A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. October 2017 / Increasing concerns over environmental and geo-political issues on resources’ sustainability have driven the industries to shift their efforts to produce chemicals from renewable biomass. Amongst the lignocellulosic biomass, corncob contains cellulose, hemicellulose and lignin that are built in a compact structure which makes it difficult to access. Pre-treatment is then applied to make the content to be accessible to enzymatic hydrolysis which breaks down the polysaccharides to monomers. The sugar monomers can be converted to a wide range of bioproducts such as biofuels and bio-chemicals. The objective of the study was to determine, evaluate and optimize the best solvent system to pre-treat corn cob. In addition, the study evaluated the effect of pre-treatment parameters on the yield of cellulose and hemicellulose and attempt to develop a kinetic model to explain the dissolution. Lithium perchlorate, zinc chloride, phosphoric acid, sulphuric acid and sodium hydroxide were used during the pre-treatment, which was carried out at 70-80 ° C for 6 hours. Characterization of pre-treated samples showed a significant change in structure after pretreatment indicating disruption in cell wall of the lignocellulosic material. FTIR revealed a reduction in phenolic group; indicating that the lignin content has been reduced. The XRD patterns show that crystallinity was considerably reduced; this was shown by an increase in calculated crystallinity index (CrI) after LiClO4, ZnCl2, H3PO4 and NaOH pre-treatment. The CrI of raw corncob (CrI= 32.7%) increased to 46.2 %, 42.3 %, 55.6 % and 53.4 % of LiClO4, ZnCl2, H3PO4 and NaOH, respectively. The crystallinity index increased for pre-treated material, indicating that the amorphous cellulose is dissolved in the liquor, as well as lignin and hemicellulose removal This study has shown that LiClO4.2H2O pretreatment agent is an efficient solvent system to pretreat corncob which consecutively increase the accessibility of cellulose and hemicellulose from the solid fractions. The accessibility was confirmed by an ease hydrolysis of cellulose & hemicellulose to glucose & xylose respectively. An increase of nearly four times compared to the untreated corncob. The effect of reaction operating parameters i.e. Reaction time, temperature and solvent concentration was carried out and then optimized by response surface methodology (RSM) using Minitab 16. The target was to maximize the yield of cellulose and hemicellulose. It was discovered that the increase in temperature and reaction time increase the accessibility of cellulose and hemicellulose until an equilibrium is reached at 3 & half hours and 176 °c. The pretreatment solvent concentration was discovered to have an effect on the accessibility but not as much as temperature and time. The best pretreatment conditions to obtain high polysaccharides conversions to monomers were at 176°c for 3.5 hours using LiClO4.2H2O for 10 g of corncob. The results obtained from RSM were used to evaluate the temperatures profile, kinetic model for the corncob pretreatment as a function of temperature. The kinetics of pretreatment were studied by the amount of glucose, xylose and the lignin removed from the pretreated solids. The kinetic model of lignin removal and sugars accessibility was identified as a first-order reaction corresponding to the bulk phase for pretreatment time up to 24 hours. The rate constant results show that the kinetic rate increased with temperature. The activation energy for glucose, xylose and lignin were calculated to be 15.0 kJ/mol, 14.2 kJ/mol and 36.54 kJ/mol, respectively. / MT 2018

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 153-157).

Discharge hydrographs computed from the theory of linear flow through topologically random channel networks are compared to observed hydrographs on nine arid-region watersheds, with drainage areas ranging from 0.33 hectares to 1363 hectares, at the Walnut Gulch Experimental Watershed in southeast Arizona. Over 90 rainfall-runoff events are tested, with extremes ranging from 12.5 mm to 71 5 mm for rainfall depth, 0.4 mm to 50 mm for runoff volume, and 0.031 ems to 73.5 ems for peak discharge. Topologic Instantaneous Unit Hydrographs (TIUH's) are estimated from topologic and link-length parameters, and a scaling parameter. The topologic information is parameterized as the number of first-order links (magnitude) and the link-length distribution is parameterized by the mean. Both can be measured in the field or from topographic mapping and aerial photography. The scaling parameter is the "effective" kinematic celerity, which is a single-valued estimate of the kinematic celerity of the flow through the channel network for the duration of the event. The TIUH's lead to unit hydrographs, which are convolved with temporally distributed rainfall excess patterns computed using both the 0 index and the curve number, to give composite watershed hydrographs. Effective kinematic celerities are varied until the composite hydrographs match the observed hydrographs in terms of peak discharge and hydrograph efficiency. Results indicate that the TIUH approximately reproduces observed hydrographs, with calibrated effective kinematic celerities that fall within a reasonable range of magnitudes. Agreement between simulated and observed hydrographs is improved by introducing a lag to account for overland travel times to the channel network. The magnitude of the calibrated effective kinematic celerity is significantly related to watershed characteristics, including area, length, and slope. Regression equations are developed and the resulting predicted celerities are combined with map measured topologic and link-length parameters to give simulated hydrographs that approximately match the observed. Magnitude and link-length combine into a single parameter that is consistent across map scales and has the potential to be a watershed descriptor. Calibrated values of effective kinematic celerity vary little across map scales, suggesting that adequate results are obtained without additional expense for highly detailed mapping.

Thesis (Ph.D.)--Murdoch University, 2004. / Thesis submitted to the Division of Arts. Bibliography: p. 366-426.

Thesis (Ph. D.)--Carleton University, 1999. / Also available in electronic fromat on the Internet. Also available in electronic format on the Internet.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science in Engineering. March 2019 / Depleting fossil fuels and the increasing energy demand has necessitated the move to alternative renewable forms of energy. Lignocellulosic biomass is a renewable and sustainable source for highly valuable bio-based chemicals and material production in a biorefinery system. The effective fractionation of the main components of lignocellulosic biomass (cellulose, hemicellulose and lignin) into usable forms is a crucial step in unlocking an economically viable, high-value product producing biorefinery. The main concern associated with the conversion of lignocellulose is overcoming biomass recalcitrance using pretreatment while still maintaining a green, cost-effective and energy efficient process. Over the last decade, molten hydrate salts have been used for isolated cellulose dissolution, however very few studies have been done to check their ability in lignocellulosic biomass pretreatment. The aim of the study was to compare seven molten hydrate salt solvent systems including unary, binary and ternary mixtures of ZnCl2.4H2O, LiClO4.3H2O and Urea for the effective pretreatment of corncob in terms of physicochemical properties and pretreatment efficiencies and to optimise these efficiencies. The molten salt hydrate pretreatment systems used in this study are aimed at fractionating the corn cobs biomass into a solid fraction which mostly contains cellulose and lignin as the major components, while the liquid fraction contains hemicellulose as the main component. The pretreatment experiments were carried out at 70 for 60 minutes at a biomass: solvent ratio of 1:10. Physicochemical change after pretreatment was checked by FTIR, XRD and SEM. The most efficient solvent mixture was identified by gravimetric analysis for its ability to fractionate the biomass into a cellulose and lignin rich solid fraction and a hemicelluloserich liquid fraction. The effect of solvent pretreatment operating variables (temperature, time and solvent concentration) was investigated to maximize cellulose recovery, hemicellulose recovery in the liquid fraction and lignin recovery from the biomass by response surface methodology (RSM) approach using a central composite design (CCD). Physicochemical analysis showed a decrease in crystallinity and an increase in surface area after the pretreatment in all the MHS solvents tested. This work has successfully shown the use of ZnCl2.4H2O/ Urea, to pre-treat and fractionate corn cob with high recovery of cellulose (100%), low recovery of hemicellulose (42%) and lignin (44%) when compared to the other proposed systems. Through the RSM approach, optimum pretreatment conditions obtained Abstract were: 90 min, 120 oC and concentration of 71.32%/28.68 (w/w) ZnCl2.4H2O/ Urea. At these conditions, the predicted recovery for cellulose, hemicellulose and lignin 99.03%, 27.18% and 72.43% respectively with a desirability of 0.902. The actual recovery was 91%, 29% and 68% for cellulose, hemicellulose and lignin respectively at the same conditions. For a better understanding of the dissolution kinetics and thermodynamics of cellulose, hemicellulose and lignin dissolution in ZnCl2.4H2O/ Urea solvent system, a kinetic study was carried out. The results reveal the dissolution to be a 1st order kinetics and the obtained activation energy for cellulose, hemicellulose and lignin dissolution were 14.10 kJ.mol-1, 11.29 kJ.mol-1 and 7.606 kJ.mol-1 ,respectively. that the dissolution process for all three components are endothermic and endergonic. The -0.190; -0.195 kJ.mol-1) showed that the process of dissolution of hemicellulose occurred more rapidly and produced more stable products. It was concluded that ZnCl2.4H2O/ Urea pretreatment provided a potential way to fractionate lignocellulosic biomass which can improve the effective utilization of all feedstock fractions. / E.K. 2020

Lignin is an important component of biomass accounting for up to 30% by weight but up to 40% of the total energy content of the plant. As the push towards alternative fuels develops, more and more amounts of lignin will be gathered and used predominately as low grade boiler fuel to run primary processes. We argue there is usefulness in the conversion of lignin into value added specialty chemicals and fuels. In this work, a new approach for hydrodeoxygenation of lignin model compounds using platinum as the catalyst and organic solvent as the reaction medium was conducted, and the results were compared with those obtained using water as the reaction medium. It is shown that the organic solvent, with its increased hydrogen solubility, is able to hydrogenate the model compound with the same effect at lower temperature, hydrogen pressure, and time.

This paper presents the role of alternative energy technologies in displacing fossil fuels as the world's primary energy source. To that end, a CAPM-GARCH multi-factor market model is used to investigate the relationship between returns on oil and alternative energy stocks. Results show that an increase in oil prices and the broad market have a statistically significant and positive impact on alternative energy stock returns. Furthermore, the alternative energy sector is substantially more risky than the broad market but has the potential for higher returns. This highlights the infancy and inherently risky nature of the alternative energy sector today, but demonstrates the potential for substantial future investment gain as alternative energy technologies become more mature and widely available. Interestingly, estimation of the alternative energy index model indicated the presence of abnormal returns which was not the case for the solar index model, implying that the abnormal returns were generated from a different sectoral component of the alternative energy index.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology. / Distributed Generation systems based on renewable energy sources, such as wind or solar are mostly intermittent sources, due to their dependency on the weather, whereas those based on other primary energy sources are non-intermittent. All of them are specially designed to be integrated into distribution systems, in order to improve the power demand of consumers. In the last few decades of the twentieth century, several different factors have played a key role in increasing interest in systems. Distributed Generation (DG) is gaining more and more attention worldwide as an alternative to large-scale central generating stations. The aim of this research project is to investigate the contribution of distributed generation in fault current level in a power distribution system. The simulation results indicate that DG can have a positive or negative impact, on the fault current level in distribution network systems. The DG location and size affect the fault level. The second aim of this research was to suggest a model-based method for design, and implementation of a protection scheme for power distribution systems, by establish algorithms in a hardware environment. The overcurrent relay was chosen for the model development because it is considered a simple and popular protection scheme, and it is a common scheme in relaying applications. The proposed relay model was tested for fault conditions applied on a simple power system in different scenarios. The overcurrent relay model was implemented in MATLAB/Simulink, by using MATLAB programming languages and the SimPowerSystem (SPS) Tool. MATLAB/SIMULINK software is applicable to the modelling of generation, transmission, distribution and industrial grids, and the analysis of the interactions of these grids. This software provides a library of standard electrical components or models such as transformers, machines, and transmission lines. Therefore, the modelling and simulations are executed using MATLAB/Simulink version 2014b

This dissertation deals with the economic aspect of culture and focuses on the patterns of renewable natural resources utilisation among the people living in the Matutuine District of Southern Mozambique. The study also focuses on the demography, history and socio-political organisation of the area. Against this background the study emphasises the importance of the fact that these aspects will have to be taken into account if the establishment of the planned Lubombo Transfrontier Conservation Area in the same region is to be in any way successful. This area has no conservation status at present but has been earmarked to become part of the Lumbobo Transfrontier Conservation Area. This will mean that the entire area, or a substantial part thereof, will have to be proclaimed as a protected area. In Southern Africa the establishment of conservation areas have often been coupled with the removal of people from such areas. People removed from land declared as nature conservation areas were often denied access to resources they previously utilised to survive. The research findings indicate that the local people who live in the Matutuine District of Mozambique are extremely dependent on the natural environment for their everyday survival. The vast majority of people are concentrated in small villages where they practise subsistence agriculture. Due to nutrient poor soils and other factors, the local people are not able to produce enough foodstuffs to fulfil their survival needs. Although most people own small stock, the absolute minority of people own cattle. This is largely, although not solely attributable to the turbulent history of the area, especially the effects of the Mozambican Civil War. The poverty of the people in the area increases their dependence on natural resources. Local people supplement their diets by fish, caught in the lakes and rivers in the area, and wild fruits. Due to the effects of the Civil War, most fauna in the area have been depleted but people still hunt wild animals, especially small game, for food. The local people are thus extremely dependent on the resource base of the area earmarked to become part of the Lubombo Transfrontier Conservation Area. With the information presented in this study it is possible for the planners of the Lubombo Transfrontier Conservation Area to devise a strategy that will not impair the livelihoods of the local people who live in the area, but instead accommodate their socio-economic needs in the planning process and in the eventual establishment of the Lubobo Transfrontier Conservation Area. / Dissertation (MA (Anthropology))--University of Pretoria, 2006. / Anthropology and Archaeology / Unrestricted