Engineering Commons^™

Gps-Denied Localization Of Daughter-Ships In A Mother-Daughter Ship Collaborative Environment, Ethan W. Jacquin

Theses and Dissertations

This research investigates the possibility of using the communication link between a mothership and daughter-ship UAV and an Extended Kalman Filter algorithm as a replacement of GPS, assuming a ranging link exists between the mothership and daughter-ship and that the mothership is GPS-enabled. A simulation study examines the viability of the approach and the effect of parameters such as distance, altitude, roll angle, speed, ranging sensor noise, and inertial measurement unit uncertainty were considered. The magnitude of the errors between predicted and measured position were examined and a range of acceptable flight parameters was formed.

Charge Mitigation Technologies For Aircraft Platforms, Mitchell L. Rudy

Theses and Dissertations

Research into ion-based advanced propulsion systems, such as air-breathing Hall effect thrusters on high-velocity aircraft and ion-propelled thrusters on spacecraft, necessitates addressing accompanying residual electric charge accumulation on the ungrounded flight platform. An experimental testbed was constructed to assess charge mitigation technologies and their effectiveness on aircraft. A Van de Graaff generator provided static charge accumulation levels exceeding a megavolt when combined with a high voltage direct current source generator. This research attached an isolated airfoil structure to the Van de Graaff generator's lower terminal to measure the induced leakage current under various applied environmental conditions, including up to three …

Evaluation Of Efficient Water Reuse Technologies For Sustainable Forward Operating Bases, Kelsie L. Crouch

Theses and Dissertations

A secure water source is essential to the resiliency and readiness of military installations and contingency operation locations, especially those located in the dry climates the US military operates in today. There are multiple issues of concern when identifying water sources, such as security, cleanliness, accessibility, and sustainability. Water resources pose a potential vulnerability to mission readiness in a remote, agile environment, such as a forward operating base (FOB). Having a secure water resource helps facilitate mission readiness in the contingency environment, offering the opportunity to be more resilient and cost-effective. Current water treatment technologies present the possibility to perform …

Conversion From Coal To Natural Gas At Wright Patterson Air Force Base: An Analysis And Case Study, Tyler A. Ferry

Theses and Dissertations

Over the last 20 years, natural gas has replaced coal as the preferred fossil fuel for heat and power generation across the United States, due to its increased prevalence, lower cost, and reduced environmental impacts. While most conversion decisions are driven by cost savings, proponents of energy transitions often cite emissions reductions as a tangential benefit. Over the same time, climate change and its impact on the environment and society have come to the forefront of scientific inquiry. One example of the transition from coal to natural gas can be found in Dayton, Ohio. Wright Patterson Air Force Base (WPAFB) …

Real-Time Aerial Magnetic And Vision-Aided Navigation, Daniel J. Clarke

Theses and Dissertations

Aerial magnetic navigation has shown to be a viable alternative navigation method that has the potential for world-wide availability, to include over oceans. Obtaining GPS-level accuracy using magnetic navigation alone is challenging, but magnetic navigation can be combined with other alternative navigation methods that are more posed to obtaining GPS-level accuracy in their current state. This research presents an aerial navigation solution combining magnetic navigation and vision-aided navigation to aid an inertial navigation system (INS). The navigation solution was demonstrated in real-time playback using simulated magnetic field measurements and flight-test captured visual imagery. Additionally, the navigation solution was flight-tested on …

Examining How Standby Assets Impact Optimal Dispatching Decisions Within A Military Medical Evacuation System Via A Markov Decision Process Model, Kylie Wooten

Theses and Dissertations

The Army medical evacuation (MEDEVAC) system ensures proper medical treatment is readily available to wounded soldiers on the battlefield. The objective of this research is to determine which MEDEVAC unit to task to an incoming 9-line MEDEVAC request and where to station a single standby unit to maximize patient survivability. A discounted, infinite-horizon continuous-time Markov decision process model is formulated to examine this problem. We design, develop, and test an approximate dynamic programming (ADP) technique that leverages a least squares policy evaluation value function approximation scheme within an approximate policy iteration algorithmic framework to solve practical-sized problem instances. A computational …

An Analysis Of Stability In Software Resources Data Report (Srdr) Computer Software Configuration (Csci), Trevor J. Violette

Theses and Dissertations

This research studies cost and schedule stability in programs that utilize Software Resource Data Report (SRDR) reporting standards. We find software programs at the Computer Software Configuration Item (CSCI) level show much lower levels of stability than previously published DoD stability research that focused on aircraft. A comparison of software development methods found little to no difference between Agile and Plan Driven methodologies. Critical Success Factors (CSF) were identified from prior literature and used to examine CSCIs from the SRDR dataset. Focusing on schedule or cost resulted in different variables showing significance. A CSCI is more likely to remain on …

Computational Electromagnetic Modeling Of Metasurface Optical Devices With Defect Study, Carlos D. Diaz

Theses and Dissertations

One of the first fabricated metasurface optical devices, the in-plane V-antenna lenses, were plagued by a fundamental transmission limit (<25 >). Two distinct sets of Out-of-Plane phase elements were designed with improved transmission (~60 ). These were fabricated as beamsteerers and characterized in terms of their Bidirectional Transmittance Distribution Function measured as a function of scatter angle. Experimental data from the beamsteerers was analyzed via simulations using a finite element method (FEM). The measurements showed the designed beamsteering, but also a strong zero-order diffraction not present in the simulations, which motivated this study to understand what was causing these differences. …

Latency Optimization In Smart Meter Networks, Amr Kassab

Theses and Dissertations

In this thesis, we consider the problem of smart meter networks with data collection to a central point within acceptable delay and least consumed energy. In smart metering applications, transferring and collecting data within delay constraints is crucial. IoT devices are usually resource-constrained and need reliable and energy-efficient routing protocol. Furthermore, meters deployed in lossy networks often lead to packet loss and congestion. In smart grid communication, low latency and low energy consumption are usually the main system targets. Considering these constraints, we propose an enhancement in RPL to ensure link reliability and low latency. The proposed new additive composite …

Dewetting Induced Lipid Bilayer Multicomponent Scaffold For Synthetic Cell Vesicle And Their Stability, Anjana Khanal

Theses and Dissertations

This thesis introduces a microfluidic method to generate monodisperse water-in-oil-in water double emulsions. The microfluidic method is able to produce double emulsions with high degree of controllability and flexibility on size and number of droplets. We demonstrate this by producing double emulsions containing 1-8 inner water droplets and studied their dewetting phenomena to lipid bilayer scaffold. Our study shows that for the dewetting phenomenon to occur the oil must be volatile, polar and should make low contact angle with the involved interfaces. The chloroform shows self-emulsification behavior in presence of surfactant F127. The topological droplets formation with multiple compartments is …

Establishing A Mechanistic Link Between Disturbed Flow And Aneurysm Formation In A 3d Cerebral Bifurcation Model, Nesrine Bouhrira

Theses and Dissertations

The effect of disturbed flow profiles on the endothelium have been studied extensively in systemic vasculature, but less is known about the response of the blood-brain barrier (BBB) to these flow regimes. Here we investigate the effect of steady and pulsatile disturbed flow on the integrity of the BBB using a three-dimensional, perfusable bifurcation model consisting of a co-culture of endothelial cells with mural and glial cells. Experimental flow patterns predicted by computational fluid dynamics mimic in vivo flow regimes, specifically the presence of a recirculation zone immediately downstream of the bifurcation reveal periodic changes in the instantaneous shear stress …

Discrete Element Modeling Of Hydrogel Extrusion, Rohit Boddu

Theses and Dissertations

Hydrogels are widely used in extrusion bioprinting as bioinks. Understanding how the hydrogel microstructure affects the bioprinting process aids researchers in predicting the behavior of biological components. Current experimental tools are unable to measure internal forces and microstructure variations during the bioprinting process. In this work, discrete element modeling was used to study the internal interactions and the elastic deformation of the molecular chains within hydrogel networks during the extrusion process. Two-dimensional models of hydrogel extrusions were created in Particle Flow Code (PFC; Itasca Co., Minneapolis, MN). For our model's calibration, hydrogel compression testing was used in which a cluster …

Investigation Of The Load-Induced Cracking And Rutting Performance Of Specialty Hot Mix Asphalt Overlay Mixtures, Andrae Anthony Francois

Theses and Dissertations

This study was initiated with the aim of investigating the cracking performance, rutting performance, and cost effectiveness of specialty and composite HMA mixtures utilized in New Jersey to rehabilitate deteriorated rigid pavements. As such, four, plant-produced, specialty HMA overlay mixtures currently used in New Jersey were evaluated in this study. These overlay mixtures included: a dense-graded, 9.5-SP mixture, a gap-graded, 12.5-SMA mixture, a dense graded, 4.75-HPTO mixture, and a uniformly graded, 4.75-BRIC mixture. The 9.5-SP, 12.5-SMA, and 4.75-HPTO mixtures were produced using PG 76-22 binder while the 4.75-BRIC was contained a PG 70-28 binder. The laboratory cracking and rutting performance …

Enhanced Interest Aware Peoplerank For Opportunistic Mobile Social Networks, Yosra Saad Shahin

Theses and Dissertations

Network infrastructures are being continuously challenged by increased demand, resource-hungry applications, and at times of crisis when people need to work from homes such as the current Covid-19 epidemic situation, where most of the countries applied partial or complete lockdown and most of the people worked from home. Opportunistic Mobile Social Networks (OMSN) prove to be a great candidate to support existing network infrastructures. However, OMSNs have copious challenges comprising frequent disconnections and long delays. we aim to enhance the performance of OMSNs including delivery ratio and delay. We build upon an interest-aware social forwarding algorithm, namely Interest Aware PeopleRank …

Reinforcement Learning-Based Access Schemes In Cognitive Radio Networks, Ehab Maged Elguindy

Theses and Dissertations

In this thesis, we propose different MAC protocols based on three Reinforcement Learning (RL) approaches, namely Q-Learning, Deep Q-Network (DQN), and Deep Deterministic Policy Gradient (DDPG). We exploit the primary user (PU) feedback, in the form of ARQ and CQI bits, to enhance the performance of the secondary user (SU) MAC protocols. Exploiting the PU feedback information can be applied on the top of any SU sensing-based MAC protocol. Our proposed model relies on two main pillars, namely, an infinite-state Partially Observable Markov Decision Process (POMDP) to model the system dynamics besides a queuing-theoretic model for the PU queue; the …

Multi-Skilled Labor Optimization With Partial Allocation Of Resources, Amira Saleh

Theses and Dissertations

The current practice of labor allocation in construction schedules assumes single-skilled workforce; meaning that each worker is assumed to be skilled in only one trade. In such practice, at any instance in the project lifecycle, some of the workforce become idle waiting for other labor types to complete their work. Traditionally, companies may relocate idle workers to other projects and return them back to their original project when needed again. This complicates the resource management process and is not often performed successfully, leading to schedule and cost overruns. Alternatively, project managers may keep the idle workforce at their projects because …

A Computational Study Of Cocrfeniti High Entropy Alloys: Phase Diagrams, Thermodynamics, And Mechanical Properties From Calphad And First Principles, Geraldine Anis

Theses and Dissertations

High entropy alloys (HEAs) are multi-component alloys, which are often defined as those consisting of at least 5 principal elements with concentrations ranging between 5 and 35 atomic weight percent (at.%). Since their introduction by Yeh et al. and Cantor et al. in 2004, HEAs have been found to possess many important properties and have become prime candidates for several high-performance applications such as high-temperature and biomedical applications. Despite their multi-principal element nature, many HEAs favor the formation of solid solution phases as opposed to the intermetallic phases expected for such systems. This was originally only attributed to their high …

An Optimized Lte-Based Technique For Drone Base Station 3d Placement And Resource Allocation In Delay-Sensitive M2m Networks, Ahmed Fahim

Theses and Dissertations

The deployment of drone-mounted communication systems has received increasing interest and attention recently as it allows significant improvement to the network access capacity and coverage. Many applications can benefit from such deployments in particular machine-to-machine (M2M) communications. Drones are expected to facilitate extending wireless network access for both human users and the smart machine-type-communication devices (MTCDs) that have strict and diverse quality of service (QoS) requirements. In this thesis, we propose an optimal solution for the dynamic placement of an LTE drone-mounted base station to maximize the coverage of MTCDs deployed over a large geographical area in disaster situations or …

Nanoengineered Materials For Energy Conversion & Storage Applications: A Density Functional Theory Study, Ahmed Biby

Theses and Dissertations

The conventional approach for the development of novel materials has become long relative to the desired product development cycle. Thus, the sluggish pace of the development of materials within the conventional approach hinders the rapid transformation of the scientific outcomes into useful technological products. To this end, the field of hierarchical materials informatics evolved to bridge this gap. In this field, the multiscale material internal structure is considered the starting point and the core of this approach. This being said, the density functional theory (DFT) was used to generate useful materials data for the advancement of the hierarchical materials data-bases …

Investigating The Performance Of Hydroponic Nutrient Solutions As Potential Draw Solutions For Fertilizer Drawn Forward Osmosis, Mohamed Bassiouny Abu Qersh

Theses and Dissertations

This research project aims at investigating the performance of hydroponic nutrient solutions as draw solutions for desalination using the fertilizer drawn forward osmosis (FDFO) process. Six different lettuce and leafy greens hydroponic nutrient stock solutions were prepared according to the literature and used in this study and tested on a bench-scale forward osmosis unit as draw solutions for the process. The feed solutions for the process was de-ionized water mixed with Sodium Chloride in different concentrations to represent different salinities of brackish groundwater. The draw efficiency of each solution was measured based on water flux, reverse solute flux, water recovery, …

A Web-Based Change Control Management Toolkit For Lump-Sum Turnkey Contractors: Transformation To Third Generation, Ahmed Omran

Theses and Dissertations

Project deviations and changes are one of the key common particulars encountered in the Construction industry. Project changes can occur in different forms, may impact different pillars of the project, and can be caused due to the existence of various underlying factors. Mismanaging or lack of controlling these changes is one of the key contributing factors leading to project hardships. Contractors incur profit erosion, scope creep, and time slippages mainly by failing to have an effective project change management system enforced within its project execution philosophy. Such adversity is amplified for contractors engaging in lump-sum turnkey “LSTK” projects. Contractors encounter …

Molecular Dynamic Simulation Of Protein Devices And The Parameterization Of Azides And Alkynes For Use In Unnatural Amino Acid Models, Addison Kyle Smith

Theses and Dissertations

Proteins that have been modified by attaching them to a surface or to a polyethylene glycol (PEG) molecule can see many uses in therapeutics and diagnostics -- these unique proteins are called protein devices. Current techniques can perform these functionalizations at a specific residue on the protein, but what remains is identifying what happens to protein structure when mutated, and where to perform the attachment. Both of these issues can be examined using molecular dynamic (MD) simulations. Currently, simulations of the unnatural amino acid (uAA) mutations necessary for protein device functionalization cannot be executed, and full-protein screens of all possible …

Development Of A Hurricane Recovery Function And Resilience Model For Single-Family Residential Homes, Uriel Robert Donald Clark

Theses and Dissertations

The resilience of communities, infrastructure, and the environment in the face of hurricanes has increasingly become of public interest in the wake of recent natural disasters and environmental activism. Previous methodologies have attempted to quantify resilience for various structures and scenarios. Many studies have primarily investigated the robustness of critical infrastructure (e.g., bridges, emergency facilities, and water systems) which are essential to the function of a community. However, few studies have applied this approach to individual residential buildings. Therefore, this research aimed to adapt the most recent recovery functions developed for residential homes by considering measurable factors that are known …

Scalable Fabrication Of Post-Drawn Bio-Based And Petroleum-Based Nanofibers With Tunable Fiber Alignment, Morphology, And Mechanical Properties Via An Automated Track Approach, Dave Jao

Theses and Dissertations

We propose to expand nanomanufacturing capabilities and develop processing methods to produce advanced nanofiber materials with enhanced macromolecular and functional properties. Over the past decade, there has been a tremendous increase in the demand for polymeric nanofibers, which are promising candidates for a wide range of technological applications, including tissue engineering, protective clothing, filtration/absorption materials, and sensors/electronic devices, batteries/energy harvest, and fiber-reinforced composites [1]. However, the accessibility of nanofiber materials is limited because it is impossible to produce polymer nanofibers using conventional techniques. Typically, conventional polymer fibers are manufactured by mechanical extrusion with a secondary post-drawing step that stretches the …

Using System Dynamics To Study The Effect Of Change Orders On Labor Productivity, Shrouk Gharib

Theses and Dissertations

Change orders in construction projects lead to numerous negative impacts, including loss of labor productivity, delays, and cost overruns. Owners and contractors are usually in disagreement when it comes to allocating the extent of responsibilities with respect to the resulting overruns. Each party tries to hold the other party fully responsible for such overruns through a series of claims and disputes. Several delay analysis techniques have been developed to aid in settling such disputes, however, they do not fully grasp the rippled impacts of change orders and do not assist parties in reaching consensus when it comes to finding the …

Effects Of Static And Dynamic Thermal Gradients In Gas Chromatography, Samuel Avila

Theses and Dissertations

Gas chromatography (GC) is an analytical chemistry tool used to determine the chemical composition of a gas sample by separating sample analytes as they travel through a GC column. Recent efforts have been made to understand and control gas chromatography separations with a negative thermal gradient on the column. The present work presents results from thermal gradient GC separations on two GC columns in different configurations (serpentine and radial) in a stainless-steel plate. Methods to fabricate the GC systems capable of isothermal, temperature programmed and thermal gradient separations are presented. Isothermal experimental data from the serpentine column were used to …

Analizimi I Efiqiences Së Transformatorëve Në Sistemin Elektroenergjetik Të Kosovës, Flamur Zeka

Theses and Dissertations

Analizimi i efiqiencës së transformatorëve në sistemin elektroenergjetik të kosovës, na bënë të kuptojmë se me analizimin e rrjetit dhe me analizën e transoframtorëve në kosovë gjendja e efiqiencës nuk është mjaftë e mire, problemi qëndron të amortizimi i trafove, vjetërsia e tyre, kapaciteti i vogel ndaj kërkesave të konsumatorëve dhe mundësia e zavendësimit me trafo të reja. Instalimi i transformatorëve me kapacaitet dhe efiqienc më të madhe, ndër të tjera kryesore është edhe ta analizojmë koston e cila duhet për ta bërë zavendësimin e një tranformatori të vjeter me të ri i cili i plotësonë standardet Europiane.

Në temën …

Menaxhimi I Planit Dinamik Per Objektin B+P+5, Sami Vataj

Theses and Dissertations

Menaxhimi i planit dinamik të projektit nënkupton procesin e udhëheqjes dhe planifikimit te aktiviteteve ndërtimore qe nevojiten për ta përfunduar një projekt ndërtimor.

Disiplina e ndërtimtarisë është profesion specifik sa i përket anës ekonomike dhe menaxheriale. Ndërtimtaria ka për synim ngritjen dhe rikonstruktimin e objekteve ndërtimore. Si veprimtari, ajo realizon produktin e caktuar, objektin ndërtimor-arkitektonik. Ndërtimtaria veqohet për shkak të aktiviteteve të shumta që nevojiten për arritjen e një rezultati brenda një afati kohor. Secili aktivitet si proces teknologjik ka kohëzgjatjen e tij.

Varësisht nga natyra e projektit kemi aktivitete që kryhen në vartësi nga aktivitetet tjera paraprake dhe aktivitete …

Computational Analysis And Prediction Of Intrinsic Disorder And Intrinsic Disorder Functions In Proteins, Akila I. Katuwawala

Theses and Dissertations

COMPUTATIONAL ANALYSIS AND PREDICTION OF INTRINSIC DISORDER AND INTRINSIC DISORDER FUNCTIONS IN PROTEINS

By Akila Imesha Katuwawala

A dissertation submitted in partial fulfillment of the requirements for the degree of Engineering, Doctor of Philosophy with a concentration in Computer Science at Virginia Commonwealth University.

Virginia Commonwealth University, 2021

Director: Lukasz Kurgan, Professor, Department of Computer Science

Proteins, as a fundamental class of biomolecules, have been studied from various perspectives over the past two centuries. The traditional notion is that proteins require fixed and stable three-dimensional structures to carry out biological functions. However, there is mounting evidence regarding a “special” class …

Nature-Inspired Material Strategies Towards Functional Devices, Sayantan Pradhan

Theses and Dissertations

Naturally sourced, renewable biomaterials possess outstanding advantages for a multitude of biomedical applications owing to their biodegradability, biocompatibility, and excellent mechanical properties. Of interest in this dissertation are silk (protein) and chitin (polysaccharide) biopolymers for the fabrication of functional biodevices. One of the major challenges restricting these materials beyond their traditional usage as passive substrate materials is the ability to combine them with high-resolution fabrication techniques. Initial research work is directed towards the fabrication of micropatterned, flexible 2D substrates of silk fibroin and chitin using bench-top photolithographic techniques. Research is focused on imparting electrochemical properties to silk proteins using conducting …