Showing items 941 - 960 of 1292

Your selections:

The distribution and diversity of macroalgae in selected estuaries along the Eastern Cape coast of South Africa

  • Authors: Prinsloo, Shireen
  • Date: 2012
  • Subjects: Estuarine ecology -- South Africa -- Eastern Cape , Algal communities -- South Africa -- Eastern Cape , Marine plants -- Economic aspects -- South Africa -- Eastern Cape , Estuarine area conservation -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10631 , http://hdl.handle.net/10948/d1012314 , Estuarine ecology -- South Africa -- Eastern Cape , Algal communities -- South Africa -- Eastern Cape , Marine plants -- Economic aspects -- South Africa -- Eastern Cape , Estuarine area conservation -- South Africa -- Eastern Cape
  • Description: The growth and accumulation of macroalgae in estuaries are a common sight throughout the world (Boyer and Fong, 2005). Because macroalgae establish such complex but important links with other components within an estuary, it is essential to know which variables control and regulate their occurrences. The type of algae that will occur in an estuary depends however, on the physical and chemical features of the particular estuary (Lobban and Harrison, 1994). The focus of this study was to document and provide a listing of algae from estuaries around the Eastern Cape coast of South Africa and describe the communities which form within each estuarine habitat. The questions posed were: Do algae assemblages differ in estuaries with different environmental conditions? Are different plant communities inhabited by different algae communities? Also, are algae diverse in estuaries that are in a pristine condition? The estuaries were Mngazana, Ngqusi/Nxaxo, Mtati, Mpekweni, East Kleinemonde, West Kleinemonde, Kariega, Bushmans, Kowie and the Sundays estuary. Percentage cover surveys were conducted and environmental parameters recorded to determine community structure of algae and their environmental tolerances. A total of 49 different macroalgal species were identified from 11 estuaries, which were dominated by Chlorophytes (23 species) and Rhodophytes (17 species). The Ochrophytes consisted of 10 species. The highest number of species recorded was 29 at the Bushmans estuary (March 2009), while the lowest number (4 species) was recorded at Mtati (October 2008). Common Chlorophytes found included Ulva prolifera, Chaetomorpha linum and Codium tenue. In the Division Ochrophyta, species from the Genus Ectocarpus were the most common. Of the red algae filamentous reds, Polysiphonia incompta and Polysiphonia kowiensis were the common algae found at estuaries. Salinity (p= 0.029861; n= 49) and temperature (p= 0.037641; n= 49) were the driving environmental parameters of estuaries and significantly influenced richness of species. In ordination analyses, patterns of biogeographic distribution were noticeable and were described by salinity. Four gradients caused by salinity were therefore found – which is inversely correlated to water clarity. Moreover, a clear split between temporarily open/closed and the permanently open estuaries was observed. Samples grouped into four communities presumably based on the similarity in conditions of estuaries. Within each estuarine community and major type of estuary there was a range of environmental conditions. However, the macroalgae within each community may not have been colonists of or found in greatest abundances in the estuaries of these communities per se, but may have grouped together in this manner based on the optimum growing conditions for them. Also, specific algal groups were not directly determined by the type of estuary they were found in; they were driven by environmental ranges rather. The results therefore support hypothesis one which states species distribution and diversity differ and are influenced by environmental gradients of the estuary. Although close species and habitat relationships were apparent from the ordination analyses, providing support for hypothesis two which states “Different plant communities in estuaries will be inhabited by different macroalgae communities”, the evidence was not substantial enough to provide sufficient support for the hypothesis. Lastly, the hypothesis “Macroalgae are diverse in estuaries that are in a pristine condition” was not accepted as highest species numbers were found in estuaries of greatest anthropogenic disturbance (e.g. Bushmans estuary) and not in estuaries which where ecologically more natural (e.g. Mtati estuary). By doing monthly macroalgal sampling over a period of one year for example one would obtain greater information of biodiversity, and patterns of macroalgal seasonality may be uncovered as well. This is an area of reasearch which needs to be investigated in the future as it would greatly add to the understanding of the role macroalge have in an estuarine environment.
  • Full Text:
  • Date Issued: 2012

The effectiveness of agricultural extension as perceived by small scale farm holders

  • Authors: Olufayo, Ayowumi Motunrayo
  • Date: 2012
  • Subjects: Agricultural extension work -- South Africa , Agriculture -- South Africa
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: vital:10592 , http://hdl.handle.net/10948/d1019765
  • Description: Empirical studies have suggested that agricultural extension can increase agricultural productivity. However, the increase in productivity is dependent on a number of issues. As a result, this particular study was conducted among farmers in order to examine the relationship between the provision of extension services and increased productivity in a regional context. The perceptions of vegetable home gardeners resident in the Nelson Mandela Metropolitan area, who participated in the Siyazondla Homestead Production Programme, formed the source of the primary data. The views of these farmers were analysed to determine how extension services affected their performance. The findings revealed that the farmers have a good perception of the extension services, although this negatively correlates with their level of performance. In addition, the data indicate that farmers who had a poor perception of extension services tend to achieve high production while those with a good impression of services had a poor performance. It was however observed that level of education, farming experience and exposure to print media influenced the responses that were captured in the study.
  • Full Text:
  • Date Issued: 2012

The effects of salinity and inundation on salt marsh plants in the context of climate change

  • Authors: Tabot, Pascal Tabi
  • Date: 2012
  • Subjects: Salt marsh plants -- Climatic factors , Plant ecophysiology
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:10637 , http://hdl.handle.net/10948/d1019919
  • Description: Ecophysiology studies are needed to predict plant responses in relation to climate change. Variations in salinity and inundation are expected to influence the survival and distribution of salt marsh. The following species were chosen to study as they occur in most South African salt marshes and are representative of different tidal ranges; namely Triglochin buchenaui (lower intertidal), Bassia diffusa (upper intertidal succulent) and Limonium linifolium (upper intertidal non-succulent). To simulate climate change conditions as predicted for South Africa, a 3 x 5 controlled experiment of three inundation levels (tidal, submerged and drought) and five salinity levels (0, 8, 18, 35, 45 ppt) was conducted for each species. This resulted in 15 treatments per species. Plant responses were measured over a three month period. Triglochin buchenaui showed significant variation in height (7.57 ± 0.5 to 29 ± 1.55 cm, p < 0.005, DF = 55) with optimum growth at 0 ppt under tidal conditions; leaf area increments and relative growth rates which decreased with increasing salinity under all inundation states. There was almost a cessation of growth under submergence which reduces the plant’s regeneration potential under these conditions. Proline accumulation (1.84 ± 0.23 to 3.36 ± 0.38 mg l-1), response of photosynthetic pigments and electrolyte leakage (8.17 ± 0.80 to 38.36 ± 7.42 percent) were fundamental to osmotic and membrane response regulation. Plants survived in all inundation states at salinity up to 45 ppt, but the optimum range was 0 to 18 ppt, and best water state was the tidal condition. Viable rhizomes were produced under drought conditions. Bassia diffusa (Thunb.) Kuntze plants under submergence died within one month, irrespective of the salinity. Optimum growth occurred in plants of the tidal treatment at 18 ppt, and reduced with increased salinity and drought conditions. Plants in the tidal treatments were more succulent than the drought-treated plants. There was reduced leaf mass and high anthocyanin concentrations in drought-treated plants and these effects increased with salinity. Soil and leaf water potential were positively correlated with anthocyanin concentration in leaves and stems, suggesting anthocyanin accumulated in response to drought and could be an adaptation to lower the plant’s water potential under drought conditions. A shift of anthocyanin from leaves to stems was found in drought-treated plants, and this possibly enables the maximization of photosynthesis in leaves, to complement its role in osmotic balance and photo-protection. Growth of Limonium linifolium showed that the plant was tolerant to a wide range of salinity under both tidal and drought conditions, but was susceptible to complete submergence, with high membrane damage even in tidal-treated plants. Plants died within 2 weeks of complete submergence. Results further indicated that L. linifolium tolerates extreme drought by accumulating large quantities of proline and oxalic acid, which consequently lowers its water potential for uptake of soil water of high salinity. Excess salts were excreted through salt glands. This is an important adaptation for a plant that thrives in a highly variable saline habitat Further investigation of submergence effects on upper intertidal species using B. diffusa showed three key stages in the response. A drop in chlorophyll a+b within 6 hours (4.2 ± 0.2 to 2.4 ± 0.3 mg l-1) with a corresponding increase in carotenoid concentration (0.6 ± 0.1 mg l-1) indicated an immediate response to submergence. Oxalic acid concentration was highest on Day 4 (13.6 mM) as opposed to control levels, indicative of its role in submergence tolerance, thus Day 4 may be the peak of positive acclimation. The third phase was marked by a sharp increase in electrolyte leakage to 47.5 ± 2.6 percent on Day 10, from 9.4 ± 1.4 percent on Day 7, with a corresponding decrease in total dissolved solutes between Days 7 and 10. Results suggest that oxalic acid accumulates under submergence possibly as a stabilizing osmolyte. The threshold for tolerance of the species under submergence is 7 days with membrane damage thereafter. Bassia diffusa would not survive prolonged submergence (> 7 days) but could survive submergence of short duration (< 7 days) through continuous underwater photosynthesis, accumulation of osmolytes such as oxalic acid and carotenoid, and maintenance of relative water content and succulence within control levels. When considered together, results showed that the two upper intertidal species were sensitive to waterlogging and would not survive complete submergence, whereas the lower intertidal species could in addition to its natural range, thrive in conditions typical of the upper intertidal range, namely prolonged dry conditions and high sediment salinity. These results have important implications for the future management of salt marshes under predicted climate change conditions. In permanently open South African estuaries, a landward migration of salt marsh will be possible if coastal squeeze is limited and the rate of landward recruitment is on par with sea level rise. In this case salt marsh species would retain their current zonation while shifting inland. Increased sea storms and saltwater intrusion could lead to high salinity concentration in the sediment and significantly reduce growth of salt-sensitive plants. In estuaries that are temporarily open to the sea, reduced freshwater inflow will result in an increase in mouth closure, high water levels, prolonged submergence, and consequently die back of salt marsh vegetation. On the other hand increased abstraction and drought would result in low water levels and high sediment salinity which would decrease growth and survival of salt marsh. This research has provided new knowledge on the ecophysiology of salt marsh plants which can be used to predict the responses of plants to climate change.
  • Full Text:
  • Date Issued: 2012

The fitting of statistical distributions to wind data in coastal areas of South Africa

  • Authors: Moodley, Kirshnee
  • Date: 2012
  • Subjects: Winds -- South Africa -- Port Elizabeth -- Speed -- Measurement , Wind power -- South Africa -- Port Elizabeth , Winds -- South Africa -- Port Elizabeth -- Measurement -- Mathematical models
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10579
  • Description: Coastal South African cities like Port Elizabeth are said to have a strong potential for wind energy. This study aims to model wind data in order to be able assess the power potential belonging to a given site. The main challenge in modelling wind direction data is that it is categorized as circular data and therefore requires special techniques for handling that are different from usual statistical samples. Statistical tools such as descriptive measures and distribution fitting, were re-invented for directional data by researchers in this field. The von Mises distribution is a predominant distribution in circular statistics and is commonly used to describe wind directions. In this study, the circular principles described by previous researchers were developed by using the statistical software, Mathematica. Graphical methods to present the wind data were developed to give an overview of the behaviour of the winds in any given area. Data collected at Coega, an area near Port Elizabeth, South Africa, was used to illustrate the models which were established in this study. Circular distributions were fit to the directional data in order to make appropriate conclusions about the prevailing wind directions in this area.
  • Full Text:
  • Date Issued: 2012

The further development, optimisation and application of a Yarn Dismantler

  • Authors: Fassihi, Ali Akbar
  • Date: 2012
  • Subjects: Textile industry , Cotton yarn industry
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:10452 , http://hdl.handle.net/10948/d1016066
  • Description: The fibre properties of cotton, which vary widely according to genetic and environmental conditions, determine its price and textile processing performance and product quality. It is therefore hardly surprising that cotton fibre properties are routinely measured for trading and quality control purposes, with a great deal of research having been, and still being, devoted towards developing instruments which enable the various fibre properties to be measured rapidly and accurately. In many cases, it is also necessary to be able to measure properties of cotton fibres when they have already been converted into yarn and fabric form. To do so, the yarn has to be dismantled into its component fibres, preferably without significantly changing the fibre properties. This could only be done by manually untwisting the yarn and carefully extracting the fibres from the untwisted yarn, care being taken not to break or lose any fibres in the process. This is a time consuming, laborious and labour intensive process. In view of this, a „yarn dismantler‟ which could automatically, cost effectively and within acceptable time frames, dismantle a cotton yarn into its constituent fibres, without undue damage or changes to the fibres, was developed and patented. This thesis reports the results of research undertaken to further develop, evaluate and optimize the yarn dismantler into the final prototype, as well as those relating to its practical applications, including tracking changes in fibre properties during miniature and pilot scale processing, up to, and including the yarn stage. Initial research undertaken on the original bench and first prototype models indicated that, although they produced very promising results, certain improvements and modifications were necessary, if the dismantler was to perform in an efficient and operator friendly manner at the required speeds. These included changes in the axial position of the untwisting spindle and the perforated screen of the suction drum, increasing the air suction at the perforated drum, installing a new motor for the untwisting spindle drive, separating the drives to the different parts of the unit in order to control them independently, integrating a more effective steaming unit into the unit etc. It was found that the dismantling rate had to be set to equal about 95 percent of the original twist in the yarn, and that steaming of the dismantled (untwisted) yarn on the perforated drum was necessary in order to eliminate any twist liveliness (residual torque) in the dismantled yarn, and enable it to be handled and tested on the AFIS instrument. When the final prototype Yarn Dismantler was produced, incorporating all the above mentioned improvements, it functioned very well at dismantling speeds of at least 2m/min, enabling the length of yarn required for subsequent AFIS testing to be dismantled within an acceptable time of less than 10 minutes, with excellent reproducibility and repeatability of results, also under commercial conditions. It was found that the AFIS measured length characteristics of fibres from the instrument dismantled yarns compared very well with those of fibres from manually dismantled yarns, differences in fibre length generally being less than 1mm, and it was concluded from these and other evaluation tests, that the yarn dismantler produced fibres without any significant fibre breakage. Some limited tests, carried out on commercially produced carded and combed yarns, indicated that short fibre content and dust and trash levels, as measured by the AFIS on fibres from dismantled yarn, together with the corresponding Uster Statistics, could enable a carded cotton yarn to be distinguished from a combed cotton yarn. Statistical analysis of fibre test results obtained at the different stages during miniature and pilot plant scale processing of various cottons, clearly showed that very significant changes in fibre properties could be caused by certain of the processes. For example, significant fibre breakage occurred during the drafting on the spinning frame, prior to twist insertion. The thesis provides detailed results of changes in various fibre properties, including length, short fibre content, maturity, immature fibre content, seed coat neps and fibrous neps, which occurred from the lint to the final yarn, as well as on the relationship between the properties of the fibres from the dismantled yarn and those from the lint. The results obtained have clearly demonstrated the practical value of the yarn dismantler in enabling yarns to be automatically dismantled into their constituent fibres, which can then be tested by an instrument, such as the AFIS, and the test results related to those of the original lint fibres, thereby opening up many fields of research and practical applications, some of which are captured under „Recommended Further Work‟.
  • Full Text:
  • Date Issued: 2012

The influence of nutrients on surf-zone phytoplankton

  • Authors: Wolmarans, Karien
  • Date: 2012
  • Subjects: Phytoplankton , Algal blooms , Diatoms
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10608 , http://hdl.handle.net/10948/d1008080 , Phytoplankton , Algal blooms , Diatoms
  • Description: The variability in surf-zone phytoplankton community composition together with variability in nutrient concentrations was studied at seven beaches along the coast near Port Elizabeth, South Africa over a one-year sampling period. The nutrient requirements of selected diatoms and dinoflagellates that co-occur at these beaches were studied. The highest nutrient concentrations were recorded at Brighton beach, with phosphate concentration being substantially higher than standards set out for both South African and European waters. Nitrate, ammonium and silicate concentrations were consistent (low variability) at all beaches. The species composition of beaches without surf diatoms was also not variable (except for King’s Beach – an artificial beach). Maitland beach was the only beach that could be identified as a surf diatom beach due to the presence of Anaulus australis. The surf diatom Anaulus australis was found to be a superior competitor compared to all other species tested: the other surf diatom Asterionellopsis glacialis, and the dinoflagellates Gonyaulax spinifera, Prorocentrum micans, and Scrippsiella trochoidea. Gonyaulax spinifera could possibly outcompete Anaulus australis in systems should nitrate become limiting.
  • Full Text:
  • Date Issued: 2012

The molecular analysis of the interation surface between sCD23 and the B2-integrins, CD11b & CD11c

  • Authors: Pereira, Melanie Claire
  • Date: 2012
  • Subjects: CD23 antigen , Immune response -- Regulation
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10337 , http://hdl.handle.net/10948/d1014734
  • Description: Both CD23 and the β2 integrins (also known as CD11/CD18) have very important immunological functions, especially during the allergic response where the binding of CD23 to β2 integrins contributes to various types of signalling in monocytes which can result in drastic sensitivities experienced by some allergic individuals. CD23, also known as the low affinity receptor for immunoglobulin E or (FcεRII), is a type II transmembrane glycoprotein which is synthesized by haematopoietic cells and has biological activity in both membrane-bound and freely soluble forms. It acts via a number of receptors, including the β2 integrins. β2 integrins are specifically found on leukocytes and they play important roles in cell–cell or cell–matrix adhesion via their ability to bind multiple ligands. These molecules occur as heterodimers consisting of an alpha (α) and beta (β) subunit. The α-subunits of β2 integrins contain an approximately 200-amino-acid inserted domain or I-domain which is implicated in ligand binding function. There are four different types of β2 integrins, namely CD11a, CD11b, CD11c and CD11d, all dimers with the common beta subunit, CD18. CD23 and CD11/18 are natural ligands of each other; however the interaction site for CD23 is unknown. It is postulated that the integrin recognizes a tripeptide motif in a small disulfide-bonded loop at the N-terminus of the lectin head region of CD23, which is focussed around Arg172, Lys173 and Cys174 (RKC). This study thus focused on the interaction between the I-domain of CD11 (b and c) and a recombinant 25kDa construct of sCD23. In order to understand the characteristics of ligand binding between the relevant proteins of interest, alanine substitutions on the RKC motif of CD23 were made via site-directed mutagenesis. Consequently, a recombinant form of the I-domain of CD11 (b and c) as well as a wild type (containing the RKC motif) and mutant form (containing an AAC motif) of sCD23 were expressed and purified. The CD11 recombinant proteins were purified via affinity chromatography and the CD23 recombinant proteins via gel filtration chromatography. In addition, synthetic (CD23 derived) peptides, one containing the RKC sequence and the other the AAC sequence, were designed and custom synthesized. The synthetic peptides as well as the recombinant CD23 proteins were then analyzed for their interaction with the CD11 I-domain via ELISA. Subsequent ELISA analyses showed that the native sCD23 and the RKC peptide were able to bind to the integrin α I-domain whereas the mutant sCD23 and the corresponding synthetic AAC peptide failed to bind. This interaction was also analysed via flow cytometry using differentiated U937 cells, yielding similar results. ELISA analyses for the sCD23-CD11b I-domain interaction showed a Kd of 0.36 ± 0.14 μM whereas the RKC-CD11b I-domain interaction yielded a Kd of 1.75 ± 0.58 μM. Similarly, the sCD23-CD11c I-domain interaction yielded a Kd of 0.39 ± 0.09 μM and 1.53 ± 0.72 μM for the RKC-CD11c I-domain interaction. Peptide inhibitory analysis, analysed via ELISA and flow cytometry, reinforced the fact that the RKC motif on sCD23 is a prerequisite for ligand binding of the CD11b/c I-domain.
  • Full Text:
  • Date Issued: 2012

The past and present limnology of the Soetendalsvlei wetlands, Agulhas coast, South Africa

  • Authors: Gordon, Nuette
  • Date: 2012
  • Subjects: Limnology -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:10619 , http://hdl.handle.net/10948/d1009430 , Limnology -- South Africa
  • Description: As climatic conditions continue to change globally, there is a need to assess past environmental change in relation to changing water balance, temperature and sea-level. By understanding the extent of past environmental change, and how anthropogenic impacts have affected ecosystems, better and more accurate future predictions of change can be made. Through the use of the sedimentary record within coastal wetlands, geochemical, (organic content and stable isotopes) and biological (diatoms) proxies were utilised to determine; (i) the baseline water quality record for Soetendalsvlei, one of only a few coastal lakes in South Africa, (ii) the effect of agriculture and mouth manipulation of the Heuningnes Estuary on the microalgae ecology and (iii) the link between palaeo-salinity and trophic status on a regional basis between Soetendalsvlei and Groenvlei, situated 320 km apart. Present water quality and phytoplankton biomass and community structure were assessed for Soetendalsvlei and its associated wetlands, Voëlvlei and Waskraalsvlei to determine the current health of these systems and to obtain modern diatom analogues to be used in the palaeolimnological reconstruction of the coastal lake. Diatoms were not dominant during this study period. Chlorophytes and flagellates were the dominant phytoplankton groups throughout the different wetlands. With the exception of Voëlvlei, the wetlands were all in good health, although SRP concentrations were within the eutrophic to hypertrophic range and are cause for concern. In Voëlvlei, phytoplankton biomass was within the eutrophic range with chlorophyll a concentrations ranging between 20 – 400 ug.l-1 Cyanobacteria, a further indicator of eutrophic conditions, were dominant during the warmer summer periods. Rainfall and freshwater inflow had a significant effect on the biomass and composition of the phytoplankton and acted as a resetting mechanism for all the wetlands as water quality conditions improved thereafter. Comparisons of the water quality and phytoplankton community between the upper reaches of the Heuningnes Estuary and Soetendalsvlei, indicated that artificial breaching of the estuary mouth significantly impacted the connectivity between these two systems, with marine intrusion extending into the upper reaches, while freshwater conditions dominate in the coastal lake. Unfortunately for the palaeolimnological study diatom preservation was poor, however, geochemistry and stable isotope analyses did provide adequate evidence of marine transgression (~8000 yr BP and 4000-2000 yr BP) and regression events comparable to other South African sea-level models developed for the east and west coast. High organic matter content (i.e. higher trophic state) and estuarine POC (C4 vegetation) were associated with periods of marine regression, i.e. increased freshwater, whereas marine transgression events were associated with low organic content and marine POC and DOC. This is comparable to studies conducted in Uruguay (South America) where palaeo-salinity was related to trophic status, i.e. increased freshwater input was associated with high nutrients. Comparisons of the palaeo-record with recorded historical occurrences of droughts and floods, also provided a means of assessing the sedimentary record and to infer anthropogenic impacts after 1850 AD. Overall it can be concluded that coastal lakes of both continents in the Southern Hemisphere displayed similar trophic responses to sea-level fluctuations during the Holocene. This adds valuable information to global sea-level change models.
  • Full Text:
  • Date Issued: 2012

Towards a methodology for identifying potential sites for cemeteries

  • Authors: Judge, Richard David Eadie
  • Date: 2012
  • Subjects: Cemeteries , Environmental impact analysis , Groundwater , Pollution
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10649 , http://hdl.handle.net/10948/d1008048 , Cemeteries , Environmental impact analysis , Groundwater , Pollution
  • Description: Due to death being an extremely sensitive issue, the topic of cemeteries and associated environmental impacts is often left outside the mainstream environmental critique. However, this is a topic becoming more prevalent as the population numbers and the death rate increases, while the amount of available land decreases. Recent research has indicated that poorly sited cemeteries may pose a significant threat to groundwater resources with the consequential potential for severe health hazards. This has resulted in the need for a method of determining the acceptability of a given area for the establishment of a cemetery in a South African context. Cemeteries should be sited in such a way as to mitigate potential public health and safety concerns, minimise associated environmental impacts and provide a method of body disposal that is economically viable. This study therefore provides an integrated methodology to identify and assess a given area and rank a number of potential sites, ultimately determining a single cemetery site which proves to be acceptable for the establishment of a cemetery. Cemetery site selection should be based on the factors affecting the pollution potential of a proposed cemetery. These factors were identified and quantified based on research into the mechanisms of cemetery site pollution resulting in a number of fatal flaws and criteria deemed decisive when selecting a potential cemetery site. The assessment of a site with regards to these criteria and fatal flaws is undertaken through the use of GIS analysis software utilising data layers containing information on the site selection criteria, by investigating existing studies, literature or reports relating to the relevant area, or through field investigations. Although these criteria are vital when determining the specific characteristics of a site in terms of its pollution potential, a method of assessing a number of potential sites with regards to these criteria is vital. To this end, a multi-criteria ranking matrix has been developed, allowing for an objective method of assessing individual sites and thus indicating which sites are more suited for the establishment of a cemetery. The ranking matrix identifies a range of values for each criterion, therefore identifying a minimum and maximum allowable value. A site is then assessed with regards to these criteria in relation to the values identified in the ranking matrix. Each criteria is assigned a score according to the site conditions. Once the criteria for each site has been assessed and scored, the results can be tallied allowing the sites to be ranked according to which site proved to be the most acceptable for a cemetery based on the findings of the application of the site selection criteria. The methodology developed in this study is unique to previous studies in that it provides an integrated and staged approach to identifying, assessing and applying the criteria affecting the pollution potential of a cemetery. The methodology also provides a means of ranking a number of potential sites so to determine the most suitable. Furthermore, the criteria deemed as decisive in previous investigations were in most cases not quantified by the relevant authors, therefore leaving many of the criteria values up for interpretation. For this methodology to be affective, all criteria must be quantified therefore identifying maximum and minimum allowable limits for each. This study applies minimum and maximum allowable limits to these criteria, therefore aiding in the ranking process. The integrated methodology developed was then applied to a case study where by the effectiveness in identifying a number of potential cemetery sites could be tested. Subsequent to the application of this methodology to a case study, it was concluded that an additional two criteria, not identified in previous investigations, needed to be assessed to more adequately determine the suitability or otherwise of a site for a cemetery. Ultimately, twelve major criteria have been proposed for use as the basis of the methodology. The methodology and pertinent criteria proposed in this study should be compiled as a standard for planning authorities and consultants to use as a method of determining a number of potential environmentally sound cemetery sites.
  • Full Text:
  • Date Issued: 2012

Towards integrated catchment management : challenges surrounding implementation in the Gamtoos River catchment

  • Authors: Materechera, Fenji
  • Date: 2012
  • Subjects: Watershed management -- South Africa , Watershed management -- South Africa -- Citizen participation , Integrated water development -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10664 , http://hdl.handle.net/10948/d1018553
  • Description: Water resource management has become a pertinent issue of global environmental concern in response to the conditions of a growing global population, increasing development and a limited freshwater supply. It is against the backdrop of such conditions that effective water resource management has gained popularity in seeking to ensure that the needs of the growing population will be met and secured for future generations. The notion of integrated water resource management (IWRM) is a perspective on water resource management that has evolved out of the global opinion that social and ecological systems are linked and therefore cannot be managed separately. The department of water affairs (DWA) in South Africa highlights the importance of approaching management of water resources from a catchment perspective which forms the basis for a particular integrated approach to management called integrated catchment management (ICM). ICM recognizes the catchment as the correct administrative unit for management. It integrates water resources and the land that forms the catchment area in planning and management. Researchers have described the implementation of ICM as being complicated and difficult. This is no exception to South Africa. Principles of ICM have received widespread prominence in South Africa as they have been incorporated into national water policy. Actual implementation however is still in its infancy. The study is therefore a case study of ICM with respect to factors influencing implementation amongst different stakeholders. The study aims to explore the theme of implementation of ICM within the context of the Gamtoos River Catchment with a view toward identifying and addressing challenges that may be more broadly applicable. The study adopts an inductive, exploratory approach to the connection between theory and practice. A systems-based framework characterized by sequential steps similar to that employed in a case study conducted by Bellamy et al. (2001) in Queensland Australia is used to facilitate the evaluation of ICM in the Gamtoos River Catchment. The evaluation is achieved through a three step process of exploration in the current study. Triangulation is applied to the choice of methods of analysis which involves the use of a global analysis method, the use of learning scenarios and a grounded theory method. Findings reveal seven core themes which help to provide a detailed, contextual understanding relating to the status quo for ICM in the catchment. Results from a grounded theory analysis summarized the main challenges to implementation into five broad categories. Based on this analysis method and the application of the three learning scenarios for the Gamtoos River Catchment, the extent to which these challenges exist was discovered. The state of ICM in the catchment was classified as falling within a condition of a level of success being achieved with room for improvement to a condition of optimal ICM. The study concludes that based on the context of ICM being an example of a Complex Adaptive Systems (CAS), this state of ICM in the Gamtoos River Catchment is subject to change. This therefore necessitates the consideration of approaches to implementation that are adaptive to change. Findings may serve to inform decision making on how ICM can be effectively implemented elsewhere in a South African context.
  • Full Text:
  • Date Issued: 2012

Using an intelligent self-service solution to support telecommunication service provisioning

  • Authors: Barlow, Sherwin Riaan
  • Date: 2012
  • Subjects: Telecommunication systems -- Management , Electronic commerce -- Computer programs , Web applications
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10484 , http://hdl.handle.net/10948/d1013417
  • Description: The increasing competition between telecommunication service providers (TSPs) and the large amounts of human resource costs incurred to provision telecommunication services to small, medium and micro enterprises (SMMEs), highlight the need for effective self-service provisioning methods to reduce costs. Existing service provisioning methods do not effectively support SMMEs in the service provisioning process. The current methods used are manual and Web-based. The manual service provisioning method is labour and time-intensive. TSPs are being forced to cut human resource costs as the profit margins for provisioning services are narrow due to competition. The current web-based systems do not allow SMMEs to effectively purchase services as they provide long textual lists to consult and limited information about services. The objective of this research was to develop an intelligent web-based self-service system to support SMMEs in telecommunication service provisioning, using a Design Science Research methodology. A constraint-based, knowledge-based recommender system was selected as the most appropriate intelligent system to support telecommunication service provisioning. A prototype called SelPro was developed as a solution to address the shortcomings of the current ineffective service provisioning methods available for SMMEs. SelPro incorporates an interactive wizard-style user interface with dynamic recommendations to support novice users as well as an expert interface which provides less user support. An expert review and a user study were conducted to determine if SelPro was usable, useful and effective. SelPro was perceived as being usable for SMMEs wishing to purchase telecommunication services. Expert participants were satisfied with the usability of SelPro and perceived it as being useful, easy to use and easy to learn. SelPro was considered effective because of the high task success ratings provided by the participants using the two interfaces. The research determined that intelligent web-based self-service provisioning can be used to effectively support SMMEs in telecommunication service provisioning. General design recommendations for similar systems were proposed and future work will involve using intelligent systems to support large enterprises in telecommunication service provisioning.
  • Full Text:
  • Date Issued: 2012

Using mobile information visualisation to support the analysis of telecommunication service ultilisation

  • Authors: Twigg, Gianni Gurshwin
  • Date: 2012
  • Subjects: Telecommunication , Visualization , Technology -- Social aspects
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10497 , http://hdl.handle.net/10948/d1020831
  • Description: Telecommunication service utilisation (TSU) focuses on how customers make use of telecommunication services and can provide valuable information for decision making for improved customer service delivery. When a telecommunication service provider consults with customers, large amounts of static documentation on TSU data are compiled. Compiling this documentation for in-field investigation is manually intensive and the documentation does not effectively support decision making. Existing systems for visualising TSU data do not efficiently support in-field investigation of TSU and lack dynamic interaction. This highlights the need to investigate a solution to better support in-field investigation of TSU. This research followed a Design Science Research methodology to develop and evaluate a solution to solve the problem identified. The use of tablet devices for in-field investigation of TSU was identified as a suitable solution. Mobile information visualisation (MIV) techniques were investigated to determine appropriate display and interaction techniques for the visualisation of TSU data on a tablet device. An existing visualisation framework for TSU was identified and extended to incorporate touch-based interactions. Three service usage views were identified for visualising TSU, namely a Trend, Network and Detail Usage View. A Dashboard View was also identified to provide a quick reference view of the different views. A prototype called MobiTel was developed on a tablet device. MobiTel incorporated the identified information visualisation techniques. MobiTel was evaluated using an expert review and a user study to determine its usability and usefulness. The results indicated that MobiTel was perceived as being useful for in-field investigation and that the participants perceived the prototype to be easy to use and learn. The user study also indicated that the participants were satisfied with MobiTel. This research has determined that MIV techniques can be used for in-field investigation of TSU. Design recommendations were devised for designing an interactive mobile prototype for visualising service usage information. Future work will involve using map-based visualisation for visualising TSU data on different customer sites.
  • Full Text:
  • Date Issued: 2012

Vapour phase dehydrogenation of cyclohexane on microstructured reactors

  • Authors: Mpuhlu, Batsho
  • Date: 2012
  • Subjects: Dehydrogenation , Cyclohexane
  • Language: English
  • Type: Thesis , Doctoral , DTech (Chemistry)
  • Identifier: http://hdl.handle.net/10948/8661 , vital:26418
  • Description: The work that is described in this thesis forms part of the research and development projects at InnoVenton: NMMU Institute of Chemical Technology in collaboration with Sasol Technologies. The broader view of the project was testing on the so-called “Small Production Platforms” (SPP’s). In particular the main aim of this study was to investigate the effect of micro-structuring on the heterogeneous catalysed, vapour-phase oxidative dehydrogenation of cyclohexane in the presence of air. Ground work studies were done to provide a proper comparison of the micro-structured reactor with a traditional fixed-bed reactor. These included evaluation of a proper vanadium pyrophosphate catalyst for the reaction, testing of reaction parameters for the oxidative dehydrogenation reaction on a fixed-bed reactor and lastly comparing the performance of the micro-structured reactor to that of the fixed-bed reactor Various vanadium pyrophosphate catalysts that were tested for activity included: bulk (VO)2P2O7, bulk (VO)2P2O7 promoted with Fe, (VO)2P2O7 supported on -Al2O3 and Fe promoted (VO)2P2O7 supported on -Al2O3. These catalysts showed significant differences in TOF, however it was not conclusive from the results whether these differences may be traced to increased activity for dehydrogenation for different catalysts since all reactions were run under conditions of oxygen deficiency. It is, however, clear that Fe promotion significantly increase activity, irrespective of the relative degrees of oxidative dehydrogenation and normal dehydrogenation. The Fe promoted catalyst was further tested for long term stability in-view of using it as the catalyst in the micro-structured reactor. These studies showed the catalyst to have a high degree of stability with minimal structural changes under the reaction conditions used. Various response surface models describing the variation in each of the cyclohexane conversion, cyclohexene selectivity, and benzene selectivity, respectively when changing reaction condition, were derived by means of multiple regression. To obtain some idea of the degree and nature of the normal dehydrogenation reaction, the amount of deficit oxygen was estimated from the measured results for cyclohexane conversion and cyclohexene and benzene selectivities. These estimated values were also modelled as described above. The regression models were used to interpret specific trends in the responses for the oxidative dehydrogenation of cyclohexane and account for the oxygen deficit in the system. The performance of a fixed bed tubular reactor (FBR) and micro-structured sandwich reactor (MSSR) were compared over an Fe promoted vanadium pyrophosphate. Reactor performance was evaluated by varying specific reaction conditions (temperature and space velocity). Subsequently the turn-over frequencies, conversion and selectivities from the two reactors were compared. The conversion achieved in the micro-structured reactor was observed to be significantly higher than that achieved in the fixed-bed reactor at all reaction parameters. This is despite the fact that the total amount of catalyst in the micro-structured reactor is approximately 5 times less than that used in the fixed bed reactor. In addition, the contact time (1/MHSV) in the micro-structured reactor is also significantly shorter than in the fixed-bed reactor.
  • Full Text:
  • Date Issued: 2012

A comprehensive evaluation framework for system modernization : a case study using data services

  • Authors: Barnes, Meredith Anne
  • Date: 2011
  • Subjects: Computer architecture
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10460 , http://hdl.handle.net/10948/1499 , Computer architecture
  • Description: Modernization is a solution to migrate cumbersome existing systems to a new architecture for improved longevity of business processes. Three modernization approaches exist. White-box and black-box modernization are distinct from one another. Grey-box modernization is a hybrid of the white-box and black-box approaches. Modernization can be utilised to create data services for a Service Oriented Architecture. Since it is unclear which modernization approach is more suitable for the development of data services, a comprehensive evaluation framework is proposed to evaluate which of the white- or black-box approaches is more suitable. The comprehensive framework consists of three evaluation components. Firstly, developer effort to modernize existing code is measured by acknowledged software metrics. Secondly, the quality of the data services is measured against identified Quality of Service criteria for data services in particular. Thirdly, the effectiveness of the modernized data services is measured through usability evaluations. By inspection of the combination of application of each of the evaluation components, a recommended approach is identified for the modernization of data services. The comprehensive framework was successfully employed to compare the white-box and black-box modernization approaches applied to a case study. Results indicated that had only a single evaluation component been used, inconclusive results of the more suitable approach may have been obtained. The findings of this research contribute a comprehensive evaluation framework which can be applied to compare modernization approaches and measure modernization success.
  • Full Text:
  • Date Issued: 2011

A forecasting model for photovoltaic module energy production

  • Authors: Swanepoel, Paul
  • Date: 2011
  • Subjects: Photovoltaic power systems -- Forecasting
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: vital:10563 , http://hdl.handle.net/10948/1420 , Photovoltaic power systems -- Forecasting
  • Description: Energy is of concern for governments and economies all over the world. As conventional methods of energy production are facing the prospect of depleting fossil fuel reserves, economies are facing energy risks. With this tension, various threats arise in terms of energy supply security. A shift from intensive fossil fuel consumption to alternative energy consumption combined with the calculated use of fossil fuels needs to be implemented. Using the energy radiated from the sun and converted to electricity through photovoltaic energy conversion is one of the alternative and renewable sources to address the limited fossil fuel dilemma. South Africa receives an abundance of sunlight irradiance, but limited knowledge of the implementation and possible energy yield of photovoltaic energy production in South Africa is available. Photovoltaic energy yield knowledge is vital in applications for farms, rural areas and remote transmitting devices where the construction of electricity grids are not cost effective. In this study various meteorological and energy parameters about photovoltaics were captured in Port Elizabeth (South Africa) and analyzed, with data being recorded every few seconds. A model for mean daily photovoltaic power output was developed and the relationships between the independent variables analyzed. A model was developed that can forecast mean daily photovoltaic power output using only temperature derived variables and time. The mean daily photovoltaic power model can then easily be used to forecast daily photovoltaic energy output using the number of sunlight seconds in a given day.
  • Full Text:
  • Date Issued: 2011

A framework for the adoption of enterprise resource planning (ERP) systems in higher education

  • Authors: Scholtz, Brenda
  • Date: 2011
  • Subjects: Curriculum change , Enterprise resource planning.
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:10485 , http://hdl.handle.net/10948/d1015961
  • Description: Information Communication Technology (ICT) practitioners and Enterprise Resource Planning (ERP) specialists are highly sought after globally and in South Africa. In order to address this need for ERP specialists, several studies propose that ERP systems should be adopted in the Information Systems (IS) curricula in higher education institutions (HEIs) for instructional purposes. Whilst many HEIs in the United States, Australia and Europe have successfully adopted ERP systems into their curricula, less than 30% of South African HEIs have followed this trend. The adoption of ERP systems is a challenging process as such systems are resource-intensive, costly, complex, and have a steep learning curve. Educators are faced with resource problems and a dearth of options relating to the adoption process. In addition it is critical that the skills and knowledge competencies attained in these courses are industry-relevant. Several education frameworks have been recommended to assist educators with the process of adopting an ERP system in the curriculum, but these frameworks are not comprehensive since they do not consider all the factors relating to the adoption of an ERP system. In addition existing frameworks are not based on industry-relevant competencies but rather on educational objectives. This has resulted in a difference between the competencies required by organisations and those produced by higher education. Whilst there are several research studies on ERP education, empirical studies on frameworks supporting the adoption of ERP systems in HEIs for instructional purposes are limited, particularly on the impact of these frameworks on educational outcomes. The impact of the usability of the ERP system on educational outcomes has also not been fully explored. A survey of ERP consulting organisations in South Africa confirmed that these organisations struggle to obtain ERP specialists with the appropriate competencies. The survey results also contributed to a standardised, comprehensive, set of industry-relevant ERP competencies. The competency set forms part of a comprehensive Competency Framework for ERP System Adoption in IS Higher Education (ERPEd), which can assist educators with the decisions relating to the adoption of an ERP system into the IS curriculum. It includes all the categories of competencies relevant to industry and maps these onto a recommended ERP system adoption approach, an ERP learning tool, as well as the appropriate level of adoption. The application of the ERPEd framework to a case study, the Management Information Systems (MIS) course at the Nelson Mandela Metropolitan University (NMMU), resulted in the adoption of the SYSPRO medium-sized ERP system into the MIS course with the hands-on approach. The empirical results of the evaluation of the case study revealed that the hands-on use of a medium-sized ERP system, SYSPRO, can successfully contribute to the attainment of educational outcomes. These outcomes were mapped to the three core competencies addressed by the MIS course, which were ERP Theory and Concepts, ERP Transactions and Business Process Management (BPM). The educational outcomes evaluated were the measures of performance, self-efficacy and usability. Self-efficacy included satisfaction with the adoption approach. The results were positive in terms of all the metrics of performance, and all three competency categories had positive post-intervention self-efficacy ratings. In terms of growth in self-efficacy from pre-intervention to post-intervention, BPM was the only competency category that did not show a significant growth, however the satisfaction data indicated that students found that the use of SYSPRO improved their competencies in business process understanding. Usability was evaluated in terms of navigation, presentation and learnability. Learnability was the only usability measure in the neutral range, with the other measures falling in the positive range. This confirms related studies reporting that ERP systems are not designed for learning. Overall the students enjoyed the practical application of the theory by using SYSPRO. Several positive and negative features of the user interface were provided which can be used in the design of improved ERP systems for instructional purposes. The results of this investigation can assist in narrowing the gap between industry requirements and IS education programmes. The ERP competency set provides a standardised list of skills and knowledge which is the starting point for any skills improvement program. The ERPEd framework can improve the quality of ERP courses and the competencies of IS graduates. This in turn, can benefit the business community since it will improve the chances of ERP project success. This research is a major contribution to both government and academic initiatives in South Africa to address both the ICT skills problem as well as the need for ERP specialists.
  • Full Text:
  • Date Issued: 2011

A status assessment of mangrove forests in South Africa and the utilization of mangroves at Mngazana Estuary

  • Authors: Rajkaran, Anusha
  • Date: 2011
  • Subjects: Mangrove forests -- Management , Forests and forestry -- Harvesting , Mangrove forests -- South Africa -- Mngazana Estuary , Mangrove ecology -- South Africa -- Mngazana Estuary , Mangrove conservation
  • Language: English
  • Type: Thesis , Doctoral , DPhil
  • Identifier: vital:10604 , http://hdl.handle.net/10948/1547 , Mangrove forests -- Management , Forests and forestry -- Harvesting , Mangrove forests -- South Africa -- Mngazana Estuary , Mangrove ecology -- South Africa -- Mngazana Estuary , Mangrove conservation
  • Description: In South Africa mangrove forests are located in estuaries from Kosi Bay in KwaZulu-Natal (KZN) to Nahoon Estuary in the Eastern Cape. The aims of this study were to determine the present state of mangroves in KwaZulu-Natal, by assessing the current population structure, the changes in cover over time and associated anthropogenic pressures. A second objective of this study was to determine the effect of harvesting on the population structure and sediment characteristics in the Mngazana mangrove forest. To determine if harvesting was sustainable at Mngazana Estuary; the growth and mortality rates and associated growth conditions were measured. Finally by using population modelling sustainable harvesting limits were determined by predicting the change in population structure over time. The study focussed on the KwaZulu-Natal province as a fairly recent study addressed mangrove distribution and status in the Eastern Cape Province. A historical assessment of all mangroves forests in KwaZulu-Natal (KZN) revealed that the potential threats to mangroves in South Africa include; wood harvesting, altered water flow patterns coupled with salinity changes, prolonged closed-mouth conditions and subsequent changes to the intertidal habitat. As a result mangroves were completely lost from eleven estuaries in KZN between 1982 and 1999 and a further two estuaries by 2006. Mangroves only occurred in those estuaries where the mouth was open for more than 56 percent of the time with the exception of St Lucia, where the mouth has been closed for longer but the mangrove communities have persisted because the roots of the trees were not submerged. All mangrove forests in KZN were regenerating in terms of population structure as they had reverse J-shaped population curves as well as high adult: seedling ratios. Kosi Bay and Mhlathuze Estuary were two of the larger forests that showed signs of harvesting (presence of tree or branch stumps), but the greatest threat to smaller estuaries seems to be altered water flow patterns due to freshwater abstraction in the catchments and the change of land use from natural vegetation to sugar-cane plantations. These threats affect the hydrology of estuaries and the sediment characteristics (particle size, redox, pH, salinity, temperature) of the mangrove forests. The environmental conditions under which the mangrove forests currently exist were determined for five species. Lumnitzera racemosa and Ceriops tagal exhibited a narrow range of conditions as these species are only found at Kosi Bay, while Avicennia marina, Bruguiera gymnorrhiza and Rhizophora mucronata were found to exist under a wider range of conditions. The growth rate and response to environmental conditions of the three dominant species were important to determine as these species are impacted by harvesting. Mangrove growth rates were measured at Mngazana Estuary in the Eastern Cape, the third largest mangrove forest in South Africa. Areas of this estuary where mangroves harvesting has occurred, show significant differences in sediment characteristics as well as changes in population structure in harvested compared to non harvested sites. The growth rate (in terms of height) of Avicennia marina individuals increased from seedlings (0.31 cm month-1) to adults (1.2 cm month-1), while the growth of Bruguiera gymnorrhiza stabilised from a height of 150 cm at 0.65 cm month-1. The growth of Rhizophora mucronata peaked at 0.72 cm month-1 (height 151-250 cm) and then decreased to 0.4 cm month-1 for taller individuals. Increases in diameter at breast height (DBH) ranged between 0.7 and 2.3 mm month-1 for all species. Some environmental variables were found to be important drivers of growth and mortality of individuals less then 150 cm. A decrease in sediment pH significantly increased the mortality of Avicennia marina seedlings (0-50 cm) (r = - 0.71, p<0.05) and significantly decreased the growth of Rhizophora mucronata and Bruguiera gymnorrhiza seedlings (r = -0.8, r = 0.52 – p < 0.05 respectively). At Mngazana Estuary, mortality of this species showed a positive correlation with sediment moisture content indicating that this species prefers drier conditions. The density of Rhizophora mucronata was significantly correlated to porewater temperature in Northern KZN as was the growth of adult (>300 cm) Rhizophora trees at Mngazana Estuary. Mortality of Avicennia marina individuals (51-150 cm) was related to tree density indicating intraspecific competition and self thinning. Selective harvesting of particular size classes of Rhizophora mucronata was recorded when comparing length of harvested poles (~301 cm) and the size class distribution of individuals. Taking into account the differences in growth rate for each size class for this species it will take approximately 13 years to attain a height of 390 cm which is the height at which trees are selected for harvesting at this estuary. This is 2.6 times slower than those individuals growing in Kenya. The feasibility of harvesting is dependent on the growth rate of younger size classes to replace harvested trees as well as the rate of natural recruitment feeding into the population. Different harvesting intensity scenarios tested within a matrix model framework showed that limits should be set at 5 percent trees ha-1 year-1 to maintain seedling density at > 5 000 ha-1 for R. mucronata. However harvesting of Bruguiera gymnorrhiza should be stopped due to the low density of this species at Mngazana Estuary. Harvesting of the tallest trees of Avicennia marina can be maintained at levels less than 10 percent ha-1 year-1. Effective management of mangrove forests in South African is important to maintain the current state, function and diversity of these ecosystems. Management recommendations should begin with determining the freshwater requirements of the estuaries to maintain the mouth dynamics and biotic communities and deter the harvesting of (whole) adult trees particularly those species that do not coppice. Further management is needed to ensure that forests are cleared of pollutants (plastic and industrial), and any further developments near the mangroves should be minimized.
  • Full Text:
  • Date Issued: 2011

An evaluation of UPLC technology for the simultaneous analysis of actives in a multi-active drug

  • Authors: Bawjee, Janita
  • Date: 2011
  • Subjects: High performance liquid chromatography
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: vital:10384 , http://hdl.handle.net/10948/d1008407 , High performance liquid chromatography
  • Description: The evaluation of the potential to use Ultra Performance Liquid Chromatography (UPLC) for the simultaneous quantification of all the actives in a multi-active tablet is described in this work. Part of the evaluation was to ensure that the necessary regulatory requirements were adhered to by ascertaining that an analytical method is suitable for a specific purpose through analytical method validation for the specific multi-active tablet. The UPLC method was also tested for the analysis of similar products, namely tablet formulations that contain similar active ingredients in the same proportions but with an additional active ingredient. A method for the simultaneous determination of paracetamol, caffeine and codeine phosphate was developed using UPLC technology. The UPLC developed method was more efficient than the existing in-house HPLC method. The UPLC method was then validated in accordance to ICH and USP guidelines. The application of this UPLC method for the analysis of similar products containing paracetamol, caffeine, codeine phosphate and one extra active ingredient was very challenging. The low concentration of the additional component, differences in sample matrix and differences in formulations added to the challenges. The direct application for the analysis of products Y and Z was not successful; however the method could be used as a platform for further research. A cost comparison between the UPLC and HPLC methods showed the UPLC method to be more cost effective. Thus, while maintenance costs are higher for the UPLC instrument, column costs are comparable to HPLC columns, but solvent and waste disposal charges decrease considerably due to lower solvent use. The reduction in instrument time dramatically improves the cost effectiveness of UPLC over HPLC due to a concurrent reduction in analyst time requirement. The results of this study show that the analytical costs associated with the analysis of multi-active drugs using HPLC procedures can be reduced substantially by the CONFIDENTIAL INTELLECTUAL PROPERTY OF ASPEN PHARMACARE implementation of UPLC technology. The hypothesis that the enhanced chromatographic power of UPLC can be leveraged to provide faster analysis times hence increased product throughput rates, and lower operating costs for the analysis of multi-active drugs was accepted. These advantages were achieved whilst meeting all regulatory requirements for analytical methods as required by regulatory bodies.
  • Full Text:
  • Date Issued: 2011

An intelligent multimodal interface for in-car communication systems

  • Authors: Sielinou, Patrick Tchankue
  • Date: 2011
  • Subjects: Automotive telematics , Automobiles -- Electronic equipment
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10461 , http://hdl.handle.net/10948/1495 , Automotive telematics , Automobiles -- Electronic equipment
  • Description: In-car communication systems (ICCS) are becoming more frequently used by drivers. ICCS are used in order to minimise the driving distraction due to using a mobile phone while driving. Several usability studies of ICCS utilising speech user interfaces (SUIs) have identified usability issues that can affect the workload, performance, satisfaction and user experience of the driver. This is due to current speech technologies which can be a source of errors that may frustrate the driver and negatively affect the user experience. The aim of this research was to design a new multimodal interface that will manage the interaction between an ICCS and the driver. Unlike the current ICCS, it should make more voice input available, so as to support tasks (e.g. sending text messages; browsing the phone book, etc), which still require a cognitive workload from the driver. An adaptive multimodal interface was proposed in order to address current ICCS issues. The multimodal interface used both speech and manual input; however only the speech channel is used as output. This was done in order to minimise the visual distraction that graphical user interfaces or haptics devices can cause with current ICCS. The adaptive interface was designed to minimise the cognitive distraction of the driver. The adaptive interface ensures that whenever the distraction level of the driver is high, any information communication is postponed. After the design and the implementation of the first version of the prototype interface, called MIMI, a usability evaluation was conducted in order to identify any possible usability issues. Although voice dialling was found to be problematic, the results were encouraging in terms of performance, workload and user satisfaction. The suggestions received from the participants to improve the system usability were incorporated in the next implementation of MIMI. The adaptive module was then implemented to reduce driver distraction based on the driver‟s current context. The proposed architecture showed encouraging results in terms of usability and safety. The adaptive behaviour of MIMI significantly contributed to the reduction of cognitive distraction, because drivers received less information during difficult driving situations.
  • Full Text:
  • Date Issued: 2011

An investigation into the effect of carbon type addictives on the negative electrode during the partial state of charge capacity cycling of lead acid batteries

  • Authors: Snyders, Charmelle
  • Date: 2011
  • Subjects: Lead-acid batteries
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10379 , http://hdl.handle.net/10948/1494 , Lead-acid batteries
  • Description: It is well known that a conventional lead acid cell that is exposed to a partial state of charge capacity cycling (PSoCCC) would experience a build-up of irreversible PbSO4 on the negative electrode. This results into a damaged negative electrode due to excessive PbSO4 formation by the typical visual “Venetian Blinds” effect of the active material. This displays the loss of adhesion of the active material with the electrode’s grids thereby making large sections of the material ineffective and reducing the cells useful capacity during high current applications. The addition of certain graphites to the negative paste mix had proven to be successful to reduce this effect. In the first part of the study, the physical and chemical properties of the various additives that are added to the negative electrode paste mix were comparatively studied. This was done to investigate any significant differences between various suppliers that could possibly influence the electrochemical characteristics of the Pb-acid battery performance. This comparative study was done by using the following analytical techniques; BET surface area, laser diffraction particle size, PXRD, TGA-MS and SEM. The study showed that there were no significant differences between the additives supplied from different suppliers except for some anomalies in the usefulness of techniques such as N2 adsorption to study the BET surface area of BaSO4. In order to reduce the sulphation effect from occurring within the Pb-acid battery a number of adjustments are made to the electrode active material. For example, Pb-acid battery manufacturers make use of an inert polymer based material, known as Polymat, to cover the electrode surfaces as part of their continuous electrode pasting process. It is made from a non woven polyester fiber that is applied to the pasted electrodes during the continuous pasting process. In this study the Polymat pasted electrodes has demonstrated a better physical adhesion of the active material to the grid support thereby maintaining the active material’s physical integrity. This however did not reduce the sulphation effect due to the high rate partial state of capacity cycling (HRPSoCCC) test but reduced the physical damage due to the irreversible active material blistering effect. The study investigated what effect the Polymat on the electrodes has on the III battery’s Cold Cranking Ability (CCA) at -18 degree C, the HRPSoCCC cycling and its active material utilization. The study showed that there was little or no differences in the CCA and HRPSoCCC capabilities of cells made with the Polymat when compared to cells without the Polymat, with significant improvement in active material’s adhesion and integrity to the grid wire. This was confirmed by PXRD and SEM analysis. Negative electrodes were made with four types of graphites (natural, flake, expanded and nano fibre) added to the negative paste mixture in order to reduce the effect of sulphation. The study looked at using statistical design of experiment (DoE) principles to investigate the variables (additives) such as different graphites, BaSO4 and Vanisperse to the negative electrode paste mixture where upon measuring the responses (electrochemical tests) a set of controlled experiments were done to study the extent of the variables interaction, dependency and independency on the cells electrochemical properties. This was especially in relation to the improvement of the battery’s ability to work under HRPSoCCC. The statistical analysis showed that there was a notable significant influence of the amounts of vanisperse, BaSO4 and their respective interactions on a number of electrochemical responses, such as the Peukert constant (n), CCA discharge time, material utilization at different discharge rates and the ability to capacity cycle under the simulated HRPSoCCC testing. The study did not suggest an optimized concentration of the additives, but did give an indication that there was a statistical significant trend in certain electrochemical responses with an interaction between the amounts of the additives BaSO4 and Vanisperse. The study also showed that the addition of a small amount of Nano carbon can significantly change the observed crystal morphology of the negative active material and that an improvement in the number of capacity cycles can be achieved during the HRPSoCCC test when compared to the other types of graphite additives.
  • Full Text:
  • Date Issued: 2011
  • Disclaimer
  • Privacy
  • Copyright
  • Contact