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    Experiences in data collection for the training of an automatic speech recognizer in Sepedi

    Manamela, M.J.D. ; Botha, E.C.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    DOI: 10.1109/AFRCON.2002.1146866
    Publication Year: 2002 , Page(s): 377 - 381 vol.1

    IEEE Conference Publications

    This paper reports on the process, experiences and statistics of collecting Northern Sotho (Sepedi) telephone speech data for the training of an automatic speech recogniser. A toll-free telephone speech recording platform was used for the data collection. An analysis of the collected speech data together with observations made during supervised calls are included before discussing preliminary results. View full abstract»

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    On the design of the feed horns for the karoo array telescope dish antennas

    Lehmensiek, R. ; Theron, I.P.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401546
    Publication Year: 2007 , Page(s): 1 - 5
    Cited by:  Papers (1)

    IEEE Conference Publications

    This paper describes the design of the feed horns for the Karoo array telescope (KAT) experimental prototype dish. The feed horn is a dual polarized circular horn with a linearly polarized circular pattern operating from 1414 to 1670 MHz. The horn is excited with a quad-ridged ortho-mode transducer (OMT). 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»

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    Micro-controller based Internet phone

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

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406680
    Publication Year: 2004 , Page(s): 307 - 311 Vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

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

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    The application of fuzzy logic for the solving of conflicts in the dispositional tasks of a railway traffic control center

    Heray, T. ; Rozsa, G. ; Koczy, L.T. ; Tompe, I.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308167
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    The paper considers a railway timetable related problem in a simplified form, generated by the delay of one or several incoming trains at a given station. Usually there are connecting trains in the timetable, especially in up to date periodic timetables and thus incoming delays might indicate the necessity of introducing a delay with connecting outgoing trains. A hierarchical fuzzy rule base is applied in order to determine the optimal outgoing delay, taking also usual restrictions into consideration. Three examples are shown. View full abstract»

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    A survey of Wireless Sensor Network testbeds

    Steyn, L.P. ; Hancke, G.P.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072072
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (2)

    IEEE Conference Publications

    During the past decade research in Wireless Sensor Networks has drawn heavy interest. For researchers to verify their research a testbed is an extremely valuable tool. This paper presents a survey documenting a selection of the best testbeds that have been developed for WSN evaluation. Laboratory testbeds and real world deployments are discussed and future work to be done on WSN testbeds is proposed. View full abstract»

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    Transient thermal analysis using both lumped-circuit approach and finite element method of a permanent magnet traction motor

    Chin, Y.K. ; Staton, D.A.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406847
    Publication Year: 2004 , Page(s): 1027 - 1035 Vol.2
    Cited by:  Papers (8)

    IEEE Conference Publications

    This work presents the transient thermal analysis of a permanent magnet (PM) synchronous traction motor. The motor has magnets inset into the surface of the rotor to give a maximum field-weakening range of between 2 and 2.5. Both analytically based lumped circuit and numerical finite element methods have been used to simulate the motor. A comparison of the two methods is made showing the advantages and disadvantages of each. Simulation results are compared with practical measurements. View full abstract»

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    ADSL capacity in a network environment

    van Wyk, J.H. ; Linde, L.P.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    DOI: 10.1109/AFRCON.2002.1146840
    Publication Year: 2002 , Page(s): 233 - 238 vol.1

    IEEE Conference Publications

    The capacity for an asymmetric digital subscriber line (ADSL) system is determined in a network environment, including other typical services, such as ISDN, high-bit-rate DSL (HDSL) and E1 leased lines. Additive white Gaussian noise (AWGN), near-end crosstalk (NEXT) and far-end crosstalk (FEXT) are included as noise sources. View full abstract»

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    Telecommunications sector reforms in Mauritius

    Rughooputh, H.C.S. ; Rughooputh, S.D.
    Africon, 1999 IEEE

    Volume: 1
    DOI: 10.1109/AFRCON.1999.820858
    Publication Year: 1999 , Page(s): 361 - 364 vol.1

    IEEE Conference Publications

    Converging technologies in the delivery of information promises more and more new services. This paper presents and discusses the broad policy issues of the Government of Mauritius on the formulation of the required strategies for the development of the telecommunication sector in Mauritius over the coming decade View full abstract»

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    The switched reluctance motor drive for distributed generation

    Humiston, T. ; Pillay, P. ; Faiz, J.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821845
    Publication Year: 1999 , Page(s): 669 - 674 vol.2
    Cited by:  Patents (1)

    IEEE Conference Publications

    Deregulation in the US power industry is the driving force behind distributed generation. Rural electrification in developing countries is providing additional impetus for the development of these technologies. High speed gas turbine generators have advantages of cost effectiveness, reliability, high power density, low maintenance and offer an efficient solution for distributed generation. The switched reluctance machine is a robust machine technology suited for efficient operation with the gas turbine as a shaft coupled high-speed generator View full abstract»

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    Hybrid concatenated super-orthogonal space-time trellis codes applying iterative decoding

    Oluwafemi, I.B. ; Mneney, S.H.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6071975
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    Hybrid concatenated code is a combination of parallel and serial concatenated codes. In this paper, two hybrid concatenated super-orthogonal space-time trellis code (SOSTTC) applying iterative decoding is proposed for flat fading channels. The encoding operation is based on the concatenation of convolutional codes, interleaving and super-orthogonal space-time trellis codes. The first concatenated scheme consists of a serial concatenation of a parallel concatenated convolutional code with a SOSTTC while the second consist of parallel concatenation of two serially concatenated convolutional and SOSTTC codes. The decoding of these two schemes is described and their bit error rate (BER) and frame error rate (FER) performance evaluated by computer simulation in Rayleigh fading channels. The proposed topologies are shown to perform better than existing concatenated schemes with constituent code of convoluntional and space time codes in literatures. View full abstract»

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    Studying the impact of mutual coupling on distance protection relays using a real-time simulator

    Pillay, K.R. ; Rigby, B.S.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072015
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper examines the impact of mutual coupling between parallel transmission lines on the performance of distance protection relays using hardware-in-loop connection of actual relays on a real-time simulator. The results confirm the extent of the likely reach errors in a distance protection scheme in a practical field example, and demonstrate the need to carefully consider mutual coupling effects when designing distance protection schemes in parallel-line topologies. 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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    Performance evaluation of dynamic bandwidth allocation scheme for VBR video streaming in ATM networks

    Ashibani, M. ; Mashao, D. ; Nieya, B. ; Sewusenkar, R.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    DOI: 10.1109/AFRCON.2002.1146843
    Publication Year: 2002 , Page(s): 253 - 258 vol.1

    IEEE Conference Publications

    In this paper, we study the problem of bandwidth allocation for ATM network loaded with real-time VBR compressed video traffic. The compressed video traffic is highly bursty in nature as a result of encoding technique and shows time-variant statistical characteristics due to scene changes. These characteristics make it more difficult to manage network recourses and can cause a significant reduction in network utilization. Our proposed scheme adjusts the allocated bandwidth at regular intervals using a multilayer compressed video in the context of congestion control. The dynamic bandwidth allocation scheme adds and drops layers of the video stream during a renegotiation process to react to congestion on very short timescales. Our simulation results show a significant improvement on the performance of the proposed dynamic bandwidth allocation scheme compared with traditional static bandwidth allocation schemes, and also offers several advantages over static bandwidth allocation schemes including it removes the need of accurate traffic parameters declaration by users at call setup phase, it is valid for a wide variety of traffic sources; and it adapts quickly to the variation of traffic sources with small renegotiation intervals. View full abstract»

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    Radio frequency identification (RFID) based conference registration system

    Nordier, L.J. ; Sinha, S.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401594
    Publication Year: 2007 , Page(s): 1 - 7

    IEEE Conference Publications

    For the registration process at a conference to be successful, a delegate's information needs to be verified quickly and accurately. In this paper, a system using external radio frequency identification devices (RFID) to bridge the gap between digital information and user requirements at a conference, is described. The system presented in this paper is divided in two subsystems, a registration subsystem and a presentation subsystem. These subsystems are written in C++ and use a connection module, to connect to an external MySQL database, written in C. View full abstract»

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    Induced currents on optical fibre cables installed in high voltage transmission line environments

    Khan, M.F. ; Hoch, D.A.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 2
    DOI: 10.1109/AFRCON.2002.1159982
    Publication Year: 2002 , Page(s): 623 - 628 vol.2

    IEEE Conference Publications

    Specialized fibre optic cables may be installed by suspending the cables from transmission line towers such that they are situated under the high voltage conductors in an outdoor environment. Long term accumulation of wind-borne pollutants followed by periods of wetting may result in leakage currents flowing axially along the optical fibre cables. Under certain severe conditions, small arcs may form on the surface of the cable. The objective of this paper is to present two simulation processes that may be used to determine these leakage currents and compare the predicted values with experimentally determined values. The effects of system voltage, attachment point of the cable at the tower and span length on the magnitude of the leakage currents have all been investigated. The feasibility of using these models to predict dry-band arcing on these cables was also determined. View full abstract»

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    One-step commutation in voltage source inverters using pulse wire sensor based current sign detection

    Krauss, S. ; Hofmann, W.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401638
    Publication Year: 2007 , Page(s): 1 - 8
    Cited by:  Papers (1)

    IEEE Conference Publications

    The dead-time effect, known as one of the basic problems in dc/ac and ac/ac power conversion, has been investigated over a long period. Varying methods based on the elimination, respectively the reduction of the dead-time effect were proposed over the last years. The main idea, beside the reduction of the semiconductor switching times, is to compensate the impact by adding the averaged dead-time error-voltage to the reference voltage. A more feasible approach is based on the knowledge of the according phase current polarity, whereas only those semiconductors are active switched, which are able to conduct the current in the actual direction. The resulting commutation strategy, known as one-step commutation, promises appreciable improvements concerning the quality of current and voltage waveforms. Beside conventional current measurement methods, a novel robust current sign detection approach, based on pulse wire sensors is presented in this paper. A first implementation of the measuring strategy is demonstrated, taking a common voltage source inverter, controlled by a standard space vector modulation and an one-step commutation algorithm in a simulation environment. View full abstract»

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    Leakage currents on lightly polluted 275 kV glass disc insulator strings in conditions of light wetting

    Bologna, F.F. ; Britten, A.C. ; Watridge, G. ; Stevens, D.J. ; Grigordakis, G.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821859
    Publication Year: 1999 , Page(s): 739 - 742 vol.2

    IEEE Conference Publications

    The research described here forms part of a larger study into the underlying reasons for a significant number of unexplained flashovers on Eskom's 220, 275 and 400 kV lines. Deductions made so far suggest that the flashovers could be the result of the combined effects of light wetting, light pollution and condensation on glass insulator strings. To evaluate this hypothesis further, leakage currents flowing on naturally polluted 275 kV glass cap and pin insulator strings (I and Vee) were monitored for about a year on a test tower in Highveld ambient conditions. The currents remained below 1 mA for most of the time, but were found at times to increase during periods when the relative humidity exceeded 75 to 80%. No flashovers occurred, but the leakage current patterns observed provide new insights into the possible mechanisms which could lead to flashover in low pollution, light wetting conditions View full abstract»

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    Auto correlation on ultrasonic Doppler signals for pregnancy determination in sheep

    Hertzog, P.E. ; Jordaan, G.D.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406654
    Publication Year: 2004 , Page(s): 173 - 178 Vol.1

    IEEE Conference Publications

    Knowing the reproductive status of his animals (sheep in the case of this project) is of utmost importance to the modern farmer. Decisions concerning the management of the flock are influenced by knowledge of the percentage of animals that are pregnant at any specific time. The aim of the project was to gain knowledge for the development of an instrument that is affordable and with which a farmer can do pregnancy determination himself, thereby enabling him to make the correct management decisions. Experimental data were obtained from pregnant Dorper ewes with the aid of a portable Doppler instrument. By using real data as input, simulations of correlation and auto correlation were done in MathCAD. In the simulations, known levels of noise were added to the Doppler signals. Satisfactory results were obtained from the simulations of auto correlation, which led to a DSP implementation of the method. In the DSP implementation of the auto correlation method, signals with an SNR of -6.5 dB were successfully identified. It can thus be concluded that the auto correlation method can be used successfully for the detection of the fetal heartbeat in noisy ultrasonic Doppler signals View full abstract»

  • Freely Available from IEEE

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    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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    GPU-based 3D-FDTD computation for electromagnetic field dosimetry

    Nagaoka, T. ; Watanabe, S.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072180
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    Numerical dosimetry with the computational human model using the finite-difference time-domain (FDTD) method has recently been used for a safety assessment of electromagnetic field applications. However, the FDTD calculation runs very slowly and requires a large amount of computational memory. We focus, therefore, on general purpose programming on the graphics processing unit (GPGPU). We implemented the three-dimensional (3D) FDTD method on GPUs using Compute Unified Device Architecture (CUDA). In this study, we used the NVIDIA Tesla C2070 as a GPGPU board and tested the performance of FDTD computation on GPUs. The results indicated that while the single GPU/CPU speed ratio varies depending on the calculation domain, 3D-FDTD computation using a GPU requires significantly less run time than that using a conventional CPU. We confirmed that the FDTD computation on a multi-GPU is much faster than that on a single GPU, and we also found that eight GPUs can compute faster than a vector supercomputer. View full abstract»

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    Power sector in Tanzania: Performance, trends and reforms

    Mwasumbi, H.A. ; Tzoneva, R.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401511
    Publication Year: 2007 , Page(s): 1 - 7

    IEEE Conference Publications

    The United Republic of Tanzania is currently facing energy problems that have seriously affected its socio-economic development and environment. To solve these problems, the country is striving to exploit its renewable energy potential, among other efforts. This paper highlights the prevailing energy situation in Tanzania and provides a short review of potential energy resources. It then discusses current institutional efforts and capabilities in development, and commercialization of renewable energy technologies. The paper also identifies some barriers to promotion of renewable energy technologies as well as actions taken by the government of Tanzania to promote renewable energy technologies. 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 LabVIEW courseware customized for pre-college learners

    du Preez, S.J. ; Sinha, S. ; Hutton, M.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401571
    Publication Year: 2007 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    The paper details the development of a courseware for LabVIEW. LabVIEW is a graphical programming language that serves as a platform for measurements and automation. The courseware is intended to be customized for South African school leaving candidates, further referred to as pre-college learners. The courseware is aimed at authenticated remote learning (online training) as well as classroom-based facilitated training. The development is an integrated compilation of experiments based on LabVIEW and PHP/SQL (to administer and manage the learners). The courseware is developed in alignment with the outcomes proposed in the new curriculum statements for South Africa, but is also applicable to other countries, in general. View full abstract»

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    Pedagogical outlines for OLPC initiatives: A case of Ukombozi school in Tanzania

    Apiola, M. ; Pakarinen, S. ; Tedre, M.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072084
    Publication Year: 2011 , Page(s): 1 - 7
    Cited by:  Papers (3)

    IEEE Conference Publications

    One-to-one computing initiatives in developing countries have been criticized for ignoring pedagogical considerations and for lacking tight integration with the local educational context. Ukombozi primary school in Iringa, Tanzania, faced the same situation in 2009, when we received 100 laptop computers for pupils to use. Through a collaborative effort of local and foreign teachers we designed and tested a pedagogical approach which starts from the local educational context, and builds on theoretical literature and documented experiences of using one-to-one computing in the classroom. We developed student-centered, exploratory, and creative practices for classroom pedagogy, and we experimented on using individual (one-to-one) laptops as a support tool. We identified a number of challenges, too, and propose further research directions that extend one-to-one computer-assisted learning to other school subjects, also. This paper is aimed at educators who work and develop education in similar challenging environments, as well as educational technology researchers who wish to gain alternative views about pedagogical design. View full abstract»

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    Unification of perception sources for perceptive awareness automatic systems

    Fuertes, C.T. ; Russ, G.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    DOI: 10.1109/AFRCON.2002.1146849
    Publication Year: 2002 , Page(s): 283 - 286 vol.1

    IEEE Conference Publications

    In order to design automatic systems in building automation supporting the capability of perceptive awareness, three specific functions are to be met: perception of the current situation, recognition of the current situation, and preventive reaction in response to the recognised situation. This paper considers the capability of perception by analysing the way this faculty is to be handled in a perceptive awareness automatic system. Human neuroscience is taken as the basis of the perceptive awareness model, therefore, references and similarities to the way perception takes place in humans are made. View full abstract»

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    Brushless DC motor characterisation and selection for a fixed wing UAV

    Gabriel, D.L. ; Meyer, J. ; Du Plessis, F.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072087
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)

    IEEE Conference Publications

    The aim of the paper is to present a method for evaluating brushless DC motors (BLDC) for fixed wing Unmanned Aerial Vehicles (UAVs). Selection of a BLDC motor, which operates in its efficient region for a UAV platform's specifications, will affect the endurance capabilities of the UAV platform. A four-constant model is presented as a means of modelling and predicting the characteristics of BLDC motors. Further, physical testing of each motor is performed on a constructed motor test bench. Validation of the model's results is compared to physical testing. The methods presented provide a means of accurately characterising a given BLDC motor. This data can be used to design the additional components used in the UAV's propulsion system. 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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    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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    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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    Dynamic control of an electrical wheelchair on an incline

    Onyango, S.O. ; Hamam, Y. ; Dabo, M. ; Djouani, K. ; Qi, G.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308254
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    Safe mobility of the disabled is one of the major reasons for the study of electric powered wheelchairs. To achieve absolute safety - where possible accident is not attributed to by the user's inability, the wheelchair should be as easy as possible to control in nearly every kind of environment. A reliable controller can only be designed from a reliable dynamic model. In this paper, consider a 3D dynamic model of a powered wheelchair having two active hind wheels and two front passive caster wheels has been considered. The developed model takes into account dynamic situations of the wheelchair in both uphill and downhill movements as well as movements on flat surfaces. Euler Lagrange procedure has been used in the derivation of the model's equation of motion then gravitational force added. Input-output feedback linearisation has then been applied in the development of the control law used in the model. View full abstract»

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    Maximising user acceptance as the underlying strategy for the development of an interactive website for South Africa's citizens

    Van Olst, R. ; Wray, C.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6071974
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper describes the development of an interactive GIS website for the Gauteng City-Region Observatory (GCRO), using User- and Usage-centric design methodologies. User acceptance was tested with the Technology Acceptance Model (TAM) to ensure that the targeted users of the website would benefit from the information presented within the website and find the technology easy to assimilate. View full abstract»

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    A Web based interactive database and CORBA tutorial

    Falb, J. ; Radinger, W. ; Goeschka, K.M.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    DOI: 10.1109/AFRCON.2002.1146875
    Publication Year: 2002 , Page(s): 425 - 430 vol.1

    IEEE Conference Publications

    With Web based open and distance learning, students appreciate the possibility to learn and train when and where they want-even from home. Based on a database, CORBA middleware and Web frontend, we implemented an interactive database and CORBA tutorial to allow for efficient, interactive student training. It also supports the testing of the student's application in a distributed environment together with a real-life database. The students can concentrate on their main tasks and need not spend time nor effort on learning complicated tools or environment configurations. Consequently, they get familiar with complex e-commerce technologies in a convenient way. View full abstract»

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    Virtual classroom system with improved student feedback

    van der Schyff, M. ; Ferreira, H.C. ; Clarke, W.A.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406725
    Publication Year: 2004 , Page(s): 499 - 503 Vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

    Student feedback in traditional virtual classrooms is usually limited to intentional feedback. Information pertaining to the actual mental state (bored, interested, content, confused), gathered from facial expressions and gestures is lost. The paper focuses on methods to increase student feedback without placing unnecessary or excessive strain on available resources such as bandwidth, memory and processing power. The method uses indirect (facial actions from student video) and direct (answers to questions and opinions) feedback to estimate the student's state. These estimates are then used to prioritise video transmission/updating from student to teacher. An experimental system is currently being developed and implemented using the Java Multimedia Framework (JMF) View full abstract»

  • Freely Available from IEEE

    [Breaker page]


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406627
    Publication Year: 2004 , Page(s): 29

    IEEE Conference Publications

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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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    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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    A cost-sensitive approach to laboratory work for a fourth-semester course in digital modulation

    MacPherson, S. ; McLeod, M. ; Shi, S.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401561
    Publication Year: 2007 , Page(s): 1 - 7

    IEEE Conference Publications

    A set of proposed practical laboratory tasks for the final semester technician-level subject Radio Engineering 3 at the Durban University of Technology (DUT) is presented and justified. The tasks involve work with physical instruments as well as design and simulation software. A minimal instrument inventory is proposed and low-cost software options are explored. The use of student projects as a source of functional laboratory modules is described. The potential for using FPGA technology in this area is outlined. View full abstract»

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    The new subsensitive instrument-active transducers

    Molchanov, P.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821938
    Publication Year: 1999 , Page(s): 1143 - 1146 vol.2

    IEEE Conference Publications

    The new standards of transducers - active transducers (AT) have been introduced. The principle of AT theory is developed on the basis of the nonlinear charge model. A Volterra functional series is used to calculate parameters of AT. Particular attention have been devoted to the microwave AT for control applications. An experimental AT for temperature and moisture telemetering control has been described to confirm the theoretical assumptions View full abstract»

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    A four-fingered robot hand with shape memory alloys

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

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

    IEEE Conference Publications

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

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

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

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

    IEEE Conference Publications

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

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    Next-generation wireless networks: A new world, from bottom to top

    Foty, D.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401584
    Publication Year: 2007 , Page(s): 1 - 9
    Cited by:  Papers (1)

    IEEE Conference Publications

    As data content mushrooms and becomes increasingly dispersed, the demand for (and need for) bandwidth - both wired and wireless - continues to increase; however, technology has demonstrably not been up to this task. A major intellectual gap has been the attempt to address this demand via "digital thinking," in which transistors and power can be used gratuitously to overwhelm the problem; this is simply not working. Despite a number of challenges, millimeter-wave radio is slowly emerging as a unique way to transcend the "digital mindset" and address a wide variety of bandwidth challenges - by making bandwidth available without outlandish demands in complexity and power consumption. In addition to the "usual" applications, the basic nature of millimeter-wave radio offers the prospect of revolutionizing network topologies, allowing for the development of new network infrastructures - such as mesh and pseudo-neural networks. View full abstract»

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    Modelling and control of slip power recovery schemes for small hydro power stations

    Okafor, F.N. ; Hofmann, W.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406851
    Publication Year: 2004 , Page(s): 1053 - 1058 Vol.2
    Cited by:  Papers (5)

    IEEE Conference Publications

    It is well known that small hydropower stations (SHS) are characterised by wide variations in water- flow-speed due to the absence of an elaborate reservoir facility. As a result, conventional synchronous generators which are basically constant-speed constant - frequency systems are not well suited for use in such schemes. The usual problem is low efficiency arising from relatively poor control of active and reactive power flow in the system. This paper investigates the use of a class of doubly fed induction generators (DFIGs) for the energy conversion process in SHS. In contrast to the conventional DFIG employing the so-called back-to-back configuration, the proposed scheme utilises two voltage source inverters (VSI), each connected to the stator and rotor respectively. This gives rise to four degrees of freedom of control, which presents several advantages including field weakening operation and control over twice the rated speed range. Simulation studies of a 600 KW machine are presented to show the efficacy of the proposed scheme. View full abstract»

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    AfriCampus-energy management on campus

    Delport, G.J. ; Calmeyer, J.E.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821874
    Publication Year: 1999 , Page(s): 819 - 824 vol.2

    IEEE Conference Publications

    African academic institutions have an ideal opportunity to initiate energy management programmes on their campuses. AfriCampus is an energy management collaboration between all universities, technikons and secondary schools in Africa, and particular Southern Africa. The purpose of this collaboration is to establish an energy management co-operation channel by which expertise, equipment and information can be transferred View full abstract»

  • Freely Available from IEEE

    Table of contents


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406616
    Publication Year: 2004 , Page(s): i - xxii

    IEEE Conference Publications

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    On placing the reflection plane in numeric inductance calculations of thin-film superconducting structures using the method of images

    Fourie, C.J. ; Perold, W.J.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 2
    DOI: 10.1109/AFRCON.2002.1159958
    Publication Year: 2002 , Page(s): 499 - 504 vol.2
    Cited by:  Papers (2)

    IEEE Conference Publications

    Determining the inductance of thin film superconducting structures accurately is extremely important in sub-Terahertz superconducting logic circuits. For numeric analysis, both the structure and ground plane need to be sufficiently segmented. The method of images significantly reduces the number of segments, but the selection of the position of the reflection plane is critical. The influence of the position of the reflection plane on inductance is investigated, and results presented. A study of segmentation and filamentation is also made, and these results used to calculate the inductance of a complex three-dimensional structure. View full abstract»

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

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

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

    IEEE Conference Publications

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

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    The role of natural language in social information engineering

    Englmeier, K. ; Murtagh, F. ; Mothe, J. ; Pereira, J. ; Rosenberg, D.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072069
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    In this paper we present work-in-progress - a technology platform for Social Collaboration in the context of Personalized Information Extraction. In particular, we consider elements of user-centered software engineering as it converges on the development of folksonomies. Results from our work-in-progress demonstrate to what extent non-IT users can apply natural language when managing their IT-based processes addressing information integration. We concentrate on the language model that supports the development of process-related folksonomies in the context of retrieving and merging textual information from different sources concerning legal documents. Findings in our work-in-progress underpin the conjecture that the computational nature of natural language overcomes the inherent problem of ambiguity when applied in a collaboration context that the users are aware of. View full abstract»

  • Freely Available from IEEE

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    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406710
    Publication Year: 2004 , Page(s): 430

    IEEE Conference Publications

  • Freely Available from IEEE

    [Breaker page]


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406860
    Publication Year: 2004 , Page(s): 1111

    IEEE Conference Publications

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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»

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    Model predictive control of a flying capacitor converter with output LC filter for UPS applications

    Stolze, P. ; du Toit, D. ; Tomlinson, M. ; Kennel, R. ; Mouton, T.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6071966
    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (2)

    IEEE Conference Publications

    This paper presents a model predictive control strategy for a three-level flying capacitor converter with output LC filter for UPS applications. In order to reduce the calculation effort (64 different switching possibilities for one prediction step) in a first step the best one of the 19 voltage vectors is determined. After that the best switching state which delivers this voltage vector is determined regarding the flying capacitor voltage balancing and the switching effort, making use of a hysteresis-based algorithm. A disturbance observer is used to estimate the output currents of the LC filter which are normally not measured. The proposed principle can be easily extended to flying capacitor converters with more than three voltage levels. View full abstract»

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    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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    Propagation measurements and modeling for terrestrial line-of-sight links at 19.5 GHz

    Naicker, K. ; Mneney, S.H.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406640
    Publication Year: 2004 , Page(s): 95 - 100 Vol.1
    Cited by:  Papers (2)

    IEEE Conference Publications

    With the rapid growth of the telecommunications market, the hunger for greater bandwidth and higher data rates has become unrelenting. Together with the congestion of the frequency bands below 12 GHz, frequency planning has become increasingly difficult. The use of the upper portion of the k-band for terrestrial communication systems is inevitable due to the better spectrum availability of this frequency region and the inherent ability to provide higher data rates. The frequency band from 18 GHz to 20 GHz has been identified as a suitable candidate for short-haul line-of sight (LOS) links. As a consequence, a 6.73 km terrestrial LOS link centered at 19.5 GHz has been recently established between the Howard College and Westville campuses of the University of KwaZulu-Natal (UKZN). In this paper, the research into the modeling and measurement of the proposed LOS link is discussed View full abstract»

  • 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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    Design of locomotive location indicator communication system

    Oranye, N. ; Masupe, S. ; Chuma, J.M. ; Sebusang, S.E.M.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406896
    Publication Year: 2004 , Page(s): 1269 - 1273 Vol.2

    IEEE Conference Publications

    Locomotive transportation plays an important role in Botswana. It plays a critical role in the transportation of people, livestock, raw materials and goods. It now faces new challenges in a highly competitive economy in the form of efficiency and the onslaught from road trains, the latter of which often use a subsidised, government funded road network. Whilst perhaps the national railway operator cannot do much to change the advantage enjoyed by the road hauliers, it is on the operational efficiency side that much can be gained by the deployment of appropriate, cutting-edge technical solutions. One operational problem that Botswana Railways (BR) and others using similar technologies for locating presence on site and positions of their trains and cargo, typically the DC Track Circuit and the Axle Counter System respectively, is that the power supply equipment associated with the operations of the two systems is located on unsecured environments, and thus susceptible to vandalism and theft. Vandalism and theft of this equipment on the BR network has escalated over the years, seriously undermining the efficiency and throughput of the network, whilst equally exposing the cargo to potential loss. This work presents a new scheme of locating the positions of locomotives by using Global Positioning Systems (GPS) to track, in real-time, the location of vehicles and equipment The scheme proposes two GPS receivers placed on the train, one on the engine and the other on the last carriage. The receivers placed on the train transmit information back to a control room on an interactive graphical display unit. The results of the simulated communications system will be presented. View full abstract»

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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»

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    Using parallel-interconnected Viterbi decoders to correct insertion/deletion errors

    Swart, Theo G. ; Ferreira, H.C. ; dos Santos, M.P.F.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406688
    Publication Year: 2004 , Page(s): 341 - 344 Vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

    We present a new insertion/deletion correction scheme for standard convolutional codes that makes use of multiple interconnected parallel Viterbi decoders. Whenever an insertion or deletion error occurs, the connections between different Viterbi decoders ensure that decoding proceeds from the decoder that is in synchronization. In this way, a larger Viterbi decoder is created that can correct insertion and/or deletion errors by extending the Viterbi algorithm to encompass all parallel decoders. Further, we show how the performance can be improved by inverting certain bits during the encoding of the convolutional codes, thus lowering the frequency of occurrence for repeating sequences, which is detrimental to synchronization View full abstract»

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    Design flow for CMOS based Class-E and Class-F power amplifiers

    Bozanic, M. ; Sinha, S.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308187
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    This paper presents the design flow for an integrated power amplifier. The flow is presented as a software routine. For a given set of amplifier specifications and CMOS process parameters, the routine computes the passive component values for a class-E or class-F based power amplifier. The routine includes the matching network for standard impedance loads. The routine also provides its user with a spiral inductor search algorithm, which can be used to generate layouts of inductors with Q-factors optimised at a desired frequency. For a typical power amplifier design case where several amplifiers are designed for application over different channels, the routine presented in this paper contributes by streamlining the design flow. The operation of the software routine was demonstrated by simulations in Austriamicrosystems 0.35 mum single-supply process for a 14 dBm, 2.4 GHz power amplifier design. View full abstract»

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    A frame-based object relational expert database system

    Rattanaprateep, C. ; Chittayasothorn, S.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401490
    Publication Year: 2007 , Page(s): 1 - 7
    Cited by:  Papers (2)

    IEEE Conference Publications

    An expert database system is an expert system which is developed on databases using DBMS technology to manage facts and rules. Frame-based expert systems are widely used as the knowledge representation for such expert systems with large knowledge bases. Many systems have the ability to connect to external databases. Facts stored in databases can be loaded into expert system's knowledge base and inference is performed by the inference engine of the expert system. In many cases, such external facts are required several times for each inference. Thus, a lot of communication traffic takes place. This research work present the design and implementation of a frame-based object-relational database system which has a tight coupling between the expert system and the external knowledge base. The external knowledge base also use frame as its knowledge representation. More over, it has its own inference engine so that inference can be perform on the knowledge base side and the results, not only simple facts, are sent back to the expert system for further inference. A medical consultation system is used as an illustrated example an Oracle lOg object relational DBMS is used as the database platform. 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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    Practical evaluation of voltage unbalance at a distribution transformer based on 50 Hz negative sequence active power

    Seiphetlho, T. ; Rens, J.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072129
    Publication Year: 2011 , Page(s): 1 - 4
    Cited by:  Papers (1)

    IEEE Conference Publications

    The paper investigates the measurement and propagation of voltage unbalance at a distribution transformer. The relations between unbalance factors in voltage and current with the direction of negative sequence fundamental frequency active power are investigated. The goal is to evaluate possible applications of the principles derived by a simulation study in the practical assessment of how much variation in voltage asymmetry is contributed at an interconnection due to loading and how much is due to supply conditions. It is shown that a practical assessment of voltage asymmetry is not straightforward. View full abstract»

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    Comparison of the communication time of a high gain versus a low gain monopole-like low profile antenna on a 3-unit CubeSat

    Khotso, P.A. ; Lehmensiek, R. ; van Zyl, R.R.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072146
    Publication Year: 2011 , Page(s): 1 - 4

    IEEE Conference Publications

    This paper investigates the effect of the antenna pattern on the communication time between a ground station and a low earth orbit satellite with passive attitude control, i.e. the antenna is nadir pointing. Two low profile antennas that fit on a 3-unit CubeSat are considered, namely a high gain patch and a low gain monopole-like patch antenna. The communication system is for high speed S-band communication. View full abstract»

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    Thin FC film for sidewall passivation in SCREAM process for MEMS

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

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

    IEEE Conference Publications

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

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    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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    Increasing value of projects by leveraging limited capacity through the application of the Theory of Constraints

    Viljoen, P.J.
    Africon Conference in Africa, 2002. IEEE AFRICON. 6th

    Volume: 1
    DOI: 10.1109/AFRCON.2002.1146888
    Publication Year: 2002 , Page(s): 493 - 498 vol.1

    IEEE Conference Publications

    This paper introduces the concepts of the Theory of Constraints as developed by Dr. E. M. Goldratt and others. When applied to a portfolio of projects, the value that an organisation realises from successful delivery can be maximised. A new value metric is introduced that effectively accounts for the flow of money in different time periods. An approach to portfolio management that strives for maximising organisation performance, given limited organisational capacity, is also introduced. Critical Chain project scheduling and synchronising projects around the schedule of a heavily loaded (drum) resource are used as the methodology of finite capacity management that enables leveraging value with scarce resources. A new set of buffers is introduced to enable the integration of portfolio management and Critical Chain scheduling. 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»

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    Rapid spectrum sensing with multiple antennas for cognitive radio

    Pu Wang ; Jun Fang ; Ning Han ; Hongbin Li
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072049
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    We consider the problem of detecting a primary user in a cognitive radio network by employing multiple antennas at the cognitive receiver. In vehicular applications, cognitive radios typically transit regions with differing densities of primary users. Therefore, speed of detection is key, so detection based on a small number of samples is particularly advantageous for vehicular applications. Without assuming any prior knowledge of the primary user's signaling scheme, the channels between the primary user and the cognitive user, and the variance of the noise seen at the cognitive user, a generalized likelihood ratio test (GLRT) is developed to detect the presence/absence of the primary user. Asymptotic performance analysis for the proposed GLRT is also presented. Performance comparison between the proposed GLRT and other existing methods such as the energy detector and several eigenvalue-based methods under the condition of unknown or inaccurately known noise variance is provided. Our results show that the proposed GLRT exhibits better performance than other existing techniques, especially when the number of samples is small, which is particularly critical in vehicular applications. View full abstract»

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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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    Measuring SET effects in a CMOS operational amplifier using a built-in detector

    Espinosa-Duran, J.M. ; Velasco-Medina, J. ; Huertas, G. ; Velasco, R. ; Huertas, J.L.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401472
    Publication Year: 2007 , Page(s): 1 - 7
    Cited by:  Papers (4)

    IEEE Conference Publications

    This paper studies the effects produced by radiation single event transient (SET) injected in the transistors of a custom operational amplifier, in order to evaluate their sensitivity to the radiation transient faults. A BID (built-in detector), was included in the circuit in order to amplify and detect the SETs effect. The circuit was designed using a non-rad- hard AMS-CMOS 0.8 mum process. In this case, simulation results allow the identification of the operational amplifier most sensitive transistors and the operating conditions during which the worst effects in the operational amplifier response were produced. 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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    Secure Digital Data Collection in household surveys

    Hattas, M. ; Eloff, M.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072142
    Publication Year: 2011 , Page(s): 1 - 6

    IEEE Conference Publications

    Digital Data Collection in South Africa is continuously evolving as technology and infrastructural networks gain momentum with respect to its development. In-field data collection is critical for any national government department who is mandated to supply the country and the international community with official data. The paper aims to illustrate the methods used by Statistics South Africa (StatsSA) in collecting household data using a digital collection process. The Quarterly Labour Force Survey (QLFS) and Dwelling Frame Project's are the primary focus areas of implementation. The paper further focuses on the background to the technology, its usage, problems encountered, lessons learnt, software/ questionnaire development, and more importantly the security issues around the collection of the data. View full abstract»

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    Evaluation of quality concepts influencing a manufacturing environment in South Africa

    Erasmus, P. ; van Waveren, C.C.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401566
    Publication Year: 2007 , Page(s): 1 - 9

    IEEE Conference Publications

    This research article evaluates the influence from quality concepts and tools in a manufacturing environment on parameters that may affect future design and development of products in the same company. It attempts to establish how quality results can be utilised to determine the level of quality control tools such as quality function deployment and concurrent engineering in a company that designs for manufacture. By establishing links from quality results and customer requirements, the research determines what critical quality tools are necessary to determine the capability of manufacturing an item without the use of excessive planning resources. Research was performed on four distinct subject matters namely design, manufacture, quality control and concurrent engineering and the results of the research was implemented in a design and manufacturing environment with the purpose of establishing direct links between quality control results and design parameters to increase future development. The research also establishes, by means of a questionnaire, the level of certification to quality standards of South African manufacturing companies, while determining their knowledge in regard to quality, its tools and concepts, as well as the level to which these are implemented and utilised in manufacturing entities. View full abstract»

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    Call-level performance evaluation and QoS provisioning in cognitive radio networks

    Mihov, Y.Y. ; Tsankov, B.P.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072183
    Publication Year: 2011 , Page(s): 1 - 5

    IEEE Conference Publications

    This paper investigates the call-level performance of a cognitive radio network for dynamic spectrum access providing multimedia service to secondary users. The serving system is modeled by a two-dimensional state-transition diagram and a novel approximate but computationally efficient analytical approach for solving its state probabilities is developed. A new precise formula for evaluation of the call dropping probability of the secondary users is derived. Channel limitation as a method for quality of service provisioning is suggested. Extensive simulation experiments are performed to validate the proposed analytical solutions. Numerical results are presented and some insightful conclusions are drawn. View full abstract»

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    A dictionary approach to fault diagnosis of analog circuits

    Marin, C.V. ; Constantinescu, F. ; Nitescu, M.
    AFRICON, 2011

    DOI: 10.1109/AFRCON.2011.6072155
    Publication Year: 2011 , Page(s): 1 - 5
    Cited by:  Papers (2)

    IEEE Conference Publications

    This paper deals with dictionary approach for single soft faults diagnosis in analog circuits. A method for selecting the optimum set of test frequencies is proposed. The first step uses circuit sensitivity analysis to choose the optimum frequency ranges. Then the optimum set of frequencies is selected using the entropy criterion. 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»

  • Freely Available from IEEE

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    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406844
    Publication Year: 2004 , Page(s): 1016

    IEEE Conference Publications

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    Securing a transmission channel between two remote computers with secure shell and implementing cryptography on smart card

    Bhatt, D.V. ; Blignaut, J.F. ; Hancke, G.P.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406698
    Publication Year: 2004 , Page(s): 377 - 382 Vol.1

    IEEE Conference Publications

    Communication plays a very important and indeed a crucial part in our daily lives. Electronic mail, data transfer, and the development of the Internet have changed the way the world communicates. As the Internet grows in popularity and therefore also in size, more and more transmissions take place, mainly because the technology is more readily available and applications have become more user friendly, allowing entry to less sophisticated users over a broad spectrum. Intertwined herewith, is the significant increase in business related use and transmission of critical data, ultimately leading to a significant increase in security risks. This has attracted and encouraged the entry of common criminals with a high level of computer based skills. Most data transfers are mainly text based, not secure and vulnerable to various forms of security risks. The open and distributed structure of the Internet has caused this major global security problem - for businesses and the individual. In the case of an individual, a security breach is localised, whereas with businesses the implications are far reaching. Leakage of intellectual property, confidential information and/or financial information could greatly harm businesses and their stakeholders. This presentation looks at a model that uses SSH for securing an insecure channel like Internet, whilst integrating smart cards for client authentication and encryption and decryption of data View full abstract»

  • Freely Available from IEEE

    Copyright


    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406607
    Publication Year: 2004 , Page(s): 0_4

    IEEE Conference Publications

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    Quality of service in telecommunications - the customer's perspective

    Afullo, T.J.O.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 1
    DOI: 10.1109/AFRICON.2004.1406641
    Publication Year: 2004 , Page(s): 101 - 106 Vol.1
    Cited by:  Papers (1)

    IEEE Conference Publications

    In today's competitive telecommunications environment, customer satisfaction is key to gaining market share. Improving service quality results in improved customer satisfaction. A telecommunications service provider's survival depends on its ability to prepare for changes in customer needs, as well as changes in regulation and technology. But the increasing expectations of customers and the introduction of many new services and technologies is making it difficult to comprehend and meet customer requirements. Therefore, while the quality of service (QoS) required by the customer is the vital input to both the service provider and the regulator, the QoS achieved and that perceived are equally important. In this paper, we highlight standard procedures for determining quality of service. Then, we present typical results for the UK and Singapore, as well as customer survey results for Botswana View full abstract»

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    Defining a project life-cycle for implementing a high-tech project in rural Southern Africa-a case study

    Bekker, M.C.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406812
    Publication Year: 2004 , Page(s): 873 - 877 Vol.2

    IEEE Conference Publications

    Bridging the gap between first world practices and third world needs remains a topic for continuous debate, research and experimentation. Although the practices of project management are deemed to be generally and universally applicable, the success rate of projects in the developing world is questionable. In South Africa the various provincial governments embarked on a programme to outsource the payment of social pensions to the aged, child support and for disabled people to private companies. The primary objectives of the outsourcing drive were to alleviate the administrative burden on departments and to replace the manual payment of pensions by means of a smart card system within close proximity of the each beneficiary's residential home. Even though the technology of smart cards is fairly mature, the introduction of this concept to a market characterised by illiteracy, limited access to automatic teller machines (ATMs) and bank accounts, high levels of corruption and where payments are mostly in rural areas, posed new challenges to project life-cycle definition and the application of the nine knowledge areas of the PMBoK (Project Management Body of Knowledge). This work provides an overview and analysis of the specific challenges facing the definition of a project life-cycle in the developing world. It focuses on the social and economic characteristics of a developing environment and indicates how project management can facilitate the introduction of high technological products and services into a developing environment. The paper is based on an actual project, which won a "High-Commend" award from the PMSA (Project Management South Africa). View full abstract»

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    Planning power system outages with decision analysis modeling

    van der Walt, T.N. ; van Waveren, C.C.
    AFRICON, 2004. 7th AFRICON Conference in Africa

    Volume: 2
    DOI: 10.1109/AFRICON.2004.1406819
    Publication Year: 2004 , Page(s): 921 - 926 Vol.2

    IEEE Conference Publications

    Within the South African electricity supplier (Eskom) the outage scheduler working in the National Control department is responsible for sanctioning planned equipment outages on the interconnected power system. Currently this decision making process is not quantified. This work investigates the possibility of quantifying the decision by using decision analysis techniques. The decision analysis process suggested by Clemens is followed. A planned the outage situation is identified and deconstructed. With the use of reliability studies the failure probabilities are calculated and used in the decision model. The model is used to calculate expected values of the decision. Sensitivity analysis is used to identify which of the variables have the biggest impact on the decision. The conclusion of This work is that decision analysis techniques could greatly assist the outage scheduler, but for it to be useful, better faultfinding needs to be done to uncover the reasons for transmission line trips. By doing this the accuracy of the decision model would be vastly improved upon. View full abstract»

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    TESPAR coded speech quality evaluation (TCSQE)

    Adar, P.O. ; Odhiambo, M.O.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308198
    Publication Year: 2009 , Page(s): 1 - 6

    IEEE Conference Publications

    Speech transmission quality measurement in cellular networks is a major indicator of performance for end-to-end quality of service standards. Many approaches have been proposed in the previous studies, but the results correlation with subjective experiments still need further optimization, especially for quality determination using languages with unique phonetic structures i.e. clicking sounds. Moreover, the evaluation test data is always a key element in order to obtain representative and consistent results. In this paper, we introduce TESPAR coding technique for the design of a new algorithm for speech (voice) quality measurement in cellular/wireless telecommunication networks. Our experiments show that the results from this algorithm correlates well with subjective experiments using a variety of speech samples. The proposed algorithm is also computationally efficient than the existing methods and is suitable for quality measurement of longer speech signals than the current 8 seconds speech test data mostly in use today. View full abstract»

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    MATLAB, LabVIEW and FPGA linear control of an inverted pendulum

    Han, Y. ; Tzoneva, R. ; Behardien, S.
    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401454
    Publication Year: 2007 , Page(s): 1 - 7

    IEEE Conference Publications

    Linearized model, pole placement and LQR linear controllers are derived for the inverted pendulum bytronic plant. Investigation of the real-time controller implementation using different PC (MATLAB/LabVIEW) and field programmable gate array (FPGA) CompactRIO (cRIO) platforms is done to prove and verify the FPGA capabilities in real-time control. The dynamic behaviour of the inverted pendulum under the same control, realized by the above various real-time platforms is obtained to be identical. 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»

  • Freely Available from IEEE

    [Front cover]


    AFRICON 2007

    DOI: 10.1109/AFRCON.2007.4401652
    Publication Year: 2007 , Page(s): c3 - c4

    IEEE Conference Publications

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

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

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

    IEEE Conference Publications

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

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    Fusion of intelligent sensor data for robot control

    Nauth, P.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308192
    Publication Year: 2009 , Page(s): 1 - 5
    Cited by:  Papers (1)

    IEEE Conference Publications

    Nowadays robots can recognize their environment in a limited way. Future robots designed for operations in a natural environment and for communicating with humans in a natural way require the fusion of data acquired from spoken words and sensory data from the surrounding area. By means of intelligent sensors for speech recognition, proximity measurement, colour measurement and image processing an intelligent robot has been developed. The robot understands the name of an object a user has told the robot to take and searches for it by means of a smart camera and other sensors. After it has found and identified the object, it grabs it and brings it to the user. View full abstract»

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    Design of a sinewave inverter for alternative energy

    Malengret, M.
    AFRICON '92 Proceedings., 3rd AFRICON Conference

    DOI: 10.1109/AFRCON.1992.624426
    Publication Year: 1992 , Page(s): 95 - 98
    Cited by:  Papers (1)

    IEEE Conference Publications

    The authors describes the principle and design criteria adopted for a small economical, portable, robust inverter used for outdoor or remote area power supply (RAPS). Sine-weighted pulse-width-modulation (PWM) techniques applied to a push-pull inverter with a front-end filter are used. The front-end filter, using a cross-coupled choke on the low 12 V side, makes it a current fed inverter and hence suitable for starting motors. The topology offers a sinusoidal flux in the main step-up transformer, and thus a good efficiency at low loads. The cost is similar to that of push-pull center tap quasi-square inverters View full abstract»

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    Some observations on time varying harmonics and inter harmonics

    Lazenby, W.H. ; Zivanovic, R.
    Africon, 1999 IEEE

    Volume: 2
    DOI: 10.1109/AFRCON.1999.821879
    Publication Year: 1999 , Page(s): 849 - 852 vol.2
    Cited by:  Papers (1)

    IEEE Conference Publications

    Today, most international standards like the IEC, the IEEE, and the SA standards make use of discrete frequencies to calculate their power quality indices, like total harmonic distortion. This paper presents the shortcoming in using these formulae. This paper also represents some possible remedies for the above mentioned shortcomings View full abstract»

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    Improving the accuracy and overall value of stator winding insulation assessments for operational generators, through laboratory based insulation research tests on stator bars

    van der Merwe, H. ; Rasekhi, P. ; Volk, N.R.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    DOI: 10.1109/AFRCON.1996.563154
    Publication Year: 1996 , Page(s): 447 - 450 vol.1

    IEEE Conference Publications

    The Technology Research and Investigations division of Eskom's Technology Group (T-R-I) is currently investigating the technical and logistical merit of performing offline quadratic-rate partial discharge tests on the stator winding insulation of its hydro- and turbo-generators. A series of laboratory based insulation research studies on stator bars have been conducted to gain a better understanding of the various partial discharge phenomena involved. Results thus far obtained from these tests have provided valuable insight into the discharge activity of operational generators View full abstract»

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    FACTS control by sampled regulator design

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

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

    IEEE Conference Publications

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

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    Education and training of microelectronic engineers: why and how?

    Joubert, T.-H. ; du Plessis, M. ; Snyman, L.W. ; Theron, E.A.
    AFRICON, 1996., IEEE AFRICON 4th

    Volume: 1
    DOI: 10.1109/AFRCON.1996.563125
    Publication Year: 1996 , Page(s): 293 - 296 vol.1

    IEEE Conference Publications

    In this paper an undergraduate training program for engineers with practical microelectronic experience is presented. The emphasis in this program is on the design of devices and integrated circuits, and the reason for this is expounded. A discussion of the incentives for producing such engineers for the South African context is also furnished View full abstract»

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    Formalizing certain tasks for processor architecture verification

    Shah, A.K. ; Al-Mazyad, A. ; Ramani, A.K.
    AFRICON, 2009. AFRICON '09.

    DOI: 10.1109/AFRCON.2009.5308179
    Publication Year: 2009 , Page(s): 1 - 4

    IEEE Conference Publications

    Present day verification is a time consuming task. With processor architecture complexity increasing by the day, managing the complete verification process has become a major challenge. Besides, a small bug in the final product may ruin all the efforts. This problem has resulted in the popularity of verification and other related technologies. For example formal verification is now considered as an important part of any verification process. Similarly other technologies and methodologies are gaining acceptance. However, despite all these tools and technologies, verification still remains the main bottleneck and challenge in the overall process for the development of a modern processor. This problem can be looked from a different angle. We believe that a proper strategy is equally important for the verification efforts to succeed. The strategy will be easier once we formalize certain aspects of the process. This paper is an attempt to formalize some of the important aspects, ideas and methodologies towards the verification of processor architecture. View full abstract»

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