Thesis (M. S.)--Texas A&M University, 2005. / "December 2005." Title taken from PDF title screen (viewed October 23, 2007). Includes bibliographical references (p. 63-67) and appendix.

<p> Measurement of the vapor-liquid equilibrium (VLE) of fluid mixtures with many components presents a challenge. Data describing such mixtures, like fuels, are important for the development of alternative energy sources and to support forensic science, but there is a lack of suitable instrumentation to provide data with reasonable uncertainty for mixtures with many components. In this thesis, three different techniques for fluid characterization are explored: the advanced distillation curve (ADC), the advanced distillation curve with reflux (ADCR), and PLOT-cryoadsorption. Two pyrolysis fuels similar to gasoline and diesel fuel made from polypropylene were studied with respect to volatility, composition, and energy content using the advanced distillation curve. The diesel fuel demonstrated volatility very similar to previously measured diesel fuels. The gasoline was less volatile than petroleum-derived counterparts and did not meet specifications.</p><p> Two pyrolysis crude oils made from ponderosa pine and dairy manure were assessed using the ADC coupled to an approach for characterizing fluids with multiple, immiscible liquid phases. Both oils contained high water levels and would require further refinement before use. The organic phases of each oil contained components indicative of the feedstock used.</p><p> A modification of the ADC method, the advanced distillation curve with reflux, was introduced as an approach to measuring the VLE of fluids with many components. The ADCR additionally approximates the weathering of an ignitable liquid that occurs during an arson fire and measures VLE across a range of weathered conditions. The method was demonstrated using two simple mixtures. The measurements agreed well with models, indicating that ADCR is a suitable VLE metrology.</p><p> Vapor-liquid equilibrium data are crucial for interpreting the results of headspace characterization used often in forensic science. One headspace method, portable PLOT-cryoadsorption, was tested in a series of experiments in the laboratory and then deployed for the first time in a field environment that simulated a cargo container. The technology was found to be rapid and sensitive to a variety of compounds of interest to forensic science. Each of the three techniques described in this thesis contribute valuable property data for multicomponent mixtures, towards the development of high-quality predictive models.</p><p>

<p> Knowledge of colloid mobility is important for understanding nutrient cycling, the transport of some contaminants, and for developing environmental remediation systems such as geologic filters. The interaction forces between colloids and soil materials are central to colloid transport and immobilization. These forces act at the microscale (nanometers to microns) and include: fluid drag (friction), Brownian motion, gravity and buoyancy, and fluid chemical forces (including DLVO and van der Waals mechanisms). Most vadose zone studies, however, consider colloids at the continuum scale in terms of solute transport mechanisms using parametrized forms of the advection-dispersion equation and absorption isotherms. A comprehensive, generally applicable, well-documented and publicly available framework for simulating colloids at the microscale is still lacking. </p><p> Colloid transport and mobility are mechanisms that fundamentally occur at the microscale. As such, representation of the pore-structure needs to be obtained that is meaningful for the pore-scale fluid flow field and colloid mobility (pore-scale colloidal force balances cause the colloidal transport field to be different from the fluid flow field). At the same time, the pore-structure needs to be relevant for continuum-scale experiments or simulations. There are two ways by which a pore-structure can be obtained: by direct three-dimensional imaging (typically with x-ray tomographic techniques) or by reconstruction techniques that yield a synthetic, but presumably representative, pore-structure. Both techniques are examined in this dissertation, but the synthetic route must be used if little micro-scale information is available. </p><p> This dissertation addresses three main objectives. In chapter 2 it addresses the relation between image quality obtained with two different x-ray tomography techniques (a synchrotron and an industrial scanner) and the obtained flow field. Chapter 3 discusses the development of the LB-Colloids software package, while chapter 4 applies the code to data obtained from a breakthrough experiment of nanoparticulate TiO₂. </p><p> In chapter 2, pore-scale flow fields for Berea sand stone and a macropore soil sample were obtained with lattice Boltzmann simulations which were volume-averaged to a sample-scale permeability and verified with an observed sample-scale permeability. In addition, the lattice Boltzmann simulations were verified with a Kozeny-Carman equation. Results indicate that the simulated flow field strongly depends on the quality of the x-ray tomographic imagery and the segmentation algorithm used to convert gray-scale tomography data into binary pore-structures. More complex or advanced segmentation algorithms do not necessarily produce better segmentations when dealing with ambiguous imagery. It was found that the KC equation provided a reliable initial assessment of error when predicting permeability and can be used as a quick evaluation of whether simulations of the micro-scale flow field should be pursued. In the context of this study, this chapter indicated that LB is able to generate relevant pore-scale flow fields that represent sample-scale permeabilities. However, because the remainder of the study was focused on the development of a pore-scale colloid mobility framework we decided to focus primarily on synthetically-generated pore-structures. This also allowed us to focus on actual mechanisms that were free of imaging and segmentation artifacts. </p><p> Chapter 3 discusses the development of the LB-Colloids package. This simulation framework is able to simulate large collections of individual colloids through pore representations and porous media. The general workflow for users is as follows: 1) Obtain a pore structure by tomographic imaging or by synthetic means. The latter can be accomplished though the included PSPHERE module which is able to generate a random porous medium using user-supplied porosity and particle size. 2) The pore-scale fluid flow field in the porous medium is generated with a lattice Boltzmann method and a user-specified body force that controls the volume averaged Darcy velocity. 3) Mobility and attachment/detachment of colloids is simulated by accounting of the force balance (fluid drag, Brownian motion, gravity and buoyancy forces, and fluid-chemical forces including DLVO and van der Waals mechanisms). Colloid mobility is carried out at a submicron to nanometer scale and requires grid refinement of the LB flow field. To speed up computations the fluid-chemical forces are precomputed for every grid cell. </p><p> Because of computational considerations, the LB-Colloids package is presently only able to deal with 2D representations of the porous medium. Code-development and testing (chapter 4) would have taken too long for a full 3D approach. The main draw-back of the 2D approach is that these cannot accurately represent 3D pore-structures. However, no fundamental &ldquo;new&rdquo; mechanisms are needed for a 3D approach and we expect that this can be easily built into the clean and well-documented LB-colloids code. The LB-Colloids framework is applied on data obtained from a break-through experiment of TiO₂ nanoparticles. (Abstract shortened by ProQuest.) </p><p>

<p> Airborne hydrographic surveys are routinely used to create and update nautical charts around the world. This research is intended to assist in maximizing the utility of the data products made available from those surveys in accordance with the current survey&mdash;once, use&ndash;many&mdash;times initiatives. Specifically, this project evaluates the feasibility of using the data available airborne hydrographic systems that utilize bathymetric lasers and hyperspectral sensors to estimate the concentration of suspended particulate matter (SPM). SPM is sometimes also called suspended sediment. The ability to chart spatial distributions of SPM utilizing hydrographic survey systems already in operation will assist researchers, managers, and stakeholders of the areas thus surveyed. </p><p> Ship-based <i>in situ</i> measurements of multiple IOPs at up to twelve wavelengths were gathered in the northern Gulf of Mexico during five cruises between 2009 and 2010. One hundred sixty-nine IOP based SPM models using all available quality-checked data were developed and evaluated for performance. This large number of algorithms allowed for a comparison of the effectiveness of the IOPs that may be derived from airborne hydrographic surveys with other IOPs that may or may not be so readily available. The results were varied. </p><p> The apparent optical property remote sensing reflectance (R_rs) is a data product of hyperspectral sensors that are often part of airborne survey systems. A method to predict suspended particulate matter concentration using the wavelength of maximum intensity for R_rs is presented. This represents a new way to estimate suspended particulate matter concentration from an airborne platform. </p><p> Due to the methods used for gathering the in-situ data, it was necessary to consider the validity of the assumption that consecutive water column profiling events from a ship represent the same sampling environment. Though this research demonstrates that this assumption is false, it does indicate that consecutive profiling events do sample the same water properties in many instances and that with a little care, datasets gathered this way may be used in research efforts similar to this one. Finally, the distribution and selected properties of SPM concentrations in the northern Gulf of Mexico were examined.</p><p>

<p> Across the planet, climate change is altering the way human societies interact with the environment. Amplified climate change at high latitudes is significantly altering the structure and function of ecosystems, creating challenges and necessitating adaptation by societies in the region that depend on local ecosystem services for their livelihoods. Rural communities in Interior Alaska rely on plants and animals for food, clothing, fuel and shelter. Previous research suggests that climate-induced changes in environmental conditions are challenging the abilities of rural residents to travel across the land and access local resources, but detailed information on the nature and effect of specific conditions is lacking. My objectives were to identify climate-related environmental conditions affecting subsistence access, and then estimate travel and access vulnerability to those environmental conditions. I collaborated with nine Interior Alaskan communities within the Yukon River basin and provided local residents with camera-equipped GPS units to document environmental conditions directly affecting access for 12 consecutive months. I also conducted comprehensive interviews with research participants to incorporate the effects of environmental conditions not documented with GPS units. Among the nine communities collaborating on this research, 18 harvesters documented 479 individual observations of environmental conditions affecting their travel with GPS units. Environmental conditions were categorized into seven condition types. I then ranked categories of conditions using a vulnerability index that incorporated both likelihood (number of times a condition was documented) and sensitivity (magnitude of the effect from the condition) information derived from observations and interviews. Changes in ice conditions, erosion, vegetative community composition and water levels had the greatest overall effect on travel and access to subsistence resources. Environmental conditions that impeded travel corridors, including waterways and areas with easily traversable vegetation (such as grass/sedge meadows and alpine tundra), more strongly influenced communities off the road network than those connected by roads. Combining local ecological knowledge and scientific analysis presents a broad understanding of the effects of climate change on access to subsistence resources, and provides information that collaborating communities can use to optimize adaptation and self-reliance. </p><p>

abstract: The atmosphere contains a substantial amount of water soluble organic material, yet despite years of efforts, little is known on the structure, composition and properties of this organic matter. Aqueous phase processing by fogs and clouds of the gas and particulate organic material is poorly understood despite the importance for air pollution and climate. On one hand, gas phase species can be processed by fog/cloud droplets to form lower volatility species, which upon droplet evaporation lead to new aerosol mass, while on the other hand larger nonvolatile material can be degraded by in cloud oxidation to smaller molecular weight compounds and eventually CO2. In this work High Performance Size Exclusion Chromatography coupled with inline organic carbon detection (SEC-DOC), Diffusion-Ordered Nuclear Magnetic Resonance spectroscopy (DOSY-NMR) and Fluorescence Excitation-Emission Matrices (EEM) were used to characterize molecular weight distribution, functionality and optical properties of atmospheric organic matter. Fogs, aerosols and clouds were studied in a variety of environments including Central Valley of California (Fresno, Davis), Pennsylvania (Selinsgrove), British Columbia (Whistler) and three locations in Norway. The molecular weight distributions using SEC-DOC showed smaller molecular sizes for atmospheric organic matter compared to surface waters and a smaller material in fogs and clouds compared to aerosol particles, which is consistent with a substantial fraction of small volatile gases that partition into the aqueous phase. Both, cloud and aerosol samples presented a significant fraction (up to 21% of DOC) of biogenic nanoscale material. The results obtained by SEC-DOC were consistent with DOSY-NMR observations. Cloud processing of organic matter has also been investigated by combining field observations (sample time series) with laboratory experiments under controlled conditions. Observations revealed no significant effect of aqueous phase chemistry on molecular weight distributions overall although during cloud events, substantial differences were apparent between organic material activated into clouds compared to interstitial material. Optical properties on the other hand showed significant changes including photobleaching and an increased humidification of atmospheric material by photochemical aging. Overall any changes to atmospheric organic matter during cloud processing were small in terms of bulk carbon properties, consistent with recent reports suggesting fogs and clouds are too dilute to substantially impact composition. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2014

<p> Coastal erosion is an issue of concern for Louisiana, in the United States, and for all other coastal communities in the world. Among many coastal protection and restoration technologies, shoreline protection structures focus on wave reductions to prevent waves from hitting the coastal landforms directly. A novel technology called the Wave Suppression and Sediment Collection (WSSC) system focuses on solving the limitations of conventional shoreline protection structures regarding mobility, constructability, and sustainability. The primary goals of this study are to optimize the WSSC units for wave reduction and sediment transport and to verify the performance of this technology in an actual field environment. Computational Fluid Dynamics (CFD) simulations were carried out to optimize the designs of the units in terms of pipe diameters and face slope. Results have indicated that increasing pipe diameters decreases wave reduction and increases sediment transport ability of the units. Further, it was found that increasing the face slope decreases the wave reduction ability; however, no effect was found on the sediment transport efficiency. Parametric optimization suggested that a porosity (open-to-total area ratio) of 30% should yield satisfactory wave reduction and balanced sediment transport by the units. For better output from the units, the designs should be modified according to site-specific requirements. Field site investigations involved Surface Elevation Table (SET) surveying and marker clay experiments. SET surveys showed significant sediment accumulation over eleven months behind the units. Also, no significant change was observed at the control site over three months, which proves the effectiveness of the technology in stopping erosion and facilitating land building. Marker clay experiments validated the SET measurements and proved that there was a significant amount of sediment deposition over the white Feldspar clay layer over six months. This strengthens the conclusion that the WSSC units can be used successfully in a Louisiana marsh environment to battle coastal erosion and land loss.</p><p>

<p> With the increasing use of technology in the workplace, many jobs are becoming more sedentary. The purpose of this study was to establish a quantitative baseline measure of occupational physical activity (OPA) in active and sedentary workers. Two activity trackers (Fitbit Charge HR&trade; and Hexoskin) were used to assess activity measures (step count, heart rate and energy expenditure) among workers during their work shift. The first objective of the study was to assess the agreement between two types of accelerometer-based activity trackers as measures of OPA. The second objective of this study was to assess differences in measures of OPA among workers in physically active and sedentary work environments. There was a statistically significant difference in measures of total step counts between the two devices. When comparing active and sedentary workers there were also statistically significant differences in measures of step counts, mean percent heart rate increase, maximum heart rate range and energy expenditure. Conclusion: The Fitbit Charge HR&trade; and Hexoskin had significant differences in measures of step counts and heart rate. When comparing active and sedentary workers, there were significant differences in measures of step counts, mean heart rate, maximum heart rate range required by job, and energy expenditure. The results of the present study provide quantitative evidence that active workers require greater physiologic demands than sedentary workers.</p>

<p> Community solar is a renewable energy practice that&rsquo;s been adopted by multiple U.S. states and is being considered by many more, including the state of Oregon. A recent senate bill in Oregon, called the &ldquo;Clean Electricity and Coal Transition Plan&rdquo;, includes a provision that directs the Oregon Public Utility Commission to establish a community solar program for investor-owned utilities by late 2017. Thus, energy consumers in Portland will be offered participation in community solar projects in the near future. Community solar is a mechanism that allows ratepayers to experience both the costs and benefits of solar energy while also helping to offset the proportion of fossil-fuel generated electricity in utility grids, thus aiding climate change mitigation. </p><p> For community solar to achieve market success in the residential sector of Portland, ratepayers of investor-owned utilities must socially accept this energy practice. The aim of this study was to forecast the potential social acceptance of community solar among Portland residents by measuring willingness to participate in these projects. Additionally, consumer characteristics, attitudes, awareness, and knowledge were captured to assess the influence of these factors on intent to enroll in community solar. The theory of planned behavior, as well as the social acceptance, diffusion of innovation, and dual-interest theories were frameworks used to inform the analysis of community solar adoption. These research objectives were addressed through a mixed-mode survey of Portland residents, using a stratified random sample of Portland neighborhoods to acquire a gradient of demographics. 330 questionnaires were completed, yielding a 34.2% response rate. </p><p> Descriptive statistics, binomial logistic regression models, and mean willingness to pay were the analyses conducted to measure the influence of project factors and demographic characteristics on likelihood of community solar participation. Roughly 60% of respondents exhibited interest in community solar enrollment. The logistic regression model revealed the percent change in utility bill (essentially the rate of return on the community solar investment) as a dramatically influential variable predicting willingness to participate. Community solar project scenarios also had a strong influence on willingness to participate: larger, cheaper, and distant projects were preferred over small and expensive local projects. Results indicate that community solar project features that accentuate affordability are most important to energy consumers. Additionally, demographic characteristics that were strongly correlated with willingness to enroll were politically liberal ideologies, higher incomes, current enrollment in green utility programs, and membership in an environmental organization. Thus, the market acceptance of community solar in Portland will potentially be broadened by emphasizing affordability over other features, such as community and locality. </p><p> Additionally, I explored attitudinal influences on interest in community solar by conducting exploratory factor analysis on attitudes towards energy, climate change, and solar barriers and subsequently conducting binomial logistic regression models. Results found that perceiving renewable energy as environmentally beneficial was positively correlated with intent to enroll in community solar, which supported the notion that environmental attitudes will lead to environmental behaviors. The logistic regression model also revealed a negative correlation between community solar interest and negative attitudes towards renewable energy. Perceptions of solar barriers were mild, indicating that lack of an enabling mechanism may be the reason solar continues to be underutilized in this region.</p><p>

<p> Environmental sustainability requires resource management that takes future generations into account. The present generation has witnessed changes across the planet, unprecedented in human history and disrupting communities and cities around the world, due to shifting global climate. This is primarily the result of fossil fuels, which powered modern civilization but dramatically increased levels of CO₂ and other greenhouse gases, and may be the least sustainable aspect of human civilization. Chapter 1 justifies the research from an environmental perspective and provides initial research parameters. Thin film photovoltaic (PV) modules are reported the most sustainable among energy production technologies currently available. Electrodeposited PV layers offer significant improvement to sustainability metrics over current thin film production methods, at reduced cost, but have rarely been demonstrated on an industrial scale. </p><p> Quasi-rest potential (QRP) ultimately led to large-scale, electrodeposited thin film CdTe modules. An in-situ material characterization technique that allows adjustment of the deposition voltage (V_dep) to match the exact experimental conditions, QRP enabled precise control of deposit stoichiometry and crystallinity. Chapter 2 discusses theory and literature regarding QRP, and introduces the open-circuit voltage transient (V_ocT), developed by the present research for analyzing QRP as a function of both V_dep and time. V_ocT data from a CdTe ethylene glycol bath matches details and speculations from the literature. </p><p> Although predicted to have wide applicability, experimental QRP data have never been published for compounds unrelated to CdTe. Chapter 3 discusses V_ocTs performed in pursuit of electrodeposited CuInS₂, demonstrating functionality as a QRP scan in a variety of ethylene glycol solutions. Stoichiometries of deposited films were improved by using the V_ocT to determine appropriate plating voltages. V_ocTs enabled QRP, in-situ rest potential (E_M2), and current simultaneously vs V_dep and correlated with cyclic voltammetry experiments. Films approaching stoichiometric CuInS₂ were generally obtained around -1 V vs Ag/AgCl, just noble of onset of metallic indium deposition, with a QRP around -0.8 V and E_M2 between -0.55 V and -0.6 V. Sulfur content of deposited films could also be significantly increased during deposition using open-circuit techniques based on V_ocT data. Serendipitous production of large copper sulfide nanowires is briefly discussed.</p><p>