The purpose of this paper is to compare the two most efficient lighting technologies available to... more The purpose of this paper is to compare the two most efficient lighting technologies available today for general and indoor applications. LED lighting with its unmatched energy efficacy and flexibility and fluorescent lighting with its affordability and matured technology will be tested in two case studies with the aid of a lighting simulation tool Relux, along with a feasibility study to form a conclusive comparison between fluorescent and LED lighting.
IET Conference on Renewable Power Generation (RPG 2011), 2011
In this paper, a dynamic model of solid-oxide fuel cell (SOFC) having a power rating of 30 kW has... more In this paper, a dynamic model of solid-oxide fuel cell (SOFC) having a power rating of 30 kW has been presented and implemented in PSCAD software. The SOFC system comprises a fuel cell (FC) stack and power conditioner, which comprises of a dc-dc boost converter and dc-ac inverter. The system also incorporates a Pi-controller to maintain output voltage of dc-dc boost converter at a desired level when there is a change in FC output voltage due to change in current supplied by it. Pulse width modulation (PWM) switching technique has been utilized for boost converter and inverter operation. The model has been tested for stand-alone and grid-connected operation and its load following performances. The model has also been tested under fault conditions on the grid-side. The simulation results obtained has been presented with analysis. (7 pages)
Only 40% of Zimbabwe’s population has access to electricity. The greater proportion of the power ... more Only 40% of Zimbabwe’s population has access to electricity. The greater proportion of the power is generated from thermal stations, with some from hydro and solar energy sources. However, there is little investment in the use of wind for electricity generation except for small installations in the Eastern Highlands, as Zimbabwe generally has wind speeds which are too low to be utilised for electricity generation. This paper presents the use of vertical wind profile extrapolation methods to determine the potential of generating electricity from wind at different hub heights in Zimbabwe, using the Hellman and exponential laws to estimate wind speeds. The estimated wind speeds are used to determine the potential of generating electricity from wind. Mangwe district in Matabeleland South province of Zimbabwe was used as a test site. Online weather datasets were used to estimate the wind speeds. The investigation shows that a 2.5kW wind turbine installation in Mangwe can generate more th...
The impact of electric loading such as current, copper loss and current density as well as the ef... more The impact of electric loading such as current, copper loss and current density as well as the effect of rotor speed on the performance of double stator (DS) permanent magnet (PM) machines are analyzed and presented in this work. MAXWELL-2D software package is used in predicting the results. The investigated machine variables include: phase flux-linkage, induced phase voltage, average torque, torque ripple, total harmonic distortion, losses and efficiency. The analysis shows that most of the machines’ output performances are principally dependent on both the operating speed and loading conditions; though, the average torque and phase flux-linkage is fairly insensitive to change in speed.
2013 IEEE 5th Conference on Engineering Education (ICEED), 2013
ABSTRACT Engineering Topics in Universities have expanded astronomically in recent years resultin... more ABSTRACT Engineering Topics in Universities have expanded astronomically in recent years resulting in congested curricula and concomitant pressure on students who opt to enroll in the various disciplines, which are also expanding. It is not a surprise therefore that Engineering Students spend more study hours than their colleagues in pursuing, for example, programmes in the social sciences. Under such pressures, many students fail to cope and overall pass rates are low. In this paper, the authors will present the results of a combination of interventions he has incorporated in his classes for study areas that include Engineering Design, Capstone Projects as well the delivery of individual course modules. Through a combination of the measures incorporated, the authors has observed a revived interest in engineering and improved performance. Among the techniques applied to more depth are, Creative Thinking, espoused in Edward de Bono's "Six Thinking Hats", Start Pugh's "Total Design" and a more in-depth implementation of a student's "Learning Portfolio". Through this combination of measures, the authors has achieved not only higher pass rates but also higher passing grades. More recently the authors devised an alternative to laboratory work in which students would as part of a group work on the construction a "Training Board" based on a industry type "script". In this manner, the students would not only have to face the challenge of engineering language, but would learn the dynamics of engineering, e.g. budgeting, purchasing, component sizing, project management and documentation.
2013 IEEE International Conference on Industrial Technology (ICIT), 2013
Ligthning phenomenon is a common occurrence in Southern Africa, particularly during the summer an... more Ligthning phenomenon is a common occurrence in Southern Africa, particularly during the summer and rainy season. Cloud-to-ground lightning is a common natural atmospheric hazard in Zimbabwe. Despite, Zimbabwe being one of the countries with high casualty figures expressed as annual deaths per million, the country currently has no installed Lightning Location and Detection (LLD) System. The Meteorological Services Department of Zimbabwe appears to be relying on word of mouth in compiling statistics on lightning activity and lightning-related casualties in Zimbabwe. This paper presents an online monitoring system that monitors the incidence and severity of lightning and sends the acquired data to an online central server using GSM network in real time. It discusses the design and implementation of an Intelligent Electronic Device (IED) for online monitoring of lightning incidence and severity in rural Zimbabwe using GSM network. The intelligent electronic device captures the signals it receives from a lightning detector before sending the data to a central server using GSM network.Initial laboratory tests were carried out and the device managed to successfully send SMS messages to a central server.
Psychotherapy research : journal of the Society for Psychotherapy Research, 2021
OBJECTIVE To provide evidence of the effectiveness of a brief relapse prevention intervention usi... more OBJECTIVE To provide evidence of the effectiveness of a brief relapse prevention intervention using implementation intentions (Self-Management after Therapy, SMArT), following remission from depression and to identify effective relapse prevention strategies. METHOD The SMArT intervention was provided to 107 patients who were recovered after psychological therapy for depression. Relapse events were calculated as reliable and clinically significant increases in PHQ-scores. Sixteen patients receiving the intervention and eight practitioners providing it were interviewed. Framework Analysis identified seven themes which highlighted effective relapse prevention strategies and effective implementation of the SMArT intervention. RESULTS Relapse rates at the final SMArT session (four months after the end of acute stage therapy) were 11%. Seven themes were identified that supported effective self-management: (1) Relationship with the practitioner-feeling supported; (2) Support networks; (3) ...
Advances in microprocessors and micro controller technologies have brought with them many opportu... more Advances in microprocessors and micro controller technologies have brought with them many opportunities. These opportunities are being exploited to great economic benefit in the developed world and to a lesser extend by developing countries. At the same time the nature of our industrial plants is changing and computer chips are encountered even in the most elementary equipment. However many educational institutions still approach the teaching of electrical power courses with little attention to these vital new realities with the result that graduates are technologically handicapped when they enter the world of work. This paper sets out to analyze the situation at the University of Zimbabwe and Cape Technikon, South Africa and proceeds to propose new solutions.
1 Edward Chikuni, University of Zimbabwe, Department Of Electrical Engineering, PO BOX MP 167, Mt... more 1 Edward Chikuni, University of Zimbabwe, Department Of Electrical Engineering, PO BOX MP 167, Mt Pleasant Harare, Zimbabwe. e-mail: chikuni@yahoo.com 2 Gibson Madungwe, University of Zimbabwe, Department Of Electrical Engineering, PO BOX MP 167, Mt Pleasant Harare, Zimbabwe. e-mail: Gibson.Madungwe@ieee.org Abstract  The problem of brain drain, involving migration of professionals from developing countries to developed countries is well documented. The situation does not seem to getting better and sooner rather than later both developed and developing countries have to come together to resolve this problem. The authors start the paper with general discussion of origins and destinations of highly trained engineering educators in developing countries with estimates of what it costs to train them. In their paper, the authors pose scenarios and options that they consider important including new opportunities resulting from high technology, globalisation and Internet. Among the scenari...
Permanent magnet (PM) synchronous machines having double-stator and equipped with non-overlapping... more Permanent magnet (PM) synchronous machines having double-stator and equipped with non-overlapping concentrated windings, is analyzed in this paper. Thus, there is reduced copper loss, resulting to improved efficiency. Basically, the analyzed machine is a doubly-salient stator-PM machine, with a rotor made of modulating steel ring. The analysis includes the open circuit and on-load characteristics of the developed machines. Furthermore, a quantitative comparison of the electromagnetic analysis of the machines having different winding topology is also detailed in this study. The investigation shows that the even-rotor pole machines are characterized by higher cogging torque as well larger torque ripple, relative to their odd-rotor pole counterparts, due to their high possession of harmonics.
The Spotlight Synthetic Aperture Radar (SSAR) is capable of producing high quality images with ve... more The Spotlight Synthetic Aperture Radar (SSAR) is capable of producing high quality images with very high resolution in both the azimuth and range when operated with long duration pulses. Long duration pulses also allow high power to be transmitted using miniaturized radar transmitters, thus also extending the radar range. The major drawback to the use of long duration radar pulses is the need for a large radar memory and the reduction in processing speed. Segmentation of the radar data and its parallel processing addresses the limitation of memory and processing speed. However, the recombination of processed segments reduces the image quality due to recombination errors. The use of both Fast Fourier transformation (FFT) and Discrete Cosine transformation (DCT) in SSAR data processing eradicates the errors associated with sub-image reconstruction.
The analysis of cogging torque, torque ripple and total harmonic distortion of a permanent magnet... more The analysis of cogging torque, torque ripple and total harmonic distortion of a permanent magnet (PM) flux-switching machine having separate excitation stators is presented in this study. Further, the effect of unbalanced magnetic force (UMF) on the rotor of this machine is also investigated. A comparison of the analysed machine having different rotor pole configurations is also given. The analysis shows that the largest cogging torque, torque ripple as well as total harmonic distortion (THD) are obtained in the four-rotor-pole machine while the least of THD and torque ripple effects is seen in the thirteen-rotor-pole machine. Furthermore, the evaluation of the radial magnetic force of the machines having an odd number of rotor poles shows that the investigated machine having a five-rotor-pole number exhibits the highest value of UMF, while the smallest amount of UMF is obtained in an eleven-rotor-pole machine. Similarly, it is observed that the machines having an even number of ro...
Recent policy discussions on energy use in Zimbabwe sparked interest in the economic case for ene... more Recent policy discussions on energy use in Zimbabwe sparked interest in the economic case for energy efficiency, suggesting the need to investigate the relevant costs and benefits. This paper investigated the potential of energy efficiency in manufacturing industries in Zimbabwe. Data collection was done using questionnaires, walk-through audits and semi-structured interviews. The data set was then analysed using regression analysis. The results show that there would be significant potential energy saving in Zimbabwe through adopting various energy efficiency programmes. The main energy efficiency barriers identified were: poorly structured electricity tariffs; risk of production disruption; resistance of operational staff to a changed working style; lack of coordination between company divisions; lack of information on energy efficiency programmes; and lack of support from senior management on issues that relate to energy efficiency. A straightforward energy efficiency policy frame...
The purpose of this paper is to compare the two most efficient lighting technologies available to... more The purpose of this paper is to compare the two most efficient lighting technologies available today for general and indoor applications. LED lighting with its unmatched energy efficacy and flexibility and fluorescent lighting with its affordability and matured technology will be tested in two case studies with the aid of a lighting simulation tool Relux, along with a feasibility study to form a conclusive comparison between fluorescent and LED lighting.
IET Conference on Renewable Power Generation (RPG 2011), 2011
In this paper, a dynamic model of solid-oxide fuel cell (SOFC) having a power rating of 30 kW has... more In this paper, a dynamic model of solid-oxide fuel cell (SOFC) having a power rating of 30 kW has been presented and implemented in PSCAD software. The SOFC system comprises a fuel cell (FC) stack and power conditioner, which comprises of a dc-dc boost converter and dc-ac inverter. The system also incorporates a Pi-controller to maintain output voltage of dc-dc boost converter at a desired level when there is a change in FC output voltage due to change in current supplied by it. Pulse width modulation (PWM) switching technique has been utilized for boost converter and inverter operation. The model has been tested for stand-alone and grid-connected operation and its load following performances. The model has also been tested under fault conditions on the grid-side. The simulation results obtained has been presented with analysis. (7 pages)
Only 40% of Zimbabwe’s population has access to electricity. The greater proportion of the power ... more Only 40% of Zimbabwe’s population has access to electricity. The greater proportion of the power is generated from thermal stations, with some from hydro and solar energy sources. However, there is little investment in the use of wind for electricity generation except for small installations in the Eastern Highlands, as Zimbabwe generally has wind speeds which are too low to be utilised for electricity generation. This paper presents the use of vertical wind profile extrapolation methods to determine the potential of generating electricity from wind at different hub heights in Zimbabwe, using the Hellman and exponential laws to estimate wind speeds. The estimated wind speeds are used to determine the potential of generating electricity from wind. Mangwe district in Matabeleland South province of Zimbabwe was used as a test site. Online weather datasets were used to estimate the wind speeds. The investigation shows that a 2.5kW wind turbine installation in Mangwe can generate more th...
The impact of electric loading such as current, copper loss and current density as well as the ef... more The impact of electric loading such as current, copper loss and current density as well as the effect of rotor speed on the performance of double stator (DS) permanent magnet (PM) machines are analyzed and presented in this work. MAXWELL-2D software package is used in predicting the results. The investigated machine variables include: phase flux-linkage, induced phase voltage, average torque, torque ripple, total harmonic distortion, losses and efficiency. The analysis shows that most of the machines’ output performances are principally dependent on both the operating speed and loading conditions; though, the average torque and phase flux-linkage is fairly insensitive to change in speed.
2013 IEEE 5th Conference on Engineering Education (ICEED), 2013
ABSTRACT Engineering Topics in Universities have expanded astronomically in recent years resultin... more ABSTRACT Engineering Topics in Universities have expanded astronomically in recent years resulting in congested curricula and concomitant pressure on students who opt to enroll in the various disciplines, which are also expanding. It is not a surprise therefore that Engineering Students spend more study hours than their colleagues in pursuing, for example, programmes in the social sciences. Under such pressures, many students fail to cope and overall pass rates are low. In this paper, the authors will present the results of a combination of interventions he has incorporated in his classes for study areas that include Engineering Design, Capstone Projects as well the delivery of individual course modules. Through a combination of the measures incorporated, the authors has observed a revived interest in engineering and improved performance. Among the techniques applied to more depth are, Creative Thinking, espoused in Edward de Bono's "Six Thinking Hats", Start Pugh's "Total Design" and a more in-depth implementation of a student's "Learning Portfolio". Through this combination of measures, the authors has achieved not only higher pass rates but also higher passing grades. More recently the authors devised an alternative to laboratory work in which students would as part of a group work on the construction a "Training Board" based on a industry type "script". In this manner, the students would not only have to face the challenge of engineering language, but would learn the dynamics of engineering, e.g. budgeting, purchasing, component sizing, project management and documentation.
2013 IEEE International Conference on Industrial Technology (ICIT), 2013
Ligthning phenomenon is a common occurrence in Southern Africa, particularly during the summer an... more Ligthning phenomenon is a common occurrence in Southern Africa, particularly during the summer and rainy season. Cloud-to-ground lightning is a common natural atmospheric hazard in Zimbabwe. Despite, Zimbabwe being one of the countries with high casualty figures expressed as annual deaths per million, the country currently has no installed Lightning Location and Detection (LLD) System. The Meteorological Services Department of Zimbabwe appears to be relying on word of mouth in compiling statistics on lightning activity and lightning-related casualties in Zimbabwe. This paper presents an online monitoring system that monitors the incidence and severity of lightning and sends the acquired data to an online central server using GSM network in real time. It discusses the design and implementation of an Intelligent Electronic Device (IED) for online monitoring of lightning incidence and severity in rural Zimbabwe using GSM network. The intelligent electronic device captures the signals it receives from a lightning detector before sending the data to a central server using GSM network.Initial laboratory tests were carried out and the device managed to successfully send SMS messages to a central server.
Psychotherapy research : journal of the Society for Psychotherapy Research, 2021
OBJECTIVE To provide evidence of the effectiveness of a brief relapse prevention intervention usi... more OBJECTIVE To provide evidence of the effectiveness of a brief relapse prevention intervention using implementation intentions (Self-Management after Therapy, SMArT), following remission from depression and to identify effective relapse prevention strategies. METHOD The SMArT intervention was provided to 107 patients who were recovered after psychological therapy for depression. Relapse events were calculated as reliable and clinically significant increases in PHQ-scores. Sixteen patients receiving the intervention and eight practitioners providing it were interviewed. Framework Analysis identified seven themes which highlighted effective relapse prevention strategies and effective implementation of the SMArT intervention. RESULTS Relapse rates at the final SMArT session (four months after the end of acute stage therapy) were 11%. Seven themes were identified that supported effective self-management: (1) Relationship with the practitioner-feeling supported; (2) Support networks; (3) ...
Advances in microprocessors and micro controller technologies have brought with them many opportu... more Advances in microprocessors and micro controller technologies have brought with them many opportunities. These opportunities are being exploited to great economic benefit in the developed world and to a lesser extend by developing countries. At the same time the nature of our industrial plants is changing and computer chips are encountered even in the most elementary equipment. However many educational institutions still approach the teaching of electrical power courses with little attention to these vital new realities with the result that graduates are technologically handicapped when they enter the world of work. This paper sets out to analyze the situation at the University of Zimbabwe and Cape Technikon, South Africa and proceeds to propose new solutions.
1 Edward Chikuni, University of Zimbabwe, Department Of Electrical Engineering, PO BOX MP 167, Mt... more 1 Edward Chikuni, University of Zimbabwe, Department Of Electrical Engineering, PO BOX MP 167, Mt Pleasant Harare, Zimbabwe. e-mail: chikuni@yahoo.com 2 Gibson Madungwe, University of Zimbabwe, Department Of Electrical Engineering, PO BOX MP 167, Mt Pleasant Harare, Zimbabwe. e-mail: Gibson.Madungwe@ieee.org Abstract  The problem of brain drain, involving migration of professionals from developing countries to developed countries is well documented. The situation does not seem to getting better and sooner rather than later both developed and developing countries have to come together to resolve this problem. The authors start the paper with general discussion of origins and destinations of highly trained engineering educators in developing countries with estimates of what it costs to train them. In their paper, the authors pose scenarios and options that they consider important including new opportunities resulting from high technology, globalisation and Internet. Among the scenari...
Permanent magnet (PM) synchronous machines having double-stator and equipped with non-overlapping... more Permanent magnet (PM) synchronous machines having double-stator and equipped with non-overlapping concentrated windings, is analyzed in this paper. Thus, there is reduced copper loss, resulting to improved efficiency. Basically, the analyzed machine is a doubly-salient stator-PM machine, with a rotor made of modulating steel ring. The analysis includes the open circuit and on-load characteristics of the developed machines. Furthermore, a quantitative comparison of the electromagnetic analysis of the machines having different winding topology is also detailed in this study. The investigation shows that the even-rotor pole machines are characterized by higher cogging torque as well larger torque ripple, relative to their odd-rotor pole counterparts, due to their high possession of harmonics.
The Spotlight Synthetic Aperture Radar (SSAR) is capable of producing high quality images with ve... more The Spotlight Synthetic Aperture Radar (SSAR) is capable of producing high quality images with very high resolution in both the azimuth and range when operated with long duration pulses. Long duration pulses also allow high power to be transmitted using miniaturized radar transmitters, thus also extending the radar range. The major drawback to the use of long duration radar pulses is the need for a large radar memory and the reduction in processing speed. Segmentation of the radar data and its parallel processing addresses the limitation of memory and processing speed. However, the recombination of processed segments reduces the image quality due to recombination errors. The use of both Fast Fourier transformation (FFT) and Discrete Cosine transformation (DCT) in SSAR data processing eradicates the errors associated with sub-image reconstruction.
The analysis of cogging torque, torque ripple and total harmonic distortion of a permanent magnet... more The analysis of cogging torque, torque ripple and total harmonic distortion of a permanent magnet (PM) flux-switching machine having separate excitation stators is presented in this study. Further, the effect of unbalanced magnetic force (UMF) on the rotor of this machine is also investigated. A comparison of the analysed machine having different rotor pole configurations is also given. The analysis shows that the largest cogging torque, torque ripple as well as total harmonic distortion (THD) are obtained in the four-rotor-pole machine while the least of THD and torque ripple effects is seen in the thirteen-rotor-pole machine. Furthermore, the evaluation of the radial magnetic force of the machines having an odd number of rotor poles shows that the investigated machine having a five-rotor-pole number exhibits the highest value of UMF, while the smallest amount of UMF is obtained in an eleven-rotor-pole machine. Similarly, it is observed that the machines having an even number of ro...
Recent policy discussions on energy use in Zimbabwe sparked interest in the economic case for ene... more Recent policy discussions on energy use in Zimbabwe sparked interest in the economic case for energy efficiency, suggesting the need to investigate the relevant costs and benefits. This paper investigated the potential of energy efficiency in manufacturing industries in Zimbabwe. Data collection was done using questionnaires, walk-through audits and semi-structured interviews. The data set was then analysed using regression analysis. The results show that there would be significant potential energy saving in Zimbabwe through adopting various energy efficiency programmes. The main energy efficiency barriers identified were: poorly structured electricity tariffs; risk of production disruption; resistance of operational staff to a changed working style; lack of coordination between company divisions; lack of information on energy efficiency programmes; and lack of support from senior management on issues that relate to energy efficiency. A straightforward energy efficiency policy frame...
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