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IEEE AFRICON. 6th Africon Conference in Africa,最新文献

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Laboratory study of long, low current power frequency arcs: initial results 长、低电流工频电弧的实验室研究:初步成果
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1159986
A. Britten, R.E. Kohimeyer, M.E. Mathebula
{"title":"Laboratory study of long, low current power frequency arcs: initial results","authors":"A. Britten, R.E. Kohimeyer, M.E. Mathebula","doi":"10.1109/AFRCON.2002.1159986","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1159986","url":null,"abstract":"The paper describes the quenching behaviour of physically long, low current, medium voltage (1-20 kV) 50 Hz arcs. The circuit devised to generate the arcs is described, together with the parameters of the multi-tap reactor used to limit the prospective short-circuit currents. The results presented include examples of the voltage-time waveforms and the dynamic volt-current characteristics. The latter characteristics are compared with those reported by Cobine. Initial criteria are proposed for predicting arc stability or quenching; these are based on the excursions of the volt-time characteristic towards the static load line. The need for further analysis of the Eskom data is stressed.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115716326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Neural network implementation on a FPGA 神经网络在FPGA上的实现
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1146859
Y. Chen, W. D. du Plessis
{"title":"Neural network implementation on a FPGA","authors":"Y. Chen, W. D. du Plessis","doi":"10.1109/AFRCON.2002.1146859","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1146859","url":null,"abstract":"This work implemented a feedforward neural network on a FPGA (field programmable gate array). A study was conducted to find the minimum precision required to maintain a recognition rate of at least 95% for two characters within an optical character recognition application. To reduce the circuit size, the bit serial architecture was realised to perform the arithmetic operation. This resulted in an optimal use of the FPGA resources.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115812090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 30
Performance evaluation of dynamic bandwidth allocation scheme for VBR video streaming in ATM networks ATM网络中VBR视频流动态带宽分配方案的性能评价
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1146843
M. Ashibani, D. Mashao, B. Nieya, R. Sewusenkar
{"title":"Performance evaluation of dynamic bandwidth allocation scheme for VBR video streaming in ATM networks","authors":"M. Ashibani, D. Mashao, B. Nieya, R. Sewusenkar","doi":"10.1109/AFRCON.2002.1146843","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1146843","url":null,"abstract":"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.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"165 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122765875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
Power and spectral efficiency of a family of constant-envelope root-of-unity filtered complex spreading sequences in WCDMA non-linear power amplification WCDMA非线性功率放大中一类恒定包络单位根滤波复扩频序列的功率和频谱效率
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1146869
L. Linde, F. E. Marx, W.R. Malan
{"title":"Power and spectral efficiency of a family of constant-envelope root-of-unity filtered complex spreading sequences in WCDMA non-linear power amplification","authors":"L. Linde, F. E. Marx, W.R. Malan","doi":"10.1109/AFRCON.2002.1146869","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1146869","url":null,"abstract":"This paper compares the spectral and power efficiency of a new multidimensional modulation strategy, employing a class of constant-envelope root-of-unity (CE-RU) filtered complex spreading sequences, with conventional Nyquist filtered QPSK modulated CDMA employing binary spreading sequences in nonlinear power amplification. The comparison is based on complementary cumulative probability density function peak-to-average power ratio (CCDF-PAPR) measurements, as well as the amount of spectral regrowth experienced when the power amplifier is driven close to the so-called 1 dB saturation point. Simulation as well as hardware results are presented to illustrate the superiority of the new complex-spreaded multi-dimensional WCDMA modulation schemes over conventional methods in terms of spectral and power efficiency in the presence of nonlinear power amplification.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124802737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
A novel DC-DC converter for low voltage ratio conversion 一种新型的低电压比转换DC-DC变换器
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1160003
R. van der Linde, I. Hofsajer, J. A. Ferreira
{"title":"A novel DC-DC converter for low voltage ratio conversion","authors":"R. van der Linde, I. Hofsajer, J. A. Ferreira","doi":"10.1109/AFRCON.2002.1160003","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1160003","url":null,"abstract":"A new DC-DC converter topology for low voltage ratio conversion is presented. The standard boost converter is the topology of choice for low voltage ratio conversion applications where galvanic isolation is not a requirement. The standard boost has low switch utilization and poor efficiency, especially at high current and high switching frequencies. The new topology presented incorporates the principle of an autotransformer in order to reduce the stress on the switching devices. The operating modes of the converter and design equations are presented. The new converter is compared with the standard boost converter.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125061717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Program for pH and conductivity measurements and determination of salt concentration in the ion exchange process for desalination of water 海水淡化用离子交换过程中pH值和电导率测量及盐浓度测定程序
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1146816
N. Dube, R. Tzoneva
{"title":"Program for pH and conductivity measurements and determination of salt concentration in the ion exchange process for desalination of water","authors":"N. Dube, R. Tzoneva","doi":"10.1109/AFRCON.2002.1146816","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1146816","url":null,"abstract":"Procedures, algorithms and programmes for acquiring of pH and conductivity measurements for input and output flows of the cation load column and for calculation of the ion exchange process input and output variables are described. The programmes are a part of a developed system for monitoring and control of an ion exchange pilot plant at Peninsula Technikon, Cape Town.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"109 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122111966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Modelling of power plants based on gasifier/gas turbine technologies 基于气化炉/燃气轮机技术的电厂建模
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1160016
A. Cano, F. Jurado, J. Carpio
{"title":"Modelling of power plants based on gasifier/gas turbine technologies","authors":"A. Cano, F. Jurado, J. Carpio","doi":"10.1109/AFRCON.2002.1160016","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1160016","url":null,"abstract":"The olive tree in Spain can generate large quantities of by-product biomass suitable for gasification. Gasification technologies under development would enable these fuels to be used in gas turbines. Biomass conversion to a clean essentially ash-free form, usually by gasification and purification, is necessary to obtain high efficiency. This paper reports results of detailed full-load performance modelling of cogeneration systems based on gasifier/gas turbine technologies.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131466823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Effect of channel coding on the performance of spatial watermarking for copyright protection 信道编码对版权保护空间水印性能的影响
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1146824
H. Rughooputh, R. Bangaleea
{"title":"Effect of channel coding on the performance of spatial watermarking for copyright protection","authors":"H. Rughooputh, R. Bangaleea","doi":"10.1109/AFRCON.2002.1146824","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1146824","url":null,"abstract":"We present a spatial-domain-watermarking scheme for data hiding and copyright protection of still images using the attack characterization approach and demonstrate the effect that the application of channel coding has on the watermark detection performance. The scheme uses techniques such as direct sequence spread spectrum modulation, perceptual analysis and diversity to maximize the robustness of the watermark while keeping it imperceptible. Furthermore, Bose-Chaudhuri-Hocquenghem (BCH) block codes and turbo codes are used to provide error protection against attacks in the watermark channel. Simulation results are provided to demonstrate the improved performance when the proposed approach is implemented with and without channel coding. The superiority of turbo codes against BCH block codes is demonstrated and some constraints involving the application of these codes to watermarking are also discussed.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121081632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 12
Analysis of factors contributing to unexplained transmission line faults on a high voltage transmission network 高压输电网输电线路故障原因分析
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1159988
H. Bekker, D. Hoch
{"title":"Analysis of factors contributing to unexplained transmission line faults on a high voltage transmission network","authors":"H. Bekker, D. Hoch","doi":"10.1109/AFRCON.2002.1159988","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1159988","url":null,"abstract":"This paper describes the results of an investigation into various fault mechanisms that may occur on the South African high voltage network. A large percentage of the recorded faults are often attributed to unknown causes. The analysis of the fault data presented in this paper indicates that many of these faults may be ascribed to known fault mechanisms. Time of day analysis coupled with time of year analysis is shown to be a useful tool in ascribing probable causes to these faults. Case studies for three particular lines are presented.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129509318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
The prediction of insulator leakage currents from environmental data 利用环境数据预测绝缘子泄漏电流
IEEE AFRICON. 6th Africon Conference in Africa, Pub Date : 2002-10-02 DOI: 10.1109/AFRCON.2002.1159978
W. Vosloo, J. Holtzhausen
{"title":"The prediction of insulator leakage currents from environmental data","authors":"W. Vosloo, J. Holtzhausen","doi":"10.1109/AFRCON.2002.1159978","DOIUrl":"https://doi.org/10.1109/AFRCON.2002.1159978","url":null,"abstract":"The leakage currents of various insulators were monitored together with environmental data at a coastal test site. In addition the daily maximum surface, conductivity was measured. In this paper it is shown how, using multiple regression, the leakage current can be predicted from the measured weather and environmental parameters.","PeriodicalId":185871,"journal":{"name":"IEEE AFRICON. 6th Africon Conference in Africa,","volume":"338 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133981431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 16
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