Engineering Commons^™

A Biomechanical Comparison Of A Low-Profile Mesh Plate Contrasted With Tension Band Wiring Treatment Of Olecranon Fractures And Osteotomies, Jasmin Regalado

Mechanical Engineering ETDs

Olecranon fractures are common upper extremity injuries caused by direct trauma to the elbow. Open reduction and internal fixation is the current standard for olecranon fractures that exceed a 2 mm fragment displacement. The tension band wire (TBW) technique is the current standard of care for treating olecranon fractures due to its positive clinical results. However, the complication rate due to prominent hardware is reported to be upwards of 50\%. This research aims to biomechanically test and compare the stiffness and fracture gap of the traditional TBW technique to a low-profile titanium mesh plate (TMP) for chevron-type fractures and osteotomies …

Radiation Effects In Metal Oxides And Carbides, Benjamin Jackson Cowen

Nuclear Engineering ETDs

MD simulations of SiO₂, TiO₂, Cr₂O₃, Al₂O₃, MgO, and SiC, are performed to: (a) calculate TDE probability distributions and dependence on crystallographic direction, and (b) determine the number and types of defects formed with low- and high-energy PKAs and projectiles. In addition, a qualitative comparison of the MD simulation results of radiation damage in TiO₂, MgO, and crystalline and amorphous SiC thin films are compared with those of in situ TEM ion beam irradiation experiments at the Sandia National Laboratories’ I³TEM facility.

The TDE …

Modeling And Simulation Of Damage In The Brazilian Indirect Tension Test Using The Finite-Discrete Element Method, Jeremiah C. Leyba

Civil Engineering ETDs

The Brazilian indirect tension test is used to investigate possible correlations between progressive damage and associated permeability changes. The test offers ease of replicability with a damage behavior known to lead to fracture openings as a tool for interpreting the indirect tensile strength of concrete and rocks. This behavior can lend insight into the nature of tensile damage and fracture progression in association with changes in permeability. The nature of these brittle materials is known to exhibit rapid failures in the Brazilian indirect tension test and require a method to retard the progression of damage for the possibility of acquiring …

Characterization Of Gallium Nitride Photoconductive Semiconductor Switches In The Nonlinear Regime, Joseph D. Teague

Electrical and Computer Engineering ETDs

The energy demands of an increasingly electrified world have caused a renewed interest in once dormant fields of research. Photoconductive Semiconductor switches (PCSS) are one of these fields. They theoretically offer high voltage, high current switching in sub cm³ packaging, without the shot to shot variation and bulk of current high-power DC switches such as spark gaps. PCSS are capable of power densities of 10⁹-10¹⁰ W/cm³, with electric fields ranging from 10⁵-10⁶ V/cm and current densities from 10⁴-10⁶ A/cm² [1].

Most PCSS make a trade-off between voltage, …

Understanding Asphalt Concrete Aging Using Nanoindentation, Hasan M. Faisal

Civil Engineering ETDs

Asphalt concrete (AC) is created by mixing liquid asphalt binder with solid aggregates. When asphalt binder is mixed with aggregates, it creates a thin film (about 7-16 microns thick) around the aggregate surface. Fine aggregate (smaller than 0.075 mm size) get entrapped within the binder film or mixed with the binder, and create a phase called mastic. Both asphalt film and mastic play significant roles in aging of asphalt pavement. To this day, tests were performed mainly on the bulk liquid asphalt, but not on the film or mastic. In this study, for the first time, nanoindentation tests were done …

Decision-Making Framework For The Selection Of Sustainable Alternatives For Energy-Retrofits, Amirhosein Jafari

Civil Engineering ETDs

Buildings are major consumers of energy worldwide. On the other hand, over 60% of the US housing inventory is over 30 years old and a large number of these homes are energy inefficient. Therefore, it is essential to target the existing building stock for energy efficient interventions as a key to substantially reduce the adverse impacts of buildings on the environment and economy.

Building energy retrofitting has emerged as a primary strategy for reducing energy use and carbon emissions in existing buildings. An energy retrofit can be defined as a physical or operational change in a building, its energy-consuming equipment, …

Tunneling In Si Mos Nanostructures, Amir Shirkhorshidian

Electrical and Computer Engineering ETDs

In this dissertation, split-gate tunnel barriers in enhancement-mode silicon metal- oxide-semiconductor (MOS) device structures are characterized electrically at liquid helium temperatures (T = 4.2 K) using transport spectroscopy. Tunnel barriers with different gate geometries and barriers implanted with a small number of antimony donor atoms are characterized. Low disorder MOS tunnel barriers are demonstrated and compared to the implanted cases. The ”clean” MOS tunnel barriers are an important proof of principle that disorder free tunnel barriers can be achieved in MOS. The implanted cases provide an important reference for the effects of donors and shallow traps on a MOS tunnel …

Hand Movement Detection In Collaborative Learning Environment Videos, Callie J. Darsey

Electrical and Computer Engineering ETDs

Human activity detection in digital videos is currently attracting significant research interest. This problem is especially challenging for video datasets that have a lot of human activity, illumination noise, and structural noise. The video dataset associated with the Advancing Out of School Learning in Mathematics and Engineering (AOLME) project has these challenges. ALOME videos have been used in the study of human activities “in the wild”.

This thesis explores detection of hand movement using color and optical flow. Exploratory analysis considered the problem component wise on components created from thresholds applied to motion and color. The proposed approach uses patch …

An Investigation Into Remote Sensing Techniques For Describing Hydraulic Roughness, Smriti Chaulagain

Civil Engineering ETDs

Riparian vegetation, an indicator of healthy river system, increases the hydraulic roughness and reduces the conveyance capacity of a channel. Vegetation provides dominant drag force influencing the velocity distribution, turbulence intensity and water depth. Thus, the study of hydraulic roughness due to vegetation is essential to determine the characteristics of flow. Traditionally, a constant Manning’s roughness value is assigned based on land cover maps and that does not adequately account for vegetation. The roughness due to vegetation are determined on the basis of its parameters like height, density, LAI and flexibility. Remote sensing data (LiDAR, aerial photos or satellite images) …

Capacitive Pcb Security For Active Tamper And Alteration Detection, Casey Petersen

Electrical and Computer Engineering ETDs

The purpose of the research presented is to establish the viability of using capacitive based sensors for the purpose of hardware security at the Printed Circuit Board (PCB) level. Capacitive sensors are traditionally used to sense changes to the areas surrounding the sensing pads in applications such as sensing proximity, position, humidity, fluid levels and much more.

The specific sensor used for this research is an inductor-capacitor (LC) based Capacitance-to-Digital Converter. This configuration is virtually immune to EM noise because it is a tank circuit and therefore filters out the noise which, in the past, caused reliability issues with these …

Characterizing Patterns In E. Coli Levels In Rio Grande River Water And Riverbed Sediments Near Albuquerque, Nm, James Fluke

Civil Engineering ETDs

In this work I examined how Fecal indicator Bacteria (FIB) behave in a large environmental system (Rio Grande near Albuquerque, ~60 km distance). I addressed the questions: How do FIB levels in river water and riverbed sediments of this reach change with distance along the river and throughout one year?

I conducted year-round river water and sediment sampling for concentration of E. coli bacteria, a persistent contaminant in the area. I found that over the year, E. coli loading in river water increased along the 60 km reach and E. coli in the sediments mainly increased near the Albuquerque urban …

Pulse Sharpening Circuit For Explosive Emission Cathode Driver, Nicholas D. Kallas

Electrical and Computer Engineering ETDs

Explosive field emission cathodes (EEC), used for the generation of relativistic electron beams, require short rise-time high-voltage pulses in order to minimize the extraction of off-energy electrons. To this end, a rise-time sharpening circuit has been developed at the Los Alamos National Laboratory (LANL). The circuit consists of a 7 nF water-filled peaking capacitor with an integrated self-breakdown switch designed to operate up to -300 kV. This unit is intended to reduce the rise-time of a 4-stage Type-E PFN Marx Generator that will be used to study operational characteristics of velvet cathodes. Simulations of the peaking circuit show a reduction …

Data-Driven Uncertainty Quantification Interpretation With High Density Regions, Matthew Gregor Peterson

Computer Science ETDs

In a time when data is being constantly generated by phones, vehicles, sensor net- works, social media, etc. detecting anomalies with in the data can be very crucial. In cases where we know little prior knowledge about the data, it becomes difficult to extract uncertainty about our results. In this thesis, we will propose a framework in which we can extract uncertainty distributions from data-driven modeling prob- lems. We will show some concrete examples of how to apply framework and provide some insight into what the uncertainty distributions are telling us using High Density Regions (HDRs).

Metal Reactivity In Laboratory Burned Wood From A Watershed Affected By Wildfires, Asifur Rahman

Civil Engineering ETDs

Massive amounts of wood ash are deposited into nearby streams as a result of runoff from storm events after increasing frequency of wildfire events that negatively affect water quality. Ash and debris from burned vegetation can alter the pH, turbidity and dissolved oxygen (DO) in water and can release heavy metals, organic matter, and nutrients. We investigated interfacial processes affecting metal mobility in wood ash burned under laboratory-controlled conditions using aqueous chemistry, microscopy and spectroscopy analyses. Wood was collected from the Valles Caldera National Preserve in New Mexico which has experienced two wildfires since 2011 that have caused devastating effects. …

Selected Applications Of Silicon Nanopillar Arrays., Behnam Kheyraddini Mousavi

Electrical and Computer Engineering ETDs

Interaction of optical waves with nanostructures made of various material systems has been the subject of intensive research for many years. These researches have been mainly driven by the need to make smaller optical devices and exploiting the functionalities offered by light-matter interaction in nanoscale. Majority of the nanostructures are fabricated using electron beam (e-beam) lithography that is slow and expensive. As such alternative methods have been developed to enable nanoscale fabrication faster and less expensive. Among these interferometric lithography (IL) is a relatively simple method for quick fabrication of nanostructures. As IL method generates periodic patterns, exploring the potential …

Intelligent Computational Transportation, Yuming Zhang

Electrical and Computer Engineering ETDs

Transportation is commonplace around our world. Numerous researchers dedicate great efforts to vast transportation research topics. The purpose of this dissertation is to investigate and address a couple of transportation problems with respect to geographic discretization, pavement surface automatic examination, and traffic ow simulation, using advanced computational technologies. Many applications require a discretized 2D geographic map such that local information can be accessed efficiently. For example, map matching, which aligns a sequence of observed positions to a real-world road network, needs to find all the nearby road segments to the individual positions. To this end, the map is discretized by …

High-Performance Testbed For Vision-Aided Autonomous Navigation For Quadrotor Uavs In Cluttered Environments, Shakeeb Ahmad

Electrical and Computer Engineering ETDs

This thesis presents the development of an aerial robotic testbed based on Robot Operating System (ROS). The purpose of this high-performance testbed is to develop a system capable of performing robust navigation tasks using vision tools such as a stereo camera. While ensuring the computation of robot odometery, the system is also capable of sensing the environment using the same stereo camera. Hence, all the navigation tasks are performed using a stereo camera and an inertial measurement unit (IMU) as the main sensor suite. ROS is used as a framework for software integration due to its capabilities to provide efficient …

Synchronization In An Externally Driven Mechanical Oscillators Experiment, Sumit Chhabria

Electrical and Computer Engineering ETDs

Our experimental system studies the effects of externally controlled oscillation on directly and indirectly driven system of metronomes. This is analogous to many practical systems such as pacemaker effect on heart cells, the external light effect on the suprachiasmatic nucleus in the brain. Here the pacemaker can be compared to an external driving force to the system where the heart cells are our oscillating system. Also, in the suprachiasmatic nucleus cell system, the external input is external light which synchronizes the cell. We explore the synchronization of directly and indirectly driven metronomes due to externally provided forcing.

We designed an …

Bioengineering Of An In Vitro Microphysiological Human Alveolar Model, Ayesha Arefin

Nanoscience and Microsystems ETDs

Drugs tested on animal models do not always produce the same results in humans; a reliable in vitro lung model can bridge the divide between the two. Because the alveolus is a target for several drugs, an alveolar model can be a platform for both designing drugs and studying lung diseases. A model should allow for gas exchange, growth of primary alveolar epithelial cells, extracellular matrix production, and have similar mechanical properties to alveoli, creating an environment conducive to normal metabolic activity and cellular responses. Existing artificial alveolar models that use polymeric membranes to sustain lung cells are limited by …

The Investigation Of Silica Removal In Reverse Osmosis Concentrate By Changing Design Parameters, John M. Stomp Iv

Civil Engineering ETDs

Silica at high concentrations can precipitate and polymerize, forming scales on heat exchangers, boilers and turbines in industrial equipment, and on the feed side of the semi-permeable membranes in Reverse Osmosis (RO). Silica scale can cause decreased efficiency, increased treatment costs and, in some cases, irreversible damage. The removal of silica scale is challenging because it requires the handling of dangerous and hazardous chemicals. Therefore, much research has gone into the removal of soluble silica. The purpose of this research was to compare the overall effectiveness of silica removal in RO concentrate water with freshly precipitated Mg(OH)₂ and Fe(OH) …

Novel Compact Narrow-Linewidth Mid-Infrared Lasers For Sensing Applications, Behsan Behzadi

Optical Science and Engineering ETDs

The mid-infrared (2-14 μm) spectral region contains the strong absorption lines of many important molecular species, which make this region crucial for several well-know applications such as spectroscopy, chemical and biochemical sensing, security, and industrial monitoring. To fully exploit this region through absorption spectroscopic techniques, compact and low-cost narrow-linewidth (NLW) mid-infrared (MIR) laser sources are of primary importance.

This thesis is focused on three novel compact NLW MIR lasers: demonstration and characterization of a new glass-based spherical microlaser, investigation of the performance of a novel fiber laser, and the design of a monolithic laser on a silicon chip. Starting with …

Developing Droplet Based 3d Cell Culture Methods To Enable Investigations Of The Chemical Tumor Microenvironment, Jacqueline A. De Lora

Biomedical Sciences ETDs

Adaptation of cancer cells to changes in the biochemical microenvironment in an expanding tumor mass is a crucial aspect of malignant progression, tumor metabolism, and drug efficacy. In vitro, it is challenging to mimic the evolution of biochemical gradients and the cellular heterogeneity that characterizes cancer tissues found in vivo. It is well accepted that more realistic and controllable in vitro 3D model systems are required to improve the overall cancer research paradigm and thus improve on the translation of results, but multidisciplinary approaches are needed for these advances. This work develops such approaches and demonstrates that new droplet-based cell-encapsulation …

Multirate Frequency Transformations: Wideband Am-Fm Demodulation With Applications To Signal Processing And Communications, Wenjing Liu

Electrical and Computer Engineering ETDs

The AM-FM (amplitude & frequency modulation) signal model finds numerous applications in image processing, communications, and speech processing. The traditional approaches towards demodulation of signals in this category are the analytic signal approach, frequency tracking, or the energy operator approach. These approaches however, assume that the amplitude and frequency components are slowly time-varying, e.g., narrowband and incur significant demodulation error in the wideband scenarios. In this thesis, we extend a two-stage approach towards wideband AM-FM demodulation that combines multirate frequency transformations (MFT) enacted through a combination of multirate systems with traditional demodulation techniques, e.g., the Teager-Kasiser energy operator demodulation (ESA) …

Compartmentalization Of Dna-Based Molecular Computing Elements Using Lipid Bilayers, Aurora Fabry-Wood

Biomedical Engineering ETDs

This dissertation will present a progression from the detection of double-stranded DNA using a combination of toehold-mediated strand displacement and DNAzyme reactions in dilute saline solutions, to the generation of separate compartments to allow standardization of DNA computing elements, by protecting from complementary strands. In well-mixed solutions complementary regions cause spurious interactions. Importantly, these compartments also provide protection from nucleases. Along the way we will also explore the use of silica microsphere supported lipid bilayers to run compartmentalized DNA reactions on a fluid surface and the design of a molecule capable of DNA-based transmembrane signal transduction.

Sonomechanical Enhanced Sparging Techniques For Advanced Reactor Applications, Floren V. Rubio

Nuclear Engineering ETDs

The fluoride salt cooled high temperature reactor (FHR) is a Generation IV advanced reactor design that has potential to produce efficient, low carbon, and safe energy. But, there are significant engineering challenges that need to be addressed before the deployment of this reactor. One of the key challenges is tritium release mitigation and sequestration. Because the FHR utilizes a eutectic LiF-BeF2 (flibe) salt as a coolant, the coolant is a significant source of tritium.

High-power ultrasonics have been used in many industrial process streams such as food processing, metal production, chemical production, and pharmaceutical manufacturing. Techniques and concepts from these …

On Improved Accuracy Chirp Parameter Estimation Using The Dfrft With Application To Sar-Based Vibrometry, Satish Mandal

Electrical and Computer Engineering ETDs

The Discrete Fractional Fourier Transform (DFRFT) has in recent years, become a useful tool for multicomponent chirp signal analysis. Chirp signals are transformed into spectral peaks in the chirp rate versus center frequency representation, whose coordinates are related to the underlying chirp parameters via a computed empirical peak to parameter mapping incorporated into the Santhanam-Peacock algorithm.

In this thesis, we attempt to quantify the accuracy of the DFRFT approach by first studying the discretization error sources that arise from the transitioning of the continuous FRFT to DFRFT. Then, we refine prior work by Ishwor Bhatta to develop analytical expressions for …

Automated Development Of Semantic Data Models Using Scientific Publications, Martha O. Perez-Arriaga

Computer Science ETDs

The traditional methods for analyzing information in digital documents have evolved with the ever-increasing volume of data. Some challenges in analyzing scientific publications include the lack of a unified vocabulary and a defined context, different standards and formats in presenting information, various types of data, and diverse areas of knowledge. These challenges hinder detecting, understanding, comparing, sharing, and querying information rapidly.

I design a dynamic conceptual data model with common elements in publications from any domain, such as context, metadata, and tables. To enhance the models, I use related definitions contained in ontologies and the Internet. Therefore, this dissertation generates …

Study Of Building Vibrations Caused By Machinery, Bipesh Shrestha

Civil Engineering ETDs

ABSTRACT

This thesis studies the vibration of structures caused by machinery. Machines exhibit unique vibrational characteristics. This thesis focuses on detection of these unique vibrational characteristics through the study of structural vibration caused by machines. The study extends from simple laboratory structures to a real existing building called the Ford Utility Building. The vibrational readings on the roof of the Ford Utility Building are studied to capture signals that can be attributed to machines running inside the building. This thesis supports the research in remote detection and identification of concealed machinery through SAR vibrometry.

A study of human perception of …

Achieving Public Health And Climate Change Goals: What Do We Need To Know About The Transportation System?, Mohammad Tayarani

Civil Engineering ETDs

The overall aim of this dissertation is evaluating what new knowledge can be gained about the environmental and public health outcomes of regional transportation planning strategies by implementing a suite of more spatially and temporally detailed transportation and air quality models. This new knowledge can be used to better understand the potential health effects of emissions exposure while also guiding the development of new transportation and land-use plans, and related policies that have the potential to achieve large reductions in pollution exposure and green house gas emissions at local and regional level.

Analysis Of Double-Wall And Twisted-Tube Heat Exchanger Concepts For Use In Fluoride Salt-Cooled High-Temperature Reactors, Bryan M. Wallace

Nuclear Engineering ETDs

Fluoride Salt-cooled High-temperature Reactors (FHRs) are an attractive fourth generation reactor concept. Like other fourth generation concept designs, FHRs offer characteristics such as a high-temperature low-pressure molten salt coolant allowing the reactor to be combined with a high-temperature high-efficiency power generation cycle such as an air-Brayton or supercritical carbon dioxide (SCO2). \par

Like most Gen IV reactor concepts, there are a few problems which need to be addressed with the design before it can be licensed. One particular design is the Mark 1 pebble bed FHR, a design put out by the University of California Berkeley. Two problems that need …