A general system for controlling an unknown process by adjusting compensation networks is discussed. The control operation is divided into two parts, that of identification of the unknown process dynamics and that of adaption by adjusting the compensation networks. Both operations are carried out by the method of steepest descent, using a suitable error signal as a performance function. A general method of investigation is considered, which is applicable to all systems of this type. The systems are classified as Type I and Type II; it is shown that a Type I system is stable for all input signals and initial conditions. The systems which are not of Type I are designated as Type II and it is shown that the behaviour of Type II systems can be approximated by that of a Type I system in the neighbourhood of the optimum point of operation. These results are applied to investigating the behaviour of a number of controllers and identification systems. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The inter-relation of phenomena on the sun and in the earth's ionosphere has been studied in order to establish a causal dependence which could result from travelling solar particles. In addition to examining a variety of data from a number of sources, an extensive R.F. noise recording program was undertaken to provide information on those regions of the solar and terrestrial atmospheres from which optical data were not available. The occasions on which there was an influx of such particles into the earth's ionosphere were established from magnetic data, from optical observations of the Polar Aurora, and from H.F. and V.H.F. radio observations close to the Auroral Zone. On the basis of these data the ionospheric disturbances for a 12 month period were related to prior distinctive solar events that were considered capable of producing the high energy particles. The selection was made from the optical, spectroscopic and radio data available. It was found that solar flares, eruptive prominences, and disappearing filaments were the most frequent sources of Earth-reaching particles, and that large sunspots contributed only occasionally to ionospheric disturbances. Moreover, the radio noise data permitted a fairly reliable estimate of the particle velocities in the solar corona, which could be used to predict the probability of subsequent terrestrial effects of the ejected particles. A correlation coefficient of +0.65 was found between probabilities predicted from the solar information and observed ionospheric disturbances which occurred two or three days later. The observational evidence on the solar noise bursts and on ionospheric storms could only be explained on the basis of a considerable distribution of velocities for the particles ejected from the sun. It was shown that a Maxwellian distribution of corpuscular velocities was a probable one. Moreover, the observations indicated that particles are frequently emitted from the sun with a distribution of velocities, but that only in the case of very large phenomena are there sufficient particles with the high energies necessary to overcome the sun's gravitational field and reach the earth. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis deals with the identification of parameters in distributed parameter systems. Two sensitivity methods, namely; Meissinger's method and the method of structural sensitivity are extended to obtain the sensitivity coefficients of discretized distributed parameter systems. The method of Bingulac and Kokotovic is extended to identify parameters in the one and the two dimensional parabolic differential equations. CSMP (continuous system modeling programme) is used throughout to simulate the systems. Results for both sensitivity schemes are obtained, and it is found that although structural sensitivity is advantageous for parameter identification in ordinary differential equations, this is not the case for partial differential equations. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The case study afforded an opportunity to demonstrate how divergent opinions of various stakeholders could be harnessed and synthesised to provide input to resolve perceived problematical situations. In the case study of the hard systems method, ISM, divergence of the stakeholder views was through the process intended to achieve convergence (consensus) in order to solve the problem situation. In the case of the soft systems method, SSM, divergence of views were synthesised to produce an all embracing solution Of the perceived situation. No attempt is made to produce consensus. Systems thinking, therefore, is able to deal with issues that have given known-to-be desirable ends (hard systems) and where known-to-be desirable ends (soft systems) cannot be taken as given. This research has attempted to address the issue of managing the complexity of development in the context of the recently democratised South Africa. It has basically suggested that, as a point of departure, developmental issues should be approached holistically and systematically. It is important to select an appropriate methodology in seeking to solve the problem of managing change. The quality of the outcome of the two case studies reviewed has been affected by the quality of the inputs, particularly with respect to availability of time, availability of stakeholder inputs and the status of the research (that is, as an academic exercise).

In recent years, given the increased investments in Information Technology (IT), and its pervasive usage in business environment, the need to ensure that IT decisions are in the interest of shareholders led practitioners and researchers to focus on Enterprise Governance of IT (EGIT). EGIT involves implementing mechanisms that ensure that IT risks are duly mitigated, and that the IT investments are yielding the expected returns for enterprise owners. For the mechanisms to work as intended, there is the need for regular auditing; however, past literature and practitioner reports have confirmed that auditors do not audit governance mechanisms to the expectation of shareholders. Within the Ghanaian Financial services sector, failures in EGIT resulted in the collapse of several organisations which made stakeholders question the role played by auditors. The purpose of this study was to examine EGIT from the perspective of the auditor, develop an audit framework based on COBIT 5 and understand how auditors can be 'critical partners’ to ensure EGIT effectiveness. To provide a better understanding of the EGIT phenomenon, a theoretical framework based on the integration of six theoretical perspectives was presented to provide a holistic view of EGIT and how auditors can add value. The theoretical framework argued in line with organisational theorists that to achieve positive outcomes, governance mechanisms must be implemented in a coherent whole and analysed as a configuration. As such the study adopted the configurational theory to analyse the coherence of the governance mechanisms. Based on the theoretical framework and the configurational theory, a conceptual framework was developed to guide the research. The thesis proposed that the greater the level of coherence among the governance mechanisms, the higher the level of EGIT effectiveness, and that the audit of EGIT will improve the maturity of the governance mechanisms and its coherence. The pragmatic philosophic stance was adopted, utilising qualitative and quantitative methods to answer the research question. The Peffers, Tuunanen, Rothenberger, & Chatterjee, (2008) design science research methodology guided the identification of the problem and the development of an artefact that can aid IT auditors by providing them with an adequate scope for EGIT audits and reduce the audit detection risks. An Exploratory Focus Group (EFG) and a Confirmatory Focus Group (CFG) were employed in the development of the artefact. In addition, a survey instrument was utilised to gather data about the governance maturity of the case organisations prior to and after the usage of the artefact. Cluster analysis based on the concept of 'coherence as a gestalt’ produced cluster solutions revealing the nature of the configuration that resulted in positive outcomes. Post-Hoc analysis was used in the summative evaluation of the artefact to measure the statistically significant changes that occurred in the governance maturity after the use of the artefact. The findings revealed that regular auditing of EGIT mechanisms can lead to significant improvement in several governance mechanisms as postulated. It also revealed that to attain positive outcomes, there is the need for a coherent implementation of governance mechanisms with emphasis on technology which can be the driving force in a fast-changing environment. This result was contrary to existing literature about EGIT that suggested the overarching importance of leadership to drive change in the attainment of EGIT objectives. The findings show that with the right systems and technologies, IT can provide decision makers with timely information that would increase the utility of the decisions. The study makes significant contributions to knowledge by providing insights into EGIT and IT auditing which is an under-researched area. One key theoretical contribution was the integrative theoretical framework that provides theoretical underpinnings to EGIT, which has previously been studied descriptively and provides a holistic view of the complex phenomenon. The study also confirms the configurational theory and advances knowledge by proving that in the context of EGIT, the combination of the various mechanisms does influence the whole and the outcomes. Concerning the contribution to practice, the study resulted in the development of an IT auditing artefact that is based on COBIT 5, a widely accepted industry framework for EGIT, and contextualised with the regulatory needs of the Ghanaian Financial Services sector. With this tool, IT auditors can develop an audit plan that provides assurance of key governance areas and so reduce the audit risk of not detecting a non-existence or weak control in an organisation’s EGIT practices. The tool can be used by regulatory auditors who were complicit in the EGIT failures that occurred in the sector to provide adequate supervision. Further discussion on the theoretical, practical and methodological contributions are set out in this thesis along with the limitations of the study and recommendations for future research.

Information Technology (IT) has become indispensable in contemporary business processes and in business value creation strategies. Those charged with governance, risk management and compliance are, often, challenged by sophisticated IT oriented decision-making dilemmas due to complex IT use in contemporary business processes. Investors and other stakeholders increasingly expect very rich, reliable and transparent assurance that their interests are safe. Auditors, as a result, are looked upon to expand their role to leverage the functions of those charged with governance and management. IT audit literature, hence, demonstrates existence of several best practices aimed at meeting the increasing demand for more audit and assurance outcomes that bridge the widening audit expectations gaps. In developing countries with less stringent regulatory systems, however, attempts to implement many of these frameworks have proved unsuccessful. Reasons include paucity of guidance in the frameworks and lack of suitable theoretical foundations to resort to for solutions to implementation challenges. Extant literature review reveals scanty research effort by practitioners or academicians in the field in the empirical situation to design a more suitable framework to serve as intervention. In this research an attempt has been made to create an intervention by designing a framework, i.e. an artefact for IT auditing for less regulated business environments. By adductive inference the cybernetics theory of viable systems approach was ingrained as the theoretical foundation from which the variables for the design were extracted. The abduction was based on the diagnostic power and ability to support self-regulation in a less regulatory environment. Action design research (ADR) approach was employed to achieve the research objective. Both qualitative and quantitative techniques were found to be useful for the evaluation and data analysis. At the design phase, a multiple case study method together with workshops were employed to gain insight into the problem and to collect data to support the design process. Four organisations from both public and private sectors in Ghana were selected to participate in the research. At the evaluation stage a survey technique was used to collect data mainly for the validation of construct variables and the refinement of the framework. The questionnaire scale used was 1=Strongly Disagree; 2=Disagree; 3=Somewhat Agree; 4=Agree and 5=Strongly Agree. A total of 136 respondents who included IT audit and Internal audit practitioners, Audit trainees and students, Directors and management staff were involved from four selected organisations. A factor analysis yielded twenty variables extracted from the ingrained theory for the building of a conceptual model which were grouped into six factors or domains. The entire conceptual model was tested with PLS-SEM technique because of the causal relationships that motivated the development of the conceptual hypotheses. A composite reliability used to assess the internal consistency of the model was overall adequate with values greater than 0.7. Similarly, a convergent validity of the model showed that all the variables were above the threshold value of 0.5. Thus, the model and design theory were found to be reliable and valid. Correlation and regression analysis was applied in testing individual hypotheses and the results helped to reorganise the final framework. The study contributed an artefact in the field of IT audit which represents a comprehensive teachable practitioner’s guide for the improvement of the IT audit practice. The framework also serves as guidance to those charged with governance and management in monitoring, self-review and as framework to attain IT audit readiness in less regulatory environments. Implementation challenges are expected to be resolved by reverting to the ingrained theory.

Health systems, like commercial enterprises, face wide-ranging challenges and need to develop an adaptive capacity in order to remain effective. There is increasing recognition in the health sector that the concept of the learning organisation, which has long been popular in the business management field, could be a key strategy to develop this adaptive capacity in health systems. Although examples exist of the application of learning organisation principles to health care facilities, there is little guidance for how units or groups responsible for health policy and strategies can apply them more widely. In order to provide some initial guidance to the Western Cape Department of Health, which has expressed an interest in developing into a learning organisation, this project sought to identify the enablers of, and barriers to learning organisation creation by conducting a systematic review of learning organisation interventions across multiple sectors. As multiple definitions and models of a learning organisation exist in the literature, this systematic review was complemented by an initial review of conceptual literature which synthesised the existing definitions and models of a learning organisation and identified a core set of learning organisation dimensions. Findings indicate that a foundation of good organisational software such as a shared understanding of, and commitment to a learning organisation vision, a culture which is conducive to learning organisation creation, and a secure, supportive and interpersonally non-threatening environment, is essential for learning organisation creation. Building on this foundation it is then important to invest in staff time (i.e. that staff are officially allowed, and incentivised, to spend time on learning during work hours), and the infrastructure and processes necessary to support knowledge transfer, such as physical meeting spaces, online learning databases, mentorship programmes, and feedback mechanisms.

Current Social Networking Systems (SNS) such as YouTube are creator-driven systems in which creators create content and users search among available content to find what they want. However, queries from users can be time-sensitive, such as some real-time hot topics, which are difficult to obtain at the very moment due to their timeliness and dynamically changing nature. To address this situation, we quest if the system can directly let a user input a query, match the most relevant users (receivers) based on the query and let the receivers decide whether to respond with the very content. In this way, the user can obtain the most relevant data through highly relevant receivers while reducing the reliance on the system's existing data in the recommendation process as an alternative, a new query-driven SNS paradigm. The main objective is to target the most relevant receivers based on a query. In this case, we propose that by allowing users to provide their very moment ideas as queries, the system searches and ranks well-targeted users based on the semantic content of the query and existing user features. However, the user's feature might be incomplete or missing. To alleviate this issue, we propose a novel two-stage query-driven graph-based user recommender system (QDG) that supports query-to-user matching with dynamic update capabilities. In the first stage, we encode the query and item descriptions into attribute features and perform a similarity search to target the Top-N candidate items. In the second stage, we propose a temporal-based graph neural network (t-GNN), which combines the inductive learning-based GNN with the self-attention-based temporal analysis module to predict the most relevant user-item interaction by simultaneously extracting the existing Spatio-temporal features, where spatial feature represents user's relationship with items and temporal feature represents user's behaviour information. We conducted recommendation simulations on six million users and 150,000 merchants on North America YELP data. Experiments show that the QDG system can accurately target strongly relevant users in the North American population based on the query. To the best of our knowledge, we are the first to propose query-driven SNS and demonstrate its effectiveness in a million-scale Yelp dataset.

Recently it has been shown that leukocytes are capable of producing prolactin (PRL). Evidence of extra-pituitary PRL (ePRL) production is so far been limited to primates and is not shared across other mammal species such as mice and rats. While ePRL is characterized as an identical protein to traditional pituitary PRL, it is controlled under an alternative promoter and is thus regulated differently from pituitary PRL. Little is known about what regulates ePRL or its direct role in human physiology, but given that PRL has well over 300 described functions, it is likely that the autocrine and paracrine effects of this hormone could have far reaching implications in overall physiology. This work takes some of the first steps in understanding how leukocyte ePRL is regulated. Our results show that, adrenergic hormones are one key stimulus in ePRL expression in monocytes/macrophages. This is particularly intriguing considering the opposing role of these two signals in settings such as adipose tissue where adipose tissue macrophages are constantly exposed to pro-lipolytic adrenergic hormones that would in turn stimulate production of an anti-lipolytic hormone, PRL. Further, our work shows that the inflammatory phenotype of the leukocytes influences basal expression of PRL and overall ePRL expression increases significantly as monocytes differentiate into macrophages, as is a common occurrence in adipose tissue. The final portion of our work shows how monocytes/macrophages also respond to preadipocytes directly. These stem cell precursors to mature adipose cells release an unknown factor that stimulates ePRL production in monocytes/macrophages. Analysis of our gene array shows many of the genes stimulated by adipose stem cells alongside PRL are important genes in tissue regeneration and remodeling, a possible role that fits well with known effects of PRL. Understanding such primate specific interactions between the immune system and major metabolic tissues such as adipose fills vital gaps in knowledge that may explain why so many treatments fail when transitioning from mouse models to humans.

With the advent of large and complex applications and the emergence of semi-structured information repositories such as the World Wide Web, new demands are being made on database systems. The TENTACLE database system is an experimental database system which provides facilities capable of meeting some of these demands. The distinguishing features of the system are that it: uses a graph-based data model (and storage subsystem) to provide a flexible means of representing poorly structured information, integrates a path expression-based query language with a general purpose language to query and manipulate the graph structures, thereby eliminating the impedance mismatch encountered in a two language system, and provides a programmable database kernel capable of executing the combined query and utility language, allowing the construction of domain specific applications inside the database without the assistance of wrappers or gateways. As a demonstration of the utility of the system, I have constructed a hypertext server inside the TENTACLE database without making use of external mediators or gateways. Since the hypertext server program is part of the database content, database facilities may be used to assist in the creation and maintenance of the hypertext server itself. In addition, the close integration of hypertext server and database simplifies tasks such as the management of associations between hypertext entities or the maintenance of different document views.