Global ETD Search

41	An Investigation of the Storage Stability of Auger and Entrained Flow Reactor Produced Bio-oils Mohammad, Javeed 01 May 2010 (has links) This project is primarily focused on improving the storage stability of bio-oils or pyrolysis oils by varying feedstock, reactor, and storage conditions. Pyrolysis oil is a complex medley of oxygenated chemicals (aliphatic and aromatic) that are well known to undergo unstable polymeric reactions (auto-catalyzed) if suitable additives are not utilized. These reactions can be severely detrimental to the long-term storage stability of pyrolysis oils. Hence, a detailed investigation was conducted in four phases namely: 1) pyrolysis oil production 2) additive prescreening 3) concentration optimization and 4) stability testing. During the first phase a lab-scale semi-continuous auger reactor is utilized to produce 16 pyrolysis oils. The reactor variables include pyrolysis temperature and vapor residence time. The feed stocks include pine wood, pine bark, oak wood, and oak bark. During the second phase a range of chemical additives (26) are prescreened to obtain three best performing additives. Anisole, glycerol, and methanol are consequently utilized to perform concentration optimization studies during the third phase. Viscosity, water content, and pH of pyrolysis oils are timely measured to assess the accelerated storage stability of pyrolysis oils during the phases 2-3. During the fourth phase, pyrolysis oils produced from three different reactor systems (lab-scale auger, large-scale auger, and entrained flow) were tested for their storage stability. Viscosity, water content, pH, density, and acid value are timely measured to assess the ambient and accelerated storage stability of pyrolysis oils during phase 4. Extrinsic variables such as light and filtration are utilized during the experimental testing of phase 4. The rheological data (Newtonian/non-Newtonian) enhanced the understanding of pyrolysis oil storage stability both qualitatively and quantitatively. The stability performance of a chemical additive is very much dependent on the concentration and its organic functional group. Consequently, alcohols fared above all the other functional groups in stabilizing the pyrolysis oils. Glycerol is observed to have special blending and homogenizing properties compared to all other additives. Feedstock seems to be the single most important factor affecting storage stability of pyrolysis oils. Consequently, pine wood resulted in the most stable pyrolysis oil whereas pine bark resulted in the least stable pyrolysis oil. auger fluidized/entrained flow lignocellulosic pyrolysis bio-oil storage stability rheology Karl Fisher additive prescreening modeling concentration optimization Biomass chemicals--Storage Pyrolysis--Research. Biomass energy. Renewable natural resources--Research Biodiesel fuels--Storage
42	The economics of gold mining taxation Mangondo, Kismore 30 June 2006 (has links) Currently the gold mining industry is taxed differently to other industries. It is taxed on a two-tier system. The nature of the gold mining tax formula encourages the mining of marginal gold ores. Firms that are involved in the mining of gold are subjected to a "tax tunnel", which is a tax free revenue portion. This is against the equity principle of taxation because it separates companies on the basis of what they produce and not on the basis of income generated. The South African government is in the process of implementing a revenue-based royalty system. The majority of firms in the gold mining industry feel that for the benefit of economic growth the government must consider implementing a profit-based royalty system. This study analyses the gold mining tax formula in comparison to the flat rate tax. It also analyses the reasons for the differential treatment of the gold mining industry. / Economics / M.Comm. Gold mining tax formula Economic importance Tax revenue Gold production Taxation Non-renewable resources Renewable resources Natural resources Economics of gold mining Gold mining taxation 336.27833827410968 Natural resources -- South Africa
43	Obtenção e caracterização de compósito verde de casca de pinhão e poliuretana derivada do óleo de mamona / Preparation and characterization of pinhão husk and polyurethane derived from castor oil green composite Protzek, Giuliana Ribeiro 13 December 2017 (has links) Compósitos verdes são caracterizados por possuir matriz polimérica e reforço derivado de fontes naturais. Polímeros derivados do petróleo não são biodegradáveis e possuem solventes orgânicos na sua composição. Solventes orgânicos são tóxicos e poluentes. A poliuretana derivada do óleo de mamona é derivada de fonte renovável, biodegradável e não possui solventes orgânicos em sua composição. A casca de pinhão é um resíduo do pinhão, semente do pinheiro de Paraná. O objetivo desse trabalho é desenvolver e caracterizar o compósito de casca de pinhão com PU derivada do óleo de mamona. A fibra foi caracterizada quimicamente, por FTIR, TGA e MEV. A PU foi caracterizada por ensaio de resistência à flexão, FTIR e TGA e os compósitos, por testes de densidade, absorção de água, inchamento em espessura, resistência à flexão de três pontos, FTIR e TGA. A superfície da fratura foi avaliada por MEV e a homogeneidade dos compósitos por perfil de densidade e raios-X. O compósito de 35%PU apresentou resistência à flexão de 51,55 MPa, densidade de 1018 kg/m³, absorção de água em 24 horas de 7,95% e inchamento em espessura em 24 horas de 5,36%. O material apresenta propriedades mecânicas apropriadas para uso em mobiliário e artesanato. / Polymeric composites reinforced with natural fibers are denominated green composites. Polymers comes from petroleum source, a non-biodegradable material and has volatile organic compounds, VOC, in its composition. Organic solvent are toxics and pollute the environment. The Polyurethane derived from castor oil is polymer produced from renewable sources, biodegradable material and there are no VOC in its composition. Araucária pine nut shell is a residue from its Araucaria pine seed. The aim of this work is to develop and characterize composites of pine nut shell with polyurethane derived from castor oil. The fiber was chemically characterized, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). PU was characterized by flexural strength, FTIR and TGA and composites was characterizes by density test, water absorption and swelling in thickness, flexural strength, FTIR, TGA. SEM evaluated the fracture surface and X-ray and vertical density profile verified the composites homogeneity. 35%PU composites presented flexural strength of 51,55 MPa, density of 1018 kg/m³, 7,95% of 24h water absorption and 5,36% of 24h swelling in thickness of. The material exhibits properties suitable for use in furniture and handicrafts. Poliuretanas Mamona Pinhão - Subprodutos Termogravimetria Espectroscopia de infravermelho Recursos naturais renováveis Engenharia mecânica Polyurethanes Castor beans Pinyon pines Thermogravimetry Spectroscopy, Infrared Renewable natural resources Mechanical engineering Engenharia Mecânica
44	The economics of gold mining taxation Mangondo, Kismore 30 June 2006 (has links) Currently the gold mining industry is taxed differently to other industries. It is taxed on a two-tier system. The nature of the gold mining tax formula encourages the mining of marginal gold ores. Firms that are involved in the mining of gold are subjected to a "tax tunnel", which is a tax free revenue portion. This is against the equity principle of taxation because it separates companies on the basis of what they produce and not on the basis of income generated. The South African government is in the process of implementing a revenue-based royalty system. The majority of firms in the gold mining industry feel that for the benefit of economic growth the government must consider implementing a profit-based royalty system. This study analyses the gold mining tax formula in comparison to the flat rate tax. It also analyses the reasons for the differential treatment of the gold mining industry. / Economics / M.Comm. Gold mining tax formula Economic importance Tax revenue Gold production Taxation Non-renewable resources Renewable resources Natural resources Economics of gold mining Gold mining taxation 336.27833827410968 Natural resources -- South Africa
45	COncepts and costs for the maintenance of productive capacity: a study of the measurement and reporting of soil quality O'Brien, Patricia Ann, patricia.o'brien@rmit.edu.au January 1999 (has links) This thesis studies the role accounting plays in the monitoring and reporting of soil quality in one sector of the agricultural industry, broadacre farming. A survey was conducted with broadacre farmers in the Loddon Catchment, Victoria, Australia. The primary aim was to determine the effectiveness accounting plays in providing information to decision makers relative to the productive capacity in soil quality and not just on profits. The capital asset in this study was defined as soil quality. Soils and soil quality in particular, are major elements in determining land value. The concern is decisions are being made by potential buyers and other decision makers, particularly policy makers, with regards to soil quality on the basis of incomplete and often misleading information. It is proposed that a major reason is due to the fact that different participants in the agricultural and accounting industries require and use different information. The accounting systems used by farmers are those that have been developed for the manufacturing sector which may not be appropriate for managing long-term, complex resources such as soil. The farmers themselves did not find formal accounting reports useful for decision making because these reports are based on uniform standards and market prices. The topic of soil quality and land degradation is viewed from two perspectives. In one perspective, the proprietary view; the accounting emphasis is on the ownership of assets and the change, both in income and capital, in these assets over time. In this case the accounting equation is seen as assets - liabilities = equities. The proprietor takes all the risk. A more recent perspective in accounting, the entity view, emphasises the assets whether financed from equity or debt and where the accounting equation is seen as assets = equities. The emphasis changes to the income flow from these assets and more interest is shown in current market prices as a reflection of the future value of these assets Profit is not necessarily a good indicator of what farmers are doing for their capital asset. There needs to be greater emphasis on costs undertaken for the conservation of soil. Those costs should be considered an investment and put into the balance sheet and not the profit and loss statement. The major finding of study demonstrates that decision making groups have different Activity-based costing Agricultural conservation Agricultural ecology Assets (Accounting) Capital assets Current liabilities Debt Environmental responsibility Family farms Farm business management Farm risks Farming and rural systems economics Farms Income forecasting Land degradation Liabilities Natural resources Nonrenewable natural resources Prices Productivity accounting Renewable natural resources Risk management Salinity Soils Soil conservation Soil degradation Soil economic aspects Soil ecology Soil fertility Soil productivity Soil profiles Soils Quality Soil structure Stocks Wealth Wives Women

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