Master of Science, University of Toledo, 2017, Civil Engineering

Heat exchanger piles are the thermo-active foundation system that can be used to extract geothermal energy for heating and cooling in the supported upper structures. Geothermal energy is a renewable, clean, efficient and cost-effective source of energy. The temperature below the Earth's surface remains relatively constant throughout the year but varies spatially with the earth depth. Piles are typically used as a main component of engineering structures, transferring the load from an upper structure to the supporting geological formation when necessary. The temperature gradient can be utilized by facilitating a circulating fluid inside the pile which can extract heat from the ground as well as release the heat to the ground during winter and summer seasons, respectively. As such these so-called heat exchange piles serve as both a structural component as well as a heat exchanging component. The main objective of this thesis is to numerically study the behavior of heat exchanger piles and surrounding soils under different scenarios. Different combinations of thermal, mechanical and hydraulic loadings were applied during the simulation of the heat exchanger pile using a finite element program, Code_Bright. Mechanical responses of the heat exchange pile were examined, along with the thermal and mechanical responses of soils. Some hydraulic scenarios were also explored. First, numerical simulations were carried out under the mechanical loading only, focusing on the thermo-mechanical behavior of heat exchanger pile. The mechanical properties of the pile were examined and the compressive stress was found to be maximum at the pile head and decrease along the pile depth during the application of the pure mechanical loading; whereas during the application of thermal loading with the mechanical loading, the compressive stress was found to be maximum around the mid-depth of the pile with minimum values at the ends. The point of maximum stress, referred as the point of inve (open full item for complete abstract)

Committee: Liangbo Hu (Committee Chair); Brian W. Randolph (Committee Member); Eddie Y. Chou (Committee Member) Subjects: Civil Engineering; Energy; Engineering; Geotechnology

Master of Science (M.S.), University of Dayton, 2024, Mechanical Engineering

The next generation of aircraft requires novel structural designs capable of enduring extreme multiphysics environments. Multiscale topology optimization – where macroscale properties and mesoscale topology are either concurrently or sequentially optimized – provides a compelling framework for addressing this complex structural design problem. In the sequential scheme utilized herein, targeted thermo-mechanical properties specified by a macroscale optimization are subsequently matched with a mesoscale unit cell topology and corresponding homogenized properties from a mesoscale optimization. Although this sequential approach provides greater design flexibility than its concurrent counterparts, a key drawback is significant computational expense. To mitigate this expense, this thesis introduces two novel and efficient mesostructure selection approaches, both predicated on jettisoning the computationally expensive mesoscale optimization. In its place, the proposed methods select – from a series of pre-existing designs generated prior to the macroscale optimization (thus adding no computational time) – the unit cell topology that best matches the targeted thermo-mechanical properites of the voxel. Our framework is first applied to a thermo-mechanically loaded Messerschmitt-Bolkow-Blohm beam, with the resulting designs exhibiting a compliance within 1% and a resistivity within 4% of the optimized solution, while simultaneously reducing computational burden from months to minutes. This framework is then applied to a thermally loaded bi-material ring problem, with an Inconel 718 ring encased by a carbon composite ring. The topology of the Inconel 718 ring was designed by the framework to accommodate the strain mismatch between the two materials caused by differing coefficients of thermal expansion. Experimental results indicate that the bi-material ring performed effectively and successfully accommodated the strain mismatch between the two rings. Overall, this research dem (open full item for complete abstract)

Committee: Robert Lowe (Committee Chair); Richard Beblo (Committee Member); Brent Bielefeldt (Committee Member); Rydge Mulford (Committee Member); Andrew Schrader (Committee Member) Subjects: Aerospace Engineering; Aerospace Materials; Engineering; Mechanical Engineering; Mechanics

Doctor of Philosophy, University of Toledo, 2024, Physics

Adjuvant administration of hyperthermia with radiation therapy in the treatment of cancer has been extensively studied in the past five decades. Concurrent use of the two modalities was found to lead to both complementary and synergetic enhancements in tumor management but presents a practical challenge. Their simultaneous administration using the same implantable seed source has recently been established theoretically through magnetically mediated heat induction and the utilization of ferromagnetic materials. Careful consideration, however, showed that regular ferromagnetic alloys lack the power to overcome blood perfusion at clinically measured rates. We characterized the newly developed thermo-brachytherapy (TB) seed that combines a sealed radioactive source with a ferrimagnetic ceramic (ferrite) core, serving as a self-regulating hyperthermia source when placed in an alternating electromagnetic field. A TB seed structure is based on the Low Dose Rate (LDR) brachytherapy seed, with the ability to simultaneously deliver heat to the target. To increase the heat production and uniformity of temperature distribution, we used hyperthermia-only (HT-only) seeds in the empty spaces within already-inserted implantation needles. The heat generation is due to eddy currents circulating in the seeds' thin metal shell; it depends drastically on the permeability of the core. We identified a soft ferrite material (MnZnFe2O4) as the best candidate for the core, owing to its high iii permeability, the hyperthermia range Curie temperature, adjustable through specific material composition, and a sharp Curie transition. By measuring the magnetic properties of ferrite samples with different compositions, the final core prototype with the optimal parameters was identified. For this purpose, the permeability as a function of temperature was calculated based on measured circuit parameters and material B-H curves. The thickness of the shell enclosing the ferrite co (open full item for complete abstract)

Committee: David Pearson (Committee Chair); Ambalanath Shan (Committee Member); Nikolas Podraza (Committee Member); Mersiha Hadziahmetovic (Committee Member); Aniruddha Ray (Committee Member) Subjects: Medicine; Physics

MS, University of Cincinnati, 2023, Engineering and Applied Science: Materials Science

Aluminum and its alloys have been researched on a wide scale for different applications due to their unique properties and potential applications in different industries. Though Al-Co system is well-established, it still lacks research in the Al-rich side (<5 wt.% Co) for elevated temperature stability. This study evaluates the effect of Co and Sc additions to pure Al in terms of high temperature stability and improved mechanical properties through an integrated experimental and computational approach. This work has been carried out in the eutectic region which studies the binary Al-0.75 wt.% Co, Al-1 wt.% Co and Al-1.25 wt.% Co and the ternary Al-1 wt.% Co-0.1 wt.% Sc systems. These alloys were first investigated using the Calculation of Phase Diagrams (CALPHAD) methodology to study the phases present and their volume fractions by plotting phase diagrams. Solidification behavior was analyzed through Scheil calculations. Nucleation, growth and coarsening of precipitates was studied using the TC-PRISMA module of Thermo-Calc. The obtained data was then used to compare with experimental results. In the experimental part, these alloys were fabricated by vacuum arc melting (VAM). Cast alloys were heat treated at 300°C from the as-cast condition with different ageing times up to 1500 hours. Optical microscopy, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis were carried out to characterize the alloys, examine the eutectic structure and verify the present phases. Mechanical properties (strength) of the alloy in as-cast and aged conditions were evaluated using Vickers microhardness tests. Obtained data was used to evaluate the high temperature stability of these alloys. Prepared alloys demonstrate different eutectic microstructures depending on the Co content, consisting of hypoeutectic to complete eutectic nature. As per the predictions by Thermo-Calc, presence of Al-Co intermet (open full item for complete abstract)

Committee: Dinc Erdeniz Ph.D. (Committee Chair); Matthew Steiner Ph.D. (Committee Member); Eric Payton Ph.D. (Committee Member) Subjects: Materials Science

Master of Science in Engineering, Youngstown State University, 2023, Department of Mechanical, Industrial and Manufacturing Engineering

The field of metal additive manufacturing has experienced significant growth in recent years, and Laser Hot Wire Directed Energy Deposition (LHW-DED) has emerged as a popular technology due to its ease of use and ability to produce high-quality metal parts. In this study, we used a nonlinear transient thermo-mechanical coupled finite element model (FEM) in ANSYS APDL to conduct a detailed thermal and structural analysis of the laser hot wire DED metal additive manufacturing process. This analysis aimed to characterize the distortion caused by thermal effects and investigate the transient thermal process. In this study H13 iron chromium alloy material was deposited on an A36 low carbon steel substrate using a bidirectional laser toolpath. To record the temperature profile during printing, we employed a FLIR Infrared (IR) camera, while thermocouples mounted to the base plate measured heat transfer for validation purposes. Post-processing analysis was conducted using the CREAFORM laser 3D scan and Geomagic-X software to measure deformation from the nominal printed geometry. Overall, this study provides a significant contribution to our understanding of laser hot wire DED metal additive manufacturing, which will undoubtedly lead to further advancements in the field. This research has the potential to improve the productivity and quality of the additive manufacture of metals.

Committee: Kyosung Choo PhD (Advisor); Jae Joong Ryu PhD (Committee Member); Alexander H. Pesch PhD (Committee Member) Subjects: Aerospace Materials; Engineering; Materials Science; Mechanical Engineering

Master of Science (M.S.), University of Dayton, 2021, Mechanical Engineering

Non-contact instrumentation methods are becoming more prevalent in the realm of structural testing for collecting experimental data to correlate to finite element models. Thermo-elastic stress analysis is a type of non-contact method that has been gaining popularity in its use, however, criteria for how to correlate this data to finite element models has not been developed. As this method produces an averaged image over a span of cyclical loading, assessing the quality of the image is the first step in determining how to develop criteria for correlation. Included herein is an experiment that employs a thermo-elastic stress analysis system that utilizes a microbolometer to capture infrared images from the heat produced from a dogbone specimen. These images are then compared to a reference image, and image quality indices and an error index are produced for each set of images. These values are evaluated and a determination is made on how to utilize them for correlating the model strain values to the strain values measured by the thermo-elastic stress analysis system.

Committee: Dennis Buchanan (Advisor); David Myszka (Committee Member); Robert Lowe (Committee Member) Subjects: Mechanical Engineering; Optics; Scientific Imaging; Statistics

Doctor of Philosophy, The Ohio State University, 2019, Welding Engineering

This work builds upon the previous research regarding hydrogen assisted cracking (HAC) of low alloy steel to nickel-base filler dissimilar metal welds (DMWs). In particular, this work is focused on DMWs commonly experienced in offshore oil and gas production systems in subsea use. The HAC tendency of these welds has been attributed to formation of susceptible microstructures at the fusion boundary during welding. As such, a post-weld heat treatment (PWHT) is utilized to temper these microstructures as well as relieve residual stresses. However, these microstructures can persist even after PWHT due to the steep compositional gradient driving migration of carbon from the base metal toward the fusion boundary and into the partially mixed zone (PMxZ) of the weld. The degree to which this migration occurs is a function of materials selection (base metal and filler metal) as well as weld and PWHT procedure. Due to this phenomenon, there is a balance that must be found to provide tempering of the susceptible microstructures that form during welding and limiting the formation of new susceptible microstructures during PWHT. Previous research has established a test method in the form of the delayed hydrogen cracking test (DHCT) which can delineate the effects of materials combination, weld procedure, and PWHT on HAC of DMWs. This test's qualitative ranking of susceptibility agreed well with industry experience. The current study worked towards refining the test methodology investigating the effects of test parameter influence on realized results. Of the investigated variables, it was found that how the test samples are coated is of primary importance where a consistently exposed fusion boundary scheme providing the most repeatable result in test. Additionally, a comparison was made between the test hydrogen charging condition which uses a dilute acid and constant current density of 10mA/cm2 and the service environment which is seawater with a constant potential (-8 (open full item for complete abstract)

Committee: Boian Alexandrov Ph.D (Advisor); Antonio Ramirez Ph.D (Committee Member); Carolin Fink Ph.D (Committee Member); Matthew Hamilton Ph.D (Committee Member) Subjects: Engineering; Materials Science

Master of Science, The Ohio State University, 2019, Aero/Astro Engineering

With aircraft and aircraft engine manufacturers' goal to create lighter more efficient components, there has been a trend of replacing traditional aircraft materials such as aluminum and titanium with various composites. The high strength to weight ratio, and application specific manufacturing of composites, make them excellent candidates for components such as fan blades, engine cases, fuselages, and even parts of wings. However, from the rigorous testing that must be passed to certify airworthiness, comes a need for computational modeling of these composite components to greatly reduce the costs incurred from manufacturing to final testing. Some of the most costly testing comes from the blade out engine test to prove that a fan blade dislodged from the rotor will be contained by the engine case. When attempting to model an impact situation, where the force is applied transversely to the case, it becomes necessary to know the properties of the polymer matrix, because it is the primary factor affecting the strain rate dependency and failure of the composite as a whole. The purpose of this study is to simultaneously measure the full field thermal and full field deformation response of epoxy resin PR-520 in tension, compression, and torsion tests conducted at strain rates of approximately 0.01 s-1, 1.0 s-1, and 350 s-1. 2-D and 3-D digital image correlation is used for full-field measurement of deformation, and high-speed infrared thermography is used for simultaneous full-field temperature measurements. The testing is conducted on several test apparatus, a servo-hydraulic load frame for the low and intermediate rate tests, and a tension, compression, and torsion Split-Hopkinson bar for the high rate tests, respectively. The results show a coupling between temperature change and strain in the test specimens, with cooling occurring during elastic deformation, and heating occurring during plastic deformation. The results also show a dependence of both thermal and me (open full item for complete abstract)

Committee: Amos Gilat (Advisor); Prasad Mokashi (Committee Member) Subjects: Aerospace Engineering; Mechanical Engineering

Master of Science, University of Akron, 2017, Geology-Environmental Geology

Scrap tires are shredded and kept in monofills as one way of disposing or storing them for further processes such as recycling. Although monofills are safer than other means of disposing tires, long-term storage in fills and stockpiles, where the shredded tires are in a compressed state, has led to incidences of tire fires. In order to safely and more efficiently manage shredded tire monofills, it is imperative to understand the heat generation process in such settings. This study is an experimental investigation performed with the overall aim of determining the directional variations of the bulk thermal conductivity of shredded tires. To approximate the situation at monofills, an experimental apparatus was designed and constructed using an open-end steel drum with a diameter of 0.28 m (11 in) and 0.85 m (33.5 in) height. Heat was generated by compression of interstitial air/voids, and temperature distribution was measured when heat was in transit across the bulk volume of shredded tires. Experiments were conducted on three shred sizes: 12.5 mm (0.5 in), 25 mm (1 in), and 150 mm (6 in) to determine thermal conductivity variations as a function of size, density and compressibility. The three shred sizes correspond to three experimental set-ups. A fourth configuration was composed of 150 mm (6 in) shred sizes with a 75 mm (3 in) covering of mine spoils to determine the contribution of mine spoils to the temperature difference, heat flux, thermal conductivity and compressibility of interstitial air of bulk shredded tires. The compression/strain of the large size tire shreds was found to be higher than that of small size tire shreds. The reloading experiment also shows that shredded tires compress less during the second round of loading (i.e., showing a low level of hysteresis), although both the first time loading and the reloading curves depict a similar non-linear stress-strain behavior. One of the ramifications of the results is the finding that the t (open full item for complete abstract)

Committee: Ira D. Sasowsky Dr. (Advisor); David N. Steer Dr. (Committee Member); John M. Senko (Committee Member) Subjects: Environmental Engineering; Environmental Geology

Master of Science (M.S.), University of Dayton, 2017, Renewable and Clean Energy

Photovoltaic-thermal (PVT) technology is a relatively new technology that comprises a photovoltaic (PV) panel coupled with a thermal collector to convert solar radiation into electricity and thermal energy simultaneously. Since cell temperature affects the electrical performance of PV panels, coupling a thermal collector with a PV panel contributes to extracting the heat from the latter to improve its performance. In order to ensure a sufficient temperature difference between the PV cells and the working fluid temperature entering the thermal collector, the circulated water has to reject the heat that has been removed from the PV cells into a relatively colder environment. Borehole thermal energy storage (BTES), which is located underground, often serves as this relatively colder environment due to the stability of underground temperatures, which are usually lower than the working cell temperature. Use of BTES is especially beneficial in summer, when the degradation in cells efficiency is highest. In this thesis, the electrical, thermal, and economic performances of a PVT system are evaluated for three types of buildings -- residential, small office, and secondary school -- in two different climates in the United States, one of which is hot and the other is cold. For each case, two different scenarios are considered. In the first, a PVT system is coupled with BTES, and a ground-coupled heat pump (GCHP) is in use. In the second, a PVT system is coupled with BTES and no GCHP is in use. Each scenarios' GCHP performance is assessed as well. Both the PVT collectors and GCHP performances are evaluated over short and long-term to study the effect of continued ground heat imbalance on both technologies.

Committee: Andrew Chiasson Ph.D. (Committee Chair); Youssef Raffoul Ph.D. (Committee Member); Robert Gilbert Ph.D. (Committee Member) Subjects: Energy; Engineering; Mechanical Engineering

Master of Science, The Ohio State University, 2016, Welding Engineering

Pipes of solid solution strengthened Ni-based alloys, as Alloy 826 and Alloy 800H, have been used for high temperature service in once through steam generators (OSTGs) on off-shore platforms. The oil and gas industry is seeking to increase service temperature, improve service reliability, and extend service life to 40 years of such installations. Alloy 230 has better-high temperature stability and mechanical properties, and higher service temperature than Alloys 825 and 800H, and is therefore considered as a potential replacement of these alloys in newly built OTSGs. However, the weldability and the high temperature service behavior in welds of Alloy 230 have not been thoroughly investigated yet. This study is a comprehensive comparative research focused on susceptibility to solidification cracking and stress relief cracking in Alloys 800H, 825, and 230. To evaluate the solidification behavior and solidification cracking susceptibility in these alloys, the Cast Pin Tear Test (CPTT), thermodynamic simulations with Thermo-Calc, and the technique of Single-Sensor Differential Analysis (SS-DTA) were used. The results revealed that Alloy 230 and Alloy 825 were more resistant to solidification cracking than Alloy 800H, due to narrower solidification temperature range and crack back filling with eutectic constituents. The OSU Stress Relief Cracking (SRC) Test was applied to evaluate the susceptibility to stress relief cracking in autogenous gas tungsten arc welds of the investigated alloys. None of the three alloys failed by stress relief cracking mechanism while loaded at stress equal to 90% of the high temperature yield strength at 650 oC for 8 hours.. Alloys 825 and 800H showed significant amount of stress relief, while Alloy 230 sustained the applied load at 650C with almost no stress relief. Tensile testing at 650 oC after the 8 hours SRC test showed that the autogenous weld in Alloy 230 had significantly higher yield and tensile strength and slightly lower el (open full item for complete abstract)

Committee: Boian Alexandrov (Advisor); Avraham Benatar (Advisor) Subjects: Materials Science; Metallurgy

Master of Science, The Ohio State University, 2016, Welding Engineering

High manganese steels are potential candidates for use in cryogenic applications as they exhibit desirable low temperature properties and are a cost-effective alternative to high-Ni steels (i.e. 9%Ni steel, Type 304L) and Invar alloys. Their cryogenic properties are derived from the austenite stabilizing ability of manganese. A potential use for these steels is in the fabrication of liquefied natural gas (LNG) storage tanks. The demand for natural gas is expected to increase 65% by the year 2040 and thus the need for cost-effective materials to replace conventionally used high-Ni alloys during construction of storage and transportation tanks is relevant. When fabricating these LNG tanks, welding is a critical procedure and thus the weldability of these high manganese steels must be evaluated. In this study, the effect of tungsten (W) and boron (B) additions on the microstructure and solidification cracking susceptibility of Fe-Mn-C filler metals was evaluated. Five compositions with tungsten additions up to 4.7 wt% and boron additions up to 27 ppm have been evaluated. Susceptibility to solidification cracking of these filler metals was determined using the Cast Pin Tear Test (CPTT). Solidification simulations were conducted using the Scheil approximation within Thermo-Calc™ and actual solidification temperature range measurements were conducted using the Single-Sensor Differential Thermal Analysis (SS-DTA™) technique. Metallurgical characterization was carried out using both optical microscopy, and scanning electron microscopy. The objective of this study was to determine the optimum range of tungsten and boron additions within the compositional range of interest that provides adequate resistance to weld solidification cracking. Results from Scheil simulations indicated only slight variations in the solidification temperature range (STR) among the alloys tested. The simulations showed that W additions lowered the liquidus temperature and subsequently the STR w (open full item for complete abstract)

Committee: John Lippold (Advisor); Antonio Ramirez (Committee Member) Subjects: Engineering; Materials Science; Metallurgy

Master of Science, The Ohio State University, 2016, Welding Engineering

In the oil & gas industry, extraction of oil reserves from pre-salt subsea oil fields requires pipelines and risers to be joined with welds that overmatch the X65 pipe yield strength by 100 MPa, have high toughness, and do not utilize a PWHT. In typical oil extraction, these internally clad pipes are welded with fill passes of Alloy 625 that match the internal clad, however, the strength requirement for reeling is not met with this alloy. To meet the strength requirement, low alloy steel consumables were studied as fill passes to join X65 pipes that are internally clad with Alloy 625 with root passes welded using 625 filler metal. The problem with this metallurgical combination is that solidification cracking can occur in the low alloy steel weld passes that have been diluted by Alloy 625. Computational modeling was performed to screen potential consumables and welding trails were completed for consumables that demonstrated compatibility. Upon establishing welding parameters, bead-on-plate design of experiments were performed with low alloy steel (ER100S-G) welded over two different nickel-based alloys (Alloy 625 and Alloy 686). Buffer layer solutions were also tested using two other Ni-based alloys, UTP A 80 Ni and Alloy 625 LNb, to isolate the root pass material from the fill pass material. Solidification cracking was eliminated in bead-on-plate welds of ER100S-G over Alloy 625 using small weave amplitudes, however, Alloy 686 was determined to have better compatibility with the low alloy steel filler metal to avoid solidification cracking. Welding experiments in a narrow groove were performed for the compatible combination, ER100S-G fill passes over a root pass of Alloy 686, and solidification cracking was eliminated from the fill pass welds. During this study, a defect previously thought to occur only in castings has been identified in welds of low alloy steel filler metals over Ni-based alloy substrates. Referred to in this study as “shrinkage porosity”, (open full item for complete abstract)

Committee: Boian Alexandrov Dr. (Advisor); Avraham Benatar Dr. (Committee Member) Subjects: Engineering; Materials Science; Metallurgy

Doctor of Philosophy, University of Toledo, 2016, Mechanical Engineering

Thermoplastic composites are suitable alternatives to metals in some load-bearing applications such as in the automotive industry due to a large number of advantages they present. These include light weight, ease of processing for complex geometries at high production rate, outstanding cost to performance ratio, ability to reprocess, and corrosion resistance. Addition of fillers such as talc or reinforcements such as short glass fibers can improve the mechanical performance of unreinforced thermoplastics to a high degree. Components made of thermoplastic composites are typically subjected to complex loadings in applications including static, cyclic, thermal, and their combinations. These applications may also involve environmental conditions such as elevated temperature and moisture which can dramatically affect their mechanical properties. This study investigated tensile, creep, fatigue, creep-fatigue interaction, and thermo-mechanical fatigue (TMF) behaviors of five thermoplastic composites including short glass fiber reinforced and talc-filled polypropylene, short glass fiber reinforced polyamide-6.6, and short glass fiber reinforced polyphenylene ether and polystyrene under a variety of conditions. The main objectives were to evaluate aforementioned mechanical behaviors of these materials at elevated temperatures and to develop predictive models to reduce their development cost and time. Tensile behavior was investigated including effects of temperature, moisture, and hygrothermal aging. Kinetics of water absorption and desorption were investigated for polyamide-6.6 composite and Fickian behavior was observed. The reductions in tensile strength and elastic modulus due to water absorption were represented by mathematical relations as a function of moisture content. In addition to moisture content, aging time was also found to influence the tensile behavior. A parameter was introduced for correlations of normalized stiffness and strength with different aging t (open full item for complete abstract)

Committee: Ali Fatemi Dr. (Advisor); Mohamed Samir Hefzy Dr. (Committee Member); Saleh Jabarin Dr. (Committee Member); Joseph Lawrence Dr. (Committee Member); Efstratios Nikolaidis Dr. (Committee Member) Subjects: Engineering; Mechanical Engineering

Master of Science, University of Akron, 2016, Chemical Engineering

Poly (N-isopropylacrylamide) (pNIPAAm), a thermo-responsive polymer that exhibits a lower critical solution temperature (LCST) of 32 °C in water has found an extensive use in tissue engineering and bioengineering applications in general. Since it is soluble in water, one of the main challenges that limit its applications in an aqueous environment is the tedious and expensive electron beam or plasma based procedures to retain it on a substrate. In this study, we report the use of various types of organosilanes to form siloxane networks for immobilizing pNIPAAm onto Si-wafer and silica glass substrates in a simple two-step approach: spin coating followed by thermal curing. Attempts are made to elucidate the entrapment mechanism and factors that affect such entrapment. It was found that the entrapment occurs via the segregation of high surface tension organosilanes towards the substrate at a temperature higher than the glass transition temperature (Tg) of pNIPAAm and simultaneous cross-linking of the segregated organosilane molecules that form siloxane networks. Organosilanes having low surface tension were found to segregate towards the air-film interface leading to poor entrapment. Factors such as polarity and hydrogen bonding were found to influence the retention of those organosilanes in the blend film during spin-coating and thermal annealing and subsequent film retention after 3 days of soaking in cold water. Additionally, organosilanes that are allowed to hydrolyze and oligomerize in the blend solution prior to spin-coating also resulted in higher organosilane retention and subsequently, thicker retained blend films compared to solutions that were spin-coated immediately after preparation. Substrates utilizing those organosilanes to entrap pNIPAAm resulted in stable films that exhibited thermo-responsive behaviors that were verified by wettability measurements. Rapid cell sheet detachment (<5 min) of embryonic mouse fibroblast cells were obtained on all su (open full item for complete abstract)

Committee: Bi-min Zhang Newby Dr. (Advisor); Gang Cheng Dr. (Committee Member); Jie Zheng Dr. (Committee Member) Subjects: Biomedical Research; Chemical Engineering; Chemistry; Materials Science; Polymers

Doctor of Philosophy, University of Toledo, 2016, Physics

Hyperthermia has long been known as a radiation therapy sensitizer of high potential; however successful delivery of this modality and integrating it with radiation have often proved technically difficult. We present the dual-modality thermo-brachytherapy (TB) seed, based on the ubiquitous low dose-rate (LDR) brachytherapy permanent implant, as a simple and effective combination of hyperthermia and radiation therapy. Heat is generated from a ferromagnetic or ferrimagnetic core within the seed, which produces Joule heating by eddy currents. A strategically-selected Curie temperature provides thermal self-regulation. In order to obtain a uniform and sufficiently high temperature distribution, additional hyperthermia-only (HT-only) seeds are proposed to be used in vacant spots within the needles used to implant the TB seeds; this permits a high seed density without the use of additional needles. Experimental and computational studies were done both to optimize the design of the TB and HT-only seeds and to quantitatively assess their ability to heat and irradiate defined, patient-specific targets. Experiments were performed with seed-sized ferromagnetic samples in tissue-mimicking phantoms heated by an industrial induction heater. The magnetic and thermal properties of the seeds were studied computationally in the finite element analysis (FEA) solver COMSOL Multiphysics, modelling realistic patient-specific seed distributions. This distributions were derived from LDR permanent prostate implants previously conducted at our institution; various modifications of the seeds' design were studied. The calculated temperature distributions were analyzed by generating temperature-volume histograms, which were used to quantify coverage and temperature homogeneity for a range of blood perfusion rates, as well as for a range of seed Curie temperatures and thermal power production rates. The impact of the interseed attenuation and scatter (ISA) effect on radiation dose distributio (open full item for complete abstract)

Committee: Diana Shvydka Ph.D. (Advisor); E. Ishmael Parsai Ph.D. (Committee Member); Victor Karpov Ph.D. (Committee Member); Yanfa Yan Ph.D. (Committee Member); Sorin Cioc Ph.D. (Committee Member) Subjects: Biophysics; Medicine; Physics

Doctor of Philosophy (Ph.D.), University of Dayton, 2015, Mechanical Engineering

An experimental campaign was undertaken to investigate the thermo-acoustic properties of a bluff-body stabilized flame in an atmospheric pressure facility at the Air Force Research Laboratory. Of particular interest were the possible interactions between the acoustic properties of the test rig, the vortex shedding due to the presence of the bluff-body, and the unsteady heat release within the chamber. An analysis of the vortex shedding modes due to the bluff-body and the acoustic modes indicated that there are regions in the operating envelope where the two mode types share similar frequencies given an operating condition, creating a scenario where feedback might be possible. Further investigation into the fluctuating velocity components in the wake of the bluff-body indicated that the Strouhal number is not single-valued, and that vortices of varying sizes, and accompanying characteristic frequencies, are shed from a single bluff-body. With previous research indicating that lean blow-off is preceded by local extinctions within the reaction zone, and blow-off being closely related to the ratio of chemical and fluidic time scales, an experiment was conducted to determine whether or not flames undergoing thermo-acoustic instability also exhibit regions of decreased residence time. This experiment concluded that the regions of acoustically-coupled flames which undergo large-scale oscillations do, in fact, correlate with decreased residence time. This conclusion links both lean static stability and near-stoichiometric dynamic stability to simple time scales prescribed by vortex behavior in the wake of a bluff-body. An investigation was conducted which utilized simultaneous high-speed particle image velocimetry (PIV), planar laser-induced fluorescence (PLIF) and pressure measurements in the near-wake region of a bluff-body stabilized flame. In addition to the simultaneous measurements listed, high-speed broadband chemiluminescence was also collected. The 2-D (open full item for complete abstract)

Committee: Ahmad Kashani Ph.D. (Committee Chair); Scott Stouffer Ph.D. (Committee Member); Vincent Belovich Ph.D. (Committee Member); Kevin Hallinan Ph.D. (Committee Member) Subjects: Mechanical Engineering

PhD, University of Cincinnati, 2014, Engineering and Applied Science: Materials Science

This research is focused on the synthesis, characterization and properties of epoxy based coatings, blended and cured with thermoplastic nylon-6 and organoclay modified nylon-6. Epoxy resins has 2 major drawbacks: (1) extremely brittle nature and (2) moisture absorption. The first problem is solved by incorporation of nylon-6 in epoxy, and the second problem is solved by incorporation of nano-clay in the nylon-6/epoxy system. A novel polymerization process of synthesizing nylon-6 in solution was developed in this work, which resulted in simple and efficient process of blending nylon-6 with epoxy resin resulting in homogenous blends of nylon-6 with epoxy. The storage modulus in glassy region for nylon-6/epoxy composites decreased linearly as nylon-6 weight % increased, along with decrease in glass transition temperature from 70 ?C to 30 ?C. The storage modulus in rubbery region increased compared to control epoxy. The control epoxy used in the system was water based EPIREZ5522-WY-55, thermally heated without using curing agent. The curing agent was not used to study the effect of nylon-6 on storage modulus in rubbery region. These results indicated that sole nylon-6 increased cross-link density of epoxy resin, which was further verified by determining fractional epoxy conversion by monitoring characteristic epoxy peak at 914 cm-1 in FTIR, which increased with increase in nylon-6 wt.%. The nylon-6/epoxy coatings applied on Al-2024 T3 substrate were tested for anti-corrosion. The coating containing 10% of nylon-6 in epoxy showed the best performance, compared to other compositions, thermally heated epoxy coating and epoxy-amine system. Comparison with formulation cured by thermal treatment of epoxy showed that nylon-6 alone without standard curing agent is effective in improving the properties, while comparison with standard epoxy-amine system suggested that the novel technology can be effectively used in practical applications. Then clay/nylon-6 nanocomposites were s (open full item for complete abstract)

Committee: Jude Iroh Ph.D. (Committee Chair); F James Boerio Ph.D. (Committee Member); Raj Manglik Ph.D. (Committee Member); Rodney Roseman Ph.D. (Committee Member) Subjects: Materials Science

Master of Science in Engineering, University of Akron, 2014, Civil Engineering

This paper presents an in-depth theoretical review of thermal piling technology and the advantages offered if used in the state of Ohio and viably other states in the U.S. Midwest. Thermal piling systems not only operate as a structural foundation system, but they also serve as heating and cooling mechanisms by tapping into ground source energy when used in conjunction with ground source heat pumps. Greenhouse gas emissions continue to increase due to increasing heating and cooling demands. The state of Ohio emits large numbers of CO2 due to heating and cooling of businesses and residential areas. There are vast concerns that if the state of Ohio does not take initiative in reducing greenhouse gas emissions, the consequences will be detrimental to the health and safety of the public along with the economy. This paper discusses the environmental and financial benefits of thermal piling and opens up dialogue for the possibility of full-scale testing and research of energy piles in Ohio.

Committee: Robert Liang Dr. (Advisor); Junliang Tao Dr. (Advisor) Subjects: Civil Engineering

Doctor of Philosophy, Miami University, 2013, Chemistry and Biochemistry

This dissertation describes the development and application of methods and instrumentation for qualitative and quantitative sample analyses by infrared and Raman spectroscopies. An introduction to the concepts and methods utilized is provided in Chapter 1. A comparative evaluation of solid-core silver halide fiber optics and hollow silica waveguides was performed on the basis of the transmission of mid-infrared radiation using a fiber optic coupling accessory and an infrared microscope is presented in Chapter 2. Increased transmission was reproducibly observed between two identical hollow waveguides due to minimization of insertion and scattering losses resulting from the hollow core. Chapter 3 presents an evaluation of a mid-infrared, attenuated total (internal) reflection (ATR) probe accessory utilizing hollow waveguides based on transmission and signal-to-noise. Quantitative analyses of aqueous succinylcholine chloride and ethanol solutions were also performed. An in situ Raman study of nitrogen incorporation in thin films of zinc oxide using a temperature-controlled reaction cell is discussed in Chapter 4. Monitoring nitrogen incorporation in thin films of zinc oxide at elevated temperatures in the presence of nitrogen-containing precursor reagents proved inconclusive using the proposed method. Chapter 5 presents an evaluation of dispersive and Fourier transform (FT-) Raman spectroscopies for on-line process control in the bottling industry. FT-Raman was determined to be more applicable for on-line determinations of poly(ethylene terephthalate) bottle thickness due to the availabilities of such benefits as increased laser power and fluorescence rejection. Preliminary data from the development of an inverted ATR imaging microscope are discussed in Chapter 6. The inverted optical design of the microscope permits simultaneous viewing of the sample with white light and the collection of infrared spectral images. Summaries of the presented research are pro (open full item for complete abstract)

Committee: André Sommer PhD (Advisor); Neil Danielson PhD (Committee Chair); Jonathan Scaffidi PhD (Committee Member); David Oertel PhD (Committee Member); Lei Kerr PhD (Committee Member) Subjects: Analytical Chemistry; Chemistry