Engineering Commons^™

An Empirical Investigation Of The Behavior And Cognition Of Engineering Designers While Describing Domains Of Design Problems, John Kochenberger

Theses and Dissertations

This thesis presents a protocol study that examines the behavioral and cognitive patterns in human designers when they describe a problem domain of engineering interest through constructing concept maps. Understanding various design problem domains usually comes in design projects before the start of the formal design process and is crucial for discovering the pain points of given scenarios and identifying opportunities for creating value to improve them. Thus, this activity relies on the entrepreneurial aspects of engineering design that leads to identifying the right design problem to solve. While concept maps have been used to examine various research questions in …

Optimizing Repayment Strategies For Egyptian Construction Companies With Multiple Loans, Moataz Elkady

Theses and Dissertations

Optimizing Repayment Strategies for Egyptian Construction Companies with Multiple Loans is of utmost importance to efficiently allocate monthly income for loan repayment. The conventional practice of paying the minimum balance due each month leads to increased interest charges and prolonged repayment periods. In response, this research proposes a model for multiple loan repayment that considers the computational complexity involved.

The model is built on the foundation of mixed integer linear programming and aims to establish an optimal repayment schedule by minimizing the total cash required to repay the loans, prioritizing the repayment of loans before personal expenses. The implementation of …

Friction And Heat Transfer Modeling Of The Tool And Workpiece Interface In Friction Stir Welding Of Aa 6061-T6 For Improved Simulation Accuracy, Ryan Melander

Theses and Dissertations

Friction stir welding (FSW) is a solid-state joining process that offers advantages over traditional fusion welding. The amount of heat generated during a FSW process greatly influences the final properties of the weld. The heat is generated through two main mechanisms: friction and plastic deformation, with friction being the larger contributor in a FSW process. There is a need to develop better predictive models of the heat generation and heat transfer in FSW. Almost all models seen in the literature validate temperature predictions on only one side of the tool/workpiece interface, thus ignoring possible inaccuracy that comes from incorrect partitioning …

Integration Of Insoluble And Soluble Dopants Into Steel Using Laser Powder Bed Fusion, Mckay Goodman Sperry

Theses and Dissertations

Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing (AM) method whereby complex parts can be built to near net geometry in an automated environment. Parts formed by LPBF have excellent properties and require little post-processing. While LPBF allows for creative designs to reduce weight and part count by integrating sub-components of assemblies, designers are limited to one material within any LPBF print. Although various materials can be used in LPBF, metals are of special interest to many industrial customers due to their high strength and toughness. The metals commonly used for LPBF include iron, aluminum, and titanium alloys. These …

Development Of Attack Resistant Cybersecurity Framework For Digital Health Systems, Sridevi A

Theses and Dissertations

The emerging cyber landscape demands the data to be protected by CIA triad which comprises Confidentiality, Integrity and Availability(CIA). For the swift diagnosis process, a standard patient data representation in the form of EHR (Electronic Health Record) plays a significant role. There exists a necessity to protect this EHR through the information security mechanisms namely encryption, watermarking and intrusion detection system for ensuring application and network layer security. Implementation of medical data protection solution on a reconfigurable hardware platform can further strengthen EHR security. This research work effectively achieves the CIA triad for healthcare cybersecurity at data, application and network …

Detecting Lumbar Muscle Fatigue Using Nanocomposite Strain Gauges, Darci Ann Billmire

Theses and Dissertations

Introduction: Muscle fatigue can contribute to acute flare-ups of lower back pain with associated consequences such as pain, disability, lost work time, increased healthcare utilization, and increased opioid use and potential abuse. The SPINE Sense system is a wearable device with 16 high deflection nanocomposite strain gauge sensors on kinesiology tape which is adhered to the skin of the lower back. This device is used to correlate lumbar skin strains with the motion of the lumbar vertebrae and to phenotype lumbar spine motion. In this work it was hypothesized that the SPINE Sense device can be used to detect differences …

On Algorithmic Design Methodologies, Heterogenous Rfsoc/Gpu Beamformers, And Cryogenic Antenna Efficiency Evaluation For Phased Array Receivers In Radio Astronomy, Mitchell C. Burnett

Theses and Dissertations

Modern radio astronomy’s demand for high sensitivity and wide fields of view is met through innovations that reduce receiver system noise temperatures and integrate technology supporting parallel processing and larger instantaneous bandwidths. The advanced L-band phased array camera for astronomy (ALPACA) is a fully cryogenic 69 dual-polarized dipole PAF and digital beamformer back end for the Green Bank Telescope. This instrument will form 40 dual-polarized beams yielding a 0.35 sq. deg field of view on the sky with a 305.2 MHz processing bandwidth. The target system noise temperature is 27 K. A structured technique to map critically sampled and oversampled …

Refill Friction Stir Fastener Repair In Aa7050-T7451, Andrew John Curtis

Theses and Dissertations

The majority of Refill Friction Stir Spot Welding (RFSSW) is used to join two materials together oriented in a lap joint configuration. In this study, RFSSW was investigated and tested using an unconventional configuration setup, a hole/plug insertion approach. RFSSW was tested as a means of repairing a cracked rivet hole due to excessive use conditions. This was done by inserting a plug into a hole and using the RFSSW process to bond the plug to the base material. Machine and tool limits were investigated to determine if a refilled plug repair was possible and if complete mixing between plug/hole …

Cesium Voltilization In Lif-Bef2: Predicting Release In The Event Of Fhr Fuel Failure, Johnny Hedrick Williams

Theses and Dissertations

This work demonstrates how ICP-MS can be employed to evaluate cesium volatilization from LiF-BeF2 (Flibe) salt with ab initio molecular dynamics studies used as corroborating data to better understand cesium behavior. Using mixtures of Flibe with 2 mol% CsF, it was found that cesium was stable within the salt melt at temperatures between 500-650°C over a time span of 8 hours. At 800°C, cesium vaporized from the salt at a rate of 0.83% / hr with a mass flux of 0.0023 g Cs / cm2hr. The atomistic modeling results show poor solvation of Cs at 500°C and 800°C, with stability …

Securing Wireless Communication Via Information-Theoretic Approaches: Innovative Schemes And Code Design Techniques, Morteza Shoushtari

Theses and Dissertations

Historically, wireless communication security solutions have heavily relied on computational methods, such as cryptographic algorithms implemented in the upper layers of the network stack. Although these methods have been effective, they may not always be sufficient to address all security threats. An alternative approach for achieving secure communication is the physical layer security approach, which utilizes the physical properties of the communication channel through appropriate coding and signal processing. The goal of this Ph.D. dissertation is to leverage the foundations of information-theoretic security to develop innovative and secure schemes, as well as code design techniques, that can enhance security and …

Stochastic Worst-Case Test Vectors For Asic Devices In Single Event Environment, Mostafa Hemeda

Theses and Dissertations

Charged particles and energetic particles can impact the integrated circuit, referred to as single event effects (SEE). Nuclear reactors and space radiation can produce these particles. These effects can negatively affect the reliability and performance of electronics. When SEE occurs, a transient current is created, which can cause electronic devices to have incorrect outputs and ultimately fail. As a result, ensuring the reliability of ASIC circuits is a significant concern.

This thesis discusses the different fault types, then discuss the soft error and, in particular, the Single Event Transient (SET) and its causes and models. Then, this thesis proposes a …

User Profiling Through Zero-Permission Sensors And Machine Learning, Ahmed Elhussiny

Theses and Dissertations

With the rise of mobile and pervasive computing, users are often ingesting content on the go. Services are constantly competing for attention in a very crowded field. It is only logical that users would allot their attention to the services that are most likely to adapt to their needs and interests. This matter becomes trivial when users create accounts and explicitly inform the services of their demographics and interests. Unfortunately, due to privacy and security concerns, and due to the fast nature of computing today, users see the registration process as an unnecessary hurdle to bypass, effectively refusing to provide …

Resources Based Planning Framework For Infrastructure Maintenance And Rehabilitation Projects, Heba Gad

Theses and Dissertations

Infrastructure maintenance and rehabilitation projects involve activities scattered over a large geographical area (e.g., scattered road segments maintenance, telecom towers maintenance program, etc.). Planning such projects require a resource-based approach that accounts for the implications of resource mobility between activities’ locations in terms of time & cost. Existing scheduling techniques fall short of addressing the unique challenges of the scattered nature of these projects in combination with organization's limited resources availability. To address this need, this research presents a resources-based planning framework for infrastructure maintenance and rehabilitation scattered projects with the objective of enhancing resources utilization achieving time and cost …

Spatial Autocorrelation Analysis For Construction Sites, Raghda Moharram

Theses and Dissertations

This study investigates the usefulness of spatial autocorrelation analysis in construction sites. The objective is to provide construction managers with insights into the site's performance, identify potential areas for improvement, and ultimately lead to cost and time savings and improved project quality. To achieve this objective, the study identifies significant spatial autocorrelation variables for various applications in construction and analyzes their impact on the site's efficiency and potential problems.

The potential applications where spatial autocorrelation analysis could be useful were identified, including schedules, progress, earned value measures, safety incidents, workers' densities, equipment densities, energy expenditure, and quality non-conformity. A framework …

Influence Of Organizational Culture And Leadership Style On Disputes In Construction Projects – A Contractor’S Perspective, Omneya Nader Mekhaimer

Theses and Dissertations

Over the recent decades, studies on organizational culture and leadership practices have gained global attention across business management literature given their implicit influence on the organization’s success. However, very few studies tackled these practices in the construction industry research especially in Egypt. Unlike other industries, the construction industry is known to be a complex, dynamic, and adversarial industry sector due to its project-oriented nature where various stakeholders are involved and each have their own objectives. Consequently, construction disputes are inevitable to occur whereby previous studies revealed that the level of disputes have propagated throughout the years.

This research aims to …

A Novel Approach Using Integrated Greywater Treatment System Applying Net Zero Wastewater Concept For Sustainable Urban Communities, Mianda Khattab

Theses and Dissertations

We are blessed with endless resources that are naturally existing in our world and we fully rely-on without envisioning the bigger picture of what would happen if these resources came to an end, or how can we even ensure sustainable lives by regenerating or reusing or utilizing the naturally existing resources? The surrounding ecosystem, the land we live on, the air we breathe, the water we drink and use for cooking, laundry, shower, irrigation, and many other usages are examples of the resources that we, as global users, are taking for granted.

It is a common knowledge that we are …

Evaluating The Impact Of Oxidation On Moisture Resistance Of Asphalt Components And Mixtures, Ahmad Alfalah

Theses and Dissertations

This study investigated the effects of asphalt oxidation and testing temperature on moisture damage in asphalt mixtures, using AASHTO T283 and Surface Free Energy (SFE) testing. The study assessed the impact of three asphalt binder grades (PG 64-22, PG 76-22, and PG 52-34) and three test temperatures (ALT, AIT, and CIT) on the susceptibility to moisture damage. Additionally, three oxidation levels (OTC, STOC, and LTOC) were evaluated to determine the optimal level of oxidation and testing temperature for AASHTO T283 to detect moisture damage. Load-displacement curve parameters and IDEAL-CT were analyzed to better understand the effects of oxidation and moisture …

Role Of Defect Type In Optimizing Photoelectrochemical Hydrogen Production Catalysts, Mohamed Mahrous

Theses and Dissertations

The search for new energy sources has become a global challenge due to the increasing demand for energy and the negative impact of traditional energy sources on the environment. The photoelectrochemical water splitting has emerged as a promising alternative source for producing hydrogen, which can be used as a clean fuel. However, it is necessary to tailor the properties of the light-active material that will be used to absorb sunlight and split water. This research project aimed at providing detailed insights into the effect of varying the type and concentration of defects on the optical and electronic properties of diamond …

Additive Manufacturing Of Stretchable Strain Sensors: Fabrication, Optimization And Application, John Nady Shihat Bastawrous

Theses and Dissertations

In this project, a novel strain sensor design is fabricated employing different additive manufacturing techniques. The spring sensor's primary material is PLA-Like resin with a nanocomposite encapsulation layer as the functional material. The main principle of Straining the sensors results in a change in resistivity as the distances among the conductive carbon particles change according to the strain applied.

Sensor fabrication consists of two parts: spring manufacturing and development of nanocomposite encapsulation The nanocomposite matrix is developed through the dispersion of Graphene and Carbon nanotubes in Thermoplastic Polyurethane through sonication and magnetic hotplate stirring. While the spring itself is manufactured …

Chemical And Polymer Characterization Of The Potential Modes Of Degradation Of An Injectable Nucleus Pulposus Replacement Device, Antonio G. Abbondandolo

Theses and Dissertations

HYDRAFIL™ is a poly(vinyl alcohol)/poly(ethylene glycol)-based hydrogel nucleus pulposus replacement device that is injected in situ and has demonstrated efficacy in lowering the prevalence and pain associated with back. In this work, we developed a method to analyze HYDRAFIL™ polymer composition using (TGA) and characterized intermolecular bonding interactions within the hydrogel through (FTIR). To function as a permanent implant for nucleus pulposus replacement, HYDRAFIL™ must be stable when exposed to a multitude of degradation pathways, namely, thermal, chemical, and mechanical. We subjected HYDRAFIL™ to accelerated thermal and chemical degradation pathways and described compositional, physical and chemical property changes using a …

Evaluating Parameter Uncertainty In Transportation Demand Models, Natalie Mae Gray

Theses and Dissertations

The inherent uncertainty in travel forecasting models -- arising from errors in input data, parameter estimation, or model formulation -- is receiving increasing attention from the scholarly and practicing community. In this research, we investigate the variance in forecasted traffic volumes resulting from varying the mode and destination choice parameters in an advanced trip-based travel demand model. Using Latin hypercube sampling to construct several hundred combinations of parameters across the plausible parameter space, we introduce substantial changes to mode and destination choice logsums and probabilities. However, the aggregate effects of of these changes on forecasted traffic volumes is small, with …

Evaluating Effects Of Urban Growth Within The Greater Salt Lake Area On Local Meteorological Conditions Using Urban Canopy Modeling, Corey L. Smithson

Theses and Dissertations

The increasing urbanization of the greater Salt Lake City area (GSLA) has contributed to the development of an urban canopy over this area. This canopy refers to the effects of building profiles, varying land surface properties and anthropogenic heating on local meteorological conditions including temperature, humidity, and wind velocity. Urban Canopy Models (UCMs) can be used to represent these characteristics on a mesoscale without needing to develop models accounting for effects of individual buildings. One method used to classify urban areas are Local Climate Zones (LCZs), which assign different properties to different types of urban areas. A baseline model that …

Predictive Modeling The Impact Of Engineered Products In Dynamic Sociotechnical Systems: An Agent-Based Approach, Christopher S. Mabey

Theses and Dissertations

The impact of engineered products is a topic of increasing concern in society. The impact of a product can fall into the categories of economic, environmental, or social impact; the last category is defined as the effect of a product on the daily lives of people. Design teams lack sufficient tools to help improve the impact of products and understand the impact of products at scale in society. This dissertation aims to provide insight and methods for improving the social, environmental, and economic impact of engineered products. The majority of the research focuses on the prediction of product impacts on …

Evaluating The Feasibility Of Bioenergy Production From Single And Mixed Beverage Waste And Sewage Sludge Through An Integrated Hydrothermal Liquefaction-Anaerobic Digestion System, Oluwayinka Michael Adedeji

Theses and Dissertations

Beverage waste and sewage sludge are two of the most generated waste-based biomasses. Recent interest in the hydrothermal liquefaction (HTL) of these wastes pointed to the generation of a byproduct of high dissolved organic carbon [also called aqueous co-product (ACP)]. However, ACP is being discarded which not only increases the environmental footprints of the HTL process but also results in reduced bioenergy potential. Hence, anaerobic digestion (AD) is touted as an effective utilization process of ACP for further bioenergy recovery. This study evaluated the feasibility of producing bioenergy (biocrude and biomethane) from the combination of beverage waste and sewage sludge …

The Use Of Point Cloud Data To Support Concrete Bridge Deck Condition Assessment, Issa Nidal Al Shaini

Theses and Dissertations

Bridge deck condition assessments are typically conducted through visual physical inspections, utilizing traditional contact sensors for Non-Destructive Evaluation techniques such as hammer Sounding and chain dragging which require the expertise of trained inspectors. However, the accuracy of these inspections is limited by the level of deterioration of the bridge deck, as the ability of the inspectors is proportional to the apparent level of damage. This study aims to improve the accuracy of bridge deck inspection processes by utilizing non-destructive evaluation techniques, including the analysis of point cloud data gathered via Light Detection and Ranging (LiDAR) as a geometry-capturing tool. The …

Design Of A Transparent Cryogenic Silicon Carbide Probe Card With Tungsten Probe Tips, Ryan Beazer

Theses and Dissertations

DoD EO/IR applications continue to push imaging technology. Next generation advances require new material systems, novel device structures, as well as the improvement and development of read out integrated circuits. The common methodology used to assess devices and materials is to process test chip structures and focal plane arrays. Test chips have advantages over focal plane arrays; such as, variable area and stand alone devices and can be measured as a function of bias and temperature; however, focal plane arrays are the heart of the imager, but are measured through the read out integrated circuits, which can add complexity to …

Adversary Aware Continual Learning, Muhammad Umer

Theses and Dissertations

Continual learning approaches are useful as they help the model to learn new information (classes) sequentially, while also retaining the previously acquired information (classes). However, these approaches are adversary agnostic, i.e., they do not consider the possibility of malicious attacks. In this dissertation, we have demonstrated that continual learning approaches are extremely vulnerable to the adversarial backdoor attacks, where an intelligent adversary can introduce small amount of misinformation to the model in the form of imperceptible backdoor pattern during training to cause deliberate forgetting of a specific class at test time. We then propose a novel defensive framework to counter …

A General Model For Noisy Labels In Machine Learning, Glenn Dawson

Theses and Dissertations

Machine learning is an ever-growing and increasingly pervasive presence in every-day life; we entrust these models, and systems built on these models, with some of our most sensitive information and security applications. However, for all of the trust that we place in these models, it is essential to recognize the fact that such models are simply reflections of the data and labels on which they are trained. To wit, if the data and labels are suspect, then so too must be the models that we rely on—yet, as larger and more comprehensive datasets become standard in contemporary machine learning, it …

Design And Analysis Of Asymmetric “String-Of-Pearls” Common Repeating-Ground-Track Satellite Constellations For Missions Requiring Regional Coverage, Nathaniel Choo

Theses and Dissertations

Satellite constellation design must balance many factors that emerge from multiple sources, including environmental hazards and competing mission objectives. The dynamic nature of space systems makes the problem of ‘optimal’ satellite constellation design even more challenging. Restricting satellite constellation designs to predefined geometric frameworks can alleviate many challenges associated with the design problem; however, it raises an important question: which geometric framework performs best for each mission set? This research leverages simulations, metaheuristics, and mathematical programming techniques to address this question for missions focusing on Earth-observation of one or more regions.

First, this research captures the current state of satellite …

Portfolio Optimization Using Value Focused Thinking, Tyler Martin

Theses and Dissertations

This thesis explores the application of Value Focused Thinking (VFT) and multi-objective portfolio optimization to create a well-aligned portfolio for an organization faced with over 50 alternatives and limited funding. A novel technique is proposed to develop an optimized portfolio based on VFT scores, utilizing heuristic approaches like evolutionary algorithms. The research outcomes include an optimized portfolio, the total value evaluation of alternatives, and a sensitivity analysis. The new approach outperforms the organization’s previous method, resulting in a portfolio that better addresses the organization’s core values and objectives, scoring 21.21% higher.