Engineering Commons^™

Directed Differentiation And Characterization Of Spinal V3 Interneurons From Mouse Embryonic Stem Cells, Hao Xu

McKelvey School of Engineering Theses & Dissertations

Neuronal populations involved in locomotion controlling central pattern generators within the spinal cord hold great potential for spinal cord injury therapy. Spontaneous recovery in rodent models suggests that a population that can reorganize around an injury site could be useful for functional recovery therapeutics after spinal cord injury. The glutamatergic, commissural, long-extending V3 interneurons shown to balance locomotor rhythm regularity and robustness within central pattern generators in vivo are both an ideal population for spinal cord injury therapeutics and a vital population to study as a part of locomotor circuitry. Unfortunately, due to the scarcity of these cells in the …

Spectrum Management Using Markov Decision Processes, John Leo Meier

McKelvey School of Engineering Theses & Dissertations

Abstract: The advent of cognitive radio technology has enabled dramatically more options in the use of RF spectrum, allowing multiple transmitters to effectively share spectrum in ways that were previously unavailable (either due to technical limitations or regulatory restrictions). In this dissertation, we investigate approaches to managing RF spectrum use, with a focus on combining multiple control decisions in a mutually beneficial manner.

Our approach to making spectrum management decisions is grounded in Markov decision theory, which has a rich formal foundation and is frequently used to guide decision making in other disciplines. Here, we develop a set of Markov …

Synthesis Of Clickable Poly(Ethylene Glycol) Derivatives For Fabrication Of Modular Microsphere-Based Scaffolds To Promote Vascularization, Peter Nguyen

McKelvey School of Engineering Theses & Dissertations

Vascularization plays an important role in supporting transplanted tissues and cells in tissue engineering applications. Most tissues require access to blood vessels for the delivery of oxygen and nutrients, as well as the removal of carbon dioxide and cellular waste products. Without an adequate blood supply, cells within tissue-engineered constructs and scaffolds lose viability and fail to perform their intended functions. The goal of this dissertation was to design scaffolds that can promote vascularization of biomaterial implants for biomedical applications. In order to accomplish this goal, clickable poly(ethylene glycol) (PEG) derivatives were synthesized in order to fabricate modular microsphere-based scaffolds …

Application Of Wray-Agarwal Model To Turbulent Flow In A 2d Lid-Driven Cavity And A 3d Lid-Driven Box, Hakop J. Nagapetyan

McKelvey School of Engineering Theses & Dissertations

In this thesis, various turbulence models are used for simulating internal vortical flow, both turbulent and laminar, with large recirculation by considering the flow in a 2-D lid-driven square cavity and a 3-D lid driven cubic box. The accuracy of the newly developed Wray-Agarwal (WA) one equation turbulence model is compared against two well-known industry standard turbulence models; the Spalart-Allmaras (SA) and the Shear-Stress-Transport (SST) k-ω models. The simulations are performed by numerically solving the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with WA, SA and SST k-ω models and comparing the results with the available experimental data and Large Eddy …

Entry Flow And Heat Transfer Of Laminar And Turbulent Forced Convection Of Nanofluids In A Pipe And A Channel, Yihe Huang

McKelvey School of Engineering Theses & Dissertations

This thesis presents a numerical investigation of laminar and turbulent fluid flow and convective heat transfer of nanofluids in the entrance and fully developed regions of flow in a channel and a pipe. In recent years, nanofluids have attracted attention as promising heat transfer fluids in many industrial processes due to their high thermal conductivity. Nanofluids consist of a suspension of nanometer-sized particles of higher thermal conductivity in a liquid such as water. The thermal conductivity of nanoparticles is typically an order-of-magnitude higher than the base liquid, which results in a significant increase in the thermal performance of the nanofluid …

Optimization Of Blalock-Taussig Shunt And Anastomotic Geometry For Vascular Access Fistula Using A Genetic Algorithm, Guangyu Bao

McKelvey School of Engineering Theses & Dissertations

Blalock-Taussig (BT) shunts are used for defects that affect the flow of blood from the right ventricle, through the pulmonary artery, and to the lungs. Arteriovenous (AV) fistula is one type of vascular access which is a surgically created vein used to remove and return blood during hemodialysis. Plastic grafts used in the above two reconstructions may result in areas of non-physiologic flow in the grafts leading to risk of stenosis (blocked area) and thrombosis, which is the single major cause for access morbidity. The focus of this thesis is to study BT shunts and anastomoses models using Computational Fluid …

Gold Nanostructures For Sensing And Functional Bioimaging, Maximilian Y. Fei

McKelvey School of Engineering Theses & Dissertations

Gold nanostructures offer an extremely promising path forward in the fields of imaging and sensing because of their unique optical and chemical properties. Here, we demonstrate that plasmonic nanostructures can be employed as nanoscale transducers to monitor the growth and phase transitions in ultrathin polymer films. In particular, gold nanorods with high refractive index sensitivity (~150 nm / refractive index unit (RIU)) were employed to probe the growth and swelling of polyelectrolyte multilayers (PEM). By comparing the wavelength shift and extinction intensity of the localized surface plasmon resonance (LSPR) of the gold nanorods coated with PEM in air and water, …

Photonic Molecules Formed By Ultra High Quality Factor Microresonator For Light Control, Bo Peng

McKelvey School of Engineering Theses & Dissertations

Whispering-gallery-mode (WGM) optical microresonators with micro-scale mode volumes and high quality factors have been widely used in different areas ranging from sensing, quantum electrodynamics (QED), to lasing and optomechanics. Due to the ultra-high Q and the tight spatial confinement, the cavity provides high intra-cavity field intensity and long interaction time, which enhances the interaction between light and materials. This feature makes WGM microresonator a great candidate for low-threshold nonlinear processes, cavity optomechanics, signal processing, and sensor with ultra-high sensitivity. Also, modification of the modes in these resonators has been of considerable interest for their potential applications and underlying physics. Two …

Discrete And Continuous Sparse Recovery Methods And Their Applications, Zhao Tan

McKelvey School of Engineering Theses & Dissertations

Low dimensional signal processing has drawn an increasingly broad amount of attention in the past decade, because prior information about a low-dimensional space can be exploited to aid in the recovery of the signal of interest. Among all the different forms of low di- mensionality, in this dissertation we focus on the synthesis and analysis models of sparse recovery. This dissertation comprises two major topics. For the first topic, we discuss the synthesis model of sparse recovery and consider the dictionary mismatches in the model. We further introduce a continuous sparse recovery to eliminate the existing off-grid mismatches for DOA …

Interfacial Chemistry Of Trace Elements At Mineral Surfaces In Engineered Water Systems, Lin Wang

McKelvey School of Engineering Theses & Dissertations

This thesis research consists of two independent research projects that both studied interfacial chemical processes affecting trace elements at mineral surfaces.

The objectives of Project 1 were to 1) quantify the impact of water chemistry on As(III) adsorption on lepidocrocite, 2) develop a surface complexation model to describe equilibrium As(III) and As(V) adsorption to lepidocrocite and 3) elucidate the mechanism of Fe(II)-mediated As(III) oxidation at the lepidocrocite-water interface. Arsenic is a regulated element that can be found at high concentrations in groundwater resources that are used as drinking water sources. Iron (oxyhydr)oxides are one of the most abundant groups of …

Statistical Nested Sensor Array Signal Processing, Keyong Han

McKelvey School of Engineering Theses & Dissertations

Source number detection and direction-of-arrival (DOA) estimation are two major applications of sensor arrays. Both applications are often confined to the use of uniform linear arrays (ULAs), which is expensive and difficult to yield wide aperture. Besides, a ULA with N scalar sensors can resolve at most N − 1 sources. On the other hand, a systematic approach was recently proposed to achieve O(N 2 ) degrees of freedom (DOFs) using O(N) sensors based on a nested array, which is obtained by combining two or more ULAs with successively increased spacing.

This dissertation will focus on a fundamental study of …

Potential-Flow Inflow Model Including Wake Distortion And Contraction, Jianzhe Huang

McKelvey School of Engineering Theses & Dissertations

Dynamic wake models have been used in real-time flight simulations for over thirty years. The models have evolved from the earliest, three-degree-of-freedom models (derived from momentum theory) to full finite-state models derived from potential flow theory by a formal Galerkin method. These models are widely used in industry, but still have some drawbacks that need to be remedied. These drawbacks include: 1.) lack of good convergence both on the disk and off the disk (one can use one or the other but not both), 2.) poor results downstream in the limit of shallow skew angles, 3.) poor convergence inside of …

Effects Of Biomass Moisture Content On Volatile Flame Length During Cofiring With Coal, Matthew Pollard

McKelvey School of Engineering Theses & Dissertations

Cofiring biomass with coal can contribute to meeting Renewable Portfolio Standards (RPS) and reduce pollutant emissions. The physical characteristics and composition of biomass can vary significantly, which can affect the combustion characteristics. When cofiring biomass with coal, these differences can impact the structure of the volatile flame, the region where combustion of volatiles dominates. The length and location of the volatile flame is important to flame stability and determines the location and extent of volatile release. This has an effect on pollutant emissions, such as NOx (nitrogen oxides). Previously, the effects of parameters such as cofiring ratio, particle size, and …

Genetic Algorithm Based Optimization Of Baffle Positions In A Forward Osmosis Draw Channel, James Koch

McKelvey School of Engineering Theses & Dissertations

Forward Osmosis (FO) driven asymmetric membrane filtration is a developing technology which shows promise for seawater desalination and wastewater treatment. Due to the fact that asymmetric membranes are widely used in conjunction with this technology, internal concentration polarization (ICP), a flow-entrainment effect occurring within such membranes, is a significant if not dominant source of overall osmotic pressure loss across the membrane. Accurate modeling of ICP effects is therefore very critical for accurate Computational Fluid Dynamic (CFD) modeling of asymmetric membranes. A related, dilutive effect known as external concentration polarization (ECP) also develops on both the rejection and draw sides of …

Integration Of Alignment And Phylogeny In The Whole-Genome Era, Hongtao Sun

McKelvey School of Engineering Theses & Dissertations

With the development of new sequencing techniques, whole genomes of many species have become available. This huge amount of data gives rise to new opportunities and challenges. These new sequences provide valuable information on relationships among species, e.g. genome recombination and conservation. One of the principal ways to investigate such information is multiple sequence alignment (MSA). Currently, there is large amount of MSA data on the internet, such as the UCSC genome database, but how to effectively use this information to solve classical and new problems is still an area lacking of exploration. In this thesis, we explored how to …

Light Controlling At Subwavelength Scales In Nanophotonic Systems: Physics And Applications, Yuecheng Shen

McKelvey School of Engineering Theses & Dissertations

The capability of controlling light at scales that are much smaller than the operating wave-length enables new optical functionalities, and opens up a wide range of applications. Such a capability is out of the realm of conventional optical approaches. This dissertation aims to explore the light-matter interactions at nanometer scale, and to investigate the novel scien-tific and industrial applications. In particular, we will explain how to detect nanoparticles using an ultra-sensitive nano-sensor; we will also describe a photonic diode which gener-ates a unidirectional flow of single photons; Moreover, in an one-dimensional waveguide QED system where the fermionic degree of freedom …

Strategies For Increasing The Applicability Of Biological Network Inference, Ezekiel John Maier

McKelvey School of Engineering Theses & Dissertations

The manipulation of cellular state has many promising applications, including stem cell biology and regenerative medicine, biofuel production, and stress resistant crop development. The construction of interaction maps promises to enhance our ability to engineer cellular behavior. Within the last 15 years, many methods have been developed to infer the structure of the gene regulatory interaction map from gene abundance snapshots provided by high-throughput experimental data. However, relatively little research has focused on using gene regulatory network models for the prediction and manipulation of cellular behavior. This dissertation examines and applies strategies to utilize the predictive power of gene network …

Development Of 13c Fingerprint Tool And Its Application For Exploring Carbon And Energy Metabolism In Cyanobacterium Synechocystis Sp. Pcc 6803, Le You

McKelvey School of Engineering Theses & Dissertations

Cyanobacteria are important microbial cell factories that are widely used in the biotechnology filed nowadays. They can use light as the sole energy source to fix CO2, accumulate biomass, and produce various valuable bio-products. Engineered cyanobacterial species can uptake nutrients from wastes to further reduce the cost. Recently, it is reported that cyanobacteria will provide much higher carbon yield than heterotrophs by co-utilizing organic carbons and CO2. However, the quantitative information of such `photo-fermentation' process is still limited. Decoding the carbon metabolism of cyanobacteria during the photo-fermentation process can reveal the functional pathways, carbon distribution, and the energy requirement, all …

Numerical Simulation And Optimization Of Carbon Dioxide Utilization For Enhanced Oil Recovery From Depleted Reservoirs, Razi Safi

McKelvey School of Engineering Theses & Dissertations

Due to concerns about rising CO₂ emissions from fossil fuel power plants, there has been a strong emphasis on the development of a safe and economical method for Carbon Capture Utilization and Storage (CCUS). One area of current interest in CO₂ utilization is the Enhanced Oil Recovery (EOR) from depleted reservoirs. In an Enhanced Oil Recovery system, a depleted or depleting oil reservoir is re-energized by injecting high-pressure CO₂ to increase the recovery factor of the oil from the reservoir. An additional benefit beyond oil recovery is that the reservoir could also serve as a long-term storage …

Development Of Nanofiber Scaffolds With Controllable Structure And Mineral Content For Tendon-To-Bone Repair, Justin Herrold Lipner

McKelvey School of Engineering Theses & Dissertations

Rotator cuff tears are common and lead to significant pain and disability. Effective repair of torn rotator cuff tendons requires healing of tendon to bone. Unfortunately, healing does not reproduce the structural and compositional features of the natural tendon-to-bone bone attachment that are necessary for effective load transfer, and surgical repairs often rupture.

Recent efforts for improving tendon-to-bone healing have focused on tissue engineering approaches. Scaffolds, cells, and/or growth factors are implanted at the repair site to guide the healing process and improve outcomes. To that end, a polymer-mineral tissue engineered scaffold was developed for this thesis which mimics two …

Human Ipsilateral Motor Physiology And Neuroprosthetic Applications In Chronic Stroke, David Thomas Bundy

McKelvey School of Engineering Theses & Dissertations

Improving the recovery of lost motor function in hemiplegic chronic stroke survivors is a critical need to improve the lives of these patients. Over the last several decades, neuroprosthetic systems have emerged as novel tools with the potential to restore function in a variety of patient populations. While traditional neuroprosthetics have focused on using neural activity contralateral to a moving limb for device control, an alternative control signal may be necessary to develop brain-computer interface (BCI) systems in stroke survivors that suffer damage to the cortical hemisphere contralateral to the affected limb. While movement-related neural activity also occurs in the …

Polarization Sensor Design For Biomedical Applications, Timothy York

McKelvey School of Engineering Theses & Dissertations

Advances in fabrication technology have enabled the development of compact, rigid polarization image sensors by integrating pixelated polarization filters with standard image sensing arrays. These compact sensors have the capability for allowing new applications across a variety of disciplines, however their design and use may be influenced by many factors. The underlying image sensor, the pixelated polarization filters, and the incident lighting conditions all directly impact how the sensor performs.

In this research endeavor, I illustrate how a complete understanding of these factors can lead to both new technologies and applications in polarization sensing. To investigate the performance of the …

Application-Specific Memory Subsystems, Joseph George Wingbermuehle

McKelvey School of Engineering Theses & Dissertations

The disparity in performance between processors and main memories has

led computer architects to incorporate large cache hierarchies in

modern computers. These cache hierarchies are designed to be

general-purpose in that they strive to provide the best possible

performance across a wide range of applications. However, such a memory

subsystem does not necessarily provide the best possible performance for

a particular application.

Although general-purpose memory subsystems are desirable when the

work-load is unknown and the memory subsystem must remain fixed,

when this is not the case a custom memory subsystem may be beneficial.

For example, in an application-specific integrated circuit …

Probing Mechanical Forces In Flagella By Manipulation Of Media Viscosity And Axonemal Structure, Kate Wilson

McKelvey School of Engineering Theses & Dissertations

Cilia and flagella are subcellular organelles used to generate fluid flow or propel the cell. These long cylindrical structures are composed of cytoskeletal elements activated by the unidirectional motor protein dynein. Cilia and flagella are crucial to a number of physiological functions, yet the specific mechanisms of dynein activation and coordination remain unclear. This work investigates the response of the flagellum of Chlamydomonas reinhardtii to increased mechanical loading achieved by variation of media viscosity, and to structural changes achieved by genetic manipulation. Effects of these perturbations are quantified using high spatiotemporal resolution recordings; the results demonstrate mutation-specific changes to the …

Utilizing Magnetic Tunnel Junction Devices In Digital Systems, Michael James Hall

McKelvey School of Engineering Theses & Dissertations

The research described in this dissertation is motivated by the desire to effectively utilize magnetic tunnel junctions (MTJs) in digital systems. We explore two aspects of this: (1) a read circuit useful for global clocking and magnetologic, and (2) hardware virtualization that utilizes the deeply-pipelined nature of magnetologic.

In the first aspect, a read circuit is used to sense the state of an MTJ (low or high resistance) and produce a logic output that represents this state. With global clocking, an external magnetic field combined with on-chip MTJs is used as an alternative mechanism for distributing the clock signal across …