African Journals Online
South African Computer Journal / Die Suid-Afrikaanse Rekenaartydskrif

Issue 28, June 2002
Abstracts

An access control architecture for XML documents in workflow environments : research article

Botha, R.Eloff, J.

Abstract: The eXtensible Markup Language (XML) are being upheld as having the potential to change the way business is conducted. This will be e(r)ected by changing the way in which information is shared. However, with the sharing of information, information security becomes a concern. This paper presents an access control architecture that allows for the sharing of XML documents in workflow environments. The architecture addresses the issue of access control from two perspectives. On the one hand, issues regarding the confidentiality of information are addressed. On the other hand, the semantic integrity of information is attended to. The paper shows how the access control services, provided as part of the architecture, achieve these objectives.

Combining context provisions with graph grammar rewriting rules - the three-dimensional case : research article

Barnard, A.Ehlers, E.M.

Abstract: In this paper we consider the representation and generation of three-dimensional structures by means of formal descriptive methods. Graph and graph grammar theory present us with a powerful two-dimensional representational method, and we propose to use these concepts as basis for the three-dimensional case. Three-dimensional structures however, often appear in other structures and within a certain context. This context may be defined or influenced by the overall structure, or other related structures. We therefore need to be cognisant of the role that these contexts play when we introduce the concepts of three-dimensional graph and graph grammar systems, with particular reference to contextual rewriting rules. It is the combination of context provisions with graph grammar rewriting rules that results in a formal descriptive method which represents three-dimensional structures. The generative abilities of the concepts we introduce and discuss, are illustrated by considering the generation of various chemical structural formulae.

Creating high performance IS teams : research article

Smith, D.C.Becker, M.Burns-Howell, J.Kyriakides, J.

Abstract: The use of teams within organisations is becoming more prevalent as teams have been identified as an efficient work unit of human capital. This research identified 17 team effectiveness characteristics and, using a sample of local project team members, attempted to ascertain which of these factors distinguished highly performing IS teams from lower performing ones. A web-based survey was conducted and valid data collected from 62 IS professionals working in project teams. The results suggested that Goal Setting, Conflict Management, Skill Diversity/Heterogeneity, Commitment, Quality and Performance, Mutual Accountability, Trust and Support were significant characteristics in segregating high performance IS teams from those who achieved lower performance levels. These findings are of use to IS project managers who need to focus on all the 17 characteristics whilst placing particular emphasis on the 6 characteristics reported above.

Finite-state computational morphology - treatment of the Zulu noun : research article

Pretorius, LBosch, S.E.

Abstract: Morphological analysis is a basic enabling application for further kinds of natural language processing, including part-of-speech tagging, parsing, translation and other high-level applications. Automated morphological analyzers exist for many of the European languages, but have not been reported for any of the indigenous languages of southern Africa. Our project in computational morphological analysis/generation includes the production of an automated morphological analyzer/generator for Zulu, using finite-state methods and tools. In this paper we elaborate on the use of finite-state methods in computational morphology, and report on our treatment of the Zulu noun.

Implication in three-valued logics of partial information : research article

Britz, K.

Abstract: In formal logic, both semantic entailment and the conditional connective are used to formalize the intuitive notion of implication. The former is defined in the meta-language of the logic, and the latter in the language of the logic. Their interaction determines to what extent the conditional connective relates to entailment as an implication should. This paper addresses this question for a number of related three-valued logics based on Kleene's strong truth tables, and defines a suitable implication for Partial Logic.

Information systems strategic planning and IS function performance : an empirical study : research article

Cohen, J.F.

Abstract: The validity of managerial activities such as strategic planning has come under increasing scrutiny in recent years. In particular, the validity of information systems strategic planning (ISSP) within South African organisations remains to be demonstrated by empirically confirming its link to IS performance measures. This paper presents findings from an empirical study of ISSP involving responses from 100 listed public companies. Results indicate that emphasis placed on ISSP activities, planning commitment and integration mechanisms are significantly related to IS function performance. More successful IS functions were found to place more emphasis on ISSP activities, to commit greater resources to ISSP and to attribute greater importance to the integration of ISSP and business strategic planning processes, than poor performing IS functions. Planning experience was not found to moderate the relationships.

Model-based segmentation of CT images : research article

Marte, O-C.Marais, P.

Abstract: This paper presents preliminary work on the segmentation of Computed Tomography data using a model-based approach. Conventional image processing of CT data is aimed at the production of simple iso-surfaces for surgical planning or diagnosis - such methods are not suitable for the automated detection of fractures, which is the ultimate application of our work. To address these deficiencies a surface-based technique with appropriate constraints is introduced. The output of the segmentation phase is a triangulated surface representing the bone or bones of interest. We illustrate the method applied to low resolution CT test data and discuss its robustness and performance.

Structured educational design and modelling for digital courses : research article

Cloete, E.Miller, M.G.

Abstract: Today there seems to be a tremendous interest in e-learning, and in particular Web-based education. There also seems to be a lot of experimentation with e-learning. However, despite the interest, experimenting, research and the potentials of virtual learning, it also seems that the implementation of e-learning systems has not been as indicative as the advancement of technology allows. Although the reasons for this lack of full-scale successful implementations and continuation of e-learning programmes often differ amongst institutions, standardizing electronic educational processes is a prerequisite to successfully enter the market of e-learning. In this paper we consider the consequences of e-learning design and implementation on the working processes and on the roles to be fulfilled in the usually cyclic process of course development and -exploitation. We analyse generic course design according to the principles of competence-oriented education and present a framework in which digital learning systems can be designed and implemented in such a way that it is possible to maintain course quality, reuse course components and simplify course maintenance.

Ubiquitous computing and cellular handset interfaces - are menus the best way forward? : research article

Marsden, G.Jones, M.

Abstract: Embedded interactive computer systems, such as those found in cellular handsets, can be hard to use. The combination of small form factor limited input and output potential and an increasing feature set, result in devices which confuse novice users. Although most of these devices utilise hierarchical menu structures to mediate the interaction between user and device, we believe that these menus are poorly designed and that other interaction styles may be more appropriate. In this paper we will investigate how well menu design research has been used by current handset manufacturers. We will also propose and report on the success of some new interface designs and finally examine how new Internet technologies, like WML, might be used to further improve the handsets interface.