Engineering Commons^™

Energy Dissipation In A Sand Damper Under Cyclic Loading, Ehab Sabi

Civil and Environmental Engineering Theses and Dissertations

Various seismic and wind engineering designs and retrofit strategies have been in development to meet structures' proper and safe operation during earthquake and wind excitation. One such method is the addition of fluid and particle dampers, such as sand dampers, in an effort to reduce excessive and dangerous displacements of structures. The present study implements the discrete element method (DEM) to assess the performance of a pressurized sand damper (PSD) and characterize the dissipated energy under cyclic loading. The idea of a PSD is to exploit the increase in shearing resistance of sand under external pressure and the associated ability …

Leveraging Crowdsourced Navigation Data In Roadway Pluvial Flash Flood Prediction, Arefeh Safaei-Moghadam

Civil and Environmental Engineering Theses and Dissertations

This dissertation develops and tests a new data-driven framework for short-term roadway pluvial flash flood (PFF) risk estimation at the scale of road segments using crowdsourced navigation data and a simplified physics-based PFF model. Pluvial flash flooding (PFF) is defined as localized floods caused by an overwhelmed natural or engineered drainage system. This study develops a data curation and computational framework for data collection, preprocessing, and modeling to estimate the risk of PFF at road-segment scales. A hybrid approach is also developed that couples a statistical model and a simplified physics-based simulation model in a machine learning (ML) model to …

Experimental And Numerical Studies On Laser Hot Wire Cladding By A High-Power Direct Diode Laser, Mingpu Yao

Mechanical Engineering Research Theses and Dissertations

Laser hot wire cladding is an advanced surface modification technology. It has been extensively growing during the last decades due to its high deposition rate, good metallurgical bonding between the substrate and clad layer, low dilution ratio, and small heat-affected zone. There are many kinds of lasers widely used in the laser cladding process. The high-power direct diode laser is widely welcomed because of its high energy efficiency, high electro-optic conversion efficiency, low cost, and high reliability. A rectangular-shaped direct diode laser beam combined with hot wire feeding can achieve a lower dilution depth with a uniform fusion line compared …

Novel Locomotion Methods In Magnetic Actuation And Pipe Inspection, Adam Cox

Mechanical Engineering Research Theses and Dissertations

There is much room for improvement in tube network inspections of jet aircraft. Often, these inspections are incomplete and inconsistent. In this paper, we develop a Modular Robotic Inspection System (MoRIS) for jet aircraft tube networks and a corresponding kinematic model. MoRIS consists of a Base Station for user control and communication, and robotic Vertebrae for accessing and inspecting the network. The presented and tested design of MoRIS can travel up to 9 feet in a tube network. The Vertebrae can navigate in all orientations, including smooth vertical tubes. The design is optimized for nominal 1.5" outside diameter tubes. We …

Orbital Angular Momentum Orthogonality-Based Crosstalk Reduction: Theory And Experiment, Unaiza Tariq

Electrical Engineering Theses and Dissertations

Full duplex communication systems allow a single channel to be used for simultaneous two-way communication, increasing spectral efficiency. However, full duplex communication systems suffer from the issue of self-interference between local transmitter and receiver antennas. Analog subtraction and signal processing methods have previously been used to reduce this problem. This dissertation proposes the use of waves carrying orbital angular momentum (OAM) to mitigate the problem of self-interference by offering a means of additional isolation between local antennas.

Orbital angular momentum has been widely studied both in the photonics and radio domain. The theoretically infinite orthogonal states of an OAM signal …

Distribution Network Operation With Solar Photovoltaic And Energy Storage Technology, Mohammad Ramin Feizi

Electrical Engineering Theses and Dissertations

Among distributed energy resources, solar photovoltaic (PV) generation has the largest penetration in the distribution networks. Serving electric vehicles (EV) with renewable resource generation would further reduce the carbon footprint of the energy supply chain for electric vehicles. However, the integration of solar PV and EVs in the unbalanced distribution network introduces several challenges including voltage fluctuations, voltage imbalances, reverse power flow, and protection devices’ malfunctions. The uncertainties associated with solar PV integration and electric vehicles operation require significant effort to develop accurate optimization methodologies in the unbalanced distribution systems operation. In this thesis, in order to cope with the …

Development And Application Of A Design Flow For Photonic Integrated Circuits, Ifeanyi Achu

Electrical Engineering Theses and Dissertations

Silicon photonics allows for the fabrication of many optical elements on a single photonic integrated circuit (PIC). By taking advantage of the established foundry technology used in the CMOS and silicon’s high refractive index, high feature density manufacturing can be achieved in mass quantities. In CMOS fabrication, from conception of an electronic circuit to testing, the process of designing an electronic circuit is dictated by a design flow which has been developed over the course of decades. This flow includes circuit level design and simulation, layout of the circuit, layout and verification of the chip, fabrication, packaging, and testing. Given …

An Investigation Of The Role Of System Effectiveness In The Acquisition And Sustainment Of U.S. Defense Systems: 1958 To 2022, John Green

Operations Research and Engineering Management Theses and Dissertations

This dissertation investigates the role of the system effectiveness methodology in acquiring and sustaining U.S. military weapons systems from 1958 to 2021. The period of interest has seen numerous changes in both the acquisition process and the application of system effectiveness to acquisition and sustainment. Several of the changes were disruptive, including shifting acquisition and sustainment to a commercial paradigm and completely overhauling the approach to acquiring new systems. The method of inquiry integrated three qualitative methods–structured literature review, grounded theory analysis, and historiography–into an innovative approach for investigating the changes to system effectiveness. The database for the investigation was …

Void-Semiconductor Gaas Photonic Crystal Surface-Emitting Lasers By Epitaxial Regrowth And Single-Epitaxy Methods, Kevin James Reilly

Nanoscience and Microsystems ETDs

Monolithic semiconductor lasers including edge-emitting lasers (EELs) and vertical-cavity surface-emitting lasers (VCSELs) fail to realize simultaneous achievement of both high-power high-quality beams due to intrinsic limitations of their resonant cavity. Photonic crystal surface emitting lasers (PCSELs) address these structural limitations through employment of a two-dimensional photonic crystal (PC) cavity that creates feedback at a single wavelength for laterally scalable devices. This function of the PC allows PCSELs to power scale with area while maintaining single-mode emission required for diffraction-limited beams. In this way, PCSELs fulfill an industry demand for high-power high-quality lasing from a single chip.

Early PCSELs were fabricated …

On The Effects Of Geometrical And Fluid Conditions On Thermal-Hydraulics Of Miniature Heat Sinks, Mahyar Pourghasemi

Mechanical Engineering ETDs

During the past three years, miniature heat sinks have been integrated into the cooling loop of devices such as MW-class gyrotron resonators and high-power laser arrays. These applications involve high cooling rates in the range of 20-25 MW/m². Liquid metals such as Na and NaK offer very high thermal conductivity in the range of 16-79 W/mK, while their dynamic viscosities are only slightly higher than water viscosity. They can also be used in applications with operating temperatures varying from 25 ^oC to as high as 800 ^oC due to their very high boiling points. Several research …

Cyber-Secure Distributed Control Of Microgrids With Improved Communication And Control Protocols, Jee Won Choi

Mechanical Engineering ETDs

This dissertation proposes a cyber-secure distributed control of microgrids with improved communication and control protocols. The finite-time event-triggered control protocol for islanded AC and DC secondary control is introduced. For AC microgrids, the proposed strategy can effectively perform frequency restoration and voltage regulations while sharing the active and reactive power among the distributed generators (DGs) based on their power ratings. For DC microgrids, the proposed control protocol can provide accurate current sharing and critical bus voltage regulation. The finite-time control enables a system to reach a consensus in a finite period of time enhanced from asymptotic convergence. The event-triggered communication …

Formation And Interrogation Of A Modeling Excel Database For Sorbent Preconcentrate With Gc/Ms, Lisa Caravello

Chemical and Biological Engineering ETDs

Volatile organic compounds (VOCs) are of great interest and the subject of much research, as they can be used in various applications. Preconcentrating this class of analytes is necessary as they can be elusive with simple sampling techniques. VOCs are often captured using sorbents in thermal desorption tubes as preconcentrates prior to analysis, commonly gas chromatography mass spectroscopy (GCMS). There are gaps in knowledge in behavior of materials used as sorbents i.e., if they will retain an analyte of interest appropriately. In this research I seek to eliminate speculation and unknown variables of analyte and sorbent combinations by creating a …

Reinforcement Learning-Based Demand Response Management In Smart Grid Systems With Prosumers, Jenilee Jao

Electrical and Computer Engineering ETDs

In this thesis, we introduce a reinforcement learning-based price-driven Demand Response Management (DRM) mechanism in smart grid systems consisting of prosumers. Our proposed approach accounts for the prosumers behavioral characteristics and models the emerging interactions among all the involved actors in the smart grid system, i.e., prosumers, Energy Management System (EMS) and utility companies. In particular, an off-policy reinforcement learning is introduced enabling the EMS to determine the optimal price that should be announced to the prosumers on an hourly-basis towards minimizing the overall systems cost. In this process, the utility companies hourly-based wholesale price and the prosumers energy generation …

Journal Of Pre-College Engineering Education Research (J-Peer) Annual Report From January 1, 2021, To December 31, 2021, Senay Purzer, Urvi Gupta

Journal of Pre-College Engineering Education Research (J-PEER)

This annual report includes the Journal of Pre-College Engineering Education Research’s readership metrics and statistics, authorship metrics and trends, and our reflections on 2021. In the last year, the Journal of Pre-College Engineering Education Research started to publish special issues and the editorial team has been working to transform pre-college engineering education.

Computational Symmetric Grain Boundary Energy Of Thorium Dioxide, Brendan J. Carroll

Honors College Theses

With fossil fuels being depleted at a faster rate than ever, there has been an effort to convert fossil fuel energy to different forms of green energy. One of these forms is nuclear power, and while nuclear power itself is not new, new fuel sources for different types of reactors are being developed. This study aims to do computational experiments on Thorium Dioxide (a potential new nuclear fuel source) to look for the lowest grain boundary energy and what the effect of grain boundary conditions on the energy. Different orientations of the materials grain boundary were modeled and molecular dynamic …

Advancing Fluorescent Contrast Agent Recovery Methods For Surgical Guidance Applications, Brook Kennedy Byrd

Dartmouth College Ph.D Dissertations

Fluorescence-guided surgery (FGS) utilizes fluorescent contrast agents and specialized optical instruments to assist surgeons in intraoperatively identifying tissue-specific characteristics, such as perfusion, malignancy, and molecular function. In doing so, FGS represents a powerful surgical navigation tool for solving clinical challenges not easily addressed by other conventional imaging methods. With growing translational efforts, major hurdles within the FGS field include: insufficient tools for understanding contrast agent uptake behaviors, the inability to image tissue beyond a couple millimeters, and lastly, performance limitations of currently-approved contrast agents in accurately and rapidly labeling disease. The developments presented within this thesis aim to address such …

Estimating Vehicle Infrastructure: Downtown Albuquerque, New Mexico, Zachery Phillip Baiamonte

Architecture and Planning ETDs

Cities have little knowledge about their parking infrastructure despite clear evidence that abundant parking has environmental, economic, and transportation consequences. The objective of this thesis is to illustrate the need to accurately estimate the area dedicated to vehicle infrastructure (parking lots and streets) within urban areas. I focused on a method that estimated the vehicle infrastructure area within the Downtown Core of Albuquerque, New Mexico, by cross-referencing geospatial cadastral data with minimum parking requirements. Three parking space types were identified: 1) parking in structures; 2) surface parking (parking lots and residential driveways); and 3) on-street parking. To illustrate the need …

Reduction Of Embodied Carbon In Buildings Through Use Of Low Carbon Strategies And Standardization And Enforcement Of Life Cycle Assessment, Bhargavi Sai Sudhakar

Master's Projects and Capstones

The building and construction industry is energy intensive and as of 2021, this industry is responsible for 37% of the total global greenhouse gas emissions. In previous studies of conventional buildings, the operational energy of a building contributed to 80% and the embodied energy contributed to 20% of the total life cycle energy. With increase in policies and standards that focus on reducing the operational energy, low energy and certified green buildings have emerged where the operational energy has considerably reduced. The relative and absolute share of embodied energy in these energy efficient buildings have increased due to excessive use …

Effects Of Pressure Side Film Cooling Hole Placement And Condition On Surface Heat Transfer Characteristics Of A Transonic Turbine Blade Tip, Hallie Collopy, Phillip M. Ligrani, Hongzhou Xu, Michael Fox

PRC-Affiliated Research

The effects of film cooling hole placement location along the upper pressure side of a transonic squealer are considered. The thermal performance of four different film cooling configurations; B1, B2, B3 and B4, are considered using the University of Alabama in Huntsville's SS/TS/WT (supersonic/transonic/wind tunnel) experimental facility and a simulated turbine blade row using a linear cascade. Surface-varying results are provided for both the squealer blade tip surface, and for the upper pressure side of the squealer blade. These results are given for blowing ratios ranging from 0.42 to 3.20 in the form of spatially-resolved and spatially-averaged adiabatic film cooling …

Data-Driven Power System Stability Analysis And Control, Jian Xie

Electronic Theses and Dissertations, 2020-2023

In recent years, with the expansion of power system size, the increase of interconnection and the use of large-scale renewable energy, power system stability and safe operations have become more prominent, causing challenges to the normal operation of power grid. Traditional analysis rely on detailed models of the system. But for real power systems, the operating state of the system is variable, and the model-based analysis methods may not accurately reflect the real operating state of the system. Therefore, this dissertation is focused on data-driven stability analysis and control. First, a method for locating the oscillation source of multi-machine systems …

High Voltage Aqueous Electrolyte Based Structural Supercapacitors For Electric Vehicles, Deepak Pandey

Electronic Theses and Dissertations, 2020-2023

The current electric vehicles (EVs) face many challenges like limited charge capacity, low miles/charge, and long charging times. Herein, these issues are addressed by developing "energized composite," which is a multifunctional supercapacitor-based energy-storing carbon fiber reinforced polymer composite that can store supplemental electric energy and function as the body shell of EV's. This is achieved by developing a unique design, vertically aligning graphene sheets on carbon fiber electrodes and depositing metal oxides to obtain high energy density electrodes. A high-strength multilayer composite is fabricated using an alternate layer pattern configuration of epoxy and polyacrylamide gel electrolyte. The composite so developed …

Low Noise Front End Signal Transport Design For L-Band Phased Array Receivers, Spencer M. Ammermon

Theses and Dissertations

RF receiver improvements in size, weight, power, and sensitivity are constant goals in the wireless communications community. The combination of phased array antenna systems with high speed analog to digital converters helps engineers meet these goals, because many of the analog components and tasks found in a traditional receive chain are moved into the digital domain. Although the hard work of signal reception is moved into digital signal processing, digital receivers rely on a high performance analog front end to properly condition a signal before analog to digital conversion. In this thesis, two RF front ends are developed for direct …

Ceria Defect Engineering Using Thin-Films/Ald And Biological Applications, Udit Kumar

Electronic Theses and Dissertations, 2020-2023

Ceria nanostructures have been utilized for various engineering applications due to their unique defect structure, enabling them to have regenerative redox properties. The ability to shuttle between Ce3+ and Ce4+ oxidation states extends to unique properties. Defect level in ceria is usually expressed in the Ce3+/Ce4+ ratio. It can be achieved by varying the size(0 to 3D), morphologies, dopants, hetero-nanostructures, and external stimuli. However, it is still a challenge to have precise control over defect structures in the ceria lattice. The current study aims to explore the thin film deposition techniques for cerium oxide using ALD (Atomic layer deposition) and …

Adaptive Analytic Continuation For The State Transition Tensors Of The Two-Body Problem, Tahsinul Haque Tasif

Electronic Theses and Dissertations, 2020-2023

In the past few decades, Kessler syndrome (named after Donald J. Kessler) has become a point of concern in the field of Space Situational Awareness and the future of space missions. It refers to a scenario, where space debris in Earth's orbits collides and creates an exponential increase in space debris numbers leading to more collisions and more debris. In order to handle the resulting challenges like conjunction analysis, tracking, and probability of collisions, the State Transition Matrix (STM) and Tensors (STTs) of the orbit problem play a significant role. In addition, STM and STTs are ubiquitous in spaceflight dynamics, …

Processing And Characterization Of Ultra High Temperature And High Conductive Composites, Haonan Song

Electronic Theses and Dissertations, 2020-2023

There are significant challenges for materials in extreme environments for a variety of applications such as aircraft engines, gas turbines, nuclear reactors, re-entry vehicles, and hypersonic structures. Ceramic matrix composites (CMCs) could be ideal candidates to meet these stringent requirements for materials due to their high melting temperatures, high oxidation, corrosion and ablation resistance, low creep, and thermal cycling behavior in such extreme environments. Particularly, continuous fibers can bridge cracks in CMCs and therefore improve the strength and fracture toughness of composites. Metal matrix ceramics are important materials in various industries, such as aerospace and automobile. MMCs have excellent mechanical …

Performance Analysis Of A Solar-Driven Integrated Direct-Contact Membrane Distillation And Humidification–Dehumidification System, Abdellah Shafieian, Amin Roostaee, Pooria Behnam, Mehdi Khiadani

Research outputs 2022 to 2026

Despite significant advantages of solar-driven membrane-based distillation systems, their large-scale application is limited due to high energy losses, and low technical and economic feasibility. To overcome the mentioned issues, a Direct-Contact Membrane Distillation (DCMD) module (as the primary distillation stage) was coupled with a hollow-fibre membrane-based air humidification–dehumidification (HD) unit (as the secondary distillation stage) to increase the water productivity of the system by recovering some of the lost energy in the first stage. The membrane-based humidifier was designed and implemented instead of the conventional packed columns to avert their drawbacks of being bulky, complex, less durable, and less reliable. …

Polyelectrolyte Functionalized Forward Osmosis For Water Reclamation From Synthetic Spacecraft Wastewater, Alina Ripp

Electronic Theses and Dissertations, 2020-2023

This study investigated the application of a polyelectrolyte (PE)-assisted metallic iron nanoparticle-integrated forward osmosis (FO) membrane to treat synthetic spacecraft wastewater comprising urea, ammonium carbonate, and linear alkylbenzene sulfonate (LAS). The draw solution (MgSO4) diluted via the FO operation was further treated using a nanofiltration (NF) membrane aimed at producing potable quality water by the FO-NF hybrid process. A cellulose triacetate FO membrane was functionalized by layer-by-layer deposition of polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA) followed by incorporating zero valent iron nanoparticles (ZVINP) within the "bilayers". It required 14 bilayers to ensure a uniform coating as demonstrated via scanning …

Distributed Detection In Energy Harvesting Wireless Sensor Networks, Ghazaleh Ardeshiri

Electronic Theses and Dissertations, 2020-2023

A conventional wireless sensor networks (WSN), consisting of sensors powered by nonrechargeable batteries, has a strictly limited lifetime. Energy harvesting (EH) from the environment is a promising solution to address the energy constraint problem in conventional WSNs, and to render these networks to self-sustainable networks with perpetual lifetimes. In EH-powered WSNs, where sensors are capable of harvesting and storing energy, power control is necessary to balance the rates of energy harvesting and energy consumption for data transmission. In addition, wireless communication channels change randomly in time due to fading. These together prompt the need for developing new power control strategies …

Structure And Morphology Of Photoreactive Monomer–Nanoparticle Mixtures Under Patterned Irradiation, Shreyas Pathreeker

Dissertations - ALL

Establishing processing–structure relationships is central to materials science. In this work, we seek answers to whether morphology can be controlled during Light–Induced Self–Writing (LISW) in polymer composite materials, and if yes, how? LISW is based on the ability of light to undergo divergence–free propagation in photoreactive media due to photopolymerization–induced rise in refractive index of the medium. Notably, LISW in polymeric materials has found use predominantly for the fabrication of optical waveguides but has not been explored in polymer–inorganic mixtures. Using through–mask projection which creates a spatially periodic array of optical beams, this work extends LISW to nanoparticle–monomer mixtures to …

Advanced Deep Learning Methodologies For Deepfake Detection, Aminollah Khormali

Electronic Theses and Dissertations, 2020-2023

The recent advances in the field of Artificial Intelligence (AI), particularly Generative Adversarial Networks (GANs) and an abundance of training samples along with robust computational resources have significantly propelled the field of AI-generated fake information in all kinds, e.g., deepfakes. Deepfakes are among the most sinister types of misinformation, posing large-scale and severe security and privacy risks targeting critical governmental institutions and ordinary people across the world. The fact that deepfakes are AI-generated digital content and not actual events captured by a camera implies that they still can be detected using advanced AI models. Although the deepfake detection task has …