Thesis (MSc (Mathematical Sciences)--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In this thesis, a pricing mechanism to stimulate cooperation between nodes in ad hoc networks is explored. The model incorporates incentives for users to act as transit nodes and carry the traffic between other nodes on multi-hop paths, and to be rewarded with their own ability to send traffic. The thesis investigates the consequences of this pricing model by means of simulation of a network and illustrates the way in which network resources are allocated to users according to their geographical position. Moreover, since modelling node movements is an important aspect in ad hoc network simulation, a collective mobility model, the adaptive mobility model, is used to maximise the area coverage of the nodes. / AFRIKAANSE OPSOMMING: In hierdie tesis word ’n koste meganisme gebruik om samewerking te stimuleer tussen nodusse in ad hoc netwerke. Die model inkorporeer trekpleisters deur gebruikers te beloon om verkeer te stuur deur op te tree as transito nodusse, en verkeer tussen nodusse op multi-skakel paaie te dra. Die tesis ondersoek die ge- volge van die koste model deur die simulering van ’n netwerk, en demonstreer die manier waarop die netwerk hulpbronne geallokeer word aan gebruikers gebaseer op hulle geografiese posisie. Siende dat die modellering van nodus bewegings ’n belangrike aspek is in ad hoc netwerk simulasie, word ’n kollek- tiewe mobiliteits model sowel as ’n veranderlike mobiliteits model gebruik om die dekkings areas van die nodusse te maksimeer.

Thesis (MComm)--University of Stellenbosch, 2003. / Please refer to full text for abstract.

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Network simulations generate large volumes of data. This thesis presents an animated visualization system that utilizes the latest affordable Computer Graphics (CG) hardware to simplify the task of visualizing and analyzing these large volumes of data. The use of modern CG hardware allows us to create an interactive system which allows the user to interact with the data sets and extract the relevant data in real time. We also present an alternate approach to the network layout problem, using Self Organizing Maps to find an aesthetic layout for a network which is fundamental to a successful network visualization. We finally discuss the design and implementation of such an network visualization tool. / AFRIKAANSE OPSOMMING: Netwerk simulasies genereer groot volumes data. Hierdie tesis stel voor ’n geanimeerde visualiseringwat gebruik maak van die nuutste bekostigbare rekenaar grafika hardeware om die visualisering van groot volumes data te vergemaklik. Die gebruik van moderne rekenaar grafika hardeware stel ons in staat om sagteware te skep wat n gebruiker in staat stel om met die data te werk. Ons stel voor ’n alternatiewe benadering om die netwerk se uitleg daar te stel, met die hulp van tegnieke wat gebruik word in die studie van neurale netwerke. Ons bespreek dan die ontwerp en implementering van so ’n netwerk visualisering program.

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Program slicing was originally described by Mark Weiser in 1984. He proposed this as a technique to aid in debugging because he conjectured that this is what programmers did naturally when debugging. Here program slicing is applied to an experimental concurrent language called LF. Existing techniques are adapted to accommodate the unique features of the language. / AFRIKAANSE OPSOMMING: Programdeling is oorspronklik deur Mark Weiser beskryf in 1984. Hy het dit voorgestel as ’n tegniek om ontfouting te vergemaklik, want hy het geglo dat dit is wat programmeerders van nature self doen. Programdeling word hier toegepas op ’n eksperimentele gelyklopende taal genaamd LF. Bestaande tegnieke word gewysig om die taal se unieke eienskappe in ag te neem.

Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Machine translation, especially machine translation for sign languages, remains an active research area. Sign language machine translation presents unique challenges to the whole machine translation process. In this thesis a prototype machine translation system is presented. This system is designed to translate English text into a gloss based representation of South African Sign Language (SASL). In order to perform the machine translation, a transfer based approach was taken. English text is parsed into an intermediate representation. Translation rules are then applied to this intermediate representation to transform it into an equivalent intermediate representation for the SASL glosses. For both these intermediate representations, a tree adjoining grammar (TAG) formalism is used. As part of the prototype machine translation system, a TAG parser was implemented. The translation rules used by the system were derived from a SASL phrase book. This phrase book was also used to create a small gloss based SASL TAG grammar. Lastly, some additional tools, for the editing of TAG trees, were also added to the prototype system. / AFRIKAANSE OPSOMMING: Masjienvertaling, veral masjienvertaling vir gebaretale, bly ’n aktiewe navorsingsgebied. Masjienvertaling vir gebaretale bied unieke uitdagings tot die hele masjienvertalingproses. In hierdie tesis bied ons ’n prototipe masjienvertalingstelsel aan. Hierdie stelsel is ontwerp om Engelse teks te vertaal na ’n glos gebaseerde voorstelling van Suid-Afrikaanse Gebaretaal (SAG). Ons vertalingstelsel maak gebruik van ’n oorplasingsbenadering tot masjienvertaling. Engelse teks word ontleed na ’n intermediˆere vorm. Vertalingre¨els word toegepas op hierdie intermediˆere vorm om dit te transformeer na ’n ekwivalente intermediˆere vorm vir die SAG glosse. Vir beide hierdie intermediˆere vorms word boomkoppelingsgrammatikas (BKGs) gebruik. As deel van die prototipe masjienvertalingstelsel, is ’n BKG sintaksontleder ge¨ımplementeer. Die vertalingre¨els wat gebruik word deur die stelsel, is afgelei vanaf ’n SAG fraseboek. Hierdie fraseboek was ook gebruik om ’n klein BKG vir SAG glosse te ontwikkel. Laastens was addisionele nutsfasiliteite, vir die redigering van BKG bome, ontwikkel.

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: see full text for abstract / AFRIKAANSE OPSOMMING: sien volteks vir opsomming

Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In this thesis we describe the creation of an embodied conversational agent which exhibits the behavioural traits of a child who has Asperger Syndrome. The agent is rule-based, rather than arti cially intelligent, for which we give justi cation. We then describe the design and implementation of the agent, and pay particular attention to the interaction between emotion, personality and social context. A 3D demonstration program shows the typical output to conform to Asperger-like answers, with corresponding emotional responses. / AFRIKAANSE OPSOMMING: In hierdie tesis beskryf ons die ontwerp en implementasie van 'n gestaltegespreksagent wat die gedrag van 'n kind met Asperger se sindroom uitbeeld. Ons regverdig die besluit dat die agent reël-gebaseerd is, eerder as 'n ware skynintelligensie implementasie. Volgende beskryf ons die wisselwerking tussen emosies, persoonlikheid en sosiale konteks en hoe dit inskakel by die ontwerp en implementasie van die agent. 'n 3D demonstrasieprogram toon tipiese ooreenstemmende Asperger-agtige antwoorde op vrae, met gepaardgaande emosionele reaksies.

Thesis (MSc (Mathematical Sciences)--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Binary Decision Diagrams (BDDs) are data structures that have been used to solve various problems in different aspects of computer aided design and formal verification. The large memory and time requirements of BDD applications are the major constraints that usually prevent the use of BDDs since there is a limited amount of memory available on a machine. One way of overcoming this resource limitation problem is to utilize the memory available on a network of workstations (NOW). This requires the distribution of the computation and memory requirements involved in the manipulation of BDDs over a NOW. In this thesis, an algorithm for manipulating BDDs on a NOW is presented. The algorithm makes use of the breadth-first technique to manipulate BDDs so that various BDD operations can be started concurrently on the different workstations on the NOW. The design and implementation details of the distributed BDD package are described. The various approaches considered in order to optimize the performance of the algorithm are also discussed. Experimental results demonstrating the performance and capabilities of the distributed package and the benefits of the different optimization approaches are given. / AFRIKAANSE OPSOMMING: Binêre besluitnemingsbome (BBBs) is data strukture wat gebruik word om probleme in verskillende areas van Rekenaarwetenskap, soos by voorbeeld rekenaargesteunde ontwerp en formele verifikasie, op te los. Die tyd- en spasiekoste van BBB-gebaseerde toepassings is die hoofrede waarom BBBs nie altyd gebruik kan word nie; die geheue van ’n enkele is ongelukkig te beperkend. Een manier om hierdie hulpbronprobleem te omseil, is om die gedeelde geheue van die werkstasies in ’n netwerk van werkstasies (Engels: “network of workstations”, oftewel, ’n NOW) te benut. Dit is dus nodig om die berekening en geheuevoorvereistes van die BBB bewerking oor die NOW te versprei. Hierdie tesis bied ’n algoritme aan om BBBs op ’n NOW te hanteer. Die algoritme gebruik die breedte-eerste soektegniek, sodat BBB operasies gelyklopend kan uitvoer. Die details van die ontwerp en implementasie van die verspreide BBB bilbioteek word beskryf. Verskeie benaderings om die gedrag van die biblioteek te optimeer word ook aangespreek. Empiriese resultate wat die werkverrigting en kapasiteit van die biblioteek meet, en wat die uitwerking van die onderskeie optimerings aantoon, word verskaf.

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: We present a system that uses statistical machine learning to identify and extract bibliography information from scientific literature. Techniques for finding and gathering useful information from the ever growing volume of knowledge on the World Wide Web (WWW), are investigated. We use hidden Markov models both for recognition of bibliography styles and extraction of bibliographic information with an accuracy of up to 97%. The accuracy with which we are able to extract this information allows us to present a case study in which we apply methods of citation analysis to information extracted from three areas of machine learning. We use this information to identify core sets of papers that have made significant contributions to the fields of hidden Markov models, neural networks and recurrent neural networks. / AFRIKAANSE OPSOMMING: Ons bied 'n sisteem aan wat gebruik maak van statistiese masjiene wat leer om bibliografiese inligting uit wetenskaplikke literatuur te identifiseer en ontgin. Tegnieke wat aangewend word vir die verkenning en insameling van nuttige inligting vanaf die snel groeiende kennisbron van die WWW, word ondersoek. Ons gebruik verskuilde Markov modelle vir die herkenning van verwysingsstyl en ontginning van verwysingsinligting met 'n akuraatheidspeil van to 97%. Hierdie hoë ontginningsakuraatheid stelons in staat om 'n toepassing van die tegniek op die veld van masjiene wat leer toe te pas. Ons rapporteer hoe ons die tegnieke gebruik het om literatuur wat beduidende bydraes in die velde van verskuilde Markov modelle, neurale netwerke en terugkerende neurale netwerke, te identifiseer.

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: It is possible to improve on the accuracy of a single neural network by using an ensemble of diverse and accurate networks. This thesis explores diversity in ensembles and looks at the underlying theory and mechanisms employed to generate and combine ensemble members. Bagging and boosting are studied in detail and I explain their success in terms of well-known theoretical instruments. An empirical evaluation of their performance is conducted and I compare them to a single classifier and to each other in terms of accuracy and diversity. / AFRIKAANSE OPSOMMING: Dit is moontlik om op die akkuraatheid van 'n enkele neurale netwerk te verbeter deur 'n ensemble van diverse en akkurate netwerke te gebruik. Hierdie tesis ondersoek diversiteit in ensembles, asook die meganismes waardeur lede van 'n ensemble geskep en gekombineer kan word. Die algoritmes "bagging" en "boosting" word in diepte bestudeer en hulle sukses word aan die hand van bekende teoretiese instrumente verduidelik. Die prestasie van hierdie twee algoritmes word eksperimenteel gemeet en hulle akkuraatheid en diversiteit word met 'n enkele netwerk vergelyk.