Showing items 21 - 40 of 1271

Your selections:

A 150 MHz all sky survey with the Precision Array to Probe the Epoch of Reionization

  • Authors: Chege, James Kariuki
  • Date: 2020
  • Subjects: Epoch of reionization -- Research , Astronomy -- Observations , Radio interferometers
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/117733 , vital:34556
  • Description: The Precision Array to Probe the Epoch of Reionization (PAPER) was built to measure the redshifted 21 cm line of hydrogen from cosmic reionization. Such low frequency observations promise to be the best means of understanding the cosmic dawn; when the first galaxies in the universe formed, and also the Epoch of Reionization; when the intergalactic medium changed from neutral to ionized. The major challenges to these observations is the presence of astrophysical foregrounds that are much brighter than the cosmological signal. Here, I present an all-sky survey at 150 MHz obtained from the analysis of 300 hours of PAPER observations. Particular focus is given to the calibration and imaging techniques that need to deal with the wide field of view of a non-tracking instrument. The survey covers ~ 7000 square degrees of the southern sky. From a sky area of 4400 square degrees out of the total survey area, I extract a catalogue of sources brighter than 4 Jy whose accuracy was tested against the published GLEAM catalogue, leading to a fractional difference rms better than 20%. The catalogue provides an all-sky accurate model of the extragalactic foreground to be used for the calibration of future Epoch of Reionization observations and to be subtracted from the PAPER observations themselves in order to mitigate the foreground contamination.
  • Full Text:
  • Date Issued: 2020

A Bayesian approach to tilted-ring modelling of galaxies

  • Authors: Maina, Eric Kamau
  • Date: 2020
  • Subjects: Bayesian statistical decision theory , Galaxies , Radio astronomy , TiRiFiC (Tilted Ring Fitting Code) , Neutral hydrogen , Spectroscopic data cubes , Galaxy parametrisation
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/145783 , vital:38466
  • Description: The orbits of neutral hydrogen (H I) gas found in most disk galaxies are circular and also exhibit long-lived warps at large radii where the restoring gravitational forces of the inner disk become weak (Spekkens and Giovanelli 2006). These warps make the tilted-ring model an ideal choice for galaxy parametrisation. Analysis software utilizing the tilted-ring-model can be grouped into two and three-dimensional based software. Józsa et al. (2007b) demonstrated that three dimensional based software is better suited for galaxy parametrisation because it is affected by the effect of beam smearing only by increasing the uncertainty of parameters but not with the notorious systematic effects observed for two-dimensional fitting techniques. TiRiFiC, The Tilted Ring Fitting Code (Józsa et al. 2007b), is a software to construct parameterised models of high-resolution data cubes of rotating galaxies. It uses the tilted-ring model, and with that, a combination of some parameters such as surface brightness, position angle, rotation velocity and inclination, to describe galaxies. TiRiFiC works by directly fitting tilted-ring models to spectroscopic data cubes and hence is not affected by beam smearing or line-of-site-effects, e.g. strong warps. Because of that, the method is unavoidable as an analytic method in future Hi surveys. In the current implementation, though, there are several drawbacks. The implemented optimisers search for local solutions in parameter space only, do not quantify correlations between parameters and cannot find errors of single parameters. In theory, these drawbacks can be overcome by using Bayesian statistics, implemented in Multinest (Feroz et al. 2008), as it allows for sampling a posterior distribution irrespective of its multimodal nature resulting in parameter samples that correspond to the maximum in the posterior distribution. These parameter samples can be used as well to quantify correlations and find errors of single parameters. Since this method employs Bayesian statistics, it also allows the user to leverage any prior information they may have on parameter values.
  • Full Text:
  • Date Issued: 2020

A best practice guideline for screening and managing chorioamnionitis

  • Authors: Du Plessis, Allison Herlene
  • Date: 2020
  • Subjects: Bacterial diseases
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/46374 , vital:39575
  • Description: Due to the complex nature of chorioamnionitis, women are often misdiagnosed, undiagnosed or only diagnosed after birth when it is too late to prevent maternal and neonatal complications. A lack of a comprehensive best practice guidelinefor screening and managing women withchorioamnionitis resultsin delayed treatment and management that could minimise maternal and neonatal complications. Saving Babiesreported that unexplained intra-uterine deathsremained the main primary (obstetric) cause of death for babies with a weight above 1000g (24.4%of all deaths). Of these unexplained uterine deaths, 33% are of normal birth weight (>2500g), and,therefore,most likely term gestation. Saving Babies further reported that 22.9% of all live births in South Africa was premature and 22.8% of birthswere unexplained intra-uterine deaths. Prematurity is one major complication of chorioamnionitis. When susceptibility for chorioamnionitis is considered during early pregnancy, it is possible to intervene and prevent or even reduce the incidences and complications of chorioamnionitis.A qualitative research study was conducted in three phases. In Phase One(Part One), a theoretically constructed patient scenario of chorioamnionitis was presented to ten midwives,and semi-structured individual interviews were done to elicit information regarding how they screen for and manage chorioamnionitis. In Phase One(Part Two), experienced medical practitioners in the field of obstetrics and gynaecology were individually interviewed, also using semi-structured individual interviewsto gain their views regarding chorioamnionitis as a contributing factor to maternal morbidity and mortality. Qualitative findings in Phase Oneindicated that there is a general lack of knowledge regarding chorioamnionitis among midwives, resulting ininadequate screening, misdiagnosis and mismanagement of the condition. Experienced medical practitioners confirmed that chorioamnionitis is underdiagnosed, misdiagnosed or undiagnosed and underreported,and they hold views that it is difficult to treat and control pregnancy-related infections according to current practice.An integrative literature review was conductedin Phase Twoand literature regarding diagnostic biomarkers, screening options to diagnose chorioamnionitis and management of chorioamnionitis were extracted. After evidence synthesisofPhase Oneand Phase Twodata, a best practice guidelinefor screening and managing viiwomen withchorioamnionitiswas developed usingthe National Institute for Health and Clinical Excellence guideline development approach in Phase Three. The purpose of the best practice guideline for screening and managing women with chorioamnionitis was to provide a guideline onhow to manage women who are at risk and those who present with signs and symptoms of chorioamnionitis at any stage during their pregnancy. Five recommendations were made that involve screening for chorioamnionitisand causative factors, biomarkers to diagnose chorioamnionitis, management of chorioamnionitis that includes pharmacological and non-pharmacological management, and health education to women.Ethics for this research study were guided by the ethical principles and guidelines of the Belmont Report. The trustworthiness of this research study was adopted from Ravitch and Carl,and was based on criticality, reflexivity, collaboration, and rigour. An independent coder and reviewer wereto verify the data that were included in the best practice guideline. Expert reviewersappraised the best practice guidelineusing Appraisal of Guidelines for Research and Evaluation II tools.
  • Full Text:
  • Date Issued: 2020

A business process model for blockchain-based South African real estate transactions

  • Authors: Tilbury, Jack Laurie
  • Date: 2020
  • Subjects: Blockchains (Databases) , Conveyancing -- Technological innovations , Real estate business -- Data processing , Real estate business -- South Africa -- Technological innovations
  • Language: English
  • Type: text , Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10962/148380 , vital:38734
  • Description: The real estate transaction process has been described as inefficient and technologically outdated due to numerous stakeholders and predominantly paper-based operations. Despite the apparent bottlenecks in the current process, the implementation of new technology into the real estate sector has lagged. Several attempts have been made to modernise and digitise the business process but committed integration of assisting technology has lacked attention. This study examined the applicability and potential integration of blockchain technology into the business process of South African real estate transactions. Blockchain’s novelty means that research in this space, especially within South Africa, is limited. Of the research that has been conducted, no models of the business processes for South African or blockchain-based real estate transactions have been constructed. This study provides two business process models, illustrating the two different processes. The main contribution of this paper was an integrated business process model, illustrating how the various processes and stakeholder interactions for South African blockchain-based real estate transactions are conducted on one transaction platform, common to all participating stakeholders. This platform was named the South African Blockchain Land Exchange System (SABLES), which manages and facilitates these transactions in their entirety from start to finish. This model depicts an enhanced business process that provides increased security, transparency, and speed. These benefits will be realised by those who register, adopt, and transact on the platform. Through in-depth interviews, the integrated business process model was assessed. The findings produced a final and combined thematic map, representing the main themes of the analysed interview data, namely blockchain implementation strategies, business process applicability, information technology assimilation, current transaction context, and PropTech 3.0 success factors. The discussion revealed that the current transaction process lacks technological innovation, which increases pressure on the conveyancing role. It was also revealed that there is not only a need within the industry, but a desire, for newer technologies to assist the transaction process. In order to streamline and improve efficiency, business processes should leverage digital records and data, and strive for a solution beyond digitisation, achieving digitalisation. Digitalisation recognises digital documents as official and legal documents as opposed to simply being digital back-ups. This, coupled with the business process models, represent theoretical contributions.
  • Full Text:
  • Date Issued: 2020

A career in photophysicochemical and electrochemical properties of phthalocyanine: A Linstead Career Award paper

  • Authors: Nyokong, Tebello
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/186045 , vital:44458 , xlink:href="https://doi.org/10.1142/S1088424620300037"
  • Description: This manuscript highlights the author’s contributions to phthalocyanine chemistry, especially the applications based on their electrochemistry and photophysicochemistry. In particular, the use of phthalocyanines as electrocatalysts and photocatalysts is presented. For photocatalysis, photodynamic antimicrobial chemotherapy and pollution control using green technologies are highlighted. For electrocatalysis the phthalocyanines are employed for the detection of pollutants and environmentally important molecules. Phthalocyanines are combined with nanomaterials for improved photocatalysis and electrocatalysis.
  • Full Text:
  • Date Issued: 2020

A case study of how a leader shaped the culture of an organisation during a post-merger integration

  • Authors: Zozi, Vuyokazi
  • Date: 2020
  • Subjects: Corporate culture -- South Africa -- East London , Leadership -- South Africa -- East London , Organizational behavior -- South Africa -- East London , Strategic planning -- South Africa -- East London , Mission statements -- South Africa -- East London , Government accountability -- South Africa -- East London , Government corporations -- South Africa -- East London , Consolidation and merger of corporations -- South Africa -- East London , Consolidation and merger of corporations -- Management , Crisis management -- South Africa -- East London , Core competencies -- South Africa -- East London , Resource allocation -- South Africa -- East London , Personnel management -- South Africa -- East London , Communication in management -- South Africa -- East London , Qualitative research
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10962/146643 , vital:38544
  • Description: This research took the form of a case study of the post-merger integration of a government organisation. The study had four objectives, namely to: (1) describe the cultural value of accountability; (2) analyse how strategic leadership and relational leadership roles were exercised to address post-merger integration challenges; (3) analyse how a leader applied selected primary mechanisms to shape organisational culture; (4) analyse how strategic and relational leadership complemented each other in addressing the challenges of post-merger integration and thereby shaping a culture of accountability; and (5) describe how some of the secondary articulation and reinforcing mechanisms supported the culture that was created through primary mechanisms. The literature reviewed, identified some of the critical challenges that are experienced in a post-merger integration, and highlighted the role of leadership in culture formation. The critical challenges that were identified are as follows: What is the vision and organisational purpose? How does the leader structure the organisation? What kind of culture does the leader need to create? How does the leader maintain trust and keep communication with employees? How does a leader build new core competences and develop human capital? Two leadership approaches were adopted, namely strategic and relational leadership. These two leadership approaches were selected because, based on a review of the literature, they appeared to address these post-integration challenges. The roles associated with strategic leadership that were investigated, were creating a vision and purpose for the organisation, developing core competences and developing human capital. From the perspective of relational leadership, this study was concerned with how a leader communicated through regular formal and informal dialogues to keep employees abreast of things, and how the leader built trust. In reviewing the literature linking leadership and culture, the work of Schein (2010) featured prominently. Schein (2010) referred to primary embedding mechanisms that create culture and secondary articulation and reinforcing mechanisms that reinforce or support the culture being created through the primary mechanisms. This study looked at how that happens, and hence six propositions were crafted from the literature. These propositions are as follows: (1) Formal dialogues between the leader and employees demonstrate what the leader pays attention to, measures and controls, which then clarifies what the employees are accountable for. (2) What the leader pays attention to, measures and controls during regular informal interactions between the leader and employees, contributes to strong mutual relationships between them, which promotes ownership and accountability amongst employees for their actions. (3) A leader who behaves consistently when handling critical incidents and organisational crises, is trusted by employees, who then act responsibly and take full responsibility for their actions, and even their mistakes. (4) A leader creates a vision and sense of purpose for the organisation through what he pays attention to, measures and controls, thereby clarifying for employees what they are required to do. (5) A leader who pays attention to developing the organisational core competence and allocates resources to it, instils confidence in his employees with regards to carrying out their own responsibilities. (6) A leader who develops human capital through the allocation of additional resources, thereby instilling confidence in employees who are willing and able to realise or take up their responsibilities. This research adopted a qualitative approach. Data was collected through conducting interviews and the analysis of relevant documents. A deductive thematic analysis of the data was used for the purpose of identifying, analysing and reporting patterns, or themes within the data collected. The research confirmed these propositions as being relevant to the case study. It also confirmed that strategic and relational leadership as reflected in the propositions have complemented one another in the successful implementation of the post-merger integration, thereby shaping a particular culture. It was concluded that the challenges associated with a post-merger integration could not have been addressed through only one of the leadership approaches. The findings of the study also recognised that an architectural role was also required. That is, in a merger, the structure has to be carefully designed and not taken for granted. It was therefore recognised as a critical leadership role. The study considers the implications of the findings and makes recommendations for managers of this organisation, as well as for other organisations that are engaging in a post-merger integration. It further outlines the limitations, delimitations as well as the contribution that the study has made to the body of knowledge. Some of the recommendations made for further research were to analyse how other primary mechanisms that were not part of the propositions may shape the organisational culture; and to research how architectural leadership roles combine with strategic and relational leadership to address post-merger integration challenges. Lastly, this study has explained how leadership, through various mechanisms, shaped a culture of accountability. Other studies can be done using a similar design with different theories of leadership and other mechanisms that apply to shaping other kinds of cultural values.
  • Full Text:
  • Date Issued: 2020

A classification of large wetlands in Africa’s elevated drylands based on their formation, structure, and hydrological functioning using Earth Observation (EO) data and Geographic Information System (GIS)

  • Authors: Lidzhegu, Zwidofhelangani
  • Date: 2020
  • Subjects: Wetlands -- Africa -- Classification , Wetlands -- Africa -- Research , Wetlands -- Africa -- Monitoring , Topographical surveying -- Africa , Hydrological surveys == Africa
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/142668 , vital:38100
  • Description: Due to wetland inaccessibility and limited wetland geomorphological studies, there is limited information on the geomorphological origin and hydrological functioning of different types of wetlands in Africa’s elevated drylands. As a result, there is limited information for the development of a comprehensive wetland classification system that classifies wetlands based on long-term geomorphic processes that determine their formation and shape, their structure and hydrological functioning. Therefore, the current study was designed to classify large wetlands in Africa’s elevated drylands based on processes that determine their formation, and shape their structure and hydrological functioning using remote sensing and Geographic Information System (GIS) techniques. Although wetlands perform a number of hydrological functions including groundwater recharge and water purification, the current study focuses mainly on their flood attenuation function. Detailed analysis of topographic information was undertaken using Shuttle Radar Topographic Mission (SRTM) elevations measured at the scale of 30 m x 30 m. LandsatLook and Google Earth images, tectonic as well as geological data were used as supplementary data for developing an understanding of the origin, structure and hydrological characteristics of wetlands. The Principal Component Analysis (PCA) of wetland environmental variables was used to identify and explain wetland heterogeneity. The results of the study showed that fluvial processes, tectonic history and the evolution of Africa’s landscape played a fundamental role in the formation and evolution of wetlands. This study demonstrates a wide range of processes that contribute to wetland formation, structure and functioning. At one extreme it is clear that tectonic processes may be primarily responsible for the creation of basins that host wetlands. At another extreme, wetlands may be structured primarily by fluvial processes. At a third extreme are wetlands that superficially appear to be structured by fluvial processes, but which have their structures modified by gradual rising of the base level at their distal ends, either through marginal uplift adjacent to rift valleys, or through aggradation of a floodplain that blocks a tributary valley. Overall, the classification of wetlands considered in this study can be summarised into four distinct groupings, with two of these divided further into two groupings each: (1) Tectonic basins with little or no indication of fluvial development (Bahi and Wembere wetlands), (2) Tectonic basins evolving towards a wetland with a structure increasingly shaped by fluvial characteristics (Usangu wetland), (3) Fluvially modified valleys with a local base level at the toe of the wetland such as a resistant lithology or a tectonic control that limits the rate of incision of easily weathered and eroded lithologies, leading to valley widening and longitudinal slope reduction, which are of two distinct types: (a) With a catchment on Kalahari Group sediment that is transported fluvially as bedload, and therefore with no prominent alluvial ridge or backwater depressions (Upper Zambezi and Barotse wetlands), (b) With a catchment that produces abundant fine sediment that is deposited as overbank sediments, leading to channel migration via meandering and to the construction of an elevated alluvial ridge (Lufira wetland), (4) Fluvially modified basins with evidence of gradual elevation of the base level at the toe of the wetland, which are of two types: (a) Tectonic marginal rift valley uplift such that they behave more as depression wetlands rather than as wetlands shaped by fluvial processes (Kafue and Luapula wetlands), (b) Tributary valley wetlands blocked by aggradation of the trunk valley (Lukanga wetland). In conclusion, although few geomorphological studies have been conducted on southern African wetlands because of their inaccessibility, Africa’s surface topography and its historical evolution, as well as aridity, provide an opportunity for illustrating the important role that the long-term tectonic, geological and geomorphological processes play in determining wetland origin, structure and dynamics. GIS methodology and Earth Observation (EO) data on the other hand, provide a practical means for acquiring information on inaccessible and hard to traverse wetland systems. A novel cut-and-fill approach for delineating wetlands from a Digital Elevation Model (DEM) was presented as another way in which GIS methodology and Earth Observation (EO) data can provide practical means for assessing inaccessible and hard to traverse wetland systems.
  • Full Text:
  • Date Issued: 2020

A cloud adoption framework for South African SMEs

  • Authors: Mudzamba, Ronald Ratidzo
  • Date: 2020
  • Subjects: Cloud computing , Cloud computing -- Security measures , Small business -- Technological innovations -- South Africa -- Eastern Cape , Small business -- Information technology -- South Africa -- Eastern Cape , Information technology -- South Africa -- Eastern Cape , Technology-Organisation-Environment (TOE) framework , Small to Medium Enterprises (SMEs)
  • Language: English
  • Type: text , Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10962/148574 , vital:38751
  • Description: Small to Medium Enterprises (SMEs) have been touted as key enablers to the economic development of most countries. Despite growing evidence that most SMEs fail within their initial years, ICTs have been found to add substantial value in facilitating their success. However, in most developing countries, ICT adoption by SMEs has been plagued with a plethora of challenges ranging from poor electricity supply, high ICT costs, lack of ICT expertise to lack of government support. While this might seem problematic for SMEs, the adoption and the use of cloud services mitigates some of these challenges. The problem, however, is that a limited amount of literature has provided guidance with regard to how the cloud adoption process should be carried out by SMEs. The objective of this research, was therefore, to address this by developing a framework that can be used by SMEs to guide them through the cloud adoption process. To this end, thirteen (13) semi-structured interviews were conducted across nine (9) SMEs in the Eastern Cape. The resultant interview transcripts were analysed using an established thematic approach; the result of which allowed for the development of a rich interpretive narrative about SME cloud adoption. Combined with theory from extant literature, this culminated in the development of a framework for cloud services adoption for SMEs in the Eastern Cape.
  • Full Text:
  • Date Issued: 2020

A combined modelling approach for simulating channel–wetland exchanges in large African river basins

  • Authors: Makungu, Eunice J
  • Date: 2020
  • Subjects: Watersheds -- Africa , Watershed management -- Africa , Water resources development -- Africa -- International cooperation , Floodplain management -- Africa , Wetland ecology -- Simulation methods -- Africa , Wetland management -- Africa
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/123288 , vital:35424
  • Description: In Africa, many large and extensive wetlands are hydrologically connected to rivers, and their environmental integrity, as well as their influence on downstream flow regimes, depends on the prevailing channel–wetland exchange processes. These processes are inherently complex and vary spatially and temporally. Understanding channel–wetland exchanges is therefore, indispensable for the effective management of wetlands and the associated river basins. However, this information is limited in most of the river basins containing large wetlands in Africa. Furthermore, it is important to understand the links between upstream and downstream flow regimes and the wetland dynamics themselves, specifically where there are water resource developments that may affect these links (upstream developments), or be affected by them (downstream developments). Hydrological modelling of the entire basin using basin-scale models that include wetland components in their structures can be used to provide the information required to manage water resources in such basins. However, the level of detail of wetland processes included in many basin-scale models is typically very low and the lack of understanding of the wetland dynamics makes it difficult to quantify the relevant parameters. Detailed hydraulic models represent the channel-wetland exchanges in a much more explicit manner, but require relatively more data and time resources to establish than coarser scale hydrological models. The main objective of this study was, therefore, to investigate the use of a detailed hydraulic wetland model to provide a better understanding of channel–wetland exchanges and wetland dynamics, and to use the results to improve the parameterisation of a basin-scale model. The study focused on improving the water resource assessments modelling of three data-scarce African river basins that contain large wetlands: the floodplains of the Luangwa and Upper Zambezi River basins and the Usangu wetland in the Upper Great Ruaha River basin. The overall objective was achieved through a combined modelling approach that uses a detailed high-resolution LISFLOOD-FP hydraulic model to inform the structure and parameters of the GW Pitman monthly hydrological model. The results from the LISFLOOD-FP were used to improve the understanding of the channel–wetland exchange dynamics and to establish the wetland parameters required in the GW Pitman model. While some wetland parameters were directly quantified from the LISFLOOD-FP model results, others, which are highly empirical, were estimated by manually calibrating the GW Pitman wetland sub-model implemented in excel spreadsheets containing the LISFLOOD-FP model results. Finally, the GW Pitman model with the inclusion of the estimated wetland parameters was applied for each basin and the results compared to the available downstream observed flow data. The two models have been successfully applied in southern Africa, with the GW Pitman model being one of the most widely applied hydrological models in this region. To address the issue of data scarcity, during setup of these models, the study mainly relied on the global datasets which clearly adds to the overall uncertainty of the modelling approach. However, this is a typical situation for most of the data scarce regions of the continent. A number of challenges were, however, faced during the setup of the LISFLOOD-FP, mainly due to the limitations of the data inputs. Some of the LISFLOOD-FP data inputs include boundary conditions (upstream and downstream), channel cross-sections and wetland topography. In the absence of observed daily flows to quantify the wetland upstream boundary conditions, monthly flow volumes simulated using the GW Pitman monthly model (without including the wetland sub-model) were disaggregated into daily flows using a disaggregation sub-model. The simulated wetland inflows were evaluated using the observed flow data for downstream gauging stations that include the wetland effects. The results highlighted that it is important to understand the possible impacts of each wetland on the downstream flow regime during the evaluations of the model simulation results. Although the disaggregation approach cannot be validated due to a lack of observed data, it at least enables the simulated monthly flows to be used in the daily time step hydraulic model. One of the recommendations is that improvements are required in gauging station networks to provide more observed information for the main river and the larger tributary inflows into these large and important wetland systems. Even a limited amount of newly observed data would be helpful to reduce some of the uncertainties in the combined modelling approach. The SRTM 90 m DEM (used to represent wetland topography) was filtered to reduce local variations and noise effects (mainly vegetation bias), but there were some pixels that falsely affect the inundation results, and the recently released vegetation-corrected DEMs are suggested to improve the simulation results. Channel cross-section values derived from global datasets should be examined because some widths estimated from the Andreadis et al. (2013) dataset were found to be over-generalised and did not reflect widths measured using high-resolution Google Earth in many places. There is an indication that channel cross-sections digitised from Google Earth images can be successfully used in the model setup except in densely vegetated swamps where the values are difficult to estimate, and in such situations, field measured cross-section data are required. Small channels such as those found in the Usangu wetland could play major role in the exchange dynamics, but digitising them all was not straightforward and only key ones were included in the model setup. Clearly, this inevitably introduced uncertainties in the simulated results, and future studies should consider applying methods that simplify extractions of most of these channels from high-resolution images to improve the simulated results. The study demonstrated that the wetland and channel physical characteristics, as well as the seasonal flow magnitude, largely influence the channel–wetland exchanges and wetland dynamics. The inundation results indicated that the area–storage and storage–inflow relationships form hysteretic curves, but the shape of these curves vary with flood magnitude and wetland type. Anticlockwise hysteresis curves were observed in both relationships for the floodplains (Luangwa and Barotse), whereas there appears to be no dominant curve type for the Usangu wetlands. The lack of well-defined hysteretic relationships in the Usangu could be related to some of the difficulties (and resulting uncertainties) that were experienced in setting up the model for this wetland. The storage–inflow relationships in all wetlands have quite complex rising limbs due to multiple flow peaks during the main wet season. The largest inundation area and storage volume for the Barotse and Usangu wetlands occurred after the peak discharge of the wet season, a result that is clearly related to the degree of connectivity between the main channel and those areas of the wetlands that are furthest away from the channel. Hysteresis effects were found to increase with an increase in flood magnitudes and temporal variations in the wetland inflows. Overall, hysteresis behaviour is common in large wetlands and it is recommended that hysteresis curves should be reflected in basin-scale modelling of large river basins with substantial wetland areas. At a daily time scale, inflow–outflow relationships showed a significant peak reduction and a delayed time to peak of several weeks in the Barotse and Usangu wetlands, whereas the attenuation effects of the Luangwa floodplain are minimal. To a large extent, the LISFLOOD-FP results provided useful information to establish wetland parameters and assess the structure of Pitman wetland sub-model. The simple spreadsheet used to estimate wetland parameters did not account for the wetland water transfers from the upstream to the next section downstream (the condition that is included in the LISFLOOD-FP model) for the case when the wetlands were distributed across more than one sub-basin. It is recommended that a method that allows for the upstream wetland inflows and the channel inflows should be included in the spreadsheet. The same is true to the Pitman model structure, and a downstream transfer of water can be modelled through return flows to the channel. The structure of the wetland sub-model was modified to allow an option for the return flows to occur at any time during the simulation period to provide for types of wetlands (e.g. the Luangwa) where spills from the channel and drainage back to the channel occur simultaneously. The setup of the GW Pitman model with the inclusion of wetland parameters improved the simulation results. However, the results for the Usangu wetlands were not very satisfactory and the collection of additional field data related to exchange dynamics is recommended to achieve improvements. The impacts of the Luangwa floodplain on the flow regime of the Luangwa River are very small at the monthly time scale, whereas the Barotse floodplain system and the Usangu wetlands extensively regulate flows of the Zambezi River and the Great Ruaha River, respectively. The results highlighted the possibilities of regionalising some wetland parameters using an understanding of wetland physical characteristics and their water exchange dynamics. However, some parameters remain difficult to quantify in the absence of site-specific information about the water exchange dynamics. The overall conclusion is that the approach implemented in this study presents an important step towards the improvements of water resource assessments modelling for research and practical purposes in data-scarce river basins. This approach is not restricted to the two used models, as it can be applied using different model combinations to achieve similar study purpose.
  • Full Text:
  • Date Issued: 2020

A comparative analysis of social media brand image of insurance companies in South Africa: a longitudinal study

  • Authors: Gudu, Daniel
  • Date: 2020
  • Subjects: Social media -- South Africa , Internet marketing -- South Africa , Chernoff faces , Ínsurance companies -- South Africa -- Marketing , Insurance companies -- South Africa -- Case studies , Multivariate analysis -- Graphic methods
  • Language: English
  • Type: text , Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10962/144277 , vital:38327
  • Description: Social media is changing the way business is conducted. Almost five billion videos are watched on YouTube every single day. Social media has an extensive worldwide presence. Out of the total global population of over 7,5 billion people, over 4 billion are internet users. Of these, over 3 billion are active on social media. Social media is very influential in today's decision-making processes. Businesses must integrate social media into their strategies. The purpose of this research was to investigate the use of a novel method, Chernoff Faces, to assess and compare the social media brand images of six insurance companies in South Africa based on social conversation measurement. The intention of research was towards observing existing situations at hand and pointing out the game changers that can provide the industry with a new leap. Social media are multidimensional and understanding them requires tracking different measures simultaneously. Integrating social media into a communication strategy leads to a problem in finding the best way to portray and communicate multivariate data. It is essential to find the best way to represent and transmit the data so that marketing executives can quickly and easily monitor changes in brand images. Previous studies have successfully proved the possibility of using this method to gauge a "snapshot in time." This study took the concept further by closely monitoring the results for a set of brands over a period to account for the dynamic nature of social media. Accordingly, the study was a longitudinal study of 30 days. Data on the insurance companies was collected from Social Mention, a social media search and analysis platform that aggregates user-generated content into a single stream of information. A tool in the statistical software Stata, Chernoff's faces, was used to analyse the results by generating facial expressions to the metrics associated with the social mentions of each of the insurance companies. The resulting facial expressions were then analysed to recognise the more favourable and stable brands and those that need appropriate risk management. Managing Social Media is challenging as managers must always keep it as positive as possible. Brand managers, therefore, need a better tool to gauge the mood in social media conversations due to the fast-changing nature of social media and the importance of social media to business especially insurance.
  • Full Text:
  • Date Issued: 2020

A comparative analysis of the effects of different Levels of Education on growth in African Economies

  • Authors: Mkhosana, Nomathamsanqa
  • Date: 2020
  • Subjects: Economic development -- Effect of education on , Education -- Economic Aspects
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10948/50393 , vital:42161
  • Description: The economic growth and development of a country depend on the educational opportunities available to its citizens. Education is deemed to influence economic growth via improved labour productivity particularly through knowledge and skills accumulation by promoting technological improvement and innovation. The aim of the study was to highlight the importance of each level of education on economic growth of African countries. The objective of the study was to find which level of education (primary, secondary and tertiary) has the most significant effect on economic growth. To obtain this objective, the study using two panel cointegration methods, the fully modified ordinary least squares (FMOLS) and dynamic ordinary least squares (DOLS) method applied to data covering the period of 2000 to 2017, the study aimed at sampling 10 educated economies and 10 advanced economies in Africa, since South Africa and Kenya belong in both categories, the study a total of 18 African economies. The results of the study show discrepancies, that is, primary and secondary education being most beneficial towards more advanced economies whilst only tertiary education is beneficiary towards more educated African countries. Policy implications are provided.
  • Full Text:
  • Date Issued: 2020

A comparative analysis of the use of participatory practices by indigenous trusts and mainstream development NGOs in Zvimba Communal Area Zimbabwe

  • Authors: Mbanje, Bowden Bolt
  • Date: 2020
  • Subjects: Caritas Zimbabwe , Zvimba Community Share Ownership Trust (ZvCSOT) , Non-governmental organizations -- Zimbabwe -- Zvimba District , Community development -- Zimbabwe -- Zvimba District , Rural development -- Zimbabwe -- Zvimba District , Zvimba Communal Land (Zimbabwe)
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/167099 , vital:41437
  • Description: This thesis compares the extent to which participatory practices have been used by Caritas Zimbabwe, a mainstream NGO, and the Zvimba Community Share Ownership Trust (ZvCSOT), an indigenous Trust, in Zvimba District, Zimbabwe. Participatory development initiatives are common practice in NGO and government development work in Zimbabwe. The thesis begins with a discussion of two aspects of participatory development (PD). Firstly, PD is discussed in relation to decentralization processes where central government transfers administrative and financial authority to sub-national government units in order to enhance the participation of rural communities in development interventions. Secondly, PD is discussed in relation to the increased role of NGOs in development work. During the 1980s and 1990s, shifts in development thinking resulted in NGOs being perceived as important actors who could attend to the development gaps left by an economically incapacitated state. Both NGOs and sub-national government units were seen to be closer to rural communities and so were thought to be in a better position to enhance the participation of these communities in meaningful development projects. An analysis of the practices of the NGO and CSOT under consideration in this study shows that while there has been much rhetorical commitment to participation, community participation in the development interventions of the NGO and the CSOT is inadequate. In introducing and implementing development interventions, there has been a tendency by both the NGO and CSOT to give priority to organizational preferences over local needs. While recognizing the participatory efforts made by mainstream development NGOs (Caritas in particular) and indigenous Trusts (Zvimba Community Share Ownership Trust in particular) in Zimbabwe, this thesis also considers the impact of other factors on participatory development initiatives. A major observation from the study is that in as much as we expect genuine participatory approaches which include grassroots communities’ inputs from the project’s conceptualization all the way to its evaluation, the challenge is that the elites at the higher level (central government and donor offices) have their own development preferences and interests while the elites at the lower levels (local government and NGO offices) also have their own priorities and needs. Consequently, local communities tend to be confined to implementing development projects foisted on them by elites at the higher level as well as those at the lower level. Worse still, the study shows that elites at the lowest level (community) sometimes hijack or take advantage of the imposed projects. Participation has been stalled by elites at various levels of the participatory development ladder. Thus, unless power imbalances are seriously addressed at all levels, participatory development will remain elusive.
  • Full Text:
  • Date Issued: 2020

A comparative analysis with selected jurisdictions of structural challenges facing the South African office of the tax ombud

  • Authors: Mothiba, Boitumelo Charity
  • Date: 2020
  • Subjects: South Africa. Office of the Tax Ombud , Tax administration and procdure -- South Africa , Taxpayer advocates -- South Africa
  • Language: English
  • Type: text , Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10962/140360 , vital:37882
  • Description: The Office of the Tax Ombud is critical in the protection of South African taxpayers' rights. The office has only been in existence for a little over five years and to ensure that it fulfils the purpose for which it was established, it must be properly structured. This includes that it ought to be independent from any external influence and manipulation. Any such external influence on the Tax Ombud creates the risk that the general public will lose confidence in the Tax Ombud as an independent recourse. The study, therefore, is designed to review the structure relating to the independence and powers of the South African Tax Ombud. The study assesses and evaluates the legislative safeguards of the structure of the Tax Ombud office in order to determine whether the legislative framework (the Tax Administration Act) safeguarding the Office of the Tax Ombud is adequate to ensure its independence and also to ensure a strengthened structure, without interference in the decision-making process of the office. To achieve this, a comparative analysis was made with selected foreign institutions of Tax Ombudsmen, or equivalent institutions, in order to draw from the best international practice. The study found that the structure of the Office of the Tax Ombud is relatively weak and does not fully provide the legislative powers to protect taxpayers from the well-resourced South African Revenue Service. The study also revealed that most of the institutional features in the structure of the South African Tax Ombud were found to be in line with standard international practice. The study has made recommendations aimed at strengthening the structure of the South African Tax Ombud by suggesting reforms in the legislative framework of the Tax Ombud.
  • Full Text:
  • Date Issued: 2020

A comparative mineralogical and geochemical study of manganese deposits in the Postmasburg Manganese Field, South Africa

  • Authors: Thokoa, Mamello
  • Date: 2020
  • Subjects: Manganese ores -- South Africa -- Postmasburg , Geology -- South Africa -- Postmasburg
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/167609 , vital:41496
  • Description: The Postmasburg Manganese Field (PMF), located in the Northern Cape Province of South Africa, is host to some of the largest deposits of iron and manganese metal in the world. These deposits are restricted to a geographical area known as the Maremane Dome, an anticlinal structure defined by folded dolostones of the Campbellrand Subgroup and overlying ironformations of the Asbestos Hills Subgroup of the Neoarchaean-Palaeproterozoic Transvaal Supergroup. Manganese ores associated with the Maremane Dome have been divided into two major classes in the literature: the Wolhaarkop breccia-hosted massive ores of the Eastern Belt, as well as the shale-associated ores of the Western Belt. The Eastern Belt ores have been classed as siliceous in nature, while the Western Belt deposits are reported to be typically ferruginous. These divisions were made based on their varying bulk chemical and mineralogical compositions in conjunction with their different stratigraphic sub-settings. Presently, both deposit types are explained as variants of supergene mineralisation that would have formed through a combination of intense ancient lateritic weathering in the presence of oxygen, extreme residual enrichments in Mn (and Fe), and accumulations in karstic depressions at the expense of underlying manganiferous dolostones. This study revisits these deposits and their origins by sampling representative end-member examples of both Eastern Belt and Western Belt manganese ores in both drillcore (localities Khumani, McCarthy and Leeuwfontein), and outcrop sections (locality Bishop). In an attempt to provide new insights into the processes responsible for the genesis of these deposits, the possibility of hydrothermal influences and associated metasomatic replacement processes is explored in this thesis. This was achieved using standard petrographic and mineralogical techniques (transmitted and reflected light microscopy, XRD , SEM-EDS and EMPA), coupled with bulk-rock geochemical analysis of the same samples using a combination of XRF and LAICP- MS analyses. Combination of field observations, petrographic and mineralogical results, and geochemical data allowed for the re-assessment of the different ore types encountered in the field. Comparative considerations made between the bulk geochemistry of the different end-member ore types revealed no clear-cut compositional distinctions and therefore do not support existing classifications between siliceous (Eastern Belt) and ferruginous (Western Belt) ores. This is supported by trace and REE element data as well, when normalised against average shale. The geochemistry reflects the bulk mineralogy of the ores which is broadly comparable, whereby braunite and hematite appear to be dominant co-existing minerals in both Eastern Belt (Khumani) and Western Belt (Bishop) ore. In the case of the McCarthy locality, manganese ore is cryptomelane-rich and appears to have involved recent supergene overprint over Eastern Belt type ore, whereas the Leeuwfontein ores are far more ferruginous than at any other locality studied and therefore represent a more complex, hybrid type of oxide-rich Mn mineralisation (mainly bixbyitic) within massive hematite iron ore. In terms of gangue mineralogy, the ores share some close similarities through the omnipresence of barite, and the abundance of alkalirich silicate minerals. Eastern Belt ores contain abundant albite and serandite whereas the main alkali-rich phase in Western Belt ores is the mineral ephesite. In both cases, Na contents are therefore high at several wt% levels registered in selected samples. The afore-mentioned alkali enrichments have been variously reported for both these deposit types. The occurrence of high alkalis cannot be explained through classic residual or aqueous supergene systems of ore formation, as proposed in prevailing genetic models in the literature. Together with the detection of halogens such as F and Br through SEM-EDS analyses of ore from both belts, the alkali enrichments suggest possible hydrothermal processes of ore formation involving circulation of metalliferous sodic brines. Selected textural evidence from samples from both ore belts lends support to fluid-related models and allow the proposal for a common hydrothermal-replacement model to have been responsible for ore formation across the broader Maremane Dome region.
  • Full Text:
  • Date Issued: 2020

A Comparative Study of Bootstrapping Techniques for Inventory Control

  • Authors: Frederick, Lauren
  • Date: 2020
  • Subjects: Computer bootstrapping -- Inventory control
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/48335 , vital:40849
  • Description: Setting correct inventory levels is an important business consideration in order to minimise inventory investment while at the same time ensuring sufficient inventory levels to meet customer demand. Inventory management has a significant impact on both financial and customer service aspects of a business. Selecting appropriate inventory levels requires that products’ lead time demand be accurately estimated in order to calculate the reorder point. The purpose of this study was to empirically determine whether bootstrapping methods used to estimate the lead time demand distribution and reorder point calculation could match or even outperform a standard parametric approach. The two bootstrapping methods compared in this research included variations of those presented by Bookbinder and Lordahl [1989] and do Rego and de Mesquita [2015]. These were compared to the standard parametric approach common in practice which makes use of the Normal distribution for modelling lead time demand. The three reorder point calculation methods were each incorporated into the inventory policy simulations using data supplied by a South African automotive spare parts business. The simulations covered a period of twelve months and were repeated for multiple service levels ranging from 70 to 99 percent. Results of the simulations were compared at a high level as well as for groups of items identified using segmentation techniques which considered different item demand and lead time characteristics. Key findings were that the Normal approximation method was far superior in terms of the service level metric, while the variation of the Bookbinder and Lordahl [1989] method adopted in this study presented possible cost benefits at lower service levels.
  • Full Text:
  • Date Issued: 2020

A comparative study of conceptualisations and practices of inclusion as an aspect of social justice in three teacher education institutions in Canada, South Africa and Zimbabwe

  • Authors: Musara, Ellison
  • Date: 2020
  • Subjects: Social justice and education , Teachers -- Training of -- Canada , Teachers -- Training of -- South Africa , Teachers -- Training of -- Zimbabwe , Educational sociology -- Canada , Educational sociology -- South Africa , Educational sociology -- Zimbabwe , Educational equalization , Inclusive education , Education -- Moral and ethical aspects , Critical realism
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/144138 , vital:38314
  • Description: This study sought to examine understandings and practices of inclusion as social justice in teacher education programmes in three countries: Canada, South Africa and Zimbabwe. While inclusive education has become an issue of increasing importance globally, contemporary research shows that not much attention has been given to the preparation of teachers as a key element in developing inclusive education systems. Recognising that pre-service teacher education is vital to the success and continued development of inclusive educational practice, the purpose of this qualitative study was to better understand the ways in which inclusion is understood and practiced in the field of teacher education. Using Roy Bhaskar’s (1978) critical realism as a metatheory and drawing on Fraser’s substantive theory of social justice (2008, 2009) and Tronto’s ethic of care (1993, 2013), this study explored the extent to which teacher education faculty and teacher candidates understood and practiced inclusion as an aspect of social justice. The data used in this study was generated through individual and focus group interviews and document analysis in three higher education institutions, one in each of the three countries. In Canada, four teacher educators took part in the interviews while five teacher candidates participated in the focus group. Similarly, in South Africa, three teacher educators and eight teacher candidates participated, and in Zimbabwe, four teacher educators and eight teacher candidates took part in the study respectively. Findings from the study revealed that inclusion still means different things to different people, reflecting contrasting theoretical and ideological orientations from which inclusion is considered, while still remaining a major educational policy concern in all three countries. In the Canadian and South African institutions, inclusion is viewed more in terms of systemic educational change in pursuit of equity, social justice and equal educational opportunities for all learners. In the Zimbabwean institution, the primary focus of inclusion remains creating conditions that make it possible for students with disabilities to overcome barriers to learning and participation by providing specialist educational measures and interventions intended to respond to specific forms of impairment. As a comparative study, it is hoped that this study will contribute to the knowledge of variations and patterns in the ways in which inclusive education is shaped by societal forces such as political, economic and cultural conditions.
  • Full Text:
  • Date Issued: 2020

A comparative study of the effect of different stabilizers on the critical quality attributes of self-assembling nano co-crystals

  • Authors: Witika, Bwalya A , Smith, Vincent J , Walker, Roderick B
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/183224 , vital:43931 , xlink:href=" https://doi.org/10.3390/pharmaceutics12020182"
  • Description: Lamivudine (3TC) and zidovudine (AZT) are antiviral agents used orally to manage HIV/AIDS infection. A pseudo one-solvent bottom-up approach was used to develop and produce nano co-crystals of 3TC and AZT. Equimolar amounts of 3TC dissolved in de-ionized water and AZT in methanol were rapidly injected into a pre-cooled vessel and sonicated at 4 °C. The resultant suspensions were characterized using a Zetasizer. The particle size, polydispersity index and Zeta potential were elucidated. Further characterization was undertaken using powder X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, and energy dispersive X-ray spectroscopy scanning electron microscopy. Different surfactants were assessed for their ability to stabilize the nano co-crystals and for their ability to produce nano co-crystals with specific and desirable critical quality attributes (CQA) including particle size (PS) less than 1000 nm, polydispersity index (PDI) less than 0.500 and Zeta potential (ZP) less than −30 mV. All surfactants produced co-crystals in the nanometer range. The PDI and PS are concentration-dependent for all nano co-crystals manufactured while only ZP was within specification when sodium dodecyl sulfate was used in the process.
  • Full Text:
  • Date Issued: 2020

A comparative study of the photophysicochemical and photodynamic activity properties of meso-4-methylthiophenyl functionalized Sn (IV) tetraarylporphyrins and triarylcorroles

  • Authors: Dingiswayo, Somila , Babu, Balaji , Prinsloo, Earl , Mack, John , Nyokong, Tebello
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/186157 , vital:44469 , xlink:href="https://doi.org/10.1142/S1088424620500273"
  • Description: Tin(IV) complexes of a 4-methylthiophenyl functionalized porphyrin (1-Sn) and its corrole analogue (2-Sn) were synthesized so that their photophysicochemical properties and photodynamic activities against MCF-7 breast cancer cells could be compared. Singlet oxygen luminescence studies revealed that 1-Sn and 2-Sn have comparable ΦΔΦΔ values in DMF of 0.59 and 0.60, respectively, while the IC5050 values after irradiation of MCF-7 cells for 30 min with a Thorlabs 625 nm LED (432 J · cm−2)−2) were determined to be 12.4 and 8.9 μμM. The results demonstrate that the cellular uptake of 2-Sn and its molar absorptivity at the irradiation wavelength play a crucial role during in vitro cytotoxicity studies.
  • Full Text:
  • Date Issued: 2020

A comparative study of the tax measures for persons with disabilities in South Africa with those of Canada and the Republic of Ireland

  • Authors: Currie, Natasha
  • Date: 2020
  • Subjects: People with disabilities -- Taxation -- South Africa , People with disabilities -- Taxation -- Law and legislation -- South Africa , People with disabilities -- Taxation -- Canada , People with disabilities -- Taxation -- Law and legislation -- Ireland , People with disabilities -- Taxation -- Ireland
  • Language: English
  • Type: text , Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10962/170746 , vital:41956
  • Description: Literature indicates that tax relief measures for persons with disabilities are important as they align with the principle of equity in the allocation of the tax burden. They are a government intervention that assists in decreasing the financial burden of medical care for persons with disabilities. The right of persons with disabilities to an adequate standard of living is contained in the landmark Convention on the Rights of Persons with Disabilities and Optional Protocol, a treaty of the United Nations, which South Africa ratified in 2007. The objective of the research was to provide a comparative study of tax relief measures for persons with disabilities in South Africa with those of Canada and the Republic of Ireland, with a view to identifying potential areas for improvement in South Africa. The requisite information was primarily collected through an extensive analysis of the tax legislation in the jurisdictions. The research found that tax relief measures for persons with disabilities and their families in South Africa are limited when compared with those of Canada and the Republic of Ireland. The comparative study identifies a number of potential tax relief measures for implementation in South Africa.
  • Full Text:
  • Date Issued: 2020

A comparison between the responsiveness of selected physiological and subjective mental workload indicators during real-world driving scenarios

  • Authors: Schmidtke, Nadia-Jasmine
  • Date: 2020
  • Subjects: Automobile driving -- Physiological aspects , Automobile driving -- Psychological aspects , Automobile drivers -- Health and hygiene , Mental fatigue , Mental work -- Case studies
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/148115 , vital:38711
  • Description: Sub-optimal levels of mental workload in automobile drivers is a risk factor for road accidents. However, mental workload as a construct cannot be directly measured. Common indicators of mental workload include heart rate frequency and variability, eye motion and subjective rating tools. Namely, the National Aeronautics and Space Administration Task Load Index (NASA-TLX), its modified, unweighted version called the Raw-TLX, and the Rating Scale of Mental Effort (RSME). Comparisons between the suitability and responsiveness of these mental workload indicators have been almost exclusively examined in driving simulators. However, real-world driving research is important as even high-fidelity simulators cannot capture the complexity of driving scenarios. Hence, this research aimed to compare the suitability and responsiveness of these mental workload indicators in response to real-world driving scenarios. Six participants drove along a set route for an hour while wearing a heart rate monitor and eye tracker. A dashcam was used to capture footage of the different driving scenarios encountered. The set route comprised of driving through the industrial, residential, provincial main road and Rhodes University campus areas. RSME scores were taken during brief stops after driving though each zone. The NASA-TLX questionnaire was administered on completion of the drive and analysed later as the modified Raw-TLX version. The data collected in response to the encountered driving scenarios were sorted into three meta-groupings. (1) Data was segmented according to the different areas that participants drove through. This was termed Area Events and were long duration scenarios of between five and thirty minutes. These driving scenarios were further segmented into two meta-groups with short duration driving scenarios (< 90 seconds). (2) The Common Events meta-group consisted of driving scenarios that were encountered by all participants. These were scenarios were anticipated by drivers. (3) The All Events meta-group was grouped according to all the driving scenarios that were encountered by participants. It consisted of both anticipated and unanticipated driving scenarios of short durations. Data were further analysed using a method of systematically selecting a threshold value for each mental workload indicator. Responses to driving scenarios which surpassed the threshold were considered indicative of an increase in mental workload. The total frequency of higher mental workload events was used as a determiner responsiveness (or ‘sensitivity’) for each mental workload indicator. Mental workload indicators were evaluated for their responsiveness and suitability for assessing mental workload. Results found blink frequency to be a responsive mental workload indicator for all categories of driving scenarios. Blink frequency and duration were the most responsive short duration mental workload indicators. Furthermore, the indicators were able to distinguish between higher and lower mental workload driving scenarios. However, blink parameters are also sensitive to driver fatigue and drowsiness. Further research on distinguishing mental workload from that of fatigue in response to real-world driving was recommended. Pupil diameter, fixation duration, saccade saccade duration and saccade amplitude were found to be responsive short duration mental workload indicators. However, these measures were not determined to be suitable for real-world driving applications. Pupil diameter was confounded by changing illumination levels. Fixation and saccade responses were confounded by the driving task itself as gaze could not be accounted for. For long duration driving scenarios heart rate frequency, heart rate variability: high-frequency power, blink frequency and RSME were found to be responsive and suitable MWL indicators. The Raw-TLX results could not be assessed for responsiveness as it was administered once. However, it was confirmed as a suitable cumulative mental workload indicator in the application of real-world driving. The moderate levels of workload reported by participants agreed with the experimental protocol that prevented inducing sub-optimal mental workload. Blink frequency shows promise as a responsive and suitable mental workload indicator for different types of driving scenarios. More research is needed regarding the assessment of mental workload during short durations using blink frequency and blink duration. For driving durations between five and thirty minutes long, further research into heart rate frequency, heart rate variability: high frequency power, and the RSME was recommended.
  • Full Text:
  • Date Issued: 2020
  • Disclaimer
  • Privacy
  • Copyright
  • Contact