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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.
21

Elucidating the solid, liquid and gaseous products from batch pyrolysis of cotton-gin trash.

Aquino, Froilan Ludana 15 May 2009 (has links)
Cotton-gin trash (CGT) was pyrolyzed at different temperatures and reaction times using an externally-heated batch reactor. The average yields of output products (solid/char, liquid/bio-oil, and gaseous) were determined. The heating value (HV) of CGT was measured to be around 15-16 MJ kg- 1 (6500-7000 Btu lb-1). In the first set of tests, CGT was pyrolyzed at 600, 700, and 800°C and at 30, 45, and 60 min reaction period. The maximum char yield of 40% by weight (wt.%) was determined at 600°C and 30 min settings, however, the HV of char was low and almost similar to the HV of CGT. A maximum gas yield of 40 wt.% was measured at 800°C and 60 min and the highest liquid yield of 30 wt.% was determined at 800°C and 30 min. In the modified pyrolysis test, the effects of temperature (500, 600, 700, and 800°C) on the product yield and other properties were investigated. The experiment was performed using the same reactor purged with nitrogen at a rate of 1000 cm3 min-1. Gas yield increased as temperature was increased while the effect was opposite on char yield. The maximum char yield of 38 wt.% was determined at 500°C and 30 min. The char had the largest fraction in the energy output (70-83%) followed by gas (10-20%) and bio-oil (7- 9%). Maximum gas yield of 35 wt.% was determined at 800°C. The average yield of CO, H2 and total hydrocarbons (THC) generally increased with increased temperature but CO2 production decreased. Methane, ethane, and propane dominated the THC. The bio-oil yield at 600°C was the highest at about 30 wt.% among the temperature settings. The HV of bio-oil was low (2-5 MJ kg-1) due to minimal non-HC compounds and high moisture content (MC). A simple energy balance of the process was performed. The process was considered energy intensive due to the high amount of energy input (6100 kJ) while generating a maximum energy output of only 10%. After disregarding the energy used for preparation and pyrolysis, the energy losses ranged from 30-46% while the energy of the output represent between 55-70% of the input energy from CGT.
22

Residual Visions: Rubbish, Refuse and Marginalia in Italian Cinema from Neorealism to the Present

Muri-Rosenthal, Adam January 2013 (has links)
While the themes of garbage and refuse pervade many of the most important works of Italian cinema from the era of Neorealism to the present, thus far no scholarly attempts have been made to examine the commonalities germane to their portrayal and their relationship to larger questions of Italian cultural trends. The present study explores how filmmakers' depiction of the residual is synecdochic of an artistic vision that endeavors to capture reality at its most unprepared and, subsequently, comes to represent the increasing complexity of the mimetic undertaking in an Italian society thrust rapidly into the late stages of capitalism. / Romance Languages and Literatures
23

The Painter's Wife and Other Stories

Nadon, Candace 05 April 2013 (has links)
The Painter’s Wife and Other Stories is a novella and a collection of short fiction focusing on the lives of women and men in the contemporary Western United States. In their exploration of Western life, the novella and short stories subvert the popular mythology of the West. The novella and stories are set in one of three Colorado settings: the city of Denver, the rural Western slope, and the mountain communities of the Western Slope. Beyond being linked by region, the stories are also loosely linked by characters. Characters from one story are mentioned or make brief appearances in others, reinforcing the idea of a people connected by community and landscape.
24

Cyclone Performance for Reducing Biochar Concentrations in Syngas

Saucier, David Shane 16 December 2013 (has links)
Cotton gins have a readily available supply of biomass that is a by-product of cotton ginning. A 40 bph - cotton gin processing stripped cotton must manage 2,600 to 20,000 tonnes of cotton gin trash (CGT) annually. CGT contains approximately 16.3 MJ/kg (7000 Btu/lb.). CGT has the potential to serve as a renewable energy source. Gasification of biomasses such as CGT can offer processing facilities the opportunity to transform their waste biomass into electricity. The gasification of CGT yields 80% synthesis gas (syngas) and 20% biochar. The concentration of biochar in the syngas needs to be reduced prior to the direct fueling of an internal combustion engine driving a generator for electricity production. It was estimated that direct fueling of an internal combustion engine with syngas to drive the generator to produce electricity would cost $1M per megawatt (MW). In contrast, a 1MW system that consists of a boiler and steam turbine would cost $2M/MW. The current provisional patent for the TAMU fluidized bed gasification (FBG) unit uses a 1D2D and 1D3D cyclone for the removal of biochar. A cyclone test stand was designed and constructed to evaluate cyclone capture efficiencies of biochar. A statistical experiment design was used to evaluate cyclone performances for varying concentrations of biochar. A total of 24 tests for the 1D2D and 36 tests for the 1D3D cyclone were conducted at ambient conditions. Average collection efficiency for the 1D2D cyclone was 96.6% and 96.9% for the 1D3D cyclone. An analysis on the cyclone’s pressure drop was performed to compare the change in pressure drop from air only passing through the cyclone and when the cyclones are loaded with biochar. The average change in pressure drop for the 1D2D cyclone was a decrease of 74%, and the average change in pressure drop for the 1D3D cyclone was a decrease of 36%. An economic feasibility study was conducted to determine the price per kWh to produce electricity for a CGT fueled internal combustion engine power plant (ICPP) and a boiler and steam turbine power plant (SPP). The simulated cotton gin is a 40 bph rated facility operating for 2,000 hours a season (200% utilization) processing stripped cotton that yields approximately 180 kg/bale (400 lbs/bale) of CGT. Revenues consist of the electricity and natural gas expenses incurred during the ginning season, along with the extra electricity produced and sold back to the utility company at the whole price. Loan payments and operating costs include labor, maintenance, taxes, and insurance. Labor costs, the selling price of electricity and biochar are varied in the economic model. The ICPP has a NPV of $1,480,000, and the SPP has a NPV of -$160,000, under the base assumptions. The sensitivity analysis resulted in the selling price of electricity as having the largest change on the NPV for both of the power plants. The average predicted purchase price of electricity is $0.10/kWh for the twenty year simulation. The average price to produce electricity, with no source of revenue generation for the ICPP is $0.20/kWh and $0.26/kWh for the SPP.
25

Cotton Leaf Grade as Influenced by Harvest Aid Regimes and Cultivar Characteristics

Eder, Zachary Phillip 16 December 2013 (has links)
Cotton, Gossypium hirsutum L., leaf grade values can significantly increase with remnants of leaf and bract materials, and can result in increased ginning costs and discounts to the producer. Cotton classed through the USDA-AMS Classing Office in Corpus Christi, Texas has reported increases in leaf grade values beginning in 2000 (USDA, 2012). The impacts of the interaction of agronomic characteristics of cotton cultivars with those of various harvest aid regimes were studied over three growing seasons, and data were used to narrow possible contributors to the observed increased leaf grade values. Multiple trials were conducted throughout the Coastal Bend and Blackland Prairie of Texas, in addition to Tifton, Georgia. Cotton was harvested, lint samples were ginned in a microgin, and lint quality was quantified with HVI. Harvest aid regimes selected provided a broad range of defoliation and desiccation, from a multiple herbicidal and hormonal modes-of-action. Defoliation levels ranged from 0 to 96% and desiccation levels ranged from 0 to 90%. Harvest aid treatments had no impact (P≤0.05) on leaf grade values for either of the years of the trials. Multiple trials were conducted in five counties in Texas, including the Lower and Upper Coastal Bend and the Blackland Prairie, and were defoliated with a uniform harvest aid treatment to identify leaf and bract morphological differences, and to determine their role in leaf grade. Multi-acre module trials were conducted with a smooth leaf cultivar and a hairy leaf cultivar to obtain leaf grade values following commercial ginning. Leaf and bract pubescence, and leaf and bract area were collected to analyze the resulting impact on cotton leaf grade values. Visual quantification of leaf and bract trichome density was quantified on 10 youngest fully-expanded leaves and 10 mid-canopy full sized bolls, respectively, when cotton was at physiological cut-out. Trichome density quantification indicated substantial variation in cultivars and discrepancies from company based rating systems. Leaf grades values generally increased with increasing trichomes densities, although not always statistically significant. In the split plot cultivar and harvest aid trial, harvest aid efficacy was similar for each of the cultivars, but cultivar trichome density was positively influence the cotton leaf grade value.
26

A comparison of the effectiveness of four unmanned interpretive techniques in a park setting

Stolarz, Thomas J. January 1984 (has links)
The purpose of this study was to investigate the difference in effectiveness of four unmanned interpretive devices, which were: 1) a visual shock display, 2) a written brochure, 3) written signs, and 4) an automated audiovisual presentation. These technique types have only been sparsely studied in the past with regard to their comparative efficacy. Examination of the differences in relative effectiveness was warranted to help establish guidelines for future interpretive technique design and utilization.The four techniques, along with a control, were compared two at a time using aluminum can litter/recycling as the concept being interpreted. The number of aluminum cans recovered from park trash containers during each treatment period was used to evaluate the techniques. The comparison between each set of techniques was made using a z-statistic for a large sample, normal population. The number of cans purchased prior to park visitation was also analyzed with this same statistic to determine if this outside factor had any influence on the data.Of the four unmanned interpretive techniques tested, the written sign and the visual shock display were significantly more effective at interpreting the concept than were the written brochure, automated audiovisual program or the control. The written sign and the visual shock display were equally effective, while the automated audiovisual program and the written brochure were not significantly more effective than a control. Cans purchased prior to park visitation had no detectable effect on these results. Also, rainfall and temperature patterns showed no correlation with the data.
27

PRESSURISED ENTRAINED FLOW GASIFICATION OF SUGAR CANE WASTES FOR COGENERATION.

Joyce, James Alexander Unknown Date (has links)
This work has examined the thermochemical conversion of sugar cane processing wastes (bagasse and cane harvesting trash) for use in the design of pressurised entrained flow gasification power cycles (~20 Barg, 600-900oC). The two key parameters of interest were the residual char yield from initial pyrolysis and the heterogeneous reactivity of the char with respect to carbon dioxide. Char yield and gasification rates were measured by a conventional wire mesh reactor and thermogravimetric (TGA) technique, an in-situ sample charring TGA technique and with an entrained flow reactor specifically designed for this work. The new experimental reactor concept is one of the major contributions of the work. Chars from the entrained flow experiments were characterised by optical microscope, SEM/EDS, TEM/EDS and XPS techniques, to help elucidate the processes occurring during pyrolysis and gasification. The key findings and conclusions of the work were as follows: 1. Initial (pyrolysis) char yields were consistent with the data reported in literature for similar materials. Char yields varied with reaction conditions, from 6 to 49 wt% daf for cane trash and 4 to 40 wt% daf for bagasse. Ash content also had a significant effect on char yield. The char yield for both cane trash and bagasse increased in proportion to the logarithm of system pressure. 2. A relatively simple empirical model for char yield under pressurised entrained flow conditions was formulated. This could predict char yields for both the experimental data in this work and those reported in literature for similar biomass materials. While temperature, pressure and ash content were all significant parameters in the model, the primary fitting parameter was a measure of the contribution of secondary char forming reactions and ongoing pyrolysis to char yield. The identification of this parameter is one of the contributions of this work. 3. The measured initial rate of char gasification by carbon dioxide was 0.06 to 1.2 mg per gram of initial char, over the temperature range 750 to 900oC. The rate of gasification was so low as to not contribute significantly to overall fuel conversion in the reaction residence times iv expected of a commercial gasifier. In essence almost all of the experimentally measured fuel conversion could be attributed to pyrolysis, which resulted in 85-95% fuel conversion. 4. Both the raw materials and the residual chars had low surface areas and negligible microporosity. The majority of the measured surface area may have been associated with the ash component rather than the carbonaceous component, which supported the finding of low reactivity. 5. The silica component of the chars exhibited crystalline silicate formation by migration of metal species over time periods of minutes. These silicates displayed signs of sintering, but otherwise remained physically intact; leaving a characteristic skeleton that corresponded to the original structure in the raw materials. 6. The gasification rate showed a time dependent decrease in the entrained flow experiments. This was attributed to coke formation on the char surface, followed by carbon trapping in the ash component at high levels of conversion. Both findings are significant contributions from this work, because they highlight key mechanisms that hinder fuel conversion in the proposed gasification concept. The broad coverage achieved in this work has provided an overall picture of how fuel conversion progresses during the pressurised entrained flow gasification of sugar cane wastes. It is recommended that many of the aspects highlighted in this work be examined further, to confirm the findings and to investigate the means to avoid the factors identified in this work as hindering fuel conversion.
28

Piranha: An Autonomous Water Surface Robot.

Liu, Xiahua January 2021 (has links)
No description available.
29

One in the Head: A White Trash Memoir

Branscum, John 30 September 2010 (has links)
No description available.
30

Visitor perceptions and awareness of litter at the Johannesburg Zoo

Malepa, Piet Lesiba 05 1900 (has links)
The aim of the study was to determine how litter affects the image of the environment and the animals at the Johannesburg Zoo, situated in the Northern part of Johannesburg, as perceived by various stakeholders. Furthermore, effectiveness of the educational awareness programmes developed and currently being presented at the Zoo were assessed. The central themes of the research on the issue of litter in a conservation area included the current status of litter in the Johannesburg Zoo, the perception of stakeholders frequenting or living in the vicinity of the Zoo and the nature and effectiveness of educational programmes presented at the Zoo. The stakeholders included visitors (n=332), employees (n=20) and others who represented the Zoo and people from the neighbouring Forest Town. It was possible to collect data on the premises while the Zoo was in full operation. The data-collection tools included two questionnaires (for visitors and employees) and interviews (other stakeholders), as well as a reflective recall of eight years of hands-on experiences and observations of a current curator at the Zoo. The latter served as a situation analysis of the Zoo to provide a backdrop for exploring the litter problem and served as background for designing the data-collection tools. The data of the survey conducted with questionnaires was quantitative in nature and was analysed descriptively in form of frequencies and percentages. The qualitative data gathered by means of the interviews were analysed and described against the experiences, beliefs and contact with the Zoo of the specific stakeholder. The educational programmes were described and the content assessed based on the effectiveness regarding litter minimisation information. The situation analysis revealed some tragic consequences of littering at the Zoo. It became clear that educating the public was a necessity to provide knowledge in such a way that it would inculcate a spirit of caring about and valuing the environment and the animals. All stakeholders identified that the Zoo has a serious litter problem and that the signboards needed more specific litter control messages and should be placed strategically so that they are noticed. Although the number of dustbins were sufficient, their distribution and placement in and around the Zoo were not effective. Educational programmes were considered by all to be the answer to the litter problem if the content could be expanded to include information on the consequences of and the legislation on littering. Recommendations regarding litter management for Johannesburg Zoo and for further investigation were suggested. / Geography / M. Sc. (Geography)

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