Browsing by Author "Kasembe, Ethel Donald"

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    Factors for successful diffusion of information and communication technologies (ICTs) in Tanzanian small and medium enterprises (SMEs)
    (University of Dar es Salaam, 2004) Kasembe, Ethel Donald
    The world is undergoing a rapid change towards knowledge-based economic structures through development use and achievements realized through Information and Communication Technologies (ICTs) applications. ICTs in developing countries are under-utilized due to various reasons including lack of expertise, system-level factors, such as the lack of standardization, regulatory impediments, weaknesses in financial mechanisms, poorly organized inter-firm relationships and cultural influences. To assist Tanzanian Small and Medium Enterprises (SMEs) with access to ICTs, it is imperative that factors for successful diffusion of ICTs are established. Such a study will help organizations create positive influence of diffusion of ICTs and hence successful applications. Also the study helps SMEs to understand the importance of ICTs in such organizations and businesses. The outcomes of such studies are likely to enhance ICTs utilization and consequently enjoy its benefits. A number of factors for successful technology investment from the TIPS method which fall into six areas have been borrowed in assessing and evaluating ICTs diffusion. Identified areas include communications, financial, external influence, human factors, corporative characteristics and technology attributes. An approach which is thought to be a backbone of any technological diffusion and dissemination.
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    Modeling thermodynamics of high temperature gasification process of biomass
    (University of Dar es Salaam, 2013) Kasembe, Ethel Donald
    The motive of this research endeavour was to model biomass thermal-chemical gasification process to identify inefficiencies in the high temperature environment. A downdraft gasifier was the focal research area since it is the least efficient unit in the gasification chain of components with losses of about 55% and require re-dress by use of mathematical modeling. The model evokes the first law of thermodynamics (quantification of energy) and the second laws of thermodynamics (qualification energy processes) to account for exergy. Gasification temperature was varied from 800 K to 1400 K at equivalence ratios (ER) from 0.3 to 0.4. The model results of syngas heating values, syngas composition, cold and second law thermodynamic efficiencies for five biomass materials; palm stem, rice husks, sugar bagasse, jatropha cake and jatropha husks in a downdraft gasifier are reported. Predictions from the current model show a reasonable degree of accuracy with those from gasification experiments and other models. The maximum cold efficiency values depended on the biomass materials and occurred at a temperature of 1400 K and ER of 0.3, and efficiencies varied from 64.6% to 81.6%. The corresponding maximum second law thermodynamic efficiency based on chemical and physical exergy at a temperature 1400K and ER of 0.4 varied from 70.9% to 79.9% while the efficiency which depends on chemical exergy ranged from 76.5% to 86.6%. In all these cases the degree of irreversibility (exergy losses) was less than 30%. Use of high temperature gasification process is recommended due to the enhancement of gasification efficiency when compared with low temperature gasification process. In this way, biomass resources can be used in a sustainable way in energy generation in place of fossil fuel resources, thus mitigating environmental degradation.