Engineering Commons^™

Design Of A Novel Wearable Ultrasound Vest For Autonomous Monitoring Of The Heart Using Machine Learning, Garrett G. Goodman

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As the population of older individuals increases worldwide, the number of people with cardiovascular issues and diseases is also increasing. The rate at which individuals in the United States of America and worldwide that succumb to Cardiovascular Disease (CVD) is rising as well. Approximately 2,303 Americans die to some form of CVD per day according to the American Heart Association. Furthermore, the Center for Disease Control and Prevention states that 647,000 Americans die yearly due to some form of CVD, which equates to one person every 37 seconds. Finally, the World Health Organization reports that the number one cause of …

As-Manufactured Modeling Of A Mistuned Turbine Engine Compressor Evaluated Against Experimental Approaches, Daniel L. Gillaugh

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As-manufactured rotors behave quite differently than nominal, as-designed rotors due to small geometric and material property deviations in the rotor, referred to as mistuning. Traditional integrally bladed rotor (IBR) modeling approaches assume each blade is identical. State-of-the-art IBR dynamic response predictions can be accomplished using asmanufactured models (AMM) generated via optical topography measurements and mesh morphing. As-manufactured models account for geometric deviations occurring through the machining process, material deviations and field wear, allowing each blade to respond differently. Rotor designs are intended to avoid resonance crossings throughout an engine’s operating range, but total avoidance is challenging. This has led to …

Using Cfd To Improve Off-Design Throughflow Analysis, Troy J. Lanchman

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In turbomachinery design, complex internal flows give rise to significant losses and blockage whose effects are difficult to properly analyze without detailed computational fluid dynamics (CFD) methods or experiments. In a typical design method, CFD is used in conjunction with simpler throughflow or cascade codes to hasten the process. However, the lesser physical accuracy of the design codes demands the inclusion of models to improve the accuracy of the throughflow codes. This thesis aims to use CFD data to generate improved loss and blockage models for a 2D compressor throughflow code by matching throughflow data to CFD data using optimizations. …

Rapidly Solving Physics-Based Models For Uncertainty Propagation In Nondestructive Evaluation, Matthew Ryan Cherry

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Recent research in extending nondestructive evaluation (NDE) methods toward damage and materials characterization has led to an emphasis on the development of physics-based forward models in NDE. Furthermore, a desire to quantify levels of uncertainty in NDE inspections, particularly in Air Force applications, has driven the need for quick solving surrogate models for the traditional forward models, which have largely focused on accurately capturing many aspects of the problem with little emphasis on computational effort. In the past 5 years, many different techniques for creating lower-fidelity, quickly solving models to be used in place of the expensive high fidelity simulations …

Imperfect Situation Analysis: Representing The Role Of Error And Uncertainty In Modeling, Simulation And Analysis, Victor Eaton Middleton

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Much of traditional modeling, simulation and analysis (MS&A) is supported by engineering models - deterministic, Newtonian physics-based representations of closed systems. Such approaches are not well-suited to represent the intricacies of human behavior. This research advocates and seeks to articulate the concept of a more human- centric approach to MS& A, one that better represents decision-making and other cognitive aspects of human behavior as well as it does physical activity.

It starts with a view of individuals and groups as complex adaptive systems, which are best represented using agent-based modeling. Representation of human behavior through intelligent agents incorporates models of …

A Theoretical Adaptive Autonomy Model: Real-Time Physiological Assessment Of Cognitive Workload, Dakota C. Evans

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Increases in modern-day system complexity, has led for a need to improve human performance and the interaction between the two. Three objectives: (1) to investigate physiological measures as indicators of cognitive workload, (2) to assess cognitive workload during human interaction with different autonomy levels, and (3) to develop a theoretical model for an adaptive autonomous system that changes with real-time cognitive workload measures were addressed. This effort seeks to improve human computer interaction by providing the human with the acceptable level of computer automation based on real-time cognitive state. Two experiments involved collection of measures of subject physiology, subjective survey …

Effects Of Large-Scale Transient Loading And Waste Heat Rejection On A Three Stream Variable Cycle Engine, Michael William Corbett

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The objective of the research presented in this document was to gain an understanding of the feasibility of extracting large amounts of transient shaft power from a variable cycle engine and to reject waste heat into the third stream bypass duct. This first required the development of a transient engine and controller simulation. After performing basic verification of the model, such as ensuring conservation of mass, tests were run for three missions using a low-efficiency periodic load which both required shaft power and created low quality waste heat. The waste heat generated by that load was lifted by a cooling …

Aircraft Gearbox Dynamics Subject To Electromechanical Actuator Regenerative Energy Flow, Matthew S. Rutledge

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To increase reliability and efficiency, standard aircraft components are being replaced with more electric subsystems aimed to reduce weight, conserve space, and improve energy management. One application of this process replaces standard hydraulic actuators used in flap or aileron movements with electromechanical actuators powered by an external generator. During different types of return movements, the electromechanical actuator will produce regenerative power that flows back through the generator and pulses into the engine-gearbox subsystem. The regenerative power, defined by characteristic amplitude, frequency, and other pulse attributes, coupled with the driving force produced by the engine may dramatically impact the performance and …

High Voltage Dc Converter Systems Modeling, Simulation And Analysis, Manish A. Dalal

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The thesis provides insights into important modeling techniques to model the converter system, machine design, control and power stages and integration of the various sub systems to simulate the system level performance. This innovative modeling and simulation project is very relevant to optimizing the system performance, designing the sub circuits, components selection, predicting the system stability and impulse responses. The thesis presents modeling and simulation of three different 270VDC converter systems and comparing their performances against each other. The 270VDC converter system accepts either Generator 3-phase AC voltages or fixed three voltage source followed by single or dual converter stages …

An Initial Methodology For The Definition And Implementation Of Unmanned Aerial Vehicle Agent Behaviors, William Eric Marsh

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In many current agent-based modeling systems, it is difficult for a domain-expert user to define and implement agent behaviors without possessing extensive programming knowledge. MUAVES is an existing simulation environment that serves as a research testbed for examining command and control issues with unmanned aerial vehicle (UAV) systems containing many vehicle agents. In its previous form, defining agent behaviors required knowledge of the C# programming language that some MUAVES users did not have. This thesis presents a new methodology for the definition and implementation of UAV agent behaviors in MUAVES. The new methodology is based on diagramming an agent's controller …

Modeling And Simulation Of A Microturbine Generator To Be Coupled With A Molten Carbonate Fuel Cell For Distributed Generation, Karleine M. Justice

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Distributed generation is desired when the individual energy requirements ranging from 25-75 kW of office buildings, restaurants, hospitals and apartments can not be met by the current electric utility grid. Microturbine generators as stand alone power generation systems have been designed to meet these requirements. For power requirements up to 50 MW, hybrid fuel cell systems offer higher efficiency and lower levels of pollutant emissions with more advanced fuel energy savings than non-hybrid systems. The objective of this project is to develop a simulation of a microturbine generator as a stand alone power generation system to validate a microturbine generator …

Designing Computer Agents With Personality To Improve Human-Machine Collaboration In Complex Systems, Sasanka V. Prabhala

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The dynamic nature of complex systems and the overwhelming amount of data that must be handled by human operators requires the development of smart systems that augment human capabilities. For these systems human-agent collaboration is part of the system dynamic. Unfortunately the computer agent is not typically perceived by the human operator as a collaborative team member. This research addressed the key question of how to develop and evaluate computer agents with personality to enhance human-machine collaboration. To move towards this goal three research objectives were established: (1) develop agents with personality, (2) validate that humans perceive these agents as …