Engineering Commons^™

Noise And Gain Characterization Of Interband Cascade Infrared Photodetectors, Eli A. Garduño

Electrical and Computer Engineering ETDs

Infrared (IR) detectors are an enabling technology for a broad and growing list of applications including gas detection, night vision, and space-based missile warning. There are ongoing efforts in IR detector research to explore the potential of new material systems and energy band structures in addition to continuously improving their sensitivity through increasing their quantum efficiency and lowering their dark current and noise. This dissertation examines an emerging class of IR detectors known as Interband Cascade Infrared Photodetectors (ICIPs).

ICIPs contain multiple regions to facilitate the collection of photogenerated electrons and to limit unwanted dark current. Theory regarding their performance …

Effect Of Strong Electrolyte Containing Gelling Aids On The Sol-Gel Transition Temperature Of Hypromellose 2910, Elnaz Sadeghi

Biomedical Engineering ETDs

Hypromellose, or hydroxypropyl methylcellulose (HPMC) - has been widely used for biomedical and pharmaceutical applications due to its advantages, including that it is modifiable in terms of viscosity, and it has the ability to form thermally reversible hydrogels. The thermal gelation temperature (T_Gel) of a given HPMC solution strongly depends on its characteristic grade and the solution concentration. Applying certain additives can modify the T_Gel even further; depending on their nature and concentration. With the addition of said additives, a lower or higher T_Gel can be obtained. For example, the addition of sodium chloride (NaCl) reduces …

Sub-Nanometer Coupling Distance Control And Plasmon Enhanced Carrier Generation And Dynamics In Iii-V Semiconductor Heterostructures, Sharmin Haq

Optical Science and Engineering ETDs

Plasmonic modes in metal nanostructures enable light confinement at subwavelength scales. This field confinement is important for exploring the potential of nanotechnology in miniaturization of optics as well as for the advancement of optoelectronic devices, such as photodetectors, photovoltaics, and light-emitting diodes. Plasmon resonances are also ideal for developing ultrasensitive biosensors, and for enhancing surface photochemistry and photocatalysis. The increasing number of plasmon applications requires fundamental understanding of the plasmon coupled system which has not yet been completely understood. Controlling and engineering the plasmon response at the nanoscale will open still more applications in material science, communications, biochemistry and medicine. …

Elevated Temperature Progressive Damage And Failure Of Duplex Stainless Steel, Darren P. Luke

Civil Engineering ETDs

Ductile failure of metals has been the focus of research efforts within academia and industry for many years since it is tremendously important for understanding the failure of structures under extreme loading conditions. However, limited research has been dedicated to elevated temperature ductile failure, which is critical for evaluating catastrophic events such as industrial, structural or shipping vessel fires. A detailed investigation was conducted on the structural response of Duplex Stainless Steel at elevated temperatures. The temperature dependence of elastic modulus, yield strength, ultimate strength, and ductility was measured up to 1000°C and a continuum damage plasticity model was developed. …

Chemically Modified Monolayer Surfaces Influence Valvular Interstitial Cell Attachment And Differentiation For Heart Valve Tissue Engineering, Matthew N. Rush

Nanoscience and Microsystems ETDs

As a cell mediated-process, valvular heart disease (VHD) results in significant morbidity and mortality world-wide. In the US alone, valvular heart disease VHD is estimated to affect 2.5% of the population with a disproportionate impact on an increasing elderly populous. It is well understood that the primary driver for valvular calcification is the differentiation of valvular interstitial cells (VICs) into an osteoblastic-like phenotype. However, the factors leading to the onset of osteoblastic-like VICs (obVICs) and resulting calcification are not fully understood and a more complete characterization of VIC differentiation and phenotypic change is required before treatment of valve disease or …

Stability Of A Spinning Triangle Tethered Spacecraft System In A Circular Orbit, Matthew James Heitstuman

Mechanical Engineering ETDs

Equations of motion are derived for a spinning triangle tethered spacecraft system and are used to analyze the stability of such systems. Floquet theory is applied to the linearized, periodic coefficient, equations of motion to analyze spin stability as a function of triangle geometry and the average spin rate of the satellite relative to the angular velocity of the spacecraft orbiting around a central body. The results of the Floquet analysis show that spin stability is achievable for many combinations of spacecraft geometry and spin rate. Spacecraft engineers or operators for a triangle-shaped tethered spacecraft can use this information for …

An Engineered Fit-For-Purpose Polymer Nanocomposite Seal Repair Material For Wellbores, Moneeb Genedy

Civil Engineering ETDs

Seal integrity of wellbores has become of significant interest due to repeated leakage and spill incidents occurring worldwide that jeopardize both human health and the environment in addition to causing significant economic burden. This is attributed to the fact that wellbores intersecting geographical formations contain potential leakage pathways. The cement-steel and cement-rock formation interfaces are recognized as two critical leakage pathways.

A seal repair material that has good bond strength with both steel and rock formations in addition to the ability to completely fill thin microcracks is needed to restore the seal integrity of wellbores. In this research, engineered polymer …

Development Of The University Of New Mexico Spectrometer For High-Resolution Fission Product Yield Data, Richard Emery Blakeley

Nuclear Engineering ETDs

Well-defined fission product yield data has been of increasing interest in various applications within the nuclear industry. With this need in mind, a fission fragment mass spectroscopy system was designed and developed at the University of New Mexico in collaboration with the Los Alamos National Laboratories with a stated goal of attaining a mass resolution of ≤ 1 % (FWHM/centroid) for light fragments and near 1 % for heavy fragments. The mass spectrometer utilized in this work consists of a transmission time-of-flight detection system to measure fission product velocity and an axial ionization chamber to measure the fission product energy, …

Integration Of A Commercial Smart Thermostat To The Aggregated Load Control Simulation Framework, Jee Won Choi

Mechanical Engineering ETDs

As part of an effort to achieve a better balance between the power demand and supply, load (demand) control simulation framework is previously developed. In the framework, HVAC load is used as a control resource, driven by the thermostat logic modeled within the framework. However, it has not been proved, whether a com- mercial thermostat is able to perform modeled thermostat’s features. Therefore, it is desired to integrate a commercial thermostat to the framework, to verify its capabil- ity of participating and performing the Demand Response (DR) scheme developed. A ‘Nest Learning Thermostat’ is selected as a commercial thermostat. Nest …

The Nature Of Ephemeral Secrets In Reverse Engineering Tasks, Antonio Miguel Espinoza

Computer Science ETDs

Reverse engineering is typically carried out on static binary objects, such as files or compiled programs. Often the goal of reverse engineering is to extract a secret that is ephemeral and only exists while the system is running. Automation and dynamic analysis enable reverse engineers to extract ephemeral secrets from dynamic systems, obviating the need for analyzing static artifacts such as executable binaries.

I support this thesis through four automated reverse engineering efforts: (1) named entity extraction to track Chinese Internet censorship based on keywords; (2) dynamic information flow tracking to locate secret keys in memory for a live program; …

Transverse Anderson Localization In Optical Fibers: High-Quality Wave Transmission And Novel Lasing Applications, Behnam Abaie

Optical Science and Engineering ETDs

In this dissertation, transverse Anderson localization (TAL) of light mediated by disordered optical fibers is exploited for high-quality optical wave transmission and novel random lasing applications. En route, we first establish a powerful numerical platform for detailed investigation of TAL optical fibers (TALOF). Our approach is based on a modal perspective as opposed to beam propagation method (BPM) which was primarily used in the previous studies of TAL in disordered optical fibers. The versatile numerical tools developed in our simulations result in a potent methodology for simulation of TALOFs; the result is a fast and effective algorithm which can be …

Investigating The Electrodeposition Of Plutonium And Curium For Safeguarding The Electrorefiner, Chantell L. Murphy

Nuclear Engineering ETDs

This research investigated the electrochemical deposition behavior of plutonium (Pu) and curium (Cm) for safeguarding the electrorefiner (ER) in a pyroprocessing facility. The main goal of this investigation was to evaluate the feasibility of using a safeguards concept called the neutron balance method to account for Pu in the ER. The neutron balance method relies on a known Pu/Cm ratio and measures neutrons from Cm-244 coming into and leaving a unit operation to track Pu. The application of the neutron balance approach for pyroprocessing facilities requires that Pu and Cm remain together in all extraction, product recovery, and waste streams. …

Frequency Domain Decomposition Of Digital Video Containing Multiple Moving Objects, Victor M. Stone

Electrical and Computer Engineering ETDs

Motion estimation has been dominated by time domain methods such as block matching and optical flow. However, these methods have problems with multiple moving objects in the video scene, moving backgrounds, noise, and fractional pixel/frame motion. This dissertation proposes a frequency domain method (FDM) that solves these problems. The methodology introduced here addresses multiple moving objects, with or without a moving background, 3-D frequency domain decomposition of digital video as the sum of locally translational (or, in the case of background, a globally translational motion), with high noise rejection. Additionally, via a version of the chirp-Z, fractional pixel/frame motion detection …

Scalable Stochastic Reachability: Theory, Computation, And Control, Abraham Puthuvana Vinod

Electrical and Computer Engineering ETDs

Guaranteeing safety and performance are crucial components in any control system, and particularly relevant in light of growing interest in reliable autonomy. In safety-critical applications like biomedical devices, spacecraft applications, and self-driving cars, the cost of failure can be severe. Verification provides these guarantees by characterizing the ``good'' initial states or configurations from which a state can be driven to remain within a collection of pre-specified safe sets, while respecting the system dynamics, bounds on control authority, and additive uncertainties. We also wish to design controllers to achieve this objective. This dissertation proposes novel theory and scalable algorithms for tractable …

Scalable, Biofunctional, Ultra-Stable Nano- Bio- Composite Materials Containing Living Cells, Patrick E. Johnson, C. Jeffrey Brinker, Graham Timmins, Jacob Agola, Jason Harper

Nanoscience and Microsystems ETDs

Three-dimensional encapsulation of cells within nanostructured silica gels or matrices enables applications as diverse as biosensors, microbial fuel cells, artificial organs, and vaccines. It also allows study of individual cell behaviors. Recent progress has improved the performance and flexibility of cellular encapsulation, yet there remains a need for robust scalable processes for large format production of cell-encapsulating materials. Here, we detail two novel techniques, that enable the large-scale production of functional Nano-Bio-Composites (NBCs) containing living cells within ordered 3-D lipid/silica nanostructures: 1) thick-casting and 2) spray drying. Furthermore, we detail a third technique for material scaling in which aqueous, silicate-based …

Criticality Assessments For Improving Algorithmic Robustness, Thomas B. Jones

Computer Science ETDs

Though computational models typically assume all program steps execute flawlessly, that does not imply all steps are equally important if a failure should occur. In the "Constrained Reliability Allocation" problem, sufficient resources are guaranteed for operations that prompt eventual program termination on failure, but those operations that only cause output errors are given a limited budget of some vital resource, insufficient to ensure correct operation for each of them.

In this dissertation, I present a novel representation of failures based on a combination of their timing and location combined with criticality assessments---a method used to predict the behavior of systems …

Exposure Assessment Of Citizens To Traffic Related Air Pollutants In A Long-Range Transportation Plan, Amir Poorfakhraei

Civil Engineering ETDs

A large body of evidence links fine particulate matter (PM_2.5) exposure with a wide range of negative health outcomes. Research finds that about 30% of individuals’ exposure to particulate matter in urban areas come from mobiles sources. Evaluating regional transportation plans and estimating how they impact air quality and exposure to PM_2.5 in the future is thus of major concern.

There are two major concerns about the current practice of evaluating regional transportation plans also known as long-range transportation plans (LRTPs). First, how LRTPs affect future air quality are at best evaluated by estimating the change in …

Investigation Of The Formation Of Γꞌꞌ Precipitates Under Ion Irradiation And Elevated Temperature Environments, James R. Pike

Nuclear Engineering ETDs

During a preventative maintenance at the Los Alamos Neutron Science Center (LANSCE) Isotope Production Facility (IPF), a beam window made of solution annealed Alloy 718 was replaced and the old beam window was analyzed. The old beam window underwent mechanical testing and microstructure analysis. During the microstructure analysis, the formation of γꞌꞌ precipitates was observed in Transmission Electron Microscopy (TEM) electron diffraction pattern. The formation of γꞌꞌ precipitates was not expected since they are not stable under irradiation. Furthermore, the formation of γꞌꞌ precipitates was observed only at a temperature of 33ºC, and a dose of 0.7 displacement per atom …

Vertical Transport Study Of Iii-V Type-Ii Superlattices, Zahra Taghipour

Optical Science and Engineering ETDs

Type-II strained layer superlattice (T2SL) semiconductors hold great promise for mid- and long-wavelength infrared photodetectors. While T2SL-based materials have advanced significantly in the last three decades, an outstanding challenge to improve the T2SLs is to understand the carrier transport and its limitations, in particular along the superlattice growth layers.

In this dissertation, an overview of the current state-of-the-art InAs/GaSb T2SLs is presented. Fundamental semiconductor device equations and transport properties, including miniband conduction and the drift-diffusion parameters, are reviewed, and the fundamental limiting factors in carrier's transport are discussed. Furthermore, the standard method of electron-beam-induced current technique to measuring these parameters …

Frameworks To Investigate Robustness And Disease Characterization/Prediction Utility Of Time-Varying Functional Connectivity State Profiles Of The Human Brain At Rest, Anees Abrol

Electrical and Computer Engineering ETDs

Neuroimaging technologies aim at delineating the highly complex structural and functional organization of the human brain. In recent years, several unimodal as well as multimodal analyses of structural MRI (sMRI) and functional MRI (fMRI) neuroimaging modalities, leveraging advanced signal processing and machine learning based feature extraction algorithms, have opened new avenues in diagnosis of complex brain syndromes and neurocognitive disorders. Generically regarding these neuroimaging modalities as filtered, complimentary insights of brain’s anatomical and functional organization, multimodal data fusion efforts could enable more comprehensive mapping of brain structure and function.

Large scale functional organization of the brain is often studied by …

Rate-Determining Step And Active Sites Probing For Platinum-Group-Metal Free Cathode Catalyst In Fuel Cell, Yechuan Chen

Chemical and Biological Engineering ETDs

With the increasing demand on renewable energy, the fuel cell has attracted more and more interests because of its large power density and controllable size. However, the insufficiency of element abundance and unstable expensive price of conventional platinum-based electrocatalysts used in anode and cathode makes it essential to find their substitutes. As one of the most promising candidates to be used in cathode for oxygen reduction reaction (ORR), iron-nitrogen-carbon (Fe-N-C) catalysts have been widely investigated and get commercialized recently, but still lacks comprehensive understanding on the kinetic mechanism.

This dissertation has been divided into three parts with a discussion on …

Acoustofluidics And Soft Materials Interfaces For Biomedical Applications, Frank A. Fencl

Biomedical Engineering ETDs

This dissertation describes fabrication of devices and other tools for biomedical applications through the integration of acoustofluidic systems with bio separation assays, instrumentation components, and soft materials interfaces. For example, we engineer a new class of transparent acoustic flow chambers ideal for optical interrogation. We demonstrate efficacy of these devices by enhancing the signal for high throughput acoustic flow cytometry, capable of robust particle focusing across multiple parallel flowing streams. We also investigate an automated sampling system to determine the parameters of transient particle stream focusing in between sample boluses and air bubbles to model a high throughput, multi-sampling acoustic …

Carrier Lifetime Vs. Proton Radiation In Prototype Iii-V And Ii-Vi Space-Based Infrared Detectors, Geoffrey D. Jenkins

Electrical and Computer Engineering ETDs

Researchers have spent over 50 years improving the performance of HgCdTe infrared (IR) detectors and it is currently the dominant technology in the field; however, further improvement may be limited due to devices reaching the intrinsic limits of their constituent materials. To further improve the state-of-the-art in space-based IR detection, alternative material systems are being considered. The focus of this work is testing the space-environment viability of innovative device structures, namely unipolar barriers with Type-II superlattice (T2SL) absorbers, made from the 6.1 Å family of III-V elements which are theoretically superior performers while being less costly.

Sensitive IR photo-detection using …

Cloudsat: Iot Approach To Small Satellite Ground Infrastructure, Brian Zufelt

Electrical and Computer Engineering ETDs

Over the last decade, the cost of space access has dramatically decreased with the creation of the CubeSat standard. The CubeSat standard defines the structural requirements for an on-orbit deployer and satellite to be placed into orbit. The average cost of creating a space mission with the CubeSat standard can range from $200 thousand to over $3 million. This lower cost has allowed many Universities, and small businesses to create their own space programs. However, a significant portion of the investment for any new space asset is the development of the ground system to communicate with the satellite. These costs …

Carrier Dynamics In High-Speed Iii-Nitride Light-Emitting Diodes For Visible-Light Communication, Arman Rashidi

Optical Science and Engineering ETDs

III-nitride light-emitting diodes (LEDs) are now ubiquitous in solid-state lighting (SSL) systems. Despite the significant advancement of III-nitride LEDs, the origins of fundamental challenges such as efficiency droop, thermal droop, and green gap are not completely understood. In addition, emerging applications such as micro-pixel LED displays and visible-light communication (VLC) require efficient LEDs capable of high-speed modulation. Studies of carrier dynamics are essential to better understand the fundamental efficiency challenges and enable the design of high-efficiency, high-speed LEDs. Among approaches to characterize the carrier dynamics in LEDs, electrically injected methods are preferred over optically pumped methods to capture the carrier …

Investigation Of Acetaminophen And Caffeine Removal Using Manganese Oxides And Granular Activated Carbon In Column Experiments, Rachael E. Miera

Civil Engineering ETDs

This study was conducted to investigate the application of manganese dioxide (MnO_x(s)) and granular activated carbon (GAC) media for the removal of the acetaminophen and caffeine. Treatment of emerging micropollutants has become a concern due to their effects on environmental health. Manganese oxides can be a viable alternative for water treatment due to their abundance in the environment. Laboratory scale flow through column experiments were performed using different combinations of commercial MnO_x(s) and GAC to assess the removal of caffeine and acetaminophen, and the release of Mn due to the reductive dissolution of MnO_x(s). Results …

Engineering Viscoelastic Behavior Of Carbon Fiber Reinforced Polymer Composites With Nanoparticles For Controlling Deployment Of Aerospace Structures, Mark Scherbarth

Mechanical Engineering ETDs

The United States Air Force is focused on reducing mass and power consumption of spacecraft to increase their capabilities for space missions. Low mass and power consumption can be achieved by using composites with low density and high stiffness and utilizing few satellite components. One way to achieve reduced mass is by eliminating attendant deployment mechanisms consuming valuable power and mass allocations on spacecraft with deployable structures. Secondary systems are typically used to assist deployable space structures to ensure 100% success. A passively deployed space structure would be of great value to the Department of Defense and the commercial marketplace. …

A Novel Indoor Positioning System For Firefighters In Unprepared Scenarios, Vamsi Karthik Vadlamani

Electrical and Computer Engineering ETDs

Situational awareness and indoor positioning of firefighters are types of information of paramount importance to the success of search and rescue operations. GPS units are undependable for use in Indoor Positioning Systems due to their associated mar- gins of error in position and their reliance on satellite communication that can be interrupted inside large structures. There are few other techniques like dead reck- oning, Wifi and bluetooth based triangulation, Structure from Motion (SFM) based scene reconstruction for Indoor positioning system. However due to high temper- atures, the rapidly changing environment of fires, and low parallax in the thermal images, the …

A Narrow-Wall Complementary-Split-Ring Slotted Waveguide Antenna For High-Power-Microwave Applications, Xuyuan Pan

Electrical and Computer Engineering ETDs

A narrow-band, rugged, complementary-split-ring (CSR) slotted waveguide antenna (SWA) with significant size reduction is presented. The antenna is to be vertically front mounted on a land vehicle, with a horizontally polarized fan-beam radiation pattern. The radiation characteristics of a CSR slot in the narrow-wall of a rectangular waveguide are studied for the first time in this work. Both simulation and experimental results show that the complementary-split-ring slot radiates a linearly polarized wave with a total efficiency and gain close to those of conventional longitudinal slots, while the proposed CSR slots have a maximal outer diameter of 0.23λ₀, much …

Oxygen And Silver-Oxygen Defects In Ge2se3 Electrochemical Metallization Bridge Memristors, Jau-Tzuoo Chen

Electrical and Computer Engineering ETDs

We present density functional theory (DFT) calculations of oxygen and silver defects in a crystalline model of amorphous Ge₂Se₃. We studied defects arising from atomic oxygen and dioxygen, as well as interstitial silver and silver displacing germanium, following Campbell's conjecture on the mechanism of dendrite formation. For oxygen defect concentrations below 2%, we show that O₂ dissociates in Ge₂Se₃, oxygen atoms are immobile, and oxygen atoms do not cluster. Within this model, the most preferred oxygen defect in intrinsic Ge₂Se₃ is Ge-O-Ge bridge. We conclude that oxygen defects …