The main aim of this research project is to investigate the relationship between students and their electronic learning environments, and in particular, how eLearning spaces influence and are influenced by the adaptable and adaptive learning attitudes of the new student generation. In particular, it focuses on what I defined as digital students as young adult students who have grown up with active participation in technology as an everyday feature of their lives. The characteristics of the technologically confident digital students were found to include a strong need for instantaneity, a desire to control their environment and to channel their social life via extensive use of technology.

The population of high-spin isomeric states in neutron-deficient N≈126 nuclei has been studied in order to further understand the reaction mechanism of projectile fragmentation. The nuclei of interest were populated following projectile-fragmentation of a 1 GeV/A 238U beam on a 9Be target at GSI, Germany. The reaction products were selected and separated in the FRS FRagment Separator and brought to rest in an 8 mm plastic stopper placed at the focus of the RISING gamma-ray detector array. The results on the development of an add-back method for the RISING array are presented and discussed for source and in-beam data.

This work arises from a hepatitis C cohort study and focuses on estimating the effects of covariates on progression to cirrhosis. In hepatitis C cohort studies, patients may be recruited to the cohort with referral bias because clinically the patients with more rapid disease progression are preferentially referred to liver clinics. This referral bias can lead to significantly biased estimates of the effects of covariates on progression to cirrhosis.

This thesis describes a method of identifying the influences on schedule delays in projects that develop large software systems. Controlling schedule duration is a fundamental aspect of managing projects because of the financial losses associated with late projects. While challenges with controlling software projects have been investigated, there still seemed to be more to be learned about the interplay of a range of factors during project execution and that affect project duration when developing and integrating software systems within enterprise architecture environment.

The objective of this thesis is to improve battlefield communications capability through improved management of existing platform and fleet level resources. Communication is a critical capability for any platform node deployed on a modern battlefield and enables vital Network Enabled Capabilities (NEC). However, the dynamicity and unpredictability of wireless battlefield networks, as well as the constant threat of equipment damage make wireless battlefield networks inherently unreliable and as such the provision of a stable communication represents a significant technology management challenge. Fulfilling increasingly complex communications requirements of diverse platform types in a chaotic and changing battlefield environment requires the use of novel Resource and Capability Management Algorithms (RCMA) informed by application level context data to manage limited heterogeneous resources at the platform and the fleet level while fulfilling current mission goals.

Taking a problematic user experience with ubiquitous annotation as its point of departure, this thesis defines and explores the design space for Social Object Labels (SOLs), small interactive displays aiming to support users' in-situ engagement with digital annotations of physical objects and places by providing up-to-date information before, during and after interaction. While the concept of ubiquitous annotation has potential applications in a wide range of domains, the research focuses in particular on SOLs in a museum context, where they can support the institution's educational goals by engaging visitors in the interpretation of exhibits and providing a platform for public discourse to complement official interpretations provided on traditional object labels. The thesis defines and structures the design space for SOLs, investigates how they can support social interpretation in museums and develops empirically validated design recommendations. Reflecting the developmental character of the research, it employs Design Research as a methodological framework, which involves the iterative development and evaluation of design artefacts together with users and other stakeholders. The research identifies the particular characteristics of SOLs and structures their design space into ten high-level aspects, synthesised from taxonomies and heuristics for similar display concepts and complemented with aspects emerging from the iterative design and evaluation of prototypes. It presents findings from a survey exploring visitors' mental models, preferences and expectations of commenting in museums and translates them into requirements for SOLs. It reports on scenario-based design activities, expert interviews with museum professionals, formative user studies and co-design sessions, and two empirical evaluations of SOL prototypes in a gallery environment. Pulling together findings from these research activities it then formulates design recommendations for SOLs and supports them with related evidence and implementation examples. The main contributions are (i) to delineate and structure the design space for SOLs, which helps to ground SOLs in the literature and understand them as a distinct display concept with its own characteristics; (ii) to explore, for the first time, a visitor perspective on commenting in museums, which can inform research, development and policies on user-generated content in museums and the wider cultural heritage sector; (iii) to develop empirically validated design recommendations, which can inform future research and development into SOLs and related display concept. The thesis concludes by summarising findings in relation to its stated research questions, restating its contributions from ubiquitous computing, domain and methodology perspectives, and discussing open issues and future work.

Constraint diagrams are part of the family of visual logics based on Euler diagrams. They have been studied since the 1990s, when they were first proposed by Kent as a means of describing formal constraints within software models. Since that time, constraint diagrams have evolved in a number of ways; a crucial re- finement came with the recognition of the need to impose a reading order on the quantifiers represented by diagrammatic syntax. This resulted first in augmented constraint diagrams and, most recently, generalized constraint diagrams (GCDs), which are composed of one or more unitary diagrams in a connected graph. The design of GCDs includes several syntactic features that bring increased expressivity but which also make their metatheory more complex than is the case with preceding constraint diagram notations. In particular, GCDs are given a second order semantics.

The thesis investigates ion behaviour at collisionless shocks, with a focus on two areas of interest. The first area concerns the reflection of particles from collisionless shocks, a necessary mechanism for thermalization at a shock at sufficiently high Mach numbers such as ordinarily prevail at the Earth's bow shock. Previous studies have examined the trajectories of reflected ions with the assumption of a planar shock. In this study, a general framework is developed to describe the trajectory of an ion after reflection, with application to a variety of shock geometries. The conditions allowing an ion to return to the shock after reflection and to return with an increased normal velocity are studied, with three primary parameters considered: the radius of curvature, the magnetic field orientation, and the incident velocity in the shock normal direction. Each of these parameters depends on the shape of the shock and the location of incidence. Results are reported for cylindrical, spherical, and parabolic shock geometries, over ranges of shock curvatures, magnetic field orientations, and incident velocities. Second, we consider the thermalization of the ion distribution initially transmitted through the shock under low Mach number conditions, where reflection is a less significant contributor to thermalization. Previous work has considered the phase area invariant in an exactly perpendicular case. This is generalized to a quasi-perpendicular shock, and invariants of the flow are determined for a Hamiltonian formulation. The evolution of the distribution through the shock is then studied analytically and numerically. Results regarding the shape of phase shells of constant probability, the phase volume within these shells, and the temperature of the distribution are given.

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Symbolic execution is a well-established technique for automated test generation and for nding errors in complex code. Most of the focus has however been on programs that manipulate integers, booleans, and even, references in object-oriented programs. Recently researchers have started looking at programs that do lots of string processing, motivated, in part, by the popularity of the web and the risk that errors in web servers may lead to security violations. Attempts to extend symbolic execution to the domain of strings are mainly divided into one of two camps: automata-based approaches and approaches based on bitvector analysis. Here we investigate these two approaches in a uni ed setting, namely the symbolic execution framework of Java PathFinder. We describe the implementations of both approaches and then do an evaluation to show under what circumstances each approach performs well (or not so well). We also illustrate the usefulness of the symbolic execution of strings by nding errors in real-world examples. / AFRIKAANSE OPSOMMING: Simboliese uitvoering is 'n bekende tegniek vir automatiese genereering van toetse en om foute te vind in ingewikkelde bronkode. Die fokus sover was grotendeels op programme wat gebruik maak van heelgetalle, boolse waardes en selfs verwysings in objek geörienteerde programme. Navorsers het onlangs begin kyk na programme wat baie gebruik maak van string prosessering, deelteliks gemotiveerd deur die populariteit van die web en die gepaardgaande risiko's daarvan. Vorige implementasies van simboliese string uitvoering word binne twee kampe verdeel: die automata gebaseerde benadering en bitvektoor gebaseerde benadering. Binne hierdie tesis word die twee benaderings onder een dak gebring, naamliks Java PathFinder. Die implentasie van beide benaderings word bespreek en ge-evalueer om die omstandighede uit te wys waarbinne elk beter sou vaar. Die nut van simboliese string uitvoering word geïllustreer deur dit toe te pas in foutiewe regte wêreld voorbeelde.

A Tutte trail T of a graph G is a trail such that every component of GnV (T) has at most three edges connecting it to T. In 1992, Bill Jackson conjectured that every 2-edge-connected graph G has a Tutte closed trail. In this thesis, we show that Jackson's conjecture is true when G is embedded on the plane and the projective plane. We also give some partial results when G is embedded on the torus.