Engineering Commons^™

Explaining Spatio-Temporal Evolution Of Extreme Hydro-Climatic Events Using A Complex Network Framework, Somnath Mondal

All Dissertations

Severe hydroclimatic extreme events, such as droughts, heatwaves, and heavy rainfall, are occurring with increasing frequency and causing significant impacts on both people and the environment. These events also compound in space and time, leading to even more significant consequences. Therefore, it is essential to comprehend these phenomena' concurrent and time-delayed progression across different temporal and spatial scales to address adaptation and mitigation effectively. To accurately understand and map the co-evolution of extreme events, it's necessary to have a thorough grasp of their spatiotemporal patterns, how they propagate and interact with one another, and the underlying mechanisms driving their occurrence. …

Assessing Hardware Security Threats Posed By Hardware Trojans In Power Electronics, Quinn Kinzie

All Theses

This study investigates the threat of hardware Trojans (HTs) in power electronics applications, a rising concern due to the growing demand for cost-effective embedded solutions in power systems. With the supply chain for electronic hardware devices expanding globally, particularly to low-cost foundries in foreign locations, there is an increasing risk of HT attacks. While there has been extensive research on HTs in computer applications, little consideration has been given to their threat in power electronics. This study demonstrates the effectiveness of a power electronics HT by implementing a novel HT design into a gate drive circuit. Additionally, the research proposes …

Investigation Of Geopolymer Based Soil Stabilization Methods For Expedient Airfield Pavement Surfaces, Brett Albertson

All Theses

The United States Air Force (USAF) has the unique capability of being able to interdict superior airpower anywhere, at any time. However, superior airpower is only as effective as the amount of time an aircraft can spend in a particular area. The closer an aircraft can get to the mission need, the more time that can be spent in the air, or the less time that must be spent moving in and out of the operational area. Through the use of skilled and experienced men and women, the USAF is able to apply expedient and unsurfaced airfield paving techniques that …

Mysteerio: Multi-Regional Environmentally Extended Input-Output Model For United States, Yash Srivastava

All Theses

This research work titled My State Environmentally Extended Regional Input-Output (MYSTEERIO) is based on the concept of multi-regional environmentally extended input-output (MREEIO), which is a combination of lifecycle thinking and economics principles. Numerous studies have highlighted the advantages of using this methodology to determine the environmental impacts associated with economic activities for a region. However, no prior attempt has been made to conduct a state-level analysis for the US. This research work thus tries to estimate the impacts embodied due to the consumption of goods and services at the state level by using the MREEIO principles. Extensive coverage of the …

Iron Phosphate Glass For The Immobilization Of Dehalogenated Salt Waste, Matthew Aaron Page

All Theses

Electrochemical reprocessing can be used to recycle presently stored nuclear fuel and consists of dissolving that used fuel in molten salt and the waste produced from these processes is a small amount of a high-level salt waste. Vitrification has been selected as the primary means of safely disposing high and low level radioactive waste. This is due to glass’ ability to incorporate many elements within its matrix, and it is chemically durable with the addition of network formers and other glass forming chemicals. With over 90,000 tonnes of nuclear waste in the United States, the avoidance of additional steps required …

Koopman Operator Theory And The Applied Perspective Of Modern Data-Driven Systems, Alex Krolicki

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Recent theoretical developments in dynamical systems and machine learning have allowed researchers to re-evaluate how dynamical systems are modeled and controlled. In this thesis, Koopman operator theory is used to model dynamical systems and obtain optimal control solutions for nonlinear systems using sampled system data. The Koopman operator is obtained using data generated from a real physical system or from an analytical model which describes the physical system under nominal conditions. One of the critical advantages of the Koopman operator is that the response of the nonlinear system can be obtained from an equivalent infinite dimensional linear system. This is …

Performance Based Design And Machine Learning In Structural Fire Engineering: A Case For Masonry, Deanna Craig

All Theses

The volatile and extreme nature of fire makes structural fire engineering unique in that the load actions dictating design are intense but not geographically or seasonally bound. Simply, fire can break out anywhere, at any time, and for any number of reasons. Despite the apparent need, fire design of structures still relies on expensive fire tests, complex finite element simulations, and outdated procedures with little room for innovation. This thesis will make a case for adopting the principles of performance-based design and machine learning in structural fire engineering to simplify the process and promote the consideration of fire in all …

Microcosm Evaluation Of Natural And Biologically-Enhanced Abiotic Transformation Of Chlorinated Ethenes In Low Permeability Formations, Hao Wang

All Dissertations

Trichloroethene (TCE) is one of the most commonly found hazardous compounds at Superfund sites, especially in groundwater. Its volatility and toxicity pose a threat to drinking water safety and human health. In the past decades, research on the fate of TCE in the environment has shifted to contamination of low-permeability formations, for example fractured bedrock aquifers. TCE back-diffusion from low permeability zones and management of persistent TCE groundwater plumes caused by this long-term source zone pose major challenges for remediation.

Monitored natural attenuation (MNA) is a cost-effective remediation strategy that has gradually gained acceptance by regulators. Compared to extensive active …

Design, Fabrication, And Characterization Of Conjugated Polymeric Electrochemical Memristors As Neuromorphic/Integrated Circuits, Benjamin Grant

All Dissertations

Organic materials are promising candidates for future electronic devices compared to the complementing inorganic materials due to their ease of processability, use, and disposal, low cost of fabrication, energy efficiency, and flexible nature toward implementation as flexible and non-conformal devices.With that in mind, electrochemical materials have been widely demonstrated with commercial use as sensors, displays, and a variety of other electronic devices. As Moore's law predicts the increase in the density of transistors on a chip, the requirement to create either smaller transistors or the replacement of the transistor device entirely is apparent. Memory resistors, coined ``memristor", are variable resistive …

Multiscale Topology Optimization With A Strong Dependence On Complementary Energy, Dustin Dean Bielecki

All Dissertations

A discrete approach introduces a novel deep learning approach for generating fine resolution structures that preserve all the information from the topology optimization (TO). The proposed approach utilizes neural networks (NNs) that map the desired engineering properties to seed for determining optimized structure. This framework relies on utilizing parameters such as density and nodal deflections to predict optimized topologies. A three-stage NN framework is employed for the discrete approach to reduce computational runtime while maintaining physics constraints.

A continuous representation that uses complementary energy (CE) methods to solve a representative element's homogenized properties consists of an embedded structure that is …

In Vitro Bioreactor For Mechanical Control And Characterization Of Tissue Constructs, Samuel Coeyman

All Dissertations

Heart failure (HF) currently affects over 6 million Americans, 50% of whom die within 5 years of their initial diagnosis. A major contributor to the onset of HF is cardiac fibrosis in the myocardium, which arises when fibroblasts (FBs) are activated in response to heightened mechanical stress from overload conditions like hypertension. Activated FBs remodel the extracellular matrix (ECM) and secrete ECM proteins including collagen. FB remodeling has been studied in the past by applying forces and/or deformations to three-dimensional, cell-seeded gels and tissue constructs in vitro. Unfortunately, previous stretching platforms have traditionally not enabled mechanical property assessment to be …

Elucidation Of Active Site And Mechanism Of Metal Catalysts Supported In Nu-1000, Hafeera Shabbir

All Dissertations

Advances in extraction of shale oil and gas has increased the production of geographically stranded natural gas (primarily consisting of methane (C1) and ethane (C2)) that is burned on site. A potential utilization strategy for shale gas is to convert it into fuel range hydrocarbons by catalytic dehydrogenation followed by oligomerization by direct efficient catalysts. This work focuses on understanding metal cation catalysts supported on metal-organic framework (MOF) NU-1000 that will actively and selectively do this transformation under mild reaction conditions, while remaining stable to deactivation (via metal agglomeration or sintering). I built computational models validated by experimental methods to …

Influence Of Climate And Droughts On Visibility Degradation In Saudi Arabia, Saleh Alhathloul

All Dissertations

The spatial and temporal distribution of temperature and precipitation determines the availability of water resources for ecosystems. The hydrological cycle can be disrupted by differences in meteorological variables and the random nature of water demand. Horizontal visibility degradation is an indicator of the changes in local meteorological variables, rainfall deficits, and drought conditions. Long-term analysis of meteorological variables and visibility records helps understand the causes of visibility degradation. The first objective of this dissertation is to investigate the long-term variability of horizontal visibility along with metrological variables based on annual and seasonal time scales over Saudi Arabia. The second objective …

Optical Control System For Atmospheric Turbulence Mitigation, Martyn Lemon

All Theses

Propagation of laser light is distorted in the presence of atmospheric turbulence. This poses an issue for sensing, free-space optical communications, and transmission of power. With an ever-increasing demand for high-speed data communications, particularly between satellites, unmanned vehicles, and other systems that benefit from a point-to-point link, this issue is critical for the field. A variety of methods have been proposed to circumvent this issue. Some major categories include the manipulation of the light’s structure, an adaptive scheme at the optical receiver, scanning mirror systems, or a transmission of simultaneous signals with a goal to improve robustness.

There is an …

Multiple Objective Function Optimization And Trade Space Analysis, Yifan Xu

All Theses

Optimization can assist in obtaining the best possible solution to a design problem by varying related variables under given constraints. It can be applied in many practical applications, including engineering, during the design process. The design time can be further reduced by the application of automated optimization methods. Since the required resource and desired benefit can be translated to a function of variables, optimization can be viewed as the process of finding the variable values to reach the function maxima or minima. A Multiple Objective Optimization (MOO) problem is when there is more than one desired function that needs to …

Effects Of Surface Noise On Printing Artifacts: An Artistic Approach To Hiding Print Artifacts, Samuel New

All Theses

This research focuses on improving the quality of Fused Filament Fabrication (FFF) 3D printing by using fractal noise to mask certain print artifacts (e.g. layer lines and stair-stepping). The use of textures is quite common in digital sculpting for aesthetic reasons. This study focuses on finding specific textures that minimize visible 3D print artifacts.

Scalable Data-Driven Predictive Modeling And Analytics For Cho Process Development Optimization, Sarah Mbiki

All Dissertations

In 1982, the FDA approved the first recombinant therapeutic protein, and since then, the biopharmaceutical industry has continued to develop innovative and highly effective biological drugs for various illnesses¹. These drugs are produced using host organisms that are modified to hold the genetic encoding of the targeted protein¹. Of the many host organisms, Chinese hamster ovary (CHO) cells are often used due to capability to perform posttranslational modification (PTM): which allows human-like synthesis of proteins unlikely to invoke immunogenicity in humans ^1,2.

Despite all the positive attributes, many challenges are associated with CHO cell cultures, …

Non-Destructive Terrain Evaluation And Modeling For Off-Road Autonomy, Howard Brand

All Dissertations

In recent years, there has been an increased interest in implementing intelligent robotic systems in outdoor environments. Paramount to accomplishing this objective is being able to conduct successful robotic navigation in unprepared outdoor environments. This presents unique challenges in that there is a risk of catastrophic immobilization in terrain regions which, though unoccupied, cannot provide traction support for vehicle mobility. Methods for providing prior knowledge and perception of traction support is therefore an interest and focus of research.

In the advent of ever advancing machine learning models, “learn-as-you-go” approaches have emerged as topics of interest for mobility prediction. These approaches, …

Development Of A Tissue Engineered Cardiac Patch, Howard Herbert

All Dissertations

Cardiovascular Disease(CVD) is the leading cause of mortality in the developed world. CVD is most commonly manifested as atherosclerosis of the coronary arteries leading to Myocardial Infarction(MI). After MI, fibrosis of the ventricular wall leads to heart failure(HF), a pandemic affecting 26 million people globally. While therapies are continuously developed to combat HF, the treatment of choice, whole heart transplant, is limited by the availability of donor hearts. It is clear that there is a need to develop a long-term solution to combat HF and its enormous economic burden. Tissue Engineering and Regenerative Medicine holds promise as a possible solution …

Dynamic Analysis, Characterization, And Design Of Rigid-Flex Pcb Robotics, John Bell

All Dissertations

The era of space exploration is driven by and fuels large advances in technological progress.
Over the last decade, engineering practices for spacecraft, space structures, robotics, software and
hardware, manufacturing techniques, and the implementation of new and novel materials has been
revolutionized. Space exploration pushes the envelope in terms of technological capabilities and
robotic systems (rovers) become lighter, smaller, and more capable of sustaining damage. This
dissertation aids in the advancement of design knowledge for a class of rovers characterized by
their chassis architecture: rigid-flex printed circuit board (PCB) robotics. These rovers leverage
the printed circuit cards as the structural …

Modeling, Control And Estimation Of Reconfigurable Cable Driven Parallel Robots, Adhiti Raman Thothathri

All Dissertations

The motivation for this thesis was to develop a cable-driven parallel robot (CDPR) as part of a two-part robotic device for concrete 3D printing. This research addresses specific research questions in this domain, chiefly, to present advantages offered by the addition of kinematic redundancies to CDPRs. Due to the natural actuation redundancy present in a fully constrained CDPR, the addition of internal mobility offers complex challenges in modeling and control that are not often encountered in literature.

This work presents a systematic analysis of modeling such kinematic redundancies through the application of reciprocal screw theory (RST) and Lie algebra while …

Synthesis And Characterization Of Vo2 Thin Films On Piezoelectric Substrates, Samee Azad

All Theses

Polycrystalline VO₂ thin films synthesized on two piezoelectric substrates (AT-cut quartz and GaN/AlGaN/GaN/Si) using low pressure direct oxidation technique have been characterized and compared to VO₂ grown on traditional non-piezoelectric substrates sapphire and SiO₂/Si. X-ray diffraction and atomic force microscopy characterization performed on the as grown films confirmed high quality of the VO₂ films grown on both the piezoelectric and non-piezoelectric substrates. Changes in material properties associated with the semiconductor metal transition (SMT) of the VO₂ films were investigated through resistivity and transmitted optical power changes measured across the SMT. It was observed that …

Supporting Us Army Next-Generation Ground Vehicle Simulation Modeling Using An Integrated Ontology Suite, Edward Louis

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The development of the US Army’s next-generation of ground vehicle systems is supported by simulations that predict vehicle performance and inform engineering design choices in the design and acquisition process. In this paper, we describe the development of an Integrated Ontology Suite to support modeling and simulation of next generation military ground vehicles. The ontology suite is intended to address model reuse challenges and increase the shared understanding of ground vehicle system simulations. It is intended to function in a Model Library structure that stores, documents, assembles, and executes vehicle simulations. The ontology suite consists of four domain ontologies: Vehicle …

Effects Of Polymer Side-Group Size On Interfacial Mechanics Of Graphene-Polymer Nanocomposites, Grace Brokaw

All Theses

Graphene-reinforced polymer nanocomposites possess excellent mechanical, thermal, and electrical properties, which make them promising candidates for various applications. Favorable interfacial interactions and mechanics between graphene sheets and polymer matrices are often essential to achieve superior mechanical properties. Nevertheless, it remains largely elusive how molecular features of polymer systems, particularly the side-group size of polymer chains, affect the interfacial mechanics between graphene sheets and polymer matrices, primarily due to challenges in well controlling these features in experiments. On the other hand, exploring their roles in the mechanical properties of graphene-polymer nanocomposites is very expensive to study with all-atomistic molecular dynamics (MD) …

Flexural Testing Of Precast Reinforced Concrete Bridge Slabs, Evaluation Of Deterioration And Strengthening Applications, Alyssa Leaman

All Theses

This thesis investigates the strength of flat precast concrete slabs that were taken from decommissioned South Carolina bridges. The specimens tested spanned 14 ft (4.3 m) or 15 ft (4.6 m), were 5 ft (1.5 m) or 5.5 ft (1.7 m) wide, and 8.25 in (210 mm) thick. In South Carolina, there are approximately 3000 similar bridges that use these slab members. Testing was conducted to determine the flexural capacity of “typical” slabs and the residual strength of slabs having visible deterioration of both the rebar and the concrete. For the slabs that were load rated below the new standards, …

Utilizing Systematic Design And Shape Memory Alloys To Enhance Actuation Of Modular High-Frequency Origami Robots, Jessica M. Den Haese

All Theses

Shape memory alloys (SMAs) describe a group of smart metallic materials that can be deformed by external magnetic, thermal, or mechanical influence and then returned to a predetermined shape through the cycling of temperature or stress. They have several advantages, such as having excellent mechanical properties, being low cost, and being easily manufactured, while also providing a compact size, completely silent operation, high work density, and requiring less maintenance over time. SMAs can undergo sold-to-solid phase transformations, and it is because of these phase transformations that they can experience shape memory effect (SME); or the ability to recover from a …

Flexural Bond Strength Of Masonry Assemblies With Lightweight Grout, Benjamin L. Hiner

All Theses

Lightweight grout has many potential benefits in masonry construction, including minimizing mass, improving thermal performance, and potentially reducing shrinkage cracking via internal curing. However, insufficient testing of masonry assemblies with lightweight grout has been conducted to suggest appropriate design modification factors akin to the lambda factor in ACI 318-19. The objective of this paper is to study the tensile bond behavior of masonry assemblies grouted with lightweight grout and to suggest appropriate equations for predicting design capacity. A moment couple test is designed specifically for grouted masonry assemblies and has additional capacity compared to the traditional ASTM 1072 bond wrench …

Transforming Character Faces Based On Perceived Personality Traits, Kara Porter

All Theses

The ability to read other human's faces is a crucial part of everyday life. Subconsciously, the human brain analyzes someone's face within the first few seconds of seeing it, making a variety of conclusions ~\cite{FacePerp} such as gathering information about emotional state and assuming character traits this person might possess. The purpose of this thesis is to create a tool that allows a user to alter features of a character's three dimensional (3D) face mesh to look increasingly or decreasingly like the character possesses certain personality traits. Using a sample set of randomly generated faces, a survey is conducted to …

Oam-Based Wavelets In A High Speed Optical Probing System For Measuring The Angular Decomposition Of The Environment, Justin Free

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This thesis presents the theoretical development of orbital angular momentum (OAM) based wavelets for the analysis of localized OAM information in space. An optical probing system for generating and detecting these wavelets is demonstrated; individual wavelets can scan the environment in 10µs or less. The probing system was applied to a three-dimensional atmospheric turbulence distribution to obtain a continuous wavelet transform of the angular information of the turbulent propagation path about a fixed radius. An entire continuous wavelet transform was measured in 3.8ms; the measurements are much faster than the turbulence and give insight into the short time scale of …

An Application Of Optimized Bistable Laminates As A Low Velocity, Low Impact Mechanical Deterrent, Graham Lancaster

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This research considers the problem of using bistable laminates as a mechanical deterrent to the impending impact of a particle. The structure will be controlled through an algorithm that will utilize piezoelectric devices to activate them in unison with the bistable laminate to successfully deter. A novel experimental setup will be constructed to ensure that the bistable laminate stays fixed when acting as a mechanical deterrent. Piezoelectricity is the main driving force of the bistable laminate to morph and this study will use a Macro Fiber Composite (MFC) actuator that contains piezoelectric ceramic rods in a patch to transfer electrical …