Engineering Commons^™

Vco Calibration Techniques And Design Of A 0.12-V Ultra-Low Supply Analog-To-Digital Converter, Shea Smith

Theses and Dissertations

Many analog-to-digital converters (ADC) quantize inputs using a voltage-controlled-oscillator (VCO). These VCO-based ADCs leverage time-domain processing to shape quantization noise and mismatch, which further increases their appeal. Despite these advantages, achieving good performance with a VCO-based ADC remains a significant challenge due to the nonlinear transfer characteristics of the voltage-to-frequency (V-F) conversion. VCO-based ADCs widely utilize coarse-fine readout to save power and hardware compared to counter-only converters. However, the timing mismatch due to the clock skew between the coarse and fine quantizers can lead to significant reconstruction errors. Chapter 2 proposes a digital calibration circuit to detect and correct coarse-fine …

Modeling Advancement In Spacefaring Through Deep Learning, Peng-Hung Tsai

Theses and Dissertations

Predicting advancement in space exploration technology allows space agencies and companies to strategically allocate resources, prioritize missions, and explore collaborations on complex projects. This foresight acts as a roadmap for future exploration, making the best use of valuable resources. The present study employs spacecraft lifetimes as an exemplar of technological progress and proposes a novel forecasting model based on Long Short-Term Memory (LSTM) networks. Existing research often suggests an increasing exponential relationship between technology performance and time (the generalized Moore's Law). However, applying this model directly to spacecraft lifetimes has a limitation. Spacecraft lifespans are unknown at launch, and recent …

Subspace Decomposition Of Linear Secrecy Codes, David Robert Joseph Hunn

Theses and Dissertations

We introduce a new method for the study of linear codes, termed subspace decomposition, which provides new insights into code structure and performance. Briefly, subspace decomposition comprises the evaluation of complex properties of a linear code by evaluating simple properties of its constituent subspaces. We find that this technique has application to a number of problems in coding theory. When applied to the problem of evaluating the performance of secrecy codes, subspace decomposition provides an efficient method for computing the equivocation of coset codes over the binary erasure wiretap channel. It is also especially efficient in computing the chi squared …

Reconfigurable Over-The-Air Chamber: Measuring Radio Frequency Device Performance, Benjamin T. Arnold

Theses and Dissertations

Over-the-air (OTA) testing is particularly useful in determining the performance of multi-antenna communication devices in real-world environments. Traditional OTA testing technologies include the reverberation chamber (RC) and the multi-probe anechoic chamber. More recently, the reconfigurable OTA chamber (ROTAC), which is a RC that has probes lining its chamber walls, has been proposed. These probes are either driven with a source, possibly combined with a channel emulator, or are terminated with a tunable impedance. Controlling the excitations and terminations on the probes can alter the fields within the chamber and thereby synthesize an antenna response at the device under test (DUT). …

Natural Language Processing For Automated Sysml Diagram Generation, Joshua Andre Ontiveros

Theses and Dissertations

This thesis explores the applications of natural language processing (NLP) techniques in model-based system engineering (MBSE) to help generate System Modeling Language (SysML) diagrams. MBSE is a method that aids in enhancing traditional engineering practices by modeling to help improve understanding and communication in systems development. SysML, one of the modeling languages for MBSE, helps represent a system's architecture, behavior, and information flow. Translating systems requirements and specifications into SysML models can be time-consuming and can lead to errors when created manually. Automating the creation of SysML diagrams from textual descriptions with the help of NLP techniques can aid in …

Synthesis Of Selenium Nanostructures: Rods, Wires, And Fibers By Pulsed Laser Ablation In Liquids, Atikur Rahman

Theses and Dissertations

Selenium is a semiconductor that has a bulk energy bandgap of 1.74 eV, is mainly used in sensors, rectifiers, and advanced photovoltaic solar cells. Selenium is very important for the energy applications and was declared as Energy Critical Element (ECE) by the American Physical Society (APS) and the Materials Research Society (MRS). The goal of this dissertation was to control the growth of selenium when being irradiated by a pulsed laser within a liquid environment. The method called “Pulsed Laser Ablation in Liquids” is a green synthesis technique that allows for ligand-free nanoparticles to be created. Laser repetition rates were …

Design Considerations For Self-Deploying Origami-Inspired Space Arrays, Kathryn Faith Varela

Theses and Dissertations

Origami engineering involves many steps, including selecting a pattern, accommodating for thickness, and choosing stabilization, damping, and deployment methods, the last of which is particularly important if the array is intended to self-deploy. Through metrics and case studies, this research strives to aid designers in creating origami-inspired deployable arrays. The approaches vary as each chapter focuses on a different aspect of origami engineering. By introducing a thickness accommodation technique and reducing complications with rigid-foldability (when applicable), this work shows how the geometrical structure can be modified to help the array stow and deploy. By providing quantitative and qualitative metrics for …

A Thermo-Mechanical Analysis Of The Well-Structure Integrity In Enhanced Geothermal Systems Using Numerical Simulation, John Alfred Ganal Acevedo

Theses and Dissertations

This thesis will investigate the well structure integrity of enhanced geothermal systems. Enhanced geothermal system is a type of renewable energy generation that utilizes heat from a rock reservoir deep within the Earth’s subsurface delivered by circulating working fluids through kilometers-long well structures. However, due to the surrounding environment and harsh operating conditions, the well structures are vulnerable to deterioration and cracking, which can lead to structural failure of wells and reduced energy efficiency. The study seeks to gain a better understanding of the vulnerability of the well structure. A finite element model of a well structure was developed, and …

The Development And Analysis Of Practical Decision Support Tool Implementations: Case Studies From Small Business To Large Government Enterprise, Alexis Andaverde

Theses and Dissertations

This thesis demonstrates the critical role of decision support tools (DSTs) in both small business and large government operations, enhancing decision-making, operational efficiency, and economic benefits. By implementing Excel-based systems for small businesses and discrete event modelling for large enterprises, this research highlights the importance of adaptable and scalable solutions across various sectors. According to the U.S. Small Business Association, small businesses with 500 or fewer employees make up 99.9% of all U.S. businesses. However, 65% of new businesses fail within the first ten years, according to the Bureau of Labor Statistics. This case study focuses on the used vehicle …

Validation, Optimization, And Experimentation Of Electro-Centrifugal Spinning, Carlos Alberto Delgado

Theses and Dissertations

The aim of this study is to understand the behavior of polymeric solutions, when exposed to both electric fields and centrifugal forces through the electro-centrifugal fiber creation method, observing both effects of various parameter variations on the resulting nanofibers. The elemental deposition on electrospun fibers through in-situ processes is studied and optimized. The morphology, crystallinity, thermal properties, and elemental composition of the nanofibers were characterized. The purpose of these nanofibers is for future applications such as energy harvesting, filtration, and biomedical applications.

Advancements In Aerial Vehicle Platforms: A Guide For Design, Validation, And Implementation Of 3d Printed Drones, Alan Salvador Urteaga

Theses and Dissertations

Additive manufacturing methods have revolutionized the way products are designed and developed through a product's entire design life cycle. This is in part correlated with the nature of additive manufacturing methods that differentiate them from traditional methods. Some of the benefits of additive manufacturing methods include customizability, rapid prototyping, the production of complex design geometry, and embedded assembly manufacturing. Unmanned aerial vehicles have been on the rise for various military, commercial, or personal applications. The focus of this study is to provide detailed instructions on how to engineer a viable drone design that is impact-resistant, modular, and customizable. This study …

Development Of The Structure And Control System Of A Stewart Platform Robot For Human Balance Recovery Interventions, Rhobenn R. Alvarez Zambrano

Theses and Dissertations

In this thesis, the process to design a Stewart platform parallel robot for balance recovery with given assembly constraints and mobility requirements is described. A Model Based Design (MBD) approach in MATLAB was used as a tool to model and optimize the design of the platform through quick and repeatable workspace and movements simulations. An algorithm based on Inverse Kinematics was used to find the most adequate Stewart platform configuration which yields a workspace that fulfills the design goals best. Solidworks was used as a 3D CAD Modeling tool to elaborate machining blueprints while ensuring that each piece fits accurately …

In Situ Shear Exfoliation Of Layered Materials And Fabrication Of Multifunctional Composites, Md Abdur Rahman Bin Abdus Salam

Theses and Dissertations

To harness the extraordinary properties of 2D nanomaterials across a range of applications, including but not limited to device fabrication (such as sensors and transistors), energy storage and conversion systems (like batteries and solar cells), as well as biomedical applications (such as drug delivery and tissue engineering), it is imperative to achieve proper synthesis to single-layer form from bulk material, ensuring defect-free synthesis. Recognizing the criticality of defect-free synthesis and high yield for nanocomposite production, our focus centered on developing a facile, contamination-free, single-step, in situ shear exfoliation process for bulk materials (such as graphene, hBN, coal) within elastomers, which …

Feature Extraction From Vibration Signature Acquired From Railroad Bearing Onboard Condition Monitoring Sensor Modules, Kevin Quaye

Theses and Dissertations

The University Transportation Center for Railway Safety (UTCRS) has designed an onboard monitoring system that tracks vibration waveforms over time, to obtain a direct and more accurate indicator of bearing health. The data collected by these sensors is used for vibrational analyses of the bearings. The speed of the bearing is a fundamental parameter needed to carry out the analysis. GPS data can be used to determine bearing speed if available; however, due to size, cost and power constraints GPS is typically not available at the sensor location. This means that analysis must be delayed until the data is uploaded …

Bridging Human Emotion And Autonomous Vehicle Control: Reinforcement Learning Enhancements In The Carla Simulator, Timothy Marion Jude Lyons

Theses and Dissertations

Autonomous vehicles are a key component for an evolution in transportation as they may lead to increased safety and productivity. As autonomous vehicles advance industries will look to further increase customer satisfaction through personalized experiences for autonomous vehicle passengers. Reinforcement learning may be the key to success for autonomous vehicles. The development of autonomous vehicles, utilizing reinforcement learning, which consider the emotions of the passenger, will be a breakthrough for the automotive industry. This thesis presents a unique approach to autonomous vehicles developed with reinforcement learning which consider the human emotions of the passenger. It is a stepping stone to …

Attachment Of 2d Nanomaterials Onto 1d Nanofibers For Separation And Sensing Applications, Elmmer A. Vera Alvarado

Theses and Dissertations

Advancing materials for water desalination and sensing is essential for tackling global issues related to clean water and efficient energy systems. This thesis explores the application of 2D nanomaterials, specifically graphene, integrated onto 1D poly(vinylidene fluoride) (PVDF) nanofibers to enhance their effectiveness in these areas. Utilizing innovative techniques such as Forcespinning® and plasma treatment, PVDF nanofibers were strengthened with graphene and conductive polymers like poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS). The research involved thorough assessments using direct contact membrane distillation (DCMD) systems, oil-water separation tests, and various mechanical and electromechanical evaluations. Heat-pressed membranes consistently delivered a flux of 0.33 kg/m²/hr and …

Application Of Electrical Impedance Tomography To Cementitious Composites, Hugo Zazueta

Theses and Dissertations

This thesis explores the feasibility of using Electrical Impedance Tomography (EIT) for detecting damage in cementitious composites. Cementitious composites, such as concrete and cement mortar, are insulating; any conductive properties arise from the moisture within their pores and capillary structures. The proposed concept herein is that formed internal damages in cementitious composites consequently alter their pore and capillary structure, which can then be detected through EIT imaging. To construct tomographic images, the Gaussian Newton (GN) reconstruction algorithm, enhanced with priors, was employed. The results were then compared across different reconstruction processes. Cylindrical cement pastes and cement mortar samples were prepared, …

Development Of An Efficient Multi-Objective Approach For Secure Live Virtual Machine Migration, Venkata Subramanian N

Theses and Dissertations

Cloud computing offers organizations flexibility and cost-efficiency through pay-asyou- go services, allowing them to scale resources according to their needs and reduce expenditures. Cloud as a Service (CaaS) offloads IT management complexities, while Cloud Data Center (CDC) provides infrastructure for on-demand, scalable, and flexible services over the Internet. Virtualization improves operational efficiency by providing simultaneous access to multiple virtual machines, while Live Virtual Machine Migration enhances agility, resilience, resource allocation, and fault tolerance.

However, achieving effective VMM requires forecasting cloud resource utilization, selecting the right target host, and ensuring security. Live VM migration is inevitable for optimizing CDC resource utilization. …

3d Printed Mounts For Liquid Microdroplet Resonators, Parker A. Awerkamp

Theses and Dissertations

Liquid microdroplet resonators provide an excellent tool for optical studies due to their innate smoothness and high quality factors, but they can be difficult to control. By using 3D printed mounts to support the droplets, we can obtain precise control over the droplet geometries and positions. We here present our work with oil, water, and ice microdroplets, as well as tools required to enable their study. We first present methods for creating 3D printed mounts for oil microdroplet resonators. The mounts enable precise positioning of the droplets relative to a tapered optical fiber. The oil microdroplet resonators exhibited quality factors …

Personalized Driving Using Inverse Reinforcement Learning, Rodrigo J. Gonzalez Salinas

Theses and Dissertations

This thesis introduces an autonomous driving controller designed to replicate individual driving behaviors based on a provided demonstration. The controller employs Inverse Reinforcement Learning (IRL) to formulate the reward function associated with the provided demonstration. IRL is implemented through a dual-feedback loop system. The inner loop utilizes Q-learning, a model-free reinforcement learning technique, to optimize the Hamilton-Jacobi-Bellman (HJB) equation and derive an appropriate control solution. The outer loop leverages this derived control solution to generate parameters for the reward function, which are subsequently integrated into the HJB equation. The ultimate control policy is deduced from the final reward function obtained …

The Role Of Furan Moieties On The Thermal Decomposition And Char Formation Of Intrinsically Fire-Resistant Epoxy Thermosets For Composites, Amy E. Honnig Bassett

Theses and Dissertations

Fire-retardant chemicals added to epoxy thermosets used as coatings, adhesives, and fiber-reinforced polymer composites (FRPCs) negatively impact performance and the environment. This dissertation takes a novel approach to mitigate the flammability of these systems by designing intrinsically fire-resistant epoxies via the incorporation of furan moieties. Glycidyl amines based on furfuryl amine and judiciously selected derivatives of furfuryl amine were synthesized to produce furan-based di-epoxies (FDEs) that were cured by anionic polymerization and with amine curing agents. The furan ring was found to impart additional reactivity for cross-linking and to induce char-forming reactions at higher temperatures. More importantly, the placement of …

Experimental Investigation On Mechanical Properties Of Pla Reinforced By Bamboo Fiber/Montmorillonite Clay Hybrid Composites And Analysis Of Machining Characteristics, Nirmal Kumar K

Theses and Dissertations

The study presents a comprehensive investigation into the development, characterization, and machining analysis of novel bio-based polymer hybrid composites comprising Polylactic acid (PLA), bamboo powders (BP), and montmorillonite clay particles (MMT). Initially, the hybrid composites were fabricated using a solvent-free stir casting process, optimizing the weight percentages of BP and MMT to enhance mechanical and thermal properties.

Mechanical tests, including tensile, flexural, and impact tests, along with thermal analysis using thermogravimetric analysis and differential scanning calorimetry, were conducted to evaluate the performance of the composites. In the subsequent phases, advanced machining techniques were employed to analyze the machining characteristics of …

Membrane Hinges For Deployable Systems, C. Mitchel Skinner

Theses and Dissertations

Origami-inspired and deployable technology has become increasingly common in a variety of applications including satellite and antenna designs for space applications. The drive to utilize ultra-thin materials in the design of these deployable space structures has led to the development of membrane hinges. Membrane hinges show promise as an effective surrogate fold because of their potential advantages including requiring minimal volume and mass, allowing for small bending radii, and functioning without lubricant. Two challenges associated with membrane hinges include reliability after repeated cyclic loading and predictability of a large deployable with radially-unconstrained membrane hinges. The research presented includes the cyclic …

The Planning Strategy For Electric Vehicle Charging Stations In The Road Transportation Network Synchronized With The Distribution Network, Muthukannan S

Theses and Dissertations

Electric vehicles (EVs) are recognized as a potentially effective solution to the environmental crisis and fuel deficit that modern metropolises are currently experiencing. Meanwhile, the expansion of EVs and their haphazard charging would negatively affect the road transportation network (RTN) as well as the electric distribution network (EDN). The proper infrastructure for the electric vehicle charging station (EVCS) will enhance the effective utilization of energy of both the networks.

This research work proposes a two-phase planning strategy for deploying Electric Vehicle Charging Stations (EVCS), considering both static and dynamic factors. The strategy uses a hybrid PSO-DS algorithm which is a …

Characterizing And Manipulating Intra-Die Performance Variation Of Fpgas And Its Application In Security, Hayden C. Cook

Theses and Dissertations

Field Programmable Gate Arrays (FPGAs) are reconfigurable, high-performing devices that are often used in critical applications. However, like all semiconductors, FPGAs experience transistor aging that can lower performance and lead to device failures. Additionally, device aging also has several security implications. Therefore, understanding the aging mechanisms behind transistor aging is necessary to ensure the reliability of FPGAs. However, current aging studies either rely on simulation alone or are unable to isolate aging effects on specific elements within the FPGA. This dissertation uses the reconfigurability of FPGAs to develop novel aging techniques that allow for the targeted aging of specific areas …

Investigating The Fatigue Life Of Asymmetric And Novel Helical Gear Drives, Rajesh S

Theses and Dissertations

The present research work investigates the contact and bending fatigue life of asymmetric helical gear and novel helical gear based on the finite element analysis. In the first phase, the contact and bending fatigue life of the asymmetric helical gear drives is estimated based on the strain life approach.

Further, a parametric study is carried out to investigate the influence of important helical gear parameters such as module, pressure angle, helix angle, gear ratio, teeth number and face width on contact and bending fatigue life of asymmetric helical gear drives. It is noted that the asymmetric helical gear shows a …

Investigation Of Various Mimo Antenna For 5g Mobile Phone Applications, Rajesh Kumar D

Theses and Dissertations

The rapid progress of wireless communication systems has been driven by the persistent demand for higher data rates, improved connectivity, and seamless user experiences. The introduction of fifth-generation (5G) wireless technology introduces fresh challenges and possibilities within the domain of antenna design, particularly concerning Multiple-Input Multiple-Output (MIMO) systems operating in the sub-6 GHz frequency range. This thesis conducts a comprehensive exploration and conceptualization of MIMO antennas expressly crafted for smooth integration into mobile phones, with a particular emphasis on addressing the distinctive requisites of sub-6 GHz 5G communication.

The proposed antenna designs effectively harnesses the advantages inherent in multiple-input multiple-output …

Drop Dynamics And Heat Transfer During Dropwise Condensation On Superhydrophobic Surfaces, Shaur Humayun

Theses and Dissertations

As we seek to address the escalating demand for energy and water, superhydrophobic surfaces have gained the attention of researchers due to their potential to boost condensation heat transfer rates and improve efficiency across various applications. One way to significantly improve dropwise condensation heat transfer rate is to improve drop mobility. Water-repelling properties of superhydrophobic surfaces can help in reducing the size of condensed drops as they depart the surface, thus increasing drop refresh rates by increasing drop mobility. Accurate models of retention forces between drops and superhydrophobic surfaces are needed for predicting drop dynamics including drop mobility. Once drop …

Design And Implementation Of Truly Random Number Generation Using Memristors For In-Memory Computing, Nick Felker

Theses and Dissertations

This paper proposes a new security module based on non-volatile memory. The module uses a memristor-based true random number generator to generate random numbers which can be used for cryptography. The module is implemented in software using a modified RISC-V instruction set architecture. The paper evaluates the performance of the module using the RISC-V simulator Gem5. The results show that the module can generate random numbers at a rate of 63 microseconds per number, which is faster than the standard C library’s random number generator. The module can also be used to scramble strings of characters and generate hashes of …

Reconfigurable Metasurface For 5g & Beyond Wireless Communication, Monisha S

Theses and Dissertations

The potential new applications and increasing demands of future 5th generation (5G) and beyond wireless communication indicate a promising future for mobile communications. However, the transmission medium has traditionally been seen as an unpredictable factor between the sender and receiver. As we enter the digital era of wireless communications, signal quality is deteriorating due to environmental interferences.

With the continuous advancement of technology, there is an increasing need for advanced solutions that can handle complex applications such as haptic communications, the Internet of Things for smart cities, automation, and manufacturing. One technology that has received much attention is the reconfigurable …