TEMM Intl. Pty Ltd.

South Africa

TEMM Intl. Pty Ltd.

South Africa

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Van Heerden A.S.J.,University of Pretoria | Lidbetter R.,North West University South Africa | Lidbetter R.,TEMM Intl. Pty Ltd. | Liebenberg L.,North West University South Africa | And 4 more authors.
International Journal of Mechanical Engineering Education | Year: 2011

Flight simulators are regularly used in the undergraduate and postgraduate training of mechanical and aeronautical engineers. Due to advances in computing technology, several flight simulation-related tasks can now be accomplished in real-time using low-cost PC platforms and inexpensive commercial software. The difficulty in realising an educational flight simulator system with motion platform therefore lies with the design and construction of an effective motion platform. Costs become exorbitant when simulation platforms of more than two degrees of freedom (i.e. pitch and roll) are attempted. This paper describes the development of a drive system for a motion platform with two degrees of freedom (pitch and roll) for use in undergraduate engineering training. Use was made of offthe-shelf PC equipment and flight simulation software and hardware, together with commercial actuators and drive systems. The motion platform was manufactured from square tubing and consisted of three frames: the stationary main frame and, rotating inside this, the roll frame and pitch frame. These rotated relative to each other and were actuated by two similar-sized DC motors and gearbox/chain transmissions. The system effectively simulated the pitch and roll motions of commercial airliners, using a low-cost, easily maintainable motion platform. The educational value of the simulator was twofold: first, it was to be displayed in the science exploratorium (SciEnza) of the University of Pretoria; and second, it provided a platform on which mechanical (as well as electrical, electronic and computer) engineering students could conduct practical work in courses such as dynamics and control, and on which final-year and postgraduate students could conduct research. © Manchester University Press.


Du Plessis G.E.,North West University South Africa | Du Plessis G.E.,TEMM Intl. Pty Ltd. | Du Plessis G.E.,HVAC Pty Ltd. | Liebenberg L.,North West University South Africa | And 5 more authors.
Applied Energy | Year: 2013

An industrial energy efficiency improvement through the introduction of modern technology is an important demand-side management initiative. Cooling systems on South African mines have been identified as large electricity consumers. There is significant potential for energy efficiency improvement by the widespread introduction of variable speed drive (VSD) technology. An energy audit was conducted on 20 large mine cooling systems and potential savings and feasibility indicators were calculated. A pilot implementation study was also done on one mine to experimentally validate the estimated savings. In this paper, the results of the audit, the potential savings and the pilot study results are presented. It is shown that large-scale implementation of VSDs on mine cooling system pumps and fans is economically viable. A total annual electrical energy saving of 144,721MWh, or 32.2%, can be achieved. An annual cost saving of US$6,938,148 and CO2 emissions reduction of 132Mton is possible. The implementation of VSDs on mine chiller compressors will also result in large energy savings, but is not economically feasible at present. Results of the pilot study indicate an electricity savings of 29.9%. The results are important to decision makers and indicate the significant impact that widespread VSD usage on mine cooling systems can have on South African mine sustainability. © 2013 Elsevier Ltd.


Lidbetter R.T.,University of Pretoria | Lidbetter R.T.,TEMM Intl. Pty Ltd. | Liebenberg L.,University of Pretoria | Liebenberg L.,TEMM Intl. Pty Ltd.
2011 Proceedings of the 8th Conference on the Industrial and Commercial Use of Energy, ICUE 2011 | Year: 2011

Investigations into demand side reductions have been encouraged by the utility in sectors with high electricity consumption, such as the cement industry. It is responsible for 5% of the electrical consumption for the mining and industrial division of the country. It has also been estimated that by 2020 this sector will be ranked fifth for energy savings potential. This paper investigates the potential of a load-shifting scheme to reduce evening peak loads and save electrical costs on a raw mill at a South African cement plant. A simulation was performed, which showed that six hours of load-shifting could be achieved, without adversely affecting production. This was corroborated by a pilot study where the load was successfully shifted for six hours over a week-long period. The specific raw mill would achieve a reduction in yearly electrical costs of 2% when employing this load-shifting strategy. The results however showed that cost-saving opportunities are highly dependent on the reliability of the mills and on the change in production demand. Therefore, load-shifting schemes have to be highly adaptable on a daily basis to shift load when possible. © 2011 Cape Peninsula Univ of Tec.


Muller M.,ETH Zurich | Liebenberg L.,University of Pretoria | Liebenberg L.,TEMM Intl. Pty Ltd | Mathews E.H.,University of Pretoria | Young P.W.,The Aerospace Corporation
International Journal of Mechanical Engineering Education | Year: 2012

Unmanned aerial vehicles (UAVs) are commonly employed in undergraduate engineering curricula. Limited literature is, however, available for the lay design engineer or engineering student regarding the modelling, simulation and analysis of the fl ight dynamics of small UAV systems, especially pertaining to fl ight dynamics modelling. There is great demand for unskilled UAV designers to predict the stability of new designs, quickly, cheaply, and with relative ease, preferably during the conceptual design stage. This paper summarizes some salient techniques for performing quick characterization of the longitudinal dynamics of a small, electrically propelled UAV, by using freely available software such as Datcom+, AVL, XFLR5 and MotoCalc. The simulation outputs compare favourably with experimental results from a wind tunnel. The software was also used to provide accurate estimates of coeffi cients required for performing an analysis of the UAV's longitudinal dynamics. The proffered analytical techniques should greatly benefi t lay design engineers and engineering students venturing into the realm of UAV research. © Manchester University Press.

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