Engineering Commons^™

Development Of A Converging-Channel Drop Tower For Sphere Symmetric Isolated Single Droplet Combustion, Nicholas Alexander Demaio

Theses and Dissertations

The dawn of a new Space Age is upon us; Microgravity combustion of hydrocarbon fuels is a popular method of research and characterization. This allows for a one-dimensional analysis by suppressing the buoyancy forces produced by gravity and the large temperature differential between the flame boundary and the surrounding air. The current testing methods are expensive and require extensive preparation on the researchers behalf. There is a need to investigate an alternative method that is inexpensive, repeatable, and comparable to the other approaches that coincides with the literature.

A low-cost converging-channel drop tower was designed and fabricated for sphero-symmetric single …

Combined Effects Of Welding Residual Stress And Thermal Expansion In Cwr, Brennan Gedney

Theses and Dissertations

Continuously welded rail with flash-butt welded joints has become standard practice for railway construction around the world. Through the process of welding, a residual stress field develops in the joint which typically remains in the rail through its service life. Consequently, the total stress is altered locally in the presence of operation induced stresses. One such stress develops due to thermal expansion of the rail during the daily and seasonal solar radiation heating cycle. This paper seeks to ascertain the combined effects of welding residual stress with thermal expansion through computer simulations. This is aimed at two objectives: determining whether …

Computer Vision-Based Automatic Railroad Crossing Monitoring And Track Inspection, Feng Guo

Theses and Dissertations

Currently, there are many imminent challenges in the railroad infrastructure system of the United States, impacting the operation, safety, and management of railroad transportation. In this work, three major challenges which are overcrowded traffic congestion at the grade crossing, low-efficiency and accuracy on inspection of missing or broken rail track components, and dense rail surface defects without quantification, respectively are studied. The congested railroad grade crossing not only introduces significant traffic delays to travelers but also brings potential safety concerns to the first responders. However, limited studies have been devoted on developing an intelligent traffic monitoring system which is significant …

Evaluation Of A Trigonometric Grey Model For Estimating And Predicting Pavement Condition, Amara Kouyate

Theses and Dissertations

States, counties, and municipalities rely on pavement performance curves to forecast future pavement conditions in their jurisdictions. Accurate prediction is essential for budget planning and the identification of candidates for rehabilitation. This study investigates the use of a grey model (GM) to estimate and predict pavement conditions. An advantage of the GMs is that they do not require a large sample size for model estimation. This aspect is important since smaller towns and municipalities often cannot afford to collect pavement condition data frequently due to cost. There are other situations where sample size may be limited, such as using project-level …

Fine Points For Broad Bumps: The Extension Of Rietveld Refinement For Benchtop Powder Xrd Analysis Of Ultra-Small Supported Nanoparticles, Jeremiah W. Lipp

Theses and Dissertations

The goal of this work is to demonstrate the capabilities of benchtop Bragg diffraction in characterizing ultra-small (< 2nm) nanoparticles. To this end we have established a method for accurately separating the background, adjusting for relevant intensity effects, and analyzing the results with Rietveld refinement. This method is applied to the characterization of six silica-supported “noble” metals under ambient conditions: Pt, Pd, Ir, Rh, Ru, and Au. Surprisingly, Bragg diffraction is capable of shining light on this difficult-to-characterize size region – revealing the propensity of these metal nanoparticles to oxidize at room temperature. Preliminary findings for future work are also discussed: extending our method to crystalline supports and fluorescent samples.

Development Of A Rapid Compression And Expansion Machine To Characterize The Ignition Propensity Of Multi-Component Liquid Fuels, Jonathan Joseph Morreale

Theses and Dissertations

Combustion has been the primary source for energy production, whether it be from coal, oil, or natural gas, for a very long time. With increasing population and therefore an increased demand for energy, efficiency is becoming a concern. In order to increase efficiency, engines have been downsized and compression ratios have been increased. In doing so, problems have arisen such as knock and low speed pre-ignition. To better understand these problems, an investigation into how fuels ignite at higher pressures is necessary. Real fuels are comprised of multiple components that exhibit significant variations in their own physical and chemical characteristics. …

Searching Extreme Mechanical Properties Using Active Machine Learning And Density Functional Theory, Joshua Ojih

Theses and Dissertations

Materials with extreme mechanical properties leads to future technological advancements. However, discovery of these materials is non-trivial. The use of machine learning (ML) techniques and density functional theory (DFT) calculation for structure properties prediction has helped to the discovery of novel materials over the past decade. ML techniques are highly efficient, but less accurate and density functional theory (DFT) calculation is highly accurate, but less efficient. We proposed a technique to combine ML methods and DFT calculations in discovering new materials with desired properties. This combination improves the search for materials because it combines the efficiency of ML and the …

An Investigation Of The Ignition Propensities Of Fuels Perturbed By Nitrogen Monoxide, Ackmer Robinson Iii

Theses and Dissertations

Quantitative structure property relationship (QSPR) regression models were developed based on the chemical functional group distribution of toluene reference fuels (TRF, mixtures of n-heptane, iso-octane, and toluene) for RON, MON, and DCN. The QSPR regression models were developed using DCN measurements from this study as well as RON/MON data available in literature. The correlations between RON/MON and DCN were analyzed. The ignition propensity of TRFs perturbed by NO addition was also investigated in this study. The interactions between the chemical functional groups and NO were investigated using an ignition quality tester (IQT). It was found that the increase in the …

Mathematical Model For Sei Growth Under Open-Circuit Conditions, Wei Shang

Theses and Dissertations

An irreversible capacity loss will take place in lithium ions batteries due to the solid electrolyte interface (SEI) creating, which consumes the active lithium and reduces solvent. SEI is either good since it can prevent further electrolyte decomposition or bad for lessening batteries' lifetime. Mathematical modeling of SEI formation is done within a porous electrode to model an empirical battery in the x-direction.A solid electrolyte interphase (SEI) growth model is developed in a mixed-mode which contains solvent diffusion through the SEI layer and its corresponding kinetics of solvent reduction at the electrode surface. The governing equations are numerically solved by …

A Novel Model To Study Adipose-Derived Stem Cell Differentiation, Austin N. Worden

Theses and Dissertations

The use of three-dimensional (3D) culture systems (hydrogels) and adipose-derived stem cells (ADSCs) in regenerative medicine to advance early-stage investigation and modeling of the mechanisms of diseases, treatments, targets, etc. has recently increased. ADSCs, specifically, are utilized due to their innate programming during embryogenesis and in adult tissues in addition to their ability to differentiate into mesodermal, endodermal, and ectodermal cell-specific lineages. Of importance is that these advancements do not involve a model specimen (i.e. mice or rats) and simulate the numerous conflicting signals a migrating cell is exposed to in vivo such as chemokines, extracellular matrix (ECM), growth factors, …

Preparation, Characterization And Evaluation Of Rationally Designed Catalysts By Electroless Deposition, Wen Xiong

Theses and Dissertations

In heterogeneous catalysis, it is a proven factor that the surface-specific activity and the catalyst selectivity strongly depends on the active sites which are determined by the composition, size, and shape of the particle. For structure-sensitive reactions favored by specific surface sites, such as corners, steps, or edges, TOF and selectivity can be greatly changed by the size of catalyst particles since the active site distribution will change with the size of the catalysts. Usually, metal particles are synthesized by two methods in industry, namely precipitation and impregnation, which often exhibit a broad size distribution. The grand challenge of colloidal …

Operating Strategies And Disturbance Characterization For Dc Microgrids, Miles Leonard-Albert

Theses and Dissertations

The present state of the electrical grid is unable to meet the demands of transmission. Digital twin technology provides a promising solution to this problem by allowing for analysis and control of distributed energy resources. This thesis presents initial work towards development of a digital twin for a DC power system. Two versions of the DC power system are created and evaluated against randomly generated load profiles. System performance is evaluated on the basis of the quantity of the load that is unserviced by the generation and energy storage. Energy storage operating strategies that modify the model to prioritize different …

Nonlinear Intelligent Model Predictive Control Of Mobile Robots, Benjamin Albia

Theses and Dissertations

This thesis presents a framework for an artificial neural network (ANN) model-based nonlinear model predictive control of mobile ground robots. A computer vision analysis module was first developed to extract quantitative position information from onboard camera feed with respect to a prescribed path. Various strategies were developed to construct nonlinear physical plant models for model predictive control (MPC), including the physics-based model (PBM), the ANN trained on PBM-generated data, the ANN trained on test-captured data, and the ANN initially trained on PBM-generated data and then retrained with captured data. All the models predict physical states and positions of the robot …

Leveraging Digital Transformation To Build The Technology Of Tomorrow Using Yesterday’S Equipment, Evan Barnett

Theses and Dissertations

Today’s industry sectors are filled with machines developed years ago. Healthcare, manufacturing, sustainment operations, and many others have equipment that may be reliable, but lacks certain capabilities that the newest technology delivers. The digital environment is becoming a necessity for users who want greater insights into how to improve their processes. A solution to this problem would be to purchase the newest equipment that contains robust measures to generate, collect, and analyze data. However, this solution may not be financially feasible for some and for others may sacrifice machine downtime and reliability. To combat these issues, this research focuses on …

From The Surface To The Reactor: Identifying The Active Sites For Propane Dehydrogenation On Platinum-Based Catalysts Through Density Functional Theory, Experimental Data, And Uncertainty Quantification, Charles Henry Fricke

Theses and Dissertations

Propane dehydrogenation is a critical process of producing propylene, an important feedstock for the chemical industrial. There are multiple key processes to produce propylene in this manner, but one of the largest processes involves non-oxidative dehydrogenation on a platinum-tin alloy based catalyst. In general, these reactions and catalytic particles are complex, with many dehydrogenation, cracking, and reforming reactions taking place during these processes on multiple surfaces. With this in mind, ab initio computational catalysis models are used to generate further insight into these catalytic processes. In this dissertation, there are three aims to be solved: identifying the most likely active …

The Effect Of Low Dose Penicillin On Tumor Development In ApcMin/+ Mice, Kinsey Ann Sierra Meggett

Theses and Dissertations

Antibiotics have been our most effective weapon against bacterial infections since their discovery in the early 1900s. Their use has been critical in reducing mortality rate from infectious diseases. However, in the last few decades, the overuse of antibiotics, beginning at an early age and into adulthood, has become a growing concern globally. Penicillin is one of many extensively used antibiotics in early childhood that has been used to treat childhood infections. Recent studies showed that exposure to low dose penicillin can have adverse effects leading to chronic illness such as diabetes, allergies, inflammation, and susceptibility to obesity, with the …

The Role Pde11a4 Signaling And Compartmentalization In Social Behavior, Kaitlyn Pilarzyk

Theses and Dissertations

People tend to be social by nature. Being socially connected not only helps people live longer and healthier lives, but being an engaged and contributing member of society strengthens our communities overall. Maintaining intact social behaviors is key to maintaining this wellbeing, with disruptions negatively affecting both mental and physical health. Indeed, social isolation and feelings of loneliness can significantly increase a person’s risk of premature death, heart disease, and stroke as well as depression, anxiety, suicide, and dementia. Maintaining the ability to create and store social memory with age is, therefore, key to maintaining proper social behaviors. Unfortunately, individuals …

Recent Advances In Catalytic Ethylene Epoxidation: Synthesis, Characterization, And Evaluation, Benjamin Thomas Egelske

Theses and Dissertations

First synthesized in 1859 by French chemist Charles-Adolphe Wurtz, ethylene oxide (EO) is produced from the direct epoxidation of ethylene and molecular oxygen over a low surface area α-Al₂O₃ supported silver (Ag) catalyst [1-6]. With a production capacity over 35 Mt/year, EO is the largest chemical by volume synthesized from a heterogeneously catalyzed process and is used in the production of ethylene glycol, ethoxylates, and ethanolamines [6, 7]. State-of-the-art catalyst formulations contain high loadings of Ag, typically 12-30wt%, required to recover activity in the presence of promoter elements which increase EO selectivity from ~75% for unsupported Ag to 80% for …

Impact Of Graphene On Microstructure And Compressive Strength Of Cement Mortars Utilizing Two Different Dispersion Methods, Elhussien Khaled Elbatanouny

Theses and Dissertations

Carbon-based nanomaterials are currently used to reinforce cement-based composite materials based on their superior properties. This study investigates the mechanical property (compressive strength) of cement mortars incorporated with pristine graphene. The dosages of graphene materials used were 0.01%, 0.02%, 0.03%, and 0.04% by weight of cement. Moreover, this study compares two dispersion techniques: ultrasonication with surfactant coating and mechanical blending with surfactant coating to promote the use of graphene in cement mortars. A commonly used polycarboxylate superplasticizer Sika-Viscocrete Ultra 2100, was used as a dispersant agent (surfactant) of graphene with a surfactant to graphene weight ratio of 9 to 1. …

Structure And Stability Of Ag-Ir Bimetallic Catalysts Prepared By Electroless Deposition And Synthesis And Performance Of High Selectivity Movnbsbteox Mixed Oxides For Oxidative Dehydrogenation Of Ethane, Mozhdeh Parizad

Theses and Dissertations

Improvements in industrial thermal conversions can be realized through comprehensive catalytic studies, where enhanced catalyst stability and activity are desired. Catalyst performance can be greatly affected by structural changes at high temperatures. In the case of supported Ag-Ir particles, the surface free energy (SFE) can determine preferred arrangement of the component metals. The well-established methods of strong electrostatic adsorption (SEA) and electroless deposition (ED) have been used to synthesize highly-dispersed Ag/Ir on different alumina supports (δ,θ-Al2O3 and γ-Al2O3). Surface thermodynamics dictate that the Ir-Ag system should conform to minimize free energy resulting in a low SFE Ag layer localized on …

Predicting Pavement Structural Condition Using Machine Learning Methods, Nazmus Sakib Ahmed

Theses and Dissertations

State departments of transportation recognize the need to incorporate pavement structural condition in their pavement performance models and/or decision processes used to select candidate projects for preservation, rehabilitation, or reconstruction at the network level. However, pavement structural condition data are costly to obtain. To this end, this paper develops and evaluates the effectiveness of two machine learning methods, Random Forest (RF) and eXtreme Gradient Boosting (XGBoost), for predicting a flexible pavement’s structural condition. The aim is to be able to predict whether a pavement section’s structural condition is poor or not based on Annual Average Daily Traffic (AADT), truck percentage, …

Identification Of Structural Signature Responses From Response Time Histories Using B-Spline Impulse Response Techniques, Shadhan Ahmed Al Kharusi

Theses and Dissertations

Structure Health Monitoring (SHM) is an essential practice for ensuring the safety of people and the structures itself. For this purpose, variety of global and local damage detection methods have been used to investigate damages. Global damage detection focus on identifying damage in early stages while local damage detection related to damage location, severity, and prediction of the remaining of the structure. Any damage in structure leads to a change to the properties and characteristics of the dynamic response.

Existing methods uses modal-based and response-based for damage detection. Both have several shortcoming associate with sensitivity of the damage and measurement …

Development Of A First-Generation Prototype Laboratory System For Rail Neutral Temperature Measurements, Ellie Yi-Hsien Chao

Theses and Dissertations

Modern railway tracks worldwide standardize the use of Continuous Welded Rail (CWR) due to its ability to prevent disadvantages associated with rail joints in a track. CWR is laid when the rail is free of thermal stresses, also known as Rail Neutral Temperature (RNT). RNT is controlled in the CWR installation procedure; however, over time, the temperatures deviate from the RNT. The deviation causes significant thermal stresses introduced in the longitudinal direction of the rail, leading to potential failures such as pull-apart and buckling, causing track integrity and safety of train operation. The most significant potential failure is track buckling …

Fabrication And Characterization Of Micro/Nanostructured Ceramic Device For Energy Conversion, Yun Gan

Theses and Dissertations

The deteriorating climate is threatening our living habitat and arousing public awareness. To achieve the carbon neutral goal by the middle of 21st century, developing novel technologies to reduce CO₂ emission or promote its capture become urgent. Among them, oxygen permeation membrane (OPM) and solid oxide cell (SOC) are two promising devices for clean energy conversion.

In chapter 1, the background of OPM and SOC are briefly introduced. Fundamental mechanism and application of phase inversion, the key process involved in fabrication of hollow fiber OPM and microtubular SOC are emphatically described. Mixed ionic and electronic conducting (MIEC) perovskites demonstrate …

Increased Detectivity And Low Temperature Performance Analysis Of Sub-20Μm Micropixel Array A1gan Uv Photodiodes, Samia Islam

Theses and Dissertations

This thesis is divided into two sections. At first, we demonstrate ~1.5x detectivity increase in AlGaN photodiodes on sapphire using distributed micropixel arrays with 5-15 µm pixel diameter. This is due to the ~10x larger chip footprint of the 5um diameter micropixel arrays compared to planar control structures with identical p contact area. The responsivity of the larger areas was the same as that of the control structure despite the larger footprint while the dark currents, an indicator of noise, remained unchanged. The photocurrent generated between pixels was collected due to transmission line effects connecting the pixels separated by 5um, …

Robot Area Coverage Path Planning In Aquatic Environments, Nare Karapetyan

Theses and Dissertations

This thesis is motivated by real world problems faced in aquatic environments. It addresses the problem of area coverage path planning with robots - the problem of moving an end-effector of a robot over all available space while avoiding existing obstacles. The problem is considered first in a 2D space with a single robot for specific environmental monitoring operations, and then with multi-robot systems — a known NP-complete problem. Next we tackle the coverage problem in 3D space - a step towards underwater mapping of shipwrecks or monitoring of coral reefs.

The first part of this thesis leverages human expertise …

Hydrodeoxygenation Of Biomass Derived Sugar Alcohols To Platform Chemicals Using Heterogeneous Catalysts, Blake Macqueen

Theses and Dissertations

This work set out to investigate biomass derived sugar alcohol upgrading via the removal of oxygen and hydroxyl groups via the hydrodeoxygenation reaction utilizing heterogeneous catalysts. The importance of reaction conditions, catalyst meal loadings, catalyst structure and properties were probed using techniques such as design of experiments, and spectroscopic techniques including Raman and DRIFTS. The state of the art simultaneous hydrodeoxygenation (S-HDO) catalyst ReO_x-Pd/CeO₂ was investigated and optimized for various sugar alcohol substrates. The kinetics and associated mass transfer were also investigated to give further insight into the reaction over the ReO_xPd/CeO₂ catalyst.

First, …

Ultrawide Bandgap Algan-Channel Metal Oxide Semiconductor Heterostructure Field Effect Transistors With High-K Gate Dielectrics, Md Abu Shahab Mollah

Theses and Dissertations

Ultra-wide Band Gap (UWBG) (E_G > 3.4 eV) Al_xGa_1-xN channel devices are promising candidates for compact next-generation power electronics due to the scaling of the breakdown field with alloy composition. The huge opportunity in consumer electronics is the major driving force behind the recent developments of UWBG AlGaN-channel HEMTs. One of the most critical issues limiting the device performance at high power level is device degradation primarily caused by gate leakage current. Use of SiO₂ gate insulator is a standard method to suppress gate leakage but it causes threshold voltage shift towards more negative requiring …

Development Of A Multi-Scale Mechano-Electrochemical Battery Model, Drew J. Pereira

Theses and Dissertations

As the automotive industry moves towards large format electric vehicles, such as trucks and SUVs, the need for highly efficient, energy-dense electrodes rapidly increases. Several promising active materials have been studied and proposed, however, many of these materials undergo significant volume change upon lithiation and de-lithiation. Cell and pack designers struggle to understand and predict how active material volume change at the particle scale will affect mechano-electrochemical behavior on the electrode, cell, and pack scales. Additionally, many of these active materials suffer in their cycle life due to a mechanically-driven degradation of the electrode matrix. Therefore, the focus of this …

Catalytic And Non-Catalytic Methods For Hydrocarbon Upgrading, Valorization, And Pollutant Control, Michael Morgan Royko

Theses and Dissertations

This work investigates catalytic and non-catalytic oxidative chemical upgrading and pollutant remediation techniques to responsibly utilize hydrocarbon feedstocks with existing infrastructure as the transition to more renewable and cleaner feedstocks for energy generation are developed. These technologies include oxidative dehydrogenation of ethane, development of magnetically separable catalysts to reduce carbon monoxide emissions during biomass upgrading as well as the subsequent use of the upgraded biomass for partial coal replacement, and electrochemical treatment of a washcoat free wire mesh supported catalyst to reduce carbon monoxide emissions in combustion exhaust.

First, doping of secondary metals in M1/M2 catalysts for oxidative dehydrogenation of …