Engineering Commons^™

Quasilinear Control: Multivariate Nonlinearities, Robustness And Numerical Properties, And Applications, Sarnaduti Brahma

Graduate College Dissertations and Theses

Quasilinear Control (QLC) is a theory with a set of tools used for the analysis and design of controllers for nonlinear feedback systems driven by stochastic inputs. It is based on the concept of Stochastic Linearization (SL), which is a method of linearizing a nonlinear function that, unlike traditional Jacobian linearization, uses statistical properties of the input to the nonlinearity to linearize it. Until now in the literature of QLC, SL was applied only to feedback systems with single-variable nonlinearities that appear only in actuators and/or sensors. In this dissertation, my recent contributions to the literature of QLC are summarized. …

The Food-Energy-Water Nexus, Embodied Injustices, And Transboundary Sustainability, Sonya Ahamed

Graduate College Dissertations and Theses

Intersections of food, energy, and water systems (the FEW nexus) pose many sustainability and governance challenges, including risks to ecosystems, inequitable distribution of benefits and harms across populations, and reliance on distant sources for food, energy, and water. Nexus-based approaches can offer more holistic pathways for societal transitions to FEW systems that are just and sustainable, but tend to focus narrowly on inputs (e.g. water ‘for’ energy) in ways that do little to address the historical roots and structural underpinnings of current system inadequacies, thus risking their perpetuation.

This dissertation widens the FEW nexus in two contexts in which the …

Exploring Hidden Networks Yields Important Insights In Disparate Fields Of Study, Laurence Clarfeld

Graduate College Dissertations and Theses

Network science captures a broad range of problems related to things (nodes) and relationships between them (edges). This dissertation explores real-world network problems in disparate domain applications where exploring less obvious "hidden networks" reveals important dynamics of the original network.

The power grid is an explicit network of buses (e.g., generators) connected by branches (e.g., transmission lines). In rare cases, if k branches (a k-set) fail simultaneously, a cascading blackout may ensue; we refer to such k-sets as "defective". We calculate system risk of cascading failure due to defective 2-sets and 3-sets in synthetic test cases of the Polish and …

Food From Somewhere: Envisioning And Practicing Aspirational Food Systems, Caitlin Morgan

Graduate College Dissertations and Theses

This transdisciplinary dissertation explores the connections between material conditions, human engagements, and the social, economic, and ecological contexts in which they exist. It investigates imaginations of a better food system, projects people have already undertaken, and what happens when their visions meet reality.

Chapter 1 weaves together diverse literature: a justification for action-oriented research and a blending of ecofeminist scholarship, agroecology and sustainable agriculture, ecological economics, systems theory and food systems scholarship, and sensory studies. These disciplines tie together through notions of embeddedness, embodiment, and the context for action, which all translate to the dissertation’s methodological approach of mixed qualitative …

Upcycling Dairy Manure Fine Solids Captured By Dissolved Air Flotation As Part Of A Phosphorus Recovery And Reuse Strategy, Katherine Keith Porterfield

Graduate College Dissertations and Theses

Dissolved air flotation (DAF) has shown potential to substantially improve phosphorus (P) mass balance on dairy farms by capturing P associated with fine solids from liquid manure, enabling new management options. However, at < 25% total solids, further dewatering and other upcycling is necessary to facilitate export of recovered fine solids off farm for use in bagged or bulk products. I generated plant foods using DAF-captured dairy manure fine solids thermally dried to 45% total solids blended with other organic residuals. Dry biomass of tomato and marigold seedlings amended with 6% v/v plant food was six-times greater than the unamended control and not significantly different from a market alternative treatment. Because thermal dewatering can be prohibitively costly, I generated a second batch of plant foods using DAF-captured dairy manure fine solids conditioned with 3, 4.5 and 6% (w/w) quicklime or lime kiln dust (LKD) and dewatered using a benchtop press for comparison with thermally dried fine solids. Tomato seedling biomass was similar for thermally dried and LKD plant foods, but quicklime plant foods had no effect compared to the unamended control. Quicklime and LKD conditioned fine solids contained approximately 30 and 10 times less plant-available P than thermally dried fine solids, respectively—likely due to precipitation of Ca-P minerals. These studies indicate that DAF-captured dairy manure fine solids could be upcycled to bagged horticultural products with substantial agronomic value, however sustainable materials drying remains a key challenge to realizing this potential.

The Effects Of Oxidized Biodiesel Fuel On Fatty Acid Methyl Ester Composition And Particulate Matter Emissions From A Light-Duty Diesel Engine, Jack Elliot Reed

Graduate College Dissertations and Theses

Diesel particulate matter (PM) is classified by the EPA as carcinogenic, with the transportation sector largely responsible these emissions within the United States. Biodiesel (B100) is derived from renewable sources, providing similar chemical composition to diesel fuel and is in the current diesel supply up to 5% across the nation. However, biodiesel has an inherent oxidation issue due to the unique mixture of fatty acid methyl ester (FAME) molecules present in the biodiesel that are not in diesel. Biodiesel oxidation can only be delayed, and the inevitable process results in changes to the original fuel composition that may alter emissions …

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 …

Optimization Of Energy-Constrained Resources In Radial Distribution Networks With Solar Pv, Mohammad Nawaf Nazir

Graduate College Dissertations and Theses

The research objective of the proposed dissertation is to make best use of available distributed energy resources to meet dynamic market opportunities while accounting for AC physics of unbalanced distribution networks and the uncertainty of distributed solar photovoltaics (PV). With ever increasing levels of renewable generation, distribution system operations must shift from a mindset of static unidirectional power flows to dynamic, unpredictable bidirectional flows. To manage this variability, distributed energy resources (DERs; e.g.,solar PV inverters, inverter-based batteries, electric vehicles, water heaters, A/Cs) need to be coordinated for reliable and resilient operation. This introduces the challenge of coordinating such resources at …

Robustness And Accuracy Bounds Of Model-Based Structural Health Monitoring, Nestor Ramon Polanco

Graduate College Dissertations and Theses

The strength and stiffness of structures degrade with time due to a combination of external forces and environmental conditions. A vehicular bridge, an offshore platform, a ship hull, or a wind turbine are examples of structures that for decades must endure cumulative degradation of their mechanical properties due to cyclic loading. Fatigue-induced damage typically starts at the exterior surface of the component unless microscopic or macroscopic imperfections are present in the material's structure. Structural Health Monitoring (SHM) provides a scientific non-destructive framework to estimate the structure's current state and remaining service life. In many model-based structural health monitoring applications, the …

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 …

Statistics Of Particle Diffusion Subject To Oscillatory Flow In A Porous Bed, Kelly Curran

Graduate College Dissertations and Theses

Enhanced diffusion of a suspended particle in a porous medium has been observed when an oscillatory forcing has been imposed. The mechanism of enhancement, termed oscillatory diffusion, occurs when oscillating particles occasionally become temporarily trapped in the pore spaces of the porous medium, and are then later released back into the oscillatory flow. This thesis investigates the oscillatory diffusion process experimentally, stochastically, and analytically. An experimental apparatus, consisting of a packed bed of spheres subjected to an oscillatory flow field, was used to study the dynamics of a single particle. A variety of statistical measures were used and developed to …

Atomistic Simulation Study Of Nickel Solute Segregation And Mechanical Behavior In Nanocrystalline Fcc, Bcc And Hcp Binary Alloys, Eve-Audrey Picard

Graduate College Dissertations and Theses

Nanocrystalline metals and alloys have been proven to possess unprecedentedly higher tensile strength than coarse-grained conventional metals. The extreme grain refinement in nanocrystalline metals, however, negatively affects these materials by reducing their ductility through grain-boundary embrittlement and shear localization mechanisms that are promoted by segregation of solute atoms to the interfaces. Different segregation behaviors described in the literature can be divided into either heterogeneous or homogeneous types. Yet current understanding of the impact of solute atom arrangements within grain boundary networks on mechanical properties of cubic and hexagonal nanocrystals remains limited. In this thesis, hybrid Monte-Carlo and molecular dynamics simulations …

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 …

Nonlinear Impedance Spectroscopy To Characterize Hole Transport And Recombination Dynamics In Organic Semiconductor Devices, Robin Rice

Graduate College Dissertations and Theses

Impedance Spectroscopy (IS) is an increasingly common technique to characterize both solid state and electrochemical systems including solar cells and light emitting diodes (LEDs). However, IS relies on a system response being linear with its input such that a time invariant impedance can be defined. This is usually achieved by a small amplitude input. However, doing so suppresses responses of the nonlinear processes which are of considerable interest to those designing and optimizing these devices, such as charge carrier recombination and space charge effects. This investigation employs the recently developed nonlinear extension to IS (NLIS) based in Fourier analysis of …

Flood Analysis Of Bridge-Stream Interactions Using Two-Dimensional Models, Rachel Seigel

Graduate College Dissertations and Theses

The 2011 Tropical Storm Irene resulted in considerable property and infrastructure damage in Vermont and neighboring states, including damages to and failure of over 300 bridges and 800 km (500 miles) of roads in Vermont alone, which brought to light the vulnerability of regional transportation infrastructure to extreme flood events. The northeastern United States is experiencing more frequent precipitation events of longer duration (i.e., extreme events). Infrastructure therefore must be able to withstand more frequent flood events of greater magnitude. It is not feasible to analyze and retrofit each structure for the rigorous hydraulic demands of extreme flood events; so …

Optimizing New In Vitro Methodologies For Assessing The Effects Of Mechanical Stimuli On Lung Cells: Implications For Lung Biology And Disease, Alicia E. Tanneberger

Graduate College Dissertations and Theses

Chronic lung diseases affect millions of people in the United States and are a leading cause of both morbidity and mortality. Studying how environmental factors affect lung cell biology and function is being increasingly recognized as a critical step in understanding lung disease pathogenesis and the development of new therapeutic approaches that combat lung diseases. These factors include lung extracellular matrix (ECM) composition and the mechanobiological factors of stiffness and cyclic mechanical strain, which during breathing, act on cells during the normal expansion and contraction of the lung. However, current methodologies for studying these factors have significant limitations and new …

Leveraging Domain Knowledge In Deep Learning Systems, Colin Van Oort

Graduate College Dissertations and Theses

Machine learning, and the sub-field of deep learning in particular, has experienced an explosion in research interest and practical applications over the past few decades. Deep learning approaches seem to have become the preferred approach in many domains, outpacing the use of more traditional machine learning methods. This transitionhas also coincided with a shift away from feature engineering based on domain knowledge. Instead, the common deep learning philosophy is to learn relevant features through the combination of expressive models and large datasets. Some have interpreted this paradigm shift as the death of domain knowledge. I argue that domain knowledge is …

Geomechanical, Geochemical, And Hydrological Aspects Of Co2 Injection Into Saline Reservoirs, Maziar Foroutan

Graduate College Dissertations and Theses

Carbon dioxide Capturing, and Sequestration (CCS) is a promising technique that helps mitigate the amount of CO2 emitted into the atmosphere. CCS process mainly involves capturing CO2 at the industrial plant, followed by transportation and injection into a suitable geological storage, under supercritical conditions. Saline aquifers are among the best geological storage candidates due to their availability, high storage capacity and injectivity. Despite the CCUS technology promise, several public safety concerns remain to be address, including but not limited to reservoir/wellbore stability and integrity, CO2 leakage, ground deformation (uplift) and induced seismicity.

The injected supercritical CO2 is trapped through different …

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 …

Modeling And Control For Packetized Energy Management, Adil Khurram

Graduate College Dissertations and Theses

The overarching goal in power systems operations is to deliver energy in an efficient, reliable, and economical manner. To achieve this objective, the traditional power system operating paradigm is for generation to follow variable demand. As electrification and decarbonization policies are pursued, the levels of variable, renewable generation will increase, which will require that power system operator think beyond supply follows demand. This means that one needs to consider the potential flexibility provided by, for instance, internet-enabled, connected, and responsive loads, which are part of the broad class of behind-the-meter distributed energy resources (DERs).

The research work presented in this …

Absolute Number Density Measurements Of Atomic Species In Air And Nitrogen Plasmas, Jeffrey C. Schindler

Graduate College Dissertations and Theses

A vehicle reentering Earth's atmosphere at hypersonic velocities violently compresses the air in front of it, creating a shell of plasma at the surface. This plasma imparts energy onto the vehicle's surface via convective, radiative, and chemical heating. Currently, large uncertainties in measurements of surface reaction rates lead to over-designed thermal protection systems. Improvements in the precision of these measurements could substantially decrease the weight of the heat shield, freeing up space for additional fuel or human/scientific payload. This work aims to improve current methods for measurements of atomic number densities in plasmas, so that they may be applied to …

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, …

Transient Effects In Solution-Processed Organic Thin Films, Jing Wan

Graduate College Dissertations and Theses

Due to the weak van der Waals forces between organic semiconductor molecules, the molecular packing depends sensitively on the processing methods and conditions. Thus, understanding the crystallization mechanisms during solution deposition are essential for fundamental studies and reproducible fabrication of electronic devices.The performance of Organic field effect transistors (OFETs) also depends heavily on extrinsic factors such as contact resistance and interfacial defects, which can produce a different kind of transient effect at the metal-semiconductor contact. We have observed structural transient effects during the crystallization process of two small molecule organic semiconductors made from solution. We report in situ X-ray scattering …

Quantum Simulations Of Low Dimensional Systems And Analytic Continuation Of Imaginary Time Correlation Functions, Nathan Scott Nichols

Graduate College Dissertations and Theses

For over thirty years, a long standing problem in quantum many-body physics has been to reliably extract dynamical information from imaginary time quantum Monte Carlo data. I report on a new method developed using modern evolutionary computation routines to approach this notoriously ill-posed problem. Motivation towards a solution will be presented as a brief summary of work on quantum simulations of low dimensional systems including helium on strained graphene and helium confined within rare gas plated mesoporous silica. The Differential Evolution for Analytic Continuation (DEAC) algorithm reconstructs the dynamic structure factor from imaginary time density-density correlations at zero and finite …