Computing and Information Systems - Theses
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ItemA multistage computer model of picture scanning, image understanding, and environment analysis, guided by research into human and primate visual systems(University of Melbourne, Faculty of Engineering,, 1983)This paper describes the design and some testing of a computational model of picture scanning and image understanding (TRIPS), which outputs a description of the scene in a subset of English. This model can be extended to control the analysis of a three dimensional environment and changes of the viewing system's position within that environment. The model design is guided by a summary of neurophysiological, psychological, and psychophysical observations and theories concerning visual perception in humans and other primates, with an emphasis on eye movements. These results indicate that lower level visual information is processed in parallel in a spatial representation while higher level processing is mostly sequential, using a symbolic, post iconic, representation. The emphasis in this paper is on simulating the cognitive aspects of eye movement control and the higher level post iconic representation of images. The design incorporates several subsystems. The highest level control module is described in detail, since computer models Of eye movement which use cognitively guided saccade selection are not common. For other modules, the interfaces with the whole system and the internal computations required are out lined, as existing image processing techniques can be applied to perform these computations. Control is based on a production . system, which uses an "hypothesising" system - a simplified probabilistic associative production system - to determine which production to apply. A framework for an image analysis language (TRIAL), based on "THINGS". and "RELATIONS" is presented, with algorithms described in detail for the matching procedure and the transformations of size, orientation, position, and so On. TRIAL expressions in the productions are used to generate "cognitive expectations" concerning future eye movements and their effects which can influence the control of the system. Models of low level feature extraction, with parallel processing of iconic representations have been common in computer vision literature, as are techniques for image manipulation and syntactic and statistical analysis� Parallel and serial systems have also been extensively investigated. This model proposes an integration Of these approaches using each technique in the domain to which it is suited. The model proposed for the inferotemporal cortex could be also suitable as a model of the posterior parietal cortex. A restricted version of the picture scanning model (TRIPS) has been implemented, which demonstrates the consistency of the model and also exhibits some behavioural characteristics qualitatively similar to primate visual systems. A TRIAL language is shown to be a useful representation for the analysis and description of scenes. key words: simulation, eye movements, computer vision systems, inferotemporal, parietal, image representation, TRIPS, TRIAL.
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ItemAgent-based 3d visual tracking( 2000-07)We describe our overall approach to building robot vision systems, and the conceptual systems architecture as a network of agents, which run in parallel, and cooperate to achieve the system’s goals. We present the current state of the 3D Feature-Based Tracker, a robot vision system for tracking and segmenting the 3D motion of objects using image input from a calibrated stereo pair of video cameras. The system runs in a multi-level cycle of prediction and verification or correction. The currently modelled 3D positions and velocities of the feature points are extrapolated a short time into the future to yield predictions of 3D position. These 3D predictions are projected into the two stereo views, and are used to guide a fast and highly focused visual search for the feature points. The image positions at which the features are re-acquired are back-projected in 3D space in order to update the 3D positions and velocities. At a higher level, features are dynamically grouped into clusters with common 3D motion. Predictions from the cluster level can be fed to the lower level to correct errors in the point-wise tracking.
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ItemOrganization-oriented systems: theory and practice( 1999-02)We investigate the problem of developing a formal language for specifying and reasoning about real-time embedded distributed computer systems. In particular we investigate the problem of developing a theoretical framework for specifying and analyzing different aspects of real-time embedded distributed coordination. In addition to the theoretical framework we also consider the practical aspects of developing real-time embedded distributed systems. (For complete abstract open document)
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ItemShadowboard: an agent architecture for enacting a sophisticated digital self( 2001-09)In recent years many people have built Personal Assistant Agents, Information Agents and the like, and have simply added them to the operating system as auxiliary applications, without regard to architecture. This thesis argues that an agent architecture, one designed as a sophisticated representation of an individual user, should be embedded deep in the device system software, with at least equal status to the GUI – the graphical user interface. A sophisticated model of the user is then built, drawing upon contemporary Analytical Psychology – the Psychology of Subselves. The Shadowboard Agent architecture is then built upon that user model, drawing both structural and computational implications from the underlying psychology. An XML DTD file named Shadowboard.dtd is declared as a practical manifestation of the semantics of Shadowboard. An implementation of the Shadowboard system is mapped out, via a planned conversion of two existing integrated systems: SlimWinX, an event-driven GUI system; and XSpaces, an object-oriented tuplespace system with Blackboard-like features. The decision making mechanism passes logic terms and contraints between the various sub-agent components (some of which take on the role of Constraint Solvers), giving this agent system some characteristics of a Generalised Constraint Solver. A Shadowboard agent (built using the system) consists of a central controlling autonomous agent named the Aware Ego Agent, and any number of sub-agents, which collectively form an integrated but singular whole agent modelled on the user called the Digital Self. One such whole-agent is defined in a file named DigitalSelf.xml – which conforms to the schema in Shadowboard.dtd - which offers a comprehensive and generic representation of a user’s stance in a 24x7 network, in particular - the Internet. Numerous types of Shadowboard sub-agents are declared.
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ItemManaged DC power reticulation systems( 1999-11)Electric power engineering, as it applies to low-voltage power reticulation in buildings and industrial sites, is ripe for a ‘paradigm shift’ to bring it properly into the Electronic Age. The conventional alternating-current approach, now over a hundred years old, is increasingly unsatisfactory from the point of view of plant and appliance requirements. Alternative approaches can deliver substantial cost savings, higher efficiencies, power quality improvements, and greater safety. Power reticulation systems in the future can be expected to differ from present systems in two key respects. The first is a greatly increased role for direct current; the second is the augmentation of the power system with a wide range of ‘management’ technologies. Combining these two trends, which can already be observed today, leads to consideration of ‘managed DC’ power reticulation systems, operating from AC bulk supply mains via AC-DC converters.
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ItemChoosing an auditor : corporate governance, interpersonal associations and investor confidence( 2000-06)This thesis provides evidence enabling an analysis of systemic director-auditor links, their nature, their determinants, their association with audit quality as an important component of corporate governance, and investor confidence in companies displaying these links. The motivation for examining interpersonal associations between directors and auditors comes from several sources. First is the observation that auditing is a knowledge-based service the quality of which is difficult to evaluate even after the product has been experienced, adding to the complexity of the purchasing decision (Murray 1991). The use of personal contacts to scan the business environment, disseminate information and reduce uncertainty is likely to assist that evaluation and so aid in auditor selection. One manifestation of these personal contacts is directors who hold directorships on more than one board, creating networks of ties between companies known as interlocking directorates. It tends to be non-executive or external directors who create these ties because they have more time to devote to multiple directorships. Interlocking directorates are a long-standing phenomenon that has been examined in the economics, organisational behaviour and sociology literatures and are argued to engender trust, and mediate transactions. Some countries restrict such directorate ties between industry competitors because of their potential to encourage collusion and competitive disadvantage but Australia has no such restrictions. In order to promote practice growth and firm survival, public accounting firms are known to tap into these networks, which often include former employees, encouraging personal contacts with, amongst others, directors of clients and potential clients. In this way, it is argued, companies interlocked through common directors tend to be audited by a common audit firm with the links extending to even audit partners. Extensive analysis of these interlocking directorates supports these arguments and finds that the association between interlocking directorates and director-auditor links becomes stronger as intra-industry and within confined geographical region data partitioning occurs and varies across audit firms. This variation across firms is subsequently used to model with some success auditor choice - even within the Big 6. Systematic ties between directors and audit firms and/or audit partners potentially threaten at least the appearance of auditor independence, if not the fact. On the other hand, following the DeAngelo (1981)auditor size argument, the potential loss of a ‘family’ of clients associated with a single director if audit quality is degraded may actually enhance audit quality. This thesis argues that directors value personal contact in auditor-client relationships but are aware of the potentially damaging connotations arising from such interpersonal associations and the potential for investor disquiet about them. Implicit in this argument is an assumption that investors are both interested and active in matters of corporate governance, including the audit as a component of corporate governance. As such, the formation of director-auditor links is argued to be contingent on the balance of power between directors and shareholders and the strength of other aspects of corporate governance beside the audit function. Empirical results support this hypothesis only for interlocking created between two or more directors of companies in the same industry. Evidence of director-auditor link association with audit quality is then sought by analysing qualifications and discretionary accruals in the presence of these links. Although alternative explanations are possible, some evidence is found of reduced audit quality. However, using the frequency with which an investor chooses to invest across companies audited by the same auditor as a measure of investor confidence in that auditor, results show that audit quality attributes are valued by investors and that director-auditor links are not associated negatively with investor confidence. Additional tests that examine the association between director-auditor links and various measures of organisational performance find little evidence of negative connotations. Public policy implications flow from the findings and these are discussed together with limitations and ideas for future research.
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ItemPredicting the priority of email messages using stylistic features( 2001)LASSIE (Learning Apprentice System for Sorting Incoming Email) is an email management tool that has been constructed in order to demonstrate a possible solution to the problem of email overload. It is designed to help users manage their incoming messages more efficiently by sorting the messages according to their level of urgency. This thesis discusses the motivation and requirements for such a system, and describes the design, implementation, and evaluation of LASSIE. We identify stylistic features that are good indicators of message urgency, describe how these features can be extracted from plain text messages, and present an algorithm for inferring the relationship between these attributes and the message urgency for any individual user. We discuss the considerations involved in constructing a practical email management tool and describe the design decisions that were made in constructing LASSIE. The results of a user trial indicate that LASSIE is able to achieve a high level of predictive accuracy and is readily adopted by users, although improvements in its long-term performance are desirable.
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ItemMaximizing benefits from enterprise systems( 2001)This study investigates how organizations can maximize benefits from their Enterprise Systems (ES). The results suggest that making optimal use of an Enterprise System is an on-going challenge best managed by successive cycles of system exploration, redesign, and use. Each cycle results in successively better configured software and enhanced organizational processes. Each cycle requires core process managers' commitment and management initiatives to explore and control the positive and negative effects caused by the four distinctive characteristics of Enterprise Systems: pre-packaged features, evolving functionality, sophisticated knowledge, and application infrastructure. The study was conducted over three connected phases that sought answers to three research questions: • What business benefits can be realized from the use of Enterprise Systems? • How and when do organizations realize net benefits from Enterprise Systems? • How can organizations manage the use of Enterprise Systems to maximize net benefits? Phase one answers question one, by developing a comprehensive framework of ES benefits organized around five business dimensions: operational, managerial, strategic, IT infrastructure, and organizational. This framework was synthesized from the literature on ES and IT effectiveness, enhanced by analyzing benefits identified from 233 Web cases, and tested in 34 confirmatory cases. This phase established the basis for further analysis of ES benefits. Phase two applies the ES business benefit framework from phase one to answer question two. Business benefit realization processes are tracked over three to four years in in-depth case studies of four Australian utilities. Patterns of Perceived Net Benefit Flow are identified and graphed in each of the five benefit dimensions. The results show that ES benefit realization is a life-long process, with different benefits being developed in different patterns in the five different dimensions, with results possibly varying across core processes within the one organization. The duration and intensity of benefits also varied among the companies. Using cross-case analysis, the types of ES benefit and the interrelationships between different benefit dimensions are explained. Moreover, various causes of benefit variation were analyzed, with the finding that benefits are mainly driven by management of the four ES-specific characteristics of ES use identified above. Following from the case analysis in phase two, phase three answers question three by further exploring ES management in the four case-study organizations. Six propositions are induced from the four case studies and tested for reasonableness with seven additional ES adopters in different industries. Based on this in-depth case exploration, four different strategies for ES management are identified: process replication, system modification, process modification, and system exploration. By comparing business conditions and the implications of the different ES management strategies, the study suggests that the most effective strategy is system exploration. System exploration involves results in a series of business-led initiatives involving changes to both the ES software and business processes that lead to incremental improvements to the Enterprise System.
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ItemFundamentals of agent computation theory: semantics( 2001)About 5 years ago, the idea of software agents escaped from an obscure existence within the arcane field of Artificial Intelligence, and it is now running rampant through computer science, the software industry and the media, mutating violently as it goes and infecting many who come into contact with it. Despite humble origins in the study of Philosophy of Mind, the term agent has come to be applied to a diverse and disparate range of software constructs, and threatens soon to displace object from its primal position. Every computer scientist knows what agents are, or should be, although scant agreement upon definitions has been achieved, as so many variously qualified uses of the label now flourish. In the Artificial Intelligence research community where it was nurtured, however, the term still has a reasonably specific meaning: an agent is a situated or embedded system which participates in an ongoing interaction with some environment which it can observe and act upon. By assumption, an agent's behaviour is purposeful or motivated: it is thought of as wanting to perform some set of activities or achieve some set of goals and trying to do so when suitable opportunities present; in general it may be viewed as monitoring and controlling itself and its environment so as to bring about or maintain internal or external situations that it in some sense prefers. A very concrete example would be a robot, situated in the physical world, tasked to achieve certain objectives, but required to make its own moment-to-moment decisions about how and when to do so. But more often than not an agent inhabits an entirely artificial environment, within a single computer or a distributed network such as the Internet. It is with agents in this sense that this thesis is concerned. (From introduction)
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ItemExploring social aspects of requirements engineering: an ethnographic study of Thai systems analysts( 1999)Requirements engineering has been considered as an important phase for information systemsdevelopment. There has been much evidence, which shows how the lack of understanding ofusers' requirements has led to information systems failure and rejection by clients.Requirements engineering emerged from software engineering focusing on elicitingrequirements and finalising requirements specification for systems analysts to design systems. There has been a focus in requirements engineering research on the technical area. This study focuses on the social dimensions of requirements engineering, which has been poorly understood due to a lack of research in this area. The social dimensions of requirements engineering are broad and cover many areas of social activities. This study focuses on the influences of culture and values on requirements engineering processes and on the tools/techniques employed by systems analysts for requirements engineering. The data collected was from intensive interviews with eight Thai systems analysts. These interviews were transcribed and analysed using the accepted practices of hermeneutics. Culture is learned by members in a society. They learn how to behave to their parents, relatives, peers, and their superiors throughout their development from home, school, and workplace. Thai culture is high in power distance, group focus, emotion and relationship focus, and is characterised by a dislike of uncertain situations. These unique characteristics in Thai culture influence the requirements engineering processes and the use of tools/techniques for requirements engineering. Three important issues emerged from the study. They are a continual evolving of requirements, long decision-making processes, and misconceptions about requirements and of the problem domain. These three issues are shown to be influenced by the process of requirements engineering as practiced by the participant systems analysts. Thai culture and values construct the learning process in Thai society and form the emotional and relationship structures in Thailand. These two unique issues are shown to influence the use of tools/techniques for requirements engineering by the participant systems analysts. This study shows that local culture and values have influenced requirements engineering processes. Therefore, systems analysts need to take social factors into consideration for the best selection and adaptation of existing requirements engineering processes to suit their client's culture, values, and work practices. This study's findings are crucial for multinational information systems consulting organizations, operating in Thailand, to gain a better understanding of Thai culture and its impact on the use of requirements engineering methodologies. The study also assists consulting organisations to better manage requirements engineering processes and understanding implicit factors that create problems during requirements engineering and throughout the information systems development processes.