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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Microbial Pretreatment of Lignocellulosic Biomass with <i> Ceriporiopsis Subvermispora </i> for Enzymatic Hydrolysis and Ethanol Production

Wan, Caixia 21 March 2011 (has links)
No description available.
62

Do Oil Companies aquire Alternative Energy Patents to Limit Technological Innovation, in order to Maintain Economic Advantage in Fossil Fuels

Sims, George G. 25 November 2002 (has links)
This paper addresses the charge made by environmental groups that oil companies, since the 1970's, have been acquiring alternative energy patents, to restrict these technologies from reaching the market. The purpose of these restrictions was to protect profits from oil, natural gas and coal. In addressing this charge, I reviewed the literature to ascertain if any conclusive study had been performed to substantiate this charge. To date, none had been performed. While no conclusive study had been performed to support the environmentalist position, an evaluation of economic theory along with an examination of actual U.S. Patent Office data strongly contradicts the environmentalist view. / Master of Arts
63

Telemetry System for the Solar Miner VII

Guenther, Clinton, Mertens, Robert, Lewis, Adam 10 1900 (has links)
ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / This paper describes a telemetry system used in the Missouri S&T solar car, which competed in the American Solar Challenge. The system monitors parameters of a number of the on-board electronic and mechanical systems, and also the activities of the vehicle driver. This data is transmitted to a lead vehicle, where the support team analyzes the performance in real-time to optimize the vehicle's performance. In previous vehicles the data was displayed using a LabVIEW based user interface. In this work we will describe a custom software solution, which provides the team with additional flexibility to display and analyze the data.
64

Water consumption for steam methane reforming hydrogen plants in Edmonton, Canada

Shah, Jignesh 13 July 2016 (has links)
<p> Traditional engineering and financial assessments are limited not only to consideration of currently internalized costs, but also often lack consideration of new or current externalities during the life of the new system. The goal of this thesis is to provide a methodology that integrates sustainability assessment with the traditional assessments, thereby allowing the assessment and optimization of the total overall costs. The proposed method is applied for the steam methane reforming (SMR) plants operated by Air Products in Edmonton, Canada where the boiler feed water for hydrogen manufacturing is produced using the polished effluent from the local municipal wastewater treatment plant. The softening of the feed water to Reverse Osmosis (RO) system is proposed (after evaluating the several options) to improve the recovery for the current RO system from 75% to 95%. The overall costs were estimated for comparison of the current and proposed systems.</p><p> The production of hydrogen via SMR highlights the complexities of the sustainability assessment. While hydrogen may be considered a renewable transportation fuel, depending on whether the fossil natural gas can be replaced with renewable biogas or via electrolysis of water using renewable energy, it is reliant on the availability of water. However, water is a scarce resource that is also essential for basic human survival and ecological needs. As the population of the world increases, alternative water sources need to be explored, which may require more energy in the processing of such water to potable grade. </p><p> The results show that the proposed RO feed softening via Ion Exchange (IX) can improve RO recovery up to 95%. The financial assessments based on literature prices and cost factors show that the current operating cost can be reduced up to ~20% by improving RO recovery to 95% with ~75% probability for cost reduction at 95% recovery. When the capital costs are accounted for, NPV-based analyses show that for 95% recovery more than 20% IRR (if spare vessels are available for refurbishment) could be achieved.</p><p> Environmental assessments (Life Cycle Assessment method using SimaPro v7.3 following ISO 14040-44 standards) show that 1.12 x 10<sup>-3</sup> ReCiPe Endpoints impact for current RO operation at 75% recovery can be reduced by ~8% when 95% RO recovery is achieved via the proposed system. Due to the need for increased NaCl salt for regeneration of resins in the proposed system, the environmental impacts increased for metal depletion and ionizing radiation impact categories, unlike the other impact categories. The GHG emissions could be reduced by ~10% (after accounting for 10%-30% probability) for 95% RO recovery with the reduction from the reduced consumption of inputs. Similarly, the life cycle water depletion impacts can be reduced by ~10% (after accounting for 30%-65% reduction probability) from the current 1.75kg water depletion per kg of BFW produced. Water Footprint Assessment (WFA) as per the Ridoutt &amp; Pfister method shows that when accounted for local water stress, during the worst month, the blue water footprint increases from 1.75kg/kg BFW to 63.9kg/kg BFW, in addition to ~0.08kg/kg BFW greywater footprint.</p><p> The social assessment shows mixed results with lower employment, employee development, corporate philanthropy, environmental "protect" spend and R&amp;D spend due to reduced overall consumptions for the 95% recovery option. The other social impact categories were improved for 95% recovery. The overall cost (estimated as the sum of the internally normalized social costs) were 3.0 units with up to 35% reduction potential.</p><p> The results of the case study show that IX feed softening has potential to not only reduce the environmental and social costs, but also meet the financial constraints. Also, this highlights that an integrated sustainability assessment method that evaluates and combines all three aspects of sustainability - environment, social and economic - could be developed. The proposed method as presented needs further development. Among other things, the lack of availability of robust social inventory database significantly hinders the development and adoption such integrated methods. The application of the method to additional case studies would be a good next step.</p><p> This exercise has highlighted that the value and benefits of overall cost estimates are beyond those of policy making by the regulatory agencies. Sustainability minded companies could benefit from having environmental and social goals along with the financial targets as they understand the risks from inadequate performances in any of these aspects. However, these goals are typically on a gate-to-gate basis and independent of each other; thereby, creating the potential for shifting burdens in the value chain and not obtaining the full benefits of risk mitigation. The assessment using the overall cost approach at life cycle basis is essential for industry in not only risk mitigation, but also opportunity identification at an early stage.</p>
65

Nonlinear Robust Control of Permanent Magnet Synchronous Motors With Applications to Hybrid Electric Vehicles

Reitz, Max A. 20 July 2016 (has links)
<p> Environmental concerns are driving the automotive industry towards more sustainable and efficient forms of transportation such as electric vehicles. The electric drivetrains present in the various types of electric vehicles are much more efficient than traditional internal combustion engine drivetrains and produce fewer greenhouse gases. The most popular type of motor used in electric vehicle drivetrains is the permanent magnet synchronous motor. This can be attributed to its inherent high power density, large torque to weight ratio, and high reliability and efficiency. Advanced control techniques for permanent magnet synchronous motor drives must be developed in order to meet the high performance and efficiency demands of modern electric vehicles. Application of the nonlinear control method known as sliding mode control is the focus of this work. Both first order and higher order sliding mode methods are considered. These control methods provide robustness to modeling inaccuracies, internal parameter variations, and external disturbances. In addition to permanent magnet synchronous motors, the sliding mode control methods are also applied to the buck-boost type DC-DC converter. DC-DC converters have found extensive applications, ranging from consumer electronics to electric vehicles and smart grid synchronization. Computer simulation studies verify the efficacy of the proposed control techniques.</p>
66

Models for a carbon constrained, reliable biofuel supply chain network design and management

Marufuzzaman, Mohammad 01 October 2014 (has links)
<p> This dissertation studies two important problems in the field of biomass supply chain network. In the first part of the dissertation, we study the impact of different carbon regulatory policies such as carbon cap, carbon tax, carbon cap-and-trade and carbon offsetmechanism on the design and management of a biofuel supply chain network under both deterministic and stochastic settings. These mathematical models identify locations and production capacities for biocrude production plants by exploring the trade-offs that exist between transportations costs, facility investment costs and emissions. The model is solved using a modified L-shaped algorithm. We used the state of Mississippi as a testing ground for our model. A number of observations are made about the impact of each policy on the biofuel supply chain network. </p><p> In the second part of the dissertation, we study the impact of intermodal hub disruption on a biofuel supply chain network. We present mathematical model that designs multimodal transportation network for a biofuel supply chain system, where intermodal hubs are subject to site-dependent probabilistic disruptions. The disruption probabilities of intermodal hubs are estimated by using a probabilistic model which is developed using real world data. We further extend this model to develop a mixed integer nonlinear program that allocates intermodal hub dynamically to cope with biomass supply fluctuations and to hedge against natural disasters. We developed a rolling horizon based Benders decomposition algorithm to solve this challenging NP-hard problem. Numerical experiments show that this proposed algorithm can solve large scale problem instances to a near optimal solution in a reasonable time. We applied the models to a case study using data from the southeast region of U.S. Finally, a number of managerial insights are drawn into the impact of intermodal-related risk on the supply chain performance.</p>
67

Virtual Solar Energy Center| A Case Study of the Use of Advanced Visualization Techniques for the Comprehension of Complex Engineering Products and Processes

Ritter, Kenneth August, III 01 December 2016 (has links)
<p> Industry has a continuing need to train its workforce on recent engineering developments, but many engineering products and processes are hard to explain because of limitations of size, visibility, time scale, cost, and safety. The product or process might be difficult to see because it is either very large or very small, because it is enclosed within an opaque container, or because it happens very fast or very slowly. Some engineering products and processes are also costly or unsafe to use for training purposes, and sometimes the domain expert is not physically available at the training location. All these limitations can potentially be addressed using advanced visualization techniques such as virtual reality. This dissertation describes the development of an immersive virtual reality application using the Six Sigma DMADV process to explain the main equipment and processes used in a concentrating solar power plant. The virtual solar energy center (VEC) application was initially developed and tested in a Cave Automatic Virtual Environment (CAVE) during 2013 and 2014. The software programs used for development were SolidWorks, 3ds Max Design, and Unity 3D. Current hardware and software technologies that could complement this research were analyzed. The NVIDA GRID Visual Computing Appliance (VCA) was chosen as the rendering solution for animating complex CAD models in this application. The MiddleVR software toolkit was selected as the toolkit for VR interactions and CAVE display. A non-immersive 3D version of the VEC application was tested and shown to be an effective training tool in late 2015. An immersive networked version of the VEC allows the user to receive live instruction from a trainer being projected via depth camera imagery from a remote location. Four comparative analysis studies were performed. These studies used the average normalized gain from pre-test scores to determine the effectiveness of the various training methods. With the DMADV approach, solutions were identified and verified during each iteration of the development, which saved valuable time and resulted in better results being achieved in each revision of the application, with the final version having 88% positive responses and same effectiveness as other methods assessed.</p>
68

Numerical and experimental investigation of a microalgae cultivation system for wastewater treatment and bioenergy production

Amini, Hossein 01 December 2016 (has links)
<p> Over the past decade, there has been a revival in algal research and attempts at large scale cultivation for bioenergy production. Among various types of microalgae culturing systems, Open Raceway Ponds (ORP) are considered as an economic system for large-scale microalgae cultivation. In order to improve the algal growth and productivities in ORPs, it is very important to understand the effects of design parameters and operating conditions on mixing and light distribution patterns. The goal of this dissertation was to develop computational tools and experimental techniques to assess key variables that affect algal growth and productivity, and to improve microalgal cultivation in ORPs. The effects of major parameters on growth, were investigated and the optimum C. vulgaris growth condition was determined at 52 W/m2, 24&deg;C, and pH of 7.4, using Response Surface Methodology. The C. vulgaris grown in swine wastewater with 102 mg/L nitrogen and 76 mg/L phosphorus at the optimum environmental condition achieved the average growth rate of 0.16 g/L/day, compared to 0.19 g/L/day for its growth in the modified Bold's medium with 100 mg/L nitrogen and 53 mg/L phosphorus, at the same condition. Results indicated that at NC weather conditions, C. vulgaris grown in swine wastewater in a pond with 0.3 m medium depth, can reach a biomass and lipid productivity of 80 and 20 tons/hectare/year, respectively, at the harvesting cell density of 0.1 g/L. However, the algal productivity decreased significantly with the increase of harvesting cell density. A specific growth rate model of C. vulgaris was generated as a function of light intensity, temperature and pH. A Computational Fluid Dynamics (CFD) model was developed to simulate the multiphase flow in ORPs to investigate the effects of operational conditions on biomass concentration and light intensity distribution. Operating large scale ORPs at 0.2 m/s inlet velocity resulted in a significant decrease in dead zone areas in comparison with 0.1 m/s. However, further increase in velocity to 0.3 m/s did not make significant changes. CFD models were then integrated with the growth kinetic model to simulate the dynamic growth of C. vulgaris in ORPs. The predicted algal growth and productivity well agreed with those measured values. The predicted average algal productivities for the 3-week cultivation of C. vulgaris in the lab-scale ORPs were 7.34, 7.4, and 7.46 g/m2/day for medium depths of 0.20, 0.25, and 0.30 m, respectively, which well agreed with the measured values of 6.78, 7.23 and 7.39 g/ m2/day for medium depths 0.20, 0.25, and 0.30 m, respectively. Simulations were conducted to study different harvesting methods. The average algal productivity for the 3-week cultivation in the ORP with 0.2 m depth by harvesting 50% algae at the target 0.2 g/L cell density was 10.5 g/m2/day, which was 54.7% higher than 6.78 g/ m2/day for the 3-week cultivation under the same condition without harvesting. The average algal productivity decreased with the increase of harvesting cell density.</p>
69

Biological hydrogen production using an anaerobic fluidised bed bioreactor

Thompson, Liam Jed 16 November 2006 (has links)
Faculty of Science School of Molecular and Cell Biology 9904041r lthompson@csir.co.za / The production of H2 was monitored using an automated, semi-continuously fed anaerobic fluidised bed bioreactor containing 2 facultatively anaerobic bacteria, Enterobacter cloacae (E. cloacae Ecl) and Citrobacter freundii (C. freundii Cf1). Shake flask tests using Endo formulation with modified C:N:P ratios, showed that a 334:28:5.6 ratio gave the highest attached counts of E. cloacae Ecl and C. freundii Cf1 in both single and binary species biofilms grown on granular activated carbon. Once the reactor had achieved steady state after 30 days using the modified C:N:P ratio, pH, redox potential, temperature, volatile fatty acids and the H2 production rate were monitored. The H2 production rate of 95 mmol H2 / (l x h) compared favourably with previous studies. Bacterial biofilms counts for both E. cloacae Ecl and C. freundii Cf1 remained high around 9.0 log cfu/g granular activated carbon, although biomass overgrowth could not be controlled in the reactor. The efficiency of converting sucrose into H2 was calculated at 20.5%. Therefore use of this technology to power a 5.0kW proton exchange fuel cell for a single rural household is currently not feasible due to the high organic load required. Pooling of wastewater generation capacity, improvement of bacterial strain selection and feed formulation, pH control, gas removal and purification are factors that need to be considered for future improvement of conversion efficiencies. Use of this technology would be most suited for industrial processes generating large volumes of wastewater high in carbohydrates. Alternatively, municipal wastewater treatment facilities could be converted into electricity generating facilities through the combination of this technology and proton exchange membrane fuel cells.
70

O uso do carvão vegetal nos Pólos Guseiros: implicações sociais, ambientais e econômicas / The use of charcoal pig iron at the Poles: social, environmental and economic

Luczynski, Estanislau 25 August 1995 (has links)
Este trabalho aborda diversas implicações de ordem tecnológica, ambiental e social relacionados ao uso de carvão vegetal nos pólos guseiros. Através de coleta de dados em publicações técnicas, visitas a centros de tecnologia guseira e entrevistas com especialistas da área, foram levantadas as informações que serviram de base à elaboração deste trabalho. A análise e interpretação dos resultados obtidos mostram que a manutenção da produção de ferro-gusa depende do contínuo fornecimento de carvão vegetal, como termo-redutor de boa capacidade calorífica, preço baixo e fácil acesso. Todavia, nas condições atuais, o suprimento de carvão vegetal à indústria está relacionado à exploração intensiva de florestas nativas e uma correspondente falta de áreas reflorestadas capazes de suprir a demanda de lenha para carvoejamento. Além do carvão vegetal, outros insumos também podem ser usados na redução do minério de ferro: o gás natural (na produção integrada de aço) o carvão de coco de babaçu, o carvão vegetal de espécies nativas da Amazônia e mesmo o carvão mineral. Estes insumos, entretanto, apresentam problemas ainda não totalmente quantificados, como suprimento, tecnologia adequada de uso e custos de exploração. O uso intensivo de carvão vegetal se baseia na existência de uma rede de carvoejadores e fornos, que operam num ritmo de trabalho intenso (às vezes cerca de quinze horas por dia), baixa remuneração por madeira carvoejada (meio dólar por metro cúbico de carvão vegetal) e falta de seguridade social. De modo geral, os produtos de gusa pouco consideram o uso de carvão de florestas plantadas, pois admitem que um carvão de maior custo, constituir-se-ia em ameaça à própria continuação da produção de ferro-gusa. / The aim of this work is to discuss implications technological, environmentally and social limitations of the pig-iron´s production using charcoal. Through technical papers, technical visits to research centers and interview with experts, a data basis was collected to produce this work. The analysis of data showed that: the continuity of pig-iron making depends on continuos supply of charcoal, at low cost, with good heat capacity, and with easy acess. However, under current conditions, the charcoal supply to industry is depending of a intensive exploration of native forest. At the same time, there is a lack of land suitablefor reforestation to provide wood to renewable charcoal making. Nevertheless, there are several resources that can be used to reduce the iron ore: charcoal of babassu coconut, charcoal of native amazonic trees, natural gas (integrated plants) and even coal. Some of them are candidates to replace the charcoal, but further technological, infrastructural and economic developments are still required. The intensive utilization of charcoal by siderurgy is based in a network of kilns and charcoal makers working under extreme conditions (indeed, some work fifteen hours per day), they have no social security and extremely low wages (some receive only half a dollar per cubic metre of charcoal). In general, pig-iron´s makers do not consider the use of charcoal from forested wood, because its higher cost may challenge the viability of pig-iron production.

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