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    Moment-method analysis of waveguide diaphragms of arbitrary shape

    Konditi, D.B. ; Sinha, Sachendra N.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.2002.1159961
    Publication Year: 2002 , Page(s): 517 - 524 vol.2

    IEEE Conference Publications

    This paper presents a moment-method analysis of waveguide diaphragms/irises of arbitrary shape. The "generalised network formulation" for aperture problems has been used for formulating the problem in terms of an operator equation. Triangular patch modelling, using suitably defined basis functions, has been used to solve the operator equation. Various pertinent parameters have been evaluated and numerical results validated. The validated results are found to be in good agreement with the published data. Thereafter, data generated for new problems have also been given. View full abstract»

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    Implementing a pre-paid electricity system in a third world environment

    Bos, H.A. ; Brull, L.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    Digital Object Identifier: 10.1109/AFRCON.1992.624509
    Publication Year: 1992 , Page(s): 409 - 412

    IEEE Conference Publications

    The authors argue that the terminology presently used in the electricity dispensing market show a misunderstanding of the true market and a classical display of marketing myopia. Terms such as electricity dispenser and prepayment electricity metering imply that the system should be restricted to the collection of electricity charges only and that this is the first time that the supply authority can extract payment up front from the consumer. The authors seek to destroy the myopia presently in the market place and while doing so examine the difference between the implementation of an electricity dispensing system in a rural vs. an urban area, and look at the effect of a retrofit. Emphasis is placed on the market impact of the system View full abstract»

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    A spectral subtraction method for noise reduction in speech signals

    Mwema, W.N. ; Mwangi, Elijah
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1996.563142
    Publication Year: 1996 , Page(s): 382 - 385 vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

    A noise suppression algorithm for enhancing speech signals corrupted by additive white Gaussian noise is presented in this paper. The algorithm is based on the subtraction of estimated noise spectrum from the noisy speech spectrum. The performance of the algorithm is assessed by comparing the original clean speech and processed speech. An objective measure based on the log area ratios of a speech segment is used View full abstract»

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    Load profiling in an opening electricity market

    Marijanic, T. ; Karavidovic, D.
    AFRICON 2007

    Digital Object Identifier: 10.1109/AFRCON.2007.4401464
    Publication Year: 2007 , Page(s): 1 - 5

    IEEE Conference Publications

    With the opening of Croatian electricity market the system operators are confronted with new obligations. One of them is the necessity to know customers' load profiles, which are to be used for consumption planning and calculation of balance settlements. A method has to be implemented that would give a sufficiently accurate picture of hourly consumption of customers without appropriate meters. The paper presents currently used load profiles and the project that will establish Croatian standard load profiles. View full abstract»

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    Controlled switching of shunt capacitors

    de Grijp, M.H.B. ; Hopkins, R.A.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1996.563008
    Publication Year: 1996 , Page(s): 874 - 879 vol.2
    Cited by:  Papers (4)

    IEEE Conference Publications

    During field measurements on shunt capacitor banks several characteristics were investigated. For these measurements Eskom utilised its mobile transient measuring facility which is equipped with a 12 bit, Nicolet 500 system, a fibre optic system for measurement signal transmission and resistive/capacitive voltage dividers. For inrush current limitation during shunt capacitor bank energising a series damping network or a pre-insertion impedance is common practice. Reduction of transient phenomena is determined by a suitable choice of damping network element parameters or pre-insertion impedance. By precisely controlling the instant of closing it is possible to almost entirely to eliminate or reduce to a minimum, the impact of the inrush current phenomena. The inrush currents are of a moderate nature, but the substation busbar voltage can exhibit significant transients. In the case of back-to-back capacitor bank energising the impact on the circuit breaker itself is of major interest. Inrush currents of significant nature can flow. In most instances this can lead to unexpected and abnormal wear of circuit breaker contact systems. It is recommended for each new shunt capacitor bank application to consider the combination of a series damping network and controlled closing. Such a combined scheme offers an effective solution to different switching situations occurring in practice. A consideration of what represents a critical or noncritical switching application for either the network or the circuit breaker itself then becomes the basis whether or not to apply controlled switching View full abstract»

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    A projection-based joint probabilistic data association algorithm [multi-target tracking applications]

    van Wyk, B.J. ; van Wyk, M.A. ; Noel, G.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406682
    Publication Year: 2004 , Page(s): 313 - 317 Vol.1

    IEEE Conference Publications

    A novel projection-based joint probabilistic data association (PJPDA) algorithm is presented. The JPDA problem is formulated as a constrained optimization problem and solved using projection onto convex sets (POCS) methods. The PJPDA algorithm is extremely simple to implement, has no strenuous memory requirements and completely avoids the generation of feasible event matrices. Algorithm complexity is discussed and simulation results presented View full abstract»

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    Low-complexity constrained LMMSE estimator for the sparse OFDM channels

    Golovins, E. ; Ventura, N.
    AFRICON 2007

    Digital Object Identifier: 10.1109/AFRCON.2007.4401614
    Publication Year: 2007 , Page(s): 1 - 7

    IEEE Conference Publications

    In this article the constrained linear minimum mean squared error (CLMMSE) algorithm is presented for the multipath channel response estimation in the OFDM systems using equispaced and equipowered pilot subcarriers. It relies on tracking of the channel correlation and signal-to-noise ratio and has a low computational complexity due to the transform-domain processing and no matrix inversions required. The proposed algorithm exhibits a substantial performance improvement for the sparse channels (9 dB in MSE and 1.4 dB in BER), whereas for channels with the dense impulse responses its accuracy is equivalent to the LMMSE scheme with the robust design parameters. View full abstract»

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    Hybridisation of MoM and GMT for the numerical analysis of electromagnetic sources radiating in the vicinity of persons with implanted cardiac pacemakers

    Jakobus, U. ; Ruoss, H.-O. ; Geisbusch, L. ; Landstorfer, F.M.
    Africon, 1999 IEEE

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1999.821916
    Publication Year: 1999 , Page(s): 1041 - 1044 vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    An iterative combination of the MoM (method of moments) and the GMT (generalised multipole technique) is presented for the analysis of electromagnetic sources radiating close to a human body with implanted cardiac pacemaker. The metallic parts (source and pacemaker) are treated by MoM, while the influence of the smooth dielectric body is taken into account by GMT View full abstract»

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    Calculations of SAR around implanted cardiac pacemaker induced by wireless radio terminal

    Saito, K. ; Watanabe, S. ; Endo, Y. ; Takahashi, M. ; Ito, K.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072182
    Publication Year: 2011 , Page(s): 1 - 4

    IEEE Conference Publications

    Recently, electromagnetic interference (EMI) of an implanted pacemaker induced by a mobile radio terminal has been investigated. However, there are few studies of specific absorption rate (SAR) around the pacemaker induced by the mobile radio terminal. In this paper, the relation between position of pacemaker model embedded into the torso model, wireless radio terminal model and SAR has been investigated. As a result of calculations, possibilities of increasing the SAR were observed in some cases. View full abstract»

  • Freely Available from IEEE

    2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590)


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406604
    Publication Year: 2004

    IEEE Conference Publications

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    Experiments for undergraduate courses in electromagnetic theory and EMC

    Cloete, J.H. ; Reader, H.C. ; van der Merwe, J. ; du Plessis, F.E. ; Becker, L.H.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1996.563138
    Publication Year: 1996 , Page(s): 362 - 365 vol.1
    Cited by:  Papers (2)

    IEEE Conference Publications

    Discusses the third year course on electromagnetic theory in the Department of Electrical and Electronic Engineering at Stellenbosch, the follow up fourth year course on electromagnetic compatibility (EMC), and the experiments which have been developed in support of them View full abstract»

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    Networking Africa: a case for VoIP

    Chitamu, P.J. ; Vannucci, D.E.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.2002.1146863
    Publication Year: 2002 , Page(s): 361 - 366 vol.1

    IEEE Conference Publications

    Penetration of telecommunication services in Africa is generally quite low outside major cities. The reason for this is the use of technologies that do not scale well in terms of capacity versus coverage in low tele-density traffic areas. The advent of IP-based networking for voice and data services promises to provide cost-effective solution to the tele-density problem because it addresses the decentralisation of the access and switching levels of the network that are reportedly the most costly part of any national network. We propose a network topology to support Africa-wide VoIP networking by the interconnection of segmented area-wide networks. It is shown that using an IP-based access network and provisioning based on teletraffic area-wide network demarcations, we can achieve a network solution to support different services and address the needs of the different market segments in low-density traffic areas. View full abstract»

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    Automatic frequency control of an induction furnace

    Khan, I. ; Tapson, J. ; De Vries, I.
    Africon, 1999 IEEE

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1999.821891
    Publication Year: 1999 , Page(s): 913 - 916 vol.2
    Cited by:  Papers (3)

    IEEE Conference Publications

    Automatic frequency control enables a variable induction heating load to be driven at its resonant frequency, ensuring maximum power transfer to the load throughout the heating cycle. Analysis and experimental results of the resonance locked-loop are presented to illustrate the performance of the system View full abstract»

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    A critique on previous work in vision aided navigation

    Murcott, C. ; Du Plessis, F. ; Meyer, J.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072126
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    This paper presents a critique on previous work in the field of vision aided navigation, particularly in the fusion of visual and inertial sensors for navigation. Several improvements and updates are proposed for the existent systems. GPS receivers have allowed for accurate navigation for many vehicles and robotic platforms. GPS based navigation can, however, prove to be impractical in applications where there is no GPS reception such as underground, indoors or in some urban areas. This pertains, in particular, to many robotic applications where position must be known in global coordinates or relative to a reference point. An inertial navigation system (INS) can be used to calculate one's relative navigation state via dead-reckoning calculations. The downfall of a low-cost INS is the errors associated with the system. While these errors are initially small, integration causes large drift errors over time. To combat this problem, cameras can be used to estimate the errors present in the INS readings. These results can then be used to correct the navigation state output from the INS. While the motion estimations from the cameras are not error-free, this method is made highly effective because of the complementary nature of the errors from the cameras and INS. Several improvements are proposed for this method; algorithmically, in updates to its hardware, and with the introduction of graphics processors to improve computational performance. The overall system performance, individual steps, algorithms, and results are compared to results from similar works to those of the proposed improvements. It is shown that the accuracy, responsiveness and overall performance of the system can potentially be greatly improved. View full abstract»

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    Loss models of photovoltaic water pumping systems

    Lujara, N.K. ; van Wyk, J.D. ; Materu, P.N.
    Africon, 1999 IEEE

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1999.821902
    Publication Year: 1999 , Page(s): 965 - 970 vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    The paper presents loss models of photovoltaic (PV) DC and AC motor drive water pumping systems (WPS). The DC and AC motors are fed by power electronic converters with or without maximum power tracking. The models are developed with the objective of maximizing the conversion efficiency from the solar irradiation to the potential energy of water by taking into account the variations in the pumping head at a given insolation. The efficiency of the array, the pump and the motor are found to be the most critical parameters for the performance of the systems. In addition, matching of the drive system and the load with the insolation characteristic of the solar array is found to be critical, since maximum system efficiency occurs at a specific head, which varies as the insolation changes View full abstract»

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    Linear contactless power transmission systems for harsh environments

    Barnard, J.M. ; Ferreira, J.A. ; Van Wyk, J.D.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1996.562976
    Publication Year: 1996 , Page(s): 711 - 714 vol.2

    IEEE Conference Publications

    A linear contactless power transmission system is proposed as an alternative power supply to mobile loads used in harsh environments. Such a system comprises a core with secondary winding sliding along an extended primary winding. The transformer primary winding is the most limiting component in the system and formulas to optimize the design for different applications are given. Experimental results for a 5 m, 15 kVA sliding transformer are presented View full abstract»

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    Control strategies for the secondary cooling zone in continuous casting

    Camisani-Calzolari, F.R. ; Craig, I.K. ; Pistorius, P.C.
    Africon, 1999 IEEE

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1999.820898
    Publication Year: 1999 , Page(s): 435 - 440 vol.1

    IEEE Conference Publications

    A brief overview is given of current research undertaken by the authors in the continuous casting process with specific emphasis on the secondary cooling zone. The dynamic and steady state heat transfer model, discretisation of the model, open-loop spray chamber redesign, systems identification procedure, feedforward controllers and feedforward-feedback controllers involved in system design are discussed View full abstract»

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    Continuous representation of unevenly sampled signals - An application to the analysis of heart rate variability

    Tkacz, E.J. ; Kostka, P.S. ; Budzianowski, Z. ; Oleksy, W.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072162
    Publication Year: 2011 , Page(s): 1 - 7

    IEEE Conference Publications

    Various methods for the continuous representation of unevenly sampled physiological signals, especially of heart rate and heart rate variability have been published over the past two decades. Due to the mathematical difficulties of analyzing unevenly spaced event series or unevenly sampled signals, all of the previously described techniques are impeded by some severe limitations which result from either representing the signal based on an assumed and often insufficient physiological model of signal generation, or from simplifications in the selected signal processing tools. Though the described methods have their merits and allow sufficient description of heart rate in some special applications, there has been no systematic investigation into a continuous representation of unevenly sampled physiological signals which is free from any limitations or simplifying assumptions and which would allow an objective comparison of the known methods and the determination of the respective errors in order to decide which technique is the best suited for a specific application. In this paper a continuous representation of the point event series describing the temporal sequence of heart beats is presented which does not impose any limiting assumptions on the data analysis. The results obtained were validated through simulations in both time and frequency domains, and compared with the established techniques to allow the determination of errors at the specific times where the heart beats occur, as well as within the intervals between these sample points. View full abstract»

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    Effect of variation in modelling of generator saturation on electromechanical modes

    Kaberere, K. ; Petroianu, A. ; Folly, K.
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308173
    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    Several industrial-grade power system simulation tools are commercially available in the market. They are expensive to acquire and time-consuming to learn. As a result, very few institutions (utilities, academic/research organizations) can afford to use more than one power system simulation tool. The simulation tools differ in their components modelling. Different simulation tools can give different results for the same system model. Understanding the reasons for the discrepancies in the results is not a trivial task. In this paper, we investigate the effect of variations in modelling generator saturation. We carried out an eigenvalue analysis of a single machine infinite bus (SMIB) system using PSS/E, PowerFactory, EUROSTAG, SSAT, and MatNetEig. The simulation results show that the effect of saturation on the local modes is erratic and there is a need for further research on saturation representation in power system stability simulation tools. View full abstract»

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    Feasibility study of electricity theft detection using mobile remote check meters

    Doorduin, W.A. ; Mouton, H.T. ; Herman, R. ; Beukes, H.J.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406697
    Publication Year: 2004 , Page(s): 373 - 376 Vol.1
    Cited by:  Papers (2)

    IEEE Conference Publications

    Check metering is an effective method for measuring the losses and electricity theft in a low voltage (LV) reticulation network. Populating a LV reticulation network with permanent check meters is expensive. Electricity theft or tampering is a dynamic process. Current developments in the telecommunications industry make it possible to implement a mobile remote check meter. A data collection infrastructure and data mining software, combined with check metering, can provide valuable information regarding the network. Before devices are placed in the field, a study is conducted to determine the optimum stationary time period for detecting electricity theft in the area, based on available consumption data in the area. This paper discusses simulations and models based on data from pre-paid meters in order to determine the feasibility and method of operation of a remote check meter View full abstract»

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    Excluding some weak keys in the mceliece cryptosystem

    Ryan, J.A.
    AFRICON 2007

    Digital Object Identifier: 10.1109/AFRCON.2007.4401626
    Publication Year: 2007 , Page(s): 1 - 5

    IEEE Conference Publications

    A Goppa code which has a non trivial automorphism group is a weak key for the McEliece cryptosystem. A quasicyclic code clearly has a non trivial automorphism group. Hence any quasicyclic code is a weak key. Some new classes of quasicyclic irreducible Goppa codes have recently been established and it is conjectured that, in the binary case, these new classes contain all binary quasicyclic ireducible Goppa codes. Using simple numerical conditions on the parameters of a Goppa code, we show that if we adopt the parameters as suggested by McEliece himself for choosing Goppa codes in the implementation of his cryptosystem, then some such codes are weak keys. We suggest other parameters which we claim would reduce the probability of choosing a weak key. View full abstract»

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    Erlang's Ideal Grading in DiffServ modelling

    Glabowski, M. ; Hanczewski, S. ; Stasiak, M.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072139
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    Traffic overflow is one of the most effective mechanisms of the management of traffic distribution in telecommunications systems. The paper considers a possibility of using traffic overflow in present-day IP networks. Additionally, a new simplified method for the calculation of the blocking probability in overflow systems is proposed in the paper. The method is based on the model of Erlang's Ideal Grading (EIG) with multi-rate (multi-service) traffic and different availabilities. The method does not require calculations of the parameters of overflow traffic and its accuracy is not lower than the accuracy of other methods for the calculation of overflow systems with multi-rate traffic available in the literature of the subject. The results of the analytical calculations have been compared with the results of the simulations, which has confirmed the high accuracy of the proposed model. View full abstract»

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    New cellular array for the hardware implementation of very high speed digital filter

    Dawoud, D.S.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1996.562985
    Publication Year: 1996 , Page(s): 753 - 758 vol.2

    IEEE Conference Publications

    A new pipeline sequential processor system is proposed. The system takes the form of a cellular array the basic element of which is a sequential synchronous full adder. The proposed system is used to build a very high speed digital filter. The execution time of any term Ai .Xi (i=0, 1, …, N) of the digital filter equation is the time of three clock cycles. The time is constant and completely independent on the word length. The basic element of the proposed array consists of two flip-flops. The analysis of the logic capabilities of the flip-flop showed that it is possible to implement any of the sixteen possible functions of two variables directly in the flip-flop. The next state of the flip-flop represents the result of the logic function. The two flip-flops of the basic element are used to realise the function of the single-bit full adder, one to form the sum S and the other to form the carry Ci, where: S=X⊕Y⊕Ci-1, and Ci=X.Y+(X¯+Y¯).Ci-1 The complete hardware of the basic element, the cellular array and that of the digital filter are given. The new cellular array results in great saving in the computation time compared with the conventional techniques. A comparison is given between this new hardware and the conventional ones based on the time-hardware product as a criterion. The comparison proved that the new hardware reduces the time-hardware product View full abstract»

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    Hardware and software implications of creating Bluetooth scatternet devices

    Johnson, D.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406661
    Publication Year: 2004 , Page(s): 211 - 215 Vol.1
    Cited by:  Patents (1)

    IEEE Conference Publications

    The paper seeks to explain the practical issues encountered when implementing point-to-multipoint capable Bluetooth systems. System partitioning of the Bluetooth stack between the hardware components is a crucial component of any Bluetooth design and depends heavily on the bandwidth requirements of the product. The MIPS estimates of the various Bluetooth stack layers and some typical applications are presented. Open source Bluetooth stacks running in open source embedded operating systems are highlighted as a solution to building low cost scatternet capable Bluetooth devices View full abstract»

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    Analytical model of the radio interface in the UMTS with packet scheduling mechanism

    Stasiak, M. ; Wiewiora, J.
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308143
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    The paper presents the application of a new analytical model of the full-availability group carrying a mixture of different multi-rate traffic classes with compression property for modeling the WCDMA radio interface with packet scheduling. The proposed model can be directly used for modeling of the WCDMA interface in the UMTS network servicing different traffic classes with and without compression. The described model can be applied for a validation of the efficiency of the WCDMA interface measured by the blocking probability and the average carried traffic for particular traffic classes. View full abstract»

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    Parameter estimation of countercurrent ion exchange process for desalination of water

    Dube, N.M. ; Tzoneva, R.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406719
    Publication Year: 2004 , Page(s): 479 - 483 Vol.1

    IEEE Conference Publications

    A method for model development and parameter estimation of an ion exchange process for desalination of water is described. The model is based on the countercurrent flow of liquid and solid into the process columns. A discrete time model is presented. The method is based on using the least squares approach. Matlab and Simulink software programs for calculating unknown model parameters are developed. The results are given and discussed View full abstract»

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    Airborne satellite antenna mount and tracking systems

    Heev, S.D.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406676
    Publication Year: 2004 , Page(s): 289 - 295 Vol.1

    IEEE Conference Publications

    Communication mobile satellite antennas (MSA) are relatively large and heavy, especially airborne high gain antenna (HGA) systems for Inmarsat-H and HSD aircraft Earth stations (AES). Over the past decade, steering airborne antenna systems, which comprise a mechanical assembly, a control electronic system, a microwave electronic package and an antenna assembly (arrays and steering elements), have reduced considerably in physical size and weight. These reductions, brought about by greater EIRP from satellite transponders coupled with GaAs-FET technology at the receiver front end leading to higher G/N RF amplifiers, have initially made the fitting of shipborne antennas on trucks and airplanes a reality. A little later, airborne and vehicle-borne MSA were developed on the basis of these shipborne antennas. The MSA systems are required to be always pointed towards the satellite, in spite of vehicle motion. Therefore, the mount system is one of the main requirements, from the technical and rational viewpoints, in designing MSA systems. Several types of mount system are used, including mechanical and electrical among others, especially those concerned with shipborne MSA systems. In the case of airborne and vehicle-borne MSA, electrical pointing systems are preferable View full abstract»

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    Computational design of a multiplex magnetron cavity

    Chow Ting Chan, T.V. ; Reader, H.C.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1996.563168
    Publication Year: 1996 , Page(s): 523 - 527 vol.1

    IEEE Conference Publications

    A recently acquired local commercial multiple-magnetron industrial microwave oven showed serious design flaws. This led us to a survey of design methods and found that rigorous design methodology is not readily available. This view appears to be true nationally and in design papers generally. This paper examines the cross-coupling between the oven ports both experimentally, and numerically using a commercial finite element software package MSC/MicroWaveLab. Cavity field and power distributions are then highlighted allowing a discussion of sensible oven design View full abstract»

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    Design and FPGA implementation of digit-serial FIR filters

    Dawoud, D.S. ; Masupe, S.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406659
    Publication Year: 2004 , Page(s): 203 - 209 Vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

    The design of a digit-serial N-tap FIR filter with programmable coefficients is presented. The design considers the general case of a W-bit sample word and an M-bit coefficient word. The processing of the data within the filter takes place with full precision. The output data is truncated to W bits. The design introduces a new digit-serial multiplier that guarantees minimum processing time and reduces the hardware requirements. Sign-amplitude representation for the coefficients and two's complement for the input samples simplifies the circuit configuration and allows the use of one common two's complement circuit for all the filter section. A 100-tap, 8-bit word length version filter is implemented using an Altera FPGA device. The filter can be used in real-time processing with sample rate range from 7.5 to 22 MHz View full abstract»

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    Critical success factors for renewable energy technologies

    Stainforth, D. ; Staunton, G.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1996.563068
    Publication Year: 1996 , Page(s): 7 - 12 vol.1

    IEEE Conference Publications

    This paper describes a project to identify the key factors which need to be in place to maximise the probability that a renewable energy project or programme will succeed. These factors have been called critical success factors View full abstract»

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    Insights into the polarization behaviour of a long high birefringence photonic crystal fibre under low energy, ultrashort pulse excitation

    Ben Salem, A. ; Cherif, R. ; Zghal, M. ; Burger, J.P.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072170
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    A highly nonlinear polarization-maintaining (PM) photonic crystal fibre (PCF) utilized for supercontinuum (SC) generation is studied. The effect of fibre microgeometry on fibre parameters is determined using electron microscopy and finite element analysis. The positions of the slow and fast axes of the PM-PCF were experimentally determined in situ at the input and the output by using near and far field imaging of modes. Furthermore the polarization resolved transmission characteristics were probed with ultrashort optical pulses from a modelocked Ti:Sapphire laser at sub-100 pJ input energies. The polarization response was fitted with a simple incoherent pulse fragment model, to reveal the fibre's twist and input axis orientation. Experimental measurement of SC generation in the 2-m long PM-PCF is also presented. The spectrum spans greater than 1.5 octaves despite the low input energies. The effects of polarization state in these experiments are discussed. View full abstract»

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    National quality systems: the Portuguese experience

    Silva Girao, P.M.B.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1996.563083
    Publication Year: 1996 , Page(s): 73 - 78 vol.1

    IEEE Conference Publications

    An overview of the organisation of systems dedicated to the assurance and promotion of quality, at national (national quality systems) and at the European Union level, is presented. The Portuguese implementation of such a system is reported and its repercussions on activities in the electrical domain are analysed View full abstract»

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    Realization of pipelined multiplier-free FIR digital filter

    Dawoud, D.S.
    Africon, 1999 IEEE

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1999.820843
    Publication Year: 1999 , Page(s): 335 - 338 vol.1

    IEEE Conference Publications

    The paper introduces a high-speed multiplication-free realization for FIR filter. The realization is based on the use of a linear periodically time-varying (PTV) system and the use of radix-r recoding schemes for obtaining the filter coefficients. The paper combined and reformulated the Modified Booth multiplication algorithm and the filter operation in bit-level. As a result, two schemes are proposed. The structures can be used to build programmable FIR filter View full abstract»

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    Investigating performance of neural networks in authentication using keystroke dynamics

    Pavaday, N. ; Soyjaudah, K.M.S.
    AFRICON 2007

    Digital Object Identifier: 10.1109/AFRCON.2007.4401575
    Publication Year: 2007 , Page(s): 1 - 8
    Cited by:  Papers (1)

    IEEE Conference Publications

    Biometrics technology has emerged as the desired solution for a range of secure applications where a person's identity must be determined. Biometrics is currently controlling network and physical access in numerous high risk areas, including airport customs and immigration desks, financial malls among others. This paper compares applications of neural networks to the field of hardened password mechanism in a typical workplace environment. View full abstract»

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    The influence of eurocentricity on engineering courses and an approach to their transformation

    Shepstone, N.M.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1996.563019
    Publication Year: 1996 , Page(s): 928 - 931 vol.2
    Cited by:  Patents (1)

    IEEE Conference Publications

    This paper lists some problems facing the engineering profession, particularly, its bad image, the difficulty students have in transferring between tertiary institutions, and the lack of interest the public have in engineering. It shows that many of these problems are the result of two fundamental causes: the structure of the engineering degree and the content of the degree. The paper suggests changes that could be made to both these aspects of the engineering degree, and shows how these changes could solve many of the problems listed at the beginning of the paper. It ends by suggesting some areas in which further investigation is necessary, particularly the bureaucracy required to administer the new degree structure View full abstract»

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    Statistical clustering in the design of logical topologies for wide-area optical networks

    Gazendam, A.D. ; Leuschner, F.W.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.2002.1146835
    Publication Year: 2002 , Page(s): 209 - 210 vol.1
    Cited by:  Patents (3)

    IEEE Conference Publications

    A novel approach based on statistical clustering, using the Ward linkage as similarity metric, is proposed for designing optical network logical topologies. The influence of the geographic distribution of network traffic, and the intra/inter cluster traffic ratios on the number and positions of wide-area network hub nodes are investigated. View full abstract»

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    The operational experience of the first 400 kV feeder in the Southern African power pool

    Coetzee, M.C. ; Muller, D. ; Hurford, G.J.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1996.563077
    Publication Year: 1996 , Page(s): 48 - 51 vol.1

    IEEE Conference Publications

    This paper summarises the operational experiences of the first 400 kV tie line in the Southern African power pool (SAPP). This tie line interconnects the Northern utilities of the SAPP with the Southern utilities. This paper deals with the commissioning problems experienced initially and the operational experience gained View full abstract»

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    Coding and online transmitting system for medical research

    Zagursky, V. ; Smirnovs, S.
    Africon, 1999 IEEE

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1999.820819
    Publication Year: 1999 , Page(s): 279 - 283 vol.1

    IEEE Conference Publications

    A distributed data acquisition system is proposed which provides parallel and simultaneous coding and on-line transmission of signals. The parallel 64-channel distributed measurement system may be used in multichannel bioelectric measurements. The use of a 14-bit digital transmission format with high speed provided data acquisition with a very low level of noise. This system has high accuracy of measurement and performance in sampling and transmission in comparison with known analogs View full abstract»

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    Multi-user class pseudo-dynamic traffic assignment model with signal control

    Camynta-Baezie, G. ; Cassir, C. ; Bell, M.
    Africon, 1999 IEEE

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1999.820691
    Publication Year: 1999 , Page(s): 37 - 42 vol.1

    IEEE Conference Publications

    A multi-user class pseudo-dynamic traffic assignment model is presented. It combines deterministic and stochastic user-equilibrium route choice models and defines two classes of drivers; the guided drivers and the unguided drivers. Three signal policies are introduced into the model and the effect of these policies on drivers are presented View full abstract»

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    Rogowski coils for short duration (<10 μS) pulsed current (>10 kA) measurements

    Turner, G.R. ; Hofsajer, I.W.
    Africon, 1999 IEEE

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1999.821863
    Publication Year: 1999 , Page(s): 759 - 764 vol.2
    Cited by:  Papers (3)  |  Patents (4)

    IEEE Conference Publications

    Rogowski coils present a useful and accurate means of current measurement, especially where high rise times limit the use of magnetic materials. In this paper, a Rogowski coil design is presented, for application in pulsed power experiments. The use of digital processing as an aid to data analysis is introduced and experimental results are given View full abstract»

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    Four-quadrant current-regulated DC servo drive using a fuzzy logic-based controller

    Jahmeerbacus, M.I. ; Soyjaudah, K.M.S. ; Bhurtun, C. ; Oolun, M.K.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.2002.1159999
    Publication Year: 2002 , Page(s): 705 - 709 vol.2

    IEEE Conference Publications

    DC servo drives normally employ an internal current loop as well as a speed control loop requiring the use of a speed transducer. This paper presents a fuzzy logic controlled DC servo drive without the need for mechanical speed sensors. Speed estimation is performed from measurements of the input current and voltage to the motor. The latter is driven by a current-regulated voltage source DC-DC converter capable of operating in all four quadrants of the torque-speed plane. The fuzzy controller uses the calculated rotor speed to produce the armature current command necessary for matching the reference speed profile. The proposed system is shown to track the dynamic input speed settings and to reject step load disturbances with largely reduced settling times and steady state errors. View full abstract»

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    Design and development of high-Q microwave filters-past, present and future

    Vahldieck, R.
    Africon, 1999 IEEE

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1999.821927
    Publication Year: 1999 , Page(s): 1099 - 1104 vol.2

    IEEE Conference Publications

    Dielectric resonator filters are in high demand today in very narrow-band and low-loss applications for mobile telephone systems. They are individually tuned to specifications and due to their frequency-sensitivity are hardly amenable to mass fabrication. Therefore they are expensive. Future filter requirements will be dictated by a shift in operating frequency of communications systems towards shorter wavelengths, mainly the millimeter-wave regime to avoid the frequency congestion at lower frequencies. While at lower frequencies the lack of bandwidth requires narrow-band applications and thus extremely high-Q filter structures, at millimeter-wavelengths channels are not only wideband but so far can also be spaced farther apart. System specifications can therefore be satisfied with filters having lower Q-factor. The key question in those applications is, however, whether or not the filter structure is mass produceable. In this paper a brief review of the last 20 years of filter development is presented. Present day design procedures are discussed and an outlook with regard to future filter developments is given View full abstract»

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    Adaptive filtering for voltage quality control in industrial system

    Iuliano, G. ; Lo Schiavo, A. ; Marino, P. ; Testa, A.
    Africon, 1999 IEEE

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1999.821880
    Publication Year: 1999 , Page(s): 853 - 858 vol.2

    IEEE Conference Publications

    The active compensation of voltage fluctuations in industrial subsystems is considered. A solution based on an adaptive control of a fullbridge rectifier is proposed to compensate voltage fluctuations at supplying busbars. The controller is realized on an adaptive filtering scheme, which allows a real-time identification of the voltage disturbance View full abstract»

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    Optimising maintenance functions by ensuring effective management of your computerised maintenance management system

    Wichers, J.H.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1996.562991
    Publication Year: 1996 , Page(s): 788 - 794 vol.2

    IEEE Conference Publications

    Maintenance activity optimisation is one area that can help tremendously to optimise the overall performance of any industrial plant. To optimise maintenance activities, one needs to know, for a start, what plant items are maintenance critical. Apart form many things, these maintenance critical items must be condition monitored, either on line, off line or by the monitoring of process information, to ensure the overall enhancement of the plant in terms of availability, reliability, or general maintenance conditions. To manage and optimise predictive maintenance activities based on condition monitoring information, one needs to be sure that the correct parameters are identified, managed and condition monitored. For this a structured activity analysis method, a plant condition information system, and a definite link between these activities, the information systems and a maintenance management system is required. This paper presents a method called Front End Maintenance Analysis which has widely been applied in industry and proved to be an effective method of identifying parameters for condition monitoring and clearly shows the link between these parameters and a maintenance management system in general View full abstract»

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    Assessing the written word: The engineering students' experience

    Israel, H.F. ; de Jager, H.J.
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308073
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    Vygotsky's (1987) premise is that students write to learn, and that this learning stretches across the curriculum. The lecturer in the field of engineering has therefore to evaluate teaching and learning through writing tasks as they are traditionally known, and ask why assessment focuses on students' weaknesses - why does assessment instead not meet the student at his point of strength, and lead him from there? It is at this point that the various factors contributing to the learning experience of the student merge into one multi-faceted concept - assessment. Assessment skills are part of the learning process, yet equipping engineering lecturers with such skills in theory and practice is minimal. Assumptions are that if one is qualified in a content area, one can teach that content and objectively assess one's students. This is not always true. Reviewing assessment of the written word is vital because language is the means to academic success. The responsibility lying with the engineering lecturer when assessing writing tasks is further compounded by the education context, the worldview of the educator and the experience of the learner. Common issues confronting engineering educators and students emerge. This paper addresses some such issues. View full abstract»

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    Simple pattern synthesis for microwave dielectric heating

    Meier, I. ; De Swardt, J.B.
    Africon, 1999 IEEE

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1999.821932
    Publication Year: 1999 , Page(s): 1121 - 1126 vol.2

    IEEE Conference Publications

    Synthesis of microwave field patterns by interference of frequency coherent, phase modulated signals is proposed as a novel technique for dielectric heating. Particular delay/phase differences result in a distinct set of base patterns. Weighted and averaged the desired heat patterns are then synthesized. Alongside, a unified, clearer large signal source model for injection locking is introduced View full abstract»

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    Performance investigation of a sparse data compression technique with AWGN channel effects

    Schoeman, J. ; Linde, L.P.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406673
    Publication Year: 2004 , Page(s): 275 - 278 Vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

    The paper introduces a performance measure for data sources that may be used to evaluate the potential for good compression using a sparse source coding technique, as well as BER bounds in AWGN. The authors present comparative results of sparse source coding and, in terms of the introduced performance measure, complexity and error propagation in AWGN conditions. Simulation results show that the performance measure can be used effectively to predict the potential of a source for compression. Comparative PDF and BER results are shown for various sparseness levels in coded and uncoded systems View full abstract»

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    Automatic classification of combined analog and digital modulation schemes using feedforward neural network

    Popoola, J.J. ; Van Olst, R.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072008
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper presents an artificial neural network based automatic modulation classifier system which can be used to classify combined analog and digital modulation schemes. Four best known analog modulation schemes and five corresponding digital modulation schemes were considered. An approach that involves three different steps in developing an automatic modulation classification is presented. The first step involves the extraction of the statistical feature keys used as the inputs to the classifier. The statistical feature keys are extracted from instantaneous amplitude, instantaneous frequency and phase of the simulated signals using MATLAB code. The second step involves the development of the automatic modulation classifier based on a backpropagation neural network algorithm. The third step of the methodology involves the performance evaluation of the developed automatic modulation classifier with a related study from the research literature. Results obtained show that the developed classifier is accurate and sensitive to classification of the nine modulation schemes considered with an average success rate above 99.0%. View full abstract»

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    Potential for new digital subscriber loop technologies in selected African situations

    Hanrahan, H.E.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    Digital Object Identifier: 10.1109/AFRCON.1992.624493
    Publication Year: 1992 , Page(s): 358 - 360

    IEEE Conference Publications

    The author reviews modern developments in telecommunications transmission and services offered over the digital subscriber loop. Issues in provision of telecommunications in African low-income urban situations are discussed. Two particular services, the High Density Subscriber Loop (HDSL) and the Asymmetric Digital Subscriber Loop (ADSL), are examined. Their appropriateness for the African urban situation is examined. The HDSL is seen as offering significant pair-gain opportunities and a new approach to planning subscriber cable installations in areas with little or no telephone service penetration. ADSL is argued to have significant potential for delivery of educational material to urban schools View full abstract»

  • Freely Available from IEEE

    Proceedings of AFRICON '92


    AFRICON '92 Proceedings., 3rd AFRICON Conference

    Digital Object Identifier: 10.1109/AFRCON.1992.624403
    Publication Year: 1992

    IEEE Conference Publications

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    FACTS control by sampled regulator design

    Wang, H.F. ; Li, F.
    Africon, 1999 IEEE

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1999.820917
    Publication Year: 1999 , Page(s): 469 - 474 vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

    Sample regulator design was initiated by Astrom in 1980 and has been subsequently developed into a well-established methodology. This paper presents two applications of the sampled regulator design method for flexible AC transmission systems (FACTS) control in power systems: (1) AC voltage control by static VAr compensator (SVC); and (2) DC voltage control in a unified power flow controller (UPFC), demonstrated by example power systems View full abstract»

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    Are we adequately preparing new engineers for the future? The case for a more formal look at the management of technology and innovation

    Pistorius, C.W.I. ; Both, A.P.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    Digital Object Identifier: 10.1109/AFRCON.1992.624407
    Publication Year: 1992 , Page(s): 14 - 16
    Cited by:  Papers (1)

    IEEE Conference Publications

    It is argued that universities in South Africa should, in addition to compensating for the global trend of accelerated change, analyze the demands that will be placed on engineers in the South Africa of the future and adjust their curricula accordingly. It is suggested that the management of technology and technological innovation in particular should be stressed. It is concluded that, in order to produce engineers who can contribute towards building and sustaining a competitive technology base, it is necessary to produce engineers who have a sense of social and environmental responsibility and a wealth-creating mindset View full abstract»

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    Micro-controller based Internet phone

    Kaplan, S. ; Davies, J.R.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406680
    Publication Year: 2004 , Page(s): 307 - 311 Vol.1

    IEEE Conference Publications

    This paper describes the development of a low cost micro-controller based, stand-alone Internet telephone to be used as an alternative to conventional line telephones. Bandwidth usage has been minimized to allow for use with dial up connections. The hardware comprises of a controller board for an AWC86 SlimLinkreg web server-controller (AWC86), which comes with a real-time operating system (RTOS) and TCP/IP stack, and codec boards for G.729 annex A (G.729A) codec ICs-MAS3159Fs. Cost was the main factor in the selection of hardware. Signalling is performed by the session initiation protocol (SIP) using the session description protocol (SDP) to negotiate the attributes of the media session to be established. The G.729A frames are transported between the units using the real-time transport protocol (RTP). RTP is accompanied by the RTP control protocol (RTCP). Two phone units were developed that communicated directly with each other and not through intermediary servers View full abstract»

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    Automated surveillance and detection of foreign stationary objects

    Kiewiet, N.G. ; Roodt, Y. ; Roos, H. ; Clarke, W.A.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072153
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    CCTV systems are frequently monitored manually by a human observer. This human observer is typically responsible for dealing with tens or hundreds of cameras at a time. Potential security threats may easily be missed by the system's human operators due to fatigue or being overwhelmed by the amount of change in the images. The timely detection of security threats is an important attribute for any security system. A robust algorithm for detecting potential threats from a surveillance video is presented. View full abstract»

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    An investigation of switching and conduction losses in inverters under varying inductor ripple current

    Wolf, M. ; du T.Mouton, H. ; van der Merwe, J.W. ; Koeslag, F.
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308307
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper presents an accurate method of calculating the switching device losses in a half bridge DC-AC inverter. The analysis is based on an existing numerical method of calculating the inductor ripple current. The losses are calculated by replicating the exact current waveform flowing through the switching devices. This method allows for a more accurate loss calculation than the well-known existing analytical methods. The different methods are discussed and the results are compared. View full abstract»

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    Power upgrading by converting AC lines to DC

    Matele, M.L. ; Clerici, A. ; Valtorta, G.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    Digital Object Identifier: 10.1109/AFRCON.1992.624525
    Publication Year: 1992 , Page(s): 474 - 478
    Cited by:  Papers (2)

    IEEE Conference Publications

    The authors describe how power transfer capability can be maximized by using HVDC, and indicate that it is possible to increase the power 3.5 times by converting AC lines to DC. Both HV and EHV double circuit and single circuit AC lines of average characteristics have been used as an example for conversion to both monopolar and bipolar DC lines. Conversion to HVDC also reduces per unit losses and enhances reliability through improved lightning performance. HVDC operation also has well-proven advantages in optimizing the operation of the total system View full abstract»

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    Considerations on tariff strategies for nonsinusoidal conditions

    Bezuidenhout, S.L. ; Rens, A.P.J.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.2002.1160020
    Publication Year: 2002 , Page(s): 823 - 828 vol.2

    IEEE Conference Publications

    Voltage waveform distortion on the power grid increases commensurately with sophisticated solid-state energy conversion due to the rapid development in power electronics. Harmonic distortion directly affects revenue and operating costs of a utility and customers. Traditional energy rates do not reflect these costs. Tariff strategies to allocate the cost of waveform distortion are considered. It is proposed to be one solution to regulate the total harmonic pollution in a power system. View full abstract»

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    An optimization-based connection admission control method for IEEE 802.16 wireless networks

    Pachamanov, R.A. ; Pachamanova, D.A. ; Tsankov, B.P.
    AFRICON 2007

    Digital Object Identifier: 10.1109/AFRCON.2007.4401532
    Publication Year: 2007 , Page(s): 1 - 7
    Cited by:  Papers (2)

    IEEE Conference Publications

    The IEEE 802.16 standard specifies the air interface of broadband wireless access (BWA) systems supporting multimedia services. The applications are varied in their nature and demand different performance levels in order to maintain the appropriate quality of service (QoS). The network should guarantee the pre-defined QoS requirements through an adequate resource allocation and admission control schemes. In this paper we propose a connection admission control method that takes into consideration specific QoS parameters of the ongoing connections and the new requests. The method is based on an optimization approach where the maximum allowed mean delay and the mean data queue lengths corresponding to the connections are used as decision criteria for accepting the new requests for service. The solution of the defined optimization problem also gives the optimal resource allocation. Since solving the optimization problem for a large number of connections can be time consuming, we propose a simple and practical algorithm for obtaining the optimal solution. View full abstract»

  • Freely Available from IEEE

    Copyright


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    Digital Object Identifier: 10.1109/AFRICON.2004.1406762
    Publication Year: 2004 , Page(s): 0_4

    IEEE Conference Publications

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    Aspects surrounding Bluetooth ad-hoc scatternet formation

    Schulze, S. ; Leuschner, C.J. ; Erasmus, D.J.E. ; Hancke, G.P.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406656
    Publication Year: 2004 , Page(s): 185 - 189 Vol.1

    IEEE Conference Publications

    We describe the current research into Bluetooth scatternets at the University of Pretoria. Current research on Bluetooth scatternets focuses on three main areas: topology formation; packet routing; intra-piconet scheduling. Three scatternet topology formation algorithms are examined and compared. Scatternet scheduling algorithms are examined to determine which algorithm provides the best QoS for Bluetooth scatternets. A scatternet routing algorithm is selected based on certain usage requirements View full abstract»

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    Field experience with PRBS perturbation of a 133 MVA hydro-generator

    Strauss, J.M. ; Vermeulen, H.J. ; Coker, M.L.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.2002.1160017
    Publication Year: 2002 , Page(s): 803 - 806 vol.2

    IEEE Conference Publications

    Research has shown that the parameters of automatic voltage regulators (AVRs) and synchronous generators can be estimated from on-line measurements acquired while perturbing the automatic voltage regulator reference signal with a pseudo-random binary sequence (PRBS) signal. The technique has, however, been tested mainly for small round rotor machines under laboratory conditions. This paper presents field experience in applying PRBS perturbations to a 133 MVA hydro-generator to obtain data for verification of the technique for larger generators. View full abstract»

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    PID control of a nonlinear half-car active suspension system via force feedback

    Ekoru, J.E.D. ; Dahunsi, O.A. ; Pedro, J.O.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6071979
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    This paper presents the design of a two-loop, force/suspension travel PID control system, for a four degree-of-freedom (DOF), nonlinear, half-car active vehicle suspension system (AVSS). The two-loop system consists of an inner PID hydraulic actuator force control loop and an outer PID suspension travel control loop. Performance of the PID based AVSS is compared to a passive, nonlinear, half-car suspension system with the same model parameters. The simulation results showed the superior performance of the AVSS in the presence of the deterministic road disturbance. View full abstract»

  • Freely Available from IEEE

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    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    Digital Object Identifier: 10.1109/AFRICON.2004.1406794
    Publication Year: 2004 , Page(s): 798

    IEEE Conference Publications

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    Kitchen table testing of 10 GHz superconducting electronic circuits

    Fourie, C.J. ; Perold, W.J. ; Buttner, U.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406736
    Publication Year: 2004 , Page(s): 537 - 542 Vol.1

    IEEE Conference Publications

    As the clock speeds of experimental digital electronic circuits increase beyond the measurement ranges of commercial oscilloscopes, the testing and verification thereof becomes a significant problem. Superconducting circuits add further complications, such as 4 Kelvin operating temperatures, output signal levels of around 300 muV, and the need for comprehensive magnetic field screening. This article discusses the testing of such circuits with minimal equipment and very low budgets View full abstract»

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    Modeling of demand side shifting potentials for smart power grids

    Pollhammer, K. ; Kupzog, F. ; Gamauf, T. ; Kremen, M.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072110
    Publication Year: 2011 , Page(s): 1 - 5
    Cited by:  Papers (1)

    IEEE Conference Publications

    Outlining the potential of demand response or load shifting techniques is vital for the smart power grid. While different approaches exist on how to model the demand response ability of different consuming nodes or whole subsystems of the power grid, the existing approaches tend to show the maximum amount of shiftable energy at any given point of time without taking into account the correlation between the temporal duration of shifted energy and its amount. A different approach that tries to solve this question is presented. The outlined solution includes the possibility to include the estimation on possible rebound effects that could happen by introducing demand response techniques. View full abstract»

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    Reducing fuel consumption by using a new fuel-efficiency support tool

    van der Voort, M. ; Dougherty, M.
    Africon, 1999 IEEE

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1999.820687
    Publication Year: 1999 , Page(s): 27 - 32 vol.1
    Cited by:  Patents (1)

    IEEE Conference Publications

    A fuel-efficiency support tool has been designed, which includes a normative model describing optimal driver behaviour for minimising fuel consumption. If actual behaviour deviates from optimal behaviour, the system presents advice on how to change behaviour. Evaluation revealed that drivers used ~16% less fuel compared with `normal driving' View full abstract»

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    Using the oscillation test method to test for delay faults in embedded cores

    Vermaak, H.J. ; Kerkhoff, H.G.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    Digital Object Identifier: 10.1109/AFRICON.2004.1406859
    Publication Year: 2004 , Page(s): 1105 - 1110 Vol.2
    Cited by:  Patents (6)

    IEEE Conference Publications

    Continual advances In the manufacturing processes of integrated circuits provide designers the ability to create more complex and denser architectures and increased functionality on a single chip. The increased usage of embedded cores necessitates a core-based test strategy in which cores are also tested separately. The IEEE P1500 proposed standard for embedded core test (SECT) is a standard under development which aim is to improve the testing of core-based system chips. This paper deals with the enhancement of the test wrapper and wrapper cells to provide a structure to be able to test embedded cores for delay faults. This approach allows delay fault testing of cores by using the digital oscillation test method and the help of the enhanced elements while staying compliant to the PI500 standard. View full abstract»

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    A four-fingered robot hand with shape memory alloys

    Farias, V. ; Solis, L. ; Melendez, L. ; Garcia, C. ; Velazquez, R.
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308403
    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    This paper presents the design and implementation of a four-fingered human-size robotic hand intended for dexterous and grasping manipulation applications. The prototype hand has 3 degrees of freedom (DOF) per finger and 2 DOF in the thumb for a total of 11 DOF. Shape memory alloys (SMAs) micro-coils are embedded intrinsically within the hand structure to power the joints while exhibiting some advantageous features such as low-cost, lightweight, compactness and clean silent operation. To increase efficiency and decrease power dissipation, the SMA micro-actuators integrate magnetic bi-stable structures. Mechanical design, actuation approach and first prototype are presented and discussed. View full abstract»

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    Development of computer aided engineering package

    Kang'ethe, S.M. ; Hinga, P.K. ; Iwami, Y.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    Digital Object Identifier: 10.1109/AFRCON.1992.624542
    Publication Year: 1992 , Page(s): 545 - 547

    IEEE Conference Publications

    The authors discuss some of the issues involved in the design of a computer-aided control engineering package. These include the software life cycle as a necessary aspect of design of any software. The use of common data structures in the design of software and appropriate human-machine interface can make software more user-friendly View full abstract»

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    Improvement of the Ulco network voltage regulation using a phase shifting transformer

    Sithole, S. ; Mbuli, N. ; Pretorius, J.H.C.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072034
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    In networks feeding loads that vary from low levels during low loading and extremely high levels during high loading conditions, with lines providing supply to these loads being very long, voltage regulation within the acceptable range can be a challenge. In a case where such lines to the load centers constitute parallel corridors with different impedance characteristics, and therefore different loading properties, problems of regulating voltages within acceptable limits may be experienced. The previous paper [1, 2, 3, 4] proved that by changing the phase angle of the network connected in parallel, the voltage can be regulated. These voltages can be increased or decreased depending on the angle change. The Ulco network has the described characteristic and was used as a case study to observe network voltages during different loading conditions. This network experience overvoltages during lightly loaded conditions and undervoltages during heavily loaded conditions. The phase shifting transformer is one of the devices broadly used in power systems to change the power flows by changing the phase angle. This paper provides the analyses of peak and off-peak loading of the Ulco network voltages. The phase shifting transformer is then used to mitigate against voltage limit violation. View full abstract»

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    Design of a time-Frequency Domain analysis online laboratory utilizing the EMONA DATEx

    Asiimwe, A.T. ; Mwikirize, C. ; Musasizi, P.I. ; Tickodri-Togboa, S.S. ; Mwambela, A.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072116
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper presents the work undertaken to integrate the Frequency Domain Functionality of the EMONA DATEx into the iLabs Shared Architecture. The research was undertaken to improve the functionality of the online laboratory supporting time-domain analysis, which was developed at Makerere University in the 2008/2009 academic year. The laboratory is used as part of course work assessment for students offering the Communication Engineering course, under the Bachelors of Science in Electrical and Telecommunications Engineering Programmes. By introducing the frequency domain component in the laboratory, users are facilitated to investigate signal conversion between the time and frequency domains, and identify the associated frequency components. The laboratory also provides options for Power Spectrum and Power Spectral Density analyses. View full abstract»

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    Simple alignment technique for molding and transfer of 3D PDMS structure using the mechanical alignment jig

    Jinwoo Jeong ; Kukjin Chun ; Jongpal Kim ; Byeungleul Lee
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308216
    Publication Year: 2009 , Page(s): 1 - 4
    Cited by:  Papers (1)

    IEEE Conference Publications

    Simple alignment technique for the purpose of PDMS molding and transfer is proposed. In order to realize suggested technique, specially designed mechanical jig is devised. This jig helps the mechanical alignment and the clamping of the same-sized wafers. Silicon-on-glass wafer is used as a carrier substrate of the thin PDMS structure. 3D PDMS structure for the cap of sensor has been molded and transferred to the sensor using the jig. Though principle and procedure of alignment is very simple, relatively high alignment precision of 10 mum has been achieved. All caps of the sensor chips have survived without peeling during dicing process. View full abstract»

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    Maintaining and operating transmission infra-structure in a rural environment

    Debbo, G.A.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    Digital Object Identifier: 10.1109/AFRCON.1992.624473
    Publication Year: 1992 , Page(s): 279 - 282
    Cited by:  Papers (1)

    IEEE Conference Publications

    The author highlights the main problems associated with operating and maintaining transmission infrastructure in a mainly rural environment, as found in South Africa. Such problems are decreased reliability with subsequent decrease in availability and performance, a higher maintenance burden because of increased travel time in rural areas, difficulty in obtaining skilled technicians in rural areas, and an increased logistics support requirement. Three possible solutions for solving these problems are discussed, including the introduction of a protection network, the introduction of a network management facility, and using computer-based knowledge tools for skills development View full abstract»

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    Piezoelectric sensor array with evaluation electronic for counting grains in seed drills

    Meyer zu Hoberge, S. ; Hilleringmann, U. ; Jochheim, C. ; Liebich, M.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072063
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    A special application area of the sensor system presented here, is the detection of grain in seed drills. With the highly precise measurement of the seed, the crop yield can be strongly improved. Under the extreme environmental conditions inside of the seed drills, each single grain of very different seed species must be safely detected. Because of the touching piezoelectric measuring principle, the mounting contact mode of the sensor is either in the distributor head or in each of the seed hoses of the seed drill. Up to 15 thousand grains must be counted per second. For the detection of these high grain frequencies, a novel design of the sensor element was developed. A special evaluation electronic converts the analog sensor signals into binary pulses, which can be recognized as interrupts and counted by a microcontroller. View full abstract»

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    Exploitation of stream processing on graphical Processors in Inertial Navigation

    Roets, S.F. ; Meyer, J. ; Du Plessis, F.
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308388
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper focusses on implementing an inertial navigation system (INS) on a graphics processor unit (GPU). The GPU allows simultaneous processing of large amounts of data and multiple use of the algorithm at the same time. Using the stream processing abilities of the GPU an investigation is launched into the simultaneous running of several navigation algorithms (INS's) with different sensor error models for each INS algorithm. The simultaneous processing of several INS systems allows for faster simulation times and data analysis. Aiding an error perturbed INS with a Kalman filter (KF) is considered when tuning the KF to obtain the optimally tuned KF from n amounts of KF's. View full abstract»

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    Requirements of interworking wirelessLAN and PLMN wireless data network systems

    Chan, H.A.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406668
    Publication Year: 2004 , Page(s): 251 - 255 Vol.1

    IEEE Conference Publications

    The IEEE 802.11 family of wirelessLAN (WLAN) and the wireless data public land mobile network (such as 2.5G/3G/3.5G wireless) are broad band wireless data access network technologies that offer data network services to mobile users. They have different capabilities in distance range, data rate, and in other features, and may complement each other. Combining WLAN and PLMN wireless data through interworking will enable these LAN and WAN technologies to complement each other to enhance the available wireless network services. The advantages of interworking are of interest to users and service providers. The requirements of interworking are presented and discussed here. The technological implications of these requirements are also discussed. Interworking different wireless network systems requires internetworking the different networks, interoperability off the different systems, as well as the additional mobility across different networks, involving security, accounting, and other technologies. These requirements may be used to guide future developments as well as to point out technical issues that need future exploration View full abstract»

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    Automating control code generation

    Webster, M.R. ; Harley, R.G. ; Levy, D.C.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    Digital Object Identifier: 10.1109/AFRCON.1992.624427
    Publication Year: 1992 , Page(s): 99 - 102
    Cited by:  Patents (1)

    IEEE Conference Publications

    The development of an implementation tool for the automatic generation of high-performance control code is described. The environment considered will automate the generation of parallel real-time control code. The authors give an overview of the controller hardware platform and describe the software development system. The development system allows the user to program in a graphical block diagram format and specify the required real-time responses at this level. Software tools are provided to interpret the graphical input and automatically generate real-time control code suitable for execution on the target hardware. This project focuses on the transputer microprocessor and produces Occam 2 intermediate code View full abstract»

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    Enhancement of GMM speaker identification performance using complementary feature sets

    Lerato, L. ; Mashao, D.J.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406669
    Publication Year: 2004 , Page(s): 257 - 261 Vol.1

    IEEE Conference Publications

    This paper describes a way of enhancing speaker identification (SiD) performance using N-best list method which utilises complementary feature sets. The SiD process is first done by training the Gaussian mixture model (GMM) classifier using parameterised feature sets (PFS) to form speaker models. During testing, the likelihood of a talker, given a set of speaker models is measured. The performance of the SiD system is normally degraded as the population of speakers increases. This paper addresses this problem by using linear prediction cepstral coefficients (LPCC) to complement the errors obtained from the PFS and the final identification is performed on smaller population. Results obtained using 2-best list show performance improvement View full abstract»

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    Results on low-sensitivity non-recursive realizations for band-pass FIR digital filters

    Sanz-Gonzalez, Jose L. ; Medina-Gomez, F. ; Rodriquez-Diaz, F.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    Digital Object Identifier: 10.1109/AFRCON.1992.624454
    Publication Year: 1992 , Page(s): 201 - 204

    IEEE Conference Publications

    The authors compare frequency responses of direct and cascade realizations of FIR (finite impulse response) bandpass filters with fixed-point coefficients. The direct realization has better frequency response (under coefficient quantization) than the cascade realization if the transition bands are narrow. Usually, direct realization performs well in passbands and cascade performs well in stopbands View full abstract»

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    Reliability of an electrical mill motor

    Pretorius, C.J. ; Pretorius, J.H.C.
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308137
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper describes the use of vibration analysis as the means of a predictive and preventive maintenance tool. From the data gathered by means of vibration analysis a mathematical model was developed using reliability engineering tools such as the Weibull distribution. From this it can be seen that by trending data that is periodically recorded an accurate indication of equipment failure can be established. The result of this study is an indicative tool for maintenance personnel during and after predictive and preventive maintenance. View full abstract»

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    Automated generation of Poisson-Voronoi tessellations in R2 for NS (Nov 2003)

    Minnaar, M. ; Ngwenya, D.W.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    Digital Object Identifier: 10.1109/AFRICON.2004.1406857
    Publication Year: 2004 , Page(s): 1091 - 1097 Vol.2

    IEEE Conference Publications

    Stochastic point processes and geometrical objects can be used to represent communication network stations and architecture. This includes a combination of point processes, graphs and tessellations. This approach can be useful in simulation of large communication networks containing multilevel stations following an irregular point pattern. This research modeled the process using object-oriented approach. The implementation allows a Poisson point process at each level of the stations and the rules of a connected graph are realized by applying Delaunay triangles and Voronoi tessellations to the point process. A stochastic model was implemented in C++ and OTcl for NS2. Simulations were performed in MATLAB to verify the C++ code. View full abstract»

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    An adaptive thresholding method for automatic lung segmentation in CT images

    Lin-Yu Tseng ; Li-Chin Huang
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308100
    Publication Year: 2009 , Page(s): 1 - 5

    IEEE Conference Publications

    Cancer is one of the most serious health problems in the world. Lung Computer-Aided Diagnosis (CAD) is a potential method to accomplish a range of quantitative tasks such as early cancer and disease detection, analysis of disease progression, analysis of pulmonary function and perfusion, and automatic identification and tracking of implanted devices. For identifying the lung diseases, computed tomography (CT) scan of the thorax is widely applied in diagnose. The lung segmentation is the preprocessing step in most CAD systems. However, manually segmenting the lungs is tedious and taking lots of time for the large-sized CT databases. In this paper, we propose a novel lung segmentation technique that can determine the threshold for each CT slice in a patient stack and automatically do the lung segmentation. The accuracy is 98% when the method was tested on five patient stacks that contained 914 slices. View full abstract»

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    The use of a re-engineered motor and drive simulation tool for electrical engineering education

    Levin, A.G. ; Cruise, R.J. ; McCulloch, M.D. ; Landy, C.F. ; Clark, A.R.
    Africon, 1999 IEEE

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1999.821886
    Publication Year: 1999 , Page(s): 887 - 892 vol.2

    IEEE Conference Publications

    A drive simulation tool is re-engineered to allow nonspecialist users to model and analyse complex drive systems. This is achieved by re-designing the simulation environment to embody the problem domain. Towards this end a visual interactive modelling and simulation environment called Visual CASED (Computer Analysis and Simulation of Electrical Drives) has been developed. Visual CASED's ease of use has been demonstrated through its use as a teaching aid for a Generalised Machines course at the Department of Electrical Engineering, University of Witwatersrand View full abstract»

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    A new national standard for AC power and energy in South Africa

    Marais, E.L.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1996.563033
    Publication Year: 1996 , Page(s): 1002 - 1005 vol.2

    IEEE Conference Publications

    Some time ago, it was recognised that a need existed for higher accuracies in the measurement of AC power and for the establishment of a facility for the measurement of AC energy at the national standard level in South Africa. In 1995 it was decided to establish a new national standard for AC power. This standard is based on the current comparator principle and is intrinsic, which means that traceability for the AC power measurement can be achieved without the need for submitting an artefact for calibration to another laboratory at the national level. It was also decided to establish a facility for the measurement of AC energy. This paper details the history of the AC power standard in South Africa and the process that lead to the establishment of a new standard for AC power and energy. Details are given of the AC power and energy standard View full abstract»

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    Thin FC film for sidewall passivation in SCREAM process for MEMS

    Vrtacnik, D. ; Resnik, D. ; Aljancic, U. ; Mozek, M. ; Penic, S. ; Amon, S.
    AFRICON 2007

    Digital Object Identifier: 10.1109/AFRCON.2007.4401632
    Publication Year: 2007 , Page(s): 1 - 5

    IEEE Conference Publications

    SCREAM process for releasing micromechanical MEMS structures using plasma polymerized fluorocarbon thin film for trench sidewall passivation is reported. The developed process is designed as a one mask process, and all etchings and depositions are fabricated in the same etching system (standard capacitive coupled RIE), as one-step-one-run process. View full abstract»

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    Computer laboratory infrastructure in engineering education-a case study at Wits

    Nixon, K.J. ; Dwolatzky, B.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.2002.1146876
    Publication Year: 2002 , Page(s): 431 - 436 vol.1

    IEEE Conference Publications

    Computer laboratories used in engineering education are investigated by considering the requirements, constraints and infrastructures involved. Three primary requirements are identified: to provide access and connectivity, to support the teaching and learning process and to provide assessment facilities. The use of fat client and thin-client infrastructures in engineering education is discussed using two computer laboratories at Wits University (South Africa) as a case study. View full abstract»

  • Freely Available from IEEE

    2002 IEEE Africon. 6th Africon Conference in Africa (Cat. No.02CH37385)


    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.2002.1146795
    Publication Year: 2002

    IEEE Conference Publications

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    On-line remote and automatic switching of consumers’ connection for optimal performance of a distribution feeder

    Popoola, O. ; Jimoh, A. ; Nicolae, D.
    AFRICON 2007

    Digital Object Identifier: 10.1109/AFRCON.2007.4401536
    Publication Year: 2007 , Page(s): 1 - 6

    IEEE Conference Publications

    Load balancing on phases is performed using a conventional trial and error approach. With this approach, service interruption is unavoidable; hence rearrangement of consumers load distribution points on phases cannot be performed frequently. Also phase voltage and current imbalances might improve using this approach but the change does last for too long. To get the secondary distribution to operate at its optimal performance, a technique in the form of remote and automated technology is needed. This paper contributes such a technology at the low voltage side of the distribution network. The proposed static transfer switching technology is based on the open-transition switch that enables transfer or arrangement of consumer loads in a three-phase system within milliseconds and supervisory control system for effective co-ordination, computational and control of other intelligent units. View full abstract»

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    An investigation into the feasibility of using neural networks to control turbogenerators

    Shepstone, N.M. ; Harley, R.G. ; Jennings, G. ; Rodgerson, J.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    Digital Object Identifier: 10.1109/AFRCON.1996.563003
    Publication Year: 1996 , Page(s): 849 - 852 vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    This paper reports on the feasibility of using an online learning neural network as an adaptive turbogenerator controller to replace the automatic voltage regulator and the turbine governor. Results are presented which show that the neural network can control the turbogenerator at least as well as the conventional controller, but more importantly, its performance does not degrade when system conditions change View full abstract»

  • Freely Available from IEEE

    Proceedings of IEEE. AFRICON '96


    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1996.563066
    Publication Year: 1996

    IEEE Conference Publications

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    Development of an UAV for search & rescue applications

    Naidoo, Y. ; Stopforth, R. ; Bright, G.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072032
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (3)

    IEEE Conference Publications

    In the event of a disaster, there is an impending need for robotic assistance in order to conduct an effective search and rescue operation, due to their immediate permissible deployment. In this paper, the development of an unmanned aerial vehicle (UAV) intended for search and rescue applications is presented. The platform for the UAV is a quad-rotor type helicopter, simply referred to as a quadrotor. A plan for the mechatronic system integration was devised to combine the mechanical, electronic and software elements of the research. Once the system was modelled mathematically, a control strategy was implemented to achieve stability. This was investigated by creating a MATLAB® Simulink® numerical model, which was used to run simulations of the system. View full abstract»

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    Electric load management and information technology

    Palensky, P.
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308094
    Publication Year: 2009 , Page(s): 1 - 5

    IEEE Conference Publications

    Load management can be an important contribution to the electricity grid. Its main usage is improving grid stability (physical optimization) and optimize consumption patterns (financial optimization). In recent years, load management developed towards a more ldquoglobalrdquo scale. Wide area load management tries to translate the experiences of local load management to entire regions. It is Information Technology that enables this. This paper describes the various flavors of load management and names the open points before this idea can be deployed in a larger scale. View full abstract»

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    Multilevel harmonics current active compensator for DC feeding line

    Fioretto, M. ; Liccardo, F. ; Marino, P. ; Raimondo, G. ; Rubino, L. ; Torre, G.
    AFRICON, 2009. AFRICON '09.

    Digital Object Identifier: 10.1109/AFRCON.2009.5308121
    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    In this paper a new DC line current compensator is presented. The proposed converter is able to compensate very low amplitude current harmonics and is very useful in railway applications where harmonic pollution can produce interference in the signaling systems over DC lines. The active compensator is modular and composed by multiple cells connected in series and controlled in order to minimize the modulation current ripple. Moreover a design criteria are shown and simulation results demonstrate the effectiveness of the proposed solution. View full abstract»

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    Optimal pricing of telecomm services in a developing country: A game theoretical approach

    Sumbwanyambe, M. ; Nel, A.L. ; Clarke, W.A.
    AFRICON, 2011

    Digital Object Identifier: 10.1109/AFRCON.2011.6072082
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    Pricing is an important feature in preventing the misuse of any resource (specifically public resources) in a telecommunication network. The free-rider, tragedy of the anti-commons and tragedy of the commons problems can arise in the provision of public resources, when users of the resource have to contribute towards the cost of production. Selfish users in a group have the tendency to misrepresent preferences, so as to minimize their individual contributions and maximize their utilities, preventing the free rider and tragedy of the commons problems in telecommunications networks is crucial to prolonging the existence of a free or subsidized public resource. In this paper we develop a game theoretical approach to mitigating the free rider and tragedy of the commons problems in telecom networks. View full abstract»

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    Implementation considerations in a SIP based secure voice over IP network

    Aire, E.T. ; Maharaj, B.T. ; Linde, L.P.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    Digital Object Identifier: 10.1109/AFRICON.2004.1406653
    Publication Year: 2004 , Page(s): 167 - 172 Vol.1
    Cited by:  Papers (3)  |  Patents (4)

    IEEE Conference Publications

    The spread of IP-based LANs and the increasing use of voice transmission over these IP networks and the Internet have supported the growth and evolution of enterprise voice over IP (VoIP) systems. High quality IP telephony services over the Internet are becoming mainstream and are being implemented in a large number of service provider and enterprise networks. Many vendors are producing packages to take advantage of these telecommunication trends. These applications and services potentially introduce security leaks into a private network and also security issues across networks. These security issues arise due to the accessibility of the security interfaces, which is in turn due to the requirements of the VoIP protocols. Clearly, with the potential widespread implementation of packet networks, the security aspect of VoIP is becoming as important as quality of service (QoS) and next generation application issues. The paper takes an introductory look at the integration of standard security schemes with standard VoIP protocols as would be typically applied in a business type environment. Comparative analyses of the effects of firewall and VPN techniques on the quality of a single SIP-based voice call are carried out. The results of these assessments show that there is minimal negative impact on the quality of a single VoIP call when standard security schemes are implemented. It also provides some insight into issues to consider when implementing a secure, high quality VoIP network, especially for small-medium-micro sized enterprises (SMME) View full abstract»

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    Problems on high failure incidence of induction motors and protection

    Cele, L.Z. ; Chol, A.M. ; Chidzonga, R.F.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    Digital Object Identifier: 10.1109/AFRICON.2004.1406867
    Publication Year: 2004 , Page(s): 1143 - 1147 Vol.2

    IEEE Conference Publications

    This paper discusses results of investigations done at Combine Electric Motor Workshop - C.E.M. The need for the work arose from the unusually high failure incidence on one of the coal/ore haulage locomotives braking system, namely the 22 kW squirrel cage compressor induction motor for the hydraulic sub-system. Specific causes of the high failure incidences on the subsystem are explored and a PLC based motor protection scheme proposed. The protection scheme is three layered as opposed to the single layer i.e. current overload installed on the locomotive in question. The new scheme provides for voltage unbalance, thermal, current overload and leaks detection motor start/trip interlocks. Projected cost benefits and Implications on availability are significant when viewed in the context that it takes six coupled locomotives to haul the required economic tonnage using 200 wagons. View full abstract»

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    Implementation of integrated services digital network (ISDN) in developing countries: the case of Mauritius

    Seenundun, R. ; Bhurtun, C.
    Africon, 1999 IEEE

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1999.820852
    Publication Year: 1999 , Page(s): 351 - 356 vol.1

    IEEE Conference Publications

    In this paper ISDN implementation in developing countries is discussed based on Mauritius as a case study. The requirements in terms of basic telecommunications infrastructures for the setting up of an ISDN network are looked into. The problems which can be encountered in the process are analysed and possible solutions are identified View full abstract»

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    Synthesis of a decentralised fuzzy controller for level control of a four stage cascaded tank system

    Bart, Q.J.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.2002.1146818
    Publication Year: 2002 , Page(s): 119 - 122 vol.1

    IEEE Conference Publications

    A plethora of information exists to aid in the development of fuzzy controllers for both industrial and commercial applications. However, a very small subset of fuzzy set theory is really utilised for the synthesis of a fuzzy controller. In this paper it is shown how a decentralised fuzzy controller was designed to independently control the water levels in a four stage cascaded tank system. View full abstract»

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    Prevalence and success of portfolio management systems in south african new product development companies

    Van Gerve, A.D. ; Steyn, J.L.
    AFRICON 2007

    Digital Object Identifier: 10.1109/AFRCON.2007.4401503
    Publication Year: 2007 , Page(s): 1 - 7

    IEEE Conference Publications

    Product portfolio management in new product development (NPD) companies in developing economies was investigated to explore the applicability of best-practices and processes established for developed economy NPD companies. Case studies were conducted on South African NPD companies. The focus was on: 1. What is the prevalence of portfolio management processes in the NPD companies? 2. Is the process formalised and institutionalised? 3. How is the effectiveness of the process measured in terms of cost, schedule and quality? 4. How is the process linked to new product strategy? The results from four case studies showed that the companies followed different methods for managing their product portfolios. All did some contract development in addition to NPD. The larger companies followed processes that fit very well with the best practices and theories as implemented in developed economies. The smaller companies did not have many formalised processes for screening, evaluating and reviewing their product portfolios. They also established their product strategies informally and many of their portfolio decisions were taken ad hoc. These companies were not less profitable than the larger companies. The following conclusions could be made: 1. Portfolio management in developing economy NPD companies should recognize the need for contract development they experience in under scarce venture capital conditions. 2. While best practice portfolio management does not improve profitability, it is correlated with size and hence with past growth. 3. The dynamics of growth in portfolio management as contributor to company growth for developing economy NPD companies should be investigated. View full abstract»

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    Fast Fourier transform analysis of the auditory brainstem response: effects of stimulus intensity and subject age, gender and test ear

    Wilson, W.J. ; Aghdasi, F.
    Africon, 1999 IEEE

    Volume: 1
    Digital Object Identifier: 10.1109/AFRCON.1999.820821
    Publication Year: 1999 , Page(s): 285 - 290 vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

    The effects of subject age, gender and the test ear on auditory brainstem response (ABR) fast Fourier transform (FFT) results were examined at six stimulus intensities in 120 normal subjects. Subject age and gender, and stimulus intensity were shown to effect the ABR FFT results and must therefore be considered in any clinical ABR FFT analysis View full abstract»

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