Engineering Commons^™

An Analytical Method Of Switching Waveform Design For Harmonic Elimination, Sraddhanjoli Bhadra

Theses and Dissertations

In this dissertation, we have investigated an analytical approach for solving a set of transcendental equations commonly encountered in Selective Harmonic Elimination (SHE). Generally, numerical solutions are used to solve the transcendental equations, which require guessing of an initial value and a valid value of modulation index m. Invalid initial values and an invalid m affect convergence. Such difficulties can be avoided with analytical solutions. The solution set will also determine the possible range of m valid for that modulation. Due to the complexity of solution that often requires computer algorithm to find a solution, we plan to develop design …

Helipad Detection From Satellite Imagery Using Convolutional Neural Networks, David Specht

Theses and Dissertations

Location data about U.S. heliports is often inaccurate or nonexistent in the FAA's databases, which leaves pilots and air ambulance operators with inaccurate information about where to find safe landing zones. In the 2018 FAA Reauthorization Act, Congress required the FAA to collect better information from the helicopter industry under part 157, which covers the construction, alteration, activation and deactivation of airports and heliports. At the same time, there is no requirement to report private helipads to the FAA when constructed or removed, and some public heliports do not have up to date records. This thesis proposes an autonomous system …

A Laboratory Investigation Of High Polymer Modified Asphalt Mixtures With Softening Agent, Basel K. Al-Badr

Theses and Dissertations

This study was initiated to evaluate the impact of aging and High Polymer Modified Asphalt (HPMA) binders containing a bio-based-oil softening agent (SA) on the rutting, cracking, and durability of asphalt mixtures. One control asphalt binder (PG 52-34), Styrene-Butadiene-Styrene (SBS) polymer modifier, and corn-oil SA were used to produce four asphalt mixtures including a control prepared using PG 52-34 binder and three modified mixtures were produced by blending PG 52-34 binder with different dosages of SBS and SA. The mixtures were tested using the Dynamic Complex Modulus (|E*|), Hamburg Wheel Tracking Device (HWTD), Flow Number (FN), Indirect Tension Cracking Test …

Effects Of Stiffness And Cell Shape On Cellular Mechanosensing, Sarah Lynn Furman

Theses and Dissertations

Cellular mechanosensing is the process of converting mechanical signals into biological responses. Stem cells are self-renewing cells with the potential to transform into specialized cell types - this differentiation process is influenced by cellular mechanosensing. Cells sense material stiffness, and stiffer environments result in increased cellular mechanosensing and preferential differentiation into bone-producing osteoblasts. Cell shape also plays an important role due to its influence on cytoskeletal contractility, and photopatterning can be used to study the effects of cell shape on cellular mechanosensing. Although the effects of material stiffness and cell shape have been studied, little is known about the joint …

Estimation Of Able-Bodied Humans Elbow Joint Actions Using Semg And Ann-Based Softmax Classifier, Abdullah Al-Maliki

Theses and Dissertations

The upper limb is a complex part of the human body, and it is necessary to carry on daily tasks and maintain self-dependence. As a result, the daily life of people with upper limb amputation could not be as easy or as free as the more fortunate people without amputation. This work focuses on estimating the upper limb’s angular displacement, speed, acceleration, and torque at the elbow joint, it does so regardless of arm’s orientation and effort level. We do so to enable better control of the myoelectric prosthesis. This work complements the related existing literature, which usually does not …

Performance Evaluation Of 5g Cloud Radio Access Networks Using New Fading Channel Models, Ayad Nafe Bihnam

Theses and Dissertations

The exponential demand for high-speed networks and data processing forces mobile network operators to develop new solutions to cope with the current indigence. The desire for more reliable, power-efficient, cost-efficient networks arises due to increasing smartphones, tablets, and applications that demand data-hungry applications. Various solutions and technologies have been proposed to cope with these challenges where Cloud Radio Access Network (C-RAN) is one among many others. In C-RAN, the baseband units are decoupled from the Remote Radio Heads (RRHs) and transferred to the cloud to enable centralized, supporting, controlling, and data processing. The RRHs, on the other hand, are considered …

Porous Scaffold And Soft Hydrogel Composite For Biomedical Applications, Matthew Dicerbo

Theses and Dissertations

Biophysical signals including stiffness and dimensionality influence a myriad of stem cell behaviors including morphology, mechanosensing, and differentiation. 2D stiff environments cause increased cellular spreading and induce osteogenic differentiation whereas 3D soft environments favor rounder cell morphologies attributed to a chondrogenic phenotype. The goal of this study is to create a composite that integrates these divergent biophysical signals within one system. This composite consists of a stiff and porous polycaprolactone (PCL) backbone that provides mechanical stiffness and a 2D environment. The PCL backbone is then perfused with mesenchymal stem cells (MSCs) and a soft methacrylated gelatin (GelMe) hydrogel to provide …

Design Of A Pneumatic Soft Robotic Actuator Using Model-Based Optimization, Mahsa Raeisinezhad

Theses and Dissertations

In this thesis, the design and optimization process of a novel soft intelligent modular pad (IntelliPad) for the purpose of pressure injury prevention is presented. The structure of the IntelliPad consists of multiple individual multi-chamber soft pneumatic-driven actuators that use pressurized air and vacuum. Each actuator is able to provide both vertical and horizontal motions that can be controlled independently. An analytical modeling approach using multiple cantilever beams and virtual springs connected in a closed formed structure was developed to analyze the mechanical performance of the actuator. The analytical approach was validated by a finite element analysis. For optimizing the …

Investigation Of Single, Binary, And Ternary Metal Oxides Of Iridium, Rhodium, And Palladium For Neural Interfacing Applications, Gregory Vincent Taylor

Theses and Dissertations

In this dissertation, thin film single, binary, and ternary metal oxides of iridium (Ir), ruthenium (Ru), rhodium (Rh), and palladium (Pd) were synthesized for use as electrode/microelectrode coatings for neural interfacing applications using DC reactive magnetron sputtering. Synthesis conditions which enhanced the electrochemical properties of films as measured by cyclic voltammetry and electrochemical impedance spectroscopy in a phosphate buffered saline solution of the single metal oxides were identified to be 30 mTorr working pressure, 20% oxygen partial pressure, and cathode power densities ≤ 4.9 W/cm². These parameters were then used to develop the binary and ternary metal oxide …

A New Method Of Measuring Flow Stress For Improved Modeling Of Friction Stir Welding, David John Prymak

Theses and Dissertations

Deficiencies in friction stir welding (FSW) numerical modelling are identified. Applicability of flow stress data derived from hot compression, hot torsion, and split Hopkinson bar testing methods is assessed. A new method of measuring flow stresses in the stir zone of a friction stir welding tool is developed. This test utilizes a non-consumable flat-faced cylindrical tool of different geometries that induces a vertical and rotational load on the material of interest. A constant vertical load and rpm value is used for each test yielding the resulting motor torque and temperature generation to define the material response. Experimental samples are cross-sectioned, …

Zero-Energy Tuning Of Silicon Microring Resonators Using 3d Printed Microfluidics And Two-Photon Absorption Induced Photoelectrochemical Etching Of Silicon, Kevin Eugene Larson

Theses and Dissertations

This thesis presents a novel method of modulating silicon photonic circuits using 3D printed microfluidic devices. The fluids that pass through the microfluidic device interact directly with the silicon waveguides. This method changes the refractive index of the waveguide cladding, thus changing the effective index of the system. Through using this technique we demonstrate the shift in resonant wavelength by a full free spectral range (FSR) by increasing the concentration of the salt water in the microfluidic device from 0% to 10%. On a 60 μm microring resonator, this equals a resonant wavelength shift of 1.514 nm when the index …

Life Cycle Climate Performance Assessment For R1234yf As A Low Gwp Drop-In Alternative For R134a In Domestic Refrigerators, Mohamed Ragab Senosey Khaled Zain

Theses and Dissertations

Aligning with the global movements towards mitigating CO2 emissions and regulations to phase out HFC refrigerants, many low GWP refrigerants are being tested and proposed as fourth-generation refrigerants. R1234yf is a refrigerant with a GWP of less than one and has a high potential to replace R134a, which has a GWP of 1300, and it is the most commonly used refrigerant in domestic refrigerators. In this study, an energy performance evaluation and a life cycle climate performance assessment for R1234yf were conducted and compared to those of R134a based on a baseline domestic defrost refrigerators. Four different charges of R1234yf …

High-Speed Image Classification For Resource-Limited Systems Using Binary Values, Taylor Scott Simons

Theses and Dissertations

Image classification is a memory- and compute-intensive task. It is difficult to implement high-speed image classification algorithms on resource-limited systems like FPGAs and embedded computers. Most image classification algorithms require many fixed- and/or floating-point operations and values. In this work, we explore the use of binary values to reduce the memory and compute requirements of image classification algorithms. Our objective was to implement these algorithms on resource-limited systems while maintaining comparable accuracy and high speeds. By implementing high-speed image classification algorithms on resource-limited systems like embedded computers, FPGAs, and ASICs, automated visual inspection can be performed on small low-powered systems. …

Behavior Of Unreinforced Lightweight Cellular Concrete Backfill For Reinforced Concrete Retaining Walls, Ryan Jeffrey Wilkinson

Theses and Dissertations

Lightweight cellular concrete (LCC) is a mixture of cement, water and foam, with a density less than 50 pcf. This material is being used increasingly often in a variety of construction applications due to its self-leveling, self-compacting, and self-consolidating properties. LCC may be used as a backfill or structural fill in areas where traditional granular backfill might normally be used. This material may be especially advantageous in areas where the underlying soil may not support the weight of a raised earth embankment. Testing on the behavior of LCC when used as backfill behind retaining walls is relatively limited. The effects …

An Evaluation Of Electrically Conductive Asphalt Mixtures For Electrically Heated Flexible Pavement Systems, Rahaf Hasan

Theses and Dissertations

The goal of this study is to develop Electrically Conductive Asphalt (ECA) mixtures with optimized electrical and mechanical properties for use in electrically heated asphalt pavements for anti-icing applications. Laboratory experiments were carried out to design ECA mixtures at varying dosages, using three graphite grades of different particle sizes, one virgin aggregate type, two binder grades, and one carbon fiber. The impact of graphite dosage and particle size on the volumetric properties and electrical resistivity of asphalt mixtures was assessed. Different factors with potential impact on the electrical properties were investigated, including the graphite particle size and dosage, the air …

Understanding Quote-Tweet Usage During The Covid-19 Pandemic, David Hardy Bean

Theses and Dissertations

The Covid-19 pandemic first entered the international news cycle with mixed levels of concern. How did people across the globe react to first encounters with this virus? For many it was like seeing for the first time the spewing ash of a volcano, or the receding tides of a tsunami. Many reacted with disbelief, not knowing the proper course of action for themselves or for their community. This study explores the topics of discussion and reactions to the pandemic through the lens of quote-tweets--from the initial confusion and disbelief to the eventual politicization, economic closures, and reopening events. Quote-tweets are …

In Situ Characterization Of Fiber-Matrix Interface Debonding Via Full-Field Measurements, Robert Livingston

Theses and Dissertations

Macroscopic mechanical and failure properties of fiber-reinforced composites depend strongly on the properties of the fiber-matrix interface. For example, transverse cracking behavior and interlaminar shear strength of composites can be highly sensitive to the characteristics of the fiber-matrix interface. Despite its importance, experimental characterization of the mechanical behavior of the fiber-matrix interface under normal loading conditions has been limited. This work reports an experimental approach that uses in situ full-field digital image correlation (DIC) to quantify the mechanical and failure behaviors at the fiber-matrix interface. Single fiber model composite samples are fabricated from a proprietary epoxy embedding a single glass …

The Matrix Revisited: A Critical Assessment Of Virtual Reality Technologies For Modeling, Simulation, And Training, George Demetrius Lecakes

Theses and Dissertations

A convergence of affordable hardware, current events, and decades of research have advanced virtual reality (VR) from the research lab into the commercial marketplace. Since its inception in the 1960s, and over the next three decades, the technology was portrayed as a rarely used, high-end novelty for special applications. Despite the high cost, applications have expanded into defense, education, manufacturing, and medicine. The promise of VR for entertainment arose in the early 1990's and by 2016 several consumer VR platforms were released. With VR now accessible in the home and the isolationist lifestyle adopted due to the COVID-19 global pandemic, …

Fluid-Structure Interaction Of Nrel 5-Mw Wind Turbine, Mohamed Sayed Elkady Abd-Elhay

Theses and Dissertations

Wind energy is considered one of the major sources of renewable energy. Nowadays, wind turbine blades could exceed 100 m to maximize the generated power and minimize produced energy cost. Due to the enormous size of the wind turbines, the blades are subjected to failure by aerodynamics loads or instability issues. Also, the gravitational and centrifugal loads affect the wind turbine design because of the huge mass of the blades. Accordingly, wind turbine simulation became efficient in blade design to reduce the cost of its manufacturing. The fluid-structure interaction (FSI) is considered an effective way to study the turbine's behavior …

On-Chip Nanoscale Plasmonic Optical Modulators, Abdalrahman Mohamed Nader Abdelhamid

Theses and Dissertations

In this thesis work, techniques for downsizing Optical modulators to nanoscale for the purpose of utilization in on chip communication and sensing applications are explored. Nanoscale optical interconnects can solve the electronics speed limiting transmission lines, in addition to decrease the electronic chips heat dissipation. A major obstacle in the path of achieving this goal is to build optical modulators, which transforms data from the electrical form to the optical form, in a size comparable to the size of the electronics components, while also having low insertion loss, high extinction ratio and bandwidth. Also, lap-on-chip applications used for fast diagnostics, …

Cross-Junction Based Metasurfaces: A Roadmap To Fano Resonances, Mirna Soliman

Theses and Dissertations

The first part of the thesis presents a summary of the classification of materials, followed by the development of metamaterials and their salient role. Then, a study of metamaterials and the evolution of these 3D structures to 2D, known as metasurfaces, have been discussed. Moreover, the physics and practical interest behind Fano resonance have been discussed. Furthermore, the physical fundamentals guiding the performance of both the metamaterials and metasurfaces, including the temporal coupled-mode theory and the generalized laws of reflection and refraction, have been intensely investigated, along with some of the outstanding properties of the metamaterials. Then, a comparison between …

Fabrication And Characterization Of Translucent Wood Composite Using Egyptian Hardwoods: Casuarina & Eucalyptus, Sherif Elia

Theses and Dissertations

Due to climate change and global warming, there is an increasing need for sustainable solutions in all industries. As one of the most important and growing industries worldwide, the construction industry has a huge responsibility towards the environment. It is responsible for the consumption of vast amounts of resources and consequently generating massive quantities of waste. Also, as the building sector is responsible for consuming large portions of the world energy and electricity, such buildings' efficiency and sustainability must be considered. While the world is working on balancing between consuming less and recycling more while maintaining the construction materials' effectiveness …

A Framework For Assessing And Designing Human Annotation Practices In Human-Ai Teaming, Suzanne Ashley Stevens

Theses and Dissertations

This thesis work examines how people accomplish annotation tasks (i.e., labelling data based on content) while working with an artificial intelligence (AI) system. When people and AI systems work together to accomplish a task, this is referred to as human-AI teaming. This study reports on the results of an interview and observation study of 15 volunteers from the Washington DC area as the volunteers annotated Twitter messages (tweets) about the COVID-19 pandemic. During the interviews, researchers observed the volunteers as they annotated tweets, noting any needs, frustrations, or confusion that the volunteers expressed about the task itself or when working …

Interactive Expert System For Budgeting World Bank Consultancy Projects, Yosra Rafat

Theses and Dissertations

Cost estimating and forecasting are key components of the budgeting of any construction project. However, conventional approaches may result in uncertainty and usually do not utilize the organizational knowledge of past projects. Ideally, performing a cost estimation under the best predictions of the relevant future conditions, is the best approach of economic analysis to evaluate the optimum value for money. With the rise of Artificial Intelligence techniques, there are now several Machine Learning (ML) methods that are being studied to capitalize on accuracy gains with regards to cost estimating techniques to increase reliability during the tendering phase. This research aims …

Off-Chain Transaction Routing In Payment Channel Networks: A Machine Learning Approach, Heba Kadry

Theses and Dissertations

Blockchain is a foundational technology that has the potential to create new prospects for our economic and social systems. However, the scalability problem limits the capability to deliver a target throughput and latency, compared to the traditional financial systems, with increasing workload. Layer-two is a collective term for solutions designed to help solve the scalability by handling transactions off the main chain, also known as layer one. These solutions have the capability to achieve high throughput, fast settlement, and cost efficiency without sacrificing network security. For example, bidirectional payment channels are utilized to allow the execution of fast transactions between …

Assessment Of Carbon Dioxide Emission And Its Impact On High-Rise Mixed-Use Buildings In Egypt, Ahmed Salah Hamza

Theses and Dissertations

With Egypt's vision of 2030 focusing on sustainable development with a true emphasis on Carbon Dioxide (CO₂) emission reduction in the newly built cities and high-rise buildings, efforts are exerted on various levels towards accomplishing the vision’s goals. This is achieved through multiple tools and models associated with aiding the reduction of carbon emissions, yet not a clear one was introduced for the mixed-use buildings in Egypt.

Through this work, a significant gap was identified with respect to high-rise buildings carbon emission assessment in Egypt. This was a main driving force for this work in an attempt to …

Stock Market Manipulation Detection Using Continuous Wavelet Transform & Machine Learning Classification, Sarah Youssef

Theses and Dissertations

Stock market manipulation detection is important for both investors and regulators. Being able to detect stock manipulation and preventing it gives investors the confidence in the market fairness and integrity. It also helps maintaining liquidity of the stocks and market efficiency. Implementing data mining algorithms in manipulation detection is a relatively recent technique but in the past few years there has been an increasing interest in it's applications in this domain. The benefit of monitoring manipulative trade behavior is that it can be implemented on live feed of stock data, which saves a lot of time in detecting stock price …

Effective Temperature Control For Industrial Friction Stir Technologies, Arnold David Wright

Theses and Dissertations

Systematic investigation of the Friction Stir Welding (FSW) process shows that a fixed rotational velocity and feed rate may not yield uniform mechanical properties along the length of a weldment. Nevertheless, correlations between process parameters and post-weld material properties have successfully demonstrated that peak temperature and cooling rate drive post-weld properties. There have been many reported methodologies for controlling friction stir welding, with varying degrees of cost to implement and effectiveness. However, comparing data from uncontrolled FSW of AA 6111-T4 sheet with controlled FSW at temperatures ranging from 375 °C to 450 °C demonstrates that a simplified methodology of a …

Certifying Computer Forensics Skills, Michael Charles Watson

Theses and Dissertations

Computer forensics is an ever-growing technological field of complexity and depth. Individuals must strive to keep learning and growing their skills as they help combat cybercrime throughout the world. This study attempts to establish a method of evaluating conceptual expertise in computer forensics to help indicate whether or not an individual understands the five basic phases of computer forensics: preparation, seizure of evidence, acquisition of data, analysis of data, and reporting the findings of the analysis. A survey was presented to a university class of 30 students taking a computer forensics course and as well as posted online asking computer …

Rebalancing Shared Mobility Systems By User Incentive Scheme Via Reinforcement Learning, Matthew Brian Schofield

Theses and Dissertations

Shared mobility systems regularly suffer from an imbalance of vehicle supply within the system, leading to users being unable to receive service. If such imbalance problems are not mitigated some users will not be serviced. There is an increasing interest in the use of reinforcement learning (RL) techniques for improving the resource supply balance and service level of systems. The goal of these techniques is to produce an effective user incentivization policy scheme to encourage users of a shared mobility system to slightly alter their travel behavior in exchange for a small monetary incentive. These slight changes in user behavior …