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Influence of anionic surfactants on the stability of multi-walled carbon nanotubes-based nanofluid
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Assessing market risk in BRICS and Oil Markets : an application of markov switching and vine copula
Get PDFAbstract: This paper investigates the dynamic tail dependence risk between BRICS economies and the world energy market, in the context of the COVID-19 financial crisis of 2020, in order to determine optimal investment decisions based on risk metrics. For this purpose, we employ a combination of novel statistical techniques, including Vector Autoregressive (VAR), Markov-switching GJR-GARCH, and vine copula methods. Using a data set consisting of daily stock and world crude oil prices, we find evidence of a structure break in the volatility process, consisting of high and low persistence volatility processes, with a high persistence in the probabilities of transition between lower and higher volatility regimes, as well as the presence of leverage effects. Furthermore, our results based on the C-vine copula confirm the existence of two types of tail dependence: symmetric tail dependence between South Africa and China, South Africa and Russia, and South Africa and India, and asymmetric lower tail dependence between South Africa and Brazil, and South Africa and crude oil. For the purpose of diversification in these markets, we formulate an asset allocation problem using raw returns, MS GARCH returns, and C-vine and R-vine copula-based returns, and optimize it using a Particle Swarm optimization algorithm with a rebalancing strategy. The results demonstrate an inverse relationship between the risk contribution and asset allocation of South Africa and the crude oil market, supporting the existence of a lower tail dependence between them. This suggests that, when South African stocks are in distress, investors tend to shift their holdings in the oil market. Similar results are found between Russia and crude oil, as well as Brazil and crude oil. In the symmetric tail, South African asset allocation is found to have a well-diversified relationship with that of China, Russia, and India, suggesting that these three markets might be good investment destinations when things are not good in South Africa, and vice versa
Evaluating occupational health and safety management strategy success factors for small-scale contractors in Zambia
Get PDFAbstract: Small-scale contractors (SSCs) require management strategies in implementing occupational health and safety (OH&S) performance at projects to reduce accidents, injuries, fatalities and diseases. Management strategy success factors have been acknowledged to be of great benefit in improving in OH&S performance. Hence, the study sought to assess the management strategy success factors for the improvement of OH&S performance by SSCs in Zambia’s electricity industry. Using quantitative methods, data was collected using a survey questionnaire from 246 respondents representing firm owners, managers, project managers and OH&S representatives at electricity industry projects at 70.3% response rate. Descriptive and inferential statistics were adopted as methods of data analysis using exploratory factor analysis. After analysis, the success factors were clustered into three construct categories within OH&S performance namely, compliance and workplace processes, policy and human resource development, and leadership and structure significant values ranging from 0.513 to 0.972. The independent reliability was tested using the Cronbach Alpha coefficient. The study exposed management strategy success factors are well recognised by most SSCs and contributed to the body of knowledge in this mastery by introducing three success factors for OH&S performance. It is recommended that these factors be adopted and considered to improve OH&S performance management by SSCs in the electricity industry in Zambia
Transformation of the private offshore wealth management service industry in the emerging economy
Get PDFAbstract: Dollarisation in emerging economies of Southern Africa like Zambia and Zimbabwe, led High-Income Earning Individuals (HIEI) to invest offshore as an investment diversification strategy. The turbulent past experiences influenced African HIEI behavior in relation to their wealth management approaches. HIEI started looking for ways to protect its financial assets against future political and economic volatilities. The purpose of this study was to equip academics and the wider commercial fraternity with practical and strategic knowledge of the emerging markets’ offshore wealth management services industry. This would assist emerging markets to regulate HIEI markets, boost capital flow, fight tax evasion to allow banks to assist, help governments protect pensions, promote transparency in investments and avoid negative effects of dollarisation. Data were collected from 81 participants including HIEIs with offshore investments, those individuals without, financial advisors, and the Securities Exchange Commission (the industry regulator). The study used a qualitative approach in its methodology using questionnaires, interviews, and a computer-aided system for data analysis. We found that HIEI feels their wealth is under attack and looks towards offshore investing as a refuge. We identified the desperate urge of African HIEIs to secure their wealth as the main influence driving the offshore investing phenomenon
Occupational health and safety factors influencing absenteeism among construction workers in Johannesburg, South Africa
Get PDFAbstract: Background Failure to report for scheduled work among construction workers has always been a major workplace challenge and concern in the construction industry. Unearthing factors that influenced non-attendance in this labour-intensive industry was prioritised in this research, conducted among skilled, semi-skilled, and unskilled employees in small and medium construction companies in Johannesburg. Objective: The study intended to determine an association between occupational health and safety (OHS) factors and absenteeism among construction workers. Methods: A cross-sectional design was adopted to determine the prevalence of exposure and the possible health outcomes for comparative analysis. Research participants were selected using a simple random sampling technique. The calculated sample size of 500 participants was determined using Epi InfoTM 7.2 statistical software. Data was analysed using the IBM SPSSTM Statistics version 26. Logistic regressions were used to analyse data...M.A. (Public Health
The effect of CO2 loading on the properties of normal concrete vs fly ash concrete
Get PDFAbstract: Purpose – There is an increase in greenhouse gasses and global climate change is frequently reported on. What can be done? Certainly to try and reduce the carbon footprint, which is not a new topic, by encouraging applications and activities for concrete during its lifetime (Portland Cement Association, 2019). This study focuses on introducing CO2 to normal and fly ash concrete and thus investigating the effect on the carbon footprint of the samples and the effectiveness of the CO2 introduction methods, namely carbonated water addition during the mixing process and by means of an infusion pipe directly into the concrete when the samples are casted and have been casted. Design/methodology/approach – The feasibility of carbon dioxide storage within concrete is determined by investigating the effects of introduced carbon dioxide into concrete samples and the effectiveness of the concrete at storing carbon dioxide. The concrete was mixed in a 1:3:3 ratio for the OPC or blended 52.5R cement:sand:stone (22mm) with a 28 day strength of 50MPa. Samples were also prepared containing low grade fly ash cement contents ranging from 15 to 60%. CO2 was introduced to the concrete via carbonated mixing water and an infusion pipe system directly to the hardening concrete cubes. 16g CO2 bicycle carbon dioxide inflators and valve system were used to infuse the concrete over a period of a week until the canister was emptied with valve release on the lowest setting. A compression test was carried out to determine the strength of the concrete cubes with, and without, the introduction of carbon dioxide. Results were also obtained using a Scanning Electron Microscope (SEM) and energy dispersive x-ray spectrometer (EDS) to determine how the carbon dioxide changed the microscopic composition and chemical composition of the concrete. A microcontroller with carbon dioxide sensors was used to gather carbon dioxide emission data for a period of 3 months. Findings - The compressive strength tests show by introducing carbon dioxide to the concrete, the compressive strength has increased by as much as 13.86% as expected from the literature. Furthermore, by infusing carbon dioxide with the fly ash blended cement, will give a higher strength compared to the control with ordinary portland cement. This correlates to an overall reduction in cost for the structure. The optimal fly ash content for the control with minimal strength degradation is 30%. Where the optimal fly ash content for the concrete with carbon dioxide stored within, is 45%. The SEM analysis showed the concrete with sequestered carbon dioxide has significantly more C-S-H gel formation, thus the strength increase. Furthermore, the carbon dioxide emission test showed the concrete with infused carbon dioxide stores carbon dioxide more efficiently compared to the control sample. With the data showing the infused sample releases 11.19% less carbon dioxide compared to the control sample. However, the carbonated water sample releases 20.9% more carbon dioxide when compared to the control sample. Thus the introduction of carbon dioxide by means of infusion is more effective. Originality/value - This is a practical pilot investigation of carbon dioxide introduction via two methods, one being infusion of CO2 into normal concrete and fly ash concrete and two, mixing normal and fly ash concrete with carbonated water. These results show, cheaper cement can be used to achieve equivalent or better strength. This can help in the reduction of the construction industry’s carbon footprint
Assessment of localized seasonal precipitation variability in the upper middle catchment of the Olifants River basin
Get PDFAbstract: This study used the Soil and Water Assessment Tool (SWAT) model together with regional climate downscaled (RCD) data from the CORDEX (Africa project), to assess the local seasonal precipitation variability in the upper middle catchment (UMC) of the Olifants River basin. The study results, based on two scenarios (RCP4.5 and RCP8.5), showed a wider monthly and seasonal variability of precipitation. The study also indicated a strong decreasing trend of east-to-west direction of spatial precipitation, with most precipitation concentrated in the eastern part of the study area. Within the western part of the UMC, we also noted another decreasing trend of precipitation from south-tonorth with northern areas of the study area receiving the least amount of precipitation. This study has also revealed a considerable general reduction of future seasonal precipitation especially in the mid-term period (2021–2050). The general reduction in future seasonal precipitation, combined with the increasing temperatures in the area, may exacerbate the drought conditions and reduction in streamflow of the main river (Olifants) and its tributaries, consequently having a negative impact on the economic activities in the basin
Mapping past human land use using archaeological data : a new classification for global land use synthesis and data harmonization
Get PDFAbstract: In the 12,000 years preceding the Industrial Revolution, human activities led to significant changes in land cover, plant and animal distributions, surface hydrology, and biochemical cycles. Earth system models suggest that this anthropogenic land cover change influenced regional and global climate. However, the representation of past land use in earth system models is currently oversimplified. As a result, there are large uncertainties in the current understanding of the past and current state of the earth system. In order to improve representation of the variety and scale of impacts that past land use had on the earth system, a global effort is underway to aggregate and synthesize archaeological and historical evidence of land use systems. Here we present a simple, hierarchical classification of land use systems designed to be used with archaeological and historical data at a global scale and a schema of codes that identify land use practices common to a range of systems, both implemented in a geospatial database. The classification scheme and database resulted from an extensive process of consultation with researchers worldwide. Our scheme is designed to deliver consistent, empirically robust data for the improvement of land use models, while simultaneously allowing for a comparative, detailed mapping of land use relevant to the needs of historical scholars. To illustrate the benefits of the classification scheme and methods for mapping historical land use, we apply it to Mesopotamia and Arabia at 6 kya (c. 4000 BCE). The scheme will be used to describe land use by the Past Global Changes (PAGES) LandCover6k working group, an international project comprised of archaeologists,..
From ‘other worlds’ and ‘multiple ontologies’ to ‘a methodological project that poses ontological questions to solve epistemological problems’. What happened to Thinking Through Things?
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Off the beaten track tourism within Johannesburg inner city
Get PDFAbstract: City tourism as a travel segment is one of the major components of global tourism and cities are recognised as major tourism destinations. Tourism in major cities usually has occurred around ‘tourism districts’ in or close to the inner areas of cities. Over the past two decades in many leading tourism cities the character of inner city tourism has been changing. Researchers have recognised what has been termed a ‘new urban tourism’ which has been associated with new and emerging trends that urban tourism is branching out into which attracts niche travellers. These niche travellers are more concerned with travelling for experiences, visiting places that are far from the traditional routes and travelling in smaller groups with a goal of practicing tourism that has less environmental impacts on the surroundings. This sort of niche travel has led to the development of ‘off the beaten track tourism’ which describes a form of travel that is concerned with exploring the inner-cities and finding places and attractions often situated in marginalised neighbourhoods that are less appealing to the traditional urban tourists. Through off the beaten track tourism, new urban tourists want to explore places of interests on their own terms and essentially be part of the everyday fabric without being necessarily identified to as a tourist. Arguably, off the beaten track tourism has attracted much attention internationally in terms of research interest in Europe and North America. In the cities of the global South there is limited scholarship. This research study seeks to contribute to the current literature centred around off the beaten track tourism in cities in South Africa. This research is concentrated on understanding off the beaten track tourism from the perspective of tour operators who host tours within inner city Johannesburg. This was achieved through interviewing 10 tour operators that host various tours and the research also investigated the perspective of 127 tourists before and after they participated in the tours. The research is concluded with the notion that off the beaten track tourism within inner city Johannesburg is growing and more places are being discovered which is helping to shift the perceptions of the inner city into a positive space.M.A
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