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The soil being delivered with sugar cane consignments. from the cane fields to the factories, has been a recent cause for concern in the South African sugar industry. The soil impurities increase the wear of processing machinery reduce extraction efficiency and represents an unnecessary transport of material. The cost due to soil was estimated at R63 million (about US $8 million) over the 1996/97-season. The need to reduce costs, due to the unwanted soil component, has been given a high priority. Ashing is currently used by the sugar industry to estimate the amount of soil in cane. Although simple to implement, the method is destructive, requires long processing times and limited to small sample sizes. In fecent times, non-destructive techniques have become more prominent in industry. Hence, the decision to apply such techniques to the soil in cane-problem. This dissertation describes an experimental investigation into Dual-Energy Transmission (DuET) and X-ray lmaging for quantifying the amount of soil in cane. DuET can determine the relative concentrations of the components of a binary mixture by measuring the transmission of low- and high-energy gamma photons through the mixture. The principle of DuET was successfully demonstrated with aqueous solutions of ferric chloride. Experimentally-determined mass attenuation coefficients of water and ferric chloride were compared to theoretical values. DuET was then applied to dried, shredded sugar cane spiked with various amounts of soil. Results showed large variations in the predicted soil concentrations. These variations were attributed to radiation scatter and incomplete volume sampling by the radioactive source. However, new experimental arrangements are expected to improve the technique: initial test results are given of a sample holder that continuously rotates a sample up and down through the source-detector axis. An alternative approach to processmg DuET-spectra, using the discrete wavelet transform coupled with an artificial neural network, is also introduced. X-ray Imaging was the second technique investigated. A literature survey revealed that this technique had not previously been applied to the soil in cane-problem. The present work constituted an initial investigation to determine the feasibility of applying X-ray imaging to measure the amount of soil in cane. The soil/cane-samples, that were used for DuET, were imaged us ing a commercial mammography unit, and the resulting radiographs were analysed using image processing techniques. Although the results are promising, a more comprehensive investigation is foreseen. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

The objective of this work was to determine the operating conditions which would maximise the crystallisation performance of continuous vacuum pans used in the sugar industry. The specific application investigated in detail is crystallisation of high grade product sugar (A-sugar) in a South African raw cane sugar factory. The optimisation studies are based on a detailed dynamic mathematical model of a continuous pan. Whilst this model is based on the published work of others, the selection of variables and the formulation of the equations have been structured to produce a modular model of an individual compartment with the minimum number of independent variables. The independent variables have also been selected to meet the requirements of both a state-space control formulation and those necessary for the dynamic programming technique of optimisation. The modular compartment models are linked together to model a multi-compartment pan and the steady state model is derived as a special case of the dynamic model. For the model to simulate the conditions in South African sugar factories adequately requires appropriate descriptions of sucrose solubility and growth kinetics. Given the limited applicability of published data, experiments were undertaken to determine these parameters. Sucrose solubility in impure solutions was determined in laboratory tests designed to approach equilibrium by dissolution at conditions approximating those during pan boiling. The dependence of crystal growth rate on the concentration of impurity present in the mother liquor was investigated in both laboratory scale and pilot scale batch pan boiling experiments. The primary dependence of crystal growth rate on the super-saturation driving force was determined by fitting the steady state model to results of tests on an industrial scale continuous pan. The dynamic programming technique was used in conjunction with the mathematical model to determine the operating conditions which maximise steady state crystallisation performance. Using the crystallisation parameters determined for South African conditions, this approach has shown that the conventional wisdom of running with high crystal contents in all compartments of continuous pans boiling A-massecuite is not optimum. Pans should operate at lower crystal contents in earlier compartments, only increasing to higher crystal contents towards the final compartment. The specific values depend on seed conditions, pan design and the solubility and growth kinetics. To reap the benefits of being able to determine the optimum steady state operating condition for a continuous pan, it is necessary to be able to achieve effective steady state operation under industrial conditions. This requires both a steady loading on the pan and effective control of the crystallisation conditions within the pan. To stabilise loading, a strategy has been developed which uses buffer tanks in an optimal way to damp out flow fluctuations. This strategy accommodates multiple buffer tanks in series without the amplification of disturbances that occurs with some of the simpler published techniques. The dynamic behaviour of absolute pressure control and compartment feed control were investigated in an industrial scale pan. This work has demonstrated the importance of high quality absolute pressure control and developed techniques for effective automatic tuning of pan feed controls. As part of this research, computer control systems were developed as tools to provide the appropriate monitoring and control of the experiments undertaken. / Thesis (Ph.D.)-University of Natal, 2002.

The main objective of this work is to propose a mechanism for the transfer of impurities into the sucrose crystal. To this end the transfer of impurities into the sucrose crystal was investigated, under crystallisation conditions similar to those found industrially. Most of the impurities, namely, colour bodies, potassium, calcium and starch, were selected on the basis of their industrial importance, but some exotic species, namely lithium and nickel, were chosen to represent other mono- and di-valent ions respectively, and dyes, such as methylene blue, which have been used in work with single crystal sucrose crystallisation, were included to make the results more general. A parameter to measure the rate at which impurities are transferred into the sucrose crystal was proposed. Experiments, carried out in a pilot plant evaporative crystalliser, were performed to establish the effect of selected factors on both the concentrations of impurities found in the sucrose crystal, and on the rate at which these impurities are incorporated into the crystal. All the factors selected, namely the rate of crystallisation, the temperature, the concentration and type of impurity, the diffusivity of the impurity in concentrated sucrose solutions, and the crystal dimensions, are shown to influence the rate of impurity transfer. Only the concentration in the feed and type of impurity, however, affect the final concentration of the impurity in the crystal. Concepts involving partition coefficients and adsorption isotherms were also investigated. The experimental data did not fit the adsorption isotherm models well, but the values obtained for the partition coefficients were similar to those quoted in the literature when exchange types of reactions are operative. Activation energies have been measured, both for the rate of crystallisation of sucrose, and for the rates of impurity transfer. The values obtained, particularly for the rate of impurity transfer, indicate that a transport mechanism is effective. The experimental results have been used to investigate the relevance of two models, one involving a two-step approach and the other an interfacial process, for the incorporation of the impurity into the sucrose crystal. The results obtained indicate that the interfacial breakdown model describes the transfer of all the impurities studied here, except for starch. / Thesis (Ph.D.)-University of Natal, Durban, 1998.

South Africa has an annual sugarcane milling capacity of about 22 million tonnes on average producing about 3.3 million tonnes of dry bagasse, of which one third is surplus to factory requirements. Currently surplus bagasse is used for furfural, pulp and paper and cogeneration but significant amounts still remain . This prompted the need to find viable alternative and appropriate technology to utilize the surplus. A laboratory pilot plant was used to investigate the production of activated carbon from bagasse. Experiments were carried out to investigate conditions for making the best activated carbon in a rotary batch kiln, and also to examine potential ene rgy recovery from process gases using Gas Chromatography. Derived results from the laboratory experiments were used to develop a conceptual design for a demonstration plant sited within a sugar mill. The conceptual design was evaluated for economic and environmental impacts using a robust Excel spreadsheet and GABI-3 modelling software respectively. Excellent activated carbon was produced from sugarcane bagasse by a two-stage physical process involving pyrolysis and gasification with steam. The best operating conditions were pyrolysis at 700°C for 1 hr and activation at 850°C for 1hr, a heating rate of 10°C/min and a steam flow of 15g/g of char per hour. The active carbon yield was 7% on dry bagasse basis with a Methylene Blue Number of 257mglg of carbon. The active carbon had a sugar decolourisation capacity of 20% at a carbon dosage rate of 0.7 wt% on Brix using clear juice (l2°Brix) and 70% at 0.5 wt% on Brix using brown liquor (65°Brix) . The Freundlich isotherm showed that the bagasse-based activated carbon was a suitable adsorbent for sugar colour bodies. Gas analysis results revealed that the off gases from the pyrolysis and activation stages had calorific values of about 63MJ and 31MJ per kg of activated carbon respectively . The total combustion energy of 94 MJ/kg of active carbon was enough to satisfy the process energy requirements for drying, pyrolysis and activation. By burning combustibles like tar, methane, carbon monoxide, ethylene and hydrogen for process thermal energy needs, the environmental impact of the manufacturing process was reduced to a Global Warming Potential of llkg CO2 Equiv per kg of carbon produced. The demonstration plant requires a capital investment of US$lOA million to give a competitive bagasse-based activated carbon (BPAC) selling price of US$1.80 per kg and IRR, ROI and Investment payback time of 17.93%, 23.93% and 3.80 years respectively. A sensitivity analysis was also carried out to investigate the effect of possible variation in the main project forecasts which are BPAe selling price , bagasse buying price, capital investment and production costs on IRR, ROI and payback time . The benefits of process integration within a sugar mill would be expected to improve the business feasibility ; If bagasse was free the IRR would increase to 28.59% and even better to 32.12% if extra boiler and electricity capacity was also available at the mill. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2005.

Magnesium Diboride (MgB₂) bulk superconductor has been manufactured for use in superconducting fault current limiters (SFCLs) via in situ reaction. SFCLs have proven to be a viable means for limiting surge currents on power lines by dissipating fault energy as the superconductor quenches. As the current limiting behaviour is determined by the normal resistance (Rn), research has been conducted to evaluate an effective means to increase Rn for bulk superconducting MgB₂. Other researchers have previously looked into the improvement and optimisation of the critical current, Jc, by carbon doping and other flux pinning techniques. Carbon doping has been confirmed as a means to increase Rn, and was implemented by chemical vapour deposition (CVD) at 600 ºC in a tubular furnace apparatus. Intragranular doping was achieved by CVD on the boron precursor powder. In situ manufacturing of MgB₂ bulk was performed using the reactive liquid magnesium infiltration technique. Carbon doping provided an adequate increase in Rn, for a small decrease in the critical temperature, Tc. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2012.

The use of multi angle laser light scattering on-line to size exclusion chromatography, analytical ultracentrifugation and viscosity measurements for the determination of molecular weights and conformations of polysaccharide systems is described. The use of several independent techniques for the characterization of polysaccharide systems was found to be essential due to the polydisperse nature of the materials. These techniques were used to investigate the changes in molecular size and conformation of guar gum due to irradiation. Molecular weights and viscosities were found to decrease significantly with increasing radiation dose. Conformational studies on the resulting series of homologous samples confirmed the random coil-like conformation of guar gum. Investigations on BSNdextran complexes, obtained by dry-heating at different molar ratios showed that complex formation (most likely by a Maillard-type reaction) only took place when a low molecular weight dextran fraction was used. The highest molecular weight complexes were obtained when the BSA ratio was high, suggesting that some form of association between individual complexes and/or BSA had taken place.

The motor industry is one of the leading industries in the South African economy. The MIDP, an import/export complementary arrangement, was introduced to help reintegrate the motor industry into the global economy. The aim was to improve the international competitiveness of companies in the industry; enhance the industry's growth through exporting; improve vehicle affordability; improve the industry's highly skewed trade balance; and stabilise employment levels, but succeeded in having the unintended consequence of growing vehicle imports. In this study a literature review is done on studies that were done on governments' policy and the South African motor industry and an empirical study done on a critique of the MIDP as a post-apartheid policy instrument. Of the approximate 500 component manufacturers; only 32 manufacturers participated in this study. South Africa may not have a motor industry in seven to ten years if urgent attention is not paid to increasing local content, gaining certainty on government's support programme for the industry and improving South Africa's cost competitiveness. Imports have grown rapidly and the industry has still not achieved a sufficient volume of production to realise full economies of scale. Another constraint is South Africa's location, remote from major automotive markets. After a long period of heavy protection followed by liberalisation and export support, it is now time for the industry to move towards a balanced growth path on the basis of policies which impose a more neutral incentive structure. This would involve some ongoing protection and assistance for production at low to moderate levels. Under such a scenario, both the domestic market and exports could provide the basis for sustained future growth. / Thesis (M.B.A.)--North-West University, Vaal Triangle Campus, 2010.

The motor industry is one of the leading industries in the South African economy. The MIDP, an import/export complementary arrangement, was introduced to help reintegrate the motor industry into the global economy. The aim was to improve the international competitiveness of companies in the industry; enhance the industry's growth through exporting; improve vehicle affordability; improve the industry's highly skewed trade balance; and stabilise employment levels, but succeeded in having the unintended consequence of growing vehicle imports. In this study a literature review is done on studies that were done on governments' policy and the South African motor industry and an empirical study done on a critique of the MIDP as a post-apartheid policy instrument. Of the approximate 500 component manufacturers; only 32 manufacturers participated in this study. South Africa may not have a motor industry in seven to ten years if urgent attention is not paid to increasing local content, gaining certainty on government's support programme for the industry and improving South Africa's cost competitiveness. Imports have grown rapidly and the industry has still not achieved a sufficient volume of production to realise full economies of scale. Another constraint is South Africa's location, remote from major automotive markets. After a long period of heavy protection followed by liberalisation and export support, it is now time for the industry to move towards a balanced growth path on the basis of policies which impose a more neutral incentive structure. This would involve some ongoing protection and assistance for production at low to moderate levels. Under such a scenario, both the domestic market and exports could provide the basis for sustained future growth. / Thesis (M.B.A.)--North-West University, Vaal Triangle Campus, 2010.

The work described in this thesis addresses two classes of mixed biopolymer systems: (a) starches and sodium caseinate ; (b) gelling seaweed polysaccharides (x-carrageenan - both with and without locust bean gum - agar and alginate) and proteins (gelatin and blood plasma proteins). The viscosity and swelling volume of a 1% potato starch paste in distilled, deionised water is markedly reduced in the presence of caseinate. Similar effects were seen with simple electrolytes suggesting that this occurs as a consequence of a non-specific ionic strength effect. In contrast a 4% maize starch paste in distilled, deionized water undergoes a viscosity and swelling volume increase in the presence of caseinate. However, when pasted in a 0.1M, pH 7.0 phosphate buffer caseinate addition has little effect on the viscosity of the fresh paste and at high concentrations appears to prevent retrogradation on ageing. It is suggested that in buffer caseinate prevents the leaching of starch polysaccharides from the swollen granule and therefore maintains amylose in the granular phase. This is attributable to the high ionic strength of the solvent, allowing caseinate and the starch polysaccharides to phase separate. In water the unfavourable entropy, change due to the uneven distribution of the counter-ions, prevents phase separation and results in an interpenetrating network. Studies on the large deformation stress relaxation behaviour and melting points of 2% carrageenan, 0.5% carrageenan/0.5% locust bean gum (LBG) and 2% agar gels in a variety of solvent media indicate that the inclusions of 0-20% gelatin and 0-5% bovine serum albumin (BSA) give different results depending on both protein and polysaccharide. The main points of this study show that agar/gelatin mixed gel undergoes a distinct phase inversion at 4-7% gelatin levels, which is not seen with the carrageenan gels containing gelatin. Even when 20% gelatin is incorporated into a 2% carrageenan gel the melting point of the gel is unaltered from that of carrageenan alone. In the presence of high levels of BSA the carrageenan/LBG gel undergoes a marked increase in melting point. Investigations using locust bean gums of variable protein content suggests a possible (LBG)protein-BSA interaction since the melting point increases with the LBG protein content. It is shown that carrageenan/LBG gels have clear regions when formed by autoclaving in the presence of blood plasma. This supports the idea of an association between the protein in the insoluble husk and the blood plasma proteins. The interaction mixtures of BSA with sodium alginate at the interface and in bulk solution have been studied through the techniques of microelectrophoresis and ultracentrifugation respectively, to further elucidate the association between denatured proteins above their isoelectric point and anionic polysaccharides. Both techniques clearly show that the macromolecules can associate electrostatically at pH's above the pI of the protein.