Showing items 1 - 20 of 36

Banking 3

- University of Johannesburg

Credit Control 1A

- University of Johannesburg

Biodiesel production over ZnO/TiO₂ catalyst : effect of co-solvent, temperature and reaction time

- Mahangani, Ndanganeni, Vunain, Ephraim, Meijboom, Reinout, Jalama, Kalala

  • Authors: Mahangani, Ndanganeni , Vunain, Ephraim , Meijboom, Reinout , Jalama, Kalala
  • Date: 2015-07-01
  • Subjects: Biodiesel , Hexane , Waste vegetable oils
  • Type: Article
  • Identifier: uj:5127 , ISBN 9789881404701 , http://hdl.handle.net/10210/14090
  • Description: The aim of this work was to produce biodiesel from waste vegetable oil over ZnO/TiO2 catalysts as well as investigating the effect of co-solvent (hexane), reaction temperature and time on waste vegetable oil conversion to biodiesel. Production of biodiesel from virgin oil is still a downfall in commercial processes due to high cost. Thus, the process of producing biodiesel from waste vegetable oil over a TiO2-supported ZnO catalyst was studied in the absence and the presence of hexane as co-solvent respectively. The conversion of waste vegetable oil was found to increase with temperature and reaction time. The highest conversion that has been achieved was 99.1% at a temperature of 200 °C after 15 min of reaction for the reaction using hexane as co-solvent. The use of hexane as co-solvent was found to increase the oil conversion at lower reaction temperature and no effect was observed at higher temperatures.
  • Full Text:

Characterization of functionally graded commercially pure titanium (CPTI) and titanium carbide (TiC) powders

- Akinlabi, Esther Titilayo, Akinlabi, Stephen A.

  • Authors: Akinlabi, Esther Titilayo , Akinlabi, Stephen A.
  • Date: 2015-07-01
  • Subjects: Functional graded materials , Laser metal deposition , Titanium , Titanium carbide
  • Type: Article
  • Identifier: uj:5136 , ISBN 9789881404701 , http://hdl.handle.net/10210/14102
  • Description: Functionally Graded Materials (FGM) are advanced materials fabricated using additive manufacturing techniques. It belongs to a class of advanced material characterization in which the properties of the material composition is varied. The resulting property of the composite is always different from the properties of the individual material employed in the formation of the composite. They are known to also exhibit good mechanical and chemical properties and as such, are used for different industrial applications. One of the techniques employed in the fabrication of FGMs is called Laser Metal Deposition (LMD) technique. It uses laser beam to melt powder material on a substrate forming a melt pool that solidifies upon cooling. This paper reports on the material characterization of functionally graded Titanium and Titanium Carbide (TiC) powders deposited on Titanium substrate by laser metal deposition approach. The formed deposits were fabricated by varying the processing parameters such as laser power, scanning speed and the powder flow rate. From the result obtained, the microstructures showed that the laser power has much influence on the grain growth of the material. In addition, with the SEM analysis of the microstructure since the percentages of the titanium and titanium carbide were varied, it was observed that the sharp boundaries of the Titanium Carbide were reduced greatly and this resulting effect can be attributed to the thermal effect of the laser. The microstructures further revealed that as the percentage of TiC decreases, it becomes more difficult to see the TiC as a different material in the composite, emphasizing this as one of the best characteristics of functionally graded materials, which is the elimination of sharp interfaces and layers. Furthermore, it was observed that the laser power has great influence on the evolving hardness of the material compared to the TiC content.
  • Full Text:

Effect of punch diameters on shear extrusion of 6063 aluminium alloy

- Erinosho, M. F., Ajiboye, J. S., Akinlabi, Esther Titilayo

  • Authors: Erinosho, M. F. , Ajiboye, J. S. , Akinlabi, Esther Titilayo
  • Date: 2015-07-01
  • Subjects: Aluminum alloys , Shear extrusion , Punch diameters
  • Type: Article
  • Identifier: uj:5121 , http://hdl.handle.net/10210/14079
  • Description: This paper reports the effect of punch diameters on the shear extrusion of 6063 Aluminium alloy. During the shear extrusion process, Aluminium billets of considerable diameter 30 mm and height 25 mm were inserted in a die hole and different punches of diameter 12 mm, 14 mm, 16 mm and 18 mm respectively were allowed to come in contact to perform the shear operation. The setup took place under a hydraulic press with maximum capacity of 600 kN. This work is aimed at studying the selection of the optimum punch diameter for shear extrusion using local groundnut oil as the lubricant. Different extrusion pressures were measured and the punch with a diameter of 18 mm gives the highest load of 77.7 kN while the punch with a diameter of 12 mm gives the lowest load of 51.2 kN. An indication shows that, an increase in the punch diameters led to an increase in the height of the extrudates and this in turn reduces the stress induced.
  • Full Text:

Influence of scanning speed and energy density on the evolving properties of laser deposited Ti6Al4V/Cu composites

- Erinosho, Mutiu F., Akinlabi, Esther Titilayo, Pityana, Sisa

  • Authors: Erinosho, Mutiu F. , Akinlabi, Esther Titilayo , Pityana, Sisa
  • Date: 2015-07-01
  • Subjects: Laser metal deposition , Microhardness , Titanium composites , Copper composites
  • Type: Article
  • Identifier: uj:5131 , ISBN 9789881404701 , http://hdl.handle.net/10210/14094
  • Description: Titanium is a light metal and finds application majorly in the aerospace and bio medicals. This paper presents the influence of scanning speed and energy density on the evolving microstructure and microhardness of laser deposited Ti6Al4V/Cu composites. The laser power, powder flow rates and gas flow rates were kept constant while varying the scanning speed. From the microscopic analysis, α acicular structures were found growing from the top of the cross section of the composite and broke into the β-phase and the grain boundary of the (α+β) phase, and found to disappear gradually as the scanning speed increases. Widmanstettan was also found in all the samples. Sample S21 of energy density 240 J/mm2 deposited with a laser power of 1200 W and a scanning speed of 5 mm/secs shows the highest hardness value of 541±20 HV0.5 while Sample S27 of energy density of 48 J/mm2 deposited with a laser power of 1200 W and a scanning speed of 25 mm/secs shows the lowest hardness value of 405±12 HV0.5. This was attributed to the Cu content added and plays a vital role in stabilizing and strengthening the β-phase.
  • Full Text:

Microstructural characterization of friction stir lap welds of aluminium incorporated with titanium carbide

- Abegunde, O. O., Akinlabi, Esther Titilayo, Madyira, D. M.

  • Authors: Abegunde, O. O. , Akinlabi, Esther Titilayo , Madyira, D. M.
  • Date: 2015-07-01
  • Subjects: Aluminium , Friction stir welding , Titanium carbide , Aluminum
  • Type: Article
  • Identifier: uj:5123 , ISBN 9789881404701 , http://hdl.handle.net/10210/14085
  • Description: In this research study, the characterization of the microstructure evolution of friction stir lap welds (FSLW) of Aluminium incorporated with Titanium Carbide powder to form Aluminium based composites is presented. The Titanium Carbide powder was infused at the weld interface to produce a composite. The FSLW were conducted on an Intelligent Stir Welding for Industry and Research (I-STIR) Process Development System (PDS). Different welding parameters were used for the welding process. Rotational speeds of 1600 rpm and 2000 rpm and transverse speeds of 100 mm/min, 200 mm/min and 300 mm/min were employed. The process parameters were carefully selected to represent a low, medium and high setting for the feed rates. The microstructural evolution of the samples were studied. Optical microscope and scanning electron microscopy (SEM) techniques were used to investigate the particle distribution of the welded samples. The results obtained revealed the influence of the welding parameters on the particle distribution of the welded samples. A homogenous mixture of the materials was observed at higher rotational speed of 2000 rpm.
  • Full Text:

Waste vegetable oils to biodiesel over Al₂O₃ –supported SnO₂ catalyst : effect of support pore size

- Zulu, Vusumuzi C., Vunain, Ephraim, Meijboom, Reinout, Jalama, Kalala

  • Authors: Zulu, Vusumuzi C. , Vunain, Ephraim , Meijboom, Reinout , Jalama, Kalala
  • Date: 2015-07-01
  • Subjects: Biodiesel , Waste vegetable oils
  • Type: Article
  • Identifier: uj:5132 , ISBN 9789881404701 , http://hdl.handle.net/10210/14098
  • Description: The main aim of this study was to investigate the catalytic properties of Al₂O₃-supported SnO₂ for the conversion of waste vegetable oil into biodiesel. The effect of support pore size on waste oil conversion was investigated at 100 and 200 °C by using α-alumina (with larger pore size) and γ-alumina (with smaller pore size) respectively as support for SnO₂. The effect of pore-size on conversion was found to depend on the operating temperature. At low temperature, i.e. 100 °C, higher conversion for waste vegetable oil was measured on SnO₂ catalyst supported on α-Al₂O₃ than the catalyst supported by γ-Al₂O₃. This effect became less significant at 200 °C. It was also observed that the oil conversion increased with an increase in reaction temperature and reaction time.
  • Full Text:

Humanitarian space and security of humanitarian workers : a review

- Bayode, Abiodun, Mbohwa, Charles, Akinlabi, Esther Titilayo

  • Authors: Bayode, Abiodun , Mbohwa, Charles , Akinlabi, Esther Titilayo
  • Date: 2015-03-18
  • Subjects: Humanitarian space , Humanitarian assistance - Security measures
  • Type: Article
  • Identifier: uj:5125 , ISBN 9789881925398 , http://hdl.handle.net/10210/14088
  • Description: Humanitarian crisis leave the affected people in need of water, health care, and shelter. In order to promptly and adequately respond to the overwhelming needs of the vulnerable people, both the local and the international community has formed several humanitarian organizations, charged with the responsibility of providing aid and assistance to people affected by crisis, irrespective of their geographical location. Humanitarian organizations require safe passage to carry out their operations; the concept of humanitarian space was developed to ensure this. While preserving humanitarian space in conflict zone is proving challenging to humanitarian organizations because of various factors, it is however clear that the security of aid workers is a major concerns for aid organizations working in areas experiencing social change or armed conflicts. The rates of kidnapping, injuries and deaths of aid workers seems be on the increase, requiring aid agencies to be more security conscious and adopt measures to save guard the lives of their employees. Some measures taken recently by humanitarian organizations include suspending aid when and where the security of their employees is under threat and in some cases withdrawing completely from such environment. Thus, affecting the ability of aid organizations to carry out their mandate and as a result, those who are in dire need of relief and assistance suffer. For there to be an improvement in aid delivery, warring parties should respect the sanctity of humanitarian space and the ethics governing humanitarianism. This paper therefore present a review of humanitarian space and the security of humanitarian aid workers.
  • Full Text:

Microstructure and mechanical properties of ultra-fine grained copper processed by equal channel angular pressing technique

- Sanusi, Kazeem Oladele., Afolabi, Ayo Samuel, Muzenda, Edison

A qualitative analysis of Sport Management interns’ perceptions of rotations in internships

- Surujlal, J., Serra, P.

  • Authors: Surujlal, J. , Serra, P.
  • Date: 2014
  • Subjects: Sport management , School-to-work transition - South Africa , Internship programs - South Africa , Sport Management interns
  • Type: Article
  • Identifier: http://ujcontent.uj.ac.za8080/10210/387177 , uj:5509 , http://hdl.handle.net/10210/13675
  • Description: The sport industry, which has evolved into a multi-billion rand industry, offers an increased number of complex and varied job opportunities. University Sport Management graduates are thus likely to face greater job demands in a highly competitive work environment. Rotations in Sport Management internships have been identified as an approach to prepare students for the job market. The purpose of this study was to ascertain the perceptions of Sport Management interns of rotations in internship. A qualitative case study research approach was used in the study. Eight semi-structured focus group interviews were conducted with Sport Management interns who completed their internship. The results of the study indicated that the positive experiences associated with the internship outweighed the negative experiences. Participants reported many benefits of rotations in internship. Among these were their experiences of different aspects of a sport organisation, exposure to different leadership styles, opportunity to apply their theoretical knowledge in the workplace, social issues in the workplace and development of different competencies. The findings also identified areas in which the internship experience could be strengthened. Given the great satisfaction experienced by interns, rotations in interns appear to be an ideal replacement to the traditional implementation of internship.
  • Full Text:

Common failures of Hadfield steel in application

- Bhero, S.W., Nyembe, B., Lentsoana, K.

Comparative analysis of the challenges of generic engineering logistics to humanitarian logistics in disaster response and relief support in South Africa

- Bayode, Abiodun, Mbohwa, Charles, Akinlabi, Esther Titilayo

  • Authors: Bayode, Abiodun , Mbohwa, Charles , Akinlabi, Esther Titilayo
  • Date: 2014
  • Subjects: Disaster management , Logistics management , Humanitarian response , Non-governmental organizations
  • Type: Article
  • Identifier: uj:4723 , ISSN 978-988-19252-0-6 , http://hdl.handle.net/10210/11548
  • Description: Logistics management has been extensively researched and implemented in the private sector, but gradually gaining traction in the humanitarian sector. Humanitarian organizations, particularly Non-Governmental Organizations (NGOs) are the primary vehicle through which donors channel their contributions but many of these organizations face logistic challenges in effectively getting relief materials to the intended users. The purpose of this paper is to identify the key challenges affecting aid agencies in South Africa. A comparative analysis of the challenges of generic engineering logistics to humanitarian logistics in disaster response and relief support system in South Africa was also conducted. The findings from the research survey shows that there is an awareness of the importance of humanitarian logistics in the sector, but the results also show that only half (50%) of the participants of the survey reported that they have a logistics professional employed in their organization. Furthermore, only 50% of the participants of the survey indicated that their organization has a preparedness plan in place in the event of an emergency. Other challenges identified are: lack of funds; difficulty to obtain real time information and poor knowledge management system. The study also suggests that learning and forging closer ties with private organizations is an effective means of overcoming some of the identified challenges. In comparison to the generic engineering logistics, the humanitarian sector is encouraged to benchmark their operations with similar private sector to improve their services.
  • Full Text:

Determination of the ductile to brittle transition temperature of Austempered ductile iron

- Bhero, Shepherd, Mathabathe, Maria

  • Authors: Bhero, Shepherd , Mathabathe, Maria
  • Date: 2014
  • Subjects: Alloys , Iron founding , DBTT of ADI , Low temperature engineering
  • Type: Article
  • Identifier: uj:5092 , http://hdl.handle.net/10210/13682
  • Description: Austempered ductile iron (ADI) is a relatively new material that is increasingly finding space in industrial application. ADI possesses a unique combination of hardness and toughness that is not typical of most ferrous materials, where an increase in strength is invariably accompanied by a decrease in toughness and vice versa. Although the superiority of ADI is well documented in literature, there is still widespread scepticism application because not all properties are well known. This paper aims to determine the ductile to brittle transition temperature (DBTT) of ADI in order to establish its suitability for cryogenic applications.
  • Full Text:

Electrical muscle stimulation (EMS) training of the hamstrings

- Lategan, Leon, Crafford, Kylie, Suliman, Farzana, Govender, Natrishka

  • Authors: Lategan, Leon , Crafford, Kylie , Suliman, Farzana , Govender, Natrishka
  • Date: 2014
  • Subjects: Electrical muscle stimulation , Hamstring strength training
  • Type: Article
  • Identifier: uj:5423 , http://hdl.handle.net/10210/11950
  • Description: The aim of this study was to investigate the effects of EMS training on hamstring muscle strength. The study utilised a quantitative experimental research design. The intervention was assessed using a Humac Norm 7000 Dynamometer. A Chattanooga Intelect Mobile Combo muscle stimulator was used for the 4-week EMS training based on the 10-50-10 or “Russian Protocol”. Descriptive statistics were performed and pre- to post-test changes were analized using dependant t-tests. Statistical significance was set at p≤0.05. Following 4-weeks’ EMS training there were statistically significant increases in both the PTQ and work performed during concentric isokinetic knee flexion at 60°/s. There was also a 21.4% increase in the H/Q ratio following the EMS training. Considering the present results and previous research conducted, both the quadriceps and hamstring muscles groups seem to be responsive to EMS strength training.
  • Full Text:

Failure of structure in East Africa with focus on the causes of failures in the construction phase

- Alinaitwe, Henry Mwanaki, Ekolu, Stephen

  • Authors: Alinaitwe, Henry Mwanaki , Ekolu, Stephen
  • Date: 2014
  • Subjects: Structural failures - East Africa , Reinforced concrete construction - East Africa , Construction industry - East Africa
  • Type: Book chapter
  • Identifier: uj:5035 , http://hdl.handle.net/10210/13555
  • Description: Despite the relatively well-established concrete practice in the East African region, there are frequent incidents of construction failures, resulting into heavy loss of lives and property. The main objective of this paper was to examine structures that have failed during the construction phase, in East Africa, since the start of the 21st century; identify and discuss the primary causes and sources of failures. A classic failure case of building collapse, herein referred to as BBJ building, has been used to examine the most important issues related to construction failures. Following the analysis of reports of technical investigations undertaken on the collapsed structure, it was found that failures in reinforced concrete (RC) structures during construction, result from five primary causes of: (1) poor materials and workmanship, (2) design and construction errors, (3) absence of professional supervision of site- works, (4) wrong implementation of construction methods, (5) neglect of design approval procedures. Secondary issues that are complicit to construction failures are:- attempts to severely minimize construction cost, neglect of inspection and monitoring by local authorities, influence peddling by proprietors. It is evident that construction failures can be minimized if the right procedures are followed in the design, construction and operation of the structures; a matter that is of interest to stakeholders of the Built Environment.
  • Full Text:

Media analysis of the 2010 FIFA World Cup using newspaper print

- Serra, P., Shaw, I.

  • Authors: Serra, P. , Shaw, I.
  • Date: 2014
  • Subjects: World Cup (Soccer) (2010 : South Africa) , Content analysis (Communication) , Media content analysis
  • Type: Article
  • Identifier: uj:5485 , http://hdl.handle.net/10210/13604
  • Description: Major sporting mega-events such as the 2002 FIFA World Cup in North Korea, 2006 FIFA World Cup in Germany and the 2010 FIFA World Cup in South Africa have shown to act as powerful tools for promoting nation-building. Drawing upon the body of knowledge of the sociology of sport and content analysis of media studies, this study focused on the mediated messages pertaining to the 2010 FIFA World Cup in selected South African newspapers. A quantitative survey in terms of frequency of articles (text) and the scope of quantitative photographic images was undertaken. Data were collected over eight-weeks which included the build-up, tournament and post tournament of the 2010 FIFA World Cup. A total of 1118 images and 2225 articles were analysed to determine the thematic themes behind stories, from which media formulation stems and the printed media material quantifiable in terms of coverage, thematic themes presented, photos and results printed. The findings revealed predominant images and narrations of success (n=192), nationhood (n=125) and Pan-Africanism (n=114) and were mediated mainly as large main feature articles in prominent sections of newspapers. The 2010 FIFA World Cup translated into significant political, social and cultural dynamics and influential messages of temporary euphoria and nation building.
  • Full Text:

Preparation and characterization of polypropylene carbonate bio-filler (eggshell powder) composite films

- Feng, Ye, Ashok, B., Madhukar, K., Zhang, Jinming, Zhang, Jun, Reddy, K. Obi, Rajulu, A. Varada

  • Authors: Feng, Ye , Ashok, B. , Madhukar, K. , Zhang, Jinming , Zhang, Jun , Reddy, K. Obi , Rajulu, A. Varada
  • Date: 2014
  • Subjects: Biocomposites , Eggshell powder , Fractographs , Polypropylene carbonate , Tensile properties , Thermal degradation
  • Type: Article
  • Identifier: uj:4815 , ISSN 1563-5341 , http://hdl.handle.net/10210/12256
  • Description: In recent years, biodegradable polymer composites have attracted considerable attention due to inadequate and depleting petroleum resources and to replace nonbiodegradable synthetic polymers posing environment problems. In the present work, biodegradable composites based on polypropylene carbonate (PPC)=eggshell powder (ESP) were prepared by the solution-casting method using chloroform as the solvent. Polypropylene carbonate was loaded with 1 to 5 wt% of eggshell powder (particle size<40 mm). Characterization of the composites was accomplished by Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and X-ray diffraction (XRD) analysis, and morphological studies were carried out by optical microscopy (OM) and scanning electronic microcopy (SEM). The tensile properties of the composite films were found to be higher than those of neat PPC matrix and increased with ESP content up to 4 wt.% and then decreased. This work offers an easy path to manufacture ecofriendly PPC=eggshell powder com- posite films with improved properties, and reducing, in some cases, the demand for petroleum-based plastics such as polyolefins.
  • Full Text:

Recycled-PET fibre based panels for building thermal insulation : environmental impact and improvement potential assessment for a greener production

- Ingrao, Carlo, Giudice, Agata Lo, Tricase, Caterina, Rana, Roberto, Mbohwa, Charles, Siracusa, Valentina

  • Authors: Ingrao, Carlo , Giudice, Agata Lo , Tricase, Caterina , Rana, Roberto , Mbohwa, Charles , Siracusa, Valentina
  • Date: 2014
  • Subjects: Life cycle assessment , Thermal insulation , Environmental sustainability , Recycled Polyethylene Terephthalate
  • Type: Article
  • Identifier: uj:4817 , ISSN 0048-9697 , http://hdl.handle.net/10210/12258
  • Description: A screening of Life Cycle Assessment for the evaluation of the damage arising from the production of 1 kg of recycled Polyethylene Terephthalate (RPET) fibre-based panel for building heat insulation was carried out according to the ISO 14040:2006 and 14044:2006. All data used were collected on site based on observations during site visits, review of documents and interviews with technical personnel and management. These data were processed by using SimaPro 7.3.3, accessing the Ecoinvent v.2.2 database and using the Impact 2002+ method. The study showed damage to be equal to 0.000299 points mostly due to the: 1) PET thermo-bonding fibre supply fromChina bymeans of a freight-equipped intercontinental aircraft; 2) production of bottle-grade granulate PET; 3) mediumvoltage electricity consumption during the manufacturing of RPET fibre panel. Itwas also highlighted that there were environmental benefits due to recycling through mainly avoiding significant emissions and reduced resource consumption. An improvement assessment was carried out to find solutions aimed at reducing the damage coming from the most impacting phases. Furthermore, the environmental impacts due to the production of the analysed RPET fibre-based panelwere compared to other materials with the same insulating function, such as polystyrene foam, rockwool and cork slab. Finally, the environmental benefits of the recycling of PET
  • Full Text:

Biomass and small hydro power potential in Zimbabwe

- Mbohwa, Charles

  • Authors: Mbohwa, Charles
  • Date: 2013
  • Subjects: Biomass , Hydroelectric power plants - Zimbabwe , Water-power - Zimbabwe
  • Type: Article
  • Identifier: uj:6168 , http://hdl.handle.net/10210/13775
  • Description: This paper investigates the potential for biomass and small hydro power in Zimbabwe to identify alternative and more sustainable power sources in Zimbabwe. It presents possible enabling framework that can guide decision making in new power development in the country. It informs policy makers, takers and implementers about the role renewable energy can take in complementing conventional power technologies in Zimbabwe. The methods uses are desk study, document reviews interview, data manipulation, assessment and analysis and identification of recommendations for hydro and biomass power in Zimbabwe. The findings show the following power potential levels: perennial rivers 50MW; sugar industry 210MW of power; wood industry waste combustion 150MW; urban solid waste 158.4MW, and biogas from 4 cities 316.8MW. Policy options and instruments to promote renewable power technologies are briefly discussed. Renewable Energy Technologies are found to be cost-competitive when compared to conventional energy sources and can assist to provide power security.
  • Full Text:
  • Disclaimer
  • Privacy
  • Copyright
  • Contact