Master of Science in Engineering, University of Akron, 2018, Mechanical Engineering

Three dimensional (3D) and two dimensional (2D), non-isothermal, transient Computational Fluid Dynamics (CFD) simulations are conducted for Carreau-Yasuda rubber mixing with a set of two-wing rotors in a partially filled chamber. The main objective is to analyze the effect of different fill factors of rubber and different speed ratios of rotors on dispersive and distributive mixing characteristics by simulating 15 revolutions of the rotors rotating at 20 rpm. 50%, 60%, 70%, 75%, 80% and 90% are the six different fill factors chosen for the 2D study. For 3D study, 60%, 70%, 75% and 80% fill factors of rubber are chosen. And a 2D case study with 1.0, 1.125 and 1.5 speed ratios of rotors are conducted to analyze their effects on dispersive and distributive mixing. An Eulerian multiphase model is employed to simulate two different phases, rubber and air, and the volume of fluid (VOF) technique is used to calculate the free surface between two phases, in addition to the continuity, momentum and energy equations. To characterize non-Newtonian, highly viscous rubber, shear rate and temperature dependent Carreau-Yasuda model has been used. A set of 2500 (for 2D study) and more than 3600 (for 3D study) massless particles are injected after a certain period of time to calculate several quantities in terms of dispersive and distributive mixing. Specifically, mixing index and cumulative distribution of maximum shear stress are assessed for the dispersive nature of mixing. Inter-chamber and axial particle transfer rates along with cluster distribution index (CDI), scale of segregation (SOS) and length of stretch (LOS) are calculated for investigating distributive nature of the mixing process. Viscous heat generation rate and change of molecular viscosity with time are calculated to see the rise of temperature inside the domain with time. Both the Eulerian and Lagrangian results showed that, fill factors between 70% and 80% and speed ratio of 1.125 presented the most reasonable a (open full item for complete abstract)

Committee: Abhilash J. Chandy (Advisor); Scott Sawyer (Advisor); Jae-Won Choi (Committee Member) Subjects: Mechanical Engineering; Polymers

Master of Sciences (Engineering), Case Western Reserve University, 2018, Macromolecular Science and Engineering

Thermotropic Liquid Crystalline Polymers, which are materials made up of semi rigid rod-like molecules, have this unique property of orienting themselves during flow. This results in the formation of a very ordered melt phase which gives these materials a plethora of superior properties like high tensile modulus, good chemical resistance, very high thermal stability, flame retardant characteristics, dimensional stability etc. However, their cost prohibits their wide scale use and limits it to niche applications. This has engendered a lot of interest in the preparation of Thermoplastic/Liquid Crystal Polymer blends. Moreover, the fact that Liquid Crystal Polymers tend to reduce the melt viscosity, making the blend easier to process, is an added incentive in addition to their properties. Extension dominated flows have been long known to be more efficient in mixing as compared to shear dominated flows. Exploiting this concept, Carson and et al. at Case Western Reserve University have developed new mixing elements for the Twin Screw Extruder. These elements were proven to impart extensional forces as opposed to the shear forces imposed by the Kneading Blocks, resulting in better dispersive and dissipative mixing. This thesis aims to use these novel extensional mixing elements on a system of Polypropylene and Liquid Crystal Polymer compatibilized by a compatibilizer, to enhance mechanical and thermal properties of Polypropylene on addition of a low quantity of Liquid Crystal Polymer. Furthermore, this research also intends to compare the extensional mixing elements to the kneading blocks, which are the industry standard. All the extrusions were carried out on a co-rotating twin screw extruder, at two different temperatures of 285-295 °C and 220-230 °C. The purpose of using two different temperatures was to melt the Liquid Crystal Polymer to prepare blends in one case, whereas to keep it a solid and prepare composites in the other case.

Committee: João Maia (Advisor); David Schiraldi (Committee Member); Mike Hore (Committee Member) Subjects: Materials Science; Plastics; Polymer Chemistry; Polymers

Master of Science in Engineering, University of Akron, 2016, Mechanical Engineering

Mixing is a complex process in manufacturing where all the component ingredients are brought together by moving rotors in a closed chamber. Understanding mixing is very important in terms of evaluating the efficiency of the mixer and effect of various operating parameters such as rotor speed, ram pressure, temperature,fill factor, etc. With the physical mixing process always being partially filled, it is very important to determine the effect of fill factor and the best-operating fill ratio that yields the highest throughput. Mixing also controls the physical, chemical and mechanical properties required for downstream processing. Researches on the complex mixing process are not only limited to increase the productivity of the system but also to improve the quality of product and repeatability of the operation. Availability of modern high-performance computing resources and accurate mathematical models makes computational fluid dynamics (CFD) an important and necessary tool in understanding some of the complex physical and chemical phenomena associated with such industrial manufacturing problems. This research presents the calculation of various flow properties to determine the dispersive and distributive mixing in an internal mixer. Flow characteristics are calculated in terms of the velocity field and pressure distribution inside the chamber. Similarly, massless particles have been injected into the flow domain and the statistics of those particles have been used for determining the distributive and dispersive mixing characteristics for the various set of operating parameter. For simplicity, this study is conducted on the isothermal system where the viscous heat generation resulting temperature variation is assumed to be negligible. A series of 2D and 3D CFD simulations are carried out in a mixing chamber with various fill factors stirred by counter-rotating rotors. The Volume of Fluid (VOF) method has been used for capturing the interface between the rubber and ai (open full item for complete abstract)

Committee: Abhilash J. Chandy Dr. (Advisor); Jae-Won Choi Dr. (Committee Member); Siamak Farhad Dr. (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2023, Chemical Engineering

The translation of bench-scale nanoparticle synthesis procedures to continuous, up-scaled nanomanufacturing operations remains a challenging task. Nanoscale materials and devices hold great promise, however, low throughput and inconsistent quality limit their applications at a large scale. In spite of the commercial success of top-down approaches like photolithography and nanoimprint lithography, bottom-up approaches are predominantly bench-scale. The inherent intricacies of reaction or self-assembly kinetics in bottom-up procedures create difficulties in achieving consistent product quality. Scaling up bottom-up synthesis techniques suffer from erratic product output and poor functionality control. Nanoprecipitation represents one such commonly used bottom-up approach for nanoparticle synthesis. Such nanoprecipitation kinetics are rapid, occurring on the timescale of milliseconds. Mixing in conventional batch reactors fails to achieve concentration/temperature homogeneity on the precipitation timescale. Mixing and precipitation timescales diverge further as reactor volumes increase. Inhomogeneous kinetics results in a polydisperse nanoparticle population and heterogeneities in size-dependent properties. Hence, the primary goal of this work includes investigating different mixer types based on electrohydrodynamic mixing and confined jet mixing and their effectiveness in achieving uniform nanoparticle size and properties. The dissertation expands on the capabilities of the established electrohydrodynamic (EHD) mixer developed by Dr Winter and Dr Wyslouzil's research group at the Ohio State University. As a model system, polycaprolactone-polyethylene oxide and polystyrene-polyethylene oxide were used as block copolymers that exhibit mixing sensitive nanoparticle size properties. A number of operating parameters, including the solvent-to-antisolvent ratio and ground-to-electrified needle distance, were used to determine the versatility and limitations of the EHD mi (open full item for complete abstract)

Committee: Jessica Winter (Advisor); Barbara Wyslouzil (Committee Member); Nicholas Brunelli (Committee Member) Subjects: Chemical Engineering

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

The modern rubber industry is always in pursuit of improvements in the properties of the final product resulting from the mixing of the rubber compounds with different fillers and additives. Depending on the functional characteristics of the final product and thus the compounding ingredients, different types of mixers can be used for the rubber mixing process. Hence, the choice of an appropriate mixer is critical in achieving the proper distribution and dispersion of fillers in rubber, and a consistent product quality, as well as is the attainment of high productivity. Besides rotor design, operational parameters such as speed ratio and the orientation of the mixing rotors with respect to each other also play significant role in the mixing performance. With the availability of high-performance computing resources and high-fidelity computational fluid dynamics tools, understanding the flow field and mixing characteristics associated with rotor orientations, speed ratios and complex rotor geometries, has become more feasible over the last two decades. As part of this effort, all the simulations here are carried out in a 75% fill chamber with two counter-rotating rotors using a CFD code. In the phase angle and rotor design studies conducted here, the rotors rotate at 20 rpm even speed, whereas for speed ratio study, only the left rotor rotates at 20 rpm and the right rotor rotates at a speed, which is a multiple of 20 rpm by the speed ratio specified. The computational models used in this research are based on a finite volume method to simulate a partially filled mixer equipped with different tangential rotor types. The model solves for transient, isothermal and incompressible set of governing fluid equations for the mixing of non-Newtonian high-viscosity rubber. The research here considers phase angles of 45°, 90° and 180°, speed ratios of 1.0, 1.125 and 1.5, and rotor designs including 2-wing, 4-wing A and the 4-wing B rotors. Investigation of each parameter type (open full item for complete abstract)

Committee: Abhilash Chandy Ph.D. (Advisor); Povitsky Alex Ph.D. (Committee Member); Choi Jae-Won Ph.D. (Committee Member) Subjects: Fluid Dynamics; Industrial Engineering; Mechanical Engineering; Polymers

PhD, University of Cincinnati, 2001, Arts and Sciences : Mathematics

The almost sure central limit theorem (ASCLT) has been discovered by two works by Brosamler (1988) and Schatte (1988) and extensively studied in the past decade. In the dissertation we investigate ASCLT and its extensions to weakly dependent random variables. Its strong approximation is also considered for both independent and dependent random variables. The goal is to prove ASCLT, 'logarithmic' limit theorems and related invariance principles for weakly dependent random variables.

Committee: Magda Peligrad (Advisor) Subjects: Mathematics; Statistics

Master of Science in Engineering, Youngstown State University, 2013, Department of Mechanical, Industrial and Manufacturing Engineering

Not only due to its versatility and inexpensive availability, lab-on-a-chip integrates multitasks for a complete µTAS. Due to easy portability in micro-devices, microfluidics has potential to revolutionize in many applications that include food, pharmaceutical, biomedical and chemical industries, etc. Mixing is inevitable for the analysis of trace chemicals, drugs, bio-molecules, fluidic controls in microfluidics, etc. Such miniaturized microfluidics had already proven better over bulky instrumentations, because of time and transportation required in handling. In this work, both active and passive were computationally studied. Passive mixing is considered with the mass fraction at different velocities of various mixer models when the fluids are in contact with each other. A two dimensional comparative analysis was performed to see the degree of mixing on two standard geometries including T and Y for general purposes. Along with standard geometries including T & Y, combinatory models with more than two inlet ports were also investigated using ANSYS Fluent, finite volume software. The engulfment flow was the major reason responsible for the mixing process. The engulfment flow was one of the major reasons responsible for the mixing process. Diffusion is a dominant phenomenon in passive mixing at the junction where various inlets meet and convective process becomes prevalent. Identification of geometrical correlation with the flow field variables and mixing parameters are crucial for better mixing design. The active mixing would be mathematically modeled with additional body force in the momentum equation. Thus, active mixers are externally activated for better mixing possibilities than the time consuming and possible complex geometries in passive mixing. Concentration variances over time at the outlet were simultaneously compared in all models for mixing. Also average concentration was tracked over time so as to confirm uniformity in mixing. Active circular mixers w (open full item for complete abstract)

Committee: Yogen Panta PhD (Advisor); Hyun Kim PhD (Committee Member); Ganesh Kudav PhD (Committee Member) Subjects: Engineering; Fluid Dynamics; Mechanical Engineering

MS, University of Cincinnati, 2024, Engineering and Applied Science: Materials Science

Refractory complex concentrated alloys (RCCAs) are known for their high-temperature mechanical properties, but less attention has been given to their low-temperature thermophysical behavior. High-throughput calculation of phase diagrams (CALPHAD) was used to study the body centered cubic (BCC) phase dominance within the Nbx(MoTi2V4)100-x alloy system by adding Niobium (Nb) at atomic concentrations of x=9%,23%,and 37%, and two additional alloys where vanadium (V) is substituted with hafnium (Hf) and zirconium (Zr) to form Hf10Mo24Nb38Ti28 and Mo24Nb38Ti28Zr10 alloys. Alloys were tested to see the effect of Nb content on the superconducting transition temperature (TC) and the effect of substituting V with Hf or Zr on TC. This approach tests the common assumption of the correlation between VEC with TC, to clarify the role of composition relative to VEC. Button specimens were cast via vacuum arc melting and were measured for electrical resistivity at different temperatures using a Quantum Design DynaCool system. X-ray diffraction (XRD) was used to confirm the formation of the phases predicted by CALPHAD. Five out of the six alloy samples exhibited superconductivity, with some anomalies observed and addressed in this study. These results are compared to literature to enhance understanding of the results.

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

Master of Science, The Ohio State University, 1969, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2008, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, Miami University, 2024, Physics

This thesis presents a first demonstration of the suppression of cross-coupling between transverse degrees of freedom in a two-dimensional cold atom ratchet. Under ideal conditions, motion along each transverse degree of freedom is unaffected by driving(s) along the other axes of the system. In the case of a two-dimensional cold atom ratchet, where environmental noise in the form of photon recoils plays a critical role in the directed propagation of atoms, two-dimensional motion is difficult to control or predict due to highly nonlinear coupling between the driving along one axis and the resulting motion along the other. Here, atomic ratcheting is induced via a harmonic mixing of AC driving forces which produce motion without imparting any net force upon the atoms. When driving along both axes, these drivings may interfere with one another to produce additional, unwanted frequency mixing effects. However, this coupling may be suppressed through the use of quasi-periodic driving, where the driving frequencies applied along each axis are made incommensurate (i.e. the ratio ωx/ωy is made irrational). In addition to the primary result above, this work also investigates resonant activation induced ratcheting and the resulting interplay between harmonic mixing and resonant activation.

Committee: Samir Bali (Advisor); Imran Mirza (Committee Member); E. Carlo Samson (Committee Member) Subjects: Physics; Quantum Physics

PhD, University of Cincinnati, 2024, Engineering and Applied Science: Materials Science

In polymeric nanocomposites like automobile tire, nanofiller reinforcement are responsible for diverse mechanical property enhancements. Dispersion (aggregate break-up) and even distribution of the nanofiller in the matrix is a prerequisite for excellent reinforcement. Diverse factors impact homogeneous dispersion and distribution of these fillers in the polymeric matrixes. Moreover, formation of conductive networks in these systems is of utmost importance due to tear mitigation and static charge dissipation. Hence a great inter-play between homogenous dispersion and distribution plus formation of conductive network of nano-fillers is indispensable. Diverse factors affect dispersion, distribution, and the formation of conductive networks in polymeric nanocomposites. Surface properties and mixing conditions are factors that play a prominent role in the dispersion of silica fillers in polymers matrixes. When surface charges are present in the silica, they can induce aggregate-aggregate repulsions, which is not beneficial to the formation of conductive networks. Surface modification of silica can shield these repulsive interactions of aggregates. In this work, surface modification of silica was achieved by carbon coating during flame synthesis and by the means of silane coupling agents. The effect of mixing conditions on dispersion and distribution of nano aggregates was also studied. Ultra-small-angle X-ray scattering (USAXS) and microscopy were employed in the analysis of the results. The impact of surface carbon, silane coupling agents and mixing conditions on the van der Waals enthalpic attraction, a*, the excluded volume b* and molar excluded volume per aggregate B2 is determined. These parameters all describe and quantify the extent of dispersion in the studied systems.

Committee: Gregory Beaucage Ph.D. (Committee Chair); Jude Iroh Ph.D. (Committee Member); Russell Schwartz Ph.D M.A B.A. (Committee Member); Kabir Rishi Ph.D M.A B.A. (Committee Member); Jonathan Nickels Ph.D. (Committee Member) Subjects: Materials Science

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2024, Mathematics

We examine the dynamics of weighted composition operators on two function spaces. The first one is the space C∞(Ω, K) of K-valued smooth functions, where Ω ⊂ Rd is open and K is the real or complex scalar field. The second one is the space H(Ω) of holomorphic functions where Ω is a domain in the complex plane. The hypercyclicity of weighted composition operators on these two spaces has been completely characterized. The properties of weak mixing and mixing have also been characterized for this class of operators when acting on C∞(Ω, K). We study supercyclicity of these operators on these two spaces and compare it to other dynamical properties. We show that when acting on the space C∞(Ω, K), supercyclicity and weak mixing are equivalent properties, and when d = 1, such properties are also equivalent to mixing. When acting on the space H(Ω), we show that hypercyclicity coincides with mixing. Furthermore, when Ω is not conformally equivalent to the punctured unit disc, we show supercyclicity is equivalent to mixing. When Ω is conformally equivalent to an annulus or is n-connected for some n ≥ 3, then H(Ω) supports no supercyclic weighted composition operators, and when Ω is 2-connected, the properties of hypercyclicity, mixing and Devaney chaos are all equivalent.

Committee: Juan Bes PhD (Committee Chair); Robyn Miller PhD (Other); Benjamin Ward PhD (Committee Member); Kit Chan PhD (Committee Member) Subjects: Mathematics

Doctor of Philosophy, The Ohio State University, 2022, Mechanical Engineering

Evaporation of fuel droplets and mixing of fuel vapor with the oxidizer is the driving force for combustion reactions in many combustion devices. Since the flow in most practical combustion devices is turbulent, an understanding of the interactions among turbulence, mixing and reactions is necessary to improve fuel efficiency and reduce pollutant emissions. However, the effects of small-scale turbulence on the dynamics of evaporation and the resultant fuel vapor field are relatively less known. Fluctuating relative velocity and inhomogeneities in the fuel vapor field around the droplets have been observed to affect the droplet vaporization rates. Apart from the droplet-turbulence interactions, droplet-droplet interactions and turbulent mixing of the fuel vapor with the oxidizer are other aspects critical to the formation of a combustible mixture. The present work aims to contribute towards a physical understanding of the droplet-turbulence and droplet-droplet interactions as well as the turbulent mixing of fuel vapor by performing droplet-resolved direct numerical simulation (DNS). The effects of turbulence on the evaporation of droplets larger than the Kolmogorov length scale are investigated using droplet-resolved DNS. The DNS is performed using a numerical method based on the immersed boundary method (IBM) that is developed here to perform efficient DNS with multiple droplets. Firstly, an improved IBM for a general particulate flow is developed. The displaced forcing and the predictor-corrector forcing are proposed and validated for the prediction of drag and scalar gradients on the immersed body in incompressible flows. The method is extended for application to variable density flows using a low Mach formulation by carefully considering the phase change. The predictions of evaporation rates are validated by comparison with a correlation based on experimental data for both stationary and moving droplets. The droplet-resolved DNS considers droplets (open full item for complete abstract)

Committee: Seung Hyun Kim (Advisor); Jeffrey Sutton (Committee Member); Sandip Mazumder (Committee Member); Datta Gaitonde (Committee Member) Subjects: Aerospace Engineering; Mechanical Engineering

Master of Science, University of Toledo, 2022, Mechanical Engineering

In recent years, flexible and stretchable sensors have been a subject of intensive research to replace the traditional sensors made up of metal and semiconductors. This thesis has been conducted with the objective of exploring the possible applications of Graphene/PVDF nanocomposite in various kinds of flexible sensors as a potential sensing material. Initially, graphene/PVDF nanocomposite was synthesized by the solution-phase mixing method. A thin film of 20-22 μm was coated on a glass substrate to investigate the characteristics of the composite by using XRD and SEM techniques. This nanocomposite was best suited for piezoresistive-based sensors where the sensor senses the external stimuli and outputs the response in terms of change in electrical properties such as resistance, voltage, or current. The synthesized graphene/PVDF nanocomposite was coated on different kinds of substrates to make three different kinds of flexible sensors. They are airflow sensor, knittle pressure sensor, and accelerometer. The airflow sensor was designed and fabricated by applying a thin film of nanocomposite on the polyethylene (PE) substrate and placed inside a PVC pipe at an angle to the central axis of the pipe. The response of the sensor was tested by passing air at various speeds and recorded in terms of resistance change. The linearity and repeatability of the curves were observed. Temperature dependence on electrical conductivity was studied by heating and cooling the sample between room temperature and below the melting point of PVDF. Further, the sensing characteristics were simulated using COMSOL Multiphysics software, and the modeled data were compared with the experimental result. Another application of our in-house fabrication with the use of the nanocomposite is a knittle pressure sensor. The primary purpose of developing knittle pressure is to monitor health by either attaching to the skin or using it inside the health monitoring device. The use of fabric substrate a (open full item for complete abstract)

Committee: Ahalapitity Jayatissa (Advisor) Subjects: Mechanical Engineering

MS, University of Cincinnati, 2021, Engineering and Applied Science: Aerospace Engineering

Scramjets are a class of air breathing propulsion systems which operate at very high Mach numbers. Efficient mixing and combustion of fuel has been a concern in the field of scramjet propulsion for the last five decades. The residence time for mixing of fuel and air has been low due to the inherent design of the propulsion system. Therefore, it is very important to create scenarios for the efficient mixing of fuel and air in the combustor. Pulsation of jets has shown to improve penetration, mixing and entrainment. To do this requires the complex understanding of jets in supersonic crossflows. Previous research has shown the effect of forcing/exciting flows using novel techniques in a subsonic crossflow, thoroughly. But there is limited research on the pulsation of jets in supersonic crossflows. A novel technique to force or excite jets in a crossflow was suggested by Murugappan and Gutmark. This technique employed the Hartmann Sprenger tube in a device called the High Frequency Actuator. This device showed an improvement in the penetration of jets in supersonic crossflow but failed to explain the dynamic structures which created situations that helped improve mixing. Hence, CFD tools such as ANSYS Fluent were suggested to bridge this gap. An axisymmetric WALE LES model and a three dimensional Smagorinsky-Lilly model was constructed for the operation of the High Frequency Actuator in quiescent flow and supersonic crossflow, respectively. Two cases with frequencies 2400 Hz (St# 0.09) and 2933 Hz (St# 0.12) were studied in quiescent flow. Quiescent flow was used to understand the underlying physics associated with the creation of strong pulses inside the Hartmann Sprenger tube based on the quarter wave resonance tone and other harmonics. Spectral Proper Orthogonal Decomposition (SPOD) was used to identify the fundamental tones and strong coherent structures were observed in the flow field. Following that, forcing of jets in a supersonic Mach 2 cold flow was conduc (open full item for complete abstract)

Committee: Ephraim Gutmark Ph.D. (Committee Chair); Rodrigo Villalva Gomez (Committee Member); Paul Orkwis Ph.D. (Committee Member) Subjects: Aerospace Materials

Doctor of Philosophy, The Ohio State University, 2021, Mathematics

This dissertation deals with the fine structure of recurrence and mixing in probability measure preserving systems. In Chapter 2 we utilize sets of iterated differences in Ζ to obtain new Diophantine results dealing with odd polynomials. We then utilize this Diophantine results to obtain applications to ergodic theory and combinatorics. In particular, we obtain a new characterization of weakly mixing systems as well as a new variant of Furstenberg-Sarkozy theorem. In Chapter 3 we utilize R-limits, a new notion of convergence based on the classical Ramsey theorem, to show that any strongly mixing probability measure preserving action of a countable abelian group is almost strongly mixing of all orders. We also obtain new characterizations of the notion of strong mixing for actions of countable abelian groups. In Chapter 4 we utilize Gaussian measure preserving systems to prove the existence and genericity of measure preserving transformations which exhibit both mixing and rigidity behavior along families of independent polynomials.

Committee: Vitaly Bergelson (Advisor); Andriy Gogolyev (Committee Member); Alexander Leibman (Committee Member) Subjects: Mathematics

Doctor of Philosophy, The Ohio State University, 2021, Mathematics

In this dissertation we investigate two objects of central importance in ergodic theory: Furstenberg systems and multicorrelation sequences, as well as their interactions with combinatorics. This work is comprised of two main parts. In the first part we study Furstenberg systems. Among other things, we obtain a uniqueness theorem for Furstenberg systems and a characterization of countable weakly mixing amenable groups. In the second part we look at multicorrelation sequences for commuting measure preserving transformations. Under some ergodicity assumptions we show that a multicorrelation sequence has a decomposition of the form "structured part" plus an "error part". A close analysis of the methods used also yields results regarding sets of large returns as well as joint ergodicity.

Committee: Vitaly Bergelson (Advisor); Daniel Thompson (Committee Member); Alexander Leibman (Committee Member) Subjects: Mathematics

Doctor of Engineering, University of Dayton, 2020, Mechanical Engineering

The mixing industry has long depended on scaled down experimental methods combined with computational analysis to determine rotating mixer designs for customer applications. Most industrial mixing companies have the capabilities in-house to perform these experiments and the analysis to show customers the benefits of proposed designs. Experimental methods center around the calculation of power draw of the mixing unit, determined from a simple torque cell to determine power draw, and the blend time, shown through acid-base neutralization, which are both fairly simple to calculate from an scaled down rig and apply it to either customer designs or in the development of new mixers. The computational analysis centers around research done by mixing forefathers who developed methodology to calculate time dependent mixing parameters, like blend time, through steady state analysis due to restrictions in computational capacity. This is possible because the majority of the mixing can be observed from studying the macro-scale interactions. The impellers and baffles in a tank drive large scale motion which blends two different species or temperatures together to create a uniform mixture. Similar to rotating mixers, there are two main parameters used when analyzing static mixers. Similar to power draw for rotating mixers, static mixers are driven by the pressure drop across the mixer. The second parameter that is used to determine the effectiveness of a static mixer is the coefficient of variation, a statistical measurement of the degree of uniformity. This looks at a two-dimensional plane located downstream from the mixer outlet and determines the effectiveness of the mixer. This has been used for decades to provide the target for customer designs, but it provides a limited picture of the process. The snap shot on a two-dimensional plane provides a small window into what is happening in the entire process. The coefficient of variation also is merely a statistical paramete (open full item for complete abstract)

Committee: Markus Rumpfkeil Ph.D. (Advisor); Kevin Myers D.Sc. (Committee Member); Eric Janz (Committee Member); John Thomas Ph.D. (Committee Member); Robert Wilkens Ph.D. P.E. (Committee Member) Subjects: Chemical Engineering; Engineering; Mechanical Engineering

Master of Science, Miami University, 2020, Physics

Quantum states of light with a fixed number of photons are useful for several quantum optical technologies. In this thesis, we theoretically study single-photon generation in a three-mode optomechanical cavity with a Kerr type nonlinear medium. We begin by presenting a detailed derivation of the master equation under Born-Markov approximations describing the dissipative dynamics of our setup. Next, we concentrate on two system parameters, the three-mode coupling rate (g) and the strength of the Kerr nonlinearity (U) and analyze the detuning (Δ) dependence of the second-order correlation function g(2) to determine the photon statistics. As a key finding, we analytically conclude that the system can exhibit UPB for a wide range of detunings even with weak nonlinearities by adjusting the three-mode coupling. For instance, we find that the condition g(2) (0) < 1 can be met with fixing U== 0.69k and 푔 = 2k while κ here represents the optical mode decay rate. Moreover, we observe that the minimum of g(2) (0) shifts to higher detunings with increasing three-mode coupling rate and decreasing the Kerr nonlinear strength. With the current advancements in hybrid optomechanics, this work is experimentally feasible and can provide an alternate method for single-photon generation without relying on stringent conditions of CPB.

Committee: Imran Mirza (Advisor); Samir Bali (Committee Member); E. Carlos Samson (Committee Member) Subjects: Physics; Quantum Physics