Spacecraft are vulnerable to hypervelocity impacts (HVIs) from micrometeoroid/orbital debris (MMOD) while in space and must mitigate these using shielding. In this research aluminum honeycomb core sandwich panels filled with a shear thickening fluid (STF) were developed as a novel MMOD shielding concept. STFs display a marked rise in viscosity with increasing shear rate above a critical shear rate. The results of HVI experiments with impact velocities of ~4.8 km/s or ~6.8 km/s at 80oC or 21oC showed that incorporating a STF into shielding, as opposed to the STF’s liquid phase alone, can reduce damage to the core and the likelihood of back-side facesheet perforation in the event of HVI. STFs can be subjected to a significant temperature variation in many applications such as the HVI experiments in this research or when deployed on the surface of a spacecraft. The effect of temperature on the shear-thickening behavior was investigated using four low molecular weight polymeric glycols/fumed-silica suspensions. The dispersed phase volumeraction, its surface chemistry, and the chemical compositions of the suspending media were varied in a series of steady shear rheological characterizations over a range of temperatures. It was thought that hydroclustering mechanism initiated the onset of shear thickening, and this onset was shown to be more closely correlated to a critical shear rate rather than a critical shear stress. Evidence of the hydroclustering mechanism was sought using small angle neutron scattering (SANS) experiments. SANS steady state rheological characterization experiments were carried out on five low molecular weight polymeric glycols/fumed-silica STFs at the NIST Center for Neutron Research. The SANS experiments were conducted at shear rates below the critical shear rates, at the critical shear rates, and during shear thickening. In all the SANS experiments, the results showed an increase in scattering intensity with increasing shear rates indicating an evolution of the suspension microstructure consistent with the formation of hydroclusters.

In this work, fatigue experiments and observations are used to experimentally and computationally quantify fatigue structure-property relationships and then capture these effects through a microstructure-based MultiStage Fatigue (MSF) model for a thermoplastic Acrylonitrile Butadiene Styrene copolymer. Completely reversed fatigue experiments were conducted over a range of strain amplitudes at two frequencies (1 Hz and 10 Hz). Scanning electron microscopy of fatigue fracture surfaces was used to quantify the microstructural notch root or initiating particle size for structure-property relations. Results were then processed in an MSF model sensitive to microstructural effects to capture the fatigue lifetimes for the thermoplastic ABS copolymer.

<p>  </p> <p>Dehydrogenation is a common reaction used to upgrade paraffins to olefins in the chemical and oil industries. Given the increased abundance of inexpensive alkanes due to the worldwide shale gas boom, this reaction has become increasingly important. Conventional industrial techniques such as thermal cracking and steam cracking have relatively poor olefin selectivity and thus require energy-intensive separations. Industry is increasingly relying on catalytic dehydrogenation as a more environmentally friendly alternative to generate olefins. While recent development in catalyst materials has largely solved issues with activity and selectivity, issues with catalyst stability remain. Deactivation mechanisms such as coke formation and phase changes plague the short-term and long-term stability of these catalysts, often requiring frequent and intensive regeneration procedures. </p> <p>This thesis will explore several strategies for mitigating the deactivation of dehydrogenation catalysts. This includes the modification of catalyst properties and reaction conditions, such as the catalyst support and the use of H2, to mitigate coke formation and even regenerate catalyst materials non-oxidatively, thus increasing the catalyst lifetime. Secondly, this thesis will cover the discovery of new catalyst materials through computational predictions based on descriptors assessed from several previous works. Experimental validation of these predictions led to the discovery of several new Rh and Ir based alloy materials that are remarkably selective and stable for propane dehydrogenation (PDH). Lastly, the contribution of electronic structure of PDH catalysts will be assessed using a new characterization technique that will help relate catalyst properties to catalyst performance and stability. </p> <p>Several advanced X-ray synchrotron techniques have assisted the analysis and discovery of catalyst materials in this work. Particularly, this includes difference-EXAFS to assess the surface structure of alloy catalyst materials as well as the newly-developed non-resonant X-ray emission spectroscopy (NR-XES) to assess the electronic structure of the 5d valence band for Pt catalyst materials. To extend this work further, the goal is to apply this new technique to additional catalyst materials, such as Pt alloys or single site Pt supported on CeOx, in order to measure the effect of different adsorbates on the electronic structure of the Pt catalyst. This will help derive fundamental insights to drive the development of the next generation of stable dehydrogenation catalyst materials.  </p>

The Thrace Basin, NW Turkey, is one of the most important basins in Turkey in terms of hydrocarbon potential. Previous studies, starting in the 1930s, focused on tectonics, basin evolution, sedimentation and stratigraphy, depositional systems, and hydrocarbon potential. Eocene turbiditic sandstones and reefal limestones, and Oligocene deltaic sandstones are the major reservoir targets in the basin today. The focus of this research is the Upper Oligocene deltaic sandstones, namely the Danismen and Osmancik formations, which contain potential hydrocarbon reservoirs. The aims of research were to develop a better understanding of the geometric configuration of the Oligocene strata and to identify potential reservoirs within the study area. Accordingly, the geometric configurations of the strata were delineated using 3D seismic reflection data whereas petro-physical properties of the target formations were determined using wireline logs from three wells. A right-lateral strike slip or reverse fault system and associated NW-SE trending asymmetric fold extend across the study area. Both the fault system and the fold are truncated beneath the Miocene unconformity and are thus dated as late Oligocene to early Miocene in age. The Miocene unconformity forms a stratigraphic trap whereas the fault system and associated fold construct a NW-SE trending structural trap. Hydrocarbon-bearing, five main clean sandstone (shale volume less than %10) intervals were identified using wireline logs and evaluated as potential targets. Hydrocarbon concentrations increase through the fold structure. Thus, the fault system and the associated asymmetric fold were the main factors that affected the zonal distribution of hydrocarbons in the study area. / Master of Science

Disease identification is one of the most important aspects of a physician's duties. Radiologists play a very important role in disease recognition based on the increasing use of diagnostic images. Nowadays, medical scanning devices such as MRI and CT produce thousands of images per patient which makes the radiologist's job even more onerous; indeed radiologists look at approximately 50,000 images per day leading to fatigue and a higher probability for missing smaller lesions. Therefore it is critical to assist radiologists in their duties.In this PhD work, research is focused on developing segmentation-based mathematical algorithms and computer programs for automatically characterizing lung CT images. There are two kinds of segmentation methods; the first group contains the methods that find edges of all objects in the image and the second group contains the methods that focus on one object in the image. By assessing many segmentation methods and based on the concept of this project, the level set method, from the second group, has the capability to accurately find the boundary of an object in medical images. Although this method does not need any threshold for segmenting an object in an image, it does require the setting of seven parameters. Genetic algorithms were employed to optimize seven parameters of the level set method for use as a boundary detection method. A streamlined automatic mechanism, essential for successful and fast segmenting processes, provided the level set method with a good initial contour.This segmentation step was fundamental for further measurements such as bronchial lumen diameter and wall thickness measurement. The developed program automatically measures airway lumen diameter with exceptional repeatability. Also, by simulating manual methods used by radiologists for measuring luminal wall thickness, the automated fitting method consistently finds the wall thickness at the thinnest part, minimizing partial volume problems. The current standard for measuring luminal wall thickness is the full-width at half-maximum method. The technique formulated here is more accurate and reproducible and can be performed automatically. To find the lumen airway tapering, in order to recognize some prominent lung diseases, a method for tracing of an airway through various CT slices was developed. These measurements are of critical importance in the understanding of a number of lung diseases including asthma and COPD; this tracing step was fundamental for bronchial bifurcation angle measurement. This tracing method was extended to detect and follow bifurcation branches. Then, an estimation method for finding a fitted line through airway center points was developed. For the last portion of this PhD work an approach for measuring lung airway bifurcation angle from CT datasets, which is important in lung diseases such as asthma, was created. The current goal, characterizing lung CT images, was achieved as a working form of this software development. This mathematical approach has been shown to be accurate with phantom studies. The ultimate goal of this work was to develop software for recognizing key lung diseases and to compare serially (weeks or months apart) acquired images to assess any progress, regression, or stability in a disease. / Thesis / Doctor of Philosophy (PhD)

<p> Water soluble polymers are used as flocculants in wastewater treatment, mineral processing, and pulp and paper production. The work in this thesis focuses on the synthesis of graft polyelectrolytes and the efficiency of the copolymers in flocculation. It was proposed that it would be advantageous to have clusters of high charge that can adsorb strongly to the particle surface, and a long chain of nonionic polymer to bridge the particles together.</p> <p> Electrolyte copolymers were produced using a high molecular weight polyacrylamide as the backbone polymer and a redox agent, ceric ammonium nitrate, to form a radical site on the polymer. DADMAC monomer was polymerized from these radical sites producing grafts of cationic charge. The copolymers were produced at a range of polymerization conditions including PAM concentration, amount of nitric acid, amount of ceric ion and polymerization temperature. Grafting was successful and homopolymerization of DADMAC was found not to occur. The graft polymers were characterized using NMR, charge titration, viscosity measurements, and gel fraction measurements.</p> <p> The copolymers were tested for flocculating properties using a model TiO2 system. The graft copolymers produced performed better than the backbone polyacrylamide, low and high molecular weigh polyDADMAC, and a commercial random copolymer of acrylamide and DADMAC. It was found that both the amount of charge and gel is very important in flocculation performance. However, the testing of the copolymers as a conditioner for a municipal sludge did not show improvement in the drainage rate.</p> / Thesis / Master of Engineering (MEngr)

<p> Temperature sensitive microgel latexes of poly (N-isopropylacrylamide) cross-linked with N-N'methylene bisacrylamide (BA) were prepared and characterized by Dynamic Light Scattering, Titration and Electrophoresis. The study of gels, including temperature sensitive gels, is limited by the large size of traditional bulk gels which are slow to respond to changes and are difficult to measure. An alternative system, which may be easier to study, is a microgel latex which would constitute small particles of gel which would respond quickly to changes in their environment and could also be measured using colloidal measuring techniques like dynamic light scattering and particle electrophoresis.</p> <p> Monodisperse and stable microgel latex particles were prepared by reacting Nisopropylacrylamide (NIPAM) monomer with a cross-linking agent BA in water at 70°C with a surfactant (sodium dodecylsulfate) present. Latexes prepared without surfactant were polydisperse.</p> <p> Characterization of the poly (NIPAM) particles by dynamic light scattering at several different temperatures showed that the particles go through a transition from a water swollen gel at low temperature to a shrunken gel with a low water content at high temperature. The transition occurs about 32°C. The degree of swelling of the poly (NIPAM) particles can be expressed by the Flory-Huggins Interaction parameter c and is dependent upon the level of cross-linking agent included.</p> <p> Titration and electrophoresis results indicate that the particles contain about 0.39 Coulombs per gram of polymer of carboxylic and sulfuric charged end groups which are distributed throughout the particle.</p> / Thesis / Master of Engineering (MEngr)

<p> The wastewater from a freshwater fish processing plant was characterized. The plant processed perch and smelt, and thus the wastewater characterized was taken from the perch and smelt processing lines and a combined perch and smelt wastewater. The plant also manufactured fish meal from the fish offal. During this process the offal is pressed to obtain stickliquor. Since this stickliquor is a potential waste product it too was characterized.</p> <p> It was concluded that the wastewater was either of medium strength with large flows or of high strength with low flows.</p> <p> Batch and continuous reactor studies were undertaken to ascertain the degradability of the combined wastewater. It was determined that a reactor with either a detention in excess of 5 days with no sludge recycle or a short detention time reactor (7.5 hours) with sludge recycle would be necessary to effect maximum removal of total BOD5.</p> <p> The effect of physical treatment, flotation, sedimentation and in-plant screening, were also examined in a preliminary manner.</p> / Thesis / Master of Engineering (MEngr)

This thesis presents a literary study of three subtypes of the maiden stock character in Plautine Comedy: the silent virgo, the meretrix-virgo, and the virgo in transition. The comic maiden is remarkable in Roman Comedy, in that she is the female protagonist of most if not all of the plays in which she is a character, although she sometimes never appears onstage. The aim of this thesis is to investigate how the playwright manages and enrichens his portrayals of the virgo despite her limitations, and to analyze her significance in the broader themes of her plays. This has been done by detailed character analyses of three of Plautus’ plays, each of which features a virgo who represents one of the three subtypes of the comic maiden (i.e. Phaedria from Plautus’ Aulularia, Palaestra from Plautus’ Rudens, and Alcmena from Plautus’ Amphitruo respectively). Through the examination of the characters’ speeches and conversations, including those presented by the maiden herself when she appears onstage, it is evident that the virgo is a central figure in tensions and conclusions driving the plot. Because of her contradictory circumstances (i.e. her premarital pregnancy, slave status, or change in stock role), this integral function is contingent on her piety and innocence, which must be maintained throughout the play. Finally, the propitious resolution of the plot comes about in the restoration of the maiden’s status and the promise of marriage between her and the male lover. Because of this, she is also deeply connected to the underlying themes of morality and communal bonds governing the play. This research highlights the valuable and central role of a character in Plautine comedy, whose on-stage presence is often limited or even non-existent. / Thesis / Master of Arts (MA) / This thesis analyzes the portrayals of three subtypes of the virgo or maiden stock character in the comedies of Plautus, a Roman playwright who flourished in the late third to early second centuries BCE. More specifically, this thesis presents a detailed character study of Phaedria as the silent maiden in Aulularia, Palaestra as the prostitute-maiden (meretrix-virgo) in Rudens, and Alcmena the maiden in transition in Amphitruo. The aim is to investigate how Plautus manages and enrichens his characterization of these maidens, as well as their significance in the broader themes of the plays. Through the textual analyses of characters’ speeches and dialogues, this research highlights the centrality of the virgo in the tensions and resolutions driving the plot, and her connection to the underlying themes of morality and communal bonds in Plautus’ plays.

<p dir="ltr">Reaction zone thickness directly affects detonation properties such as detonation velocity and critical diameter. It is hypothesized that the effective reaction zone thickness is influenced by the particle size distribution and solids loading (wt.%) (solids loading) of an explosive material. In this study, we test several paste extrudable explosive (PEX) samples, to study the effects that varying particle size distribution and solids loading have on detonation properties. The PEX samples are based on four different explosives (RDX, PETN, HMX and DAAF), created by suspending explosive particles of different size distributions within an inert binder. A novel half- cone geometry is used to test the samples allowing for the capture of detonation speed (using a high-speed camera) and failure thickness data, by using the polycarbonate half-cone as a witness plate. Using this data, we create a diameter effect curve for each of the samples, allowing us to indirectly compare relative reaction zone thicknesses by measuring the slope of the linear region of the plots. Data found in open literature was compared to the PEX samples used in this study, but data was scarce. This study hopes to narrow the gap found in open literature.</p>