2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590)最新文献_第3页

Resistive reach guidelines for impedance relay applications 阻抗继电器应用的电阻到达指南

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406800

R. Naidoo, E. Stokes-Waller

{"title":"Resistive reach guidelines for impedance relay applications","authors":"R. Naidoo, E. Stokes-Waller","doi":"10.1109/AFRICON.2004.1406800","DOIUrl":"https://doi.org/10.1109/AFRICON.2004.1406800","url":null,"abstract":"Impedance relays must accommodate all types of faults. In order to enable this, it is necessary that the correct voltage and current quantities be applied to the measuring elements. The impedance characteristics are obtained from these three-phase voltage and current measurements. The main aim is to detect the faulted phases and react appropriately based on the applied relay settings, scheme design and philosophies. The difficulty arises in the distinction between the faulted and healthy phase impedance measurements. Continuous research and development of impedance relays are in progress to improve its operating performance. Unfortunately, the impact and limitations of such improvements on the power system applications are not studied with the same vigour. As such, it is necessary to investigate the influence of network topology, power system loading, fault resistance etc. on the reach capability of impedance relays when applied to power systems. In This work, the reach capability of impedance relays is investigated. A set of resistive and reactive reach guidelines for impedance relay applications are presented. The results from the research also show that the network topology and faulted phase selection algorithms play a major role in power system healthy phase impedance measurements. New impedance ratios namely SWIR and SNIR are introduced, and the well-known system impedance ratio (SIR) is enhanced for ease of illustrating network topology and associated impedance measurement.","PeriodicalId":224116,"journal":{"name":"2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127888649","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-model reference control of an air motor 空气马达的神经模型参考控制

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406717

R. Marumo, M. Tokhi

{"title":"Neural-model reference control of an air motor","authors":"R. Marumo, M. Tokhi","doi":"10.1109/AFRICON.2004.1406717","DOIUrl":"https://doi.org/10.1109/AFRICON.2004.1406717","url":null,"abstract":"Neural networks are known for their unique properties of universal approximation. A description of a nonlinear plant in state space is obtained using a recurrent Elman network. Learning is implemented off-line with a truncated back propagation through time algorithm. Based on the neural model, a reference control strategy is implemented as a sequence of control actions computed by solving an optimisation problem iteratively. The past decade has seen an increase in research into the control of pneumatic drives. Two main reasons motivate this study: the response of pneumatic drives is slow, leading to an inability to attain set points due to high hysteresis; the dynamic model of the system is highly non linear, which greatly complicates controller design and development. Two streams of research efforts have evolved: using conventional methods to develop a modeling control strategy; adopting a strategy that does not require a mathematical model of the system. The paper presents investigations into the modeling and control of an air motor incorporating a pneumatic equivalent of the electric H-bridge. The pneumatic H-bridge has been devised for speed and direction control of the motor. The system is divided into three main regions: low speed (below 390 rev/min); medium speed (390 to 540 rev/min); high speed (540 to 680 rev/min). The system is highly nonlinear in the low speed region and hence an intelligent controller system, such as a neuro model and reference controller, is proposed","PeriodicalId":224116,"journal":{"name":"2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125601287","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: 14

Using human language technologies in aviation weather applications 在航空气象应用中使用人类语言技术

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406620

L. Butgereit

{"title":"Using human language technologies in aviation weather applications","authors":"L. Butgereit","doi":"10.1109/AFRICON.2004.1406620","DOIUrl":"https://doi.org/10.1109/AFRICON.2004.1406620","url":null,"abstract":"Flying over Africa can often be exciting and dangerous. More airline accidents per takeoff occur in Africa than anywhere else in the world. The paper investigates the use of human language technologies (HLT) in assisting the aviation industry in Africa. The CSIR recently investigated one aspect of aviation in Africa: the availability of terminal aerodrome forecasts (TAFs) for unmanned aerodromes. Although the South African Weather Service does release TAFs for many unmanned aerodromes, because of the lack of facilities, pilots (especially pilots flying into the bush) cannot obtain these TAFs timeously. The CSIR has developed an application which automatically translates TAFs into one or more human languages. The prototype dispenses TAFs in English, Afrikaans, Setswana, and Zulu for nearly 30 aerodromes in southern Africa. Both audio and textual output is available via normal telephone land line, cell phone and SMS. The audio output is provided by limited domain voices created especially for the TAF vocabulary and includes the correct pronunciation for aerodromes in southern Africa. In addition, a special, non-aviation version of the output is generated for residents living in the vicinity of an aerodrome. The CSIR developed a specific plug-in for the application which translates the TAF into a weather report which can be understood and used by people who are not involved in aviation. All of the software was developed using open source tools and utilities in order to provide a low cost solution to the problem","PeriodicalId":224116,"journal":{"name":"2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590)","volume":"15 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125622249","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

CDMA performance for rural telecommunication access 农村电信接入CDMA性能

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406652

P. Rasello, T. Afullo

引用次数: 0

Using the oscillation test method to test for delay faults in embedded cores 采用振荡试验方法对嵌入式铁芯中的延时故障进行检测

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406859

H. Vermaak, H. Kerkhoff

引用次数: 2

A load shedding controller for management of residential loads during peak demand periods 一种用于高峰需求时期住宅负荷管理的减载控制器

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406780

P. Govender, A. Ramballee, S. Moodley

{"title":"A load shedding controller for management of residential loads during peak demand periods","authors":"P. Govender, A. Ramballee, S. Moodley","doi":"10.1109/AFRICON.2004.1406780","DOIUrl":"https://doi.org/10.1109/AFRICON.2004.1406780","url":null,"abstract":"South Africa is experiencing an unprecedented increase in electricity consumption. A direct consequence of this increased demand is the enormous load burden that has been imposed on the nation's national electricity grid, especially during peak demand periods. One solution to this problem would be the construction of additional power generating facilities, at a great cost to the economy and more importantly the environment. A more viable solution would be to shift loads off the electricity grid's peak consumption demand periods. To this end we will propose a controller that will reduce the residential load demand burden on the electricity supply grid, plus improve the load factor. The proposed controller allows the user to adjust the threshold setpoint at which the controller must operate. The controller performs the necessary load shedding operations when the setpoint is exceeded. The efficacy of the proposed controller was assessed by managing the load demands of residential consumers. A comparison was made between residential peak period consumption, under controlled and uncontrolled conditions. These comparisons were based on the following aspects: total consumption, maximum demand and load factor. The cost of consumption for each customer was calculated by using a flat rate tariff. The tests demonstrated the following: increases in consumer savings, a significant reduction in maximum demand on the electricity grid during peak consumption periods and improvements in load factor.","PeriodicalId":224116,"journal":{"name":"2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114392121","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: 5

Algebraic attacks on cipher systems 对密码系统的代数攻击

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406830

W. Penzhorn

引用次数: 2

On the use of high bit rate transceivers for low duty cycle wireless sensor networks 高比特率收发器在低占空比无线传感器网络中的应用

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406888

S. Mahlknecht, M. Bock

引用次数: 4

Software architecture for real-time sensor analysis and control of the friction stir welding process 搅拌摩擦焊接过程实时传感器分析与控制软件体系结构

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406716

G. Kruger, T. V. van Niekerk, C. Blignault, D. Hattingh

引用次数: 3

Drug dosage level design to maximize the benefits of therapy 药物剂量水平设计，使治疗效果最大化

2004 IEEE Africon. 7th Africon Conference in Africa (IEEE Cat. No.04CH37590) Pub Date : 2004-09-15 DOI: 10.1109/AFRICON.2004.1406718

A. M. Jeffrey, X. Xia, I. Craig

引用次数: 1