Theses and Dissertations

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Advanced modelling of porous screens in aerodynamic diffusers using variable resistance factors
(2014-12) Janse van Rensburg, Jacobus Johannes; Van Staden, M. P.; Jacobs, G. G.
Strict emission legislation has forced industry in general to seriously consider the negative impact it has on the environment, specifically concerning emissions from burning fossil fuel into the atmosphere. In cases where emission levels exceed the allowable limit, companies are forced to operate at lower operating conditions and these load losses can result in a significant loss of revenue. This has forced companies to improve their ash filtering capabilities by optimising electrostatic precipitation systems. One of the main factors impacting on the efficiency of such a system is the distribution of the flow across the collection plates. The design of the inlet diffuser plays a major role in the ultimate distribution of the flow through the precipitator. Porous screens are positioned in the diffuser in order to distribute the flow across the total flow area with the aim to achieve a uniform distribution of the flow. CFD is widely used in industry to simulate the flow through precipitators in order to optimise the flow distribution and thus increase the efficiency of the system. It was found however that the current methods used to simulate these screens in CFD models were not well researched and employed fixed resistance values that could not reliably compensate for changes in the resistance coefficient due to a change in the angle of incidence. This study investigates advanced numerical methods for the simulation of porous screens in applications where the angle of incidence changes continuously across the face of the screen. New methods are introduced where the resistance of the screen is calculated as a function of the changing angle of incidence. The methods currently used are also investigated and compared with results from the new methods. Extensive experimental work was required to supply empirical data for the validation of the numerical methods that are proposed. For this reason, the first part of this study focused on the design construction and commissioning of a low speed wind tunnel. Results are presented and discussed for flow profiles through wide-angle diffusers at different angles and also for a number of different screens positioned in the centre of the diffuser. This study also investigates the sensitivity of a CFD simulation code to factors such as numerical discretisation schemes, turbulence models and solution relaxation specifically for wide-angle diffusers. These factors were tested for diffusers at different angles and included tests on open diffusers and also with screens positioned inside the diffuser. It was concluded that the current methods used are not adequate to capture the true flow profiles for a range of different screen geometries. Although the proposed models did improve on the limitations of the current methods, it was found that the applicability of these models is still limited and that further research would be required to develop numerical methods that are valid for a wide range of applications.
Anaerobic co-digestion of abattoir and textile industry wastewater in a UASB reactor
(2015-04) Ondari, James Maati; Ndege, Maurice S.; Aoyi, Ochieng
Textile industry effluents are carcinogenic and highly recalcitrant hence difficult to degrade especially through biological methods. Abattoir effluents are classified under high-strength wastewaters because of their characteristic high organic load hence highly biodegradable. Anaerobic co-digestion is the concept of degrading two effluent streams with complementary characteristics in order to improve the substrate removal rate. The feasibility of co-digesting abattoir and textile wastewater in a UASB reactor was evaluated at mesophilic and ambient temperature conditions. Preliminary experiments were conducted in 500 ml batch reactors to evaluate the optimum abattoir to textile synthetic wastewater ratio. The effect of COD, TVFA, alkalinity and pH on biogas yield was examined at both ambient and mesophilic temperatures. Anaerobic co-digestion of abattoir to textile wastewater in the ratio determined in the batch process was carried out in a 3 L UASB reactor by a continuous process. The continuous biodegradation process was executed at three different HRTs (22, 18 and 14 hrs) over a 60 day operation period. UASB reactor efficiency was achieved at organic loads ranging from 3.0 – 10.8 gCOD L-1 day-1. Continuous mode experiments were carried out at influent flow rates which corresponded to HRTs ranging between 1 to 8 days in order to evaluate the steady state operating parameters for the co-digestion process. The abattoir to textile effluent ratio was found to be 60:40 respectively. The COD, TVFA, alkalinity and pH and biogas yield followed a similar pattern over time at both mesophilic and ambient temperature conditions. Experimental data adequately fit the Grau first order kinetic model and average COD removal efficiencies of 85% and BOD5 of around 96% were achieved. The average biogas yield remained essentially constant, around 0.19 L/g CODremoved. The co-digested mixture was found to be biodegradable judging from the BOD:COD ratio of 0.53. TCOD removal efficiency decreased from 93% to 16% as HRT decreased from 8 days to 1 day. The kinetics of a UASB reactor co-digesting the mixture of synthetic abattoir and textile wastewater was evaluated in this study using Grau second order multicomponent substrate removal kinetic model. The Grau second order kinetic model, whose kinetic coefficient (ks) was 0.389, was found to be suitable for predicting the performance of a lab-scale UASB reactor.
An analysis of capital structures of listed industrial companies in South Africa
(2016-08) Popoola, Babatunde Adedeji; Beneke, J. D.; Ziemerink, J. E. E.
This study examines the capital structure theories, specifically the trade-off theory and the pecking order theory. It also analyses the influence of the capital structures choice among 72 listed industrial companies on the Johannesburg Stock Exchange ltd (JSE) in South Africa from 2005-2013 to determine whether these firms follow the trade-off theory or the peckingorder theory. The external database (INET BFA) was used to obtain the data needed for the statistical analysis. From the database, annual standardised financial statements, statement of comprehensive income, cash flow statements, financial ratios, statement of change in equity and the retained earnings to debt ratio of all the listed industrial companies in South Africa from 2005- 2013 were extracted in order to enable the conducted research. A multiple regression and correlation analysis were carried out the with leverage ratio (trade-off theory) and the retained earnings to debt ratio (pecking order theory) as the independent variables and share price as the dependent variable, in order to examine which of the two theories is closely related to share prices in South Africa. Furthermore, a multiple regression and correlation analysis was also done with common shares issued, retained earnings, long-term debt and weighted average cost of capital as the independent variables and share price as dependent variable, to determine if there is a relationship between the capital structure and share prices of the listed industrial company. The results indicated that there were little or no influence of capital structure theory on share prices, the financing practices and the performance of listed companies in South Africa. This indicated that industrial companies in South Africa rarely practice capital structure in accordance with the capital structure theories. Moreover, retained earnings and long-term debt have a positive influence on the performance of listed industrial companies in South Africa from 2005-2013.
An analysis of the cultural characteristics of the emerging black tourist market in Vanderbijlpark
(2013-07-18) Taylor, Tish Frances; Slabbert, E; Mwandla, M E
In recent years there has been a considerable interest in the cultural aspect of tourism (Reisinger & Turner 2003:1 ). Culture in its various forms and dimensions has a significant impact on tourism planning and development, management and marketing. Unfortunately literature that examines the impact of culture on tourism concentrates mostly on expressions of material forms of culture such as the arts, music, architecture or crafts. Research regarding the variables of national cultures such as values, perceptions, rules of behaviour and satisfaction has been neglected. The importance of cultural variables for tourist holiday experiences is important and affects satisfaction and consequently repeat visitation. Thus the cultural variables which influence the quality of the interpersonal interaction between tourists and hosts, can significantly add to tourist holiday experiences and satisfaction. The past few years has witnessed a dramatic change in the composition and nature of domestic tourism in South Africa (Futter & Wood 1997:1 ). Black tourists are emerging as the largest travelling group within South Africa and it is important to the tourism industry that cultural variables of this group be examined. Tourism has experienced a growing internationalization and considerable attention has been paid to the issue of cultural diversity as a result of this growth in international travel. Tourism is a service industry where people from all nationalities meet and the crossing of different cultures takes place. This cross-cultural interaction leads to socio-cultural impacts which affect both the tourist and the host community. By understanding the cultural characteristics of various travelling groups to and around South Africa, socio cultural impacts will be minimised and the benefits of tourism can be appreciated. The target group for this study was black tourists to Vanderbijlpark. This is a large domestic tourism group and understanding the cultural characteristics of this group will enable the tourism industry to better plan, develop and market specific tourism packages. Research for this study was undertaken at a jazz festival in Vereeniging. Field workers randomly interviewed respondents using a questionnaire. The questionnaire consisted of five sections, namely demographic particulars, personal values, rules of behaviour, perceptions and satisfaction. The data was analysed to provide information regarding the cultural characteristics of the black tourism market in Vanderbijlpark. Respondents were categorised using the demographic data, the culture sections of the questionnaire were analysed in order to give descriptive results of each of the cultural variables. Each variable was analysed to determine its importance to respondents, thus categorising respondents according to their cultural characteristics. A factor analysis was completed in order to synthesise the large amount of data and for each cultural variable smaller, more descriptive factors were identified and used to describe the black tourism market in Vanderbijlpark.
Analysis of the environmental impact on the design of fuel cells
(2013-08-22) Sibiya, Petros Mandla; Pienaar, H. C. v Z
The air-breathing Direct Methanol Fuel Cell (DMFC) and Zinc Air Fuel Cell (ZAFC)were experimentally studied in a climate chamber in order to investigate the impact of climatic environmental parameters such as varying temperature and relative humidity conditions on their performance. The experimental results presented in the form of polarization curves and discharge characteristic curves indicated that these parameters have a significant effect on the performance of these fuel cells. The results showed that temperature levels below 0ºc are not suitable for the operation of these fuel cells. Instead, it was found that air-breathing DMFC is favored by high temperature conditions while both positive and negative effects were noticed for the air-breathing ZAFC. The results of the varying humidity conditions showed a negative impact on the air-breathing DMFC at a lower temperature level but a performance increase was noticed at a higher temperature level. For air-breathing ZAFC, the effect of humidity on the performance was also found to be influence by the operating temperature. Furthermore, common atmospheric air pollutants such as N20, S02, CO and N02 were experimentally investigated on the air-breathing DMFC and ZAFC. At the concentration of 20 ppm, these air contaminants showed to have a negative effect on the performance of both air-breathing DMFC and ZAFC. For both air-breathing DMFC and ZAFC, performance degradations were found to be irreversible. It is therefore evident from this research that the performance of the air-breathing fuel cell will be affected in an application situated in a highly air-polluted area such as Vaal Triangle or Southern Durban. It is recommended the air-breathing fuel cell design include air filters to counter the day-to-day variations in concentration of air pollutants.
Application of integrated water resources management in computer simulation of River Basin's status - case study of River Rwizi
(2012-03-28) Atim, Janet; Ngirana-Katashaya, G.; Ndambuki, J. M.
During the last few years, concern has been growing among many stakeholders all over the world about declining levels of surface water bodies accompanied by reduced water availability predominantly due to ever increasing demand and misuse. Furthermore, overexploitation of environmental resources and haphazard dumping of waste has made the little water remaining to be so contaminated that a dedicated rehabilitation/remediation of the environment is the only proactive way forward. River Rwizi Catchment is an environment in the focus of this statement. The overall objective of this research was to plan, restore and rationally allocate the water resources in any river basin with similar attributes to the study area. In this research, Integrated Water Resources Management (IWRM) methodology was applied through Watershed/Basin Simulation Models for general river basins. The model chosen and used after subjection to several criteria was DHI Model, MIKE BASIN 2009 Version. It was then appropriately developed through calibration on data from the study catchment, input data formatting and its adaptation to the catchment characteristics. The methodology involved using spatio-temporal demographic and hydrometeorological data. It was established that the model can be used to predict the impact of projects on the already existing enviro-hydrological system while assigning priority to water users and usage as would be deemed necessary, which is a significant procedure in IWRM-based environmental rehabilitation/remediation. The setback was that the available records from the various offices visited had a lot of data gaps that would affect the degree of accuracy of the output. These gaps were appropriately infilled and gave an overall output that was adequate for inferences made therefrom. Several scenarios tested included; use and abstraction for the present river situation, the effect of wet/dry seasons on the resultant water available for use, and proposed projects being constructed on and along the river. Results indicated that the river had insufficient flow to sustain both the current and proposed water users. It was concluded that irrespective of over exploitation, lack of adequate rainfall was not a reason for the low discharge but rather the loss of rainwater as evaporation, storage in swamps/wetlands, and a considerable amount of water recharging groundwater aquifers. Thus, the proposed remedy is to increase the exploitation of the groundwater resource in the area and reduce the number of direct river water users, improve farming methods and conjunctive use of groundwater and surface water - the latter as a dam on River Rwizi. The advantage of the dam is that the water usage can be controlled as necessary in contrast to unregulated direct abstraction, thus reducing the risk of subsequent over-exploitation.
An application of reverse osmosis process on effluent treatment for the rubber industry
(2009-05) Ralengole, Galebone; Van der Merwe, H.; Modise, S. J.
The methods used to remove potassium sulphate (K2S04) and other impurities contained within Karbochem finishing plant effluent were investigated. Reverse osmosis was explored for this application. The study was conducted in two steps. The first step focuses mainly on the effluent treatment using BW30 flatsheet as well as BW30-2540 spiral-wound reverse osmosis membranes for the rejection of potassium and sulphate ions. The membranes were supplied by Filmtec. The second step reveals the possible use of potassium sulphate obtained from the brine stream in the fertiliser and fertigation industry by a literature search. Reverse osmosis study was conducted on a laboratory scale unit using flat sheet membranes and also on a pilot plant scale using spiral wound membrane modules. The tests were conducted at a feed pressure of 20 bar(g) with the membrane rejections being 98% and 99.1% on flat sheet membrane, and 96.9% and 99.4% on spiral wound membrane for potassium and sulphates respectively. The results show that both membranes have completely desalinated. Significant reduction in the concentrations of all problematic quality parameters, especially of potassium and the sulphate ions was noted. Granular activated carbon (GAC) bed treatment was recommended for pretreatment of the effluent prior to exposure of the membrane to avoid organic fouling of the membrane. GAC treatment was tested to illustrate its effectiveness to adsorb the COD's.
Assessing the genetic diversity of Alternaria Bataticola in South Africa using molecular markers
(Vaal University of Technology, 2015) Chalwe, Joseph Musonda; Adebola, Patrick, Dr.; Pillay, Michael, Prof.
Sweetpotato (Ipomoea batatas) is an important food crop that is grown in many countries. A number of viral and fungal sweetpotato diseases have been reported worldwide. One of the major and most economic diseases of the sweetpotato is Alternaria blight which is caused by the fungal pathogen Alternaria bataticola. This disease can be managed in a short term using fungicides and cultural practices. However, a long term and inexpensive approach is through the development of resistant cultivars. A prerequisite to this approach is the knowledge of the genetic diversity of this fungal pathogen. This study assessed the genetic diversity of 25 South African isolates of A. bataticola from naturally infected leaves and stems collected from different sweetpotato growing regions in South Africa by (i) characterising the isolates based on their morphology (ii) pathogenicity tests (iii) random amplified polymorphic DNA (RAPD) (iv) variation of the ITS2 sequences and (v) prediction of the ITS2 secondary structures. The isolates revealed some variation in colony colour pigments after culturing but Koch’s postulates were confirmed by their pathogenicity tests. The analysis of RAPD and variation of the ITS2 sequences showed high levels of variation (100%) among the isolates. Dendrograms generated from these analyses had many subclusters and did not cluster the isolates according to their geographic origins. The ITS2 secondary structures were predicted and can be used to identify and distinguish the isolates. This information in addition to the genetic diversity of the A. bataticola isolates will aid plant breeders in the development of resistant sweetpotato cultivars and early management of blight disease in South Africa.
Assessing the genetic diversity of South African sweetpotato germplasm using DNA and protein markers
(Vaal University of Technology, 2013-06) Selaocoe, Maleshoane Ellen; Adebola, Patrick, Dr.; Pillay, Michael, Prof.
Sweetpotato is one of the most important food crops in developing countries including South Africa. Currently two major types of cultivars are grown in South Africa: one is the orange-fleshed sweetpotato (OFSP) which has high β-carotene content, a precursor of vitamin A. The second type is the cream-fleshed sweetpotato (CFSP) which has low β-carotene content but is high in dry matter. Most South Africans prefer the CFSP although the OFSP offers more advantages. This presents a challenge to plant breeders to develop new varieties that will combine the desirable qualities of both the cultivars. To achieve this goal, plant breeders need knowledge about the genetic variation of the crop to develop an efficient breeding programme. This study assessed the genetic relationships of 28 orange- and cream-fleshed sweetpotato accessions by (i) examining the variation in leaf proteins, (ii) using random amplified polymorphic DNA (RAPD) and, (iii) using variation of the ITS region. The analysis of proteins, RAPD and variation of the ITS region polymorphism levels were 55.6%, 98% and 16.5%, respectively. Dendrograms generated from all the analyses generally clustered the accession according to their flesh colour and country of origin. Analysis of molecular variance (AMOVA) found a significant difference between OFSP and CFSP and a significant difference between the South African and non-South African germplasm. The high genetic diversity in the South African sweetpotato germplasm is a positive indicator for a breeding programme that has a number of targets such as breeding for nutritional improvement, disease resistance and drought tolerance
Characterisation of Amaranthus Tricolor mutant plants with increased drought-tolerance
(Vaal University of Technology, 2010-02) Kgang, Itumeleng Eugenia; Van Emmenis, Lynelle, Dr.; Laloo, Neelan
Amaranthus tricolor (A. tricolor) is a nutritious vegetable crop that is used as a subsistence and cash crop in the rural areas in Africa. Its yield and production is severely limited by abiotic stresses such as drought. Mutation technology, using gamma irradiation, was previously employed as a tool to create genetic variation in order to select for lines with improved drought-tolerance. During irradiation, 160 Gy (Gray) was selected as the optimal dosimetry that allowed subsequent seed germination. The resulting mutant lines were screened over several generations under field and greenhouse conditions and seven promising drought-tolerant lines were selected. Here we report on physiological and morphological studies of two of these Amaranthus mutant lines (#2 and #5) to confirm the enganced drought-tolerance. Plants were grown in the greenhouse in plastic pots containing germination mix with fertiliser. They were exposed to 21 days of well-watered condition, 19 days of drought-stress conditions and 7 days of re-watering. shoot height, leaf area, protein content and relative water content (RWC) of the fresh and dry material were determined colorimetrically under well-watered and drought-stress conditions, while anthocyanin was only measured during well-watered conditions. Shoot height, leaf area, number of leaves per plant and the protein content were significantly reduced under water-stress conditions. Under well-watered condition mutant #5 grew faster with the shoot length significantly higher than mutant #2 and the wild type. Even though drought adversely affected shoot lenght, mutant#5 still performed better than mutant #2 and the wild type under drought-stress conditions. While under both well-watered and drought-stress conditions, the wild type plants had bigger leaf area compared to the two mutant lines. After 16 days of drought-stress conditions, all the leaves of the wild type plants were dried out, as a result no wild type plants recovered after 8 days re-watering. Meanwhile, both mutant #2 and #5 plants recovered significantly after 8 days of re-watering. The wild type was tolerant compared to the two mutant lines. Protein content for mutant #2 plants was higher under both well-watered and drought-stress conditions but was not significantly different from mutant #5 plants compared to the wild type plants after 19 days of drought-stress conditions. Furthermore, genetic diversity was examined in all the Amaranthus lines using random amplified polymorphic DNA (RAPD) analysis. Nineteen arbitrary RAPD markers were used of which two detected polymorphisms (OPA) 07 and OPA 16).
Characterization and identification of microbial communities in pigeon droppings using Culture-Independent techniques
(Vaal University of Technology, 2015-08) Leareng, Samuel Keeng; Feto, Naser Aliye, Dr.; Pillay, M., Prof.
Pigeon droppings, found in abundance in most cities and towns where pigeons are found, are a source of potential yeast and molds into the environment. Invasive fungal infections are a cause of morbidity and often mortality in immunocompromised individuals. The objective of this study was to the identification of bacterial and mold agents from pigeon droppings. Pigeon droppings samples were collected from three locations during the winter and summer months and studied for the occurrence of bacteria, yeast and molds by utilising culture-independent techniques. Amplification of the 16S rDNA gene and the internal transcribed spacer (ITS) region, cloning and ARDRA and DGGE were used for the characterisation of the microbial populations followed by sequencing. Several mold and yeasts, as well as bacteria were found to be present in pigeon droppings, which can spread into the environment and be transmitted to immunocompromised individuals and children. DGGE analysis of the bacterial communities revealed banding patterns that clustered all but one winter samples and all summer samples, showing a high similarity among the microbial members in both seasons and sample locations. Fungal DGGE analysis revealed clusters that grouped summer and winter samples from Johannesburg and Pretoria while VUT samples were clustered on their own. From the identification of fungal and bacterial DNA, Cryptococcus species was the majority of fungi isolated from the dropping samples. Geotrichum, Kazachstania and Fusarium species were isolated from phylotypes obtained from ITS amplicons analysed by ARDRA. Lactobacillus and Enteroccoccus species, organisms usually found in the gastrointestinal tract were the common bacterial members identified. The results showed no difference in microbial communities across all sample locations, while seasonal changes also had no impact in microbial community patterns.
Co-production of inulinase by Kluyveromyces marxianus and Saccharomyces cerevisiae in solid state fermentation
(Vaal University of Technology, 2014-02) Molefe, Nnana Mantsopa; Reddy, P.; Padayachee, T., Prof.
Solid-state fermentation (SFF) has emerged as a good method for the production of microbial enzymes such as inulinases. The use of low-cost agricultural plants and agro-industrial residues as substrates in SSF processes provides a value adding alternative to these otherwise under/or un-utilised vegetation. Production of inulinases, using various inulin-containing plant materials as carbon sources was studied using pure and mixed cultures of yeast strains. All substrates resulted in different levels of enzyme activity. A mixed culture of Kluyveromyces marxianus and Saccharomyces cerevisiae produced an extracellular exoinulinase when grown on different types of inulin-containing plant materials. Initial inulinase production was achieved as follows: 10 IU/gds (garlic cloves), 15 IU/gds (parsnips), 10 IU/gds (wheat bran) and 7 IU/gds (amadumbe) by K. marxianus and S. cerevisiae in a mixed culture. The production of inulinases by a mixed culture of K. marxianus and S. cerevisiae under SSF was further optimized by investigating initial moisture content, temperature, carbon source, nitrogen source, inoculum volume and inoculum ratio. The highest inulinase activity attained was in garlic cloves (85 IU/gds), followed by parsnips (65 IU/gds), wheat bran (37 IU/gds) and amadumbe (25 U/gds). The activities yielded 5.6 fold higher inulinase than in preliminary studies. The optimum pH and temperature of the crude enzyme were 5.0 and 50 oC, respectively. The pH and temperature stability of the enzyme was steady for 1 hour retaining about 64% activity. The average inulinase/invertase activity (I/S) ratio of 1.0 by crude inulinases was also observed after 48 hours. The crude extracellular enzyme extracts from the garlic cloves, parsnips, amadumbe and wheat bran were partially purified by ammonium sulphate precipitation and showed a specific activity of 9.03 U/mg, 0.08 U/mg, 4.12 U/mg and 0.133 U/mg respectively. The Km and Vmax values of the inulinase were 21.95 mM and 2.09 μM/min; 19.79 mM and 1.38 μM/min; 31.59 mM and 0.51 μM/min; and 25.74 mM and 0.23 μM/min, respectively. All extracts demonstrated potential for large-.scale production of inulinase and fructose syrup.
Cobalt and cadmium chalcogenide nanomaterials from complexes based on thiourea, urea and their alkyl derivatives : synthesis and characterization
(2015) Morifi, E. L.; Moloto, M. J.; Matabola, K. P.
Cadmium and cobalt complexes of urea and thiourea were synthesized using ethanol as a solvent. All complexes were refluxed at 70 - 80 °C, left to cool at room temperature, washed with methanol and acetone to remove impurities and dried at an open environment. The characterization of complexes was done using FTIR spectroscopy, elemental analysis and TGA. The complexes were found to coordination with the ligands through sulphur and oxygen atoms to the metal, instead of nitrogen. These were as results of wavelength shifting from high to low frequency from spectra of the complexes as compare to their free ligands. These observations make these complexes good candidates for the possible use in synthesis of metal sulphides or oxides nanoparticles. Thermogravimetric analyses of all the complexes were conducted to check the stability of use as precursors for nanoparticles at low and high temperature. A number of thiourea and urea complexes with cadmium and cobalt have been prepared and used in the preparation of metal sulphides/oxides nanoparticles. Complexes start to decompose at low temperature about 100°C and the last decomposition step was at about 800-900°C, which is convenient to thermal decomposition of precursors in the high boiling solvents or capping agent to prepare surface capped metal sulphides/oxides nanoparticles. The complexes were easy to synthesize, low cost and stable in air and were obtained in reasonable yields. All the complexes reported in this study have been used as single source molecular precursor in the preparation of cadmium oxide, cadmium sulphide, cobalt oxide, cobalt sulphide nanoparticles (normal) and as mixture of any two complexes to form core-shells nanoparticles. Quality nanoparticles synthesis requires three components: precursors, organic surfactants and solvents. The synthesis of the nanoparticles can be thought of as a nucleation event, followed by a subsequent growth period. Both the nucleation and growth rates were found to be dependent upon factors such as temperature, growth time, and precursor concentration. For a continuous flow system the residence time (at nucleation and growth conditions) was also found to be important. In order to separate the nucleation and growth events, injection techniques were employed to achieve rapid nucleation of nanoparticles with final size dictated by the growth temperature and/or residence time through the growth zone of the reaction system. Good crystalline normal nanoparticles were obtained from thermolysis of the precursors in hexadecylamine (HDA) as the capping agent at fixed concentrations, temperature and time. All nanoparticles showed a blue-shift in band edges with good photoluminescence behaviour which is red-shifted from their respective band edges and XRD patterns, the crystal structure are in hexagonal phase. The particles showed rods, spheres and hexagonal shapes. Nucleation and growth mechanism brings new avenue in nanostructures called core-shells, which have been reported to have improved luminescence, quantum yields, decreased fluorescence lifetimes, and benefits related to the tailoring of the relative band-gap positions between the two materials. In this study cadmium and cobalt complexes of urea and thiourea were separately dispersed in TOP and injected separately (allowing nucleation/core to occur, followed by the shell) in hot HDA at 180ºC for 1hour to yield core-shell nanoparticles. Parameters, such as concentration, temperature and capping molecule as factor affecting nucleation and growth of the core-shells were monitored. The core-shell nanoparticles were characterized by UV/Vis spectroscopy, XRD and TEM. We observed spherical, tripod, bipods, hexagonal and irregular shaped nanoparticle as the concentration of the precursors was increasing, however we were able to form core-shells nanoparticles in one set of experiment 1:3 CdS-CdO, which are assumed to be a reverse type I coreshells nanoparticles. Exciton absorption peaks at higher energy than the fundamental absorption edge of bulk indicate quantum confinement effect in nanoparticles as a consequence of their small size. XRD patterns, crystals range from hexagonal, cubic and mixture of hexagonal and orthorhombic. A low temperature studies were also conducted a mixture of hexagonal and sphererical shapes with sheets like onion morphology were observed.
The cognitive impact of the implementation of an entry level certificate in information technology
(2013-07-18) Van Staden, Corne Johandia; Du Plessis, Linda; Janse van Rensburg, Gail
Research has found that learners find it difficult to solve programming problems in a logical way, therefore the failure rate in Programming I is high. The Entry-level Certificate in Information Technology was introduced as an intervention to address this problem. Four aspects were focused on in the Entry-level Certificate in Information Technology, namely English comprehension, academic competency, numerical skills and the problem-solving skills of learners. Basic computer literacy was the common theme used throughout the Information Technology Boot Camp (ITBC) to address the above-mentioned aspects, in order to broaden access to the Vaal University of Technology (VUT). The research indicates that English comprehension is a very important component of the Information and Communication Technology (ICT) modules, and that it is important for learners to have an English proficiency level of grade 12 before enroUing for a diploma in I CT. The ICT and numerical skills modules also narrowed the gap between secondary and tertiary education, by equipping the learners with prior knoWJledge that is crucial for being successful in the ICT diploma. To conclude access was broadened to the VUT and the intervention of the ITBC did impact positively on the cognitive functioning of learners.
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.
Comparative analysis of five different school feeding strategies in the Vaal region
(2010-07-22T06:37:51Z) Kearney, Jeanette Emmerentia
School feeding programmes are defined as interventions that deliver a meal or snack to children in the school setting, with the intent of improving attendance, enrolment, nutritional status and learning outcomes. The Primary School Nutrition Programme (PSNP) was introduced in South Africa as a Presidential Lead Project in 1994 with the specific aim to improve education by enhancing active learning capacity, school attendance and punctuality. However, not all children qualify to participate in the PSNP and a variety of alternative products, of which little information is known, are used as part of school feeding programmes implemented by non-governmental organizations (NGOs). The aim of this study was to investigate such programmes used in the Vaal Region. Five different products used in school feeding programmes in a primary school in Eatonside and two primary schools in Orange Farm were compared in terms of the nutritional content of the products, the impact of these products after a seven month intervention on the nutritional status of the children by analysing their dietary intakes as well as biochemical and anthropometrical measurements, menu cost, compliance of the products by conducting sensory analyses and shelf life studies, and the impact on school attendance. Based on the results of this study, guidelines on the optimal school feeding strategy would be provided to NGO’s and to the Gauteng Department of Education. The five products were a micronutrient dense “vetkoek”, PSNP, two commercial products namely Corn Soya Blend (CSB) and Sejo and, lastly, fruit, which was used as the control. In the Sethlabotja school in Eatonside, the sample consisted of 160 randomly selected boys and girls (40 children participating in the PSNP, and 60 children in each of the vetkoek and fruit groups) and in Sinqobile and Reitumetse schools in Orange Farm the sample included 45 randomly selected children in each of the CSB and Seja groups. Pre-intervention results indicated poor nutritional status. Mean daily energy intake of all the children was below the Dietary Reference Intakes for children between seven and ten years. A mainly carbohydrate-based diet was followed, with inadequate fruit and vegetable intake. The anthropometric indices indicated acute and chronic food shortage. The biochemical results indicated that normal values were present for the majority of the parameters. The post-intervention results indicated that the food consumption patterns did not change substantially during the intervention but the mean energy intake of the children as well as weight, height and body mass index increased with all the interventions. Although few statistically significant differences were observed between the five groups with regard to nutritional status indices, positive changes were observed in each of the groups. The products evaluated in this study proved to be within the range of the provincial school feeding budget. CSB and Sejo were the cheapest programmes because they are subsidised. Compliance to the products was good. No significant differences between commercial and home-prepared food items were found. School attendance was not formally recorded in all the groups. However, a decrease in absenteeism was noted in those groups where it was recorded. It is recommended that further research is conducted on the impact of school feeding on the cognitive performance of school learners in the Vaal Region.
A comparative analysis of the effective use of transfer pricing policies in multinational manufacturing corporations in Southern Gauteng
(2016-04) Siewe, Constantain Lendeu; Ziemerink, J. E. E.; Beneke, J. D.
This study was undertaken to assess the extent to which transfer pricing was effectively used by multinational manufacturing companies operating in the Southern Gauteng region of South Africa. The target participants of the study traded their products across international borders and as such made use of transfer pricing in one way or the other to achieve strategic objectives. Scant research has been undertaken to analyse the degree to which transfer pricing can be used to effectively influence managerial performance. On the other hand there is a wealth of knowledge on the relationship between transfer pricing and taxation. In-depth review of literature showed that even though multinationals formulated their transfer pricing policies to target financial and managerial objectives, self-interest and outside influences tended to hinder the equitable realization of both types of objectives. The study therefore set out to establish whether this is true of Multinational corporations (MNCs) in Southern Gauteng and in the process answer questions about the procedure for formulating transfer pricing policies by these MNCs, the relationship, if any, between transfer pricing and profitability and the use of transfer pricing for performance enhancement and assessment. The study made use of a mixed methods research methodology to collect and analyze data from 45 MNCs operating in the target geographical area. Of the 45 companies, 15 cooperated fully with the study. Data was collected via the use of questionnaires and follow-up face-to-face and/or telephonic interviews. Collected data was analysed using statistical methods including the Chi Square Test, standard deviation, frequency tables and the Kruskal-Wallis H test. The results from the questionnaire and interviews show that there is no universally appropriate Transfer Pricing Policies(TPP) which applies equally to all organizations in all circumstances. Firms are affected by different environmental factors while striving for tax-compliance and value creation. The fear of falling on the wrong side of tax laws is a major driving force behind transfer pricing policies of MNCs. As such other objectives that are managerial in nature become secondary and tend to be neglected if/when they conflict with the primary objective.
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.
The construction and evaluation of a novel tubular photobioreactor at a small pilot plant scale
(Vaal University of Technology, 2012-07) Kutama, Makonde; Van Wyk, C.; Stegmann, P., Dr.
The mass production of algae for commercial purposes has predominately been carried out in open ponds systems. However, open ponds systems have a number of disadvantages such as poor light utilization, requirement for large areas of land and high risks of contamination. On the other hand, photobioreactors have attracted much interest because they allow a better control of the cultivation conditions than open systems. With photobioreactors, higher biomass productivities are obtained and contamination can be easily prevented. Photobioreactors can also be engineered to manipulate the light and dark photosynthetic reactions thus enhancing biomass productivity. The main objective of this study was to construct a novel tubular photobioreactor which had the ability to expose the cultured alga to light and dark phases with the aim of optimizing the algal biomass production. A novel tubular photobioreactor with the ability to manipulate the cultured alga’s light and dark photosynthetic reactions was constructed in this study. The alga Spirulina platensis was chosen as the test organism in this novel tubular photobioreactor due to a number of reasons such as its globally socioeconomic importance, its tolerance of higher pH and temperature values which makes it almost impossible to contaminate. The cultivation process of Spirulina in the photobioreactor was investigated through alternating light and dark cycles in an attempt to increase the photosynthetic efficiency of the culture. The effect of different light intensities on the growth of Spirulina in the novel tubular photobioreactor was investigated and it was found that the best light condition that favored higher biomass formation was at 600 μ mol m-2 s-1. Five different light/ dark ratios were evaluated at a light intensity of 600 μ mol m-2 s-1 during a batch mode of operation of the novel tubular photobioreactor. The light/ dark ratio of 1:0.25 was found to be the best ratio because it gave the highest biomass in the shortest period of time when compared to the other ratios used. These results seem to suggest that longer light cycle relative to dark cycle results in higher biomass production. The ratio of 1:0.25 was then used to operate the novel tubular photobioreactor in a continuous mode. A maximum biomass productivity of 25 g/m2/day was achieved which corresponded to a net photosynthetic efficiency of 5.7 %. This result was found to be higher than what most photobioreactors could achieve but it was 2.8 g/m2/day lower than the highest ever reported productivity in a photobioreactor when Spirulina is cultivated. The 2.8 g/m2/day lower was attributed to the different materials used in the construction of these two photobioreactors. The photobioreactor which achieved 27.8 g/m2/day was made up of a clear glass whereas the novel tubular photobioreactor was made up of a PVC tubing. PVC tubes tend to change from clear to a milky colour after a certain period when it is used at higher temperature and pH values hence blocks a certain amount of light. Therefore the main recommendation in this study is to use a PVC tubing with a longer life span when used at a higher temperature and pH values.
A constructive analysis of safety control mechanisms and production costs at a coal mine
(2016) Mokoena, Mothemba Cecilia; Oberholzer, Merwe; Joubert, Deidre
Statistics in South Africa show that the fatality and injury rates within the mining industry have dropped since the end of the apartheid era. Regardless of the drop the fact remains that the mine workers, who are often the breadwinners, are still dying in the country’s mines leaving their families behind without any source of income. If they do not die they may suffer crippling injuries due to mine accidents making it impossible for them to perform their daily duties at work which results in the loss of income, loss of quality of life and this produces a humanitarian and a socio-economic problem. Mining companies incur enormous costs due to fatalities and injuries. Hence a target for zero fatalities was set in the mining industry for 2013. However, the industry has failed to reach this target that it set for itself and it is therefore of the utmost importance to encourage mining companies to invest more than they do currently in safety in order to prevent these fatal and crippling injuries due to mine accidents. The purpose of this study was to determine whether or not the requirements of safety legislation are observed and complied with by a single Colliery in South Africa that was selected for this study. The study also sought to investigate whether or not the employees of this mine observe the safety regulations to ensure safety and to maintain an accident free working environment. An analysis of organizational safety control mechanisms and production cost was conducted through the use of a structured questionnaire, completed by 151 participants. Descriptive statistics, frequency tables, exploratory factor analysis (EFA), one-way analysis of variance (ANOVA) and t-test were utilized to analyse the data. The results indicate that the Colliery was compliant with the safety legislations, a positive employee safety attitude had been cultivated and there was provision of adequate safety facilities through safety investments. Cost reduction due to the application of safety controls was also established, yet it was found necessary for the Colliery to enforce and encourage the application of safety measures to reduce the costs that are still incurred as it is evident that the application of safety controls results in reduced costs. Although the Colliery was considered compliant, with its employees showing a positive attitude towards safety controls, and with safety investments made and cost reduction achieved due to safety measures, ANOVA revealed different perceptions based on the departments in which the employees work, years of experience, English proficiency and qualifications. However, no differences were found in relation to gender and designation.

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