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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.
961

Biofilm Reduction of Oxidized Contaminants

January 2012 (has links)
abstract: The overall goal of this dissertation is to advance understanding of biofilm reduction of oxidized contaminants in water and wastewater. Chapter 1 introduces the fundamentals of biological reduction of three oxidized contaminants (nitrate, perchlorate, and trichloriethene (TCE)) using two biofilm processes (hydrogen-based membrane biofilm reactors (MBfR) and packed-bed heterotrophic reactors (PBHR)), and it identifies the research objectives. Chapters 2 through 6 focus on nitrate removal using the MBfR and PBHR, while chapters 7 through 10 investigate simultaneous reduction of nitrate and another oxidized compound (perchlorate, sulfate, or TCE) in the MBfR. Chapter 11 summarizes the major findings of this research. Chapters 2 and 3 demonstrate nitrate removal in a groundwater and identify the maximum nitrate loadings using a pilot-scale MBfR and a pilot-scale PBHR, respectively. Chapter 4 compares the MBfR and the PBHR for denitrification of the same nitrate-contaminated groundwater. The comparison includes the maximum nitrate loading, the effluent water quality of the denitrification reactors, and the impact of post-treatment on water quality. Chapter 5 theoretically and experimentally demonstrates that the nitrate biomass-carrier surface loading, rather than the traditionally used empty bed contact time or nitrate volumetric loading, is the primary design parameter for heterotrophic denitrification. Chapter 6 constructs a pH-control model to predict pH, alkalinity, and precipitation potential in heterotrophic or hydrogen-based autotrophic denitrification reactors. Chapter 7 develops and uses steady-state permeation tests and a mathematical model to determine the hydrogen-permeation coefficients of three fibers commonly used in the MBfR. The coefficients are then used as inputs for the three models in Chapters 8-10. Chapter 8 develops a multispecies biofilm model for simultaneous reduction of nitrate and perchlorate in the MBfR. The model quantitatively and systematically explains how operating conditions affect nitrate and perchlorate reduction and biomass distribution via four mechanisms. Chapter 9 modifies the nitrate and perchlorate model into a nitrate and sulfate model and uses it to identify operating conditions corresponding to onset of sulfate reduction. Chapter 10 modifies the nitrate and perchlorate model into a nitrate and TCE model and uses it to investigate how operating conditions affect TCE reduction and accumulation of TCE reduction intermediates. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2012
962

Analysis of Life Cycle Costs and Energy Savings of Electrochromic Glazing for an Office Building

January 2012 (has links)
abstract: Building Envelope includes walls, roofs and openings, which react to the outdoor environmental condition. Today, with the increasing use of glass in building envelope, the energy usage of the buildings is increasing, especially in the offices and commercial buildings. Use of right glass type and control triggers helps to optimize the energy use, by tradeoff between optical and thermal properties. The part of the research looks at the different control triggers and its range that governs the use of electrochromic glass to regulate the energy usage in building. All different control trigger that can be possibly used for regulating the clear and tint state of glass were analyzed with most appropriate range. Its range was triggered such that 80% time of the glass is trigger between the ranges. The other building parameters like window wall ratio and orientations were also investigated. The other half of the research study looks into the feasibility of using the Electrochromic windows, as it is ought to be the main factor governing the market usage of Electrochromic windows and to investigate the possible ways to make it feasible. Different LCC parameters were studied to make it market feasible product. This study shows that installing this technology with most appropriate trigger range can reduce annual building energy consumption from 6-8% but still cost of the technology is 3 times the ASHRAE glass, which results in 70-90 years of payback. This study concludes that south orientation saves up to 3-5% of energy and 4-6% of cooling tons while north orientation gives negligible saving using EC glass. LCC parameters show that there is relative change in increasing the net saving for different parameters but none except 50% of the present glass cost is the possible option where significant change is observed. / Dissertation/Thesis / M.S.D. Architecture 2012
963

Associative Design for Building Envelopes' Sun Control and Shading Devices

January 2012 (has links)
abstract: In geographical locations with hot-arid climates, sun control in buildings is one primary problem to solve for the building envelope design. Today's technological advances in building science bring with them the opportunity to design dynamic façade systems for sun radiation control and daylighting. Although dynamic systems can become an attractive visual element, they can be costly and challenging to maintain for building owners. Alternatively, fixed solar-shading systems can be designed to create dynamism in the façade of the building, while providing similar functionalities for sun control. The work presented in this project focuses on the use of a visual scripting editor for modeling software, Grasshopper, to develop a Solar Control Visual Script that evaluates building envelope surfaces with planar and non-uniform rational basis-spline (NURBS) forms and provides projections for fixed sun control systems. The design platform of Grasshopper allows individuals with no experience or prior computer coding education to build up programming-like capabilities; this feature permits users to discover new design possibilities within flexible frames that can contribute to the overall design being pursued, while also having an environmental response. The Solar Control Visual Script provides minimum sizing geometries that achieve shading in openings at a particular date and time of the year. The model for this method of analysis makes use of three components to derive the appropriate values for the projections of shading geometries: typical meteorological year (TMY) data, irradiation isotropic equations and shading profile angles equations for vertical and tilted surfaces. Providing an automatic visual of generated geometries uncovers the opportunity to test several model forms and reiterates the analysis when modifying control parameters. By employing building science as a set of environmental parameters, the design outcome bears a dynamic form that responds to natural force conditions. The optimized results promote an efficient environmental design solution for sun control as an integral alternative into the building envelope. / Dissertation/Thesis / M.S. Built Environment 2012
964

Handling Solid and Hazardous Waste by Waste Pickers: A Case Study of Phnom Penh, Cambodia

January 2012 (has links)
abstract: The handling of waste encompasses the following processes: recycling, collection, treatment, and disposal. It is crucial to provide a cost-effective waste management system that improves public health and reduces environmental risks. In developing countries, proper handling of solid and hazardous wastes remain severely limited in urban cities if the industries and hospitals producing it do not take responsibility. Recycling and reusing of 12% of total waste in Phnom Penh is an active industry in Cambodia, driven by an informal network of waste pickers, collectors, and buyers. This thesis examines the environmental situation of solid and hazardous wastes in Phnom Penh. The socio-economic background of waste pickers and their current practices for handling solid and hazardous wastes will be mainly discussed in order to understand health and sanitation impacts and risks for disposal of solid and hazardous waste by these informal waste pickers. Surveys and interviews with the following sources are conducted: waste pickers, community members, observation at local dumpsites, governmental officials, and other non-government organization agencies in Phnom Penh, Cambodia. This thesis reports the external and internal factors that hinder safety and cost-effective management for disposal of solid and hazardous wastes. Multiple literature reviews are assessed in regards to the health effects, economic, and social impacts in developing countries. Evidentially, after attending several training and environmental awareness-raising programs, waste pickers expressed concerns about their health and the environment. Instead of receiving support, waste pickers are under economic pressure to use improper tools for waste picking, to stop working, get access to health care/service, to change their career, and prevent contact to limit serious communicable diseases and disability. As a result, the government and other related government agencies have made an effort to establish sanitation handling, treatment, and disposal systems by closing the old dumpsite. Due to limited entrepreneurship and business experience after training, most waste pickers cannot initiate micro business or find new jobs and then resume their waste picking. In conclusion, this thesis proposed that there are alternative technologies and management methods that will allow waste pickers to maintain employment while minimizing hazardous waste. Some examples of alternatives for waste pickers are establishing a material recovery center and alternative higher income occupation. / Dissertation/Thesis / M.S.Tech Human and Social Dimensions of Science and Technology 2012
965

Environmental Values, Objectivity, and Advocacy: A Sociological Study of Academic Environmental Scientists

January 2012 (has links)
abstract: Professional environmental scientists are increasingly under pressure to inform and even shape policy. Scientists engage policy effectively when they act within the bounds of objectivity, credibility, and authority, yet significant portions of the scientific community condemn such acts as advocacy. They argue that it is nonobjective, that it risks damaging the credibility of science, and that it is an abuse of authority. This means objectivity, credibility, and authority deserve direct attention before the policy advocacy quagmire can be reasonably understood. I investigate the meaning of objectivity in science and that necessarily brings the roles of values in science into question. This thesis is a sociological study of the roles environmental values play in the decisions of environmental scientists working in the institution of academia. I argue that the gridlocked nature of the environmental policy advocacy debates can be traced to what seems to be a deep tension and perhaps confusion among these scientists. I provide empirical evidence of this tension and confusion through the use of in depth semi-structured interviews among a sampling of academic environmental scientists (AES). I show that there is a struggle for these AES to reconcile their support for environmentalist values and goals with their commitment to scientific objectivity and their concerns about being credible scientists in the academy. Additionally, I supplemented my data collection with environmental sociology and history, plus philosophy and sociology of science literatures. With this, I developed a system for understanding values in science (of which environmental values are a subset) with respect to the limits of my sample and study. This examination of respondent behavior provides support that it is possible for AES to act on their environmental values without compromising their objectivity, credibility, and authority. These scientists were not likely to practice this in conversations with colleagues and policy-makers, but were likely to behave this way with students. The legitimate extension of this behavior is a viable route for continuing to integrate the human and social dimensions of environmental science into its practice, its training, and its relationship with policy. / Dissertation/Thesis / M.S. Environmental Social Science 2012
966

An examination of vegetation modeling-related issues and the variation and climate sensitivity of vegetation and hydrology in China

Tang, Guoping 09 1900 (has links)
xvi, 156 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / This dissertation examined a number of general vegetation-modeling issues, and the sensitivity of terrestrial net primary productivity (NPP), soil moisture and actual evapotranspiration (ET) to climatic variations in China. The specific issues addressed included: (1) the sensitivity of the performance of an equilibrium vegetation model to the choice of monthly-mean climatologies, observed validation data sets, and three map-comparison approaches; and (2) the limitations of existing map-comparison approaches in vegetation modeling; and the variation and climate sensitivity of (3) terrestrial NPP and (4) soil moisture and actual ET in China. To address the first issue, BIOME4 (Kaplan et al., 2002), a typical example of an equilibrium vegetation model, was used along with a set of 19 different monthly-mean climatologies, three validation data sets, and several map-comparison methods. To address the second issue, the "opposite and identity" (01) index (Tang, 2008) was developed for evaluating the correspondence of two simulation results. To examine the third issue, a set of historical NPP dynamics were derived from normalized-difference vegetation index data by modifying the CASA (Potter et al., 1999) approach and then were linked to the variation of temperature and precipitation to analyze the climatic effects on terrestrial NPP in China. To examine the fourth issue, a stand-alone water balance model, LH (LPJ-hydrology), was developed by modifying the LPJ dynamic global vegetation model (Sitch et al., 2003), and applying it to a China case study. The results of these analyses indicate that (1) the 30-year mean-climatology preceding the observed data produces the most accurate vegetation simulations; (2) the OI index is a useful tool to compare two simulation results or to evaluate simulation results against observed spatiotemporal data; (3) climate and land-use change jointly controlled NPP dynamics in the eastern monsoon zone of China. In contrast, NPP dynamics in the north-west and zone and in the Tibet Plateau frigid zone depended more on climatic variation; and (4) the spatial patterns of soil moisture and ET in China were correlated with the variation of temperature and precipitation. However, the strength of such relationship varies spatially. This dissertation includes my published and coauthored materials. / Adviser: Patrick J. Bartlein
967

The geomorphic legacy of splash dams in the Southern Oregon Coast Range

Phelps, Jessica D., 1985- 03 1900 (has links)
xi, 38 p. : ill. (some col.), maps / Splash dams were in-stream structures that were used to facilitate log driving in the Oregon Coast Range (OCR) between 1880 and 1957. This study explores the potential legacy impacts of "splashing" on stream morphology in Camp Creek and the West Fork Millicoma in the Southern OCR. Field data on stream morphology, GIS analysis, and hydraulic modeling were used in a paired-reach and paired-basin approach to determine legacy impacts on stream widths, depths, cross-sectional shapes, wood accumulation and sediment size. The paired-reach approach did not demonstrate significant differences up- or downstream of past dam locations. The paired-basin approach indicates that "splashing" is associated with narrower streams and less fine sediment, although it is not clear whether this difference reflects legacy impacts of splash dams or other factors driving variations between basins. Splash dam releases significantly exceeded 100-yr flood magnitudes in headwater regions and were comparable to 100-yr flows in lower reaches. / Committee in charge: W. Andrew Marcus, Chairperson; Patricia McDowell, Member
968

Profitability and Environmental Benefit of Providing Renewable Energy for Electric Vehicle Charging

January 2014 (has links)
abstract: This study evaluates the potential profitability and environmental benefit available by providing renewable energy from solar- or wind-generated sources to electric vehicle drivers at public charging stations, also known as electric vehicle service equipment (EVSE), in the U.S. Past studies have shown above-average interest in renewable energy by drivers of plug-in electric vehicles (PEVs), though no study has evaluated the profitability and environmental benefit of selling renewable energy to PEV drivers at public EVSE. Through an online survey of 203 U.S.-wide PEV owners and lessees, information was collected on (1) current PEV and EVSE usage, (2) potential willingness to pay (WTP) for upgrading their charge event to renewable energy, and (3) usage of public EVSE if renewable energy was offered. The choice experiment survey method was used to avoid bias known to occur when directly asking for WTP. Sixty percent of the participants purchased their PEVs due to environmental concerns. The survey results indicate a 506% increase in the usage of public pay-per-use EVSE if renewable energy was offered and a mean WTP to upgrade to renewable energy of $0.61 per hour for alternating current (AC) Level 2 EVSE and $1.82 for Direct Current (DC) Fast Chargers (DCFC). Based on data from the 2013 second quarter (2Q) report of The EV Project, which uses the Blink public EVSE network, this usage translates directly to an annual gross income increase of 668% from the original $1.45 million to $11.1 million. Blink would see an annual cost of $16,005 per year for the acquisition of the required renewable energy as renewable energy credits (RECs). Excluding any profit seen purely from the raise in usage, $3.8 million in profits would be gained directly from the sale of renewable energy. Relative to a gasoline-powered internal combustion engine passenger vehicle, greenhouse gas (GHG) emissions are 42% less for the U.S. average blend grid electricity-powered electric vehicle and 99.997% less when wind energy is used. Powering all Blink network charge events with wind energy would reduce the annualized 2Q 2013 GHG emissions of 1,589 metric tons CO2 / yr to 125 kg CO2 / yr, which is the equivalent of removing 334 average U.S. gasoline passenger cars from the road. At the increased usage, 8,031 metric tons CO2 / yr would be prevented per year or the equivalent of the elimination of 1,691 average U.S. passenger cars. These economic and environmental benefits will increase as PEV ownership increases over time. / Dissertation/Thesis / Masters Thesis Technology 2014
969

Photo-chemical and Microbial Degradation of Dissolved Organic Carbon in the Colorado River System

January 2015 (has links)
abstract: The focus of this thesis is to study dissolved organic carbon composition and reactivity along the Colorado and Green Rivers. Dissolved organic carbon (DOC) in large-scale, managed rivers is relatively poorly studied as most literature has focused on pristine unmanaged rivers. The Colorado River System is the 7th largest in the North America; there are seventeen large dams along the Colorado and Green River. DOC in rivers and in the lakes formed by dams (reservoirs) undergo photo-chemical and bio-degradation. DOC concentration and composition in these systems were investigated using bulk concentration, optical properties, and fluorescence spectroscopy. The riverine DOC concentration decreased from upstream to downstream but there was no change in the specific ultraviolet absorbance at 254 nm (SUVA254). Total fluorescence also decreased along the river. In general, the fluorescence index (FI) increased slightly, the humification index (HIX) decreased, and the freshness index (β/α) increased from upstream to downstream. Photo-oxidation and biodegradation experiments were used to determine if the observed changes in DOC composition along the river could be driven by these biogeochemical alteration processes. In two-week natural sunlight photo-oxidation experiments the DOC concentration did not change, while the SUVA254 and TF decreased. In addition, the FI and ‘freshness’ increased and HIX decreased during photo-oxidation. Photo-oxidation can explain the upstream to downstream trends for TF, FI, HIX, and freshness observed in river water. Serial photo-oxidation and biodegradation experiments were performed on water collected from three sites along the Colorado River. Bulk DOC concentration in all samples decreased during the biodegradation portion of the study, but DOC bioavailability was lower in samples that were photo-oxidized prior to the bioavailability study. The upstream to downstream trends in DOC concentration and composition along the river can be explained by a combination of photo-chemical and microbial degradation. The bulk DOC concentration change is primarily driven by microbial degradation, while the changes in the composition of the fluorescent DOC are driven by photo-oxidation. / Dissertation/Thesis / Masters Thesis Chemistry 2015
970

Gardens of Justice: Food-Based Social Movements in Underserved, Minority Communities

January 2015 (has links)
abstract: Residents of the United States increasingly support organic and local food systems. New Social Movement theorists have described alternative agriculture as a social movement that transcends social class. Other scholars have critiqued alternative agriculture for catering to a middle-class, white public. Simultaneously, geographers have identified communities across the United States that struggle with reduced access to healthy fruits and vegetables. In some of these neighborhoods, known as “food deserts,” local groups are redefining an inequitable distribution of healthy food as a social injustice, and they have begun initiatives to practice “food justice.” The overarching research questions of this study are: 1) How do communities become food deserts? 2) How do food justice movements crystallize and communities practice food justice? 3) What are the social outcomes of food justice movements? Using an Ecology of Actors framework, this study analyzes the actors and operational scales of three food justice movements in Phoenix, Arizona. A narrative analysis of historical scholarly materials and other artifacts reveals that, for more than a century, some communities have tried to create minority-operated local food systems. However, they were thwarted by racist policies and market penetration of the conventional US food system. Interviews with residents, garden organizers and food justice advocates living and working in the city create a narrative of the present day struggle for food justice. Results of this work show that contemporary residents describe their foodscape as one of struggle, and carless residents rely upon social networks to access healthy food. Garden organizers and gardeners are creating networks of community gardens, market gardens, and informal farmers’ markets. They are actively transforming their communities’ landscapes with sophisticated garden ecology in an intense urban heat island. However, the movement’s continued success may be threatened. Many new Phoenix-based local food coalitions and national alternative agriculture social movements are now working to alter Phoenix’s foodscape. Composed of well-educated professionals, who have adopted a justice-based language around food, these organizations may unintentionally co-opt the local food justice movements. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2015

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