indicate specific refinements required. A controlled study is used to test the impact of the theory on interaction success, by comparing performance in virtual environments with and without implementation of the generic design properties. Significant improvements in interaction are found with the use of a virtual environment, after the predicted design properties have been implemented. Design guidelines are then developed from the theory and a hypertext tool designed to present the guidelines. The tool and guidelines are evaluated with industrial virtual environment designers to test the usability and utility of the guidance. Results indicate that the guidance is useful in addressing the practical problem of designing virtual environments for usability. Therefore, this thesis fulfils its objective of developing interface design guidelines for virtual environments, using interaction modelling as a theoretical base. Furthermore, it provides an improved understanding of user interaction in virtual environments and can be used to inform further theories, methods or tools for virtual environments and human-computer interfaces.

This thesis applies models of user action to usability evaluation of direct manipulation interfaces. In particular, the utility of a Model of Action for assisting novice evaluators in usability tests is investigated. An initial model of user action is proposed, based on the theory of action proposed by Norman (1986). This model includes a description of knowledge sources used in interaction, error types and user responses to errors. The model is used to interpret data on user behaviour and errors in an empirical study of MacDraw I. This study used the Protocol Analysis technique proposed by Ericsson and Simon (1984). Protocol evidence shows that the search and specification stages of user action could usefully be treated as separate in terms of user knowledge recruitment and the nature of system support. The Model of Action is then expanded and modified to account for the empirical findings. The new model distinguishes knowledge-based, rule-based and skill-based processing in Direct Manipulation (DM) interaction, using the distinction drawn by Rasmussen (1986). These processing levels are explicitly linked to types of presentation technique and categories of user error. This is developed into a technique for determining system causes of usability problems. A set of mental dialogue tokens (roles) are developed to assist novice evaluators in the interpretation of error causes. Roles are linked to types of user error in the cycle of action in a diagnostic model. This model forms the basis of a budget method for use by novice evaluators, named Model Mismatch Analysis (MMA). These developments are tested by a two-tier study of user performance on Microsoft Word. The empirical evidence validated the taxonomy of errors, and tests the utility of five retrospective data analysis techniques. A study of novice evaluator performance is reported, comparing the MMA method to the Usability Checklist proposed by Ravden and Johnson (1989). The MMA method is shown to be the more efficient approach. To summarise, models of Direct Manipulation action are shown to assist novice evaluators both in the diagnosis of usability problems, and the selection of remedies.

An increasing number of organisations are procuring off-the-shelf software products from commercial suppliers. However, there has been a lack of methods and software tools for such requirements acquisition, product selection and product procurement. This thesis proposes a new method called PORE (Procurement-Oriented Requirements Engineering) which integrates existing requirements engineering techniques with those from knowledge engineering, feature analysis, multi-criteria decision-making and argumentation approaches to address the lack of guidance for acquiring requirements to enable evaluation and selection of commercial-off-the-shelf (COTS) software. PORE is designed in part from conclusions drawn from real-world case studies of requirements acquisition for complex software product selection. Such studies are reported in this thesis. The PORE method is part goal-driven and part context-driven, in that it exploits models of the candidate COTS software and customer requirements as well as process goals to guide a requirements engineering team. The method's approach and mechanisms is demonstrated using a well-known commercial electronic-mail system. A number of studies are presented to provide validation for the method. These include three studies in three different organisations to select COTS software products and one study of requirements engineering experts to elicit their knowledge. The results from these studies demonstrated that the method is usable and effective. The thesis concludes with a discussion of future work to improve the PORE method and future research directions on requirements engineering for COTS-based systems development.

This thesis explains theoretical issues concerned with paradigm incommensurability and the solutions offered by various critical systems writers. The problems of "imperialism" are outlined together with an analysis of the meta-theoretical views which purport to avoid imperialism. It is suggested that researchers attempting to understand alien or incommensurable paradigms or cultures often succumb to imperialism in its various guises. Three models of methods used by such researchers are described. The last of these, the model of critical appreciation, incorporates two crucial components advocated by Habermas and endorsed by Bernstein: critical self-reflection based upon an analogy of Freud's model of dream analysis, and an explicit critique of ideology. Methodological guidelines are offered which draw on an analogy of dream-analysis and on historical reconstruction as ideology-critique. It is suggested that any social inquiry must contain elements of "reflexive" (philosophical) and "scientific" (practical) inquiry together with ideology-critique and critical self-reflection in order to bring about the emancipation of individuals and groups. A model of self-society dynamics reveals the need for reflexive inquiry, discourse and action (as exemplified in the critical appreciation process) in any efforts to transform 'self' or 'society'. Consideration turns to the relationship between critical thinking and pluralism. The enriched version of critical appreciation is shown to require an a prior commitment to a new, discordant pluralism, which it also suggests in its modus operandii. In particular, the 'either/or' problematique presented by many writers is transformed into a 'both/and' juxtapositioning which lends its support to the form of pluralism involving both critical self-reflection and ideology-critique. The fully elaborated model of critical appreciation will finally be shown to fulfil the demands of the commitments of critical systems thinking.

Power quality problems have been identified with wind generation sites and their connection with the distribution network. The main aim of this research is to put forward and develop models for the conventional components in a power system, but with provision for the representation of wind farms. To develop the necessary tools and computational methods that can be embedded in programmes in such a way that economic and security assessments can be carried out on present and future wind-based networks that are likely to be highly decentralised in future. The goal has been accomplished using MATLAB programming and the 'power library' tools.

Tidal energy conversion devices (TECDs) are in development throughout the world to help reduce the need for fossil fuels. These devices will generally be mounted on the seabed and remain there over a period of years. Most of the previous research on TECDs has focused on their power extraction capability and efficient design. The handful of studies which have focused on the effects of the devices on the marine environment have not considered small-scale three-dimensional phenomena occurring in the flow near the rotor. These phenomena are likely to disturb the marine environment by altering the dynamics of sediment. The accurate prediction of the rapidly changing flow down-stream of a TECD and its influence on the seabed poses a challenge. The nature of the interactions between such a flow and sediment has not been experimentally established. Predictions of these interactions, as is necessary for an assessment of the effects of the devices on the seabed, need to account for the depth-dependence of the flow velocity and its changes during the tidal cycle. The difference between the typical time-scales of the development of the rotor wake and the tidal cycle represents a difficulty for the computational modelling of the interactions between the device and the tidal flow. This dissertation presents an inviscid analysis of the flow down-stream of horizontal- axis, vertical-axis and cross-flow TECDs by means of computer modelling. The Vortic- ity Transport Model, modified to simulate the flow down-stream of a TECD mounted onto the seabed, predicts the shear stress inflicted by the flow on the seabed. The shear stresses on the seabed, generated by small-scale vortical structures in the wake down-stream of the devices, cause sediment to uplift. This process along with the sub- sequent motion of the sediment is simulated by a sediment model implemented into the Vorticity Transport Model. The critical bed shear stress is known as a threshold for initiation of sediment motion, therefore the relative difference between the stress on the seabed and the critical bed shear stress, called the excess bed shear stress, is chosen here as an indicator of the impact of the TECDs on the seabed. The evolution of the instantaneous stresses on the seabed is predicted to vary with the configuration of TECD. The results suggest that the average excess bed shear stress inflicted on the seabed by the horizontal-axis device increases with the inflow velocity during the flood part of the representative tidal cycle and that the increase can be expressed by a simple algebraic expression. It is also predicted that the impact of this device on the seabed does not monotonically decrease with increasing separation between the rotor and the seabed. In addition, the relationship between the excess bed shear stress and the position of the rotor is established. Furthermore, the simulations indicate that the wake down-stream of the horizontal-axis device is lifted by the flow away from the seabed, which result in a confinement of its impact to the vicinity of the rotor. In contrast with the horizontal-axis configuration, it is concluded that the vertical-axis and cross-flow configurations of the rotor would promote the erosion of the seabed further away from the device, at a location where the wake approaches the seabed again and that this location depends on the inflow velocity. The predicted effects of these devices on the marine environment need to be con- sidered in advance of their installation on the seabed.

The prevalent approach to developing cognitive models of music perception and composition is to construct systems of symbolic rules and constraints on the basis of extensive music-theoretic and music-analytic knowledge. The thesis proposed in this dissertation is that statistical models which acquire knowledge through the induction of regularities in corpora of existing music can, if examined with appropriate methodologies, provide significant insights into the cognitive processing involved in music perception and composition. This claim is examined in three stages. First, a number of statistical modelling techniques drawn from the fields of data compression, statistical language modelling and machine learning are subjected to empirical evaluation in the context of sequential prediction of pitch structure in unseen melodies. This investigation results in a collection of modelling strategies which together yield significant performance improvements over existing methods. In the second stage, these statistical systems are used to examine observed patterns of expectation collected in previous psychological research on melody perception. In contrast to previous accounts of this data, the results demonstrate that these patterns of expectation can be accounted for in terms of the induction of statistical regularities acquired through exposure to music. In the final stage of the present research, the statistical systems developed in the first stage are used to examine the intrinsic computational demands of the task of composing a stylistically successful melody The results suggest that the systems lack the degree of expressive power needed to consistently meet the demands of the task. In contrast to previous research, however, the methodological framework developed for the evaluation of computational models of composition enables a detailed empirical examination and comparison of such models which facilitates the identification and resolution of their weaknesses.