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Articles 1 - 13 of 13
Full-Text Articles in Engineering
A Comprehensive Assessment Methodology Based On Life Cycle Analysis For On-Board Photovoltaic Solar Modules In Vehicles, Mahmoud Abdelhamid
A Comprehensive Assessment Methodology Based On Life Cycle Analysis For On-Board Photovoltaic Solar Modules In Vehicles, Mahmoud Abdelhamid
All Dissertations
This dissertation presents a novel comprehensive assessment methodology for using on-board photovoltaic (PV) solar technologies in vehicle applications. A well-to-wheels life cycle analysis based on a unique energy, greenhouse gas (GHG) emission, and economic perspective is carried out in the context of meeting corporate average fuel economy (CAFE) standards through 2025 along with providing an alternative energy path for the purpose of sustainable transportation. The study includes 14 different vehicles, 3 different travel patterns, in 12 U.S. states and 16 nations using 19 different cost analysis scenarios for determining the challenges and benefits of using on-board photovoltaic (PV) solar technologies …
Earth Abundant Thin Film Technology For Next Generation Photovoltaic Modules, Githin Alapatt
Earth Abundant Thin Film Technology For Next Generation Photovoltaic Modules, Githin Alapatt
All Dissertations
With a cumulative generation capacity of over 100 GW, Photovoltaics (PV) technology is uniquely poised to become increasingly popular in the coming decades. Although, several breakthroughs have propelled PV technology, it accounts for only less than 1% of the energy produced worldwide. This aspect of the PV technology is primarily due to the somewhat high cost per watt, which is dependent on the efficiency of the PV cells as well as the cost of manufacturing and installing them. Currently, the efficiency of the PV conversion process is limited to about 25% for commercial terrestrial cells; improving this efficiency can increase …
Transformation Of Uranium In A Geological Environment, Derrell Hood
Transformation Of Uranium In A Geological Environment, Derrell Hood
All Theses
Incorporation of uranium into iron oxide minerals is a promising mechanism for the environmental immobilization of U(VI). In this study, synthesized hematite was doped with uranium and analyzed with SEM-EDS, TEM, XRD, and ICP-MS. The results of this analysis strongly indicate uranium incorporation into the mineral, as well as the possible presence of a co-precipitated uranium mineral clarkeite. Preliminary results also shows an increase in the amount of uranium associated with the hematite particles as a function of mineral aging. Cyclic Voltammetry (CV) was used to induce and characterize electrochemical changes of uranium in the doped hematite system; these changes …
An Experimental Investigation Towards Improvement Of Thermoelectric Properties Of Strontium Titanate Ceramics, Arash Mehdizadeh Dehkordi
An Experimental Investigation Towards Improvement Of Thermoelectric Properties Of Strontium Titanate Ceramics, Arash Mehdizadeh Dehkordi
All Dissertations
The direct energy conversion between heat and electricity based on thermoelectric effects is a topic of long-standing interest in condensed matter materials science. Experimental and theoretical investigations in order to understand the mechanisms involved and to improve the materials properties and conversion efficiency have been ongoing for more than half a century. While significant achievements have been accomplished in improving the properties of conventional heavy element based materials (such as Bi$_2$Te$_3$ and PbTe) as well as the discovery of new materials systems for the close-to-room temperature and intermediate temperatures, high-temperature applications of thermoelectrics is still limited to one materials system, …
Anaerobic And Aerobic Biodegradation Of The Oil Dispersant Components 1,2-Propanediol And 2-Butoxyethanol In Seawater, Benjamin Rhiner
Anaerobic And Aerobic Biodegradation Of The Oil Dispersant Components 1,2-Propanediol And 2-Butoxyethanol In Seawater, Benjamin Rhiner
All Theses
Oil spills are a recurring issue associated with fossil fuel consumption. The largest accidental oil spill in the history of the petroleum industry was the Deepwater Horizon explosion and seafloor well blowout, where the Deepwater Horizon oil rig exploded and sank, allowing the well to gush uncontrolled from April 20, 2010, until it was capped on July 15, 2010, releasing an estimated 210,000,000 gallons of oil. Oil dispersants were used in unprecedented quantities during the cleanup response to the spill with a total of 1,840,000 gallons of the dispersant COREXIT being applied. The goal of this research was to evaluate …
Investigation Of Concurrent Energy Harvesting From Ambient Vibrations And Wind, Amin Bibo
Investigation Of Concurrent Energy Harvesting From Ambient Vibrations And Wind, Amin Bibo
All Dissertations
In recent years, many new concepts for micro-power generation have been introduced to harness wasted energy from the environment and maintain low-power electronics including wireless sensors, data transmitters, controllers, and medical implants. Generally, such systems aim to provide a cheap and compact alternative energy source for applications where battery charging or replacement is expensive, time consuming, and/or cumbersome. Within the vast field of micro-power generation, utilizing the piezoelectric effect to generate an electric potential in response to mechanical stimuli has recently flourished as a major thrust area. Based on the nature of the ambient excitation, piezoelectric energy harvesters are divided …
An Examination Of Radionuclide Transport In The Vadose Zone Using Field Lysimeters, Michael Witmer
An Examination Of Radionuclide Transport In The Vadose Zone Using Field Lysimeters, Michael Witmer
All Theses
Understanding how radionuclides interact in the subsurface is important for the remediation of contaminated sites, assessment of risk due to radioactive waste disposal, and designing new radioactive waste management strategies. The current understanding of the geochemical behavior of radionuclides in the subsurface and more specifically the vadose zone has been developed through reactive transport modeling supplemented by laboratory experiments. Interactions between radionuclides with the mineral particles and organic matter in the vadose zone can be very complex and while laboratory experiments produce valuable data, few controlled, intermediate scale transport studies have been performed. In order to accurately predict vadose zone …
Spatial And Temporal Analysis Of Land Cover Change, Sedimentation And Water Quality In The Lake Issaqueena Watershed, South Carolina, Cassie Pilgrim
Spatial And Temporal Analysis Of Land Cover Change, Sedimentation And Water Quality In The Lake Issaqueena Watershed, South Carolina, Cassie Pilgrim
All Theses
Soil erosion and increased sediment yields within a watershed lead to impaired water quality, decreased availability of wildlife habitat and reduced recreational opportunities. While some sedimentation occurs naturally within a water system, most erosion processes are the result of anthropogenic activities across a landscape, namely changes in land use and land cover (LULC). This study was conducted to determine temporal and spatial sedimentation trends in the Lake Issaquena watershed using sonar logging equipment, geographic information systems (GIS) and limited hydrologic data from the Soil Conservation Service (1941 and 1949). Sediment deposition was analyzed in relation to several key factors that …
Gis-Based Suitability Modeling And Multi-Criteria Decision Analysis For Utility Scale Solar Plants In Four States In The Southeast Us, Kata Tisza
All Theses
Photovoltaic (PV) development shows significantly smaller growth in the Southeast U.S., than in the Southwest; which is mainly due to the low cost of fossil-fuel based energy production in the region and the lack of solar incentives. However, the Southeast has appropriate insolation conditions (4.0-6.0 KWh/m2/day) for photovoltaic deployment and in the past decade the region has experienced the highest population growth for the entire country. These factors, combined with new renewable energy portfolio policies, could create an opportunity for PV to provide some of the energy that will be required to sustain this growth. The goal of the study …
Design Of A High Temperature Subsurface Thermal Energy Storage System, Qi Zheng
Design Of A High Temperature Subsurface Thermal Energy Storage System, Qi Zheng
All Theses
Solar thermal energy is taking up increasing proportions of future power generation worldwide. Thermal energy storage technology is a key method for compensating for the inherent intermittency of solar resources and solving the time mismatch between solar energy supply and electricity demand. However, there is currently no cost-effective high-capacity compact storage technology available (Bakker et al., 2008). The goal of this work is to propose a high temperature subsurface thermal energy storage (HSTES) technology and demonstrate its potential energy storage capability by developing a solar-HSTES-electricity generation system. In this work, main elements of the proposed system and their related state-of-art …
Adsorption Of Synthetic Organic Chemicals: A Comparison Of Superfine Powdered Activated Carbon With Powdered Activated Carbon, Semra Bakkaloglu
Adsorption Of Synthetic Organic Chemicals: A Comparison Of Superfine Powdered Activated Carbon With Powdered Activated Carbon, Semra Bakkaloglu
All Theses
In literature, manufacturer-supplied powdered activated carbon has been ground to produce submicron particles with mean diameter lower than 1µm for use as an adsorbent during water treatment. Superfine powdered activated carbon (SPAC) can be used for removal of natural organic matter as well as synthetic organic chemicals (SOCs) from water. It has been suggested that SPAC has higher adsorption capacity than powdered activated carbon (PAC) due to larger external surface area and mesopore volume. Another advantage of SPAC over PAC is the faster uptake rate for both NOM and SOC during adsorption owing to small particle size. Therefore, understanding SPAC …
Isolated And Ephemeral Wetlands Of Southern Appalachia: Biotic Communities And Environmental Drivers Across Multiple Temporal And Spatial Scales, Joanna Hawley
All Dissertations
Throughout the world, wetlands are known to support a wide variety of taxa as well as high levels of biodiversity and species richness. Although the ecological significance of wetlands is well documented in the scientific literature, efforts to map and assess wetlands on regional or national scales (e.g., National Wetlands Inventory (NWI)) often overlook wetlands which are either very small (< 1 ha) or have ephemeral hydroperiods. While the vast majority of wetland research in the southeastern United States has focused on wetlands distributed across the coastal plain ecoregion, very little information exists on small and/or ephemeral wetlands in areas of southern Appalachia, although there are several notable exceptions. Despite the paucity of small wetland data in this region, the southeastern US is known as a hotspot for both aquatic biodiversity and species endemism. My goal with this project was to examine the biotic communities inhabiting small, ephemeral and geographically-isolated wetlands to identify the major environmental drivers that contribute to observed community patterns and species' distributions. I studied a set of small, mostly-ephemeral, mostly-isolated wetlands (N = 41) in the upper Piedmont and lower Blue Ridge ecoregions of South Carolina from January-June of 2010 and 2011 and focused my efforts on describing the structure, biotic communities and surrounding habitat characteristics of my study wetlands. I observed high levels of species richness and biodiversity in this previously-undocumented wetland system, despite the small size and ephemeral nature of study wetlands. My results indicated that the amphibian and benthic invertebrate communities of small, ephemeral wetlands responded to different environmental drivers (e.g., wetland depth, area, hydroperiod, canopy cover, surrounding land use types) occurring across multiple spatial and temporal scales. Additionally, the amphibian community was significantly influenced by a number of environmental variables occurring at both the within-pond scale and larger spatial scales (250 m, 500 m and 1 km surrounding land cover variables). By contrast, the benthic invertebrate community was significantly influenced primarily by variables occurring at the within-pond scale. This wetland system also served as both breeding and overwintering habitat for a variety of species such as wood frogs (Lithobates sylvatica), spotted salamanders (Ambystoma maculatum), bullfrogs (Lithobates catesbeiana), cricket frogs (Acris crepitans). This study highlights the ecological importance of small, ephemeral aquatic habitats in a region where little research exists regarding such systems; these often-unnoticed ecosystems are likely the result of a combination of historical anthropogenic and natural environmental process. These legacy wetlands (i.e., wetlands that are the unintended result of some human-induced environmental change in either the recent or long-term past) are found ubiquitously across the landscape and are often missed by coarse-filter mapping approaches (e.g., National Wetlands Inventory). I observed many study wetlands to be extremely small in size (< 0.05 ha) and that many wetlands were habitats of circumstance and opportunity rather than of permanence and predictability. The ephemerality of the majority of study wetlands demonstrates the biological significance of small, temporary habitats for many species requiring these habitats for breeding activity. Despite the small size and ephemeral nature of my study wetlands, I found that these wetlands represented a large proportion of amphibian biodiversity in the regional species pool and thus, are an important conservation feature at the local, landscape and regional scales. My study demonstrates that small, semi-isolated, mostly-ephemeral wetlands in southern Appalachia support high levels of biodiversity and are an important asset deserving of further study and conservation recognition.
Improved Oxidative Stability In Biodiesel Via Commercially-Viable Processing Strategies, Gregory Lepak
Improved Oxidative Stability In Biodiesel Via Commercially-Viable Processing Strategies, Gregory Lepak
All Theses
Biodiesel made from waste cooking oil (WCO) frequently requires antioxidants to meet oxidation stability specifications set forth in ASTM D6751 or EN 14214. In contrast, unrefined cottonseed oil (CSO), containing tocopherols and high concentrations of gossypol, a toxic polyphenolic antioxidant, is unique for biodiesel processing because it produces biodiesel resulting in higher oxidation stability. During biodiesel production, however, only a portion of these endogenous natural antioxidants are suspected to be retained. Because the economics of biodiesel manufacturing rely upon inexpensive sources of triglycerides, emphasis was placed upon developing improved alternative commercially-viable processing strategies where WCO is the main source of …