Theses and Dissertations

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Computer literacy as additional empowerment mechanism in learning programmes
(2004-01) Van Staden, A; Hoffmann, E. C.
The world of digital interactivity, of computers, of cyberspace and the "e-revolution', is making computer literacy more indispensable than ever. There is an increasing demand for ICT skills worldwide- South Africa is not alone in identifying shortages. The information and communication technology in South Africa is exacerbated by emigration on the one hand and the previously disadvantaged learners on the other hand. With an education system that is stretched, higher education has not kept pace with information and communication technology training in South Africa, therefore learners display a shortcoming of basic computer skills. The purpose of this study is to emphasise the importance of implementing computer literacy training throughout the entire learning programme of learners at higher education institutions. Learners randomly selected from the Faculty of Management Sciences, Vaal University of Technology, indicated their computer literacy via questionnaires and levels of experience. It is clear that the abilities of the learners are not sufficient to ensure that they are computer literate or that they will be effective users in the workplace. This study results in a powerful argument in support of the extension of continued growth in computer usage in the workplace.
Secretary versus office manager : a paradigm shift
(2004-02) Wilkinson, Judith Levine; Garnett, A; Buys, C.
The objectives of this research project were primarily to determine the requirements of commerce and industry for competent office managers, to contribute to the curriculum development of information administration, to facilitate action learning (AL) in information administration, and by making changes in training to empower learners to become competent office managers. The influence of training and development of office managers is explained. The National Qualification Framework (NQF) integrates training and education in business and management on all levels. An important aspect is, that professional institutes, education and training institutions and other stakeholders, are combining experience to collectively benefit learners, employers, professions and the economy as a whole. A combination design of both quantitative (traditional) research and qualitative (action) research, including two questionnaires (open-ended and closed), interviews, observations, focus groups and a case study, were used. This study proved the relevance of office management education, by way of the demand for a formal qualification by commerce and industry, as a primary result of the phenomenal change in technology and the need for multi-skilled office managers. A contribution to the training of office managers concerning the following aspects was made: A profile for an office manager, as well as highlighting the need for training, curriculum development, and portfolio development
Design and development of a high frequency Mosfet driver
(2004-11) Swart, Arthur James; Pienaar, H. C. van Z
A high-power Mosfet was incorporated as a switching device into the efficient Class E configuration, where the switching device switches current through itself either completely on or completely off at high frequencies. The first objective of this project was to demonstrate the effectiveness of a phase-lock loop circuit in generating stable high frequencies when connected in an indirect frequency synthesizer configuration. The indirect frequency synthesizer has established itself as a versatile frequency generator capable of generating high frequencies based on a lower stable reference frequency. The frequency generation stage incorporates a phaselock loop circuit, a frequency divider and a stable reference frequency section. The phase-lock loop section incorporates the TTL based 74HC 4046 that is based upon the common CMOS 4046 integrated circuit. The frequency divider section is built around the CMOS-based 4526 whilst the reference frequency section incorporates the CMOS-based 4060. The frequency synthesizer produced a range of frequencies from 50 kHz to 8 MHz in 50 kHz steps. The output voltage was constant at 5,5 V. The second objective was to show that the complementary emitter follower is indeed a worthy Mosfet gate drive circuit at high frequencies. The Mosfet driver stage produced a voltage signal of at least 11 V, being able to source and sink relatively high peaks of current, especially at high frequencies. Voltage amplification occurred through the use of multiple CMOS-based 40106 inverters. The complementary emitter follower, known for its low output impedance and its ability to source and sink large amounts of current, was an important component in the final Mosfet gate section.
Internal customer service in Sasol Technology: accountability and productivity of administative support in the research and development environment
(2006-01) Mohomane, Pelonomi Banana Patricia Lillian; Dhurup, M; McFarlane, M
The buzzwords in South African business today is quality service and customer satisfaction. Service quality is an important determinant of customer satisfaction. It is therefore important to measure customer satisfaction and to solicit internal customers perceptions on service received. This research was primarily undertaken to evaluate the quality of services rendered by administrators to Sasol Technology R&D employees. The research is supported by a detailed study of quality and customer service. An adapted internal service quality scale (INSERVQUAL) was used to measure service quality. A thirty item scale was developed, for the empirical study. The instrument was then subjected to a scale purification process through exploratory factor analysis. Both the expectation and perception elements were used in measuring service quality. The five dimensions of service quality namely Accessibility and Tangibility, Assurance, Empathy, Reliability and Responsiveness were identified as internal service quality dimensions. Aspects of Accessibility and Tangibility were incorporated as a single dimension in this study. A six- point Likert scale was used in the questionnaire. The low end of the scale represented a negative response, whilst the high end represented a posit,ive response. With a response rate of 63% from internal customers, the researcher was able to provide evidence that service quality dimensions may influence an employee's perception of the administrators' service quality. The finding in this study also suggests the need for further research to examine customers' expectations in other related services as well as in different culture contexts. The testing of the modified internal customer model of internal marketing developed and described in this study indicates that Access, Assurance, Empathy, Reliability and Responsiveness dimensions may be a useful approach to enhancing service quality.
Design and development of a high efficiency modulated Class E amplifier
(2006-01) Crafford, Crafford, Hendrik Lambert Helberg Hendrik Lambert Helberg; Pienaar, H. C. v Z.
Amplitude modulation is not commonly associated with effective amplifying. This work focuses on implementing amplitude modulation into a high efficiency Class E amplifier. Different types of amplifiers are compared with each other, to show the advantages of using a Class E amplifier. The theory of the Class E amplifier is dealt with in detail. A harmonic filter is designed for the amplifier to make it radio spectrum friendly. The modulation process is implemented with the aid of a transformer into the Class E amplifier. The advantage of this is that the transformer serves both as a radio frequency choke for the Class E circuit as well as a modulator. The implementation of the amplitude modulation into the high efficient Class E circuit was successful. The final Class E circuit had superb efficiency, the harmonic filter showed good harmonic attenuation and the modulation process had low distortion. All this resulted in a fine low power AM transmitter.
Design and development of a 100 W Proton exchange membrane fuel cell uninterruptible power supply
(2006-01) Du Toit, Johannes Paulus; Pienaar, H. C. v Z.
This study presents the design of a proton exchange membrane fuel cell stack that can be used to replace conventional sources of electrical energy in an uninterruptible power supply system, specifically for use in the telecommunications industry. One of the major concerns regarding the widespread commercialization of fuel cells is the high cost associated with fuel cell components and their manufacturing. A fuel cell design is presented in which existing, low-cost, technologies are used in the manufacture of cell components. For example, printed circuit boards are used in the manufacturing of bipolar flow plates to significantly reduce the cost of fuel cells. The first objective was to design, construct and test a single fuel cell and small fuel cell stack in order to evaluate the use of printed circuit boards in bipolar plate manufacturing. Since the use of copper in a fuel cell environment was found to reduce the lifetime of the cells, the bipolar plates were coated with a protective layer of nickel and chrome. These coatings proved to increase the lifetime of the cells significantly. Power outputs of more than 4 W per cell were achieved. The second objective was to analyze a small fuel cell stack in order to obtain a model for predicting the performance of larger stacks. A mathematical model was developed which was then used to design an electronic circuit equivalent of a fuel cell stack. Both models were adapted to predict the performance of a fuel cell stack containing any number of cells. The models were proven to be able to accurately predict the performance of a fuel cell stack by comparing simulated results with practical performance data. Finally, the circuit equivalent of a fuel cell stack was used to evaluate the capability of a switch mode boost converter to maintain a constant voltage when driven by a fuel cell stack, even under varying load conditions. Simulation results showed the ability of the boost converter to maintain a constant output voltage. The use of supercapacitors as a replacement for batteries as a secondary energy source was also evaluated.
A food multi-mix to address malnutrition amongst primary school children living in Eatonside
(2006-01) Oosthuizen, Delia; Napier, C.; Oldewage-Theron, Wilna
The primary objective of this study was to formulate a multi-mix, which could supply at least one-third of the daily requirements of primary school children, aged six to 13 years. The secondary objective was to ensure the adherence to the criteria of multi-mix formulation, which included affordability, convenient, palatability, culturally acceptable and cost effective, whilst providing high nutritional value for the specified target group. The nutritional criteria included the Index Nutrient Quality (INQ) and Energy Density (ED) requirements, for a specific target group. This study was conducted in Eatonside, an informal settlement situated in Gauteng. A situational analysis previously conducted in Eatonside (Napier 2003) showed that the children between the ages of six and 13 years, were 17% underweight (weight-for-age -2SD from the reference NCHS median), 12,7% were wasted (BMI-for-age -2SD) and 18% stunted (height-for-age -2SD). With the nutritional requirements of children and the most consumed food list, the multi-mix formulation began. Foods from the Top 20 list (Napier 2003), were combined with the ingredients most common within the households, and vegetable gardens already established . Estimated nutritional values were calculated using the food composition tables of South Africa. The ingredients were prepared and chemically analysed to determine the experimental nutritional value and to assess if the nutritional objectives were being achieved. The multi-mix was then combined with other commonly consumed ingredients to form recipes and sensory evaluated by professionals and the primary school children to assess the acceptability of the multi-mix and recipes. The multi-mix and recipe products were then sent for shelf life testing to assess its storage time at room temperature. The results from the nutritional analyses showed nutrient values to be above 30 percent of the Estimated Average Requirements (EAR). The INQ of the targeted nutrients was above 1,0 and the ED at 3,7kcal/g, which was within the 3,6-4,5 kcal/g requirements. The sensory evaluation for the multi-mix recipes had proved favourable response to snack items with preference for sweet products. The final evaluation session resulted in scores of 83.9 percent preference to the biscuit with the sweet muffin scoring 94.5 percent liking, whilst the savoury muffin at 73.1 percent. The average scores for all three recipes were above 80 percent. The multi-mix had a shelf life of minimum one-month, the biscuit, seven days and muffins, only 24 hours, at room temperature. The objectives of cultural acceptability had been achieved through the positive response from the use of ingredients within the community. The multi-mix had been cost effective as the final cost of R1.55, was within the R2.90 spent per person per day, for all three meals (Oidewage-Theron eta/. 2005). Further studies need to be conducted in order to implement the multi-mix into an intervention within the community to assess the effect on nutritional status. This study, aimed to reduce the underlying cause of malnutrition, food insecurity, by improving the nutritional status of children aged six to 13 years with the strengthening of food intake, through the combination of various scant ingredients, a multi-mix, providing maximum nutritional value with small quantities. An advantage of the multi-mix is a lower cost when compared with tablet supplementation on the market and versatility in relation to various recipes.
Design and development of a high performance zinc air fuel cell
(2006-06) Lourens, Dewald; Pienaar, H. C. v Z.
The demand for efficient and environmentally friendly power sources has become a major topic around the world. This research explores the capability of the zinc-air fuel cell to replace conventional power sources for various applications, more specifically telecommunication systems. The research consisted of a theoretical study of the zinc-air fuel cell and its components, as well as their performance characteristics. A zinc-air fuel ce.ll and test rig were built, and the system was tested under various conditions. It was found that the zinc-air fuel cell has an advantage over other fuel cells in that it does not require any expensive materials or noble metals, reducing the overall cost of such a system. The fuel cell showed the potential to power various applications, but problems persisted in the fueling process as well as constant leaking of the aqueous electrolyte.
Design and development of a remote monitoring system for fuel cells
(2006-07) Komweru, Laetitia; Pienaar, H. C. v Z.
This dissertation presents the design and development of a remote monitoring system (RMS) for polymer electrolyte membrane fuel cells (PEMFC) to facilitate their efficient operation. The RMS consists of a data acquisition system built around the PIC 16F874 microcontroller that communicates with a personal computer (PC) by use of the RS232 serial communication standard, using a simple wired connection between the two. The design also consists of a human machine interface (HMI) developed in Visual Basic 6.0 to provide a platform for display of the monitored parameters in real time. The first objective was to establish performance variables and past studies on PEM fuel cells revealed that variables that affect the system's performance include: fuel and oxidant input pressure and mass flow rates as well as operation temperature and stack hydration. The next objective was to design and develop a data acquisition system (DAS) that could accurately measure the performance variables and convey the data to a PC. This consisted of sensors whose outputs were input into two microcontrollers that were programmed to process the data received and transfer it to the PC. A HMI was developed that provided graphical display of the data as well as options for storage and reviewing the data. The developed system was then tested on a 150Watt PEM fuel cell stack and the data acquisition system was found to reliably capture the fuel cell variables. The HMI provided a real-time display of the data, with alarms indicating when set minimums were exceeded and all data acquired was saved as a Microsoft Excel file. Some recommendations for improved system performance are suggested.
Purchasing patterns of major plant staples in low-income households in the Vaal Triangle
(2006-09) Amuli, Dorah John; Duvenage, S. S.; Spowart, J.
Very poor families, mostly in developing parts of the world, consume a monotonous staple diet out of need and are least likely to eat healthy diets. This study focussed on how the low income households in the urbanised informal settlement of Eatonside used available income to buy plant staples (situation analysis), the share of the food budget Rand allocated to this (investigative survey), as well as the extent of influence of low income, food prices, and locality on the buying behaviour. The aspects of where, how much, when and how low-income households purchased were examined in order to determine the purchasing patterns for plant staples. From the households surveyed, most (62,2%) received an income of less than R500.00/month. Household size affected food purchasing and varied according to the type of household head. Total food budget expenditure by male-headed households was 83,1 percent, 58,1 percent by female-headed households and 27,9 percent by de facto headed households. The total average share/portion of the food budget allocated to purchasing of plant staples was reported as R64.63 ±(R8.04). While male-headed households spent 15 percent of the total share/portion/month allocated to purchasing of plant staples, female-headed households spent 23,1 percent and de facto-headed households spent 21,1 percent. Total average expenditure allocated to plant staples was 58,1 percent for maize meal, 23,2 percent for rice, 4,6 percent for mabella, 3,9 percent for sugar beans, 3,7 percent for samp, 2,5 percent for split peas and 4 percent on various other plant staples. Price and quantity (63,6%) were main purchasing indicators. Less plant staples were purchased when prices were high and more when prices were low. Normally when prices of other food products are high, people buy more staples to survive. Most frequent purchases for maize meal was 12,5 kg (65%) once a month (41,7%) at an average price of R32.80 per unit from spaza shops. Plant staples were mostly purchased once a month (80,2%) at supermarkets (47%) or spaza shops (42%). The urbanised low income households of Eatonside were poor, leading to the allocation of a major component of the budget to food (plant staples). Purchasing patterns, plant staples, low-income households, Eatonside informal settlement.
Visual learning in a graphic design setting
(2006-10) Chmela-Jones, Katarzyna Anna; Gaede, R. J.; Buys, C.
An exploratory study was undertaken at three campuses of the Vaal University of Technology in response to weak examination results in one of the subjects of the graphic design curriculum. The aim of the study was to investigate visual learning strategies as used in conjunction with co-operative learning approaches in a higher education setting and to asses the appropriateness of these learning approaches in the discipline of graphic design at first-year level. The research questions that guided the study focused on how first-year graphic design learners experience (a) visual learning strategies, (b) a cooperative learning environment, as well as (c) the combination of these. The literature review component of the study covered (1) the fundamentals of visual learning, including the concepts of visual literacy, visual semiotics and visual culture; (2) graphic design education, especially in a South African context; and (3) principles of co~operative learning, including Avenant's requirements for successful group work. In the field work component of the study, multiple-choice questionnaires, open-ended questionnaires and focus group interviews were used as the main data collection methods. The results of the study did not indicate that first-year learners enrolled in the discipline of graphic design are likely to benefit from a combination of visual learning and co-operative learning strategies. Therefore, the implementation of a combination of the above-mentioned teaching strategies is not recommended in this setting.
Photo-elicitation in qualitative research
(2006-11) Pompe van Meerdervoort, Tracy; Gaede, R. J.
The aim of the study The aim of the study is to find an optimal research methodology that is both beneficial to qualitative researchers (regarding data quality and interviewee participation) and research participants (regarding enjoyment of the research process and means of expression). This takes the form of a comparison assessing the use of the visual method of photo-elicitation in qualitative interviews. Firstly, photo-elicitation interviews and standard qualitative interviews as two different methodologies are compared. In this study the research subjects are children, and as noted in Chapter 3, photo-elicitation is particularly applicable to young research subjects, as it tends to break down the communication barriers
Combating the corporate paper war: optimising electronic mail and electronic filing
(2006-11) Bothma, Marchelle Marelize; Hoffmann, E. C.
The primary objective of this research project was primarily to investigate filing methods and mailing practices in the computer support or administrative environment with specific focus on the abuse of paper. The research design consisted of an exploratory investigation in selected Higher Education Institutions in the Province of Gauteng whereby a structured questionnaire was used as a measuring instrument. The investigation was sub-divided into two categories, namely, paper-based filing systems and mailing systems as opposed to electronic filing and mailing systems. In the empirical findings, analysis and interpretations, correlation and cross-tabulation were done on all sets of variables in order to determine whether any meaningful associations could be found. With reference to the title of this study "Combating the corporate paper war: optimising electronic mail and electronic filing", it has been proven that the war against paper abuse is far from over. Perceptions regarding a future paperless office and assumptions that technology such as the electronic mail facility and electronic filing could assist organisations to combat paper abuse were unfounded, due to a lack of guidance and control measures in the corporate environment. Consequently, it is recommended that an e-filing and e-mailing model be created and followed in conjunction with specified computer software features in order to counteract the abuse of paper. Follow-up research could focus on electronic filing methods versus scanning of documents for filing purposes.
Development of a computer program for general use in the design of solar powered water pumping systems
(2007-05) Denny, Ernest Edward; Case, M. J.; Joubert, M. J.
Water is one of the basic necessities of life. In addition to being essential for the maintenance of life, this basic resource is a crucial requirement for combating poverty, hunger and disease in South African communities. In excess of twenty-nine percent of South African households do not have water in either their dwellings, or on site (source: 2005 RSA census data). This study documents an engineering solution to the problem of water pumping, utilising renewable energy (solar power) and readily available pumping hardware, configured via a structured design process. Resultant from the research, a software application has been developed that facilitates the design of solar (photovoltaic) powered water pumping applications. The selected design configuration of a nontracking, stand-alone, directly coupled system provides for the most robust and least complex design possible, making it imminently suitable for application in rural African conditions. Operation of the program is via a simple graphical user interface, with full and context sensitive help provided. It is tailored for use in Southern Africa and is provided with comprehensive databases of location dependant design information such as solar radiation, meteorology and magnetic declination data, together with expandable databases of pre-configured pump and solar panel hardware specification data. The program is manufacturer and component independent, with no affiliations in the choice of hardware. Design methodologies, together with a component matching strategy. Optimisation is achieved by a quantitative and efficiency 'best fit' analysis of the selected hardware components within the design context. Design output predictions are tabulated and graphed by month for a period of one year, allowing design visualisation. The application has been named 'South African Stand-alone Solar (PV) Water Pumping Design Aid', abbreviated as 'SAS-SWP' in its run-time form. The SASSWP application is illustrated in the functional overview provided in Figure 1.
The relationship between visual and verbal codes of visual rhetoric in a sequential art setting
(2007-11) Van der Merwe, Ernest; Gaede, R. J.
The aim of the study was to examine the relationship between visual and verbal codes of visual rhetoric in a sequential art setting. The literature investigation component of the study covered: (1) the notion of visual literacy; (2) the principles of visual rhetoric, and (3) trends in sequential art. The empirical component of the study involved the production of sequential art test material with an accompanying questionnaire in order to measure the comprehension of visual rhetoric in a sample of 197 undergraduate students at the Vaal University of Technology. The working hypotheses that guided the study were, firstly, that the comprehension of the visual code of the visual rhetoric used in a sequential art setting differs between (a) study participants that received visual training prior to the data collection and (b) study participants that received no visual training prior to the data collection, and secondly, that the comprehension of the visual code of the visual rhetoric used in a sequential art setting differs between (a) study participants that received test material in their home language and (b) study participants that did not receive the test material in their home language. Following a one-way ANOVA analysis of the questionnaire data, the first hypothesis indicated a significant statistical difference (p=O.OO) and was not rejected. The second hypothesis indicated no significant statistical difference (p=0.138) and was rejected. Based on the result obtained, possibilities for further research were motivated.
Evaluative criteria applied by selected female fashion consumers in the Vaal Region when purchasing casual daywear
(2007-12) Hugo, Susanna Hendrina; Egal, A. A.
Criteria used by fashion consumers to assess the quality of apparel products during the decision-making process are a good indication of what considerations to keep in mind for customer satisfaction. Evaluative criteria of concern to apparel customers are intrinsic attributes, involving physical features such as design/style, materials and construction and performance features such as aesthetic and functional aspects and extrinsic attributes such as price, brand, store image, label, country of origin and appropriateness for the occasion, in this case casual day wear. The broad research aim of this exploratory study was to determine which evaluative criteria were used by female fashion consumers in the Vaal Region to determine apparel quality when purchasing casual daywear, and to what extent the various criteria were applied. A self-administered, structured questionnaire was used to collect the data. Sections 1 and 2 measured the importance of intrinsic and extrinsic clothing evaluative criteria. Section 3 investigated the frequency with which the respondents bought casual daywear at various store types, namely specialty, department and discount stores, while section 4 gathered the demographic information of the respondents. A representative sample was chosen from the academic personnel of all seven tertiary institutions in the Vaal Region. The majority of the lecturers (38.00 percent) were between the ages of 31 and 40, which can be described as relatively young, constituting a group sometimes referred to as baby busters or Generation X. Although the predominant population group was white (65.71 percent), a quarter of the respondents were black. They all had a tertiary qualification, indicating a relatively high educational level, and an average income. These espondents were predominantly married, either by orthodox or customary marriage. Regarding the application of evaluative criteria for quality assessment, these respondents used intrinsic apparel attributes to a greater extent than extrinsic attributes. Three functional performance aspects namely durability, comfort and fit were rated equal and most important for judging quality, followed closely by an extrinsic attribute namely appropriateness for casual daywear. Three clusters of respondents could be distinguished, each with a specific disposition towards the evaluative criteria. The most popular store type for clothing was Department stores, followed by Discount and Specialty stores.
A model to reduce the divide between South African secondary institutional skills and knowledge, and the entrance requirements for an information technology diploma course
(2008) Baxter, Roger; Lombard, A.; Jordaan, A.
Historically, access to information technology (IT) in South Africa educational institutions has been socially stratified. As a result, many new learners seeking to enter South African tertiary institutions fail to meet the requirements of their preferred course and institution. In 2003, the Department of Information and Corrununications Technology at the Vaal University of Technology (VUT), in conjunction with the National Institute for Information Technology (NIIT), an internationally recognised IT organisation, introduced a short course named the Information Technology Boot Camp (ITBC). This course is now known as the Introduction to Information Technology course (Intro-to-IT). The course is targeted at learners who want to study the IT diploma at the VUT but, who as a result of their Matriculation marks, do not meet the VUT's entrance requirements. The aim of the course is to prepare and qualify these learners for possible acceptance into the IT diploma at the VUT. Although the Intro-to-IT course has impacted positively on the VUT, research has found that learners progressing from the Intro-to-IT course into the IT diploma course experience difficulties in solving programming problems in a logical way. Therefore, the failure rate in Development Software I, a first-semester programming subject, is relatively high. The model described in this study encompasses alterations (implemented and still to be implemented) to the syllabus and content of the Intro-to-IT course, changes to the learning methods and time frames for subjects, and the measurement of these changes in comparison to previous results. The model also includes a software program, which will assess the Intro-to-IT applicants, store results and provide analytical data on all learners' marks and results for the Intro-to-IT short course at the VUT. This model is designed to provide the necessary skills, knowledge and basic logic required to allow successful Intro-to-IT learners the opportunity of success when they enter the VUT's IT diploma stream.
Managerial and socio-economic implications of the implementation of telework in Gauteng
(2008) Van Wyk, Elsa; Hoffman, E. C.
Telework can be defined as a flexible work arrangement, where selected employees work at home one or more days per week or at a site near home, instead of physically travelling to a central workplace. Telework has progressed globally, especially during the past decade to a work option that has an impact on commerce and industry in a most beneficial manner. This flexible work arrangement emerged in organisations because of the development of information and communication technology (ICT) that forms the key component of the teleworkers equipage. This investigation focussed on telework aspects, such as the effects on the environment, quality of life and economic effects. It is evident that telework generates significant benefits to the corporate environments, improves work and personal life experiences for human resources, improves environmental and social circumstances and has resulted in a significant paradigm shift in the corporate arena. The investigation also identified barriers that constrain managers from implementing telework. The investigation furthermore determined how South Africa, in particular, might benefit socioeconomically Inferential conclusions indicate that telework could counteract many of South Africa's transport and related socio-economic problems that pose detrimental consequences for the environment and other resources, as is the case in many other countries.
Dynamic modelling of a bolted disc rotor assembly
(2008) Blignaut, Gert; Roberts, Johan
A project investigating the behaviour of an assembled preloaded rotor was performed for an M-Tech qualification in the Mechanical Engineering Department. Pre-Stressing of mechanical structures is widely applied to improve their performance, and in this project the behaviour of an assembled preloaded rotor was investigated. An Impact Test was done on the structure to see if induced stresses originated by a set of bolts which keep the discs system together, would influence the natural dynamic response or the rotor. Tendencies in the natural response were investigated. Analytical models like the Finite Element Beam model and the Solid Finite Element model were studied in order to find a represntative description of this particular structure's dynamic behaviour after pre-tension. From the experimental results it was apparent that the slenderness of the pre-tensioned sector influences the natural frequency. The solid finite element model appears to be the most applicable model to present the assembled rotor-disk system as a continuous shaft. Furthermore, modelling and predictions for a typical rotor and similar assembled structures can be generated from the findings.
Plant systems integration using the SAMI model to achieve asset effectiveness in modern plants
(2008-05) Joubert, André; Jordaan, A.; Case, M. J.
In recent years, industrial plant maintenance has changed dramatically. These changes are due to a considerable increase in the number and variety of physical plant assets, increased design complexity, new maintenance techniques and changing perspectives regarding on how to perform maintenance effectively. Managers at modern process plants are becoming increasingly aware of the extent to which equipment failure affects safety and the environment. Process plant personnel are limited in their ability to accurately and consistently evaluate the health of plant assets. Due to poor record keeping, maintenance staff often has little defence against aging equipment and asset failures. As a result companies have undertaken to implement planned equipment maintenance schedules and install new technology to allow for efficient tracking and analysing of equipment health across the board. The introduction of an integrated asset management solution is presented in this thesis. The integrated asset management solution will assist maintenance staff to cost-effectively predict the probability of asset failure prior to the occurrence of any actual plant incidents. The integrated solution documented in this thesis will be implemented at the Sasol Solvents site to enhance plant availability, maximum up time for all plant assets and plant safety. Strategic Asset Management Inc. (SAMI) uses the Operational Reliability Maturity Continuum model to improve profitability, efficiency and equipment reliability. The SAMI empirical model employs various stages to address improved performance and asset management and was used as a guideline to develop an integrated solution to optimise plant performance and profits. The integrated asset management solution, documented in this thesis, was developed with the intended function of bringing information from diverse plant based systems and field equipment to the maintenance personnel in an understandable interface so that the information can be used to improve the reliability and availability of all plant assets.

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