A computer program to estimate the weights and volumes of space borne power systems has been written. The program runs on a Zenith Z-100 microcomputer. The weight and volume of the system is calculated based on component data stored in the form of databases. An executive program which provides maximum flexibility to the user in terms of specifying the desired characteristics of the target system has been written. Constraints on the weight and volume of the system may also be specified. Some of the characteristics that may be specified are power requirement, orbit, duty cycles, etc. A complete User's Manual which describes the working methods to create new databases and enter new data, and includes error handling techniques has been generated. The result is an interactive, menu driven, user friendly software package to estimate the parameters of a space borne power system. / M.S.

Masters of Science / Eskom supplies to 95% of South Africa’s energy needs and it primarily comes from coal combustion at their coal–fired power stations. Large volumes of fly ash are generated at these coal-fired power stations as a by-product of the coal combustion process. Fly ash is disposed onto landfills at the respective power stations and these landfills are currently running out of storage space. Subsequently, there are concerning environmental impacts upon the natural water environment resulting from coal mining. More specifically, the discharge of acid mine (AMD) water from historical coal mines impact negatively on the water quality in the nearby rivers and dams in the Witbank area. Therefore, as a consequence of the limited space at fly ash landfills, Eskom has embarked on finding alternative ways to re-use fly ash in different applications such as: soil amelioration and land reclamation, road construction as well as brick and cement development. This study focussed on the feasibility of disposing fly ash into the backfill of historical and future coal mines with the intention to firstly reduce fly ash disposal at existing landfills and secondly to improve the decant water quality of the coal mines in the Witbank area. Globally, fly ash has been successfully used in mine backfilling and AMD treatment in countries such as United States of America and India, due to cementitious properties of their fly ash. However, there is limited knowledge on how South African fly ash would behave under backfilled conditions of opencast coal mines where it will be exposed to acidic water environments. This is due to the fact that South African fly ash is considered a Level 3 type hazardous waste, due to its heavy metal concentrations. This waste classification is unique and the strictest compared to global classifications and these methodologies specify that fly ash should be disposed onto lined waste disposal sites due to the potential leaching of heavy metals from these waste sites. It is important to understand the hydrogeological and hydro-geochemical properties of fly ash over time once it is exposed to acid mine water. Field and laboratory tests were conducted to understand these hydrogeological and hydro-geochemical properties of fly ash. Falling head hydraulic tests were conducted at two existing ash landfill sites to determine the hydraulic conductivity (K) of ash of different age. The results exhibit a decreasing trend in K with increasing age. This is due to the pozzolanic nature of fly ash and secondary mineralization of gypsum which causes the fly ash to harden in the presence of water from irrigation for dust suppression together with precipitation over time. Laboratory testing included the use of constant head Darcy column tests to determine the change in K and geochemical properties of the leachate over time. Natural AMD with a pH of 2.5 and a metal composition was used as influent and the leachate were routinely collected and analysed for metal concentrations. The hydraulic conductivity of the fly ash showed a decreasing trend over time. During the placement of coal ash, the moisture allows pozzolanic reactions to solidify the coal ash and lowers the K, towards 10-1 m/d, relative to fresh ash. Secondary mineralization of calcium minerals, in the coal ash contributes to a further decrease in the K, by another order of magnitude from 10-1 m/d towards 10-2 m/d. Sulphate and iron minerals from the AMD also played a major role in the decreasing K as they accumulate in void spaces and having a clogging effect, decreasing the K to 10-3 m/d. The alkaline nature of the coal ash initially neutralizes the acidic levels of AMD from an inflow pH = 2.5 to an outflow pH = 11. Acidification of the outflow towards a pH = 4 was observed, due to large volumes of AMD (>80 000 mL) flowing through short coal ash columns. The K decreased to 3 orders of magnitude, from an initial 10-1 m/d to 10-3 m/d, with the AMD iron (>150 mg/L) and sulphate concentration (>2000 mg/L) playing the dominant role in reducing the hydraulic conductivity. From the geochemical leach test results, it was observed that most of the leachate water was of a better quality than the influent AMD water quality. The outflow pH (pH = 11 to pH = 4) was higher than the pH of the inflow AMD (pH = 2.5). Overall EC reduced in discharge compared to inflow AMD (ECinflow: 535 – 545 mS/m versus ECoutflow: 350 – 490 mS/m), although Na and K in the leachate exhibited higher concentrations (10+2 mg/L) compared to the AMD inflow concentrations (10+1 mg/L). However, most of the other chemical elemental concentrations such as Fe (10-2 – 10+1 mg/L), Si (10-2 – 100 mg/L), Al (10-2 – 10+1 mg/L), Mn (10-2 – 10+1 mg/L), Cr (10-3 – 100 g/L) and SO4 (10+2 – 1+3 mg/L) in the discharge showed lower concentrations when compared to the inflow Fe (10+2 mg/L), Si (100 mg/L), Al (10+1 mg/L), Mn (10+1 mg/L), Cr (10-2 mg/L) and SO4 (10+3 mg/L) concentrations. These results show how fly ash backfill may impact on the current coal mining environment. Overall, the laboratory hydraulic conductivity and geochemical testing showed promising results for fly ash backfilling. Based on this research, fly ash can be used to alter the existing coal mining environment as it is currently known in the Witbank area. The topography, hydraulic conductivity and the water table within the backfill can be altered to improve decant water quality of ash backfilled coal mines.

Submitted by ROXANE LOPES DE MELLO null (mellodias.slp@gmail.com) on 2017-03-03T13:08:45Z No. of bitstreams: 1 Tese de Doutorado Roxane Lopes de Mello.pdf: 5260374 bytes, checksum: 418c914b4ab80e80c708b497661c5e26 (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-03-08T17:09:55Z (GMT) No. of bitstreams: 1 mello_rl_dr_guara.pdf: 5260374 bytes, checksum: 418c914b4ab80e80c708b497661c5e26 (MD5) / Made available in DSpace on 2017-03-08T17:09:55Z (GMT). No. of bitstreams: 1 mello_rl_dr_guara.pdf: 5260374 bytes, checksum: 418c914b4ab80e80c708b497661c5e26 (MD5) Previous issue date: 2017-01-11 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O acesso à energia elétrica é requisito básico de cidadania e de desenvolvimento econômico e, no Brasil, a principal fonte de geração de energia são as hidrelétricas. Entende-se que a geração de energia hidrelétrica através de centrais geradoras de pequeno porte é sustentável, porém, para averiguar essa sustentabilidade se faz necessário avaliar as situações de vulnerabilidade socioambiental na área de influência do empreendimento. O principal objetivo deste trabalho foi analisar as áreas em situação de vulnerabilidade socioambiental na área de influência de uma central geradora de pequeno porte hipotética na bacia hidrográfica do rio do Chapéu, localizada no município de São Luiz do Paraitinga, Estado de São Paulo como área de estudo de caso para compreensão das inter-relações das vulnerabilidades socioambientais. A metodologia empregada utilizou ferramentas de análise espacial de dados ambientais e sociais da área de estudo e aborda uma análise multicriterial baseada na classificação contínua e na técnica de comparação pareada AHP (Analytical Hierarchy Process), incorporados ao SIG completo denominado SPRING v. 4.3.3 (Sistema de Processamento de Informações Georreferenciadas), para a obtenção do mapa de Índice de Vulnerabilidade Socioambiental – IVSA. Concluiu-se que há fortes coincidências entre os espaços susceptíveis a processos de vulnerabilidade físico-ambiental e os espaços que apresentam os piores indicadores sociais, que são agravados por um fator antrópico, o uso do solo. Os resultados deste trabalho expressam o ponto de partida para análises mais aprofundadas da vulnerabilidade socioambiental da área de influência de centrais geradoras de pequeno porte sendo necessário o planejamento de ações mitigadoras, dessa vulnerabilidade, em busca de alcançar a sustentabilidade do empreendimento. / The access to electricity is a basic requirement of citizenship and economic development, and in Brazil, the main source of energy is from hydroelectric stations. It is understood that the hydroelectric energy generation through small-scale power is sustainable, however, to verify this sustainability it is necessary to assess the socio-environmental vulnerability situations in the influence area of the enterprise. The main objective of this work was to analyze the socioenvironmental vulnerability in the influence area of a hypothetical small power generating station in the hydrographic water parting of the Chapéu river, located in the city of São Luiz do Paraitinga, State of São Paulo, as an area of a study case to understand the interrelationships of socio-environmental vulnerabilities. The methodology used spatial analysis tools of environmental and social data of the study area and addresses a based multicriteria analysis on continuous classification, the AHP (Analytical Hierarchy Process) and the paired comparison technique, incorporated into the complete GIS called SPRING v. 4.3.3 (Georeferenced Information Processing System), to obtain the Socio-Environmental Vulnerability Index Map – IVSA. It was concluded that there are strong coincidences between the susceptible spaces to processes of physical-environmental vulnerability and spaces that present the worst social indicators, which are aggravated by an anthropic factor, the ground use. The results of this work express the starting point for deep analyzes of the socio - environmental vulnerability at the influence area of small - scale generating stations, being necessary the planning of mitigating actions of this vulnerability, in sense of achieving the enterprise’s sustainability. / CNPq: 153240/2012-1

One technology that makes concrete without cement and does not have the associated carbon footprint is geopolymer concrete. This technology utilizes waste fly ash from power stations and mixes it with activating chemicals to form a binder with similar or better properties than cement. Not only does this technology directly reduce carbon emissions by replacing cement it also utilizes the waste bi-product from power stations and prevents it from going to landfill. Concrete is composed of coarse aggregates, sand and cementitious paste. It seemed possible to make geopolymer concrete from 100% waste. The aggregates would come from recycled concrete and hard brittle bottom ash from power stations, the sand would come from foundries and the fly ash binder would also come from the same power station as the bottom ash. All of these materials are waste and would all be dumped in landfill. Where would one find all these waste materials in one place? The industrial suburb of Kwinana outside Perth is home to a large number of industries producing all these wastes. To find products that have a specification that these materials would suit was a material with a relatively low specification, one such specification is the concrete masonry units’ specification. For this to be adopted the mix design would then have to be altered to a drier type mix without any slump. As recycling facilities do not make a range of products it was decided to crush the aggregates in the laboratory specifically for this research and to blend all the waste materials. Numerous combinations were blended, analysed and assessed to establish which blends would best suit the aims and scope of this research. Eventually three blends were selected that encompassed all the waste products. / To find the right mix design proved challenging as these masonry products generally require a mix to have zero slump. It was decided to test across all the known and analysed water to geopolymer solids ratios for each of the mixes and establish the best mix based on compressive strength, workability and slump A known mix design based on research into low calcium Class F geopolymer concrete, developed at Curtin University using natural aggregates, was applied to these selected recycled waste mix designs. The benefit was to be able to compare the results of this research to a known result. Flash setting, an unknown phenomenon in geopolymer concrete, did occur in the low water mixes, but in spite of this, geopolymer concrete was successfully manufactured. The compressive strengths were substantially lower than those of the design mix and more research is required in this regard, however an indirect relationship was observed between the amount of bottom ash and the compressive strength. The high degree of LOI (loss of ignition) in both ashes, porosity of recycled aggregates, angularity, degree of fineness of the fines and flash setting are all possible factors influencing the properties of the geopolymer concrete. More research is recommended in a number of these areas to be able to understand and develop this technology further in order to make this a practical and robust technology in the quest to find solutions to our warming planet and our changing climate.

<p><strong>AIM</strong>: As global warming is a fact and the consumption of energy is continuously increasing, alternative sourcing of energy is a must. The use of oil and coal for heating is limited due to it is nature resource which is also limited. Everyone will be forced to evaluate their own usage of energy and look into the alternatives of how to be a part of solving this global issue. For many, alternatives such as sun panels and wind power stations could be an alternative power source.</p><p> </p><p>Today, there is only a limited availability in Sweden of small sized wind power stations and only small local producers or importers that sell the equipment – mostly through internet based market communications.</p><p> </p><p><strong>Method</strong>: The theoretical approach to this thesis is based on the MIO model in combination with several other models and tools such as, PESTEL, Marketing Mix, SWOT, Porter’s five forces, EVC and STP.</p><p> </p><p><strong>Result & Conclusions</strong>: There is a market for small wind power stations between 5 – 50 kW in Sweden.</p><p>The biggest reason why the market segment exist and will increase is due to continuously increasing energy prices and that wind power stations of this size are permitted to be connected directly to household consumption.</p><p> </p><p><strong>Suggestions for future research</strong>: How are other energy complements like solar panels influenced? What governmental decisions affect the business of small wind power stations?</p><p> </p><p><strong>Contributions to the thesis</strong>: Success in this segment requires a different approach to product offering than what the current competition is doing.</p>

AIM: As global warming is a fact and the consumption of energy is continuously increasing, alternative sourcing of energy is a must. The use of oil and coal for heating is limited due to it is nature resource which is also limited. Everyone will be forced to evaluate their own usage of energy and look into the alternatives of how to be a part of solving this global issue. For many, alternatives such as sun panels and wind power stations could be an alternative power source.   Today, there is only a limited availability in Sweden of small sized wind power stations and only small local producers or importers that sell the equipment – mostly through internet based market communications.   Method: The theoretical approach to this thesis is based on the MIO model in combination with several other models and tools such as, PESTEL, Marketing Mix, SWOT, Porter’s five forces, EVC and STP.   Result &amp; Conclusions: There is a market for small wind power stations between 5 – 50 kW in Sweden. The biggest reason why the market segment exist and will increase is due to continuously increasing energy prices and that wind power stations of this size are permitted to be connected directly to household consumption.   Suggestions for future research: How are other energy complements like solar panels influenced? What governmental decisions affect the business of small wind power stations?   Contributions to the thesis: Success in this segment requires a different approach to product offering than what the current competition is doing.

Masters diploma The purpose of the masters diploma work is analysis of efficiency of hydrogen power stations. Based on the data collected in the work, current exploration directions in hydrogen energetic and kinds of fuel cells can be reviewed, as well as results of a laboratory tests, performed with laboratory fuel specimens. Hydrogen power station, as a station of the future, is currently in the developing phase. Fuel cell and solar panel battery types and efficiency factors are examined, considering fuel cells and solar panel batteries, as primary supply source, are major components in the power station. The most important thing in operation of the power station is it‘s rate of efficiency. The attempt will be made to determine common efficiency value of such power station. It will be possible to compare received results with those provided in the specified literature.

M.Ing. / This dissertation deals with the implementation of a Reliability Basis Optimisation Process for Eskom’s fossil fired Power Stations. This study comes about as a result of the situation that Eskom currently finds itself in. Eskom currently has a generating capacity of 41 000MW. It supplies 95% of South Africa’s power requirements and 45% of Africa’s power requirements. With the unprecedented economical growth that South Africa has experienced in the last five years, coupled with the economic recession of 2008/2009, Eskom has found itself in a precarious position in terms of power delivery. Eskom’s request for a 45% tariff increase in its Multi Price Determination (MYPD2) application to NERSA was turned down and a figure of 25% was awarded. Eskom’s current reserve margin is currently lies as less than 10%. With the funding restrains it now becomes difficult to replace machinery as it fails. The focus now shifts of carrying out effective maintenance. Eskom established the Asset Management Department with a view to ensure that the right maintenance was carried out. Within the Asset Management Department the Reliability Basis Optimisation (RBO) Process was established. The aim of the RBO stream is to improve the reliability and availability of the fossil fired Power Station. This dissertation looks at how the RBO process was developed and rolled out to the Power Stations. It also gives a brief overview of the Asset Management Improvement process to which the RBO process is the backbone.

Maintaining and improving innovation is vital to any organisation.There are many challenges organisations are faced with, both internally and externally when it comes to maintain and improving innovation. Eskom is such an organisation. The employees, both non-managerial and managerial, of Eskom are faced with various challenges in their daily activities. The quest for innovation advantages requires increased creativity to assist employees in adopting an intrapreneurial outlook to provide proactive solutions. Intrapreneurship is an autonomous process. Eskom which bulk suppliers South Africa mission is to provide electricity reliably at a low cost to all South African. This seems less reachable with high operating cost, slow capacity growth and aging infrastructure. This study focused and contributed to the innovation environment of Eskom, with the area of study being confined within the Eastern Cape. The study objectives sought to review Eskom Distribution’s business plan and innovation policy, while identifying if employees have intrapreneurial trait, if organisational culture, system and managerial styles are conducive for intraprenuership, if the external environment will promote intrapreneurship within the organisation, and which ideas have best adoption rates of innovation within the organisation, these factors may hinder the success of innovation in the organisation, based on the theoretical findings of the literature study. Employees, at both managerial and non-managerial levels participated in a research study. The research instrument used comprised of questions that covered the various objectives listed above. This provided the basis for a quantitative study to be done. Using statistical methods to identify any special relationships or trends, the research was conducted and recommendations were made based on the objectives of this study in relation to the organisation under study, Eskom Distribution, Eastern Cape Operating Unit. Based on the findings, recommendations to improve innovation, through intrapreneurship methods were made.

Thesis (PhD (Mechanical Engineering))--University of Stellenbosch, 1990. / Leaves printed on single pages, preliminary pages i- viii and numbered pages 1-1-R5. Includes bibliography, list of tables and figures and list of appendices. Digitized at 330 dpi black and white PDF format (OCR),using KODAK i 1220 PLUS scanner. / ENGLISH ABSTRACT: A numerical procedure for predicting the effect of inlet flow distortions on the performance of axial flow fans is proposed. The study is aimed specifically at fans of low solidity and low hub-to-tip ratios, which have attained some importance with the advent of large directly air-cooled power stations in certain arid regions of the world. The numerical model is an extension to cylindrical polar coordinates of the SIMPLEN algorithm that has been developed by the author previously. The algorithm is implemented in a computer code, FLOVAX, which solves the incompressible Navier-Stokes equations, augmented by the k-Ɛ model of turbulence, on a computational domain that is aligned with the cylindrical polar coordinate system. Several relatively simple flow problems are solved to verify the code: laminar stagnation flow, laminar flow near a rotating disk, turbulent flow near a propeller, turbulent flow through an abrupt axisymmetric expansion, and turbulent swirling flow in an annulus. Good agreement is obtained between the numerical solutions and the corresponding analytical, empirical or published experimental and numerical results. Some experimental results are also presented: measurements of shaft power, volume flow rate and static pressure rise were taken in a setup comprising an axial flow fan mounted in the wall of a wind tunnel. The wind tunnel was used to provide flow across the fan intake, thus establishing distorted inflow conditions. Detailed measurements of the velocity and static pressure distributions in the duct downstream of the fan rotor were also performed. It is clear from the results that flow across the intake of the test fan has a detrimental effect on its performance in that an increased amount of power is necessary to deliver the same flow rate as with no crossflow. In the numerical predictions, blade element theory is used to model the thrust and torque exerted by the fan blades on the air. The numerical results generally confirm the results of the experiment, although the increase in power is underestimated: an increase of only approximately half of the measured increase is predicted. Several recommendations for improvement of the numerical procedure are made. / AFRIKAANSE OPSOMMING: 'n Numeriese prosedure vir die voorspelling van die invloed van versteurings in inlaatvloei op die werking van aksiaalwaaiers word daargestel. Die studie is spesifiek gemik op waaiers van lae soliditeit en lae lempunt-tot-naafverhoudings. Waaiers van hierdie tipe het belangrikheid verwerf sedert die onlangse totstandkoming van groot lugverkoelde kragstasies in sekere droe werelddele. Die numeriese model is 'n uitbreiding na silindriese poolkoordinate van die SIMPLEN-algoritme wat voorheen deur die skrywer ontwikkel is. Die algoritme word geimplementeer in 'n rekenaarkode, FLOVAX, wat die onsamedukbare Navier-Stokes-vergelykings, aangevul deur die k-Ɛ-turbulensiemodel, oplos op 'n berekeningsgebied wat saamval met die silindriese poolkoordinaatstelsel. Verskeie relatief eenvoudige vloeiprobleme word opgelos ter verifikasie van die kode: laminere stagnasievloei, laminere vloei op 'n roterende skyf, turbulente vloei deur 'n propeller, turbulente vloei deur 'n aksiaalsimmetriese vernouing, en turbulente roterende vloei in 'n annulus. Goeie ooreenstemming tussen die numeriese oplossings en die ooreenstemmende analitiese, empiriese of gepubliseerde eksperimentele en numeriese resultate is verkry. Eksperimentele resultate word ook aangebied: metings van asdrywing, volumevloei en statiese drukstyging is geneem in 'n opstelling wat bestaan het uit 'n aksiaalwaaier wat in die wand van 'n windtonnel gemonteer is. Die windtonnel is gebruik om versteurde-invloei-toestande te genereer in die vorm van dwarsvloei oor die waaier-inlaat. Snelheids- en statiese drukverdelings in die kanaal stroom-af van die waaierrotor is ook gemeet. Dit blyk duidelik uit die resultate dat die dwarsvloei oor die inlaat van die toetswaaier 'n nadelige uitwerking het op die werking daarvan in die opsig dat meer drywing nodig is om dieselfde vloeitempo te handhaaf as wat die geval is sonder dwarsvloei. Vir die numeriese voorspellings word van lem-element-teorie gebruik gemaak om die stukrag en draaimoment wat deur die waaier op die lug uitgeoefen word, te modelleer. Die numeriese resultate bevestig oor die algemeen die eksperimentele resultate, alhoewel die drywingstoename onderskat word met sowat die helfte van die gemete toename. Verskeie aanbevelings ter verbetering van die numeriese prosedure word gemaak.