Thesis (DPhil)--Stellenbosch University, 1977. / ENGLISH ABSTRACT: see item for full text / AFRIKAANSE OPSOMMING: sien item vir volteks.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The design of steel structures needs to incorporate some optimisation procedure that evolves the initial design into a more economic nal design, where this nal design must still satisfy all the initial design criteria. A candidate optimisation technique suggested by this research is the genetic algorithm. The genetic algorithm (GA) is an optimisation technique that was inspired by evolutionary principles, such as the survival of the ttest (also known as natural selection). The GA operates by generating a population of individuals which 'compete' with one another in order to survive, or di erently stated, in order to make it into the next generation. Each individual presents a solution to the problem. Surviving solutions which propagate through to the next generation are typically 'better' or ' tter' than the ones that had died o , hence suggesting a process of optimisation. This process continues until a de ned convergence criteria is met (e.g. speci ed maximum number of generations is reached), where after the best individual in the population serves as the ultimate solution to the problem. This study thoroughly investigates the inner workings that drive the algorithm, after which an algorithm is presented to face the challenges of structural optimisation. This algorithm will be concerned only with sizing optimisation; geometry, topology and shape optimisation is outside the scope of this research. The objective of this optimising problem will be to minimise the weight of the structure, it is assumed that the weight is inversely propotional to the cost of the structure. The motive behind using a genetic algorithm in this study is largely due to its ability to handle discrete search spaces; classical search methods are typically limited to some form of gradient search technique for which the search space must be continuous. The algorithm is also preferred due to its ability to e ciently search through vast search spaces, which is typically the case for a structural optimisation problem. The genetic algorithm's performance will be examined through the use of bench-marking problems. Benchmarking is done for both planar and space trusses; the 10 - and 25 bar truss problems. Such problems are typically analysed with stress and displacement constraints. After the performance of the algorithm is validated, the study commences towards solving real life practical problems. The rst step towards solving such problems would be to investigate the 160 bar truss benchmarking problem. This problem will be slightly adapted by applying South African design standards to the design, SANS (2005). This approach is more realistic, when compared to simply specifying stress and displacement constraints due to the fact that an element cannot simply be assigned the same stress constraint for tension and compression; slenderness and buckling e ects need to be taken into account. For this case, the search space will no longer simply be some sample search space, but will consist of real sections taken from the Southern African Steel Construction Handbook, SAISC (2008). Finally, the research will investigate what is needed to optimise a proper real life structure, the Eskom Self-Supporting Suspension 518H Tower. It will address a wide variety of topics, such as modelling the structure as realistically as possible, to investigating key aspects that might make the problem di erent from standard benchmarking problems and what kind of steps can be taken to over-come possible issues and errors. The algorithm runs in parallel with a nite element method program, provided by Dr G.C. van Rooyen, which analyses the solutions obtained from the algorithm and ensures structural feasibility. / AFRIKAANSE OPSOMMING: Die ontwerp van staal strukture moet 'n sekere optimalisasie proses in sluit wat die aanvanklike ontwerp ontwikkel na 'n meer ekonomiese nale ontwerp, terwyl die nuwe ontwerp nog steeds aan al die aanvanklike ontwerp kriteria voldoen. 'n Kandidaat optimeringstegniek wat voorgestel word deur hierdie navorsing is die genetiese algoritme. Die genetiese algoritme (GA) is 'n optimaliserings tegniek wat ge- ïnspireer was deur evolusionêre beginsels soos die oorlewing van die sterkste (ook bekend as natuurlike seleksie). Dit werk deur die skep van 'n bevolking van individue wat 'kompeteer' met mekaar om dit te maak na die volgende generasie. Elke individu bied 'n oplossing vir die probleem. Oorlewende oplossings wat voortplant deur middel van die volgende generasie is tipies 'beter' of ' kser' as die individue wat uitgesterf het, dus word 'n proses van optimalisering word saamgestel. Hierdie proses gaan voort totdat 'n bepaalde konvergensie kriteria voldoen is (bv. 'n gespesi seerde aantal generasies), waar na die beste individu in die bevolking dien as die uiteindelike oplossing vir die probleem. Hierdie studie ondersoek die genetiese algoritme, waarna 'n algoritme aangebied word om die uitdagings van strukturele optimalisering aan te spreek. Hierdie algoritme het alleenlik te doen met snit optimalisering; meetkunde, topologie en vorm optimalisering is buite die bestek van hierdie navorsing. Die motief agter die gebruik van 'n genetiese algoritme in hierdie studie is grootliks te danke aan sy vermoë om diskrete soek ruimtes te hanteer; klassieke soek metodes word gewoonlik beperk tot 'n vorm van 'n helling tegniek waarvoor die soektog ruimte deurlopende moet wees. Die algoritme is ook gekies as gevolg van sy vermoë om doeltre end deur groot soektog ruimtes te soek, wat gewoonlik die geval vir 'n strukturele probleem met optimering is. Die genetiese algoritme se prestasie sal ondersoek word deur die gebruik van standaarde toetse. Standarde toetse word gedoen vir beide vlak en ruimte kappe, die 10 - en 25 element vakwerk. Sulke probleme word tipies met spanning en verplasing beperkings ontleed. Na a oop van die bekragtiging van die algoritme, word praktiese probleme hanteer. Die eerste stap in die rigting sou wees om die 160 element vakwerk toets probleem te ondersoek. Hierdie probleem sal e ens aangepas word deur die toepassing van die Suid-Afrikaanse ontwerp standaarde, SANS (2005) aan die ontwerp. Dit is 'n meer realistiese benadering in vergelyking met net gespesi seerde spanning en verplasing beperkings as gevolg van die feit dat 'n element nie net eenvoudig dieselfde spanning beperking vir spanning en druk toegeken kan word nie; slankheid en knik e ekte moet ook in ag geneem word. In hierdie geval sal die soek ruimte nie meer net meer eenvoudig 'n sekere teoretiese soek ruimte wees nie, maar sal bestaan uit ware snitte wat uit die Suid Afrikaanse Konstruksie Handboek kom, SAISC (2008). Ten slotte sal die navorsing ondersoek instel na 'n standaard Eskom Transmissie toring en dit sal 'n wye verskeidenheid van onderwerpe aanspreek, soos om die modellering van die struktuur so realisties as moontlik te maak, tot die ondersoek van sleutelaspekte wat die probleem verskillend van standaard toets probleme maak en ook watter soort stappe geneem kan word om moontlike probleme te oor-kom. Die algoritme werk in parallel met 'n eindige element metode program, wat deur Dr GC van Rooyen verskaf is, wat die oplossings ontleed van die algoritme en verseker dat die struktuur lewensvatbaar is.

published_or_final_version / Education / Doctoral / Doctor of Philosophy

This study dealt with the problem of investigating the validity of two recently developed paper-and-penci1 tests of programmer aptitude , the Aptitude Test for Programmer Personnel (ATPP) and the Computer Programmer Aptitude Battery (CPAB), in predicting success in computer programming.

The purpose of this study is to identify what detail design tools are more productive for the different types of professional software developers. By establishing a match between the detail design tool and the cognitive style of the professional programmer, the end product (Information Systems) should be of a higher quality. Two laboratory experiments were conducted. The first experiment was with professional Software Developers; the second one was with students. The dependant variables considered in this study were the number of semantic errors and the time required to complete a design task for conditional logic. The independent variables were the cognitive style of the subject, the complexity of the task, and the detail design tools. Decision trees, flowcharts and pseudocode were used as detailed design tools. Field dependence was the only dimension of cognitive style that was tested.

This paper discusses FORTRAN optimizations that the user can perform manually at the source code level to improve object code performance. It makes use of descriptive examples within the text of the paper for explanatory purposes. The paper defines key areas in writing a FORTRAN program and recommends ways to improve efficiency in these areas.

As network processors have advanced in speed and efficiency they have become more and more complex in both hardware and software configurations. Intel's IXP1200 is one of these new network processors that has been given to different universities worldwide to conduct research on. The goal of this thesis is to take the first step in starting that research by providing a stable system that can provide a reliable platform for further research. This thesis introduces the fundamental hardware of Intel's IXP1200 and what it takes to install both hardware and software using both Windows 2000 and Linux 7.2 as the operating system in support for the IXP1200. This thesis will provide information on the installation of hardware and software configuration for the IXP1200 including Intel's Software Development Kit (SDK). Upon completion this platform can then be used to conduct further research in the development of the IXP1200 network processor. It provides a hardware and software installation checklist and documentations of problems encountered and recommendations for their resolution. Along with providing an example of using preexisting code that has been modified to filter packets of TCP or UDP to different ports.

Sedan hösten 2018 är programmering en del av det matematiska innehållet algebra i läroplanen. Eftersom många lärare känner en osäkerhet angående matematikundervisning om programmering, finns ett behov av att veta mer om hur sådan undervisning kan se ut. Genom designforskning skapas i den här studien förståelse av hur undervisning om programmering i matematik kan designas för att utveckla elevers rumsuppfattning och förståelse av hur entydiga stegvisa instruktioner kan skapas och förbättras. Designforskning bygger på att utarbeta interventioner (lektioner) samt testa och revidera dem på ett systematiskt sätt. Viktiga byggstenar för att kunna lära sig programmera är rumsuppfattning och förståelse av instruktioner. Den här studien fokuserar på utarbetningen av designprinciper som leder till en utveckling av byggstenarna och konstruktionen av givande undervisningsaktiviteter. Undervisningsaktiviteterna sker på ett urkopplat sätt, det vill säga utan användning av digitala verktyg. Studiens viktigaste resultat är betydelsen av fyra designprinciper; att variera objektets startposition, att blanda instruktioner, att testa själv och att uppleva 2D/3D-perspektivet samt två undervisningsaktiviteter och ett arbetsblad som verkar leda till en utveckling av rumsuppfattning och en förståelse av instruktioner. / Since autumn 2018, programming is a part of the algebra content in the Swedish curriculum. Due to an insecurity many teachers feel towards mathematic teaching about programming, there is a need to know what such teaching can look like. This design research study creates an understanding of how mathematical programming lessons can be designed to develop students spatial reasoning and understanding of how distinct step-by- step instructions can be created and improved. Design research builds on developing interventions (lessons), and testing and adjusting them in a systematic way. Important aspects for being able to learn how to program are spatial reasoning and an understanding of instructions. This design research focuses on the development of design principles that will lead to an understanding of the important aspects of learning how to program and the construction of rewarding teaching activities. The activities are unplugged, meaning that there are no digital tools involved. The most important finding of this study is the importance of four design principles; variation of the objects starting point; mixing of instructions; testing and 2D/3D as well as two teaching activities and a worksheet that seem to lead to a development of spatial reasoning and an understanding of instructions.

O objetivo deste trabalho foi desenvolver um programa para auxílio didático em disciplinas que envolvam a análise estrutural, o dimensionamento e o detalhamento de pórticos planos de concreto armado. O programa age como um pós-processador, obtendo dados, como esforços nos nós e deslocamentos nodais de um processador existente, interpreta esses dados e dimensiona a estrutura para resistir aos esforços de acordo com a NBR 6118:2001. Para verificação dos resultados foi feita uma comparação entre o dimensionamento efetuado pelo programa DTool e o realizado pelo programa TQS, justificando as diferenças que possa haver entre os dois processos. / The purpose of this paper is the development of a program capable to aid didactically in disciplines related to structural analysis, and in designing and projecting reinforced concrete plane frames. This software works as a post-processor, receiving data from a processor such as nodal efforts and displacements. It interprets those data and designs the structure in order they resist acceptably those stresses, using processes that are recommended by the brazilian code NBR 6118:2001. For results verification a comparison between design by DTool and TQS is presented, and eventual differences between them are justified.

As new introductory block-based coding applications for young students to learn basic computer science concepts, such as, loops and conditionals, continue to increase in popularity, it is necessary to consider the best method of teaching students these skills. Many of these products continue to exhibit programmatic misconceptions of these concepts and many students struggle with how to apply what they learn to a text-based format due to the difficulties with learning the syntactic structure not present in block-based programming languages. If the goal of teaching young students how to program is meant to develop a set of skills they may apply when learning more complex programming languages, then discerning how they are introduced to those practices is imperative. However, few studies have examined how the specific modality in which students are taught to program effects how they learn and what skills they develop. More specifically, research has yet to effectively investigate modality in the context of an educational coding game where the modality feature is controlled, and content is consistent throughout game-play. This is mainly due to the lack of available games with this feature designed into the application. This dissertation explores whether programming modality effects how well students can learn and transfer computer science concepts and practices from an educational programming game. I proposed that by being guided from a blocks-based to text-based programming language would instill a deeper understanding of basic computer science concepts and would support learning and improve transfer and performance on new challenging tasks. Two experimental studies facilitated game-play sessions on the developed application for this project. The first study was a 2x2 between subjects design comparing educational module (game versus basic) and programming modality (guided versus free choice). The findings from Study 1 informed the final version design for the module used in the second study where only the game module was used in order to focus the comparison between programming modality. Findings showed that students who coded using the game module performed better on a learning test. Study 2 results showed that students who are transitioned from blocks-based to text-based programming language learn basic computer science concepts with greater success than those with the free choice modality. A comparative study was conducted using quantitative data from learning measures and qualitative video data from the interviews during the challenge task of the second study. This study examined how students at the extreme levels of performance utilized the toggle switch feature during game-play and how the absence of the feature impacted how they completed the challenge task. This analysis showed two different methods of toggle switch usage being implemented by a high and low performing student. The high performing student utilized the resources more often during the challenge tasks in lieu of leveraging the toggle switch and were still able to submit high level code. Results suggest that a free choice student who uses the feature as a tool to check their prewritten code rather than a as short cut for piecing code together as blocks and submitting the text upon the final attempt. This practice leads to a shallower understanding of the basic concepts and make it extremely difficult to expand and apply that knowledge to a more difficult task. This dissertation includes five chapters: an introduction and theoretical framework, a game design framework and implementation description, two experimental investigations, and a quantitative and qualitative comparative analysis. Chapter one provides the conceptual and theoretical framework for the two experimental investigations. Chapter two describes the theory and design structure for the game developed for this dissertation work. Chapter three and four will discuss the effects of programming modality on learning outcomes. Specifically, chapter 3 focuses on implications of programming modality when determining how to implement changes for the design of the game for Study 2. Chapter five discusses a comparative analysis that investigated differing work flow patterns within the free choice condition between high and low performing students. Results from these three chapters illustrate the importance of examining this component of the computer science education process in supplemental games for middle and high school students. Additionally, this work contributes in furthering the investigation of these educational games and discusses implications for design of similar applications.