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Full-Text Articles in Engineering
Trajectory Optimization Using Indirect Methods And Parametric Scramjet Cycle Analysis, Joseph Williams
Trajectory Optimization Using Indirect Methods And Parametric Scramjet Cycle Analysis, Joseph Williams
Open Access Theses
This study investigates the solution of time sensitive regional strike trajectories for hypersonic missiles. This minimum time trajectory is suspected to be best performed by scramjet powered hypersonic missiles which creates strong coupled interaction between the flight dynamics and the performance of the engine. Comprehensive engine models are necessary to gain better insight into scramjet propulsion. Separately, robust and comprehensive trajectory analysis provides references for vehicles to fly along. However, additional observation and understanding is obtained by integrating the propulsion model inside the trajectory framework. Going beyond curve fitted thrusting models, an integrated scramjet cycle analysis offers rapid trade studies …
Design Of An Asymmetric Reluctance Machine For A Generator Application, Bryan David Marquet
Design Of An Asymmetric Reluctance Machine For A Generator Application, Bryan David Marquet
Open Access Theses
This work compares an Asymmetric Reluctance Machine (ARM) to a Uniform air Gap Reluctance Machine (UGRM) for a generator application. The ARM employs an asymmetric rotor pole to increase machine performance, specifically increasing torque density. A multi-objective optimization is employed to minimize mass and loss subject to design constraints. Two machines are compared in terms of their Pareto-optimal fronts.
Optimization Of Wireless Power Networks For Biomedical Applications, Kyle A. Thackston
Optimization Of Wireless Power Networks For Biomedical Applications, Kyle A. Thackston
Open Access Theses
Successful physiological integration of electronics will open the doors to new methods of treatment and diagnoses. One of the key challenges of this integration is designing devices as small as possible while still maintaining high functionality, such as bio-signal recording, processing, telemetry, and stimulation. Wireless power transfer (WPT) can help shrink a device’s footprint by removing the need for bulky batteries. While many modalities of WPT exist for biomedical applications, the optimal power transfer efficiency (PTE) is seldom achieved due to improper impedance matching. Existing methods for determining the optimal impedance matching conditions tend to be application specific and make …
Modeling Preventive Maintenance In Complex Systems, Jessica Rivas
Modeling Preventive Maintenance In Complex Systems, Jessica Rivas
Open Access Theses
This thesis presents an explicit consideration of the impacts of modeling decisions on the resulting maintenance planning. Incomplete data is common in maintenance planning, but is rarely considered explicitly. Robust optimization aims to minimize the impact of uncertainty--here, in contrast, I show how its impact can be explicitly quantified. Doing so allows decision makers to determine whether it is worthwhile to invest in reducing uncertainty about the system or the effect of maintenance. The thesis consists of two parts. Part I uses a case study to show how incomplete data arises and how the data can be used to derive …
Finfet Device Optimization At 15nm For Near-Threshold Operation, Jolene Singh
Finfet Device Optimization At 15nm For Near-Threshold Operation, Jolene Singh
Open Access Theses
Much of the current research in the electronic industry focuses on reducing power consumption of digital circuits. Towards the same many attempts are being made to reduce the operating voltage of the circuits. It has been shown through device and circuit analysis that a circuit consumes minimum energy when operated near threshold voltage. In this thesis I vary device parameters and study their effects on energy consumption and delay of the device for the two regions of operation - superthreshold and near-threshold, using LUTs of IV and CV characteristics, verilogA and hSpice. Finally, device parameters are obtained for an optimum …
Time Domain Simulation Of Novel Photovoltaic Materials, Haejun Chung
Time Domain Simulation Of Novel Photovoltaic Materials, Haejun Chung
Open Access Theses
Thin-film silicon-based solar cells have operated far from the Shockley- Queisser limit in all experiments to date. Novel light-trapping structures, however, may help address this limitation. Finite-difference time domain simulation methods offer the potential to accurately determine the light-trapping potential of arbitrary dielectric structures, but suffer from materials modeling problems. In this thesis, existing dispersion models for novel photovoltaic materials will be reviewed, and a novel dispersion model, known as the quadratic complex rational function (QCRF), will be proposed. It has the advantage of accurately fitting experimental semiconductor dielectric values over a wide bandwidth in a numerically stable fashion. Applying …
A Mechanism Design Approach To Bandwidth Allocation In Tactical Data Networks, Ankur Mour
A Mechanism Design Approach To Bandwidth Allocation In Tactical Data Networks, Ankur Mour
Open Access Theses
The defense sector is undergoing a phase of rapid technological advancement, in the pursuit of its goal of information superiority. This goal depends on a large network of complex interconnected systems - sensors, weapons, soldiers - linked through a maze of heterogeneous networks. The sheer scale and size of these networks prompt behaviors that go beyond conglomerations of systems or `system-of-systems'. The lack of a central locus and disjointed, competing interests among large clusters of systems makes this characteristic of an Ultra Large Scale (ULS) system. These traits of ULS systems challenge and undermine the fundamental assumptions of today's software …