Browsing Research articles (Dept of Electrical Engineering) by Title
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Now showing items 6-17 of 17
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Batane, N.R.; Morrison, D.J.; Moosbrugger, J.C. (Elsevier http://www.linkinghub.elsevier.com/retrieve/pii/S135964620800064X, NaN, 2008)[more][less]
Abstract: Results are presented on the effects of biaxial straining on the cyclic stress–strain response of ultrafine grain nickel (grain size 260 nm) and conventional grain nickel (grain size 50 lm) over a range of effective plastic strain amplitudes from 1 10 4 to 1 10 3. Grain refinement causes an increase in saturation stress. For conventional grain nickel, non-proportional straining causes higher saturation stress than proportional straining; but the ultrafine grain material exhibits the opposite behavior. URI: http://hdl.handle.net/10311/662 Files in this item: 1
Batane_SM_2008.pdf (586.5Kb) -
Yanev, K.M.; Obok Opok, A.; Litchev, A. (University of Botswana, www.ub.bw, NaN, 2004)[more][less]
Abstract: Maintenance of the proper power factor is a very important matter for the industry and for the economy of any country. A study of the power factor value for a number of industrial plants in Botswana shows that they operate at power factors lower that the optimal values. If a plant power factor is different from its optimal value, this will cause considerable loses in terms of investments for large power generation and supply equipment and in terms of heat dissipation from the supply lines and other equipment. To improve the power factor and keep it at an optimal value, there are a number of preventative measures, as well as corrective actions that could be implemented. The power factor of a plant changes, depending on the number of electrical units operating at a time. After a full analysis of the power factor issue and its optimal case, are automatic control is designed that may maintain the power factor of a plant within values close to optimal. Similar automatic power factor control system can be introduced for all industrial plants with unsatisfactory power factor throughout the country that can improve considerably the efficiency of power utilization. URI: http://hdl.handle.net/10311/1062 Files in this item: 1
Yanev_BJT_2004.pdf (1.049Mb) -
Anderson, G.O. (IEEE http://www.saiee.org.za/publications/2008/sept/99-3-4.pdf, NaN, 2008)[more][less]
Abstract: The paper gives detailed analyses to help determine the increase in production costs due to the transmission of reactive power. On the basis of that and with due consideration to the cost of VARS compensation equipment, a mathematical model is developed to determine an economically justified transmission distance for VARS in electric power systems. Standard voltages and line parameters are used for the computations. MATLAB computer programming is used to obtain the numerical results. The developed mathematical model and the numerical results could be useful to electric power systems engineers. URI: http://hdl.handle.net/10311/414 Files in this item: 1
Anderson_SAIEE_2008.pdf (425.7Kb) -
Anderson, G.O.; Mokgwathi, T.S. (University of Botswana, NaN, 2000)[more][less]
Abstract: Engineering and training play an important role in the technical, economic and social progress of society.A number of factors influence the education and training of engineers, from the nature and form of curricular to needs of employers and the changing patterns of professional employment. Key issues are being raised by changes in technology, in society and by the impact of developments in information technology on industry and commercial development, on the engineer profession, on the educational institutions and on education and training of engineers. The paper considers the education and training of engineers using data and information from the Faculty of Engineering and Technology(FET), University of Botswana as a case study. Historical background is introduced.Student enrolment in terms of gender and foreign students are presented.Also presented are the academic programs and staff structures.The goals of the Faculty have been highlighted and strategies to be applied to achieve these goals have been recommended. The paper could be of interest to staff of FET and UB, Engineering Institutions in Africa and also to the Botswana Ministry of Finance and Manpower Development. URI: http://hdl.handle.net/10311/674 Files in this item: 1
Anderson_BJT_2000.pdf (1.982Mb) -
Daka, J.S.J. (University of Botswana, NaN, 1998)[more][less]
Abstract: There are many instances where a telephone call charge needs to be avaialable immediately after a call is made. Usually, for a fee a telecommunication provider can provide call charge for a particular call. Call charging systems provide this information automatically without recourse to a telecommunications service provider. The application of call charging systems include private automatic branch exchange line cards, home telephone bill monitoring, monitoring telephones in a telephone cafe booth or payphones. This paper examines the design of hardware and software of the sub-systems for a subscriber based call charging system. URI: http://hdl.handle.net/10311/616 Files in this item: 1
Daka_BJT_1998.pdf (1.141Mb) -
Mbewe, D.D. (University of Botswana, NaN, 1998)[more][less]
Abstract: This paper describes the fundamental principles of production and accomplishment of High Definition Television (HDTV)-the television system of the future.It looks at the parameters of high definition television (HDTV),and shows how the values of these parameters can be derived from consideration of the performance of the viewer's visual system. Bandwidth requirements for various TV and HDTV systems are compared, and a number of optical fibre transmission techniques are considered for HDTV. In conclusion it is stated that the large bandwidths demands of uncompressed HDTV can be met by emerging technology in optical fibre transmission systems-in particular, wavelength division multiplexing (WDM). The paper is as a result of a project study conducted by the author and a colleage when he studied for his degree at Essex University,England. It makes no reference to the development and relevance of HDTV in the African context. URI: http://hdl.handle.net/10311/627 Files in this item: 1
Mbewe_bjt_1998.pdf (1.386Mb) -
Litchev, A.I.; Yanev, K.M. (University of Botswana, NaN, 2006)[more][less]
Abstract: Analysis of the induction motor failures show, that a significant number of motors are damaged due to single phasing.At such conditions the current increases rapidly and the motor is subjected to burnouts and consequently to long downfalls in the corresponding industry.Normally all motors are protected against thermal overloading by bimetal relays, but they are not always capable to ensure protection at single phasing.A secure protection is needed to trip the motor off in any case of single phasing especially for high power motors. The problems related to the motor protection against single phasing are discussed in this paper paper and for ensuring of such protection an electronic circuit is proposed and described. The circuit reacts immediately whenever a motor line current gets zero.A signal from this circuit switches off the motor starter on failures of anyone of the three phases. In such way the motor burnouts and downfalls are prevented. URI: http://hdl.handle.net/10311/622 Files in this item: 1
Litchev_BJT_2006.pdf (1.753Mb) -
Uys, P.; Kiravu, C.; Mothibi, J. (Emerald http://www.emeraldinsight.com, NaN, 2004)[more][less]
Abstract: This paper reports on the process of developing a blended online engineering course at the Faculty of Engineering and Technology of the University of Botswana. It presents the actual development process in terms of its management, the University's preferred pedagogical approach to student-centred learning and the consequent technological choices and deployment. In that regard, the paper will demonstrate the development of the Electrical principles course (EEB211) focusing attention on what was done, how and what result was achieved. This paper will be a useful reference for all those staff expected to develop their online courses alongside their normal face-to-face lectures. URI: http://hdl.handle.net/10311/460 Files in this item: 1
Uys_CWIS_2004.pdf (702.2Kb) -
Litchev, A.I.; Yanev, K.M. (University of Botswana, NaN, 1999)[more][less]
Abstract: Electromagnets are essentials for the operation of relays, contactors and other electromagnetic apparatus and take part in driving control and protective circuits of industrial processes and power systems. Performance of each electromagnet affects the driving time and the stability of operation of such circuits. This paper examines the improvement of the performance of AC electromagnets by using two diodes. The theoritical analysis lead to expressions for calculating the maximum, average and minimum values of coil-currents. Due to the electromagnetic processes in the coil, the current becomes pulsating but unidirectional and better force-gap characteristics are achieved. Consideration are made for reduction of the mass ferromagnetic and copper materials in the electromagnets and for decreasing teh responding time. URI: http://hdl.handle.net/10311/683 Files in this item: 1
Litchev_BJT_1999.pdf (924.8Kb) -
Daka, J.S.J. (http://ijedict.dec.uwi.edu/viewarticle.php?id=555., NaN, 2008)[more][less]
Abstract: In August 2002, the University of Botswana changed from a yearlong to a semester based academic system. However, the progression regulations were not be fully implemented on the information system mainly due to problems of interpretation. Due to this, a manual system was used. The manual system could not cope in making recommendations for all students leading to some regulations not being applied. To address this, a revision of the regulations was undertaken in 2007. These regulations require implementation on the information system. This paper discusses the main aspects of the 2007 regulations and their implementation via a computer program. The paper shows that a complete implementation of the regulations is possible using a computer program. The program was applied to sample students' academic results to provide progression recommendations that were found to agree with expected results. The paper concludes that an information system based implementation ensures uniform application of regulations. URI: http://hdl.handle.net/10311/470 Files in this item: 1
DAka_IJEDICT_2008.pdf (154.8Kb) -
Shuma-Iwisi, M.V. (University of Botswana, NaN, 1998)[more][less]
Abstract: One of the application areas of digital multiplexers is in implementation of logic equations. Truth tables can be used as a design tool, but they become very limited when design details are explored.It will be shown in this paper that the Karnaugh map (K-map) is an essential tool in the systematic detailed design of combinational circuits using multiplexers. The K-map will be used in two ways.First as a visual tool and secondly as a tool for decision making criteria. URI: http://hdl.handle.net/10311/619 Files in this item: 1
Suma-Iwisi_BJT_1998.pdf (1.304Mb) -
Aghdasi, F.; Bhasin, A. (University of Botswana, NaN, 2004)[more][less]
Abstract: Asynchronous sequential circuits offer improved speed of operation when compared to their synchronous counterparts. However, the standard methods of asynchronous design require careful examination of the flow table for possible critical races and hazards. This complicates the design procedure and often leads to extra states and additional hardware. A number of new design methodologies which involve locally generating a clock and using it to self synchronize the machine have been proposed. Such clock signals are generated wherever an input changes, or by controlled excitation whenever a change of inputs necessitates a change of state. All such designs, where the circuit is timed by locally generated clocks, are called Self-Clocked Sequential Circuits. This paper uses a design methodology for the State variable toggling through data driven clocks to implement a Direct Memory Access Controller (DMAC) as a design example. The design is simulated on software and also implemented using discrete hardware components. The methodology can be extended to parallel controllers for neutral networks and automated using state assignment techniques already for synchronous parallel controllers. URI: http://hdl.handle.net/10311/648 Files in this item: 1
Aghdasi_BJT_2004.pdf (1.145Mb)
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Now showing items 6-17 of 17