M.S.

Thesis advisor: Seth C. Kruckenberg / In the earth’s lithosphere there exists both homogeneous and heterogeneous deformation on a variety of scales. The lower crust specifically plays a critical role in lithospheric deformation; however, the lower crust does not deform homogenously but rather heterogeneously in space and time. One of the best avenues for addressing heterogeneous lower crustal deformation is through an integrated study of shear zones. While many studies have identified factors such as strain rate and temperature as key actors in lower crustal strain localization, more studies are needed to characterize the dominant grain-scale mechanisms that accommodate the development of lower crustal shear zones. The primary aim of this research is to investigate the dominant mechanisms that lead to strain localization in the lower crust. The Capricorn Ridge Shear Zone (CRSZ), Central Australia, is an ideal location for study because it is a lower crustal shear zone that contains discrete zones of strain localization, primarily adjacent to major lithological boundaries. Previous studies conclude that competency contrast caused strain to localize at the lithologic boundaries of the CRSZ, a hypothesis that is tested in this study. Using microstructural, textural, and rheologic analysis, as well as field-based mapping and grain size piezometry, this study finds that differential stresses in Capricorn Ridge range from 17-27 MPa for quartz, 31-42 MPa for plagioclase, and 2.8-7.6 MPa for enstatite. Monophase aggregate strain rates range from 1.6 x 10-15 to 1.7 x 10-14 s-1 for quartz, 4.5 x 10-15 to 3.3 x 10-14 s-1 for plagioclase, and 6.0 x 10-20 to 1.2 x 10-18 s-1 for enstatite; corresponding effective viscosities 0.3-1.7 x 1021 Pa.s, 0.3-1.5 x 1021 Pa.s, and 0.2-1.8 x 1025 Pa.s for quartz, plagioclase, and enstatite, respectively. Data across the CRSZ show that while strain rate (viscosity) in monophase aggregates of quartz and plagioclase are generally similar across the shear zone, they do decrease at lithologic boundaries. In contrast to a previous study’s finding that competency contrast caused strain to localize at these boundaries, both quartz and plagioclase appear to record strain accumulation through grain size reduction. However, the observations made in previous studies are not negated by this study, as it is possible that grain size reduction in the mylonite zones near the boundaries caused strain to accumulate over time and therefore produce the observed pattern of increasing fabric intensity with proximity to the lithologic boundaries. / Thesis (MS) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

[pt] O fato de que as bolhas ao atravessarem uma interface liquido-liquido podem aprender em seu entorno uma película, da fase inferior e conduzi-la através da fase superior, tem dado ensejo a vários trabalhos de pesquisa nesta Universidade. Neste, em particular se fez um estudo experimental da influência da tensão interfacial na quantidade de líquido transportado e na velocidade das bolhas transportadoras, quando a fase líquida superior tem viscosidade cinemática elevada. Usou-se para fase superior um líquido com viscosidade 60cS, composto de 15 por cento de Varsol e 85 por cento de Nujol. As tensões interfaciais 12,5 e 21,5 din/cm foram obtidas adicionando pequenas quantidades do agente tenso-ativo Teepol na água filtrada usada como fase inferior e que proporcionou a tensão interfacial 26,2 din/cm. Verificou-se que a tensão interfacial oi é de pouca relevância na quantidade de líquido transportado, e na velocidade terminal das bolhas transportadas, tendo entretanto grande influencia na faixa de diâmetros destas bolhas. A faixa das bolhas transportadas diminui com o aumento da tensão interfacial, e ambos os limites tendem a um valor intermediário, existindo uma tensão oi limite, a partir da qual o fenômeno de transporte de película deixa de ocorrer. / [en] The fact thjat bubbles passing through a liquid-liquid interface may acquire na enveloping layer, from the lower phase and carry it trough the upper phase hás provided na opportunity for many research Works at this UNiversity. In this particular work an experimental study of the influence of the interfacial tension on the quantity of liquid transported and on the speed of the rising bubbles was conducted for upper liquid phases with high kinematic viscosity. A liquid with a viscosity of 60cs, composed of 15 per cent Varsol and 85 per cent Nujol was uses as upper phase. Interfacial tensions of 12,5 and 21,5 din /cm were obtained by adding small quantities of the tense-active agente teepol in the filtered water which was used as the lower phase and which had an interfacial tension of 26,2 din/cm in the pure state. The interfacial tension was observed to exert a small influence on both the quantity of transported liquid and on the terminal velocity of transported liquid and on the terminal velocity of the rising bubbles. Llowever a great influence was found on the diameter range of these bubbles. The range of the transporting bubbles was found to decrease with increasing interfacial tension and both the upper and lower limits tend toward an intermediary value above which the transport phenomenon no longer exists.

This research will investigate techniques to create a sensor that is responsive to methane at 23°C. The approach will use the integration of a very thin film, which changes its resistive properties when methane gas is applied, deposited atop the surface of a piezoelectric substrate. An aluminum thin film interdigital transducer will launch a surface acoustic wave (SAW) that travels under the sensor’s gas-sensitive resistive thin film. The SAW/resistive film interaction changes the SAW amplitude, phase and delay. For this work, three films, tin dioxide (SnO2), zinc oxide (ZnO) and palladium (Pd) [1, 2] will be studied. Gas detection will be shown when combining ZnO and Pd, and, observable change in SAW propagation loss is measured when methane gas is present at the film.

<p> A series capillary viscometer has been used to measure the viscosity of nitrogen and air over a temperature range of 100 to 400°K and to pressures of 150 atmospheres. </p> <p>The low pressure results have been correlated using a modified Sutherland equation of the form: n = C1T^C2 / T+C3 </p> <p> Intermolecular force constants have been computed for nitrogen using the Chapman Enskog collision theory approach.</p> <p> The viscosity in the dense gas region was correlated using equations of the form n-no = A1ρ + A2ρ^2 and thus overall equations for viscosity as a function of temperature and density were formulated as n = C1T^C2 / T+C3 +A1ρ + A2ρ^2 </p> <p> These equations were used to generate tables of smoothed values of viscosity as a function of pressure and temperature.</p> / Thesis / Master of Engineering (MEngr)

The goal of this research is to measure viscosity via the analysis of amplitude response of a piezo driven vibrating cantilevers partially immersed in a viscous medium. As a driving frequency is applied to a piezoceramic material, the external forces acting on the system will affect its maximum amplitude. This thesis applies this principle through experimental and analytical analyses of the proportional relationship between viscosity and the amplitude response of the first natural frequency mode of the sinusoidal vibration. Currently, the few cantilever-based viscometer designs that exist employ resonant frequency response as the parameter by which the viscosity is correlated. The proposed piezoelectric viscometer employs amplitude response in lieu of resonant frequency response. The goal of this aspect of the research was to provide data confirming amplitude response as a viable method for determining viscosity. A miniature piezoelectric plate was mounted to a small stainless-steel cantilever beam. The tip of the cantilever was immersed within various fluid test samples. The cantilever was then swept through a range of frequencies in which the first frequency mode resided. The operating principle being as the viscosity of the fluid increases the amplitude response of cantilever vibration will decrease relatively. What was found was in fact an inversely exponential relationship between dynamic viscosity and the cantilever beam's vibrational amplitude response. The experiment was performed using three types of cantilevers as to experimentally test the sensitivity of each.

Existing viscosity prediction methods and relevant literature are reviewed. An exhaustive review of group contribution, corresponding states, and interpolative prediction methods finds that even the best of these models produces large prediction errors and often require significant experimental data. Molecular dynamics simulation techniques for viscosity prediction are evaluated and compared to one another to determine the best choice for this work. A thorough investigation finds that Equilibrium Molecular Dynamics (EMD) simulations are the best option for reproducible and reliable liquid viscosity predictions. The many tuning parameters available in molecular dynamics simulations are investigated for their effects on prediction uncertainty and accuracy. Challenges associated with molecular dynamics predictions are discussed and a rigorous simulation and data analysis methodology is developed which addresses these issues. The TLVMie force field is developed to describe linear alkanes, branched alkanes, alkylbenzenes, and cycloalkanes. The method is developed with a "training set" of compounds and the transferability is evaluated with a completely different "test set" of compounds. Predictive capability with mixture viscosities is evaluated next without any re-fitting of the parameters determined from pure-component data. The TLVMie potential is shown to be significantly more accurate for both pure-components and mixtures, more reliable for compounds that differ greatly from the training set, and predictions are made without the experimental data requirements of other methods.

What role do high and low wall shear stresses play in the deterioration of arteriole and capillary walls? Plaque buildup is common around bifurcations in arterioles, indicating that low wall shear stress may play a role in the weakening of the walls. This thesis investigates the creation of blood analog fluid used in a Polydimethylsiloxane (PDMS) curved channel to explore the fluid properties and characteristics near bifurcations. Major results in the experiments showed the viscosity and surface tension trends of a blood analog fluid composed of xanthan gum, glycerin, and distilled water with the addition of Silver Coated Hollow Glass Spheres in varying volume fractions. All experiments were conducted at room temperature with varying flow rates between 0.1-2 µL/second. The velocity profile was characterized at each flow rate. Important results that will be discussed will include the variation of flow near bifurcations and at different flow rates and RBC concentration. Full parabolic velocity profiles formed in the straight region of the channels as expected. After the bifurcation, the velocity profile was skewed to the outer wall. At lower flow rates there were fewer particles flowing near the wall of the channel.

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