Showing items 1 - 20 of 99

Removal of sulphates from aluminium powder coating effluent using basic oxygen furnace slag and granulated blast furnace slag

- Vessal, Ali

The effectiveness of solar water heating geysers in South Africa : a review

- Thobejane, Jackson S., Masekameni, Daniel M., Rathebe, Phoka C., Mgwambani, Shalala L.

The investigation of the exposure time effects with pressure in the atomic layer deposition process over micro-trench surface

- Olufunsho, Oladipo Olotu, Coetzee, Rigardt Alfred Maarten, Jen, Tien-Chien, Olubambi, Peter Apata

  • Authors: Olufunsho, Oladipo Olotu , Coetzee, Rigardt Alfred Maarten , Jen, Tien-Chien , Olubambi, Peter Apata
  • Date: 2019
  • Subjects: Atomic layer deposition , Computational fluid dynamic , Exposure time
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/398293 , uj:33149 , Citation: Olufunsho, O.O. et al. 2019. The investigation of the exposure time effects with pressure in the atomic layer deposition process over micro-trench surface.
  • Description: Abstract: Tremendous interest has been drawn towards the atomic layer deposition (ALD) as an ultrathin film deposition technique to deposit conformal quality films in the micro-semiconductor industry. However, a further grasp of the ALD process is mandatory to increase the probability of the industry in achieving the necessary improvement which can have a substantial impact on device performance. However, little has been done to investigate the specific effects of the operation pressure on the mechanistic, species transport and reaction rates. Moreover, the effects of these prior properties due to the change of pressure on a complex micro-trench substrate have not been studied yet. Hence, this study focuses on numerically investigating the effect between one and 10 torr operating pressure in the ALD process using the computational fluid dynamic approach. A two-dimensional numerical simulation of the Al2O3 ALD thin film fabrication process over a surface with micro-trenches on a substrate is studied. Trimethyl-Aluminium and Ozone were utilized as the metal and oxidation source reactants. To assist the precursor reaction process a 2.5 second exposure time is added within the ALD sequence. The findings illustrated the fluid flow velocity, mass fraction, and growth of the thin-film process. The evaluations unveil close comparison to literature.
  • Full Text:

A comparative assessment of the structural, elastic and electronic properties of Nb3Pt and NbPt3 phases through firstprinciples study

- Fono-Tamo, R.S., Tien-Chien, Jen, Bhila, O.

A comparison of voltage stability assessment techniques in a power system

- Adebayo, I.G., Sun, Y.

  • Authors: Adebayo, I.G. , Sun, Y.
  • Date: 2018
  • Subjects: Power flow , Voltage collapse , Voltage stability
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/290646 , uj:31556 , Citation: Adebayo, I.G. & Sun, Y. 2018. A comparison of voltage stability assessment techniques in a power system.
  • Description: Abstract: Voltage stability analysis has of recent been a growing concern to power system utilities due to several incidence of blackouts that occurred lately in some part of the globe. This paper discusses some existing voltage stability techniques such as L-Index, Voltage Collapse Proximity Index (VCPI) and modal analysis of the reduced Jacobian. A comparative analysis of these techniques is also presented. The total computational time taken by each approach to attain a solution is also estimated in this work. The effectiveness of all the approaches is tested on the IEEE 14-bus power system. Simulation results obtained show that the use of modal analysis in the study of voltage stability in a power system will be of advantage compared with other techniques as it saves time and require less computational efforts.
  • Full Text:

A framework for effective management of water and sewer infrastructure

- Mawasha, Oarabile, Botha, Barend

  • Authors: Mawasha, Oarabile , Botha, Barend
  • Date: 2018
  • Subjects: Model Based Systems Engineering , MBSE , Water and sewer
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/289555 , uj:31418 , Citation: Mawasha, O. & Botha, B. 2018. A framework for effective management of water and sewer infrastructure.
  • Description: Abstract: From a municipal operational and maintenance perspective water and sewer infrastructure systems are complex systems with numerous components leading to recurring water pipe bursts and sewer blockages. This prompted the study to assess, analyze and quantify the characteristics of factors that compromise water distribution and sewer services reliability around Johannesburg (used as a case study). The aim of the study was firstly to investigate water and sewer infrastructure challenges by researching the relationship between operations, maintenance, design and construction. To develop a short-term framework for improving the day to day operations process based on data highlighting common failures. The common trend found in the literature case studies is the use of a water audit as a basis for assessing bursts, blockages, leaks and water losses. The water audit approach enables researchers to discover patterns in big data without formulating hypotheses by using a grading system (Lycett, A., 2013).This study considered various methods of managing water and sewer systems, developing a framework for addressing various types of infrastructure failures related to water and sewer. The study fills a gap by supporting effective project management of water leaks and sewer blockages by implementing quality management systems during construction to prevent recurring burst/blockages and post construction (maintenance plan linked to operations and complaint loggings from residents). In order to simplify understanding a Model Based Systems Engineering (MBSE) approach was used to develop and present a proposed framework. Failure Modes and Effects Analysis (FMEA) was used as a method to identify potential failures of a design, construction operations, maintenance, product and process identified. The FMEA was used as a continuation from the data to create the Framework The initial study focused on developing a short-term framework for improving the day to day operations process based on data findings. This is then to be escalated into a longer term framework over time.
  • Full Text:

A framework for improving centrifugal pump reliability and availability in air separation plants : a comparative case study

- Mphosa, Ibo, Botha, Barend

  • Authors: Mphosa, Ibo , Botha, Barend
  • Date: 2018
  • Subjects: Asset , Maintenance , Reliability
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/289563 , uj:31419 , Citation: Mphosa, I. & Botha, B. 2018. A framework for improving centrifugal pump reliability and availability in air separation plants : a comparative case study.
  • Description: Abstract: Although many different maintenance programmes exists in the current industrial domain, unintended downtime due to failures of centrifugal pumps remains a major source of downtime in air separation plants. This phenomenon is investigated here in the context of the implementation of reliability centred maintenance (RCM) framework in air separation environment. The main objectives of this study are to investigate centrifugal pump reliability problems in air separation plants and to identify the factors that lead to success or failure of RCM frameworks. Two case studies (plants) in the same organisation were selected for this research and the case study research methodology was used to investigate the outlined problem. It was found that effective two-way communication or lack thereof between the plant personnel and the Reliability Engineers affects knowledge sharing and quality of pump strategies. In this research an updated RCM framework and an asset strategy model provides the clarity and quality of communication that is required to improve centrifugal pump reliability. An updated framework was proposed based upon the findings of this research as a way to improve centrifugal pump reliability and availability in air separation plants.
  • Full Text:

A novel weighted vehicular network clustering scheme

- Chyne, Phidahunlang, Kandar, Debdatta, Paul, Babu Sena

A review of research on lightning protection for photovoltaic systems

- Holland, I., Doorsamy, W., Nixon, K.

A three-way partnership model of tourism graduate employability

- Wakelin-Theron, N., Ukpere, W.I., Spowart, J.

  • Authors: Wakelin-Theron, N. , Ukpere, W.I. , Spowart, J.
  • Date: 2018
  • Subjects: Employability , Tourism industry , Higher education
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://ujcontent.uj.ac.za8080/10210/382472 , http://hdl.handle.net/10210/290714 , uj:31564 , Citation: Wakelin-Theron, N., Ukpere, W.I. & Spowart, J. 2018. A three-way partnership model of tourism graduate employability.
  • Description: Abstract: The aim of this paper presentation is to show the employability of tourism graduates, using a three-way perspective. The concept of employability differs depending on the context, as well as the views of the people making employment decisions and those seeking employment. Graduates are not always employable, because they lack certain knowledge, skills, employability attributes, and practical work experience. Therefore, it has become imperative to ensure an adequate level of preparedness of tourism graduates, including their employability attributes, to enhance their chances of securing and sustaining employment in the tourism industry. The researcher adopted a sequential explanatory mixed method, which entailed combining quantitative and qualitative methods. The researcher conducted a quantitative survey on a purposive sample of 561 managers, supervisors and owners within the tourism industry and tourism graduates working in the tourism industry. The researcher used means, standard deviations, exploratory factor analysis and independent t-test. The qualitative research approach was applied to investigate graduate employability more in-depth. A total of twelve interviews were conducted with three academics within higher education institutions (HEIs) that offer a tourism qualification, three graduates working within the industry and three experts within the tourism industry. The researcher found a significant relationship between the professional skills, personality traits, knowledge skills and operation skill within the tourism industry. The researcher constructed a model to enhance graduate employability through a three-way perspective within the tourism industry. The model links all three partners the tourism graduate, tourism industry and Higher education institutions) that play a key role in the industry regarding the transfer of knowledge, skills and other employability attributes. The originality of this paper is that it constructed a model for the tourism industry to enhance graduate employability that links three partners, and creates further constructive debate.
  • Full Text:

Adsorption of BTEX compounds from water using green-synthesized iron nanoparticles

- Fayemiwo, O.M., Daramola, M.O., Moothi, K.

An analysis of the coverage of astronomy news in South African newspapers

- Sondlo, Aviwe

  • Authors: Sondlo, Aviwe
  • Date: 2018
  • Subjects: Astronomy Education , Online newspaper , Framing Theory
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/290681 , uj:31560 , Citation:
  • Description: Abstract: The 21st century is close to two‐decades‐old and there is a growing concern that South African media needs to improve their science news coverage to conscientise citizens with scientific literacy i.e. their knowledge about science, and the environment. This will assist in developing active citizens in a world that is dominated by complicated scientific and technological advances. The concern about how the media in particular newspapers portray science news is growing, since there is a belief that newspapers can play a pivotal role in educating the citizens. Newspapers can play a role when teaching science are regarded as a medium that can heighten students’ knowledge, enhance vocabulary skills and encourage a positive attitude towards learning. The aim of this study was to provide an overview of how online newspapers portray astronomy news in terms of framing and tone. The study is underpinned by framing theory, which suggests that presentation can influence the choices people make. A mixed method approach was employed since it combines both qualitative and quantitative methods to deal with different questions of the study. An instrument to collect data was not required, the data was available on the internet. I retrieved the newspapers from the internet and samples were drawn from two online newspapers, the Mail & Guardian and News24 from 1 January 2012 to 31 July 2015. The Nisbet framework and a modified story analysis form were used to analyse data. The quantitative results indicates that the coverage of astronomy news is still very limited in South Africa media based on the newspapers analysed. The finding shows that 82% of the analysed Mail & Guardian newspapers were general news, whereas only 76% of News24 stories were general news.
  • Full Text:

An approach to convergence between LTE and DSRC

- Jyrwa, Raymond Star, Kandar, Debdatta, Paul, Babu Sena

BPSK-OFDM versus QFSK-OFDM in combating the effects of narrowband interference and impulsive noise in power line communication

- Bolaji, Abiola G., Shongwe, Thokozani

Channel frequency response for a low voltage indoor cable up to 1GHz

- De Beer, A.S, Sheri, A., Ferreira, Hendrik C., Han Vinck, A.J.

  • Authors: De Beer, A.S , Sheri, A. , Ferreira, Hendrik C. , Han Vinck, A.J.
  • Date: 2018
  • Subjects: CFR , Low Voltage Cable , Contactless PLC
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/290470 , uj:31534 , Citation: De Beer, A.S. et al. 2018. Channel frequency response for a low voltage indoor cable up to 1GHz.
  • Description: Abstract: The Channel Frequency Response (CFR) is essential in the understanding and specification of Power Line Communications (PLC) equipment. In this paper a 10m indoor low voltage Flat Twin and Earth power cable is characterized up to 1GHz. This is higher in frequency than existing PLC specifications. This is done because the effect of frequencies in the upper VHF and lower UHF bands on PLC is largely unknown. Measurements and simulation are used to show that at higher frequencies, the traditional transmission line models of wave propagation on a power line are no longer valid. Classic attenuation models do not predict the correct CFR above typically 250MHz for a 10m cable. This effect is explained in terms of electromagnetic radiation from the cable. After 500MHz it is speculated that the line becomes a waveguide. These transmission modes have important implications for UHF PLC, either directly (connected cable) or when used in contactless mode where the power line is used as antenna.
  • Full Text:

Characterization of corrosion behavior of laser beam formed titanium alloy

- Akinlabi, S.A., Mashinini, M.P., Fatoba, S.O., Abima, C.S.

  • Authors: Akinlabi, S.A. , Mashinini, M.P. , Fatoba, S.O. , Abima, C.S.
  • Date: 2018
  • Subjects: Titanium Alloy , Corrosion Behaviour , Laser Beam Forming
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/290953 , uj:31594 , Citation: Akinlabi, S.A. et al. 2018. Characterization of corrosion behavior of laser beam formed titanium alloy.
  • Description: Abstract: The application of Titanium and its alloys are found in various industries such as Aerospace, Human implant, Automotive, Chemical processing, Geothermal, and Armoury etc. The unique properties of Titanium have made it immune to all forms of environmental attacks such as the urban pollution, marine and industrial. However, It is believed that all manufacturing processes often influences the materials and mechanical properties of the processed material.. This paper reports on the corrosion behaviour of Laser Beam Formed Titanium Alloy. Titanium sheets were laser formed using three constant parameters (laser power of 0.8kW, the beam diameter of 12 mm and scan speed of 0.03m/min) and varied paramter which is the number of scans – 3, 5 and 7. The corrosion behaviour was after that investigated in a 3.5% NaCl solution using the Potentiodynamic Polarization technique. The Potentiodynamic polarization curves were measured at a scan rate of 2mV/s starting from 1000.0mV concerning OCP to 1100mV. The result revealed that the parent material had the most significant resistance to corrosion and the lowest corrosion rate per year. While for the Laser formed Titanium sheets, it was observed that as the number of scans increases the resistance to pitting was increased. However, the Titanium sheets samples formed at seven and five laser scans developed microcracks on the surface of the samples even though the resistance to corrosion is improved with the two sets of samples. These defects render the laser formed titanium sheets undesirable for intended applications.
  • Full Text:

Climate sensitivity and snow-based tourism in Africa : an investigation of Tripadvisor review on Afriski, Lesotho

- Stockigt, L., Hoogendoorn, G., Fitchett, J.M., Saarinen, J.

Collaboration between LAMs in South Africa : a digitisation skills sharing initiative

- Mabe, Kagiso, Potgieter, Andrea

  • Authors: Mabe, Kagiso , Potgieter, Andrea
  • Date: 2018
  • Subjects: Libraries , Archives , Museums
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/289407 , uj:31400 , Citation: Mabe, K. & Potgieter, A. 2018. Collaboration between LAMs in South Africa : a digitisation skills sharing initiative.
  • Description: Abstract: The aim of this study was to determine the possible benefits if libraries, archives and museums (LAMs) in South Africa were to collaborate on digitisation efforts in terms of sharing skills and training. The following research question was formulated: What are the possible benefits for South African LAMs should they collaborate in terms of sharing skills and training, for digitisation purposes? The study thus addressed the collaboration between LAMs for digitisation purposes, in the context of the South African LAM landscape. A mono-method qualitative study was undertaken to investigate the main objective, that is, if collaboration could help LAMs deal with the challenges they face, in terms of skills, when digitising their collections. The objectives were addressed by a literature review and by conducting nonstandardised, semi-structured interviews with 21 interviewees at different LAMs. It was concluded that collaboration could indeed appreciably alleviate problems related to digitisation, the most prominent being the lack of skilled digitisation employees. It was found that many of the institutions employed low-level skilled workers or workers who were learning on the job. In determining the relevance of the research, it was important to find out whether or not LAMs in South Africa were open to collaboration and responses to this question were positive. It can thus be concluded that the results of this study can be used to motivate and push for collaborative partnerships for the purpose of digitisation between South African LAMs.
  • Full Text:

Computation of dust particle alignment for evaluation of microwave cross polarization

- Musa, Abdulwaheed, Paul, B.S.

  • Authors: Musa, Abdulwaheed , Paul, B.S.
  • Date: 2018
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/289886 , uj:31462 , Citation: Musa, A. & Paul, B.S. 2018. Computation of dust particle alignment for evaluation of microwave cross polarization.
  • Description: Abstract: Dual orthogonal polarization is a method of optimal conservation of frequency spectrum which has received researchers’ attention. The orthogonal polarization, however, is often subjected to the amount of discrimination obtainable in the dual channels. Investigation has shown that apart from the shape of falling dust particles, microwave cross polarization occurs because of dust particles alignment. This paper investigates and computes dust particle alignment which are inputs to cross polarization discrimination. Relevant forces influencing the particle alignment such as inertial torques and turbulence shear have also been calculated. The result shows how the forces affect the particle alignment, even as the torques dominating the alignment of certain dust particle sizes have also been established.
  • Full Text:

Constrained bending and straightening - a proposed method for severe plastic deformation of metals

- Mwita, W.M., Akinlabi, Esther Titilayo, Sanusi, K.O.

  • Authors: Mwita, W.M. , Akinlabi, Esther Titilayo , Sanusi, K.O.
  • Date: 2018
  • Language: English
  • Type: Conference proceeding
  • Identifier: http://hdl.handle.net/10210/291184 , uj:31616 , Citation: Mwita, W.M., Akinlabi, E.T. & Sanusi, K.O. 2018. Constrained bending and straightening - a proposed method for severe plastic deformation of metals.
  • Description: Abstract: The use of severe plastic deformation (SPD) technology to process ultra-fine/nano grains metals with enhanced desired properties for structural and biomedical applications have shown good results. However, SPD technology is still limited to discrete processes, small size samples with inhomogeneous strain. This paper proposes a new method for severe plastic deformation of metals known as constrained bending and straightening (CBS). The method is aimed to provide continuous production of ultra-fine/nano grains metals with improved strain homogeneity. The CBS process analytical model and its working principle are presented, a constitutive relation of feed length, bend roller diameter, effective strain and tensile strength is established. Results show that the magnitude and homogeneity of induced effective strain and tensile strength increase with the decrease of both feed length and bending roller diameter. Effective strain increased by 200% from 6mm to 2mm feed lengths. At 2mm feed length, tensile stress increased from 1223.8 MPa at 1 pass to 1302.5 MPa at 4 pass. Results from this study promise that CBS technique is potential to be adapted for continuous SPD of bulky length metal sheets with enhanced homogeneous properties.
  • Full Text:
  • Disclaimer
  • Privacy
  • Copyright
  • Contact