ResearchSpace
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The tracking performance of equity exchange traded funds: a consideration of fund replication strategy, fund domicile and crisis period.
(2024) Naidoo, Prianca.; Mccullough, Kerry-Ann Frances.
An Exchange Traded Fund (ETF) is an investment vehicle that issues securities that are essentially claims on an underlying pool of assets. Tracking error measures, the ability of traditional passive ETFs to replicate the returns of their respective underlying index accurately. This measure is commonly reported for all funds with a mandate to replicate some benchmark index. Despite the primarily passive nature of ETFs, fund managers can apply active investment management techniques to them. The application of active management to these funds may include the respective index holding an actively selected basket of securities or entering derivative contracts that deliver the performance of an index, or some mixture of the two. The importance of looking at the passive and active characteristics of funds corresponds to the replication strategies followed by ETFs. Here replication refers to the concept of mirroring the returns of a benchmark index with the returns of an ETF. Bloomberg Professional’s categorisation of replication strategies shows that ETFs replicate their benchmark indices using the following strategies: full physical, stratified sampling, optimization, synthetic and leveraged replication. This study analyses the tracking performance of 52 equity-backed ETFs, focusing on replication strategies, fund domicile, and crisis period. Four methods of tracking error estimation are applied to the ETF sample which have an inception date before 1 January 2006 or 1 January 2012 for the fund replication and domicile analyses due to the observed lack of ETFs following certain replication strategies and domiciled in emerging markets with an inception before 2006. For the crisis analysis the research period spans 18 years to account for the documented price impacts the 2008/2009 Global Financial Crisis (GFC) and the COVID-19 pandemic had on various indices and their replicating funds. We find that overall partial physically replicated ETFs provide superior tracking performance. Full physically replicated ETFs exhibit the highest level of tracking error. Synthetic ETFs demonstrate superior tracking performance in comparison to full physical ETFs. Considering the same underlying benchmark index, leveraged ETFs with lower leverage multipliers exhibit lower levels of tracking errors than their counterparts. ETFs domiciled in developed markets limit tracking errors to a greater extent than emerging market ETFs and synthetic ETFs show superior tracking performance when tracking emerging market indices. All fund replication strategies (noting that leveraged ETFs are excluded in this section of the analysis) for both emerging and developed market ETFs show increases in tracking error during the GFC and the COVID-19 pandemic. Optimized ETFs exhibited the highest increase in tracking error during the GFC while full physically replicated ETFs exhibited the highest increase during the pandemic. Synthetic ETFs showed the most resilience to the effects of the pandemic. Emerging ETFs exhibited
higher increases in tracking error during both crises in comparison to those in developed markets. This study provides both institutional and individual investors with valuable knowledge on the consideration of fund replication strategy, fund domicile and the performance effects of documented crisis periods when selecting an appropriate ETF. Investors and portfolio managers are provided with relevant insights on which type of ETF replication to follow in countries with different development levels and during volatile market periods. Partial physical replication provides superior tracking performance when focusing solely on replication strategy. Synthetic ETFs are recommended when investing in emerging market indices and aiming to minimize exposure to volatile markets marked by crises.
Performance comparison between gas generator and electrically pumped rocket engines under ablative and regenerative cooling.
(2024) Silver, Jordan.; Brooks, Michael John.; Snedden, Glen Campbell.; Cooper, Ryan William Neil.
In recent years, there has been a dramatic advancement in the global satellite industry, with new technologies allowing for smaller and more powerful satellites to be developed. Despite this, South Africa and other African countries developing satellite technologies still depend on foreign launch services as there is no indigenous capability in Africa, incurring additional costs and delays. Against this backdrop, the University of KwaZulu-Natal’s (UKZN) Aerospace Systems Research Institute (ASRI) is pursuing the development of a two-stage Commercial Launch Vehicle (CLV) to provide South Africa with a sovereign launch capability. ASRI is currently developing the booster engine for CLV - the South AFrican FIrst Rocket Engine (SAFFIRE). The booster stage will utilize a cluster of nine of the SAFFIRE engines, and the second stage will use a vacuum derivative of the SAFFIRE engine called SAFFIRE-V and will give CLV the envisioned payload capacity of 200 kg to a 500 km Sun Synchronous Orbit (SSO). Although the design of the SAFFIRE engine is largely complete in terms of injector design, combustion chamber and nozzle geometry, and thrust output, the feed cycle responsible for delivering the propellants to the combustion chamber is undecided. In this report, the gas generator and electropump cycles are under consideration to supply propellants to the SAFFIRE and SAFFIRE-V chambers. In addition, although the chambers are currently ablatively cooled, ASRI remains interested in the possibility of using regenerative cooling. This study, therefore, considers the gas generator and electropump cycles under both cooling methods to identify which SAFFIRE engine combination can provide the best performance for CLV. To measure the performance of each engine combination, the payload mass capabilities of a hypothetical CLV are calculated using results attained from 1- dimensional simulations run in Flownex®, models coupled with Mass Estimating Relationships (MER) that evaluate the components that make up a two-stage liquid rocket engine. The performance comparison found that each engine configuration exceeded the set payload capacity of 200 kg. For the electropump cycle, the ablative and regenerative engines achieved payload masses of 303 kg and 290 kg, respectively. The gas generator performed even better due to a lower dead mass than the electropump cycle, achieving payload masses of 392 kg and 386 kg, respectively. For both cycles, the ablatively cooled rocket engines had better payload capabilities than the regeneratively cooled engines due to a regeneratively cooled engine having a smaller expansion ratio. When the expansion ratios were made the same, the regeneratively cooled engines achieved a payload capacity of 308 kg and 405 kg for the electropump and gas generator cycles, respectively, due to the increased thrust from the heated fuel, which has an increased energy density, producing more thrust. When the dead mass of the electropump cycle was decreased by ejecting the depleted battery packs for each engine stage during the launch, the electropump payload deficit decreased from 98 kg to 29 kg for the ablative engines and 96 kg to 32 kg for the regenerative engines. Based on this study, the best performing SAFFIRE engine configuration is a gas generator cycle with ablative cooling, giving the conceptual CLV rocket a payload of 392 kg to 500 km Sun Synchronous Orbit.
Development of an injector test rig for shear thinning gel propellants.
(2024) Mdhluli, Thabang.; Brooks, Michael John.; Velthuysen, Timothy Johnathan.
This work describes the development of an injector test rig to characterise the behavior of shear-thinning gelled rocket propellants. The work falls under a broader program of research into gel propellants conducted by the Aerospace Systems Research Institute (ASRI). Gels represent a new class of propellant for rocket propulsion applications. They offer potential advantages over conventional liquid and solid propellants but their behaviour through injector orifices is poorly understood. Consequently, there is no standardised design procedure for gelled propellant injectors, although computational fluid dynamic (CFD) methods have shown potential. The aim of this research was to design, build and commission an injector test rig utilising single-element impinging injectors to generate experimental data on gel sprays such as breakup length, and droplet size. The rig is intended to inform gel injector design methodologies by providing experimental data against which CFD-generated simulations can be compared and refined. MATLAB® image processing tools were used to analyse spray sheet images and quantify the resulting fluid structures generated by the test rig. The study included the design and manufacture of the propellant/simulant feed system, injector insert, injector manifold, frame and propellant/simulant supply tank. Two adjustable converging injection orifices were used to form spray sheets at 45°, 60° and 90° impinging angles. For testing purposes, two water-based simulants were formulated using hydrocolloid xanthan and guar gum gelling agents at 0.5, 1.0 and 1.5 wt%. Rheological characterisation of the gels was performed to verify their shear-thinning behavior using a rotational rheometer. Spray sheets were then generated at injector pressure drops in the range of 140 kPa to 1400 kPa. A MATLAB® model of the system was developed to establish control parameters for the desired outputs and the rig was controlled via a LabVIEWTM application. The rig provides a platform for further research into the behavior of gelled rocket propellants, with an intended focus on hydroxylamine nitrate (HAN) and ammonium dinitramide (ADN).
Exploring the isiZulu translation process of medical content at University of kwaZulu Natal Medical School.
(2024) Dlamini, Sinethemba.; Gokool, Roshni.; Dlamini, Phindile.
Communication is essential for healthcare practitioners who intend to understand their patients. KwaZulu-Natal has the largest isiZulu-speaking population in South Africa. In some parts of KwaZulu-Natal, especially in the rural areas, many patients are monolingual. Therefore, it is vital that isiZulu and/or other African indigenous languages be integrated into health sciences curricula across the country. At UKZN (University of KwaZulu-Natal), isiZulu has made significant inroads into the MBChB (i.e. Bachelor of Medicine and Bachelor of Surgery) curriculum. However, more research and further integration of isiZulu is urgently needed. This study explores the isiZulu translation process of medical content used to develop a web-based learning tool at the Nelson R Mandela School of Medicine to assist non-isiZulu-speaking students in enhancing isiZulu for clinical communication. Translation is a way of building a language communication relationship between patients who are native speakers of isiZulu language and non-isiZulu-speaking medical students. This study intends to generate new knowledge on the isiZulu translation process of medical content by addressing the problem of translating English medical content into the isiZulu language. Specifically, it relates to medical terminology that is non-existent in isiZulu. The main objectives of this study are to review language policies on the use of isiZulu in a medical context, to explore the isiZulu translation process of medical content to improve clinical communication in a clinical setting and to understand the influence of social aspects during the translation process. The study is based on two theoretical frameworks: Nord’s Functionalist theories (1992) and Vinay and Darbelnet’s translation approach (1995). This is a textual study; thus, it uses textual analysis of information from the ongoing UKZN medical school project of medical translated content. This study reflects on the translator's challenges and process when translating medical content from English into isiZulu. Moreover, it reflects on how the translator employs theories to guide the translation process. The study suggests that the isiZulu translation process of medical content for a communicative context is influenced by the social factors attached to language use and the differences in the grammatical nature of writing the languages involved in translation. The steps undertaken in the study highlight that the value of the isiZulu language to AmaZulu impacts the value of isiZulu and how isiZulu is used for communication purposes. The isiZulu language semantically dictates that certain terms should be avoided because of the derogatory status they carry on their social use, which affects the choice of terms during translation.
Exploring gamification within the teaching and learning of isiZulu first additional language: A case study on the use of Kahoot to motivate young learners.
(2023) Chiliza, Noluthando Noxolo.; Gokool, Roshni.
Traditional methods of second language learning, especially in the case of isiZulu as a First Additional Language (FAL), have often been analysed for their tedious and grammar-focused nature. These traditional methods can lead to a loss of learner commitment and inspiration. The outcome of this research study suggests that learners become disinterested due to the outdated and uninspiring teaching methods used for African languages like isiZulu. Therefore, this study seeks to explore the integration of Kahoot as an advanced instrument within the isiZulu FAL classroom to advance a more engaging and collaborative learning environment. Kahoot!, a popular gamification platform, allows learners to participate with isiZulu FAL in a fun and encouraging manner. This method signifies a departure from traditional teaching methods, aiming to reignite learners' curiosity and excitement for the language. However, there is a lack of research investigating integrating technology and gamification into the teaching and learning of isiZulu FAL, making this study particularly significant and innovative. The research targets grades 4,5 and 6 learners, aiming to evaluate the influence of Kahoot! on their isiZulu FAL learning experience. Data collection for this study is facilitated using an online questionnaire via Google Forms, allowing for effective and appropriate data gathering. Additionally, classroom observations provided a constructive qualitative perception of the learners' interactions with Kahoot! and their overall learning experiences. Existing research has proven that gamification-based platforms like Kahoot! can effectively motivate learners and advance language learning outcomes. Kahoot! is an active and engaging tool for both teaching and assessment purposes. This study aimed to contribute to the existing understanding by investigating the benefits and challenges of applying Kahoot! within the isiZulu FAL classroom by leveraging these findings. Drawing on support from previous studies that have emphasised the language learning effectiveness of Kahoot!, this research endeavours to offer perceptions and suggestions for the improved integration of Kahoot! into the isiZulu FAL curriculum. The study seeks to investigate the perception of Kahoot! as an instrumental resource for educators and learners alike, encouraging effective language learning within the isiZulu FAL context.