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(1 - 5 of 5)
- Title
- DERIVING THE DENSITY OF STATES FOR GRANULAR CONTACT FORCES.
- Creator
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Metzger, Philip, Bhattacharya, Aniket, University of Central Florida
- Abstract / Description
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The density of single grain states in static granular packings is derived from first principles for an idealized yet fundamental case. This produces the distribution of contact forces P_f(f) in the packing. Because there has been some controversy in the published literature over the exact form of the distribution, this dissertation begins by reviewing the existing empirical observations to resolve those controversies. A method is then developed to analyze Edwards' granular contact force...
Show moreThe density of single grain states in static granular packings is derived from first principles for an idealized yet fundamental case. This produces the distribution of contact forces P_f(f) in the packing. Because there has been some controversy in the published literature over the exact form of the distribution, this dissertation begins by reviewing the existing empirical observations to resolve those controversies. A method is then developed to analyze Edwards' granular contact force probability functional from first principles. The derivation assumes Edwards' flat measure -- a density of states (DOS) that is uniform within the metastable regions of phase space. A further assumption, supported by physical arguments and empirical evidence, is that contact force correlations arising through the closure of loops of grains may be neglected. Then, maximizing a state-counting entropy results in a transport equation that can be solved numerically. For the present it has been solved using the "Mean Structure Approximation," projecting the DOS across all angular coordinates to more clearly identify its predominant features in the remaining stress coordinates. These features are: (1) the Grain Factor related to grain stability and strong correlation between the contact forces on the same grain, and (2) the Structure Factor related to Newton's third law and strong correlation between neighboring grains. Numerical simulations were then performed for idealized granular packings to permit a direct comparison with the theory, and the data including P_f(f) were found to be in excellent agreement. Where the simulations and theory disagree, it is primarily due to the coordination number Z because the theory assumes Z to be a constant whereas in disordered packings it is not. The form of the empirical DOS is discovered to have an elegant, underlying pattern related to Z. This pattern consists entirely of the functional forms correctly predicted by the theory, but with only slight parameter changes as a function of Z. This produces significant physical insight and suggests how the theory may be generalized in the future.
Show less - Date Issued
- 2005
- Identifier
- CFE0000381, ucf:46325
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0000381
- Title
- Cost and Environmental Impacts of Leachate Nitrogen/Phosphorus Management Approaches.
- Creator
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Alanezi, Alaa, Reinhart, Debra, Randall, Andrew, Sadmani, A H M Anwar, University of Central Florida
- Abstract / Description
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Landfill leachate is a challenging wastewater to discharge into municipal wastewater treatment plants (WWTPs), the most common approach for leachate management, due to the presence of contaminants that may affect the performance of the treatment plant. Treatment, disposal, and transportation of leachate are expensive and therefore a concern. Currently, sidestream treatment is becoming increasingly common in WWTPs prior to returning the liquid to the plant influent. For this research, a new...
Show moreLandfill leachate is a challenging wastewater to discharge into municipal wastewater treatment plants (WWTPs), the most common approach for leachate management, due to the presence of contaminants that may affect the performance of the treatment plant. Treatment, disposal, and transportation of leachate are expensive and therefore a concern. Currently, sidestream treatment is becoming increasingly common in WWTPs prior to returning the liquid to the plant influent. For this research, a new treatment scheme is introduced combining centrate and leachate to reduce contaminants, recover phosphorous and nitrogen through struvite precipitation, and reduce energy requirements through anaerobic ammonium oxidation (Anammox). By combining the two waste streams, the respective limited nutrients (nitrogen in centrate and nitrogen in leachate) can be removed in a low cost chemical treatment resources can be recovered. Carbon contaminants and remaining nutrients can be removed in subsequent innovative biological treatment units. The objective of this thesis is to conduct a cost analysis and environmental assessment of the proposed novel treatment approach and to compare it to more traditional landfill on-site leachate treatment approaches (e.g., membrane bioreactors (MBR) and sequencing batch reactors (SBR)). The study was completed with the use of spreadsheet-based models. Spreadsheets have been developed to evaluate treatment costs (Capital + O(&)M) for both the proposed nutrient recovery/biological and traditional on-site leachate treatments. Transportation costs of leachate to the WWTP have been studied and analyzed by the use of a spreadsheet model as a function of distance. Results suggest that treatment using Struvite (-) Aerobic Granular Sludge (-) Anammox (SGA) was higher in cost compared to traditional approaches. However, positive outcomes from this process include: lower N_2 O emissions, lower power consumption, struvite fertilizer, and overall recovery of nitrogen and phosphorus with the combination of centrate and leachate.
Show less - Date Issued
- 2018
- Identifier
- CFE0007147, ucf:52310
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007147
- Title
- Neurological profile of older ApoE-PON1 double knockout mice.
- Creator
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Mitra, Connie, Parthasarathy, Sampath, Kim, Yoon-Seong, Zhao, Jihe, University of Central Florida
- Abstract / Description
-
Atherosclerosis is a cardiovascular disease where plaques made up of lipids in the form of cholesterol ester build up in the carotid and innominate arteries that supply blood to the brain. Accumulation of the plaques limit the flow of blood and nutrients to the brain, leading to diminished oxygen supply, increased oxidative stress and cell death. All these have been implicated in Alzheimer's disease (AD). Alzheimer's disease, a chronic, progressive, age related neurodegenerative disorder is...
Show moreAtherosclerosis is a cardiovascular disease where plaques made up of lipids in the form of cholesterol ester build up in the carotid and innominate arteries that supply blood to the brain. Accumulation of the plaques limit the flow of blood and nutrients to the brain, leading to diminished oxygen supply, increased oxidative stress and cell death. All these have been implicated in Alzheimer's disease (AD). Alzheimer's disease, a chronic, progressive, age related neurodegenerative disorder is the most common form of dementia in the elderly accounting for 60-80% of the cases. Clinically, Alzheimer's disease is characterized by loss of memory, damage of brain tissues, and neuronal and synaptic loss. Pathologically, it is delineated by accumulation of amyloid beta and tau proteins forming senile plaques and neurofibrillary tangles respectively. Apolipoprotein E (ApoE) polymorphism, increased oxidative stress and products of lipid peroxidation are associated with atherosclerosis and Alzheimer's disease. ApoE is a glycosylated protein that mediates plasma lipoprotein metabolism. ApoE isoforms have differential effect on amyloid beta aggregation and clearance, thus playing an important role in Alzheimer's pathology. Serum paraoxonase 1 (PON1) is a lipoprotein associated antioxidant enzyme that prevents lipid peroxidation. S100B protein is a plasma biomarker, altered expression of which has been implied in AD. We propose the hypothesis that combined deficiencies in apolipoprotein E and antioxidant defense (established by the lack of PON1), together with dyslipidemia and development of carotid atherosclerosis in aging mice would reflect Alzheimer's pathology. The brains of young and old ApoE-PON1 double knockout (DKO) mice and control C57BL/6J mice were harvested. Atherosclerotic lesions were quantified by Image J. RNA was isolated, cDNA was synthesized and quantitative RT-PCR was performed to detect mRNA levels of S100B. Blood levels of S100B protein was measured by ELISA. Brain tissues were stained with Hematoxylin and Eosin stain and 4G8 immunostain to detect histopathological changes. The blood brain barrier (BBB) is altered in AD resulting in increased permeability and vascular dysfunction. The vascular permeability of BBB was analyzed by Evans Blue Dye (EBD) assay. The results showed that the older DKO mice had severe carotid atherosclerosis, increased levels of serum S100B protein and elevated mRNA levels of S100B. Histological examination showed the presence of characteristic hallmarks of AD. The leakage of EBD into brain parenchyma indicated disruption of BBB. The results suggest that diminished blood flow and nutrient supply to the brain due to atherosclerosis and increased oxidative stress might contribute to Alzheimer's pathology. We suggest that older ApoE-PON1 DKO mice may serve as a model of Alzheimer's disease and prevention of atherosclerosis might promote regression of Alzheimer's disease.
Show less - Date Issued
- 2016
- Identifier
- CFE0006483, ucf:51407
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006483
- Title
- Ozone and GAC Treatment of a Central Florida Groundwater for Sulfide and Disinfectant By-Product Control.
- Creator
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Lamoureux, Tara, Duranceau, Steven, Randall, Andrew, Wang, Dingbao, University of Central Florida
- Abstract / Description
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This study evaluated the combination of ozone and granular activated carbon (GAC) treatment for the removal of sulfide and disinfection byproduct (DBP) precursors in drinking water at the pilot-scale. The research conducted was performed at the Auxiliary (Aux) and Main Water Treatment Plants (WTPs) in Sanford, Florida. Both WTPs rely upon groundwater sources that contain total sulfide ranging from 0.02 to 2.35 mg/L and total organic carbon (TOC) ranging from 0.61 to 2.20 mg/L. The Aux WTP's...
Show moreThis study evaluated the combination of ozone and granular activated carbon (GAC) treatment for the removal of sulfide and disinfection byproduct (DBP) precursors in drinking water at the pilot-scale. The research conducted was performed at the Auxiliary (Aux) and Main Water Treatment Plants (WTPs) in Sanford, Florida. Both WTPs rely upon groundwater sources that contain total sulfide ranging from 0.02 to 2.35 mg/L and total organic carbon (TOC) ranging from 0.61 to 2.20 mg/L. The Aux WTP's raw water contains, on average, 88% more sulfide and 24% more TOC than the Main WTP. Haloacetic acids (HAA5) and total trihalomethanes (TTHMs) comprise the regulated forms of DBPs. HAA5 are consistently below the maximum contaminant level (MCL) of 60 ?g/L, while TTHM ranges from 70 to 110 ?g/L, at times exceeding the MCL of 80 ?g/L in the distribution system. Ozone alone removed total sulfide and reduced UV-254 by about 60% at the Aux Plant and 35% at the Main Plant. Producing an ozone residual of 0.50 mg/L prevented the formation of bromate while removing approximately 35 to 60% concentration of DBP precursors as measured by UV-254. Operating the GAC unit at an empty bed contact time (EBCT) of 10 minutes for the Aux Plant and 5.5 minutes for the Main Plant resulted in 75% and 53% of UV-254 reduction, respectively. The average 120 hour TTHM formation potential for the Aux and Main Plants were 66 ?g/L and 52 ?g/L, respectively, after treatment by ozone and GAC. GAC exhaustion was deemed to have occurred after seven weeks for the Aux Plant and eleven weeks for the Main Plant. The GAC columns operated in three phases: an adsorption phase, a transitional phase, and a biologically activated carbon (BAC) phase. The GAC adsorption phase was found to produce the lowest TTHMs; however, TTHMs remained less than 80 ?g/L during the BAC stage at each plant. BAC exhaustion did not occur during the course of this study. Ozone-GAC reduced chlorine demand by 73% for the Aux Plant and 10% for the Main Plant.
Show less - Date Issued
- 2013
- Identifier
- CFE0004708, ucf:49824
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004708
- Title
- Integrating Spray Aeration and Granular Activated Carbon for Disinfection By-Product Control in a Potable Water System.
- Creator
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Rodriguez, Angela, Duranceau, Steven, Lee, Woo Hyoung, Sadmani, A H M Anwar, University of Central Florida
- Abstract / Description
-
Public water systems add disinfectants in water treatment to inactivate microbial pathogens. Chlorine, when used as a disinfectant, reacts with natural organic matter in the water to form trihalomethane (THM) and haloacetic acid (HAA5) disinfection by-products (DBPs), which are suspected carcinogens. The Safe Drinking Water Act's Disinfectant and Disinfection By-Product (D/DBP) Rules were promulgated by the U.S. Environmental Protection Agency to regulate the amount of DBPs in water systems....
Show morePublic water systems add disinfectants in water treatment to inactivate microbial pathogens. Chlorine, when used as a disinfectant, reacts with natural organic matter in the water to form trihalomethane (THM) and haloacetic acid (HAA5) disinfection by-products (DBPs), which are suspected carcinogens. The Safe Drinking Water Act's Disinfectant and Disinfection By-Product (D/DBP) Rules were promulgated by the U.S. Environmental Protection Agency to regulate the amount of DBPs in water systems. Regulatory compliance is based on maximum contaminant levels (MCL), measured as a locational running annual average (LRAA), for total THM (TTHM) and HAA5 of 80 (&)#181;g/L and 60 (&)#181;g/L, respectively. Regulated DBPs, if consumed in excess of EPA's MCL standard over many years, may increase chronic health risks. In order to comply with the D/DBP Rules, the County of Maui Department of Water Supply (DWS) adopted two DBP control technologies. A GridBee(&)#174; spray-aeration process was place into DWS's Lower Kula water system's Brooks ground storage tank in February of 2013. In March of 2015 the second DBP control technology, granular activated carbon (GAC), was integrated into DWS's Pi'iholo surface water treatment plant. To investigate the integration effectiveness of GAC and spray-aeration into a water system for DBP control, DBP data was gathered from the system between August of 2011 and August 2016, and analyzed relative to cost and performance.Prior to the spray aeration and GAC integration, it was found that TTHM levels at the LRAA compliance site ranged between 58.5 (&)#181;g/L and 125 (&)#181;g/L (at times exceeding the MCL). Additionally, HAA5 levels at the LRAA compliance site ranged between 21.2 and 52.0 (&)#181;g/L. The concerted efforts of the GAC and GridBee(&)#174; system was found to reduce LRAA TTHM and HAA5 concentrations to 38.5 (&)#181;g/L and 20.5 (&)#181;g/L, respectively, in the Lower Kula system. Hypothesis testing utilizing t-Tests confirmed that TTHMs levels were controlled by the spray aeration system and the GAC was responsible for controlling HAA5 formation. Although TTHM levels were reduced by 58 percent, and HAA5 levels by 48 percent, the estimated cumulative annual operation and maintenance (O(&)M) cost of the two systems was $1,036,000. In light of the cost analysis, total organic carbon (TOC)-based models for predicting LRAA TTHM and HAA5 levels were developed as equation (i) and (ii), respectively:(i) TTHM (&)#181;g/L = (32.5 x (TOC ppm)) + 5.59, (ii) HAA5 (&)#181;g/L = (8.37 x (TOC ppm)) + 12.4.The TTHM model yielded an R2 of 0.93, and the HAA5 model had an R2 of 0.52. F-Tests comparing predicted LRAA TTHM and HAA5 levels to actual LRAA TTHM and HAA5 levels determined no statistically-significant difference. With the knowledge of how the GAC and spray aerator controlled DBPs in the water system, a cost-effective and practical treatment operating parameter was developed. The parameter, Pi'iholo water plant filter effluent TOC content, can serve as an indicator that operators would use to alter DBP treatment process flow set points to achieve cost-effective treatment. Furthermore, the significant annual cost contribution by the GAC, coupled with HAA5 levels below DWS's MCLG, led to the recommendation of variable frequency drive (VFD) pumps for the GAC system. The addition of VFD pumps should reduce the frequency of carbon change outs while preserving adequate HAA5 control in the system.
Show less - Date Issued
- 2016
- Identifier
- CFE0006841, ucf:52881
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006841
