Abstract In this study, sodium cyanide leaching technology has been used to recover gold from tailings that are used by Mawelo small scale miners, located in Chunya district, Mbeya region, Tanzania. The sample collected was sent for analysis of mineralogical composition and average particle size. The fractions retained on each sieve, which ranged 180 – 500 μm were used in the leaching experiments. The leaching was implemented using sodium cyanide with concentration in the range of 500 – ...
ABSTRACT Magnetic induction (MI) is a physical layer technology that is effective for underground wireless communications. The underground communications involve three major communication links, namely underground to underground (UG2UG), underground to aboveground (UG2AG), and aboveground to underground (AG2UG). AG2UG and UG2AG links are special in a sense that they cross two different media, which are soil and free space. While this is the case, the soil electrical conductivity (EC) is prove...
ABSTRACT Teachers‟ Professional Development refers to a variety of activities both formal and informal, which is designed for a personal and professional growth for teachers. The advancement of technology has been recognized to play a valuable role in developing and improving the teaching and learning situations. This study, aims at analyzing the use of ICT in Teachers‟ professional among the Tanzanian Secondary School teachers. Data used in this study, were collected through a field data...
ABSTRACT Free Space Optics communications (FSO) has drawn a bunch of attention for a range of applications in telecommunications field. The unregulated bandwidth which is up to 200THz, security, higher speed, unlimited data rate, low deployment cost, and shortest installation time frame are the few reasons to employ FSO system. However, weather attenuation has a massive impact on the FSO transmission channel. In this study, the effect of scintillation on the performance and FSO link availabil...
ABSTRACT Non edible oil sources have the potential to lower the cost of biodiesel. However, they usually contain significant high amounts of free fatty acids (FFA) that make them inadequate for direct base catalyzed transesterification reaction (where the FFA content should be lower than 3%). The present work reviews chemical re-esterification as a possible method for the pre-treatment of high FFA feedstock for biodiesel production. The effects of temperature, amount of glycerol, type and amo...
Abstract Radio spectrum access is important for terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations. The services offered by terrestrial wireless networks, commercial earth observations and terrestrial radio astronomy observations have evolved due to technological advances. They are expected to meet increasing users’ demands which will require more spectrum. The increasing demand for high throughput by users necessitates allocating addit...
Abstract Problems associated with boilers are a major contributor to load losses in coal-fired power plants. The boiler furnace exit temperature is a key indicator of the combustion and heat transfer processes taking place and has a profound impact on the operation of the heat exchangers downstream of the furnace. Having a model that can predict the furnace exit temperature and heat flux distributions may enable furnace performance to be predicted without having to conduct extensive experimen...
ABSTRACT Clean modern energy and improved waste management are two well-recognised challenges in the global transition to sustainable development. There exist synergistic opportunities in simultaneously tackling the two issues via the generation of bioenergy from suitable waste streams. This potential has been successfully exploited elsewhere in the world; however, South Africa, despite having significant potential, lags behind in the implementation of these technologies and the respective ...
ABSTRACT In this thesis, a methodology for integrated catchment water resources assessment using Bayesian Networks was developed. A custom made software application that combines Bayesian Networks with GIS was used to facilitate data pre-processing and spatial modelling. Dynamic Bayesian Networks were implemented in the software for time-series modelling. The structures of three Bayesian Network models were created automatically using a Hybrid Genetic Algorithm (HGA) which was implemented in ...
ABSTRACT Dual Digestion is a two stage system that combines autotherm·a1 thermophilic aerobic pre-treatment with conventional anaerobic digestion. The practicability of the system using pure oxygen is well proven. Disadvantages are the high cost of the pure oxygen and the absence of a detailed evaluation of anaerobic digester performance. This report discusses the results of a full-scale investigation into the dual digestion system (184m3 aerobic reactor and 1800m3 anaerobic digester), carri...
BACKGROUND Integral to the biological nutrient removal (BNR) activated sludge system is the biologically mediated process of denitrification. Not only does this process reduce the N load to the environment, but it also has the advantages of alkalinity recovery and reducing the oxygen demand. Further, the denitrification protects the biological excess P removal (BEPR), if included, from the deleterious effect of recycling nitrate to the anaerobic reactor (Wentzel et al., 1990). Accordingly, qu...
ABSTRACT Terrorism, with explosions both in and outside buildings, has become a significant problem in the world. There are already several houses of unreinforced masonry, some of which are historical. But under blast loading they do not function well. Retrofitting methods have been developed to protect masonry buildings. Some research work has been carried out in recent years to study the impact of retrofitted URM walls; these experiments require usually significant time and funds. Also, wit...
ABSTRACT This thesis explores the development of a fixed wing unmanned aerial vehicle for delivery given the deplorable condition of roads leading to certain rural medical centers. This unmanned aerial vehicle has to be of the fixed wing type due to the weight to be carried and the distance which is to be covered. The thesis seeks to provide a greener alternative using a recyclable material i.e. strawboard for the body of the UAV, the UAV is also of a modular design hence it can easily be con...
Abstract Machining of Inconel 718 with whisker reinforced ceramic tool gave better performance in terms of tool life under high-pressure coolant supplies up to 15MPa compared to conventional coolant supplies. The use of 15MPa coolant supply pressure tend to suppress notching during machining thus improving tool life, while the use of higher coolant supply pressure of 20.3MPa did not show improvement in tool life due probably to accelerated notch wear caused by water jet impingement erosion. C...