Computing and Information Systems - Theses
Permanent URI for this collection
Search Results
1 - 8 of 8
-
ItemDigital forensics: increasing the evidential weight of system activity logs( 2007)The application of investigative techniques within digital environments has lead to the emergence of a new field of specialization that may be termed ‘digital forensics’. Perhaps the primary challenge concerning digital forensic investigations is how to preserve evidence of system activity given the volatility of digital environments and the delay between the time of the incident and the start of the forensic investigation. This thesis hypothesizes that system activity logs present in modern operating systems may be used for digital forensic evidence collection. This is particularly true in modern organizations where there is growing recognition that forensic readiness may have considerable benefits in case of future litigation. An investigation into the weighting of evidence produced by system activity logs present in modern operating systems takes place in this thesis. The term ‘evidential weight’ is used loosely as a measure of the suitability of system activity logs to digital forensic investigations. This investigation is approached from an analytical perspective. The first contribution of this thesis is to determine the evidence collection capability of system activity logs by a simple model of the logging mechanism. The second contribution is the development of evidential weighting criteria that can be applied to system activity logs. A unique and critical role for system activity logs by which they establish the reliability of other kinds of computer-derived evidence from hard disk media is also identified. The primary contribution of this thesis is the identification of a comprehensive range of forensic weighting issues arising from the use of log evidence that concern investigators and legal authorities. This contribution is made in a comprehensive analytical discussion utilizing both the logging model and the evidential weighting criteria. The practical usefulness of the resulting evidential weighting framework is demonstrated by rigorous and systematic application to a real-world logging system.
-
ItemQoS-based scheduling of workflows on global grids( 2007-10)Grid computing has emerged as a global cyber-infrastructure for the next-generation of e-Science applications by integrating large-scale, distributed and heterogeneous resources. Scientific communities are utilizing Grids to share, manage and process large data sets. In order to support complex scientific experiments, distributed resources such as computational devices, data, applications, and scientific instruments need to be orchestrated while managing the application workflow operations within Grid environments. This thesis investigates properties of Grid workflow management systems, presents a workflow engine and algorithms for mapping scientific workflow applications to Grid resources based on specified QoS (Quality of Service) constraints. (For complete abstract open document)
-
ItemCoordinated resource provisioning in federated grids( 2007-07)A fundamental problem in building large scale Grid resource sharing system is the need for efficient and scalable techniques for discovery and provisioning of resources for delivering expected Quality of Service (QoS) to users’ applications. The current approaches to Grid resource sharing based on resource brokers are non-coordinated since these brokers make scheduling related decisions independent of the others in the system. Clearly, this worsens the load-sharing and utilisation problems of distributed Grid resources as sub-optimal schedules are likely to occur. Further, existing brokering systems rely on centralised information services for resource discovery. Centralised or hierarchical resource discovery systems are prone to single-point failure, lack scalability and fault-tolerance ability. In the centralised model, the network links leading to the server are very critical to the overall functionality of the system, as their failure might halt the entire distributed system operation.
-
ItemStigmergic collaboration: a theoretical framework for mass collaboration( 2007-12)This thesis presents an application-oriented theoretical framework for generalised and specific collaborative contexts with a special focus on Internet-based mass collaboration. The proposed framework is informed by the author’s many years of collaborative arts practice and the design, building and moderation of a number of online collaborative environments across a wide range of contexts and applications. The thesis provides transdisciplinary architecture for describing the underlying mechanisms that have enabled the emergence of mass collaboration and other activities associated with ‘Web 2.0’ by incorporating a collaboratively developed definition and general framework for collaboration and collective activity, as well as theories of swarm intelligence, stigmergy, and distributed cognition. (For complete abstract open document)
-
ItemStructured classification for multilingual natural language processing( 2007-06)This thesis investigates the application of structured sequence classification models to multilingual natural language processing (NLP). Many tasks tackled by NLP can be framed as classification, where we seek to assign a label to a particular piece of text, be it a word, sentence or document. Yet often the labels which we’d like to assign exhibit complex internal structure, such as labelling a sentence with its parse tree, and there may be an exponential number of them to choose from. Structured classification seeks to exploit the structure of the labels in order to allow both generalisation across labels which differ by only a small amount, and tractable searches over all possible labels. In this thesis we focus on the application of conditional random field (CRF) models (Lafferty et al., 2001). These models assign an undirected graphical structure to the labels of the classification task and leverage dynamic programming algorithms to efficiently identify the optimal label for a given input. We develop a range of models for two multilingual NLP applications: word-alignment for statistical machine translation (SMT), and multilingual super tagging for highly lexicalised grammars.
-
ItemScaling conditional random fields for natural language processing( 2007-01)This thesis deals with the use of Conditional Random Fields (CRFs; Lafferty et al. (2001)) for Natural Language Processing (NLP). CRFs are probabilistic models for sequence labelling which are particularly well suited to NLP. They have many compelling advantages over other popular models such as Hidden Markov Models and Maximum Entropy Markov Models (Rabiner, 1990; McCallum et al., 2001), and have been applied to a number of NLP tasks with considerable success (e.g., Sha and Pereira (2003) and Smith et al. (2005)). Despite their apparent success, CRFs suffer from two main failings. Firstly, they often over-fit the training sample. This is a consequence of their considerable expressive power, and can be limited by a prior over the model parameters (Sha and Pereira, 2003; Peng and McCallum, 2004). Their second failing is that the standard methods for CRF training are often very slow, sometimes requiring weeks of processing time. This efficiency problem is largely ignored in current literature, although in practise the cost of training prevents the application of CRFs to many new more complex tasks, and also prevents the use of densely connected graphs, which would allow for much richer feature sets. (For complete abstract open document)
-
ItemExplaining difficulties in realisation of benefits from ERP systems in developing countries( 2007)Enterprise Resource Planning (ERP) system adoptions by organizations in developing countries such as China, India, Thailand and Sri Lanka have struggled to achieve their intended benefits. The objective of this thesis is to explain why such adoptions have failed to produce intended benefits. To do this, a model is developed that integrates (a) the factors that affect realization of benefits from ERP systems in developed countries, and (b) Hayami's technology-transfer model. With respect to the latter, Hayami argues that misfits related to three factors - culture, institutions, and resources – often inhibit effective adoption of imported technologies in developing countries. The contribution of this thesis is the theoretical model developed using literature and empirical data from the seven in-depth case studies, four in Sri Lanka and three in three developed countries (Australia, Canada and Sweden). No prior published study has proposed a mechanism through which country-contextual factors such as culture and institutions lead to reduced organizational benefits from ERP systems in organisations in developing countries. The mechanism proposed in this study is that (a) misfits between deeply rooted factors such as culture, institutions and resources on the one hand, and assumptions impounded in the western-developed software on the other, often reduce the level or outcomes for the benefit drivers such as ERP module integration, functional fit, and effective use, and (b) that these less-than-desired outcomes, in turn, lead to reduced benefits from ERP systems for organizations in developing countries. By opening up what has hitherto been a "black box" relationship between culture, institutions, and resources on the one hand, and reduced organizational benefits from ERP systems on the other, the model proposed in this thesis lays a foundation for theory testing and further research.
-
ItemA conceptual framework for situated task analysis within the context of Computer-Assisted Language Learning system design( 2007)This thesis examines the role of Human-Computer Interaction (HCI) task analysis within the context of Computer-Assisted Language Learning (CALL) system design. It recognises and critically examines several carrefours that differentiate cognitive from sociocultural task analysis theories in Second Language Acquisition and Human-Computer Interaction. A study into the role of multimodal interaction and second language (L2) vocabulary acquisition revealed the need for an integrative approach to examining learner-computer interaction. In response, a conceptual, situated task analysis framework was developed that promotes (1) a common unit of analysis for principled theoretical investigation and methodological selection; and (2) a formative task analysis framework which considers both software engineering and human-computer interaction practices within CALL system design. Understanding the extant relationships between learner, theory and practice has become increasingly important in light of recent criticisms of CALL software quality, and its influence on learning outcomes. To further develop our understanding of the role of HCI and Software Engineering in CALL, an empirical exploratory study was undertaken. The design of the study was influenced by research concerning (1) cognitive complexity and language learning; (2) social perspectives on learner-computer interaction; and (3) the intersection between system design, quality, and learner-computer interaction. Computer-mediated activity in language learning environments can be categorised as a highly social process through its dependency upon a number of sociocultural and environmental contraints. As such, learner-computer interaction is likely to be highly fluid and dynamic. The distinction between static and dynamic environments is a critical determinant when selecting a particular HCI task analysis strategy. To evaluate competing task analysis approaches, a small qualitative study was established that considered the role of multimodal interaction in L2 vocabulary acquisition. Emerging trends from this study served to elucidate the appropriateness of existing HCI theories and their units of analysis within the context of CALL system design. Participants for this study were selected from an undergraduate Computer Science degree at a major Australian university. Participants had little to no prior knowledge of the L2 used in the study. Participants conducted three sessions with a multimodal speech-enabled language learning tool. After each session, participants completed an immediate recall test and responded to a series of semi-structured interview questions. After an eight week period, participants were asked to take part in a delayed recall and recognition test. Findings from this study showed two distinct trends: (1) a relationship between the degree of multimodal interaction strategy and delayed L2 vocabulary recall and recognition; and (2) the limitations of existing HCI task analysis approaches with respect to analysing learner-computer interaction within the context of CALL system design. As such, this study provided key insights into the role of HCI in CALL, proposing several implications for further research. Instructed by these findings, research was undertaken to develop an holistic, situated task analysis framework: C.A.S.E (Cognition, Activity, Social Organisation, Environment). Ontological, epistemological and methodological components of the framework are discussed in detail. C.A.S.E provides a conceptual framework for integrating cognitive and social theories on learning, interaction and system design. Consequently, C.A.S.E provides both theoretical and methodological support for bridging the divide between CALL, HCI and Software Engineering. Several applications of the framework relevant to CALL practitioners are described in this thesis. The outcomes of this investigation establish an agenda for further research. The thesis concludes with a discussion related to CALL system design, specifically the role of Software Engineering in end-user developer CALL activities. To assist readers, additional discussions on Philosophy of Science and Software Engineering have been provided as appendix chapters.