Digital Commons Network^™

Engineering 3d Architected Metamaterials For Enhanced Mechanical Properties And Functionalities., Huan Jiang

Electronic Theses and Dissertations

Compared with conventional materials, architected metamaterials have shown unprecedented mechanical properties and functionalities applications. Featured with controlled introduction of porosity and different composition, architected metamaterials have demonstrated unprecedent properties not found in natural materials. Such design strategies enable researchers to tailor materials and structures with multifunctionalies and satisfy conflicting design requirements, such as high stiffness and toughness; high strength with vibration mitigation properties, etc. Furthermore, with the booming advancement of 3D printing technologies, architected materials with precisely defined complex topologies can be fabricated effortlessly, which in turn promotes the research significantly. The research objectives of this dissertation are to achieve …

Convexity Applications In Single And Multi-Agent Control, Olli Nikodeemus Jansson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The focus of this dissertation is in the application of convexity for control problems; specifically, single-agent problems with linear or nonlinear dynamics and multi-agent problems with linear dynamics. A mixture of convex and non-convex constraints for optimal control problems is also considered. The main contributions of this dissertation include: 1) a convexification of single-agent problems with linear dynamics and annular control constraint, 2) a technique for controlling bounded nonlinear single-agent systems, and 3) a technique for solving multi-agent pursuit-evasion games with linear dynamics and convex control and state constraints. The first result shows that for annularly constrained linear systems, controllability …

Modeling, Simulation And Control Of Microrobots For The Microfactory., Zhong Yang

Electronic Theses and Dissertations

Future assembly technologies will involve higher levels of automation in order to satisfy increased microscale or nanoscale precision requirements. Traditionally, assembly using a top-down robotic approach has been well-studied and applied to the microelectronics and MEMS industries, but less so in nanotechnology. With the boom of nanotechnology since the 1990s, newly designed products with new materials, coatings, and nanoparticles are gradually entering everyone’s lives, while the industry has grown into a billion-dollar volume worldwide. Traditionally, nanotechnology products are assembled using bottom-up methods, such as self-assembly, rather than top-down robotic assembly. This is due to considerations of volume handling of large …

Mesoscale Modeling And Machine Learning Studies Of Grain Boundary Segregation In Metallic Alloys, Malek Alkayyali

All Dissertations

Nearly all structural and functional materials are polycrystalline alloys; they are composed of differently oriented crystalline grains that are joined at internal interfaces termed grain boundaries (GBs). It is well accepted that GB dynamics play a critical role in many phenomena during materials processing or under operating environments. Of particular interest are GB migration and grain growth processes, as they influence many crystal-size dependent properties, such as mechanical strength and electrical conductivity.

In metallic alloys, GBs offer a plethora of preferential atomic sites for alloying elements to occupy. Indeed, recent experimental studies employing in-situ microscopy revealed strong GB solute segregation …

Computational Analysis Of Water Braking Phenomena For High-Speed Sled And Its Machine Learning Framework, Jose A. Terrazas

Open Access Theses & Dissertations

Specializing in high-speed testing, Holloman High-Speed Test Track (HHSTT) uses a process called "water braking" as a method to bring vehicles at the test track to a stop. This method takes advantage of the higher density of water, compared to air, to increase braking capability through momentum exchange. By studying water braking using Computational Fluid Dynamics (CFD), forces acting on track vehicles can be approximated and prepared for prior to the actual test. In this study, focus will be made on the brake component of the track sled that is responsible for interacting with the water for braking. By discretizing …

Deep Reinforcement Learning And Game Theoretic Monte Carlo Decision Process For Safe And Efficient Lane Change Maneuver And Speed Management, Shahab Karimi

All Dissertations

Predicting the states of the surrounding traffic is one of the major problems in automated driving. Maneuvers such as lane change, merge, and exit management could pose challenges in the absence of intervehicular communication and can benefit from driver behavior prediction. Predicting the motion of surrounding vehicles and trajectory planning need to be computationally efficient for real-time implementation. This dissertation presents a decision process model for real-time automated lane change and speed management in highway and urban traffic. In lane change and merge maneuvers, it is important to know how neighboring vehicles will act in the imminent future. Human driver …

An Exploration Of The Application Of Desalination In Disaster Relief, Emma Sager

Senior Honors Theses

This paper aims to explore the application of small-scale desalination systems to provide clean water in the wake of marine natural disasters. A lack of clean water is a devastating impact of many natural disasters. Desalination technologies, both thermal and membrane, show potential for being scaled down and self-powered by renewable energy. Desalination can transform ocean water and contaminated drinking water with a high salt content into drinkable, usable water. While these techniques are not perfected, and the solution to a need for clean water is multifaceted, desalination shows potential. Through further research and ever-advancing technology, small-scale desalination could develop …

Rattus Norvegicus As A Biological Detector Of Clandestine Remains And The Use Of Ultrasonic Vocalizations As A Locating Mechanism, Gabrielle M. Johnston

Master's Theses

In investigations, locating missing persons and clandestine remains are imperative. One way that first responder and police agencies can search for the remains is by using cadaver dogs as biological detectors. Cadaver dogs are typically used due to their olfactory sensitivity and ability to detect low concentrations of volatile organic compounds produced by biological remains. Cadaver dogs are typically chosen for their stamina, agility, and olfactory sensitivity. However, what is not taken into account often is the size of the animal and the expense of maintaining and training the animal. Cadaver dogs are typically large breeds that cannot fit in …

Trace Dna Detection Using Diamond Dye: A Recovery Technique To Yield More Dna, Leah Davis

Master's Theses

This study aspires to find a new screening approach to trace DNA recovery techniques to yield a higher quantity of trace DNA from larger items of evidence. It takes the path of visualizing trace DNA on items of evidence with potential DNA so analysts can swab a more localized area rather than attempting to recover trace DNA through the general swabbing technique currently used for trace DNA recovery. The first and second parts consisted of observing trace DNA interaction with Diamond Dye on porous and non-porous surfaces.

The third part involved applying the Diamond Dye solution by spraying it onto …

The Characterization Of Atmospheric Turbulence And Its Effect On Laser Beam Propagation, Michael Cox

All Theses

Having a controlled environment to measure atmospheric turbulence is essential to understanding its effects on different laser beam characteristics. The Clemson Variable Turbulence Generator (VTG) has the capability to propagate a laser beam up to 100 m and be able to dial many turbulence settings up to a heat flux of 357 W/m². A high-speed camera, power detector, and high-resolution temperature probes characterize the VTG with theoretical turbulence spectrums. The exponent associated with the Rayleigh-Bénard (RB) temperature structure constant equation is studied. Two different laser beam profiles are used throughout this work: Gaussian and Asymmetric Perfect Vortex (APV). …

Comparative Design Space For Bistable Composites: An Integrated Framework Of Optimization, Finite Element Analysis, And Experimental Testing, Jonathan Bolanos

All Theses

Bistable composites are a class of advanced materials that can actuate between two stable shapes, making them attractive for a wide range of engineering applications. However, designing these composites to achieve optimal performance remains a challenging task. To address the challenge, this research develops an integrated framework that combines a genetic algorithm optimization technique, finite element analysis in Abaqus, and experimental testing to explore the design comparative space for square bistable composites composed of DA 409 carbon fibers. This leads to the study of generating an optimization algorithm to account for the relationship between the chances of a successful maximum …

A Predictive Analysis Of The Influence Of Thickness And Length On The Curvature Of Square Bistable Carbon Fiber Reinforced Composite Laminates, Stephan Terry

All Theses

This thesis presents a predictive analysis of the stability of square bistable carbon fiber reinforced composite laminates under various loading conditions. The stability of these laminates is essential to their performance and longevity and is influenced by factors such as thickness and length. Analytical and numerical techniques are used to model the behavior of these laminates, and experimental tests are conducted to validate the models. The findings of this research have implications for the design and optimization of square bistable carbon fiber reinforced composites.

The study investigates the relationships between the side length and thickness of square laminates for bistability. …

Design And Data-Driven Identification Of A Quadruped Robot, Dakota Rufino

All Theses

The existence of nonlinearities and the lack of sufficient equations are fundamental challenges in modeling, analyzing, and controlling complex systems. However, recent developments revolutionizing the study of dynamical systems. An emerging method in nonlinear dynamical systems is the Koopman operator theory, which provides us with key advantages in performing the modeling, prediction, and control of nonlinear systems. The linear system representation allows us to leverage linear stability analysis. The first section of this thesis briefly covers the construction of a quadrupedal robot, a sufficiently complex nonlinear dynamical system, for the use of analyzing data-driven modeling techniques. The second section details …

Using Immersive Technology To Improve Mechanical Design: Use Cases, A Review Of Current Technology, And An Experiment In Requirement Elicitation In Virtual Reality, William Hawthorne

All Theses

There has been a growing trend in the use of immersive technologies within engineering design. This research is focused on understanding how Virtual Reality (VR) technologies support design reviews. Modern tools including virtual reality hardware and software were tested for current capabilities and challenges. In a review of literature, two key gaps are identified: the rapid advancements of VR and AR technology and limited formal studies to determine the costs and benefits of immersive technology within engineering design reviews. This research has resulted in three key outcomes. First, use cases of immersive reality technologies are identified, through the lens of …

Using Actor-Critic Reinforcement Learning For Control Of A Quadrotor Dynamics, Edgar Adrian Torres

Theses and Dissertations

This paper presents a quadrotor controller using reinforcement learning to generate near-optimal control signals. Two actor-critic algorithms are trained to control quadrotor dynamics. The dynamics are further simplified using small angle approximation. The actor-critic algorithm’s control policy is derived from Bellman’s equation providing a sufficient condition to optimality. Additionally, a smoother converter is implemented into the trajectory providing more reliable results. This paper provides derivations to the quadrotor’s dynamics and explains the control using the actor-critic algorithm. The results and simulations are compared to solutions from a commercial, optimal control solver, called DIDO.

Engineered Material Systems For Mimicking Tissue And Disease, Margrethe Ruding

McKelvey School of Engineering Graduate Student Theses & Dissertations

This thesis comprises two studies involving design and application of soft material systems. The goal of the first study was to design, fabricate, and characterize hydrogel lattice structures with consistent, controllable, anisotropic mechanical properties. Lattices, based on four types of unit cells (cubic, diamond, vintile, and Weaire-Phelan), were printed using stereolithography (SLA) of polyethylene glycol diacrylate (PEGDA). In order to create structural anisotropy in the lattices, unit cell design files were scaled in one direction by a factor of two in each layer and then printed. The mechanical properties of the scaled lattices were measured in shear and compression and …

An Investigation Of Soft Electrohydraulic Actuators: Theory, Characterization, And Conceptual Applications, Alexandrea Washington

UNLV Theses, Dissertations, Professional Papers, and Capstones

Electroactive polymer (EAP) materials are a novel soft electromechanical device that exploits the inherent electrical and mechanical advantages of flexible polymer materials. Within this groundbreaking field there are various actuator and sensor devices that have been developed for a variety of applications, from medical devices to artificial biological systems. This research focuses on electrohydraulic actuators, which are comprised of a flexible conductive medium, a dielectric fluid, and a compliant film material to encapsulate the dielectric fluid. This specific study centers around the electrohydraulic EAP actuator known as the Hydraulically Amplified Self-Healing Electrostatic (HASEL) actuator, first introduced by the Keplinger group …

Developing Executable Digital Models With Model-Based Systems Engineering – An Unmanned Aerial Vehicle Surveillance Scenario Example, Viviana Guadalupe Lopez

Theses and Dissertations

There is an increase in complexity in modern systems that causes inconsistencies in the iterative exchange loops of the system design process and in turn, demands greater quality of system organization and optimization techniques. A recent transition from document-centric systems engineering to Model-Based Systems Engineering (MBSE) is being documented in literature from various industries to address these issues. This study aims to investigate how MBSE can be used as a starting point in developing digital twins (DT). Specifically, the adoption of MBSE for realizing DT has been investigated, resulting in various literature reviews that indicate the most prevalent methodologies and …

Wave Excited Mass-Spring-Damper System For A Self-Recharging Autonomous Underwater Vehicle, Mahmodul Hasan Maheen

Theses and Dissertations

Autonomous underwater vehicles' (AUVs) endurance is constrained by the lifetime of their batteries and the distance that tether wires can traverse. Solving the endurance problem of AUV using the enormous potential of ocean wave energy is the motivation behind this thesis. The objective of this research is to model a mass-spring-damper system to emulate the permanent magnet linear generator (PMLG) of a self-recharging AUV and identify its energy absorption capability through numerical simulation and experimental testing. The research activities started with modeling and fabricating a 1:5 scale model. The scaling was done by comparing the most common AUV size of …

2023 (Spring) Ensi Informer Magazine, Morehead State University. Engineering Sciences Department

ENSI Informer Magazine Archive

The ENSI Informer Magazine published in the spring of 2023.

Understanding The Effectiveness Between Modern Technologies And Traditional Training Methods Of E-Learning On An Individual’S Learning Curve, Content Retention, And Satisfaction, Andressa Camacho Ortiz

Theses and Dissertations

E-learning has become a widespread and valuable tool for skill development. After the COVID-19 pandemic, the necessity and adaptability of this method increased drastically. Hence, numerous studies focused on understanding the effectiveness of this method. The academic literature highlights the need to explore alternative solutions that can increase a learner’s content retention and satisfaction when learning remotely. Modern technologies can be a great solution for this need with the correct application and development. This thesis analyzes the effects of technology on content retention, satisfaction, and learning curve through the following technologies: online platform, virtual reality (VR), and hologram display. A …

Predicting Near-Bed Sediment Transport Through Particle Image Velocimetry, Caroline Hoch

Theses and Dissertations

Erosion and accretion are coastal processes that directly affect the safety of coastal communities. Dimensionless parameters, such as the Shields and Ursell number, have historically been used to predict sediment motion in the nearshore region based on shear stress and wave linearity. This study uses particle image velocimetry to measure the velocity field of sediment within a wave flume and calculate these parameters for various wave profiles. Five regular wave trials and five irregular wave trials were run within the wave flume at varying depths to model how net transport changes as waves approach the shoreline. An instantaneous Shields number …

A Method For Measuring The Spectral Emissivity Of Metal Powders At Different Temperatures And Applications In Laser Powder Bed Fusion, Emmanuel Levario

Open Access Theses & Dissertations

Radiation thermometry monitoring methods used in powder bed fusion additive manufacturing (PBF-AM) are becoming increasingly more popular for quality assurance and repeatability. The dynamic nature of the PBF process and a lack of accuracy of metrics being captured for temperature monitoring lend great difficulty in the successful implementation of in-situ monitoring. There is currently no data on the emissivity, a metric used in non-contact temperature measurements, for metal powders used in AM. This work describes a method for measuring the spectral emissivity for metal powder sizes commonly used in AM using a multi-wavelength (MW), FMPI SpectroPyrometer, calibrated within the spectral …

Heat Transfer Of A 1n Thruster In A 2.5u Cubesat Module, Javier Madrid

Open Access Theses & Dissertations

With the aerospace industry expanding and moving forward with more ambitious missions, small satellites such as CubeSats have proven to be at the forefront of innovation for research satellites. This innovation have introduced complications which if gone unattended can lead to the loss of the satellite; one such complication coming in the form of propulsion heat transfer. This paper presents an investigation into the propagation of heat transfer within a 2.5 CubeSat module when a 1N thruster is fired inside it. This is done by leveraging the equation of heat transfer and comparing results to those simulated by ANSYS. Not …

Near-Optimal Control Of A Quadcopter Using Reinforcement Learning, Alberto Velazquez-Estrada

Theses and Dissertations

This paper presents a novel control method for quadcopters that achieves near-optimal tracking control for input-affine nonlinear quadcopter dynamics. The method uses a reinforcement learning algorithm called Single Network Adaptive Critics (SNAC), which approximates a solution to the discrete-time Hamilton-Jacobi-Bellman (DT-HJB) equation using a single neural network trained offline. The control method involves two SNAC controllers, with the outer loop controlling the linear position and velocities (position control) and the inner loop controlling the angular position and velocities (attitude control). The resulting quadcopter controller provides optimal feedback control and tracks a trajectory for an infinite-horizon, and it is compared with …

Machine Learning-Based Data And Model Driven Bayesian Uncertanity Quantification Of Inverse Problems For Suspended Non-Structural System, Zhiyuan Qin

All Dissertations

Inverse problems involve extracting the internal structure of a physical system from noisy measurement data. In many fields, the Bayesian inference is used to address the ill-conditioned nature of the inverse problem by incorporating prior information through an initial distribution. In the nonparametric Bayesian framework, surrogate models such as Gaussian Processes or Deep Neural Networks are used as flexible and effective probabilistic modeling tools to overcome the high-dimensional curse and reduce computational costs. In practical systems and computer models, uncertainties can be addressed through parameter calibration, sensitivity analysis, and uncertainty quantification, leading to improved reliability and robustness of decision and …

A Value-Based Sequential Optimization Framework For Efficient Materials Design Considering Uncertainty And Variability, Maher Alghalayini

All Dissertations

Many problems in engineering and science can be framed as decision problems in which we choose values for decision variables that lead to desired outcomes. Notable examples include maximizing lift in airplane wing design, improving the efficiency of a power plant, or identifying processing protocols resulting in structural materials with desired mechanical properties. These problems typically involve a significant degree of uncertainty about the often-complex underlying relationships between the decision variables and the outcomes. Solving such decision problems involves the use of computational models or physical experimentation to generate data to make predictions and test hypotheses. As a result, both …

A Unified Understanding Of Minimum Lattice Thermal Conductivity, Yi Xia, Dale Gaines, Jiangang He, Koushik Pal, Zhi Li, Mercouri G. Kanatzidis, Vidvuds Ozolinš, Chris Wolverton

Mechanical and Materials Engineering Faculty Publications and Presentations

We propose a first-principles model of minimum lattice thermal conductivity based on a unified theoretical treatment of thermal transport in crystals and glasses.

Heat Transfer In Microchannel Compact Heat Exchanger, Mohammed Al-Khateri

Theses

This study aims to investigate heat transfer in a miniaturized channel heat exchanger and effectiveness for given real-life design. The main objective of the study is to develop and build a high-performance heat exchanger for thermal management in automotive application using typical radiator manufacturing techniques. This research uses experimental and model-based investigation. It conceptualizes the Miniaturized Channel Heat Exchangers (MCHX) model-based study for demonstrating the design of miniaturized channel heat exchangers, manufacture, and study the heat exchanger effectiveness by validating the developed mathematical model experimentally. The proposed design of the MCHX is to use extruded tubes containing miniaturized channels as …

Improving The Learning Efficiency Of Adaptive Optimal Control In Information-Limited Environments, Omar Ghassan Qasem

Theses and Dissertations

This work investigates the adaptive optimal control problems for continuous-time linear and nonlinear systems. A novel adaptive dynamic programming method, namely hybrid iteration (HI) is presented. Different from the existing adaptive dynamic programming methods, i.e., policy iteration (PI) and value iteration (VI), the HI does not require an initial admissible control policy compared to the PI. On the other hand, the HI converges to the optimal control policy in much less learning iterations and CPU time compared to the VI due to the ensured quadratic rate of convergence of the HI method, which is much faster than the sub-linear convergence …