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Nairobi, Kenya

Kimotho J.K.,JKUAT | Hwang P.,Yeungnam University
SAE Technical Papers | Year: 2011

Overreliance on petroleum products and environmental pollution from combustion emissions produced by automobiles has led to extensive research on hybrid electric vehicles, electric vehicles and their components. A key component in these vehicles is the electric motor, used for traction as well as powering other appliances like the compressor. Overheating in electrical motors results in detrimental effects such as degradation of the insulation materials, magnet demagnetization, increase in Joule losses and decreased motor efficiency and lifetime. Hence, it is important to find ways of optimizing performance and reliability of electric motors through effective cooling and consequently reduce operating and maintenance costs. This study describes 3D CFD simulations performed on a totally enclosed air over fan cooled brushless D.C. motor to identify the temperatures of the critical components of the motor. The energy sources are obtained from electromagnetic losses computed using MAXWELL, a commercial FEA software and bearing losses obtained through numerical methods developed by the authors. A finned casing is used as the heat sink and the effect of varying the fin geometry on the cooling performance is examined using three heat sink designs. The results show that the highest temperature occurs at the end windings and that this temperature can be reduced by up to 15% by introduction of a suitable finned housing. These results show that CFD can be effectively used to optimize the cooling performance of electric motors. Experimental tests are undergoing in order to validate the CFD results. Copyright © 2011 SAE International. Source


Siringi D.O.,JKUAT | Home P.,JKUAT | Chacha J.S.,University of Nairobi | Koehn E.,Lamar University
ARPN Journal of Engineering and Applied Sciences | Year: 2012

Although electro coagulation is an evolving technology that is being effectively applied today for wastewater treatment, the paucity of scientific understanding of the complex chemical and physical processes involved is limiting future design and hindering progress. The objective of this review through a survey of the literature is to bring the chemistry and physical processes involved into perspective and to focus attention on those areas critically needing research. © 2006-2012 Asian Research Publishing Network (ARPN). Source


Ndiritu H.M.,JKUAT | Oketch P.O.,JKUAT | Kihia J.W.,Kenya Power
Proceedings of the 27th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2014 | Year: 2014

Energy is a key driver of the economic progress and it is expected to play a significant role in Kenya's socio-economic development. The current amount of power generated in Kenya stands at 1,600 MW and this is insufficient to meet the industrial needs for the current population that is about 40 million people. There is urgent need to increase the amount of power to at least 15,000 MW for industrial goals to be met by the government as captured by Kenya, Vision 2030 economic blueprint. The main source of power in Kenya is hydroelectricity that contributes more than 50% of electricity. Thermal sources (petroleum) contribute about 30% while geothermal and other renewable sources contribute more than 10%. This distribution changes during drought season with thermal component increasing to more than 50%. It is notable that nonrenewable forms such as petroleum contribute a significant portion of power. This is in form of heavy fuel oil running internal combustion engines. There are a number of energy sources that are being sort to further increase amount of power in Kenya. These include use of waste biomass and waste heat to generate additional power from existing power plants. This paper explores the status of power production in Kenya with a focus on the level of utilization of waste biomass and waste heat for power generation. Source


Maobe M.A.G.,Jomo Kenyatta University of Agriculture and Technology | Gitu L.,Jomo Kenyatta University of Agriculture and Technology | Gatebe E.,Jomo Kenyatta University of Agriculture and Technology | Rotich H.,Kenya Bureau of Standards | And 4 more authors.
World Journal of Medical Sciences | Year: 2013

A diploid fungus, Candida albicans, is a form of yeast that is a casual agent of opportunistic oral and genital infections in humans and is traditionally treated using herbs. Amongst the indigenous herbs used for the purpose in Kisii region, southwest Kenya are: Carissa spinarum, Urtica dioica, Warburgia ugandensis, Senna didymobotrya, Physalis Peruviana, Bidens pilosa, Leonotis nepetifolia and Toddalia sciatica. A study was carried out on these herbal plants in the year 2011and 2012. The objective was to determine the antifungal activity of these herbs that are also used for the treatment of diabetes, malaria and pneumonia. In the study, leaf samples of these plants were obtained from Kisii region, washed, air-dried and milled. The samples were extracted with four solvents namely hexane, dichloromethane, ethyl acetate and ethanol. Portions of the crude extracts were screened against Candida albicans, by the well diffusion method. Results showed that the standard antibiotics namely chloramphenicol, minocycline, erythromycin and cotrimoazol had diameters of the inhibition zones measuring (mm), 33, 32, 31 and 25, respectively which indicated inhibition of microbial growth. However, the extracts of hexane and solvents had no antifungal activity against the Candida albicans as they had diameters of the inhibition zones of 12 mm. The dichloromethane extracts of Leonotis nepetifolia and Bidens pilosa showed antifungal activity of diameters of the inhibition zones measuring 19 mm and 16 mm respectively. The ethyl acetate extracts of Leonotis nepetifolia, Bidens Pilosa, Senna didymobotrya, Toddalia asiatica and Physalis Peruviana recorded antifungal activity with diameters of the inhibition zones measuring (mm) 24, 18, 18, 17 and 15 respectively. The ethanol extracts of Leonotis nepetifolia and Physalis Peruviana displayed antifungal activity with diameters of the inhibition zones 27 mm and 19 mm, respectively. The dichloromethane, ethyl acetate and ethanol extracts of Leonotis nepetifolia recorded maximum antifungal activity against Candida albicans. The findings suggest that the herbal extracts of Leonotis nepetifolia, Bidens Pilosa, Senna didymobotrya, Toddalia asiatica and Physalis Peruviana have a potential to control Candida albicans as they have diameter zone of inhibition above 12 mm. © IDOSI Publications, 2013. Source


Mwangi R.W.,JKUAT | Waweru R.,JKUAT | Mwathi C.W.,JKUAT
Journal of Theoretical and Applied Information Technology | Year: 2011

This research seeks to look into the design process that promotes the development of an educational computer game that supports teaching and learning processes. The research specifically looks at the design of an educational computer game for teaching and learning of the topic of functions. The topic is essential in the teaching and learning of Mathematics courses such as Discrete Mathematics, Real Analysis and Calculus among others at Jomo Kenyatta University of Agriculture and Technology (JKUAT) Kenya. The computer game was developed using the Basic Unified process (BUP) which is a streamlined version of the rational unified process (RUP). This is an Object Oriented methodology mostly used for small projects with few end users. Due to the few numbers of end users we used interview method of data collection to gather requirements for the computer game. A paper prototype was used to validate the requirements. Use cases were used for both analysis and design of the game while Class diagrams and activity diagrams were purely used for the design of the game. Owens' six top level design anatomy aided in the design of the computer game. The overall computer game design was based on Craw fords' computer game design sequence model. The well designed and developed game met all its user requirements and was able to facilitate the teaching and learning of Functions to Bachelor of Science in Mathematics and Computer Science students who were taking Discrete mathematics in their first year of study at JKUATs' Taita/Taveta campus. Development of heuristics for measuring interest, fun and motivation are recommendations given to aid in the evaluation of user satisfaction of educational computer games. © 2005-2011 JATI & LLS. All rights reserved. Source

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