<p> The photocatalytic reaction has been integrated as a developing technology for various applications such as air and water remediation, and self-cleaning surfaces. The photocatalysis is an emerging pathway of heterogeneous photocatalysis and physical chemistry. In heterogeneous photocatalysis, semiconductor compounds, mainly TiO₂, ZnO, CdS, and WO₃, have been utilized especially for water treatment and contaminant degradation. Various pollutants, such as aromatic compounds, dyes and surface active agents, can be degraded with photocatalytic techniques. Ultraviolet light and visible light are the most important sources of radiation to conduct photocatalytic reactions. </p><p> In this study, we have developed a combined method using microfluidics and photocatalysis for wastewater treatment. This technique represents a promising solution for contaminant degradation that has advantages such as continuous operation, large surface area to volume ratio, rapid response, and fine flow control. The experiment was conducted by exposing samples to UV light with methylene blue as the model pollutant and titanium dioxide (TiO₂) as the catalyst. The degradation of methylene blue was monitored with spectrophotometry. The effects of variables, such as residence time, chip thickness and intensity have been investigated. The photocatalytic degradation has been determined to be a pseudo-first-order reaction with a rate constant (0.18 <i>C</i><i>_C</i>^0.334) related to catalyst concentration. Once optimized, this system could be scaled out to process wastewater at a larger scale.</p>

This research study investigates the pile set-up phenomenon for clayey soils and develops the models to predict pile set-up resistance at a certain time after the end of driving (EOD). The increase of pile resistance after EOD is known as pile set-up. To fulfill this objective, a total number of twelve prestressed concrete (PSC) test piles were driven in different soil conditions of Louisiana. In addition, dynamic load tests (DLT) and static load tests (SLT) were usually performed to verify the axial resistances of piles at specific times after EOD, as well as to quantify the amount of increase in resistance compared to the EOD (i.e., set-up). The focus of this research was to calculate the resistance of individual soil layers along the length of the pile. In order to implement this goal, all the test piles were instrumented with vibrating wire strain gages. Vibrating wire piezometers and pressure cells were also installed in the pile face in order to calculate the dissipation of excess pore water pressure, together with the corresponding increase in effective stress, respectively with time. The Case Pile Wave Analysis Program (CAPWAP) was performed in all the DLT data, in order to calculate the resistance of individual soil layers. Logarithmic set-up parameter A of individual soil layers were calculated using the unit side resistance (fs). The set-up parameter A was tried to correlate with different soil properties. With the aid of Statistical Analysis Software (SAS), detailed regression analyses were performed to develop models with incorporated soil properties. Five different levels of empirical models were developed in order to estimate the amount of set-up. In addition, one set-up model was developed directly from the in-situ test data (corrected cone tip resistance, qt). Load resistance factor calibration was performed in order to calibrate the set-up factor (ϕset-up). The developed models were implemented to predict the amount of resistance at four different time intervals after EOD. Finally, the statistical parameters of measured resistance to predict resistance were applied to calibrate the set-up factor (ϕset-up) and to incorporate that factor into the LRFD framework.

No description available.

No description available.

<p> The main aim of the study was to introduce new filtering techniques to better the prediction of subsurface water contaminant transport. Hybrid nudging-ensemble Kalman filter (HNEnKF) and ensemble adjustment Kalman filter were proposed in this study. EnKF with traditional nudging were gradually applied promptly in the case of the HNEnKF. Other techniques whose performance were evaluated along with HNEnKF are a numerical method, ensemble Kalman filter, and ensemble adjustment Kalman filter. In this study, the HNEnKF and the EAKF are expected to improve in robustness and convergence due to the nudging properties and the assimilation of observations with a nonlinear relation to model state variables respectively. To appraise the HNEnKF and EAKF techniques, the numerical (finite difference) method and EnKF assimilation method were used. These simulations were executed with a three-dimension subsurface contaminant transport model with a first-order decay rate parameter.</p><p> A summary of this research are outlined below: </p><p> &bull; To investigate the performance of HNEnKF and EAKF data assimilation technique in subsurface water contaminant transport modeling compared to the numerical solution and ensemble Kalman filter technique.</p><p> &bull; To apply HNEnKF and EAKF data assimilation scheme in subsurface water contaminant transport.</p>

Six years following the Deepwater Horizon oil spill, buried MC252 oil persists on a beach segment in Fourchon, LA due to the natural anaerobic conditions of tidal groundwater. A field trial of in situ aerobic bioremediation of buried oil began on July 2015. Oxygen was added to the subsurface using Waterloo emitters which deliver O2 through diffusion via pressurized tubing in fixed groundwater wells. The multi-well injection system provided sufficient oxygen concentration in the groundwater in the immediate area of the emitters, resulting in a shift in the composition of the diverse, halophilic, hydrocarbon-degrading microbial population. Stable isotopic and radiocarbon data from dissolved inorganic carbon provided evidence of crude oil mineralization post-aeration, even in areas that had the highest level of contamination. Weathering ratios for 3-ring PAHs were reduced post-aeration, indicating increased rates of degradation of phenanthrenes and dibenzothiophenes. Serum bottle studies were conducted to analyze biodegradation of PAHs and alkanes as a response to adding varying levels of O2 over time. Oxygen amendments were found to stimulate biodegradation of recalcitrant PAHs more effectively in less oily sediments than in sediments with higher oil concentrations. The minimum oxygen amendments in this study were sufficient in shifting the microbial population to a more effectual hydrocarbon degrading community structure.

Bridges built today are larger, but also lighter, more slender, and more efficient structures than they were a century ago. As the free span of future suspension bridges increases, so does the need for reducing dead loads. Using Fiber Reinforced Polymer (FRP) deck for suspension bridges is one way to achieve significantly lighter dead loads. Although the cost of FRP materials is more than double the cost of conventional concrete and steel deck, the hypothesis of this research is that the savings in the anchoring system and foundation and the reduction in weight of the main cables and suspenders will result in an overall cost reduction. It is also the hypothesis of this research that the use of FRP deck will impair the aerodynamic stability of suspension bridges. Significant studies have been performed on the use of FRP materials in bridge structures. The Federal Highway Administration initiated research on FRP composite bridge decks in the early 1980s, primarily focused on deck strength and stiffness. In addition, several research projects have been conducted for health monitoring and to assess the long-term performance of FRP materials in bridge construction. Overall, the results suggest that long-term structural response was consistent and well within acceptable strength and serviceability design limits. For the research described in this dissertation, a parametric study was performed considering several bridges of different spans, materials, soil conditions, and material unit prices to study the economic and aerodynamic implications of using FRP deck in suspension bridges . Two groups of suspension bridges with 200 m, 400 m, and 600 m free spans were designed, one group using a reinforced concrete deck and the other group using the much lighter FRP deck. Since soil conditions affect the design of the anchorage and the overall cost of the bridges, three different soil types were considered in this research. The three soil conditions that were considered in this research were sound rock, medium sand, and stiff clay. Then, the aerodynamic stability was examined for all of the bridges using Selberg’s approach. Three-dimensional finite element analyses was performed for each bridge to obtain the values for the torsional moment of inertia and the vertical and torsional frequencies. These values were used in Selberg’s equation to determine the flutter speed of each bridge. A linear elastic analysis was performed to validate the three-dimensional finite element analysis results. The predicted flutter speeds obtained from the linear elastic approach and the finite element approach were within 9% for all the spans and deck materials. The use of FRP deck reduced the predicted flutter speed of the 200 m span bridge, 400 m span bridge, and 600 m span bridges by 35%, 36%, and 37%, respectively. Sensitivity cost analysis was performed of the 200 m, 400 m and 600 m span bridges founded in three different soil types. The three soil types considered were sound rock, medium sand, and stiff clay. The maximum savings was realized in the case of the weakest soil with the least resistance to the main cables tension force: stiff clay. Consistent with the research hypothesis, the cost of the FRP deck is more than twice the cost of the concrete deck, yet the overall cost savings for using an FRP deck were 30% to 42% of the cost using a concrete deck depending on span length and soil conditions. While earlier studies have demonstrated that the life cycle cost analysis could be advantageous in the long term because it requires less maintenance, the findings of the research described in this dissertation showed that the use of FRP deck could result in a 30% to 42% reduction in initial construction cost.

A number of studies have been done in the field of driver distraction, specifically on the use of cell phone for either conversation or texting while driving. However, till now, researchers have focused on the driving performance of drivers when they were actually engaged in the task, i.e. during the texting or phone conversation event. The primary objective of this study is to analyze the post event effect of cell phone usage in order to verify whether the distracting effect lingers on after the actual event had ceased. The research utilizes a driving simulator study of thirty-six participants to test whether a significant decrease in driver performance occurs during and after cell phone usage (texting and conversation). The standard deviations of lane position and mean velocity was used as dependent measures to represent lateral and longitudinal control of the vehicle respectively. Linear mixed model with subject as a random factor and F-test for the equality of variance were used as statistical measures. The results from the study suggest that there was no significant decrease in driver performance during and after the cell phone conversation both laterally and longitudinally. On the contrary, during the texting event, a significant decrease in driver performance was observed both in the lateral and longitudinal control of the vehicle. The diminishing effect of texting on longitudinal control ceased immediately after the texting event but the diminishing effect of texting on lateral control lingered on for an average of 3.388 seconds. The number of text messages exchanged did not affect the magnitude and duration of the diminished lateral control. This indicates that the distraction and subsequent elevated crash risk of texting while driving linger on even after the texting event has ceased. Such finding has safety and policy implications in the fight to reduce distracted driving.

The fate of subsurface oiled sands collected from Fourchon Beach in Louisiana were determined while modifying biogeochemical controls on the degradation of PAHs. Groundwater on the beach has intrinsically low dissolved oxygen concentrations, which may limit natural biodegradation of the crude oil components. The intent of this research was to characterize the biogeochemical properties and degradability of oiled sands (with >10% of pore filled with MC252 oil) using a combination of laboratory flow-through reactor studies, field measurements and time-series microelectrode profiles of down-flow and cross flow geometries. Reactor experiments indicate that optimal conditions for substantial oil degradation are aerobic under advective-dispersive transport processes, and when amended with N and P (DO > 5 mg/L, > 6 mg-N/L, and > 0.6 mg-P/L). Cross-flow reactor studies, which mimic the presence of oiled sands over impermeable clayey deposits, showed no significant (P < 0.05) degradation of phenanthrenes or benzenothiophenes. Time series O2. microelectrode profiles showed that down-flow reactors had greater O2 penetration (>14 mm) than cross-flow geometries, which remained largely oxygen deficient at depths greater than 7 mm. Aerobic degradation of MC252 oil deposits on Fourchon Beach will be controlled by field transport mechanisms of available nutrients and oxygen. Due to low oxygen concentrations in natural groundwater at Fourchon Beach, in conjunction with low oxygen penetration depths and availability of nutrients, the rate of oil biodegradation in these environments is likely to be severely impeded.

UV disinfection performance was investigated under the influence of representative particle sources, including wastewater particles from secondary effluent in a wastewater treatment plant, river particles from surface water, floc particles from coagulated surface water, floc particles from coagulated process water in a drinking water treatment plant, and soil particles from runoff water (planned). Low-pressure (LP) and medium-pressure (MP) UV dose-response of spiked indicator bacteria <i>E. coli</i> was determined using a standard collimated beam apparatus with respect to different particle sources. Significant impacts of wastewater suspended solids (3. 13~4. 8 NTU) agree with the past studies on UV inactivation in secondary effluents. An average difference (statistical significance level of 5% or &alpha;=5%) of the log inactivation was 1. 21 for LP dose and 1. 18 for MP dose. In river water, the presence of surface water particles (12. 0~32. 4 NTU) had no influence on UV inactivation at all LP doses. However, when the floc particles were introduced through coagulation and flocculation, an average difference (&alpha;=5%) of the log inactivation was 1. 25 for LP doses and 1. 12 for MP doses in coagulated river water; an average difference (&alpha;=5%) of the log inactivation was 1. 10 for LP doses in coagulated process water. Chlorination was compared in parallel with UV inactivation in terms of particulate impacts. However, even floc-associated <i>E. coli</i> were too sensitive to carry out the chlorination experiment in the laboratory, indicating that chlorine seems more effective than UV irradiation on inactivation of particle-associated microorganisms. In addition, a comprehensive particle analysis supported the experimental results relevant to this study.