TEMM International Pty Ltd.

South Africa

TEMM International Pty Ltd.

South Africa
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Nell R.W.,North West University South Africa | Kleingeld M.,University of Pretoria | Kleingeld M.,TEMM International Pty Ltd. | Liebenberg L.,University of Pretoria | Liebenberg L.,TEMM International Pty Ltd.
Journal of the Southern African Institute of Mining and Metallurgy | Year: 2016

The need to nitride the interior of large machine housings, which are also pressure vessels, for use in a high-temperature gas reactor resulted in the development of a suitable new nitriding technique whereby the vessel interior is used as a process chamber while being heated in a conventional top-hat heat treatment furnace. However, this new concept introduced several mechanical design challenges, such as an extended-length fan shaft, a high-temperature bearing, and sealing flanges for operation under extremely high temperatures. A prototype nitriding plant was constructed and operated to verify the design. The different tunnels machined inside the forged vessel were nitrided evenly by measuring and balancing the gas flow through each tunnel. Test specimens placed at different positions in the housing were also nitrided during the process. The nitrided specimens were subjected to microhardness and layer thickness tests. Measured gas flow rates and other operational data confirmed the inverse proportionality between ammonia supply flow rate and measured crack ratio, as well as a crack ratio temperature dependence, typical of conventional gas nitriding processes. The design and operation of the nitriding plant were successful and a nitride layer thickness of 400 m and a hardness of approximately 1100 VHN were achieved. This proves that a large pressure vessel can be successfully nitrided using the vessel's interior as a process chamber. © The Southern African Institute of Mining and Metallurgy, 2016.

Legg M.,North West University South Africa | Legg M.,TEMM International Pty Ltd. | Mathews E.,North West University South Africa | Mathews E.,TEMM International Pty Ltd. | And 2 more authors.
Cardiovascular Journal of Africa | Year: 2012

A study was conducted into the development of a mitral and aortic heart valve replacement that caters for patients having suffered valve damage due to stenosis or rheumatic fever. The appeal of the valve is that it is constituted from a solid frame housing pericardial tissue leaflets, and allows the patient freedom from post-operative blood-thinning medication. The valve is designed to appeal to patients in developing areas of the world, as it features a clip-in mechanism to secure the valve assembly into the sewing ring, which is stitched in independently of the frame and leaflets. Re-operative valve replacement would then be made possible when the pericardial leaflets began to calcify. Novel aspects of the design added value to the science of heart valve replacements, through the use of sintered chrome cobalt in the valve components, the insights gained into mechanical testing of pericardium, and the patient benefits offered by the complete design. Further work is planned to fatigue test the assembly, undergo animal trials and make the valve available for commercial use.

Liebenberg L.,North West University South Africa | Liebenberg L.,TEMM International Pty Ltd | Velleman D.,North West University South Africa | Velleman D.,TEMM International Pty Ltd | And 2 more authors.
Journal of Energy in Southern Africa | Year: 2012

Once designed, mine compressed-air systems tend to operate at peak levels throughout the life of the mine, despite there being significant periods when this air quantity is not required. This is mainly due to lack of appropriate compressor controls. Consequently, such compressed-air systems are inefficient and wasteful. A compressed-air system at a South African gold mine was retrofitted with an automatic compressor control system featuring compressor cascading and pressure bandwidth control. The goal was to implement a simple demandside management (DSM) strategy to afford meaningful electrical energy savings. The automatic control strategy realised a saving of 1.25 MW (on a baseline of 7.22 MW) during Eskom's evening peak demand window. This represents a reduction of 17.3% in electrical power consumption during the evening peak period, and savings of nearly R2.9 million per year.

De Beer J.C.,University of Pretoria | Liebenberg L.,University of Pretoria | Liebenberg L.,TEMM International Pty Ltd
British Journal of Cancer | Year: 2014

Background: The risks for several cancer types are increased in people with diabetes. Hyperglycaemia, hyperinsulinaemia, inflammation and altered hormonal concentrations are common characteristics between the two diseases and can all be linked to hyperglycaemia. Methods: Here, we use glycated haemoglobin (HbA1c) as a biomarker for chronic hyperglycaemia. We explore whether cancer risk increases with HbA 1c, independent of diabetes, and, therefore, if risk is already increased below the diabetic HbA 1c range, by analysing data from current studies linking HbA 1c to risk of several cancer types. Results: The data reveal that chronic hyperglycaemia correlates with increased cancer risk for a number of cancers, except prostate cancer. Evidence is also provided that risk is already increased in the pre-diabetic and normal ranges for several cancers. Conclusions: These results merit urgent investigation into the risks and advantages of updating recommendations for stricter glycaemic control in diabetic and non-diabetic subjects, as this could help reduce the risk of cancer incidence and mortality.© 2014 Cancer Research UK. All rights reserved.

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