Engineering Commons^™

Sub-1k Cold Electron Transport At Room Temperature, Anthony Martinez

Material Science and Engineering Dissertations - Archive

Thermally excited electrons at the high-energy tail of the Fermi-Dirac distribution impose fundamental limitations on the performance of solid-state electronic and spintronic devices. For example, the thermally excited electrons obscure the Coulomb blockade essential for single-electron transport. The hot electrons can also overcome the energy barrier of Metal-Oxide-Semiconductor Field-Effect transistors (MOSFETs), causing unwanted leakage currents that lead to excessive power consumption in the integrated circuits. This study investigates an approach in which quantum states are used to manipulate electron tunneling, blocking the transport of thermally excited hot electrons, thereby enabling cold-electron transport at room temperature. Here two heterogeneous quantum wells …

A Low-Noise, Low-Power Cmos Readout Ic For Amperometric Electrochemical Sensing System, Manu Chilukuri

Electrical Engineering Dissertations - Archive

Electrochemical sensing systems have become essential tools in numerous fields due to their exceptional sensitivity, selectivity, and versatility. They play a critical role in modern research, industry, environmental monitoring, and healthcare applications. In environmental monitoring, these systems are utilized to detect pollutants, heavy metals, and toxic gases, enabling real-time monitoring and ensuring environmental protection. In the biomedical sector, electrochemical sensing systems are vital for diagnosing diseases, monitoring biomarkers, and transforming healthcare practices.

Affordable wearable electrochemical sensing devices are crucial for making healthcare more accessible and improving public health outcomes. These devices allow for continuous monitoring of physiological parameters, supporting early …

Unsupervised Machine Learning In Wireless Sensor Measurements And Hyperspectral Imaging, Abrar U. Alam

Electrical Engineering Dissertations - Archive

The increasing demand for real-time analysis of sensor data in dynamic environments necessitates innovative approaches to data clustering. This work introduces a novel Online Kernel Clustering (OKC) framework that efficiently determines time-varying clustering configurations without requiring training data. The proposed method employs sparse kernel factorization, guided by a time-dependent metric to quantify the closeness of kernel similarity matrices to a block diagonal structure. By processing data sequentially, the OKC framework is tailored for non-stationary settings. The optimization process integrates block coordinate descent, difference-of-convex functions minimization, and projected sub-gradient descent to iteratively update kernel covariance matrices and cluster memberships online. Numerical …

A Path To Commissioning Of Direct-To-Chip Liquid Cooling For Hyperscale Data Centers Using Experimental And Cfd Techniques, Himanshu Girishchandra Modi

Mechanical and Aerospace Engineering Dissertations - Archive

The escalating demand for computing power in hyperscale data centers necessitates innovative cooling solutions to enhance energy efficiency and ensure sustainable operations. Direct-to-chip liquid cooling has emerged as a promising alternative to traditional air-cooling methods, offering improved thermal management and reduced energy consumption. This dissertation explores a comprehensive approach to commissioning direct-to-chip liquid cooling systems in hyperscale data centers by integrating experimental analyses and Computational Fluid Dynamics (CFD) techniques. The study begins by examining design modifications for air-cooled servers and later analyzes the impact of different parameters for a hybrid-cooled server. It explores the fundamental principles of direct-to-chip liquid cooling …

Kissing Bond Assessment In Adhesive Bonded Carbon Fiber Reinforced Composites Using Dielectric Spectroscopy, Minhazur Rahman

Mechanical and Aerospace Engineering Dissertations - Archive

The widespread use of fiber-reinforced composites in industries such as space, aviation, automobiles, and construction necessitates the formation of robust composite joints between critical structural components. Although adhesive-bonded joints are superior with improved load distribution and reduced weight, they are often overlooked in favor of bolted joints and mechanical fasteners due to the lack of reliable Non-Destructive Evaluation (NDE) techniques for adhesive-bonded composites. The anisotropic nature of the substrate and the intricate interfacial interactions between the adherend and adhesive material present significant challenges for conventional NDE methods. Moreover, weak adhesive bonds can result from uncontrolled manufacturing parameters, such as accidental …

Two-Phase Flow Simulations With Plic-Vof Method And Dynamic Mesh Refinement, Vimalan Adaikalanathan

Mechanical and Aerospace Engineering Dissertations - Archive

Two-phase flows are critical in a variety of engineering applications that span multiple length scales. These applications encompass macroscopic phenomena, such as dam breakage and wave-structure interactions, as well as microscopic events, including droplet impacts and boiling, and mixed-scale issues like spray dynamics. Accurate representation of evolving interfaces is essential for numerical simulations of these problems, and the Volume of Fluid (VOF) method combined with the Piecewise Linear Interface Calculation (PLIC) approach is employed to fulfill this requirement. To tackle the computational challenges associated with high-resolution meshes in deforming two-phase flows, Adaptive Mesh Refinement (AMR) is utilized to enhance mesh …

Design And Experimentation Of Novel Human Head Surrogate Models For Sensing Traumatic Brain Injury, Arthur T. Koster

Mechanical and Aerospace Engineering Dissertations - Archive

Brain injury is a significant source of mortality in the US and has been an important area of research over the past century. The need to understand injury thresholds and pathology coupled with the difficulty of measuring relevant injury mechanisms in a living subject logically gives rise to the idea that researchers need to create head models for use in simulation and experimentation. This study focuses on understanding the effects of material properties, size, and shape on the dynamic response of a head model so that head models used in simulations and experiments can more accurately represent the real human …

Experimental Investigations And Optimization Of 3d Printed Cellular Structures For Protection Against Traumatic Brain Injury, Aaron R. Jackson

Mechanical and Aerospace Engineering Dissertations - Archive

Traumatic Brain Injury (TBI) disrupts brain function due to head impacts, blast exposures, and ballistic penetrations. It is a significant cause of mental health issues and disability, particularly among military personnel. Historically, combat helmets were designed primarily to protect against fragments. However, recent data highlights the need for helmets that also protect against blast and blunt impacts. Effective TBI prevention requires helmets that address various energy threats while remaining lightweight. A critical metric in this effort is head acceleration, which is closely linked to injury across different scales of brain damage.

Four lattice structures were 3D printed using Digital ABS …

Synthesis Of Ni-Based Intermetallics By Electrolytic Plasma Processing Of Ti And Ti-Based Alloys, Chuzhong Zhang

Material Science and Engineering Dissertations - Archive

EPP is an innovative surface modification technique that enables the deposition of metal ions from the electrolyte and their integration with substrate atoms to form intermetallic compound surface layers. EPP offers advantages such as high deposition rates, environmental cleanliness, and operational simplicity. In this study, Ni-Ti intermetallic layers were successfully synthesized on a Ti-6Al-4V substrate using EPP. The properties of the resulting Ni-Ti intermetallic layers were characterized using SEM, EDS, XRD, TEM, nanoindentation, and tribology tests.

This work aims to understand the fabrication mechanism and investigate the effects of various processing parameters on the EPP process. Key factors such as …

Introduce Ultrasound Fabry-Pérot Resonator For Attenuation Characterization And Sensitization Detection Of Aluminum-Magnesium Alloys, Songwei Wang

Mechanical and Aerospace Engineering Dissertations - Archive

The Ultrasound Fabry-Pérot Resonator (UFPR) is introduced as a novel technique for non-destructive evaluation and material characterization. By adapting optical Fabry-Pérot Resonator principles to ultrasonic systems, UFPR inherits advantages such as enhanced sensitivity, reduced uncertainty, and the capabilities of frequency-dependent analysis and fringe spectral analysis. This study focuses on UFPR’s application to ultrasonic attenuation characterization and sensitization detection in aluminum-magnesium alloys, which are critical for understanding microstructural changes and improving material performance.

The research was conducted in three systematic steps. First, time-frequency analysis was utilized to examine frequency-dependent attenuation behavior, establishing a foundation for ultrasonic attenuation characterization. Second, longitudinal UFPR …

Mathematical Modeling Of Heat And Mass Transfer In Multilayer Systems, Girish Krishnan

Mechanical and Aerospace Engineering Dissertations - Archive

Multilayer systems are commonly found in a number of engineering devices like Li-ion cells and vertically integrated semiconductor devices. Li-ion cells are widely used for various engineering applications, but they come with a drawback in the form of thermal runaway, and thermal abuse is one of the scenarios that leads to thermal runaway. On the other hand, heterogenous integration in chip and package level architectures is being implemented to keep up with Moore’s law. Modeling of heat and mass transfer in these systems is a topic of interest to improve performance and reliability.

The first segment of this dissertation will …

Development Of A 3d Printed Optimization-Driven Aeroelastically Scaled Wind Tunnel Model For High Aspect Ratio Flying Wings, Mikaela K. Leevy

Mechanical and Aerospace Engineering Theses - Archive

Design optimization coupled with 3D printing and parametric CAD offers a unique approach to investigating flutter phenomena by creating low-cost iterative aeroelastic wind tunnel models. Recently, there is an interest in studying flutter phenomena at low air speeds in flying wing configurations. The X-56 experimental flying wing was designed to investigate flutter phenomena and flutter suppression, which makes the X-56 a logical choice for the full-scale model. The goal of this work is to optimize, physically print, and geometrically characterize a scaled aeroelastic wind tunnel model. The 18% reduced scale X-56 model was optimized by matching the mode shapes to …

Optimizing Multi-Agent Network For Target Localization Through Mutual Information Maximization, Bibek Adhikari

Mechanical and Aerospace Engineering Theses - Archive

A multi-agent network is a system comprising multiple interacting agents that coexist collaboratively within a networked, autonomous environment. The thesis addresses the target localization problem using a multi-rover network, described as autonomous agents, using an information-theoretic distributed control framework. The objective of the mission, through the integration of the particle filter representation of the posterior probability distribution of the target state and the observable, is to compute control input to arrange agents’ locations, maximizing the mutual information between the target’s position and sensor measurements. Consequently, the method leads to future observation which minimizes the future uncertainty of the target state. …

Parametric Analysis Of A Dynamic And Static Model For Low Velocity Impact Of Specially Orthotropic Laminates, Juan Daniel Ruiz

Mechanical and Aerospace Engineering Theses - Archive

The high specific strength and specific stiffness of composite materials makes them highly desirable for structural applications, but their laminated nature makes them susceptible to impact damage. Even low velocity impacts (LVI), generally, result in barely visible impact damage (BVID) and delamination, which can go unnoticed and grow during service, eventually leading to catastrophic failure. Due to this, the study of impact resistance and damage tolerance is typically studied through LVI followed by compression after impact (CAI) experiments. However, conducting LVI experiments are time consuming and expensive, as they require specialized equipment and extensive pre-test preparations.

In this study, the …

Cooperative Navigation In Gps-Denied Environments Using Visual Simultaneous Localization And Mapping (Slam), Rakesh Yadav

Mechanical and Aerospace Engineering Theses - Archive

In this thesis, an application of RTAB-Map’s visual SLAM (Simultaneous Localization and Mapping) is used to explore autonomous cooperative navigation in GPS-denied environment using a rover and a quadrotor. The primary objective is to enhance cooperative navigation by allowing the rover and the drone to guide each other using the maps constructed or generated by them. The map is generated using the RTAB-Map SLAM technique using stereo camera only. The thesis addresses three major issues: quality of map created by UAV and UGV, the visual odometry drift, and the robustness of the cooperative framework in the static and dynamic environment. …

Study Of A Multi-Agent Containment Problem Under Communication Constraints And Defense From Malicious Agents, Braulio Mora

Mechanical and Aerospace Engineering Theses - Archive

This thesis investigates a multi-agent containment problem where a fast evader, moving at a constant speed and heading, attempts to escape a circular containment region. A team of slow pursuers possess a nonzero capture radius and seek to capture the evader before escape. The research addresses two primary scenarios: one involving the team of pursuers, with no communication network, being constrained to the edge of the containment region, and the second involving a team of pursuers, with a communication network, not being constrained to the edge of the containment region. Both scenarios study the influence of malicious agents in the …

Nonlinear Guidance And Control Of Unmanned Aerial Manipulators For Delivering A Payload On A Moving Platform, Ravi Gyawali

Mechanical and Aerospace Engineering Theses - Archive

Unmanned Aerial manipulators (UAMs) are a class of Unmanned Aerial Vehicles (UAVs) equipped with a manipulator. By combining the aerial mobility of a UAV with a manipulator's dexterity, these hybrid systems can perform a wide range of complex tasks while reducing risks and costs. As a result, they are increasingly being utilized for military, industrial, and agricultural applications.

The thesis presents a novel approach for a multi-UAM system to collaboratively deliver a payload on a stationary or maneuvering platform. A sliding-mode-based guidance law, sourced from existing literature, is integrated with a combined control technique for the UAVs and their respective …

Image-Based Thermal And Mechanical Analysis Of Polymers, Yukti Shinglot

Mechanical and Aerospace Engineering Theses - Archive

In recent years, application of polymers have rapidly expanded across industries due to their versatility, cost-effectiveness, and adaptability to diverse manufacturing techniques, including 3D printing. Innovations in PolyJet technology enable the creation of complex geometries with tailored color combinations, transparency, and flexibility, broadening applications in medical, aerospace, and automotive sectors. Advances in processing viscoelastic rubbers like PDMS (Polydimethylsiloxane) have further enhanced its mechanical properties, expanding its use in biomedical devices and electronic components. However, polymers are susceptible to complex deformation and failure under thermal and mechanical stresses, which can impact their performance and safety. This research examines the thermal behavior …

Electophorectic Deposition For Novel Nanodecorated Electrodes Towards Thermally Charging Supercapacitor (Tcsc), Ashish Thakur

Mechanical and Aerospace Engineering Theses - Archive

Thermally Self-Charging Supercapacitors (TSCS) are a promising new technology that can harvest waste heat to produce electrical energy. The Soret effect is exploited wherein ion separation due a temperature gradient leads to a potential difference. Here, we use electrophoretic deposition (EPD), a room-temperature, scalable, universal technique, to obtain CNT decorated electrodes for fabrication of such TSCS devices with ionic liquid electrolyte. We further show that precise control over deposition parameters can be used for optimization of TSCS performance metrics. TSCS devices were tested by several characterization standards, indicating the superior performance of nanodecorated electrodes obtained by EPD.

Thermal Damage And Mechanical Failure Analysis Of Polymers, Tina Ko

Mechanical and Aerospace Engineering Theses - Archive

As the demand for more intricate and precise components increases, polymers continue to stand out for their flexibility, durability, and adaptability across numerous applications. From aerospace to biomedical engineering industries, polymers are valued for their versatility and customizability, enabling the creation of complex geometries or achieving specific material properties. Since polymers are widely used, analyzing their thermal and mechanical properties is essential to understand their behavior under high-energy exposure or defects. Two types of polymers were analyzed: Polydimethylsiloxane (PDMS) and 3D-printed digital materials. This thesis investigates the mechanical and thermal response of polymers through two distinct studies. The first part …

Dynamics Of Separated Flows In Diffusers With Vortex Generators, Sandeep Eldho James

Mechanical and Aerospace Engineering Dissertations - Archive

Flow through curved diffusers is complicated due to the possibility of flow separation and secondary flows. Vortex generators (VGs) are a class of passive flow separation control devices used to improve the flow quality in curved diffusers by suppressing flow separation. However, the literature review demands an in-depth investigation on the physical mechanisms related to flow separation control. Thus, this study aims to improve the understanding of the underlying flow physics associated with VG-induced flow separation control in confined flows. The chosen geometry for this study is a well-documented asymmetric diffuser which exhibits a mild flow separation.

The theoretical formulation …

Generalizable Fugitive Carrier Method For 3d Printing Of Hydrogels, Hakan Arslan

Mechanical and Aerospace Engineering Dissertations - Archive

Hydrogels, with physical characteristics resembling biological soft tissues, hold great potential for bioinspired and biomedical applications. However, using them in additive manufacturing systems has challenges because of their poor mechanical and rheological properties. In response to these challenges, we introduce a fugitive carrier method, a novel and generalizable approach for materials incompatible with pneumatic-based extrusion three-dimensional (3D) printers. Our developed fugitive carrier method allows the 3D printing of a broad spectrum of hydrogel precursors with low viscosity while retaining their inherent properties. This technique has been successfully demonstrated by creating biomimetic structures with anisotropic and programmable systems utilizing temperature-sensitive hydrogel …

Quantitative Modeling Of Micro Discharge And Oxide Growth In Plasma Electrolytic Oxidation Of Titanium, Kingsley I. Ochiabuto

Material Science and Engineering Dissertations - Archive

Plasma electrolytic oxidation (PEO) has been extensively applied in the past to improve the tribological properties of titanium and its alloys allowing their widespread use in industrial applications. However, the complete PEO mechanism of action remains unclear. While there are several mathematical models providing useful insights into the PEO process, they do not fully incorporate the effect of applied potential on the outcomes of PEO. In this work, we develop an experimentally informed computational model by expanding on the dielectric breakdown model. We incorporate experimental data to extract key parameters, exploring the iterative dependency of the oxide thickness and ionic …

Machine Learning-Based Methodology For Multi-Objective And Multi-Design Variable Optimization Of Finned Heat Sinks And Evaluation Of Electrochemical Additive Manufactured Heat Sink Designs For Single-Phase Immersion Cooling, Joseph F. Herring Ii

Mechanical and Aerospace Engineering Dissertations - Archive

Traditional air-cooling along with corresponding heat sinks are beginning to reach performance limits, requiring lower air-supply temperatures and higher air-supply flowrates, in order to meet the rising thermal management requirements of high power-density electronics. A switch from air-cooling to single-phase immersion cooling provides significant thermal performance improvement and reliability benefits. When hardware which is designed for air cooling is implemented within a single-phase immersion cooling regime, optimization of the heat sinks provides additional thermal performance improvements. This work investigates performance of a machine learning (ML) approach to building a predictive model of the multi objective and multi-design variable optimization of …

Human System Composite Performance Measures: General Systems Performance Theory Insights, Lawrence Disalvi

Bioengineering Dissertations - Archive

Composite Performance Measures (CPMs) of human performance are widely employed in applications that range from mundane to life-changing, yet they are frequently presented without explanation or reference to theoretical underpinnings. The conceptual soundness of a widely used CPM approach, based on additive combination of constituent components, has been called into question by Kondraske. He argues the relevance of General Systems Performance Theory (GSPT) and performance capacity envelope concepts when applied to multidimensional CPM measures.

To obtain evidence-based answers to assertions regarding CPM types and rationale employed in medical and non-medical contexts, a Systematic Descriptive Review was conducted. Separately, the GSPT-based …

Algorithm Development For Analysis Of Optical Time-Series Data Generated By Biomodal Optical-Electrical Nanopore Sensor, Yu-Shiuan Huang

Bioengineering Theses - Archive

Nanopore biosensors have played an essential role in the scientific investigation of DNA, RNA, proteins, and other bio-analytes. Traditional nanopore biosensors detect variations in electrical current conductance caused by the analyte blocking the current passing transiently through a nano-sized aperture, i.e., the nanopore. This electrical data provides information about the amount of current blockage when the analyte is inside the nanopore and the time it takes for analytes to travel through the nanopore (translocation time). The translocation time of analytes in standard nanopore measurements is typically very short, usually tens of microseconds, limiting the accuracy of measuring the analytes’ characteristics. …

Computational And Experimental Analysis Of Silica Nanoparticles Under Dc And Ac Electric Fields Using A Self-Induced Back Action Actuated Nanopore Electrophoresis (Sane) Sensor, Homayoun Asadzadeh, Scott Renkes, George Alexandrakis, Minjun Kim, Scott Turpin

Bioengineering Dissertations - Archive

In this dissertation I have studied a novel single-molecule nanosensor that integrates a Solid-State Nanopore (SSNP), milled in silicon nitride with a Double Nanohole (DNH) nanoaperture, milled in gold. This device leverages Self-Induced Back-Action (SIBA) for optical trapping with ssNP electrical sensing and is called the SIBA-Actuated Nanopore Electrophoresis (SANE) sensor. My lab has previously shown that simultaneous acquisition of bimodal optical and direct current (DC) electrical signatures enables more detailed characterization of nanoscopic analytes compared to using electrical data alone, which are typically collected by ssNP sensors. In this work I have first studied by COMSOL Multiphysics simulations the …

Spray-On Sensor Formulations That Enable Detection Of Physical And Chemical Stimuli, Priyanka Shiveshwarkar

Bioengineering Dissertations - Archive

Polydiacetylene based materials have been used for a variety of liquid phase sensing applications. There remains a need for low cost, easy-to-read gas phase sensors for continuous monitoring of physiological parameters and environmental hazards at work or at home. Such sensors could have applications in everyday life, for example as point-of-care or at home testing devices to enable early detection of disease to reduce healthcare costs. Making accessible and non-invasive technologies for monitoring of health and health risks provides individuals with the ability to be proactive in regard to their health and safety. In other examples, environmental monitoring systems could …

Development Of Anti-Microbial Nanocoatings On Metallic Surfaces To Prevent Infections, Luis Fernando Soto Garcia

Bioengineering Dissertations - Archive

Healthcare-associated infections have a prevalence of about 7% in the United States and up to 50% in some developing nations. They not only present a constant risk for inpatients and healthcare workers but are also a serious challenge to human health services worldwide. These infections can be transmitted via contaminated non-critical surfaces like doorknobs and bedrails, which are routinely cleaned with low-level disinfectants approved by the U.S. Environmental Protection Agency. However, this strategy has limited efficacy since recontamination occurs, resulting in these surfaces again becoming vectors of infection. In this work, we addressed this issue by developing a self-disinfecting nanocomposite …

Net-Zero Home Race: Gamification For Learning Energy Consumption Merit, Terry E. Payne

Civil Engineering Theses - Archive

Buildings have contributed significantly to carbon emissions over the past decades, amplified by rapid construction growth. To address this, sustainable concepts like energy efficiency and financial planning for home retrofitting have become essential in promoting environmentally conscious practices. NZHR was created as a gamified experience to help bridge the gap between education and motivational enjoyment. Testing the game demonstrated participants' ability to learn and understand the importance of strategic thinking with home retrofit upgrades. Gamification principles such as the Octalysis and Bartle test were incorporated into the design process to construct a well-rounded game that provides intrinsic and extrinsic principles. …