Current Search: Reddi, Lakshmi (x)
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- Title
- PREDICTIVE MODELING OF SULFIDE REMOVAL IN TRAY AERATORS.
- Creator
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Faborode, Jumoke, Reddi, Lakshmi, University of Central Florida
- Abstract / Description
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Hydrogen sulfide is commonly found in many Florida potable groundwater supplies. Removing sulfur species, particularly hydrogen sulfide is important because if left untreated, sulfide can impact finished water quality, corrosivity, create undesirable taste and odor, and oxidize to form visible turbidity and color. This document presents the results of a study designed to investigate the removal efficiencies of a variety of tray aerators in Central Florida in order to develop a predictive...
Show moreHydrogen sulfide is commonly found in many Florida potable groundwater supplies. Removing sulfur species, particularly hydrogen sulfide is important because if left untreated, sulfide can impact finished water quality, corrosivity, create undesirable taste and odor, and oxidize to form visible turbidity and color. This document presents the results of a study designed to investigate the removal efficiencies of a variety of tray aerators in Central Florida in order to develop a predictive mathematical model that could be used to determine tray effectiveness for sulfide removal. A literature review was performed that indicated there was limited information regarding the removal of hydrogen sulfide using conventional tray aerators, and no information regarding the removal of total sulfide from tray aerators. There was significantly more information available in the literature regarding the usefulness of sulfide removal technologies from water supplies. Consequently, the lack of literature regarding sulfide removal using tray aerators suggested that there was a need for additional research focused on sulfide removal from water flowing thru tray aerators. Several water purveyors that relied on tray aerators as a part of their water treatment operations were contacted and requested to participate in the study; three water purveyors agreed to allow the University of Central Florida (UCF) to enter their secured sites to collect samples and conduct this study. The three facilities included the UCFÃÂ's water treatment plant located in Orlando and situated in eastern Orange County, the City of Lake HamiltonÃÂ's water treatment plant located in west-central Polk County, and the Sarasota-Verna water treatment plant located in western Sarasota County. An experimental plan was developed and field sampling protocols were implemented to evaluate sulfide removal in commonly used tray aerators at the three drinking water treatment facilities. Total sulfide concentrations passing through the trays were determined in the field at each site using a standard iodometric analytical technique. In addition, other water quality parameters collected included dissolved oxygen, pH, temperature, conductivity, turbidity, alkalinity, hardness, total dissolved solids and total suspended solids; these samples were collected and analyzed either in the field or at the UCF laboratory. A first-order empirical model was developed that predicted sulfide removal in tray aerators. The modelÃÂ's constant was evaluated with respect to the waterÃÂ's proton concentration , the tray aeratorÃÂ's surface area, and hydraulic flow rate thru the trays. The selected model took the form of Cn=C0 (10-kn) where Cn is the sulfide remaining after aeration in mg/L, C0 is the sulfide entering the distribution tray in mg/L, n is the number of tray stages in the aerator, and k=(0.00248)(H^+ )^(-0.397) (Area)^0.584 (Flow)^(-1.17). From the empirical model, it was shown that sulfide removal was negatively impacted as the proton concentration (H+) decreased, and flow increased. Conversely, it was observed that increased sulfide removal occurred as the available tray aerator surface area increased. The combined parameters of proton concentration, flow rate, and area were statistically evaluated and used to develop an empirical constant that could be used in a first order model to predict sulfide removal in tray aerators. Using a site-specific derived experimental (empirical) constant, a water purveyor could use the developed model from this work to accurately predict sulfide removal in a tray aerator by simply measuring the total sulfide content in any raw groundwater supply and then providing the desired number of tray stages available for treatment.
Show less - Date Issued
- 2010
- Identifier
- CFE0003518, ucf:48980
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003518
- Title
- FINITE DEPTH SEEPAGE BELOW FLAT APRON WITH END CUTOFFS AND A DOWNSTREAM STEP.
- Creator
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Jain, Arun, Reddi, Lakshmi, University of Central Florida
- Abstract / Description
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Hydraulic structures with water level differences between upstream and downstream are subjected to seepage in foundation soils. Two sources of weakness are to be guarded against: (1) percolation or seepage may cause under-mining, resulting in the collapse of the whole structure, and (2) the floor of the apron may be forced upwards, owing to the upward pressure of water seeping through pervious soil under the structure. Many earlier failures of hydraulic structures have been reported due to...
Show moreHydraulic structures with water level differences between upstream and downstream are subjected to seepage in foundation soils. Two sources of weakness are to be guarded against: (1) percolation or seepage may cause under-mining, resulting in the collapse of the whole structure, and (2) the floor of the apron may be forced upwards, owing to the upward pressure of water seeping through pervious soil under the structure. Many earlier failures of hydraulic structures have been reported due to these two reasons. The curves and charts prepared by Khosla, Bose, and Taylor still form the basis for the determination of uplift pressure and exit gradient for weir apron founded on pervious soil of infinite depth. However, in actual practice, the pervious medium may be of finite depth owing to the occurrence of a clay seam or hard strata at shallow depths in the river basin. Also, a general case of weir profile may consist of cutoffs, at the two ends of the weir apron. In addition to the cutoffs, pervious aprons are also provided at the downstream end in the form of (i) inverted filter, and (ii) launching apron. These pervious aprons may have a thickness of 2 ft. to 5 ft. In order to accommodate this thickness, the bed adjacent to the downstream side of downstream cutoff has to be excavated. This gives rise to the formation of step at the downstream end. Closed form theoretical solutions for the case of finite depth seepage below weir aprons with end cutoffs, with a step at the downstream side are obtained in this research. The parameters studied are : (i) finite depth of pervious medium, (ii) two cut offs at the ends, and (iii) a step at the downstream end. The resulting implicit equations, containing elliptic integrals of first and third kind, have been used to obtain various seepage characteristics. The results have been compared with existing solutions for some known boundary conditions. Design curves for uplift pressure at key points, exit gradient factor and seepage discharge factor have been presented in terms of non-dimensional floor profile ratios.
Show less - Date Issued
- 2011
- Identifier
- CFE0003898, ucf:48751
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003898
- Title
- Biomechanics of Developmental Dysplasia of the Hip - An engineering study of closed reduction utilizing the Pavlik harness for a range of subtle to severe dislocations in infants.
- Creator
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Huayamave, Victor, Divo, Eduardo, Kassab, Alain, Reddi, Lakshmi, University of Central Florida
- Abstract / Description
-
Developmental Dysplasia of the Hip (DDH) is an abnormal condition where hip joint dislocation, misalignment, or instability is present in infants. Rates of incidence of DDH in newborn infants have been reported to vary between 1 and 20 per 1000 births, making it the most common congenital malformation of the musculoskeletal system. DDH early detection and treatment is critical to avoid the use of surgical treatment in infants and to prevent future complications such as osteoarthritis in adult...
Show moreDevelopmental Dysplasia of the Hip (DDH) is an abnormal condition where hip joint dislocation, misalignment, or instability is present in infants. Rates of incidence of DDH in newborn infants have been reported to vary between 1 and 20 per 1000 births, making it the most common congenital malformation of the musculoskeletal system. DDH early detection and treatment is critical to avoid the use of surgical treatment in infants and to prevent future complications such as osteoarthritis in adult life. To this day several non-surgical treatments involving the use of harnesses and braces have been proposed to treat DDH in infants, with the Pavlik harness being the current non-surgical standard used to treat DDH at early stages. Although the Pavlik harness has been proven to be successful treating subtle dislocations, severe dislocations do not always reduce. Until now the use of the harness remains an empirical method, and its effectiveness often depends on physician expertise or trial-error procedures; thus a clear guideline has not been established to determine the best optimal harness configuration to treat both subtle and severe dislocations. The goal of this dissertation is to understand the connection between reductions for subtle and severe dislocations and passive muscle forces and moments generated while the harness is used during treatment. While the understanding of DDH biomechanics will provide a valuable clinically applicable approach to optimize and increase harness success rate, it is not without its difficulties. This research has created and developed a three-dimensional based on patient-specific geometry of an infant lower limb. The kinematics and dynamics of the lower limb were defined by modeling the hip, femur, tibia, fibula, ankle, foot, and toe bones. The lines of action of five (5) adductor muscles, namely, the Adductor Brevis, Adductor Longus, Adductor Magnus, Pectineus, and Gracilis were identified as mediators of reduction and its mechanical behavior was characterized using a passive response. Four grades (1-4) of dislocation as specified by the International Hip Dysplasia Institute (IHDI) were considered, and the computer model was computationally manipulated to represent physiological dislocations. To account for proper harness modeling, the femur was restrained to move in an envelope consistent with its constraints. The model of the infant lower limb has been used to analyze subtle and severe dislocations. Results are consistent with previous studies based on a simplified anatomically-consistent synthetic model and clinical reports of very low success of the Pavlik harness for severe dislocations. Furthermore the findings on this work suggest that for severe dislocations, the use of the harness could be optimized to achieve hyperflexion of the lower limb leading to successful reduction for cases where the harness fails.This approach provides three main advantages and innovations: 1) the used of patient-specific geometry to elucidate the biomechanics of DDH; 2) the ability to computationally dislocate the model to represent dislocation severity; and 3) the quantification of external forces needed to accomplish reduction for severe dislocations. This study aims to offer a practical solution to effective treatment that draws from engineering expertise and modeling capabilities and also draws upon medical input. The findings of this work will lay the foundation for future optimization of non-surgical methods critical for the treatment of DDH.
Show less - Date Issued
- 2015
- Identifier
- CFE0005631, ucf:50216
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005631