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Full-Text Articles in Engineering Science and Materials

Autonomous Mission Design In Extreme Orbit Environments, David Allen Surovik Jan 2016

Autonomous Mission Design In Extreme Orbit Environments, David Allen Surovik

Aerospace Engineering Sciences Graduate Theses & Dissertations

An algorithm for autonomous online mission design at asteroids, comets, and small moons is developed to meet the novel challenges of their complex non-Keplerian orbit environments, which render traditional methods inapplicable. The core concept of abstract reachability analysis, in which a set of impulsive maneuvering options is mapped onto a space of high-level mission outcomes, is applied to enable goal-oriented decision-making with robustness to uncertainty. These nuanced analyses are efficiently computed by utilizing a heuristic-based adaptive sampling scheme that either maximizes an objective function for autonomous planning or resolves details of interest for preliminary analysis and general study. Illustrative examples ...


Roll-To-Roll Atomic Layer Deposition Of Ultrabarriers, Alexander Yersak Jan 2016

Roll-To-Roll Atomic Layer Deposition Of Ultrabarriers, Alexander Yersak

Mechanical Engineering Graduate Theses & Dissertations

Atomic layer deposition (ALD) is a bottom-up, gas phase, thin film deposition technique based on sequential, self-limiting binary surface reactions. The precise sub-nanometer film thickness control and conformal nature of this process have led to various commercial applications of ALD. However, ALD films are most commonly deposited in batch processes at low pressures, which raises throughput and/or cost concerns for many otherwise promising applications. This problem can be solved by spatial ALD (S-ALD) which is a version of the ALD technique where the precursors are separated in space rather than time. We have demonstrated the first atmospheric pressure roll-to-roll ...