Engineering Commons^™

Dynamical Modeling Of Resistojet Style Thrusters For Fault Detection, And Fault Identification, Jonathan Leo Kerivan

Graduate College Dissertations and Theses

The work presented in this thesis investigates and validates the dynamic modeling, fault detection, and fault identification (FDI) for the resistojet thruster system, typically used in low magnitude thrust applications for smaller spacecraft. The resistojet thruster is an improvement upon the widely utilized cold gas thruster, featuring an incorporated heating section aimed at improving propellant efficiency. This additional heating section enhances the performance of the system by increasing the propellant’s thermal energy before its discharge through the nozzle, subsequently leading to a reduction in overall fuel consumption. To implement a model-based FDI technique tailored to the typical resistojet thruster system, …

Effective Drag Coefficient Prediction On Single-View 2d Images Of Snowflakes, Cameron Hudson

Graduate College Dissertations and Theses

The drag coefficient of snowflakes is an crucial particle descriptor that can quantify the relationships with the mass, shape, size, and fall speed of snowflake particles. Previous studies has relied on estimating and improving empirical correlations for the drag coefficient of particles, utilizing 3D images from the Multi-Angled Snowflake Camera Database (MASCDB) to estimate snowflake properties such as mass, geometry, shape classification, and rimming degree. However, predictions of the drag coefficient with single-view 2D images of snowflakes has proven to be a challenging problem, primarily due to the lack of data and time-consuming, expensive methods used to estimate snowflake shape …

Control Of Pneumatically Actuated Drones, Benjamin Scott Jackson

Graduate College Dissertations and Theses

Aerial autonomous vehicles have played a crucial role in assisting humans with safety-critical operations on Earth. Applications include natural disaster response, environment surveillance, and infrastructure inspection. As humans hope to return to the Moon, as per NASA's latest initiatives, autonomous vehicles could serve as a key component in keeping humans out of harm's way. However, many celestial objects lack an atmosphere, making propeller-powered drones inadequate. To address this problem, this thesis presents an optimal control methodology to demonstrate how systems actuated using cold gas thrusters may play the role of drones in space. In place of cold gas thrusters, this …

Surface Temperature Measurement Fidelity In High Enthalpy Plasma Test Facilities, Owen Plante

Graduate College Dissertations and Theses

The classification and study of thermal protection systems (TPS) relies heavily on the accurate measurement of surface temperature. The best way to measure surface temperature in ground test facilities is through optical pyrometery due to the non intrusive nature of this method. Optical pyrometric devices use the emission of a greybody curve to calculate temperatures. These devices are left susceptible to parasitic radiation coming from the plasma generated in ground test facilities. The parasitic radiation comes from the emission lines of the test plasma in the investigation region of the devices. The parasitic radiation from the plasma and short comings …

Investigation Of Silane Coating Treatments On Phynolic Impregnated Carbon Ablator For Mars And Future Planetary Exploration, Ian Ballou

Graduate College Dissertations and Theses

The atmospheric reentry of hypersonic vehicles causes extreme compression of the gas surrounding the hypersonic vehicle due to the extremely high velocities. These compressed gases create a high enthalpy plasma environment at the surface of the vehicle and transfer thermal energy through heating to the surface of the vehicle. An ablative heat shield is used as a thermal protective systems (TPS) for many hypersonic vehicles to mitigate the effects of excessive surface heating. An example of such a TPS material for NASA Mars and Titan missions is Phenolic Impregnated Carbon Ablator (PICA).On production vehicles, a commercially available NuSil coating is …

Silicon Carbide Fabric Catalysis Assessment In An Inductively Coupled Plasma Facility, Christopher Michael Nolan

Graduate College Dissertations and Theses

Flexible thermal protection systems (FTPS) are being considered as they allow for atmospheric reentry of larger payloads. Current rigid aeroshells struggle to achieve this as they are limited by the shroud of the rocket being used. One promising material candidate for these flexible heat shields is a Hi-Nicalon silicon carbide (SiC) fabric. By utilizing the UVM 30 kW Inductively Coupled Plasma Facility, an array of experiments were performed to explore the chemical response to plasma in a variety of atmospheric conditions. The main goal of this thesis is to better understand gas surface interactions, mainly through two-photon laser-induced fluorescence (TALIF) …

Surface Volatilization Investigation Of Graphite, Mitchell Stern

Graduate College Dissertations and Theses

The re-entry vehicle posseses enough kinetic energy that it becomes hypersonic while passing throughthe upper atmosphere. This kinetic energy is quickly transferred into thermal energy as the quiescent atmosphere turned hypersonics with reference to the vehicle suddenly stagnates. Furthermore, the high energy process of generating plasma also ablates the leading edge surfaces, causing reactions between the charged gasses and the solid material composing the thermal protection system (TPS) of the aircraft. These reactions can be exothermic an d pose an additional mode of heat transfer into the body of the aircraft. Learning more about the interactions within the boundary layer …

Tools To Measure Dispersion Descriptors From Polymer Nanocomposites, Kevin Dimas Zuniga Cuellar

Graduate College Dissertations and Theses

MaterialsMine is a new open-source data resource with the goal of supporting faster nanocomposite and metamaterials discovery and design. One goal of MaterialsMine is to provide tools that help researchers gain a better fundamental understanding of nanofiller behavior. While it is well known that the dispersion of nanofillers in nanocomposites critically controls properties, there is limited quantitative data. This thesis develops a methodology for quantitatively measuring the dispersion of polymer nanocomposites quickly and within the MaterialsMine data framework. The method processes transmission electron microscopy (TEM) images from MaterialsMine. TEM images are first pre-processed and transformed into binary images. Then the …

Atomic-Scale Analysis Of Solute Segregation Energy Into Grain Boundaries And Polycrystals, Tara Nenninger

Graduate College Dissertations and Theses

Solute segregation in grain boundaries (GBs) is used in design to stabilize nanocrystalline alloys. While analyzing GB segregation energy as a spectrum allows for a more in-depth analysis of the effects of GB atomic structure on solute segregation, this method inherently ignores solute-solute interaction by nature of considering one solute at a time. Here we develop an efficient molecular statics (MS) algorithm for determining the local effect of solute-solute interaction on GB segregation. We apply this algorithm to a Σ9 (221) symmetric tilt grain boundary in a bicrystal as well as a randomly oriented polycrystal for Ni and Cu solutes …

Emergence Of Elasto-Inertial Turbulence In 2d Natural Convection Flow With Polymer Additives, Fuqian Yin

Graduate College Dissertations and Theses

Elasto-Inertial Turbulence (EIT) is a recently discovered state of chaos triggered by the addition of polymers in a liquid flow. Its presence in wall-bounded parallel flows, pipe and channel flows, has been well-established. The present research investigates the existence of EIT in large circulations, specifically the Rayleigh-B\'{e}nard cells (RBC) caused by natural convection between two horizontal plates with a negative temperature gradient. The method of investigation is high-fidelity two dimensional direct numerical simulation of the constitutive polymer model FENE-P. The flow parameter space is mostly subcritical, characterized by $Ra$, Rayleigh number, below or equal to $10^6$, which loosely defines the …

Active Acoustic Sensing Technologies For Practical Uav-Based Condition Assessment Of Underside Bridge Decks, Damien Garland

Graduate College Dissertations and Theses

Reinforced concrete bridge decks are high performance structural elements that must survive decades of harsh mechanical and environmental loads. The structural health monitoring of bridges is a primary enabler of safe and cost-effective performance, relying on frequent inspections and repairs as needed. The undersides of concrete bridge decks are oft-overlooked areas of inspection, owing to a hard to reach and difficult location to access. Exacerbating factors to the degradation of concrete bridge decks are the freeze-thaw cycle and salt water related corrosion common in the world’s Northern climates. As concrete weathers, it decays. Corrosion induced cracking and delamination are primary …

Pymoocfd - A Multi-Objective Optimization Framework For Cfd, George Martin Cunningham Love

Graduate College Dissertations and Theses

Modern computational resource have solidified the use of computer modeling as an integral part of the engineering design process. This is particularly impressive when it comes to high-dimensional models such as computational fluid dynamics (CFD) models. CFD models are now capable of producing results with a level of confidence that would previously have required physical experimentation. Simultaneously, the development of machine learning techniques and algorithms has increased exponentially in recent years. This acceleration is also due to the widespread availability of modern computational resources. Thus far, the cross-over between these fields has been mostly focused on computer models with low …

On The Enhancement Of Penetrating Radar Target Location Accuracy With Visual-Inertial Slam, Joshua Girard

Graduate College Dissertations and Theses

This paper presents research concerning the use of visual-inertial Simultaneous Localization And Mapping (SLAM) algorithms to aid in Continuous Wave (CW) radar target mapping. SLAM is an established field in which radarhas been used to internally contribute to the localization algorithms. Instead, the application in this case is to use SLAM outputs to localize radar data and construct three-dimensional target maps which can be viewed in augmented reality. These methods are transferable to other types of radar units and sensors, but this paper presents the research showing how the methods can be applied to calculate depth efficiently with CW radar …

Medical Applications Of Ultrasound: T-Cell Drug Delivery, Osteoporosis Diagnosis, And Biofilm Mitigation, Alina Karki

Graduate College Dissertations and Theses

The ability of ultrasound to localize acoustic energy deposition and induce a biological effect within a target is examined in three novel biomedical applications: sonoporation, osteoporosis diagnosis, and biofilm mitigation.Ultrasound can excite encapsulated microbubbles, causing an acoustic cavitation effect in the vicinity of cells, temporarily increasing membrane permeability, and allowing cells to uptake foreign molecules. This non-viral transfection technique is called sonoporation. Our experimental study demonstrated that it could be effective for small interfering RNA (siRNA) delivery into an isolated mouse and human T-cells, which is a complex process despite its importance in treating numerous diseases. T-cells are non-proliferating, while …

The Optimization Of Rifle Barrel Harmonics, Daniel O'Neil

Graduate College Dissertations and Theses

From the optimization of mechanical systems perspective, firearms offer a plethora of complex scenarios. Many variables, coupled with sometimes unstable systems, must be balanced appro- priately by the user to achieve precision, that is to say, to hit the target bullseye from some distance away with a small projectile launched on a parabolic trajectory. The sources of error entirely affect final terminal precision, some of them related to human factors, others related to the quality of the ammunition, and the remaining associated with the mechanical capability of the weapon. This thesis documents the vibrations analysis of an isolated rifle barrel, …

Constraint-Aware And Efficiency-Aware Control Of Air-Path In Fuel Cell Vehicles, Eli Bacher-Chong

Graduate College Dissertations and Theses

Fuel cell technology offers the potential for clean, efficient, robust energy productionfor both stationary and mobile applications. But without fast and robust control systems, fuel cells cannot hope to maintain real-life efficiencies near enough to their theoretical potential. This work studies control and constraint management techniques to regulate a nonlinear multivariable air-path system for a proton exchange membrane fuel cell (PEMFC). The control objectives are to avoid oxygen starvation, run at the maximum net efficiency, achieve fast tracking of air flow and pressure set-points, and be easy to calibrate. To operate at maximum efficiency, a set-point map is generated for …

Finite Element Deformation Of Silver Nanowire Networks, Akiva Gopalkrishnan

Graduate College Dissertations and Theses

Tin doped Indium oxide currently is the dominant material used in the field of transparent electronics (TE) but suffers from Indium scarcity and brittle failure under small deformations. Silver Nanowires (AgNWs) are of considerable research interest due to their relative ease of fabrication, high conductivity, and mechanical ductility, as well as high corrosion stability. Existing research on single AgNWs via nanomechanical testing has shown an increase in the strength and ductility as both the diameter and gauge length is reduced, or a “smaller is stronger effect”. The formation of a network structure of AgNWs on flexible plastic substrates is essential …

Chitosan-Based Shrinking Fibers For Post-Cure Stressing To Increase Durability Of Concrete, Diarmuid Gregory

Graduate College Dissertations and Theses

Concrete is a ubiquitous building material with an extensive history, yet it has a fair number of imperfections. Its sizeable environmental impact, low tensile to com- pressive strength ratio, and lack of durability leave room for innovation. Concrete durability frames the motivation for this research.This thesis presents the motivation, methods, and findings of tests performed to quantify the durability of concrete reinforced with automatically shrinking chitosan- based fibers. A literature review, the procedures for synthesizing chitosan fibers, and preliminary tests of the control fibers are all discussed. Two different types of durability tests were carried out: rapid freezing and thawing …

Measurement On Stress-Time Avalanches Of Fiber Reinforced Concrete Beams During Flexure, Zhuang Liu

Graduate College Dissertations and Theses

Stress variations of loading histories on fiber reinforced concrete beams during flexure was investigated in this dissertation. A new experimental system was developed to collect the stress-time curves at 100 kHz sampling rate to measure temporal profiles in high resolution. Concrete beams prepared at the early age of seven days with different fiber types and fiber volume fractions were loaded at various rates during four-point bending tests. The four types of fiber used to make reinforced concrete were: steel fibers, basalt fibers, polypropylene (PP) fibers and recycled polyethylene terephthalate (PET) fibers. Stress drops induced by interactions between fibers and cementitious …

Strengthening Mechanisms In Nanocrystalline Silver-Nickel Nanolayered Materials, Malcolm Ryan Pringle

Graduate College Dissertations and Theses

Among all metals, silver has the highest electrical conductivity but also is one of the softest materials under mechanical deformation. Therefore, developing means and methods for strengthening silver without reducing conductivity is critically important for its use as a conductive electrode material in various engineering applications such as solar cells and touchscreen displays. This thesis presents a molecular-dynamics simulation study of strengthening mechanisms by intercalating nanocrystalline silver films with amorphous nickel layers, characterizing the structure of nanolayered material prototypes obtained by sputtering deposition technique. The objectives of the thesis are three-fold: To study the effects of Ni layer thickness and …

3d Acoustic Pipe Locator Imaging Based On Finite Element Analysis, Yi Liu

Graduate College Dissertations and Theses

A more complex underground pipe system is growing with the expansion of cities. However, there is no comprehensive database of underground pipes. Thus, it is urgent to build database with materials, positions, diameters, and etc. To locate the pipes is the first step. There are many ways to find pipes such as metal detector, ground penetrating radar, and acoustic method. Metal detectors are becoming increasing ineffective with more and more nonmetal is using in pipes. Ground penetrating radar is a precise way to find pipes but it is only works well under low moisture environment. Additionally, ground penetrating radar is …

Characterization Of Pressure And Temperature Reactions In An On-Demand Pressurization System For Small Satellite Propulsion, Anna M. Humphreys

Graduate College Dissertations and Theses

With the popularity of small satellites on the rise in the aerospace industry, the need for propulsion systems developed specifically for small satellite applications is ever-present. An emerging subsection of the small satellite field is CubeSats, which are cubic satellites measuring 10cm per side and weighing less than 1.33kg. At launch, CubeSats are fixed to a larger rocket but are deployed once in orbit and must rely on their own propulsion system for orbit control and maneuverability. While propulsion systems exist for rockets and satellites that are orders of magnitude larger, these traditional systems are often too bulky and complex …

A Peridynamic Simulation Of Repeated Projectile Impacts On A Steel Plate, Jacob Williams

Graduate College Dissertations and Theses

Understanding multi-projectile impact events is important for a wide range of military and aerospace applications. However, experimental studies in this field remain technologically challenging. In this thesis, simulations of two 20 mm caliber projectiles impacting a steel target above the ballistic limit were performed. Peridynamics, a non-local, particle-based computational method, was used to simulate the impacts. The spacing between the two impacts on target was varied to study the effects on projectile residual velocity, projectile deformation, and fragmentation. To optimize the Peridynamic parameters, the simulation results from a single impact were compared to experimental data available in the literature. Methods …

Carbon Monoxide Measurements In A Co2 Plasma Using Two-Photon Laser Induced Fluorescence, Brandon Voll

Graduate College Dissertations and Theses

Uncertainties in surface catalytic reaction rates in a CO2 plasma have led to overdesign of thermal protection systems, which has caused planetary entry vehicles for the Martian atmosphere to be heavier than necessary. This, in turn, has decreased the available payload of various missions. A better understanding of these reaction rates will allow more precise development of thermal protection systems leading to safer and more effective atmospheric entry vehicles. Near wall measurements in a plasma facility using laser spectroscopic techniques with sub-millimeter spatial resolution provide a method to determine surface-catalyzed reaction efficiencies over metallic surfaces. The present work includes laser …

Towards Remote Gait Analysis: Combining Physics And Probabilistic Models For Estimating Human Joint Mechanics, Reed Donovan Gurchiek

Graduate College Dissertations and Theses

The connected health movement and remote patient monitoring promise to revolutionize patient care in multiple clinical contexts. In orthopedics, continuous monitoring of human joint and muscle tissue loading in free-living conditions will enable novel insight concerning musculoskeletal disease etiology. These developments are necessary for comprehensive patient characterization, progression monitoring, and personalized therapy. This vision has motivated many recent advances in wearable sensor-based algorithm development that aim to perform biomechanical analyses traditionally restricted to confined laboratory spaces. However, these techniques have not translated to practical deployment for remote monitoring. Several barriers to translation have been identified including complex sensor arrays. Thus, …

Characterization Of The University Of Vermont Plasma Torch And Simulation Of Pyrolysis Gas And Plasma Interactions, Precious Jagun

Graduate College Dissertations and Theses

In previous studies done at the University of Vermont’s Inductively coupled Plasma (ICP) touch facility, the plasma conditions were always assumed to be in Local Thermodynamic Equilibrium(LTE) state. To improve the knowledge of the thermodynamic properties of the plasma conditions, in this study, experiments and analysis were conducted to determine whether or not the facility is indeed in LTE. LIF data was collected at 7mm off the exit of the quartz tube and compared with CEA simulations for the same plasma conditions. The facility was also better characterized by using LTE analyses of the absolute emission intensities to determine the …

Economic Efficiency And Carbon Emissions In Mes With Flexible Buildings, Zach Lawrence Hurwitz

Graduate College Dissertations and Theses

Multi-energy systems offer an opportunity to leverage energy conversion processes and temporary energy storage mechanisms to reduce costs and emissions during operation of campuses, cities, and buildings. With increasing options for flexibility in demand-side resources it is possible to meet demand without sacrificing comfort and convenience of MES occupants.

This Thesis develops a multi-period, linear optimization model of an MES with flexible buildings that captures nonlinearities in the efficiency of energy conversion processes. The flexible buildings are parametrized, in part, based on historical data from a college campus in Vermont, USA. The idea of the MES model is to investigate …

A State Estimation Framework For Fatigue Monitoring And Prognosis Of Minimally Instrumented Structural And Biomechanical Systems, Benjamin Leblanc

Graduate College Dissertations and Theses

Fatigue damage is the continuous degradation of a material, primarily due to the formation of microcracks and resulting from the repeated application of stress cycles. Traditionally a fatigue analysis was performed during the structural design stage of a machine or structure; however, more recently there has been increased interest in the monitoring and prognosis of fatigue damage in existing and operating structures. In monitoring, the structure already exists and its mechanical properties can be estimated by processing sensor measurements and non-destructive testing. The traditional approach to fatigue monitoring is to carry out a visual inspection, find macroscopic cracks and then …

Using Dielectric Characterization To Study Transport And Thermal Properties Of Gas/Supercritical Fluid Embedded Polymer Solution, Xiangxiao Yao

Graduate College Dissertations and Theses

Gas/supercritical fluid (SCF) and polymer mixtures are applied broadly in industry, such as rigid and light foam products for aircraft use, foamed cushion in chairs or shoes, and gas separation membranes for capturing methane from landfill gas. To understand the gas transport properties and polymer thermal properties of the mixture, we detected the dielectric properties of the mixture at two conditions and developed a novel self-designed system for high temperature and high pressure measurement.

The transport properties of physical blowing agents in polymers is viewed as a critical parameter controlling the final foam product’s foam density, cell density, and cell …

Subsurface Sensing With Shakers And Inspection Vehicles, Jonathan Robert Burton

Graduate College Dissertations and Theses

This research furthers the capability and understanding of subsurface sensing techniques. Proper inspection of small culverts can prevent roadway failures, major traffic disturbances and save tens of thousands of dollars on costly repairs. The Vermont Agency of Transportation (VTrans) has adopted a policy requiring all culverts to be inspected every 5 years, resulting in around 9,600 small culverts needing to be inspected annually. Having the proper equipment available to efficiently and effectively inspect small culverts at an affordable price is crucial for road infrastructure maintenance. In this thesis, an inspection vehicle is optimized for efficient and effective small culvert inspection. …