Search results

Title: Experimental photoelastic strain measurements and numerical simulations on multi-material Pi-/T- joints
Creator: Khawarizmi, Ryan
Date: 2018
Collection: Electronic Theses & Dissertations
Description: An adhesively bonded Pi-/T-joint is a common ‘out-of-plane’ structural joint that connects a vertical (web) and a horizontal (base) load bearing substrates using an adhesive and a 3D-braided π (pi) preform. The stress-transfer between the substrates and the preform occurs through the adhesive bond-line via complex mechanisms that are governed by the loading condition and material properties of the substrates and the adhesive. Resistance strain gages and fiber optic sensors can only provide...
Show moreAn adhesively bonded Pi-/T-joint is a common ‘out-of-plane’ structural joint that connects a vertical (web) and a horizontal (base) load bearing substrates using an adhesive and a 3D-braided π (pi) preform. The stress-transfer between the substrates and the preform occurs through the adhesive bond-line via complex mechanisms that are governed by the loading condition and material properties of the substrates and the adhesive. Resistance strain gages and fiber optic sensors can only provide local/single-point measurement. Moreover, embedding them in the adhesive bond-line is impractical as they act as stress-concentrators and sites for the onset of failure. Optical techniques, especially the photoelasticity coating method, enables the full-field visualization of stress/strain fields. In this work, the Pi-/T-joints were made with aluminum substrates (both web and base) and a carbon fiber pi-preform using SC-15 resin as an adhesive. The joints were manufactured using the liquid resin transfer molding technique. The photoelasticity coating method was used to visualize and measure plane strains and stress directly on the joint using polarized light. The joints were experimentally tested in ‘out-of-plane’ (web pull-out) configuration until failure, and the isochromatic photoelasticity fringes or strain field images from the surface of the specimen were recorded. Force-displacement data were also characterized. Numerical models were developed using commercially available software ABAQUS®. Results show reasonably good agreement between the strain maps from photoelasticity and numerical simulations for similar load levels. Improvements in technique and modeling are suggested in order to improve agreement and to gain added insight into the complex behavior of these joints.
Show less

Title: Olfaction impairment and its association with weight and progressive weight loss in older adults
Creator: Purdy, Frank Daniel
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Olfaction impairment (OI) is a very common, but underreported, sensory deficiency among older adults that can lead to a host of adverse health conditions, quality of life issues, and is a predictor of 5-year mortality. Similarly, body composition and weight are driving factors of poor health among older populations, with malign effects including decreased mobility and sarcopenia. We theorize that older adults with OI both weigh less, and lose weight faster than those with without any...
Show moreOlfaction impairment (OI) is a very common, but underreported, sensory deficiency among older adults that can lead to a host of adverse health conditions, quality of life issues, and is a predictor of 5-year mortality. Similarly, body composition and weight are driving factors of poor health among older populations, with malign effects including decreased mobility and sarcopenia. We theorize that older adults with OI both weigh less, and lose weight faster than those with without any impairment. Our goal is to examine how OI associated with weight and weight loss two ways: 1) cross-sectional, where we assess the association during the year sense of smell was tested; and 2) longitudinally, where we inspect whether OI indicates more rapid weight loss over a seven-year period. The outcome variables of interest were total mass, total lean mass, total bone-free lean mass and total fat mass. Analyses were also performed in race-specific populations and in sex-specific populations. Data were obtained from the Health, Aging and Body Composition Study. The study found in the cross-sectional analysis that those with poor olfaction has significantly less total mass (-1.48 kg) and fat mass (-1.05 kg) than those with good olfaction. Longitudinally, those with poor olfaction showed a significantly faster decrease in total mass (-245.7 g/year), lean mass (-171.4 g/year) and bone free mass (-164.7 g/year) but not fat mass. Differing results were found in race-specific analyses but not in sex-specific analyses, with the decrease in weight appearing in whites but not blacks.
Show less

Title: Aerobic bacterial gingival flora of the dog
Creator: Saphir, Dennis Armin
Date: 1975
Collection: Electronic Theses & Dissertations

Title: Membrane filtration of crude oil emulsions stabilized by Corexit 9500 dispersant
Creator: Kucuk, Seyma
Date: 2018
Collection: Electronic Theses & Dissertations
Description: During the 2010 Deepwater Horizon oil spill, nearly 800 million liters of oil were released into the Gulf of Mexico polluting the deep ocean and more than 1600 km of the Gulf’s shoreline. A large amount (7 million liters) of oil dispersant, Corexit EC 9500A, was applied to the spill; as a result, the oil was emulsified into microdroplets that remained suspended in the water column. Even though small droplets biodegrade faster, they can pose significant environmental risks. Microfiltration is...
Show moreDuring the 2010 Deepwater Horizon oil spill, nearly 800 million liters of oil were released into the Gulf of Mexico polluting the deep ocean and more than 1600 km of the Gulf’s shoreline. A large amount (7 million liters) of oil dispersant, Corexit EC 9500A, was applied to the spill; as a result, the oil was emulsified into microdroplets that remained suspended in the water column. Even though small droplets biodegrade faster, they can pose significant environmental risks. Microfiltration is the one of the most cost-effective remediation technologies that can remove emulsified oil. The present work is the first study of membrane filtration of Corexit-stabilized crude oil emulsions where properties and filterability of the emulsions in aqueous solutions of different salinities are evaluated. Salinity of the continuous phase was altered by adding MgSO4, NaCl, or a synthetic sea salt mixture. Emulsions were characterized in terms of their droplet size distribution, interfacial tension, and zeta potential. Corexit altered both emulsion stability and the wetting properties of the membranes. Emulsion characterization and constant pressure stirred dead-end filtration tests revealed that salinity affects the stability of emulsions and can enhance microfiltration performance. Almost compete rejection of oil was achieved but was accompanied by a precipitous flux decline. The low values of the steady state permeate flux indicate that microfiltration is suitable as a polishing step that follows an extensive pretreatment by large throughput deoiling unit processes such as hydrocyclonic separation or flotation.
Show less

Title: The synthesis and characterization of some n-substituted cyclosiloxazanes and cyclodisilazanes
Creator: Swihart, Terence John
Date: 1969
Collection: Electronic Theses & Dissertations

Title: Shakespeare and Melville's Moby-Dick
Creator: Switzer, Charles Irvin
Date: 1956
Collection: Electronic Theses & Dissertations

Title: Adult role-playing responses to varying child communications
Creator: Teyber, Edward Charles, 1950-
Date: 1975
Collection: Electronic Theses & Dissertations

Title: Modern innovations in musical notation for stringed instruments
Creator: Snyder, John LeRoy
Date: 1974
Collection: Electronic Theses & Dissertations

Title: A comparison of some personality aspects of delinquent and non-delinquent boys by means of a sentence completion technique
Creator: Thelen, Mark Herman
Date: 1959
Collection: Electronic Theses & Dissertations

Title: Comparing change in neural indices of attentional bias and cognitive control between cognitive behavioral therapy and attention bias modification for social anxiety disorder
Creator: Louis, Courtney C.
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "Cognitive models of Social Anxiety Disorder (SAD) state that an imbalance between attention bias (AB) and cognitive control (CC) maintain anxious symptoms. Event-related potentials (ERPs) serve as a precise index to assess these processes. The current study aimed to examine change in the P1 and N2 as indices of AB and CC within Cognitive Behavioral Therapy (CBT) and Attention Bias Modification (ABM) in individuals diagnosed with SAD. There were two primary aims -- (1) to examine change in...
Show more"Cognitive models of Social Anxiety Disorder (SAD) state that an imbalance between attention bias (AB) and cognitive control (CC) maintain anxious symptoms. Event-related potentials (ERPs) serve as a precise index to assess these processes. The current study aimed to examine change in the P1 and N2 as indices of AB and CC within Cognitive Behavioral Therapy (CBT) and Attention Bias Modification (ABM) in individuals diagnosed with SAD. There were two primary aims -- (1) to examine change in the P1 and N2 to the faces and probe in the dot probe task, and (2) to examine whether changes in ERPs predict symptom change. The sample consisted of 50 adult patients diagnosed with SAD, who were randomly assigned to CBT (n = 33) or ABM (n = 17). For the first aim, multi-level models (MLM) were used to estimate growth curves for each ERP. The results revealed an increase in the N2 to the faces over time for both groups (b = -.38, p = .02) at post-treatment. No other ERP changes reached significance (all p's > .09). For the second aim, individual growth slopes of ERPs and symptoms were correlated with each other, however there were no relationships between ERPs and symptom change (all p's > .40). Lagged MLMs with ERPs as predictors of symptoms demonstrated that a smaller N2 at one assessment related to more avoidance symptoms at the next assessment for the ABM group only (b = -1.23, p = .02). These results signify the need for reliable methods to assess AB, as well as increased specificity of CC processes that are targeted and exercised within treatment contexts."--Page ii.
Show less