Processing of Semi-Solid Gray Cast Iron Using the Cooling Plate Technique

A semi-solid processing technique combining a cooling plate and various mold materials is developed to produce high quality gray cast iron components. Flow behavior of semi-solid slurry along an inclined cooling plate is studied to establish the effect of plate orientation on the integrity of cast products. The concept of multiple-stage cooling is discussed by considering cooling rates at different stages of processing along the cooling plate and in sand, graphite and metallic molds to show the significance of cooling rate in determining component microstructure. The morphology of microstructure in cast components is discussed and image analysis results presented. A refined microstructure of primary austenite and graphite, and their characteristics associated with the use of different mold materials are reported. Angle of inclination of plate is shown to influence the morphology and quantity of precipitated phases. Finally, the effects of cooling plate and mold material on Vickers hardness and mechanical strength of cast components are discussed

A Study on Agricultural Residues as a Substitute to Fire Wood in Kenya: a Review on Major Crops

For Kenya, the use of fire wood is enormous that the exploitation of other energy resources such as biomass from agricultural residues is little known. Therefore, the main aim of this study is to investigate agricultural residues estimates for use as a substitute to fire wood and charcoal in Kenya. This solution is in line to the urgent needs of finding the alternative for the depleting fossil fuels. The study found that Kenya agricultural residue energy potential is about 187,000 TJ which enough to substitute fire wood in most regions if converted with suitable technologies. If all the available agricultural residues are used as substitution fuel for fire wood, Kenya could reinstate the 10% forest cover as recommended from the current 1.7%

Challenges of Implementing E-Learning in Kenya: A Case of Kenyan Public Universities

In this paper, we discuss the challenges experienced by Kenyan public universities in implementation of e-learning and recommend possible solutions towards its successful implementation. In the last few years, most Kenyan public universities have adopted e-learning as a new approach to teaching and learning. However, the implementation challenges faced by these universities have continued to impact negatively on its effective utilization. This paper presents the findings from a survey of 148 staff of three Kenyan public universities who are currently using e-learning in blended mode approach. The purpose of this study was to investigate the challenges hindering the implementation of e-learning in Kenyan public universities. Data was collected through questionnaires, in-depth interviews and document analysis. The findings reveal that e-learning comes with some challenges that must be addressed by Kenyan public universities before successful implementation can be realized. However, the benefits and opportunities presented by e-learning far outweigh the challenges. The paper finally recommends some possible solutions that public universities could embrace towards successful implementation of e-learning

Access to Electricity in Informal Settlements: Literature Review and Load Curve Estimation

Today, about one in four people in cities live in informal settlements with severe lack of basic needs such as modern, safe, and reliable energy services. This study analyses the topic of electricity access in informal settlements, apporting two main important contributions. Firstly, a systematic literature review regarding the electricity access in informal settlements is presented, followed by an integrative literature review, highlighting a gap in this study field. Secondly, a load curve estimation based on survey data from an informal settlement in Nairobi is presented. Results show a load curve with two peaks (260 kW around 9:30 and 210 kW around 21:45) and overall, an energy consumption of 2.8 MWh/day. To conclude, the research examines the extended energy deprivation suffered by the community, which results in an average increase of 143% in the electricity tariff