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    Towards a converged network: Video streaming over WiMAX vs. HSDPA in the rural environment

    Odhiambo, M.O. ; Amimo-Rayolla, P.O. ; Kurien, A.M.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308196
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    As the telecommunications industry evolves towards a converged IP-Core network the role of cellular/wireless broadband technologies in achieving Long Term Evolution (LTE) must be greatly evaluated. This would in effect provide lessons for improvement and blueprints for final adoption in NGN (Next Generation Networks). The emergence of BWA (broadband wireless access) as a reliable player, in some cases a substitute for fibre/ADSL, maybe attributed to poor or non-existent copper/fibre, largely inefficient telecommunications management and/or ineffective telecommunications policies in mostly underserviced areas. In this paper, video streaming over existing 3G high-speed packet networks is evaluated against WiMAX as alternatives to fibre/ADSL. Simulation results show WiMAX was found to be a viable and better alternative barring capital expenditure (CAPEX) and operational expenditure (OPEX) considerations. HSDPA was found to achieve rates per user equipment (UE) that meet QoS needs for codec streaming Q-levels of 16 and 64 kbps. The 16 kbps codec rarely requires extensive preroll buffer requirements. However, WiMAX was found to perform better by at least three times for throughput and capacity. View full abstract»

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    Progress report on an engineering bridging programme

    du Plessis, G. ; Pauw, C.K. ; van Harmelen, T.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    DOI: 10.1109/AFRCON.1996.563073
    Publication Year: 1996 , Page(s): 28 - 31 vol.1

    IEEE Conference Publications

    The paper reports on the progress of the 1995 intake of freshman engineering students on the extended engineering programme at the University of Pretoria, South Africa. The programme is described briefly. Encouraging results are presented. A list of references with more detail is also provided View full abstract»

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    Effect of ADLash optical fibre cable on corona inception gradient and electric fields around the earth wire of the Apollo-Cahora Bassa HVDC transmission line

    Bussy, E.R. ; Ijumba, N.M. ; Britten, A.C.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406751
    Publication Year: 2004 , Page(s): 607 - 612 Vol.1

    IEEE Conference Publications

    A high voltage direct current power line consisting of a shield wire above a square bundle of conductors is modelled using the boundary element method. This is done to plot the electric field surrounding the shield wire outer strands and the surface electric field strength. It is demonstrated that the surface gradient of the bare shield wire is close to corona inception at the rated voltage. The model is then modified to include the representation of a fibre optic cable (ADLashreg) directly in contact with the shield wire. The electric field surrounding the shield wire and its surface electric field strength its again plotted. The relative permittivity of the ADLash is higher than the surrounding air and it is seen that the electric field at the air/dielectric/earth wire interfaces is enhanced. This is likely to increase the incidence of corona on the shield wire that could cause damage to the ADLash View full abstract»

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    Perimeter Echo Algorithm for network localization

    Chinnappen-Rimer, S. ; Hancke, G.P.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308395
    Publication Year: 2009 , Page(s): 1 - 5
    Cited by:  Papers (1)

    IEEE Conference Publications

    We propose an algorithm, the perimeter echo algorithm (PEA), to accurately determine the location of sensor nodes in a wireless network. The algorithm assumes a limited number of nodes (beacons) in the network are equipped with a location finding mechanism such as GPS. Nodes on the perimeter range of a beacon echo the beacons virtual ID to all nodes within range. This approach reduces the number of messages required to achieve network localization. The advantage of PEA is reduced power consumption and reduced flooding of the network because the beacon nodes only transmit an initialisation message once within a specific range and only those sensor nodes on the edge of a transmitting node's range, re-transmits the message. View full abstract»

  • Freely Available from IEEE

    2004 IEEE AFRICON - 7th AFRICON Conference in Africa - Title Page


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406606
    Publication Year: 2004 , Page(s): 0_3

    IEEE Conference Publications

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    A process framework for customising software quality models

    Sibisi, M. ; van Waveren, C.C.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401495
    Publication Year: 2007 , Page(s): 1 - 8
    Cited by:  Papers (1)

    IEEE Conference Publications

    The quality objective of many software organisations is to deliver software products that meet and or exceed customer expectations. The key to achieving this is to capture these expectations at the beginning of the project by clearly defining all quality requirements. The characteristics particularly defined in ISO/IEC 9126-1 (2001) provide the framework for specifying quality requirements. The ISO/IEC 9126-1 quality model is intended to be applicable to any type of software product or intermediate product. Before application this model needs to be tailored to a specific software and specific need. Since these characteristics cannot be directly measured this makes it difficult to directly prioritise and choose the most relevant characteristics and sub-characteristics. Hence a process framework that will link these characteristics and sub- characteristics to user needs is required. This will in turn help customise software quality models like ISO/IEC 9126-1 (2001) and other general software quality models. A process framework for customising software quality models is proposed in the text and it is further shown how this framework was applied in a real working environment in an attempt to quantitatively validate it. The results collected in the study showed that the framework could be used reliably in customising a generic software quality model at characteristic level only. The deviations at sub-characteristic level were due to unclear questions in the generated Generic Quality Questionnaire that resulted in misunderstandings. And the metrics used to create these questions were not fully tested for validity and reliability due to time constraints. Enhancements are discussed in the study and it is further shown how reliability can also be achieved at sub-characteristic level. View full abstract»

  • Freely Available from IEEE

    [Breaker page]


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406694
    Publication Year: 2004 , Page(s): 365

    IEEE Conference Publications

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    Current transformer measurements of distorted current waveforms with secondary load impedance

    Ackermann, D.W.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821864
    Publication Year: 1999 , Page(s): 765 - 768 vol.2
    Cited by:  Papers (2)

    IEEE Conference Publications

    This paper evaluates current measurements with current transformers under distorted current conditions. Power quality assessment relies on the accurate measurement of current and voltage. Current transformers exhibit a good frequency response under distorted conditions, although this is only valid for a low impedance load on the secondary of the current transformer. The effect of load impedance on the error of measurement for different scenarios are illustrated View full abstract»

  • Freely Available from IEEE

    Table of contents


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406763
    Publication Year: 2004 , Page(s): i - xxii

    IEEE Conference Publications

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    Recent developments in nonlinear device modelling techniques

    Van Niekerk, C. ; Schreurs, D. ; Meyer, P.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821928
    Publication Year: 1999 , Page(s): 1105 - 1110 vol.2

    IEEE Conference Publications

    An overview of recent developments in device modelling work performed at the University of Stellenbosch and the Catholic University of Leuven is presented. Results describing an accurate and robust multi-bias model extraction algorithm are presented. An introduction is also provided to the nonlinear network measurement system (NNMS) and results are presented to illustrate the implications for nonlinear modelling and design View full abstract»

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    The effect of thermal characteristics of power line insulators on pollution performance

    Vosloo, W.L. ; Holtzhausen, J.P.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 2
    DOI: 10.1109/AFRCON.2002.1159979
    Publication Year: 2002 , Page(s): 609 - 612 vol.2

    IEEE Conference Publications

    Power line insulators are heated by the sun and cool down during the night. The heating and cooling characteristics depend on the insulator material. The wetting of polluted insulators depends on various factors, such as humidity, ambient temperature and the temperature of the insulator surface. In this paper this phenomenon is investigated in the laboratory and on site for insulators made of various materials. 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
    DOI: 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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    Examining power line communication on Egypt’s low voltage grid for AMR network

    Helmy, A. ; Abdel-Rahman, M. ; Mansour, Mohamed M.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401462
    Publication Year: 2007 , Page(s): 1 - 7

    IEEE Conference Publications

    Electrical energy consumers are demanding better customer service, higher power quality, higher energy measurement accuracy and more timely data. Utility companies all over the world are being forced to find solutions giving greater information on the population's power consumption. The Automatic Meter Reading system (AMR) is one of the ways in which utilities are go-getting to achieve these goals. Power lines are one of the communication mediums used in the AMR system. However, power lines are a hostile communication environment. This paper describes a prototype for AMR system using power lines showing performance and reliability tests. The measurements are carried out on a sample of Egypt's low voltage network. View full abstract»

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    A software interface for an industrial control network using the CAN protocol

    Travis, A.R.L. ; Collier, M.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    DOI: 10.1109/AFRCON.1996.563049
    Publication Year: 1996 , Page(s): 1081 - 1082 vol.2

    IEEE Conference Publications

    The band period of a controller area network (CAN) interface written in software cannot be less than the time taken for a bit move, bit comparison and count with branch. Such an interface has been demonstrated, and baud rates of 0.5 MHz may be possible View full abstract»

  • Freely Available from IEEE

    [Blank page]


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406876
    Publication Year: 2004 , Page(s): 1186

    IEEE Conference Publications

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    Modular robotics in an African context

    Lund, H.H.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072081
    Publication Year: 2011 , Page(s): 1 - 7
    Cited by:  Papers (1)

    IEEE Conference Publications

    In this paper, we review the concept, development and use of modular robotic devices for education, health improvements, and business in Africa. The modular robotics inspired technology has the advantage of allowing any user easy access to a physical construction of new and advanced technology. We conceptualized several educational tools inspired by modular robotics for contextualized IT education in Tanzania, leading to a novel IT degree program and the development of East Africa's first science and business park in Iringa, Tanzania. The prototypes inspired by modular robotics were developed in the local, rural context and tested by local users in hospitals and rehabilitation centres. In this paper, we review the development of both modular building blocks for education and modular robotic tiles for rehabilitation in Tanzania. View full abstract»

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    Connection admission control (CAC) for QoS differentiation in PMP IEEE 802.16 networks

    Falowo, S.K. ; Ventura, N.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072112
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    Connection admission control (CAC) is an important element for quality of service (QoS) provisioning in wireless networks, such as IEEE 802.16 standard, which is also known as worldwide interoperability for microwave access (WiMAX). While the standard defines PHY and MAC requirements, CAC is left to the vendors to design and implement for service differentiation and QoS support. In this paper a Quadra-Threshold (QT) CAC scheme is proposed for IEEE 802.16 networks. The proposed CAC considers four different thresholds for the four connection types namely, UGS, ertPS, rtPS and nrtPS services. The QT scheme is used to prioritize each connection type for service differentiation and QoS support. A performance analysis model based on Markov chains is proposed and numerical results are presented to demonstrate the performance of the proposed scheme. The scheme when compared with complete partitioning scheme performs better in terms of blocking probability. 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.

    DOI: 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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    Hybrid BFSK/MPSK modulation employing GAC codes

    Soyjaudah, K.M.S. ; Jahmeerbacus, I. ; Bhurtun, C. ; Oolun, M.K.
    Africon, 1999 IEEE

    Volume: 1
    DOI: 10.1109/AFRCON.1999.820768
    Publication Year: 1999 , Page(s): 71 - 74 vol.1

    IEEE Conference Publications

    In this paper a hybrid binary frequency shift keying/multiple phase shift keying (BFSK/MPSK) modulation technique employing generalised array codes (GAC) and trellis decoding is proposed. The performances of the GAC employing the hybrid BFSK/MPSK are compared with those employing BPSK, MPSK schemes and the corresponding uncoded MPSK scheme View full abstract»

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    Design of magnetic-commutational wind energy generator for autonomous installations

    Mkrttchian, V.S. ; Shahinyan, /A/.G. ; Alexeevskij, V.V.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821900
    Publication Year: 1999 , Page(s): 955 - 958 vol.2

    IEEE Conference Publications

    For the small autonomous energy installations using the energy of the wind or small rivers it is not possible in regard of daily and seasons-related fluctuations, to provide constant volleying (rotation) speed and rotary installations power. In such cases using traditional generators of general purpose usually applied in industry is not quite justified and expedient. For the above-mentioned cases, a special purpose generator should be used, in which energy transformation is performed by using magnetic current commutation obtained during the rotation of the conductor magnetic anchor. The wind energy generator has revealed certain problems with discontinuities and disruption of automatic adjustment that can be eliminated using the sliding mode characterized by reduced order of mathematical support and feedback from discontinuities View full abstract»

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    Channel sharing policies for a mobile radio network providing wireless telephone and dispatch services

    Nofal, M.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    DOI: 10.1109/AFRCON.1996.563096
    Publication Year: 1996 , Page(s): 139 - 144 vol.1

    IEEE Conference Publications

    Channel sharing policies are proposed for a mobile radio network that provides telephone and dispatch services. The two services have different features and different service fields. The salient features and operational principles of both services are described. Based on these features, channel sharing policies are proposed. Analytical models are established for the proposed policies in order to gauge the performance of the network. Numerical results are provided and discussed for nominal network parameters View full abstract»

  • Freely Available from IEEE

    Author index


    Africon, 1999 IEEE

    Volume: 1
    DOI: 10.1109/AFRCON.1999.820984
    Publication Year: 1999 , Page(s): 0_23 - 0_24

    IEEE Conference Publications

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    The impact of a high differential group delay section on the output state of polarization of propagating light

    Musara, V. ; Ireeta, W.T. ; Wu, L. ; Leitch, A.W.R.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072013
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    Research to date has shown that high differential group delay (HiDGD) sections along an optical fiber network link are the major contributors to PMD. PMD has deleterious effects on propagating optical signals. In this paper, we show the effect a HiDGD section has on the output state of polarization (SOP) of propagating light. Experimental results in this paper show a reduction in the range of the output SOP spread with an increase in the DGD of the HiDGD section to a given asymptote (a minimum) i.e. when HiDGD ≥ 35ps. However, the output SOP spread and its asymptote solely depends on the location of the HiDGD section along the fiber link length. A small output SOP spread over the entire wavelength scan covers a few polarization states on the Poincaré sphere and vice versa for a large output SOP spread. The small output SOP spread over the entire wavelength range (50 nm in steps of 0.3 nm for this study) is an indicator that the polarization capabilities of optical telecommunication signals are restricted to minute SOPs. View full abstract»

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    Scraper winch motors on South African gold mines-an investigation into their failure

    Pritchard, J.F. ; Landy, C.F.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    DOI: 10.1109/AFRCON.1996.563152
    Publication Year: 1996 , Page(s): 435 - 440 vol.1

    IEEE Conference Publications

    This paper investigates some of the probable reasons for failure of squirrel cage induction machines driving scraper winches in South African gold mines. The paper shows the results of load current and voltage unbalance measurements that were recorded on winches in operation. There are further measurements showing the presence of time harmonics in the supply to some winches. More importantly, the paper shows the measured torque-speed curve of a typical scraper winch machine. This curve seems to indicate that there are significant space harmonics present in the air-gap of the winches, which may be causing rotor heating and premature bearing failure View full abstract»

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    Microprocessor control of hybrid energy systems

    van der Linde, H.A. ; Clark, I.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624458
    Publication Year: 1992 , Page(s): 217 - 220
    Cited by:  Papers (1)

    IEEE Conference Publications

    Remote area power supplies in the form of a hybrid system can be a very effective alternative in that the different components can be complementary. The authors describe a project whose aim was to develop a dedicated microprocessor control system to effectively manipulate a hybrid energy system so that available energy is efficiently utilized while at the same time the life span of battery banks is extended. The system was referred to as a Hybrid Energy System Manager (HESM). The HESM was connected to simulated and real energy sources and loads, and subjected to a series of tests. The results were very gratifying in that it performed as expected View full abstract»

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    Smart carpet for imaging of objects' footprint by photonic guided-path tomography

    Cantoral Ceballos, J. ; Nurgiyatna, N. ; Scully, P. ; Ozanyan, K.B.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6071986
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (3)

    IEEE Conference Publications

    We report on the concept, sensing principles, hardware and software implementation, as well as the performance of a demonstrator smart carpet, suitable for integration into the everyday environment. The deformation-induced transmission losses through strategically placed optical fiber sensing elements are measured and images of the footprints of objects in the imaged scene are reconstructed by an original method suitable for the limited datasets acquired. We discuss the potential for a very compact system, easy to integrate with the living environment and the outside world. View full abstract»

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    A T-resonator technique to measure admittance parameters of electrically short monopoles at radio frequencies

    Kwinana, P. ; Cloete, J.H.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406626
    Publication Year: 2004 , Page(s): 25 - 28 Vol.1

    IEEE Conference Publications

    An experimental technique to determine accurately the admittance parameters of electrically short monopoles is presented. Measurements were taken using an HP 8510C network analyser in the frequency range 45 MHz to 3 GHz. The experimental results compare well with numerical predictions. Both bare and insulated monopoles were studied View full abstract»

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    Torque performance of optimally designed three and five phase reluctance synchronous machines with two rotor structures

    Rakgati, E.T. ; Karnper, M.J.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406754
    Publication Year: 2004 , Page(s): 625 - 629 Vol.1

    IEEE Conference Publications

    In this paper, the torque performance of optimally designed 3- and 5-phase reluctance synchronous machines with different rotor structures are studied with sinusoidal currents. The rotor structures are the internal flux barrier rotor (IFBR) and the rotor with no internal flux barriers but only cut-outs (CRR). The torque performance of 5-phase machines is also investigated with sinusoidal-plus-third-harmonic current injection. The finite element (FE) calculation method is used directly by the optimisation algorithm (Powell method) to optimise in multi-dimensions the design of the reluctance machines under same copper losses and volume. From the FE results it reveals that under same copper losses and volume, optimised sinusoidal machines (3-phase & 5-phase) with the same rotor structure, result in almost the same torque. The results also show that the reluctance machines with the IFBR develop higher torque in comparison to the machines with the CRR. For the five phase machines with sinusoidal-plus-third-harmonic current, there is a slight increase in torque for the machine with the CRR and a decrease for the machine with the IFBR View full abstract»

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    Energy meter reading and tampering protection through powerline communication channel

    Naiman, S. ; Kissaka, M.M. ; Mvungi, N.H.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406799
    Publication Year: 2004 , Page(s): 821 - 826 Vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    Power utility companies have suffered revenue losses due to uncollected bills and energy tampering for many years. The use of remote monitoring system to overcome the problem using powerline communication has been identified as a solution. This needs tampering detection and transceiver capable of communicating data through powerline channel. We have identify different kinds of tampering and present simulated results of tampering detection and BPSK (DSSS) transceiver design for energy metering as a solution to the problem. The choice of spread spectrum BPSK modulation scheme is based on its robustness and its ability to spread signal into wide band to protect jamming and interference. The performance of the designed tampering detection, transceiver and selection of suitable parameter is verified using Matlab simulation. View full abstract»

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    The solid-state transformer concept: A new era in power distribution

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

    DOI: 10.1109/AFRCON.2009.5308264
    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (10)

    IEEE Conference Publications

    This paper considers the solid-state transformer concept as a viable alternative to the line frequency transformer in distribution circuits. The benefits of the concept are presented in terms of improvements to problem areas currently experienced on distribution networks as well as envisaged future or fringe benefits. Some barriers to universal acceptance of the concept are also identified, with the effects of these barriers analysed and discussed below. View full abstract»

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    Efficient spectral domain analysis of planar circuits using higher order expansion functions combined with fast system matrix computation methods

    Vaupel, T. ; Hansen, V.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    DOI: 10.1109/AFRCON.1996.562987
    Publication Year: 1996 , Page(s): 765 - 770 vol.2
    Cited by:  Papers (2)

    IEEE Conference Publications

    This article deals with several improvements of the spectral domain analysis of microstrip and coplanar circuits. Thus different kinds of expansion functions allow nonuniform meshing strategies with an improved current description. Furthermore a combination of acceleration methods with respect to the evaluation of the spectral domain integrals and special matrix fill techniques leads to a drastic reduction of the computational effort View full abstract»

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    A rapid technique for stator resistance extraction using key features of pseudorandom modified PWM fed induction motor impulse responses

    Benil, L. ; Burton, B. ; Hatley, R.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406869
    Publication Year: 2004 , Page(s): 1155 - 1159 Vol.2

    IEEE Conference Publications

    This paper explains how the electrical impulse response of a VSI fed induction motor can be extracted online from normal working data if the normal PWM signals are slightly modified to introduce a small pseudorandom binary sequence (PRBS), from time to time when measurements are required. It also explains how generic templates can be fitted to the measured impulse responses to obtain adaptive estimates of certain electrical motor parameters. A case study presents simulated and measured results of online rotor speed and stator resistance estimations based on the impulse response method. A novel technique of direct parameter extraction based on certain key points on the impulse response curve is developed to rapidly, yet accurately predict online rotor speed and stator resistance, (under various loads from standstill to full speed), which can be used for sensorless thermal condition monitoring and protection. The paper also discusses possible implementations for line operated machines equipped with standard soft-starter hardware. View full abstract»

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    What will customers demand of a new entrant telecommunications operator?

    Kennedy, I.G. ; Chitamu, P.J. ; Van Olst, R.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    DOI: 10.1109/AFRCON.2002.1146881
    Publication Year: 2002 , Page(s): 457 - 460 vol.1

    IEEE Conference Publications

    As part of its business plan, a new entrant operator (NEO) that is planning to enter an existing telecommunications marketplace will carefully analyse the demographics and demand patterns of its potential customers. The NEO will source the components of the network to meet this demand. This paper models the temporal and spatial characteristics of the likely demand. View full abstract»

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    Design of SSSC damping controller to improve power system oscillation stability

    Wang, H.F.
    Africon, 1999 IEEE

    Volume: 1
    DOI: 10.1109/AFRCON.1999.820931
    Publication Year: 1999 , Page(s): 495 - 500 vol.1
    Cited by:  Papers (21)

    IEEE Conference Publications

    This paper investigates the damping control function of a static synchronous series compensator (SSSC) installed in power systems. The linearized model of the SSSC integrated into power systems is established and methods to design the SSSC damping controller are proposed. In the paper, both cases of single-machine infinite-bus and multi-machine power systems are studied and example power systems are presented View full abstract»

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    Optimum step size determination for FDPM-based CIR estimator for OFDM systems

    Oyerinde, O.O. ; Mneney, S.H.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6071970
    Publication Year: 2011 , Page(s): 1 - 5

    IEEE Conference Publications

    Fast Data Projection Method (FDPM) subspace tracking algorithm has been demonstrated to exhibit high convergence rate towards orthonormality. This was shown to be the fastest among all competing algorithms of the same order of computational complexity. However, its convergence rate depends largely on the selection of its step size. Coincidentally, this is the only parameter needed to be specified for the algorithm, making its structure simple in comparison with other algorithms. In the original article, only the region in which the step size could be selected in order to ensure stability is given. However, in this article an optimum step size is determined through computer simulation for the FDPM algorithm in the context of channel impulse response (CIR) estimator for Orthogonal Frequency Division Multiplexing (OFDM) Systems. View full abstract»

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    Architecture and model of Profinet IO

    Poschraann, A. ; Neumann, P.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406884
    Publication Year: 2004 , Page(s): 1213 - 1218 Vol.2
    Cited by:  Papers (2)  |  Patents (2)

    IEEE Conference Publications

    This work presents the communication architecture and model for Profinet IO that has been currently released by the Profibus User Organization. Profinet IO provides the service definition and protocol specification for real time communication based on Ethernet, IP, and UDP for the field bus domain. It defines services and protocols mainly for communication between IO controllers (e.g. a PLC) and IO devices (e.g. Remote IO). It Includes a QoS architecture for real time control and alarm messages taking precedence over parameter, diagnosis, or Infrastructure messages Including other TCP or UDP based protocols. High message priorities In combination with a time division multiplexing approach with direct data link layer access provide short cycle times and low jitter. The IO device model itself is an enhancement of the Profibus DP device model. The enhancement includes a more flexible control access of one or more IO controllers in parallel to one IO device. Furthermore, address parameters and levels are enhanced too. The specification itself is according to IEC 61158 styles, which opens the possibility to be easily added in a new maintenance period of the standard. View full abstract»

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    Point-to-point rural telephone system

    Robertson, I. ; Evans, B.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624566
    Publication Year: 1992 , Page(s): 641 - 644
    Cited by:  Patents (1)

    IEEE Conference Publications

    A novel, low cost, UHF radio product has been introduced into the rural telephone market. It is one of a portfolio of products for rural telephone applications and is intended specifically for low density point-to-point use. The strategy during the design phase was not only to design a low-cost radio, but to allow savings in power costs as well. A further aim was to ensure that rural personnel, with basic training only, could easily maintain the new product in remote areas. Key issues in the development were: reduction in installed system cost, ease of maintenance, power management and lowering of current consumption, alarm and status reporting, high and low power transmitter options, fast installation, low initial capital outlay, and flexibility and adaptability View full abstract»

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    Promoting technology and technological careers. The role of non-formal education in South Africa

    Kramer, D.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624467
    Publication Year: 1992 , Page(s): 255 - 259

    IEEE Conference Publications

    It is noted that the promotion of careers in technology is difficult in South Africa. Good formal education in necessary for development. The crisis in formal education has resulted in the development of nonformal education which has been the vehicle for nongovernment involvement in education. Technology promotion has been via nonformal education. PROTEC, a privately funded nonformal program which is a good example of how technology and technological careers can be successfully promoted is discussed View full abstract»

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    Use of spatial interpolation technique for determination of geoclimatic factor and fade depth calculation in Southern Africa

    Odedina, P.K. ; Afullo, T.J.O.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401597
    Publication Year: 2007 , Page(s): 1 - 7
    Cited by:  Papers (1)

    IEEE Conference Publications

    Different authors have adopted various techniques to resolve the clear-air radio-propagation effect problems. These authors have presented different modeling techniques based on the radio propagation variables of the region in question. These variables are determinable from the local radio propagation data of the region in question. This paper uses the radiometeorological data collected in Durban, South Africa and in Maun, Botswana to determine the geoclimatic factor (K) variable. This is then used in implemented link designs to calculate the fade depth and worst month for these two locations. View full abstract»

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    A simulation study and analysis of certain properties of spectral null codes

    Ouahada, K. ; Ferreira, H.C.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072018
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    The technique of spectral shaping and the design of codes providing nulls at certain frequencies, as the case with spectral null codes, have enhanced digital signaling over communication channels like for digital mass recorders and metallic cables. The special structure of these codes help in investigating and analyzing certain of their properties. The possibility of links between these codes and other error correcting codes are also presented and discussed. Interesting results have shown a special structure of spectral null codes and their link to Low density parity check error correcting codes. View full abstract»

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    Figure-eight fibre lasers with NALM loops consisting of highly nonlinear dispersion shifted fibres for dense wavelength division multiplexing

    Schmieder, D. ; Swart, Pieter L. ; Booysen, A.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401621
    Publication Year: 2007 , Page(s): 1 - 7

    IEEE Conference Publications

    We describe 'Figure-of-Eight' fibre lasers with NALM (Nonlinear Amplifying Loop Mirror) loops of 100 m, 200 m 300 m highly nonlinear dispersion shifted fibre and 50 m photonic crystal fibre. Apart from the NALM loops the rest of the fibre lasers consisted of normal single-mode fibre (SMF28). The fibre lasers produced mode-locked and Q-switched pulses. By varying the length of the NALM loop we generated a variety of short and long stable high peak power and low peak power pulses in the range from 2 ns to 104 ns. The length of the pulses depends on the length of the NALM loop and the pump diode power. By changing the setting of the polarization controllers we can manipulate the amplitude of the pulses, produce high and low pulses, step pulses, double or multiple pulses. The period of the pulses is equal to the round trip time. We present pulse widths, pulse peak power and spectral measurements in dependence of the pump diode power, and discuss the shapes and spectra of the laser pulses with reference to the transmission curves. View full abstract»

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    Simulation and analysis of a component minimised three phase to single phase UPS topology

    Beber, D. ; Malengret, M.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821872
    Publication Year: 1999 , Page(s): 809 - 812 vol.2

    IEEE Conference Publications

    A new three-phase to single-phase uninterruptible power supply (UPS) topology is proposed. The new topology consists of a component minimised converter, whereby one three-phase IGBT module is used both as a phase controlled battery charger and an inverter. The proposed topology is also capable of input power factor improvement. This paper shows the simulation results View full abstract»

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    Why electronic and not electromechanical ELCBs ?

    Cohen, V.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    DOI: 10.1109/AFRCON.1996.562977
    Publication Year: 1996 , Page(s): 715 - 719 vol.2
    Cited by:  Papers (2)

    IEEE Conference Publications

    South Africa's 40 years of experience in the manufacture and application of sensitive earth leakage protection devices, together with the global experiences covering millions of installed units over several decades have resulted in a better understanding of not only the advantages, but also of the limitations of ELCBs. In Europe, where electromechanical ELCBs are used almost exclusively, the question of reliability of installed ELCBs has become a subject of major concern and attention. The popular hype regarding perceived reliability of electronic components was not sufficient to prevent the major South African manufacturer, some five years ago from changing their entire ELCB range from electromechanical to electronic technology ELCBs. The improvements in reliability that resulted from this decision are complemented by their freedom from safety performance limitations often found in lower specification electromechanical earth leakage circuit breakers View full abstract»

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    Development of a directional coupler to be used on the two-wire sections of dial-up telephone lines

    Nel, E.J. ; Braun, R.M.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    DOI: 10.1109/AFRCON.1996.562951
    Publication Year: 1996 , Page(s): 570 - 575 vol.2

    IEEE Conference Publications

    This project aims to develop a directional coupler for use on dial-up telephone lines. The need for such a coupler originated with the acceptance of the CCITT's (International Telegraph and Telephone Consultative Committee) V.32 bis recommendation regarding the operation of high-speed modems. This standard allows modems to communicate on the telephone network both simultaneously as well as within the same frequency band. The modems involved use a mechanism called echo cancellation to overcome this problem (with echo cancellation the modem subtracts that which it transmits from the signal on the line to get the signal it wishes to receive). However, a third party surveying the (two-wire sections of the) line is unable to interpret the signals on the line as there appears to be only one garbled signal. This paper develops the theoretical basis necessary for a directional coupler that will separate this garbled signal into its constituent signals and thus enable interpretation of such signals by a third party View full abstract»

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    Design methodology for a CMOS based power amplifier deploying a passive inductor

    Bozanic, M. ; Sinha, S.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401587
    Publication Year: 2007 , Page(s): 1 - 7
    Cited by:  Papers (2)

    IEEE Conference Publications

    This paper presents the design methodology of an integrated power amplifier (PA), and coins the methodology as a software routine: for a given set of PA specifications, CMOS process parameters, the routine computes the passive component values for a Class-E based PA. The routine includes the matching network for standard impedance loads. The program also provides its user with a spiral inductor calculator, which can be used to determine inductance and parasitic values for an integrated square planar spiral inductor. The same tool has the ability to extract SPICE (tSPICE) netlist of inductor geometry, which can be used in the post-layout simulations of the PA. Operation of the program was demonstrated by simulations in AMS 0.35 mum single-supply process for a 10 dBm, 2.4 GHz PA design. View full abstract»

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    Wireless sensor network gateway

    Steenkamp, L. ; Kaplan, S. ; Wilkinson, R.H.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308112
    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (2)

    IEEE Conference Publications

    Using wireless sensor networks is an effective way of gathering data and also opens up new sensing opportunities. Wireless sensor networks can be more useful if the data can be effectively retrieved from the sensor network. This paper describes the development of a gateway node for a wireless sensor network, implemented in TinyOS, using the AT91RM9200 ARM evaluation kit from Atmel. This node enables the user to remotely retrieve data from-, manage- and configure the network. View full abstract»

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    2D and 3D finite elements analysis to identify the influence of cylindrical voids in power cables

    Gutierrez, S. ; Sancho, I. ; Fontan, L.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308315
    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    This paper presents the numerical analysis of the influence of the presence of cylindrical voids in electric cables. Size, length and depth of voids are determinants of the discharge inception voltage. This analysis has been done with 2D and 3D finite element models and results have been compared with analytical formulas. The influence of depth in cylindrical voids has been analysed and discussed. View full abstract»

  • Freely Available from IEEE

    [Front matter]


    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308067
    Publication Year: 2009 , Page(s): c2

    IEEE Conference Publications

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Design and FPGA implementation of digit-serial FIR filters

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

    Volume: 1
    DOI: 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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    A practical evaluation of harmonic emission assessment

    Serfontein, D. ; Rens, J.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072151
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper reports an evaluation of harmonic emission assessment. The results obtained by the Harmonic Vector Method are correlated to the behavior of harmonic active power by means of synchronized measurements in a three-phase power system. View full abstract»

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    A radio frequency MOSFET driver

    Swart, A.J. ; Pienaar, H.C.V. ; Case, M.J.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406737
    Publication Year: 2004 , Page(s): 543 - 546 Vol.1

    IEEE Conference Publications

    High power MOSFETs have become synonymous with power electronics applications. The ability of high power MOSFETs to act as a switch makes it the ideal switching device, where maximum voltage and zero current must occur when the device is open. When closed, the MOSFET must allow maximum current to flow with zero voltage across it. This technique of switching between maximum and zero voltage across the high power MOSFET is readily achieved at frequencies below 1 MHz. Raising the frequency to within the radio frequency range has often proved a problem since high power MOSFETs tend to have a frequency cut-off point. This paper attempts to address the switching habits and limits of high power MOSFETs within the radio frequency range by means of computer simulation and experimental verification View full abstract»

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    Small, low cost and high performance filters for mobile telecommunication

    Chuma, J.M. ; Mirshekar, D. ; Masupe, S. ; Kepaletswe, T.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406842
    Publication Year: 2004 , Page(s): 1011 - 1014 Vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    In the market where price and performance are tough to match, size has now become extremely important factor for the mobile phones base stations. At the current mobile communications bands, air-filled filters are being used and tend to be bulky. The dielectric loaded comb line filter is proposed to reduced the size of the filters and enhance the performance of the filters. An eighth-order canonical combline filter is designed and the measured results show improved performance. View full abstract»

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    Fusing theory and practical in a curriculum for engineering students - A case study

    Swart, J. ; Sutherland, T.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401497
    Publication Year: 2007 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    Engineering students at the Vaal University of Technology are exposed to both theoretical and practical instruction within their specified disciplines. This provides the students with greater learning opportunities, which is a core academic function of a university of technology. The department of Electronic Engineering comprises one of eight departments within the Faculty of Engineering and Technology that emphasizes the importance of practical instruction for engineering students. This department focuses primarily on finding solutions to industrial problems in the power electronics and telecommunications world. This paper will attempt to highlight the importance of fusing theory and practical in a curriculum for engineering students. Two different approaches exist in this regard, namely presenting the theory before the practical and the practical before the theory. Both approaches were included in a module, Radio Engineering III, which serves as the case study for this paper. It comprises five different theory sections and 10 practical assignments. Most of the engineering students enrolled for this module successfully completed the practical work, which was designed with both approaches in mind. A post-practical survey revealed that the students felt that the practical work done in the laboratory was relevant to the theory work done in the classroom. It also revealed that students enjoyed the practical work, acquiring needed skills relevant to their engineering discipline. View full abstract»

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    Optimization of resources for H.323 endpoints and terminals over VoIP networks

    Nlend, S. ; Swart, Theo G. ; Clarke, W.A.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072160
    Publication Year: 2011 , Page(s): 1 - 5

    IEEE Conference Publications

    We suggest a method of optimizing resource allocation for real time protocol traffic in general, and VoIP in particular, within an H.323 environment. There are two options in the packet network to allocate resources: aggregate peak demand and statistical multiplexing. Statistical multiplexing, our choice for this case, allows the efficient use of the network resources but however exhibits greater packet delay variation and packet transfer delay. These delays are often the result of correlations or time dependency experienced by the system's queue due to the variations observed in different point processes that occur at a point of time. To address these issues, we suggest a queuing method based on the diffusion process approximated by Orstein-Ulenbeck and the non-validated results of Ren and Kobayashi. View full abstract»

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    The PV grid-connected demonstration system of University “Politehnica” of Bucharest

    Craciunescu, A. ; Popescu, M.O. ; Popescu, C.L. ; Ciumbulea, G.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308077
    Publication Year: 2009 , Page(s): 1 - 4

    IEEE Conference Publications

    In 2006, at University Politehnica of Bucharest, in the framework of the European demonstration project PV-enlargement, and of the Romanian project ldquoPV gridrdquo, a rooftop grid-connected photovoltaic power generation system of 30 kWp has been installed. This is a double array PV system containing two kinds of silicon modules: crystalline and amorphous. The installed power of crystalline modules is of 27.36 kWp and that of amorphous modules is of 3.24 kWp. This paper gives a survey of amorphous silicon array performances during 12 representative working months under specific operational and environmental conditions of Bucharest geographical location. View full abstract»

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    Adaptive time-varying beamforming for source localization and tracking in nonstationary environment

    Katkovnik, V.
    Africon, 1999 IEEE

    Volume: 1
    DOI: 10.1109/AFRCON.1999.820832
    Publication Year: 1999 , Page(s): 309 - 314 vol.1

    IEEE Conference Publications

    The proposed beamformer in two aspects is different from the conventional one. The weights are dependent on time and two parameters θ and θ'. Maximization of the beamformer power on θ and θ' gives estimates of direction-of arrival (DOA) and its first derivative. Simulation confirms an improved tracking ability of the new algorithm View full abstract»

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    Towards inexpensive robots for science & technology teaching and education in Africa

    Booysen, T. ; Rieger, M. ; Ferrein, A.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072042
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    As technology becomes a greater part of our everyday lives it becomes more difficult to keep young children interested and engaged using conventional educational methods. While it can be observed that youngsters have only a few problems with operating their cell phones, it does not mean that this prepares them well for the challenges of the 21st century. Additional education is required that teaches the basic principles of science and technology without scaring the youngsters away from the subject while still keeping them engaged in the learning process. Educational robotics has proven itself to be a good vehicle for educating pupils with thousands of learners participating in robotic competitions such as RoboCup Junior world-wide. In this paper we report on our first steps towards developing an inexpensive educational robot that is suited (a) for participating in competitions such as RoboCup Junior and (b) for university education and research. View full abstract»

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    The value of supplemental instruction in conceptual learning

    Hillman, J.C.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    DOI: 10.1109/AFRCON.1996.563124
    Publication Year: 1996 , Page(s): 288 - 292 vol.1

    IEEE Conference Publications

    Engineering undergraduates have difficulty with courses that are conceptual in nature. The internalisation of concepts and the development of problem solving skills is achieved by individuals in a variety of ways, relatively few of which are either known by lecturers or actively taught. A self-teaching initiative known as supplemental instruction (SI) can overcome these problems by encouraging students to learn from the experiences of others by participating in structured group discussions which are facilitated by senior students. This paper describes the development and results of an SI programme within a first year electrical engineering course and concludes that it is both an efficient and cost effective method of improving student learning, particularly for those from an educationally disadvantaged background View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Superconducting COSL building blocks for implementation in ultra-high speed logic circuits

    Rabie, F.J. ; Perold, W.J.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821950
    Publication Year: 1999 , Page(s): 1197 - 1202 vol.2

    IEEE Conference Publications

    Complementary output switching logic (COSL) is used to define building blocks for ultra-high speed (~20 GHz) logic circuits. The family consists of the standard logic functions OR, NOR, AND, NAND and XOR. The building blocks include a new single gate inverter and various latch functions. Changes in the layout of the COSL gates are proposed to improve the uniformity of current distribution in the gates, which will, in turn, prevent unwanted field concentrations View full abstract»

  • Freely Available from IEEE

    1999 IEEE AFRICON - 5th AFRICON CONFERENCE IN AFRICA


    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821826
    Publication Year: 1999 , Page(s): iii - xiv

    IEEE Conference Publications

  • Freely Available from IEEE

    [Breaker page]


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406704
    Publication Year: 2004 , Page(s): 409

    IEEE Conference Publications

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Image registration, parameter tuning and approximate function evaluation, using the genetic algorithm and digital image warping

    Pagliari, G.M. ; Greene, J.R.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    DOI: 10.1109/AFRCON.1996.562943
    Publication Year: 1996 , Page(s): 536 - 541 vol.2

    IEEE Conference Publications

    A common problem in image processing is image registration. The problem is finding the parameters of a noisy, multi-modal, multi-dimensional, image warping function which aligns two images. An image registration program, which used a genetic algorithm as the function optimiser, was designed. The settings of the program were automatically tuned with a second genetic algorithm. Monte Carlo analysis was used to improve the results View full abstract»

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    Application of finite state machines in hybrid simulation of dc-dc converters

    Ocaya, R.O. ; Wigdorowitz, B.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401529
    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (3)

    IEEE Conference Publications

    Much attention is currently being directed at nonlinear effects such as bifurcations, sub-harmonics and chaos in conventional and hybrid power electronic converters (PECs). Traditionally, PECs have been difficult to model and simulate because of the discontinuous nature of their underlying differential equations. This work suggests a modeling and simulation framework for a PECs that employs a Matlab/Simulink based finite state machine (FSM) in the context of hybrid systems theory. The literature contains mostly abstractions on hybrid simulation and few suggestions of practice. The approach is illustrated with the boost topology. The simulations are subsequently compared and contrasted with PSpice results. View full abstract»

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    An energy-efficient routing protocol for Hybrid-RFID Sensor Network

    Nokonoko, D.M.B. ; Lusilao-Zodi, G.A. ; Bagula, A.B. ; Dlodlo, M.E.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6071995
    Publication Year: 2011 , Page(s): 1 - 7

    IEEE Conference Publications

    This paper proposes an integration architecture that combines conventional wireless sensor nodes, sensor-tags, hybrid sensor nodes and a base station into a smart network named Hybrid RFID-Sensor Network (HRSN). The HRSN as built presents an energy imbalance problem among nodes. This is due to the hybrid nodes sensing energy consumption, which constitutes a large part of the network's residual energy. To implement the HRSN efficiently, a routing protocol that distributes the energy dissipation evenly among all nodes is proposed. The proposed routing protocol is a centralized cluster based protocol that assigns nodes different roles in the network based on their sensing energy properties. The algorithm achieves further energy reduction by letting the base station handle the key tasks, such as cluster formation and assignment of time. Simulation results demonstrate that the proposed routing protocol achieves higher energy efficiency than Low Energy Adaptive Clustering Hierarchy (LEACH) and LEACH-Centralized (LEACH-C). The algorithm also significantly prolongs the life span of the nodes with high-energy consumption. View full abstract»

  • Freely Available from IEEE

    [Blank page]


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406832
    Publication Year: 2004 , Page(s): 976

    IEEE Conference Publications

  • Full text access may be available. Click article title to sign in or learn about subscription options.

    Automated component-handling system for education and research in mechatronics

    Vermaak, H. ; Jordaan, G.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401627
    Publication Year: 2007 , Page(s): 1 - 7
    Cited by:  Papers (2)

    IEEE Conference Publications

    Mechatronic practitioners are engaged in the assembly and maintenance of complex machines, plants and systems in the engineering sector or in organisations which purchase and operate such mechatronic systems. Mechatronics, often described as the synergy of mechanical, computer systems and electronic technologies, is increasingly being singled out as a core focus by both the education and business sectors. This international trend is also evident in South Africa and Engineering Faculties now have to provide students with the opportunity not only to acquire theoretical knowledge in Mechatronics but also to develop skills in implementing and designing mechatronics systems. View full abstract»

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    DC motor control via high order differential feedback control

    Nyabundi, S.A. ; Qi, G. ; Hamam, Y. ; Munda, J.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308165
    Publication Year: 2009 , Page(s): 1 - 5
    Cited by:  Papers (1)

    IEEE Conference Publications

    In practice, there are many motor systems whose models are usually unknown or partially unknown. However, the majority of control schemes focus on model-dependent techniques. To cope up with unavailable dynamics, a model-free controlling problem for a DC motor system is investigated in this study. A robust higher-order differential feedback controller (HODFC), which does not depend on the model of the controlled DC motor system, is applied. The controller only utilizes the information of the measured output and the given objective as well as the extracted differentials of those via higher-order differentiator (HOD). Simulation results show that HODFC successfully controls the uncertain DC motor system, and can drive its trajectories to desired steady states subject to unknown bounded disturbance. Stability, convergence and robustness of PID, fuzzy and HODFC control schemes for the closed-loop system behavior are compared. From the performance comparisons, the robust HODFC control system yields favorable control performance superior to that of PID and fuzzy control systems. Moreover, it not only has a learning ability similar to that of fuzzy control but also a simple control structure as PID control. View full abstract»

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    Intelligent static VAr compensator control for supply loading optimization

    Van Harmelen, G.L. ; Enslin, J.H.R.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624441
    Publication Year: 1992 , Page(s): 154 - 157

    IEEE Conference Publications

    A digitally adaptive static Var compensator (SVC) controller for supply-side loading minimization is proposed. The control scheme is based on a model reference control structure where a model (which includes its nonlinear behavior) for the thyristor controller reactor is present within the digital signal processor. This allows minimization software to use time-domain samples of three-phase line voltages and load currents to minimize the supply side loading (i.e., maximize power factor). This type of control uses the minimization of a cost function and therefore this same controller automatically also compensates for imbalance in a multiphase supply View full abstract»

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    Experience-based learning in electrical and electronic engineering: An effective and affordable approach

    Greene, J.R.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624406
    Publication Year: 1992 , Page(s): 10 - 13
    Cited by:  Papers (2)

    IEEE Conference Publications

    The author argues that extensive `hands-on' exposure is central to engineering education, and more necessary than ever in the light of superficial and alienated learning resulting from increasing abstraction and curricular overload. He urges a broader approach to the provision of experiential learning opportunities, examines a range of alternative modes of laboratory work, and attempts to articulate some principles to guide the design of laboratory programs, reporting on a number of case studies currently being undertaken at the University of Cape Town. This is a coordinated program of demonstrations, `tasks', and projects supported by the development a cost-effective set of modules with a strong emphasis on simplicity and conceptual clarity View full abstract»

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    Optimization of quality of service requirements for real-time applications using Cross Layer Design

    Sentongo, V. ; Chan, H.A.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308125
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    The evolution of the Next Generation heterogeneous Networks relies on the improved services that these networks can provide to real-time applications. Applications running on wired networks work seamlessly with the Open Systems Interconnect (OSI) protocol stack implementation. Its modularity eases functionality and improves performance of these applications. However, the channel conditions for wireless networks are constantly varying. This affects the performance of real-time wireless applications running on wireless networks. Therefore, the operation of the OSI protocol stack is not as effective as it is when used with its wired counterpart. This research paper proposes a Cross Layer Design architecture that can be used to extend the functionality of the OSI protocol stack allowing cross layer communication between non-adjacent layers of a wireless application. It proposes a means of improving end-user delay and per-user throughput of Voice over Internet Protocol (VoIP). The proposed method entails execution of cross-talk between the transport and MAC layers of the protocol stack through cross layer clients appended to each layer and controlled by a local host called a cross layer manager. View full abstract»

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    Classical conditioning implementation with realneuron networks

    Erasmus, L.D.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401545
    Publication Year: 2007 , Page(s): 1 - 7

    IEEE Conference Publications

    This paper presents a contribution to computational modelling of associative learning through classical conditioning as known in the psychology. A seven-neuron RealNeuron network model, derived from neurobiological descriptions, and its performance is presented, using multiple resolution levels with configurable modular elements at each resolution level. RealNeurons are based on the structure of a biological neuron. With the RealNeuron's simple calculations, simulations on personal computers are possible and the simulated states on the highest, intermediate and lowest levels of resolution can be calculated using standard spreadsheet software. Further, a synthesis of a complex system, using an eleven-neuron RealNeuron network and integrates two classical-conditioning functions that can adapt to a changing poison and food environment, and its performance is presented. View full abstract»

  • Freely Available from IEEE

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    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406861
    Publication Year: 2004 , Page(s): 1112

    IEEE Conference Publications

  • Freely Available from IEEE

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    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406679
    Publication Year: 2004 , Page(s): 306

    IEEE Conference Publications

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    A silicone based hydrophobic coating for high voltage insulators

    Hoch, D.A. ; Reynders, J.P. ; Macey, R.E.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624524
    Publication Year: 1992 , Page(s): 470 - 473

    IEEE Conference Publications

    The use of hydrophobic coatings as a treatment of insulators for the prevention of pollution-related flashovers is increasingly widespread. A great deal of research into the performance of these coatings has been performed worldwide and has resulted in a good understanding of the important parameters determining the field performance of these coatings. This authors discuss these parameters and present the results of the tests performed on a coating that meets these parameters. The test techniques are also presented and discussed in some detail. The important parameters influencing the field performance of a permanent silicon-based hydrophobic coating are tracking and erosion resistance, hydrophobicity recovery after dry band arcing and hydrophobicity transfer to pollution layers. Test techniques such as a salt spray system greatly accelerate any tracking and decomposition of a poorly chosen polymer. Test results indicate that this coating meets the requirements for successful field performance View full abstract»

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    Error reconstruction surfaces of non stationary Gaussian fields

    Kazakov, V. ; Medina, A. ; Rodriguez, D.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308349
    Publication Year: 2009 , Page(s): 1 - 4

    IEEE Conference Publications

    The statistical description of an optimal sampling reconstruction procedure (SRP) of non stationary Gaussian fields is given on the basis of the conditional mean rule. The non stationarity of field is determined in space, along of one axis, but not in time. A new type of the spatial covariance function of non stationary Gaussian field is suggested. A non trivial example of SRP of non stationary Gaussian field is given. The number of samples and their locations are arbitrary. We give precise calculations of the minimum mean square error reconstruction surfaces for the non stationary and stationary fields. 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

    DOI: 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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    Static VAr compensators components and design considerations

    Tyll, H.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624442
    Publication Year: 1992 , Page(s): 158 - 161

    IEEE Conference Publications

    Static VAr compensators (SVCs) in thyristor technology are presently the most economic solutions for dynamic reactive power compensation. The arrangements, components, and design criteria of conventional SVCs using thyristors are described View full abstract»

  • Freely Available from IEEE

    [Breaker page]


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406882
    Publication Year: 2004 , Page(s): 1211

    IEEE Conference Publications

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    Flexible AC transmission systems simulation and control

    Spee, R. ; Zhu, W.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624419
    Publication Year: 1992 , Page(s): 65 - 68
    Cited by:  Papers (1)

    IEEE Conference Publications

    Concepts relating to flexible AC transmission systems (FACTS) are gaining popularity for enhancing the power transfer limits as well as the stability characteristics of power systems. The authors present an overview of FACTS devices and associated nonlinear, modern control strategies. Simulation results based on the Electromagnetic Transients Program (EMTP) are presented for dynamic brakes, devices for rapid adjustment of network impedance, and subsynchronous resonance (SSR) phenomena. Emphasis is placed on power systems with geographically concentrated generation and load centers, long transmission lines, and potential for loop flow. While these are characteristics of the Western North American Power System (WNAPS), the concepts presented can readily be applied to the power system in Southern Africa View full abstract»

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    Developing a novel laboratory program in electrical engineering for first year students

    Lawrance, W.B.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    DOI: 10.1109/AFRCON.1996.562945
    Publication Year: 1996 , Page(s): 548 - 551 vol.2

    IEEE Conference Publications

    This paper describes a teaching initiative in the Department of Electrical Engineering at Curtin University of Technology. The initiative involved the development of a new laboratory program for first year engineering students with the specific aims of enhancing team work and communication skills. Action research was used to implement the new program which also focussed on cross cultural cooperation View full abstract»

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    Change-the future of the telecommunications industry

    Harker, R.A.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    DOI: 10.1109/AFRCON.1996.563067
    Publication Year: 1996 , Page(s): 1 - 6 vol.1

    IEEE Conference Publications

    A tidal wave of change is headed towards the telecommunication industry, and it will ultimately transform the economic, social and political environment for nearly every person in the world. Much of this change is being brought about by technological innovation and the information revolution-the convergence of computing, communication and information. Organisations that acknowledge and prepare for this revolution will emerge as winners. When mains electricity first became generally available many firms went out of business, the steam engine became obsolete, and suppliers of gas lighting closed their doors. Digital technology represents a similar step change for the communications and information industries. Digital technology creates homogenised, easily delivered information that is instantly convertible into whatever form the user chooses. Four primary factors are driving this change: government and regulation, competition, technology and market demand View full abstract»

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    A logic-based perspective on agent reconfiguration: Preliminary report

    Meyer, T. ; Varzinczak, I.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072131
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    We investigate the problem of maintaining and reasoning with different configurations of a logic-based agent. Given specific contexts, there may be several possible usual configurations that the agent's knowledge base can be in, and that one may want to access at different times. This can happen due to foreseeable exceptional situations one has to cater for, or different environments in which the agent may have to operate, or simply due to upgrades of the agent's initial configuration. In all these cases, there is a need for a system capable of managing possibly conflicting versions of the knowledge base and allowing the agent to switch between any two given configurations at run time. Building on Franconi et al.'s framework for propositional knowledge base versioning, here we establish the logical foundations for a general semantic-based architecture of such a system. Central to our approach is the notion of logical difference, which allows us to determine the essential pieces of information on which two given configurations of an agent differ. View full abstract»

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    The Effect of Type of Transient Voltage Suppressor on the Signal Response of a Coupling Circuit for Power Line Communications

    Hove, M. ; Sanya, T.O. ; Snyders, A.J. ; Jandrell, I.R. ; Ferreira, H.C.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072050
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)  |  Patents (2)

    IEEE Conference Publications

    The effect of the type of transient voltage suppressor (TVS) used in coupling circuits for surge protecting PLC equipment on the signal response has been studied. The study was focused at TVS devices used in both differential and common mode surge protection. It is found that the gas discharge tube (GDT) has no effect on the communication signal, whilst TVSs that operate on avalanche breakdown attenuate the signal and they also render signal dropout at a particular frequency. Metal Oxide Varistors (MOVs) behave similarly. View full abstract»

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    Multi-hop routing protocol for an intelligent transport application

    Morrison, D.W. ; Wolhuter, R.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401592
    Publication Year: 2007 , Page(s): 1 - 9

    IEEE Conference Publications

    The rapid growth of vehicular traffic in many countries around the world has caused chronic congestion of traffic networks in many cities. To manage traffic networks more effectively intelligent transport systems (ITS) are required, but these systems require a communication infrastructure to operate. The availability of communication infrastructure is often a problem, especially in third world countries. The work presented in this paper looks at how ad hoc wireless networks can contribute towards such infrastructure. Using components from existing routing protocols, an efficient tree-based ad hoc routing protocol is developed. It is also shown how this protocol can be optimised for use in a large communication network, as would be required by ITS systems. View full abstract»

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    A low-cost electric power wheelchair with manual and vision-based control systems

    Romero, B. ; Camacho, A. ; Varona, J. ; Delgado, C. ; Velazquez, R.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308554
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper presents the design, implementation and experimental platform of a low-cost intelligent wheelchair for the motor-disabled. The first prototype developed is an electric power wheelchair which cost is one third of the commercially available ones and is capable of both manual and autonomous operation. Manual operation relies on a joystick and is intended for people that, in spite of their disability, are well capable of maneuvering the wheelchair. Autonomous operation relies on a mobile robotics inspired computer vision system to navigate through corridors, halls, indoors/outdoors, among other structured environments and is indented for the severely impaired, such as the tetraplegics. Besides from being an affordable-to-everyone device, its current application is museum guidance: based on a location-aware interactive storytelling platform, the wheelchair guides the user among the museum's rooms while providing audio information. View full abstract»

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    Loss reduction in generalised multilevel converters

    Gitau, M.N. ; Konga, C.K. ; v.d.Westhuizen, J.G.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308152
    Publication Year: 2009 , Page(s): 1 - 6
    Cited by:  Papers (2)

    IEEE Conference Publications

    Capacitor-switching operations found in magnetic-less DC-DC converters lead to significant capacitor power loss while capacitor voltage unbalance leads to high peak currents in the capacitors and switches. Power loss leads to premature failure of capacitors and is inversely proportional to both capacitance and switching frequency. A given reduction in losses then requires a corresponding increase in one of these parameters. This paper will show that by increasing the size of specific capacitors, it is possible to reduce significantly switching state transition capacitor losses and voltage unbalance without the need to increase the size of the capacitor bank by the same proportion. A method to identify capacitors that will lead to significant switching transition loss reduction when their sizes are increased is proposed. 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
    DOI: 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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    Assessment of commercially available software tools for transient stability: experience gained in an academic environment

    Kaberere, K.K. ; Folly, K.A. ; Petroianu, A.I.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406777
    Publication Year: 2004 , Page(s): 711 - 716 Vol.2
    Cited by:  Papers (7)

    IEEE Conference Publications

    There are many power system simulation software tools for transient stability analysis that are commercially available today. The choice of the most adequate tool for a specific type of stability analysis is a difficult task, and is influenced by economical reasons. It is imperative that a comparative study of various tools be carried out to help users make informed decisions. This work evaluates DIgSILENT, PSS/E and PSCAD, which are commercial software tools used for digital simulation of power systems. As criteria for software assessment, the following features are investigated: (i) modelling capabilities - synchronous generator, generator saturation, transmission line representation, and external network, (ii) flexibility allowed to the user. A well known benchmark power system model from literature is used to validate the simulation results of the commercial tools. View full abstract»

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    Control for systems in the presence of actuator and sensor hysteresis

    Xinkai Chen ; Ozaki, T.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308174
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper studies the output control for a linear plant containing uncertain hysteresis nonlinearities both in actuator and sensor devices, where the hysteresis is represented by Prandtl-Ishlinskii model. A new adaptive control scheme is developed to compensate the uncertainties in the plant, the actuator and the sensor, and to generate an estimate of the plant output. The proposed control law ensures that all the signals in the closed-loop system are uniformly bounded. Furthermore, asymptotic zero tracking of the error between the estimated output and the desired output is guaranteed. The effectiveness of the proposed algorithm is shown by computer simulation. View full abstract»

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    Reducing fuel consumption and CO2 emission by properly selecting the parameters for pool heating

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

    Volume: 2
    DOI: 10.1109/AFRCON.2002.1159973
    Publication Year: 2002 , Page(s): 571 - 577 vol.2

    IEEE Conference Publications

    Traditional pool heating systems have been designed to keep the temperature water constant or within a range throughout the day without a proper knowledge of when should the heating process be started and for how long. This may not be the most efficient heating method and the cost of operation may be quite high. It is not necessary to maintain the water temperature above the minimum allowable temperature outside the operation time. This paper attempts to select a pool heating sequence based on the usage time and other parameters, which will maintain a temperature within the desired range during operation time and minimize losses. Different scenarios are considered and the optimum one is selected so as to have the desired temperature throughout the usage time. This also gives the exact time at which the boiler must be switched on to have the desired temperature for a given set of parameters. This will help in having a more efficient system and reduce the cost of operation as well as controlling the CO2 emission. View full abstract»

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    Reduction of cogging forces in a tubular linear synchronous motor by optimising the secondary design

    van Zyl, A.W. ; Landy, C.F.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 2
    DOI: 10.1109/AFRCON.2002.1159996
    Publication Year: 2002 , Page(s): 689 - 692 vol.2
    Cited by:  Papers (7)  |  Patents (6)

    IEEE Conference Publications

    As the permanent magnet secondary section of a linear synchronous motor passes the primary section, a cogging force is produced due to the interaction of the magnets with the steel teeth of the primary. By analysing the force wave developed and optimising the geometry of the secondary design, this cogging force can be reduced. View full abstract»

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    Customized, locally developed microwave low noise amplifiers

    Boshnakov, I. ; Howie, D.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 2
    DOI: 10.1109/AFRCON.1996.563015
    Publication Year: 1996 , Page(s): 913 - 914 vol.2

    IEEE Conference Publications

    In the competitive military market, technical specifications are still the dominant criteria when designing components for front end receiver applications. Achieving system specifications that are superior to the competitors can result in component specifications that cannot be met using standard vendor catalog components. This paper discusses the approach used for development of customized low noise amplifiers (LNAs) for such applications, and the system level advantages thereof View full abstract»

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    Circuit simulation program as a support tool in mathematical environment

    Kovacevic, D. ; Jovic, M. ; Kovacevic, A. ; Paic, V.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401533
    Publication Year: 2007 , Page(s): 1 - 8

    IEEE Conference Publications

    General circuit simulation program can be used as a problem solving support in the domain of analytic geometry. Simulated analytic curve generators create a new interdisciplinary tutorial field correlating mathematics and electronics. View full abstract»

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    Web services for remote maintenance of fieldbus based automation systems

    Wolischlaeger, M. ; Neumann, P. ; Bangemann, T.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    DOI: 10.1109/AFRCON.2002.1146842
    Publication Year: 2002 , Page(s): 247 - 252 vol.1
    Cited by:  Papers (3)

    IEEE Conference Publications

    The use of Web-based concepts in industrial automation is increasingly spreading. The paper shows motivation, concepts, prerequisites and implementation details for Web integration. The role of XML-based descriptions for mapping of fieldbus data and functions to Web technologies is described. Special attention is paid to XML-based Web services. These services are mainly used for maintenance and remote control tasks in automation systems with fieldbuses. Finally, security aspects are discussed. View full abstract»

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    Utilization of available energy resources for co-generation

    Erasmus, D.J. ; Beechey, F.W. ; Delport, G.J.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821876
    Publication Year: 1999 , Page(s): 831 - 836 vol.2

    IEEE Conference Publications

    In a competitive environment and striving to maintain the competitive edge, one should always be on the look out for continuous improvement initiatives (CIP). This paper focuses on such a CIP, which was initiated by a combination of factors consisting of different pressure groups, the need to improve energy efficiency and with the available energy resources in the form of CO gas. This lead to site measurements of available energy resources and an investigation to determine the best technical and financial option for generation or cogeneration plant at an existing operation where off-gas energy is flared View full abstract»

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    Analog coherent detection in application to high-sensitivity nonlinear junction detectors

    Gruszczynski, S. ; Wincza, K.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6071963
    Publication Year: 2011 , Page(s): 1 - 5
    Cited by:  Papers (2)

    IEEE Conference Publications

    A coherent detection technique has been utilized for the design of a high-sensitivity signal detector for the purpose of detecting nonlinear junctions. The theoretical analysis of signal reception in the presence of noise are shown. Two different approaches to the design of a NLJD are presented, and schematic diagrams of the developed detectors are shown as well as the results of measurements of received signals. High-sensitivity has been achieved and confirmed via adequate measurements shown in the paper. The developed system has been tested and proved its usefulness for the detection of nonlinear junctions embedded in common electronic devices. View full abstract»

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    A critical review of Stevens' and Sinclair's equation

    Okaekwu, E.D. ; Ade, N.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308115
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    A finite-source queuing model is very useful in determining performance equations, probability of delay of users who queue for a free server when all servers are busy. The aim of this paper is to critically examine and analyze Stevens' and Sinclair's equation to show that it is a performance equation for the probability of delay in private mobile radio (PMR) systems. We analyze such an equation mathematically and present a computational program using MATLAB. The system is an M/M/r/K/K queuing model with finite sources of traffic. Some of the basic traffic characteristics and assumptions are also reviewed. View full abstract»

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    Mesh structure adjustment in 2D simulation of VLSI super self-aligned Si bipolar transistor

    Suligoj, T. ; Biljanovic, P.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821944
    Publication Year: 1999 , Page(s): 1167 - 1172 vol.2

    IEEE Conference Publications

    The fabrication process of a high-speed, deep-trench, double polysilicon super-self-aligned silicon bipolar transistor is simulated by a 2D simulation program, assuming 0.25 μm design rules. The effect of the simulation mesh on the doping profiles of intrinsic and extrinsic transistor, deposited layers and electrical characteristics are analyzed View full abstract»

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    Application of extended Huygens' principle to scattering discontinuities in waveguide

    Geschke, R.H. ; Ferrari, R.L. ; Davidson, D.B. ; Meyer, P.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 2
    DOI: 10.1109/AFRCON.2002.1159969
    Publication Year: 2002 , Page(s): 555 - 558 vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    A recently proposed extended Huygens' principle for scattering objects in a waveguide is reviewed. This technique allows the coupling of a finite element discretisation with a quasi method of moments (MM) surface element approach. Perfectly conducting posts are considered as test cases. Implementational details are discussed and results for the conducting post are presented. View full abstract»

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    The design of low-cost modular instructional equipment in electrical and electronic engineering

    Greene, J.R.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624541
    Publication Year: 1992 , Page(s): 541 - 544
    Cited by:  Papers (2)

    IEEE Conference Publications

    The author considers some conceptual dilemmas and practical problems that arise in the attempt to develop a range of low-cost instructional apparatus with which to support a program to enrich the undergraduate electrical and electronic engineering curriculum. He illustrates these by specific examples drawn from a program under way at the University Cape Town and reports informally on some of the results to date View full abstract»

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