Physical Sciences and Mathematics Commons^™

Mineral And Geochemical Attributes Of The Midcontinent Rift Sequence; An Application For Deep Carbon Dioxide Sequestration, Alsedik Mohamed Ali Abousif

Doctoral Dissertations

"The potential for using the Oronto Group of the Midcontinent Rift (MCR) Sequence for CO₂ sequestration has been disparaged because of low porosity-permeability characteristics, which are largely a result of extensive calcite cementation. This study investigated the potential for using the MCR as a target for CO₂ sequestration by examining reactions involving detrital host-rock minerals at high pressure-temperature conditions that could provide dissolved Ca²⁺, Mg²⁺, and Fe²⁺, and then precipitating these cations as carbonate minerals. The effect of carbonic acid on cement dissolution was also evaluated with respect to enhancing porosity and …

Enabling Near-Term Prediction Of Status For Intelligent Transportation Systems: Management Techniques For Data On Mobile Objects, Lasanthi Nilmini Heendaliya

Doctoral Dissertations

"Location Dependent Queries (LDQs) benefit from the rapid advances in communication and Global Positioning System (GPS) technologies to track moving objects' locations, and improve the quality-of-life by providing location relevant services and information to end users. The enormity of the underlying data maintained by LDQ applications - a large quantity of mobile objects and their frequent mobility - is, however, a major obstacle in providing effective and efficient services. Motivated by this obstacle, this thesis sets out in the quest to find improved methods to efficiently index, access, retrieve, and update volatile LDQ related mobile object data and information. …

Seismological Investigation Of The Okavango Rift, Botswana, Youqiang Yu

Doctoral Dissertations

The mechanisms of rifting have been intensively investigated using geological and geophysical techniques beneath mature rift zones. However, current understanding on the earliest stages of rifting is seriously limited. Here we employ recently archived data from 17 broadband seismic stations traversing northern Botswana to conduct the first shear wave splitting and mantle transition zone (MTZ) studies within the Okavango Rift Zone (ORZ). The ORZ is an incipient continental rift situated at the terminal of the southwestern branch of the East African Rift System. The resulting normal MTZ thickness and consistently rift-parallel fast polarizations imply an absence of significant thermal anomalies …

Pulsed Inductive Plasma Studies By Spectroscopy And Internal Probe Methods, Warner C. Meeks

Doctoral Dissertations

The broad effort of the Missouri Plasmoid Experiment is to elucidate the energy conversion processes in a pulsed inductive discharge due to the presence of plasma. The test article is a 440 to 490 kHz theta-pinch (or solenoidal) geometry coil with a stored energy of around 80 joules. In this work experimental hydrogen, helium, argon and xenon data at back-fill pressures of 10 to 100 mTorr (1.3 to 133.3 Pa) are obtained and interpreted. Spectral and internal probe studies were performed on MPX Mk.I and Mk.II devices, respectively. IR spectra were acquired in the Mk.I device for argon and xenon. …

Process Design, Dynamics, And Techno-Economic Analysis Of A Sustainable Coal, Wind, And Small Modular Nuclear Reactor Hybrid Energy System, Kyle Lee Buchheit

Doctoral Dissertations

"The availability of cheap electricity is one of the biggest factors for improving quality of life. With the debate on the effects of carbon dioxide emissions continuing, several countries have either implemented or are considering the reduction of emissions through various economic means. The inclusion of a monetary penalty on carbon emissions would increase the prices of electricity produced by carbon-based sources. The push for large-scale renewable sources of energy has met problems with regards to energy storage and availability. The proposed coal, wind, and nuclear hybrid energy system would combine a renewable energy source, wind, with traditional and stable …

Synthesis And Characterization Of Vanadium Oxide Nanomaterials, Tyler M. Fears

Doctoral Dissertations

"This dissertation focuses on the synthesis and characterization of vanadium oxide nanomaterials and neutron-transparent Li-ion battery electrolytes.

Vanadium oxide gels were synthesized via the epoxide-assisted gelation of VOCl₃ using epichlorohydrin in ethanol. This represents the first epoxide-assisted gelation developed for vanadium oxide gels and serves as a potential economical replacement for the fabrication of vanadium oxide gels via the hydrolysis of vanadium alkoxides. Though epoxide-assisted gelation has been demonstrated for a number of transition metal oxides, the gelation mechanism observed here for VOCl₃ appears to be unique.

While investigating the electrochemical and structural properties of lithium vanadates, it …

Approximation Methods In Relativistic Eigenvalue Perturbation Theory, Jonathan Howard Noble

Doctoral Dissertations

"In this dissertation, three questions, concerning approximation methods for the eigenvalues of quantum mechanical systems, are investigated: (i) What is a pseudo-Hermitian Hamiltonian, and how can its eigenvalues be approximated via numerical calculations? This is a fairly broad topic, and the scope of the investigation is narrowed by focusing on a subgroup of pseudo-Hermitian operators, namely, PT-symmetric operators. Within a numerical approach, one projects a PT-symmetric Hamiltonian onto an appropriate basis, and uses a straightforward two-step algorithm to diagonalize the resulting matrix, leading to numerically approximated eigenvalues. (ii) Within an analytic ansatz, how can a relativistic Dirac Hamiltonian be …

Synthesis And Electrochemical Studies Of Novel Ionic Liquid Based Electrolytes, Avinash Raju Vadapalli

Doctoral Dissertations

"Room temperature ionic liquids (RTILs) have received substantial interest as nonaqueous electrolytes in lithium ion- and metal-air batteries in recent years due to their low volatility, non-flammability, wide liquid range, and thermal stability characteristics. Towards developing a new generation of high specific energy lithium ion batteries, a series of imidazolium and pyrrolidinium based ionic liquids were synthesized and explored as nonaqueous electrolytes in lithium-, lithium ion-, and lithium-air batteries. Pyrrolidinium-TFSI based ionic liquids have wide electrochemical stability (5.7 - 6.2 V vs Li/Li⁺); however, they show limited thermal stabilities and lithium cell discharge characteristics. TFSI-based ionic liquids are …

Discrete And Dynamic Population Models With Logistic Growth Rate, Sabrina Heike Streipert

Doctoral Dissertations

"The Beverton-Holt difference equation defines a discrete relation describing a population model. Considering periodic carrying capacity and periodic inherent growth rate, a population with seasonal changing life cycle and environment is reflected. The so-called periodically forced Beverton-Holt equation is investigated and its unique periodic solution is derived. This provides the first Cushing-Henson conjecture, while a counterexample proves that the classical second Cushing-Henson conjecture is not satisfied. Modifications of the conjecture are formulated. To extend the studies, the Beverton-Holt equation is investigated in the quantum calculus time setting. The existence of the globally attracting periodic solution of the Beverton-Holt q-difference …

On Testing Common Indices For Several Multi-Index Models: A Link-Free Approach, Xuejing Liu

Doctoral Dissertations

"To avoid the curse of dimensionality, and to help us better understand the structure of the high dimensional data, methods for dimension reduction are clearly called for. The common linear dimension reduction techniques for single population include principal component analysis (PCA) which is unsupervised in regression and supervised Partial Least Squares (PLS). Modern sufficient dimension reduction techniques, like the ones we consider, constitute a form of supervised linear dimension reduction which outperform PCA and PLS without the underlying model assumptions.

In practice, we often deal with situations where the same variables are being measured on objects from different groups, and …

Nano-Structured Materials For Energy Storage Applications, Dongxue Zhao

Doctoral Dissertations

"Hydrogen is a non-polluting and efficient energy carrier. One barrier to utilizing hydrogen is a reliable storage method. NaAlH₄ is the prototypical example of a complex metal hydride with high hydrogen storage capacities (~ 5.5 wt.%) and acceptable reaction temperatures of around 100⁰ when using catalyst. On decomposition of these complex hydrides, such as NaAlH₄, one is left with monohydride NaH. The kinetics of diffusion in the monohydrides is important because reversibility hinges on mass transport and the formation of [AlH₄]^- anions that must structurally coordinate with the alkali metal cation on hydrogen absorption. …

Microstructure And Geotechnical Properties Of St. Peter Sandstone In Clayton, Iowa, Amir Hossein Bagherieh

Doctoral Dissertations

"The St. Peter Sandstone is significantly different from the minerals and rocks which have been studied extensively in mining. It is brittle and characterized by an unusually high friction angle. On the other hand it is friable, and it is nearly cohesionless. The scarcity of the ground control techniques for this particular mining environment has created many difficulties for mine operators. This research aims to establish a fundamental understanding of the basic mechanical and strength properties of the St. Peter Sandstone for engineering design and scientific research. The specific objectives are 1) characterizing the strength of the St. Peter Sandstone, …

Efficient Cryptographic Primitives: Secure Comparison, Binary Decomposition And Proxy Re-Encryption, Feng Li

Doctoral Dissertations

”Data outsourcing becomes an essential paradigm for an organization to reduce operation costs on supporting and managing its IT infrastructure. When sensitive data are outsourced to a remote server, the data generally need to be encrypted before outsourcing. To preserve the confidentiality of the data, any computations performed by the server should only be on the encrypted data. In other words, the encrypted data should not be decrypted during any stage of the computation. This kind of task is commonly termed as query processing over encrypted data (QPED).

One natural solution to solve the QPED problem is to utilize fully …

Scattering Amplitudes In Flat Space And Anti-De Sitter Space, Savan Kharel

Doctoral Dissertations

We calculate gauge theory one-loop amplitudes with the aid of the complex shift used in the Britto- Cachazo-Feng-Witten (BCFW) recursion relations of tree amplitudes. We apply the shift to the integrand and show that the contribution from the limit of infinite shift vanishes after integrating over the loop momentum, with a judicious choice of basis for polarization vectors. This enables us to write the one-loop amplitude in terms of on-shell tree and lower-point one-loop amplitudes. Some of the tree amplitudes are forward amplitudes. We show that their potential singularities do not contribute and the BCFW recursion relations can be applied …

Social Fingerprinting: Identifying Users Of Social Networks By Their Data Footprint, Denise Koessler Gosnell

Doctoral Dissertations

This research defines, models, and quantifies a new metric for social networks: the social fingerprint. Just as one's fingers leave behind a unique trace in a print, this dissertation introduces and demonstrates that the manner in which people interact with other accounts on social networks creates a unique data trail. Accurate identification of a user's social fingerprint can address the growing demand for improved techniques in unique user account analysis, computational forensics and social network analysis.

In this dissertation, we theorize, construct and test novel software and methodologies which quantify features of social network data. All approaches and methodologies are …

Investigations Into Ambient Ionization Mechanisms: Electrospray Ionization And Direct Analysis In Real Time Mass Spectrometry, Stephen Colin Gibson

Doctoral Dissertations

Mass spectrometry (MS) is an important tool for chemical analyses. Despite the MS requirement for generation of analyte gas-phase ions, many ion source designs afford little-to-no fragmentation, allowing characterization of intact molecules. However, this does not assure that detected ions are representative of the analytes’ natural state. Ionization mechanisms are generally complex and rarely fully understood. Fundamental research into these mechanisms provides greater insight into the relationship between solution chemistry and mass spectra. Work herein addresses aspects of two ambient ionization mechanisms: electrospray ionization (ESI) and Direct Analysis in Real Time (DART).

Ions produced by ESI are dispersed into a …

Elucidating Fundamental Mechanisms In Focused Electron- And Ion-Beam Induced Synthesis, Carlos M. Gonzalez

Doctoral Dissertations

A focused electron beam deposition process (FEBID) coupled with in-situ infrared pulsed laser assist (LA-EBID) has been implemented for higher purity tungsten nanowires using W(CO)₆ [tungsten hexacarbonyl] as parent precursor gas. Nanowires made of Co from Co₂(CO)₈ [dicobalt octacarbonyl] and Pt from MeCpPtIVMe₃ [trimethyl methylcyclopentadienyl platinum] have also been realized by using inert focused ion beams of helium and helium and neon, respectively. In all cases, higher electrical conductivities, higher purities and larger grain sizes have been obtained when compared with preceding traditional additive edit techniques. These new approaches will make possible successful nanoscale direct-write …

Comparisons Of Point And Average Capillary Pressure - Saturation Functions For Porous Media, Samuel Clark Cropper

Doctoral Dissertations

The relationship between the volume of water occupying pores in soil or rock and its energy state is called the capillary pressure–saturation function. This is an important hydrogeologic property needed for modeling multiphase flow and transport. Standard methods used to determine capillary pressure–saturation behavior produce volume averaged functions rather than point functions. Average functions can produce erroneous simulations in flow models. Analytical expressions permit extraction of point functions from average functions, and predictions of average functions from point function parameters. These concepts are discussed in Chapter I.

Chapter II compares average and point functions from centrifugation of Berea sandstone, glass …

Neutron Scattering Studies Of Phosphate Proton Conductors, Amal Bajes Al-Wahish

Doctoral Dissertations

Proton ceramic fuel cells operating in the intermediate temperature range of 300-500 °C offer potentially revolutionary advantages over existing fuel cells because expensive noble metal catalysts would not be needed, and in situ reforming of liquid bio-fuels such as ethanol or methanol would be possible.The chief obstacle facing intermediate fuel cells is the lack of a suitable electrolyte in the operating temperature range. A good electrolyte is thermally and chemically stable, inexpensive, environmentally friendly, and has a proton conductivity on the order of 10^-2 S cm^-1 [Siemens per centimeter] at 400 °C. Acceptor-doped lanthanum orthophosphate is an …

Synthesis And Thermodynamic Analysis Of Volatile Beta-Diketone Complexes Of Select Lanthanides Via Gas-Phase Separations, Daniel Hanson

Doctoral Dissertations

Rapid separation techniques for fission and activation products have long been desired to supplant the slow solution-based methodologies currently used. In this work, rare earth elements were derivatized with β [beta]-diketones to synthesize rare earth complexes with high volatility suitable for gas-phase separations. Rare earth elements samarium and dysprosium were combined with hfac (1,1,1,5,5,5-hexafluoro-2,4-pentadione) and fod (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione) and analyzed using a gas-phase separation technique. Rare earth elements praseodymium and europium were combined with dpm (2,2,6,6-tetra-methyl-3,5-heptanedione) and similarly analyzed. Employing the data from the separations, the entropy (Δ [delta] S) and enthalpy (Δ [delta] H) of adsorption were evaluated mathematically based …

Nonlocal Polarization Interferometry And Entanglement Detection, Brian P. Williams

Doctoral Dissertations

At present, quantum entanglement is a resource, distributed to enable a variety of quantum information applications such as quantum key distribution, superdense coding, and teleportation. Necessarily, the distribution and characterization of entanglement is fundamental to its application. This dissertation details three research efforts to enable nonlocal entanglement detection, distribution, and characterization. Foremost of these efforts, we present the theory and demonstration of a nonlocal polarization interferometer capable of detecting entanglement and identifying Bell states statistically. This is possible due to the interferometer’s unique correlation dependence on the anti-diagonal elements of the density matrix, which have distinct bounds for separable states …

Photo-Switchable Control Of Membrane Properties Of Liposomes And Biochemical Processes, Andrew Michael Bayer

Doctoral Dissertations

Liposomes are promising agents for drug delivery. They have the ability to encapsulate therapeutic drugs, resulting in decreased toxicity and prolonged circulation time. However, many obstacles to achieving broad utility in liposomal drug delivery still exist, including the ability to control release of therapeutic drugs and modulate surface reactivity. A primary focus of this dissertation involves the development of synthetic photocleavable lipids for controlled release from membranes.

Phosphatidylcholine (PC) is a natural lipid that comprises the majority of structural membranes. It contributes heavily to the formation of lipid bilayers in cell membranes, and modifications to the bilayer can induce membrane …

Computational Studies For Optimization And Design Of Extracting Agents For Separation Of Lanthanides And Actinides, Deborah Andrea Penchoff

Doctoral Dissertations

Rare earths and actinides are of great interest given their varied applications in energy conversion and storage, such as in catalysis and batteries, and for advanced technological applications related to optical and magnetic properties (including electronics and automotive), amongst others. Many of the rare earth elements are considered endangered species due to their unique properties which have no clear alternatives that will maintain performance for important applications. The optimal approach is to find readily available alternatives for critical materials to ensure a certain standard of living and quality of life for future generations, but it is very likely that reusing …

Hi-Fidelity Simulation Of The Self-Assembly And Dynamics Of Colloids And Polymeric Solutions With Long Range Interactions, Mahdy Malekzadeh Moghani

Doctoral Dissertations

Modeling the equilibrium properties and dynamic response of the colloidal and polymeric solutions provides valuable insight into numerous biological and industrial processes and facilitates development of novel technologies. To this end, the centerpiece of this research is to incorporate the long range electrostatic or hydrodynamic interactions via computationally efficient algorithms and to investigate the effect of these interactions on the self-assembly of colloidal particles and dynamic properties of polymeric solutions. Specifically, self-assembly of a new class of materials, namely bipolar Janus nano-particles, is investigated via molecular dynamic simulation in order to establish the relationship between individual particle characteristics, such as …

Interactive Feature Selection And Visualization For Large Observational Data, Jingyuan Wang

Doctoral Dissertations

Data can create enormous values in both scientific and industrial fields, especially for access to new knowledge and inspiration of innovation. As the massive increases in computing power, data storage capacity, as well as capability of data generation and collection, the scientific research communities are confronting with a transformation of exploiting the advanced uses of the large-scale, complex, and high-resolution data sets in situation awareness and decision-making projects. To comprehensively analyze the big data problems requires the analyses aiming at various aspects which involves of effective selections of static and time-varying feature patterns that fulfills the interests of domain users. …

Dual Channel-Based Network Traffic Authentication, David Irakiza

Doctoral Dissertations

In a local network or the Internet in general, data that is transmitted between two computers (also known as network traffic or simply, traffic) in that network is usually classified as being of a malicious or of a benign nature by a traffic authentication system employing databases of previously observed malicious or benign traffic signatures, i.e., blacklists or whitelists, respectively. These lists typically consist of either the destinations (i.e., IP addresses or domain names) to which traffic is being sent or the statistical properties of the traffic, e.g., packet size, rate of connection establishment, etc. The drawback with the list-based …

Topology Dependence Of Ppm-Based Internet Protocol Traceback Schemes, Ankunda R. Kiremire

Doctoral Dissertations

Multiple schemes that utilize probabilistic packet marking (PPM) have been proposed to deal with Distributed Denial of Service (DDoS) attacks by reconstructing their attack graphs and identifying the attack sources.

In the first part of this dissertation, we present our contribution to the family of PPM-based schemes for Internet Protocol (IP) traceback. Our proposed approach, Prediction-Based Scheme (PBS), consists of marking and traceback algorithms that reduce scheme convergence times by dealing with the problems of data loss and incomplete attack graphs exhibited by previous PPM-based schemes.

Compared to previous PPM-based schemes, the PBS marking algorithm ensures that traceback is possible …

Studies Of Angular Correlations Of Jets With The Atlas Detector, Rajivalochan Subramaniam

Doctoral Dissertations

The strong force is one of the four fundamental forces and its strength is given by the coupling constant αs. The theory that describes the strong interaction is Quantum Chromodynamics (QCD) and it explains the interactions between quarks and gluons. The strong coupling constant is the only free parameter in the QCD Lagrangian if the quark masses are fixed. Determinations of αs provide direct tests of perturbative QCD calculations. The collimated sprays of particles originating from the quark and gluon interactions are called jets. The ratio of jet cross sections are sensitive to α s and are …

Growth, Structure, Electronic And Transport Properties Of Yttrium Disilicide Nanowires, Saban Mustafa Hus

Doctoral Dissertations

The electronic properties of low-dimensional materials deviate significantly from their bulk counterparts. Especially in quasi one-dimensional (1D) materials, a small number of structural defects can lead to strong electron localization. Electrons may also display unusual collective behavior in 1D. As integrated circuits continue to shrink in size, there is an increasing need for understanding and possibly manipulating electronic transport in quasi 1D materials. Here, we focus on electrical transport in self-assembled YSi₂ [yttrium disilicide] nanowires on Si(001). Being just a few atoms wide, these nanowires are one of the closest experimental realizations of a 1D conductor. YSi₂ nanowires …

Composition Dependence Of The Flory-Huggins Interaction Parameter In Polymer Blends: Structural And Thermodynamic Calculations, Travis H. Russell

Doctoral Dissertations

Flory-Huggins Theory has been the basis for understanding polymer solvent and blended polymer thermodynamics for much of the last 60 years. Within this theory, a parameter (χ) [chi] was included to quantify the enthalpic energy of dispersion between distinct components. Thin film self-assembly of polymer melts and block copolymers depends critically on this parameter, and in application, χ has generally been assumed to be independent of the concentrations of the individual components of the system. However, Small-Angle Neutron Scattering data on isotopic polymer blends, such as polyethylene and deuterated polyethylene, have shown a roughly parabolic concentration dependency for …