Digital Commons Network^™

Hardware Implementation Of Multiple-Input Multiple-Output Transceiver For Wireless Communication, Bing Han

Doctoral Dissertations

"This dissertation proposes an efficient hardware implementation scheme for iterative multi-input multi-output orthogonal frequency-division multiplexing (MIMO-OFDM) transceiver. The transmitter incorporates linear precoder designed with instantaneous channel state information (CSI). The receiver implements MMSE-IC (minimum mean square error interference cancelation) detector, channel estimator, low-density parity-check (LDPC) decoder and other supporting modules. The proposed implementation uses QR decomposition (QRD) of complex-valued matrices with four co-ordinate rotation digital computer (CORDIC) cores and back substitution to achieve the best tradeoff between resource and throughput. The MIMO system is used in field test and the results indicate that the instantaneous CSI varies very fast in …

Investigation Of Fluids Flow Behavior In Nano-Scale Channels By Using Optic Imaging System, Qihua Wu

Doctoral Dissertations

"Tight gas and shale gas reservoirs are characterized to have small pores with diameters in nanometer (nm) range. The physics of fluid flow in nanopores is poorly understood. Knowing the fluid flow behavior in the nano-range channels is of major importance for stimulation design, gas production optimization and calculations of the relative permeability of gas in tight shale gas systems. In this work, a lab-on-chip approach for direct visualization of the fluid flow behavior in nano-scale channels was developed using an advanced epi-fluorescence microscopy method combined with a nano-fluidic chip. The nanofluidic chips with different dimensions were designed and fabricated. …

Hardware Integration Of Ultracapacitor Based Energy Storage To Provide Grid Support And To Improve Power Quality Of The Distribution Grid, Deepak Somayajula

Doctoral Dissertations

"Grid integration of distributed energy resources (DERs) is increasing rapidly. Integration of various types of energy storage technologies like batteries, ultracapacitors (UCAPs), superconducting magnets and flywheels to support intermittent DERs, such as solar and wind, in order to improve their reliability is becoming necessary. Of all the energy storage technologies UCAPs have low energy density, high power density and fast charge/discharge characteristics. They also have more charge/discharge cycles and higher terminal voltage per module when compared to batteries. All these characteristics make UCAPs ideal choice for providing support to events on the distribution grid which require high power for short …

Graphite Aerogels And The Formation Mechanism Of Unusual Micron-Sized Rod And Helical Structures, Clarissa Ann Wisner

Doctoral Dissertations

"Pyrolysis at 800 ºC under argon has shown that polyimide (PI), polyacrylonitrile (PAN), polydicyclopentadiene (DCPD) and polybenzoxazine (PBO) aerogels are all viable alternatives to traditional resorcinol-formaldehyde (RF) aerogels as precursors to amorphous carbon aerogels. Subsequent high temperature pyrolysis at 2300 ºC of such carbon aerogels under helium has shown that amorphous carbon from PI and PBO yields the highest degree of graphitization, whereas from RF aerogels yields the lowest.

Those two types of graphite aerogels include also a high concentration of micron-size columnar and helical (screw-like) structures, whose formation is favored by macroporosity and high nitrogen retention in the 800 …

Multiple Security Domain Nondeducibility In Cyber-Physical Systems, Gerry W. Howser

Doctoral Dissertations

"Cyber-physical Systems (CPS) present special problems for security. This dissertation examines the cyber security problem, the physical security problem, the security problems presented when cyber systems and physical systems are intertwined, and problems presented by the fact that CPS leak information simply by being observed. The issues presented by applying traditional cyber security to CPS are explored and some of the shortcomings of these models are noted. Specific models of a "drive-by-wire'' automobile connected to a road side assistance network, a "Stuxnet type'' attack, the smart grid, and others are presented in detail.

The lack of good tools for CPS …

Performance Assessment Of Capture Zones Generated By Pv-Powered Pump And Treat Systems, Yovanna Cortes Di Lena

Doctoral Dissertations

"Pump and treat (P&T) is a technology that has been extensively used to remove and/or contain contaminated groundwater. Hydraulic containment of contaminants is accomplished by generating capture zones through pumping of groundwater. An appropriate delineation of capture zones is necessary to design an effective P&T system. P&T systems conventionally operate continuously to achieve steady-state capture zones, which require significant amounts of energy. The use of renewable energies to meet power demands of remedial systems may reduce a project's carbon dioxide emissions. The hydraulic effectiveness of a photovoltaic (PV) powered P&T system without energy storage was characterized using data collected at …

Precambrian Evolution Of The Salalah Crystalline Basement From Structural Analysis And 40Ar/39Ar Geochronology, Hanadi Abulateef Al-Doukhi

Doctoral Dissertations

"The Salalah Crystalline Basement (SCB) is the largest Precambrian exposure in Oman located on the southern margin of the Arabian Plate at the Arabian Sea shore. This work used remote sensing, detailed structural analysis and the analysis of ten samples using ⁴⁰Ar/³⁹Ar age dating to establish the Precambrian evolution of the SCB by focusing on its central and southwestern parts. This work found that the SCB evolved through four deformational events that shaped its final architecture: (1) Folding and thrusting event that resulted in the emplacement of the Sadh complex atop the Juffa complex. This event resulted …

Seismic Anisotropy And Mantle Flow Beneath Africa And Arabia, Ahmed Abdalla Elsheikh

Doctoral Dissertations

"In spite of numerous studies, the mechanisms for the rifting, uplifting, and volcanism on the African plate remain enigmatic. The most popular hypotheses proposed for explaining these tectonic phenomena involve edge-driven small-scale mantle convection and the thermal or dynamic effects of one or more mantle plumes. In this study we use continental scale shear-wave splitting (SWS) measurements to provide additional constraints on the various models of rifting, uplifting, and volcanism of the Cameroon Volcanic Line (CVL) and the Arabian plate. The splitting of P-to-S converted phases at the core-mantle boundary on the receiver side (XKS including PKS, SKKS, and SKS) …

Sparse Nonlinear Optimization For Signal Processing And Communications, Zengli Yang

Doctoral Dissertations

"This dissertation proposes three classes of new sparse nonlinear optimization algorithms for network echo cancellation (NEC), 3-D synthetic aperture radar (SAR) image reconstruction, and adaptive turbo equalization in multiple-input multiple-output (MIMO) underwater acoustic (UWA) communications, respectively.

For NEC, the proposed two proportionate affine projection sign algorithms (APSAs) utilize the sparse nature of the network impulse response (NIR). Benefiting from the characteristics of l₁-norm optimization, affine projection, and proportionate matrix, the new algorithms are more robust to impulsive interferences and colored input than the conventional adaptive algorithms.

For 3-D SAR image reconstruction, the proposed two compressed sensing (CS) approaches exploit the …

Speciation Dynamics Of An Agent-Based Evolution Model In Phenotype Space, Adam David Scott

Doctoral Dissertations

"This dissertation is an exploration of phase transition behavior and clustering of populations of organisms in an agent-based model of evolutionary dynamics. The agents in the model are organisms, described as branching-coalescing random walkers, which are characterized by their coordinates in a two-dimensional phenotype space. Neutral evolutionary conditions are assumed, such that no organism has a fitness advantage regardless of its phenotype location. Lineages of organisms evolve by limiting the maximum possible offspring distance from their parent(s) (mutability, which is the only heritable trait) along each coordinate in phenotype space. As mutability is varied, a non-equilibrium phase transition is shown …

Synthesis Of Radioactive And Nonradioactive Nanostructures Through Radiolytic And Wet Chemistry, Jessika Viviana Rojas Marin

Doctoral Dissertations

"In this work the synthesis of non radioactive and radioactive nanoparticles (NPs) through radiolytic and wet chemistry was studied. Non radioactive NPs of rhenium, iridium, and rhodium were synthesized from aqueous solutions containing the metal salt precursors by gamma irradiation. The solutions were irradiated to generate reducing species that led to the nucleation and growth of the nanoparticles. Amorphous rhenium oxide nanoparticles with average sizes ranging from 10 nm to 55 nm were obtained. Metallic iridium and rhodium nanoparticles were produced in polyvinyl-pyrrolidone (PVP) having narrow particle size distributions and average particle sizes from 2 nm to 6 nm. The …

The Structure And Properties Of Ternary Zinc Phosphate Glasses For Optical Applications, Charmayne Elizabeth Smith

Doctoral Dissertations

"This dissertation focuses on the properties and structures of ternary zinc phosphate glasses that have recently been investigated as substrates for femto-second (fs) laser writing. Although these glasses have potential for use as optical substrates, their poor chemical properties limit their applications. In this work, ternary zinc phosphate glasses were studied to find compositions with enhanced chemical durability and the properties and structures of the investigated glasses are reported.

Paper 1 and Paper 2 include the first systematic studies of the properties, structures of zinc aluminophosphate (ZAP) glasses and phase relationships in the ZnO-Al₂O₃-P₂O₅ system, respectively. Adding alumina to a …

Turbo Equalization For Multiple-Input Multiple-Output (Mimo) Wireless Communication Systems, Longbao Wang

Doctoral Dissertations

"This dissertation investigates both of the frequency domain and time domain turbo equalization with multiple-input multiple-output (MIMO) fading channels for radio frequency and underwater acoustic communications. First, a low complexity frequency domain turbo equalization (FDTE) is proposed for the MIMO systems with zero padding (ZP) or cyclic prefix (CP) inserted between the transmitted data blocks and its performance is tested on the real-world UWA communications experiments.

Second, as high speed communication system requires efficient bandwidth usage and power consumption, CP or ZP is not transmitted as auxiliary information. An inter-block interference cancelation and CP reconstruction algorithm is developed to re-arrange …

Far-Field Prediction Using Only Magnetic Near-Field Scanning And Modeling Delay Variations In Cmos Digital Logic Circuits Due To Electrical Disturbances In The Power Supply, Xu Gao

Doctoral Dissertations

"The first topic of this dissertation is far-field prediction using only magnetic near-field scanning. Near-field scanning has been used extensively for the far-field estimation of antennas. Applied to electromagnetic compatibility (EMC) problems, near-field scanning has been used to estimate emissions from both integrated circuits (ICs) and printed circuit boards (PCBs). Interest in applying far-field predictions using near-field to EMI/EMC problems has recently grown. To predict the far-field emissions from a PCB in the top half space, the near-field data on a planar surface above PCB usually is sufficient. However, near-field measurement on only one planar surface may not be enough …

Maximum Crosstalk Estimation And Modeling Of Electromagnetic Radiation From Pcb/High-Density Connector Interfaces, Matthew Scott Halligan

Doctoral Dissertations

"This dissertation explores two topics pertinent to electromagnetic compatibility research: maximum crosstalk estimation in weakly coupled transmission lines and modeling of electromagnetic radiation resulting from printed circuit board/high-density connector interfaces. Despite an ample supply of literature devoted to the study of crosstalk, little research has been performed to formulate maximum crosstalk estimates when signal lines are electrically long. Paper one illustrates a new maximum crosstalk estimate that is based on a mathematically rigorous, integral formulation, where the transmission lines can be lossy and in an inhomogeneous media. Paper two provides a thorough comparison and analysis of the newly derived maximum …

The Role Of Potential Antioxidant In Medicinal Drug-Induced Oxidative Stress, Weili Fan

Doctoral Dissertations

"Most medicinal drugs have adverse effects. Among the most commonly used of these drugs are several types, known as "oxidative drugs". These are believed to cause adverse effects that induce oxidative stress, an imbalance of generation and detoxification of reactive oxygen species. So it is a reasonable assumption that the antioxidant might alleviate the toxicity induced by these drugs. N-acetylcysteine (NAC), a synthetic thiol, is a free-radical scavenger and a precursor of glutathione (the main endogenous antioxidant). However, the negative charge of NAC at physiological pH limits its bioavailability. N-acetylcysteineamide (NACA) is neutral in charge and is believed to have …

Cross-Layer Schemes For Performance Optimization In Wireless Networks, Quanmin Ye

Doctoral Dissertations

"Wireless networks are undergoing rapid progress and inspiring numerous applications. As the application of wireless networks becomes broader, they are expected to not only provide ubiquitous connectivity, but also support end users with certain service guarantees.

End-to-end delay is an important Quality of Service (QoS) metric in multihop wireless networks. This dissertation addresses how to minimize end-to-end delay through joint optimization of network layer routing and link layer scheduling. Two cross-layer schemes, a loosely coupled cross-layer scheme and a tightly coupled cross-layer scheme, are proposed. The two cross-layer schemes involve interference modeling in multihop wireless networks with omnidirectional antenna. In …

Synthesis And Properties Of Transition-Metal Arsenide Nanostructures: From Superparamagnetism To Superconductivity, Prachi Desai

Doctoral Dissertations

"This dissertation study focuses on developing new protocols for synthesis of nanostructured transition-metal pnictides including superconducting LiFeAs and studying their structure- property relationship. Nanostructured materials are known to differ in properties compared to their bulk counterparts owing to enhanced surface area and increased packing efficiency in devices. Synthetic chemistry skills and nanofabrication techniques like wet chemistry, electrodeposition, solvothermal, hydrothermal and lithography, are extremely useful for creating nanostructures of these functional materials. This is a challenging task simply because maintaining the phase composition same as that of the bulk material along with achieving nanostructures (nanoparticles, nanowires, nanopillars etc.) simultaneously is not …

Identifying And Overcoming The Barriers To Sustainable Construction, Cristin Szydlik

Doctoral Dissertations

"Sustainable construction has become increasingly more prevalent over the last decade. All federal and most state government buildings are mandated to achieve Leadership in Energy and Environmental Design (LEED) certification (at the silver level at a minimum). Although sustainable construction is increasingly more common, there are still barriers to the successful completion of a sustainable project, specifically with regards to projects achieving LEED certification. There are still holes in the guidance on how to successfully achieve LEED certification. Even though government agencies have mandated LEED certification, the existing barriers are preventing buildings from achieving certification, which can delay the building …

Emission Source Microscopy For Electromagnetic Interference Source Localization, Pratik Rajesh Maheshwari

Doctoral Dissertations

"For complex and large systems with multiple sources, it is often difficult to localize the sources of radiation. Near-field electromagnetic scanning is used often for root-cause diagnosis by determining field distribution close to the PCB. In the near-field, the evanescent waves are dominant, which may lead to the misinterpretation of them being the dominant sources contributing to the far-field. Another limitation of near-field scanning is that the probe may not be able to access all locations near the PCB due to the complex geometry and high component density. Two-dimensional synthetic aperture radar is a well-known technique used for antenna diagnostic …

Improving The Oxidation Resistance Of Diboride-Based Ceramics, Maryam Kazemzadeh Dehdashti

Doctoral Dissertations

"Oxidation behavior has restricted the development of ZrB₂-based ceramics for aerospace and hypersonic flight vehicles applications. The research presented in this dissertation focuses on the effect of transition metal (TM) additives on oxidation behavior of ZrB₂ ceramics. In the first stage of the research, the effect of Nb additions on the morphology of the oxide particles and stability of the protective B₂O₃ glassy layer, which formed on the top surface during oxidation, was investigated. Addition of Nb increased the thickness of the glassy layer and, as a result, improved the oxidation resistance of ZrB₂ after oxidation at 1500⁰C. Next, the …

Plant Uptake Of Environmental Contaminants: Applications In Phytoscreening, Matthew Alan Limmer

Doctoral Dissertations

"Plants interact directly with their surroundings, extracting nutrients and water from the subsurface to support growth and development of the plant. Through the roots, plants also exude and uptake numerous chemicals. Many of the pathways can also be used by environmental contaminants to be translocated to above ground plant tissues. Such uptake of contaminants has proven useful in remediation and phytoscreening - the use of plants to delineate contaminant plumes. Sampling of trees at contaminated field sites has been used to identify areas of groundwater contaminated with a variety of chlorinated solvents. The use of plants as contaminant biosensors requires …

Investigating And Modeling Tar-Mats In A Kuwaiti Carbonate Reservoir And Their Role In Understanding Oil Reserves And Recovery Economics, Abdullah Owidah Almansour

Doctoral Dissertations

"Tar-mat columns exist in many carbonate reservoirs in the Middle East. Historically, tar-mats have been thought to impede primary oil extraction, thus necessitating further improved oil recovery (IOR) technology applications. However, this research considers tar-mats as potential sources for unlocking extremely difficult crude oil, less than 5 ⁰API. The main objective of the study was to understand the qualitative physical and chemical properties of extremely viscous tar-mat oil and the quantitative potential of tar-mats to extract difficult oil.

The physical and chemical geneses of the tar-mat oil were analyzed utilizing several experimental geochemical techniques, including rock evaluation pyrolysis, liquid extracts …

Phosphate-Doped Borosilicate Enamel Coating Used To Protect Reinforcing Steel From Corrosion, Xiaoming Cheng

Doctoral Dissertations

"Phosphate-doped sodium borosilicate glasses were developed for enamel coatings to provide corrosion protection for reinforcing steel in concrete. Phosphates have low solubilities in borosilicate glasses, generally less than about 4 mol%, and are incorporated mainly as isolated PO₄^3- and P₂O₇^4- anions, along with some borophosphate bonds. With the addition of P₂O₅, the silicate network is repolymerized and tetrahedral borates are converted to trigonal borates, because the phosphate anions scavenge sodium ions from the borosilicate network. The addition of Al₂O₃ significantly increases the solubility of P₂O …

Modeling And Estimation Of Crosstalk Across A Channel With Multiple, Non-Parallel Coupling And Crossings Of Multiple Aggressors In Practical Pcbs, Arun Reddy Chada

Doctoral Dissertations

"In Section 1, the focus is on alleviating the modeling challenges by breaking the overall geometry into small, unique sections and using either a Full-Wave or fast equivalent per-unit-length (Eq. PUL) resistance, inductance, conductance, capacitance (RLGC) method or a partial element equivalent circuit (PEEC) for the broadside coupled traces that cross at an angle. The simulation challenge is resolved by seamlessly integrating the models into a statistical simulation tool that is able to quantify the eye opening at BERs that would help electrical designers in locating crosstalk sensitive regions in the high speed backplane channel designs.

Section 2 investigates the …

Effect Of Solid Solutions And Second Phases On The Thermal Conductivity Of Zirconium Diboride Ceramics, Gregory John Kenneth Harrington

Doctoral Dissertations

"The research presented in this dissertation is focused on the thermal conductivity (k) of ZrB₂ ceramics. The goal was to develop a better understanding of how various solid solutions and second phases affect the thermal and electrical transport in ZrB₂, with a focus on the effect of C, W, and ZrC. The first study showed C additions improved densification and it was proposed that the reduction of boria was the impetus for this result. Boron carbide was formed by the reaction of excess C with reduced B and its formation was mitigated by the addition of ZrH …

Femtosecond Laser Micro-Machined Optical Fiber Based Embeddable Strain And Temperature Sensors For Structural Monitoring, Armadeep Kaur

Doctoral Dissertations

"Structural monitoring technology is becoming increasingly important for managing all types of structures. Embedding sensors while constructing new structures or repairing the old ones allows for continual monitoring of structural health thus giving an estimate of remaining utility. Along with being embeddable, miniaturized sensors that are easy to handle are highly sought after in the industry where in-situ monitoring is required in a harsh environment (corrosive atmosphere, high temperatures, high pressure etc.).

This dissertation demonstrates the use of femtosecond laser-fabricated Fabry-Perot interferometer (FPI) based optical fiber sensors for embedded applications like structural health monitoring. Two types of Fabry-Perot interferometer sensors, …

Thermophysical Properties Of Reaction Processed Zirconium Diboride, Jason Michael Lonergan

Doctoral Dissertations

"This dissertation focuses on the thermophysical properties of high purity zirconium diboride ceramics. These ceramics have shown promise for potential applications such as leading edge materials for next generation hypersonic vehicles. The overall goal of this work was to improve the understanding of the thermal properties and maximize the thermal conductivity of ZrB₂. Four main areas were investigated in this work. First, the sintering kinetics and the intrinsic thermal properties of reaction processed ZrB₂ were studied and compared to ZrB₂ produced by hot pressing commercial powders. The reaction process produced ceramics with higher thermal conductivity and …

Dissolution Behavior Of Phosphate Glasses, Li Na Ma

Doctoral Dissertations

"The solubility of phosphate glasses in aqueous solutions can be tailored through compositional control to obtain a wide range of ion release rates required for a variety of applications. The principal objective of this dissertation is to advance the understanding of the dissolution behavior of phosphate glasses in aqueous environments.

Two families of glasses, sodium-iron phosphate (NFP) glasses and sodium-calcium phosphate (NCP) glasses, were evaluated. The dissolution behavior depends on the phosphate anions that constitute the glass structure and the associated metal (Me) cations. The phosphate glass structure, defined by the distribution and average size of phosphate anions and depending …

Study And Pilot Test On A Novel Eor Method - Coupling Ppg Conformance Control And Surfactant Flooding, Farag Awadh Muhammed

Doctoral Dissertations

"The interest in enhanced oil recovery (EOR) methods has re-emerged in recent years; however, significant challenges remain for the widespread deployment of these methods. One major downside to the successful application of EOR technologies in mature reservoirs is conformance problems (e.g. heterogeneity). To mitigate these problems, a novel EOR method which couple preformed particle gel (PPGs) conformance treatment with traditional surfactant flooding in one process is introduced.

This dissertation provides a comprehensive study for the proposed method. A series of laboratory tests were carried out to understand the chemical interaction between PPGs and surfactants. A new method to evaluate PPGs …