Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

PDF

Faculty Publications

Series

2016

Discipline
Institution
Keyword

Articles 91 - 94 of 94

Full-Text Articles in Engineering

Constructal Alkaline Membrane Fuel Cell (Amfc) Design, E. M. Sommer, J. V. C. Vargas, Lauber De Souza Martins, J. C. Ordonez Jan 2016

Constructal Alkaline Membrane Fuel Cell (Amfc) Design, E. M. Sommer, J. V. C. Vargas, Lauber De Souza Martins, J. C. Ordonez

Faculty Publications

This paper introduces a structured procedure to optimize the internal structure (relative sizes, spacing) and external shape (aspect ratios) of a single alkaline membrane fuel cell so that net power is maximized. The optimization of flow geometry is conducted for the smallest (elemental) level of a fuel cell stack, i.e., the single alkaline membrane fuel cell, which is modeled as a unidirectional flow system. The polarization curve, total and net power, and efficiency are obtained as functions of temperature, pressure, electrolyte solution concentration (KOH), geometry and operating parameters. The optimization is subjected to fixed total volume. There are two levels …


The Influence Of Operational Resources And Activities On Indirect Personnel Costs: A Multilevel Modeling Approach, Bradley C. Boehmke, Alan W. Johnson, Edward D. White, Jeffery D. Weir, Mark A. Gallagher Jan 2016

The Influence Of Operational Resources And Activities On Indirect Personnel Costs: A Multilevel Modeling Approach, Bradley C. Boehmke, Alan W. Johnson, Edward D. White, Jeffery D. Weir, Mark A. Gallagher

Faculty Publications

Indirect activities often represent an underemphasized, yet significant, contributing source of costs for organizations. In order to manage indirect costs, organizations must understand how these costs behave relative to changes in operational resources and activities. This is of particular interest to the Air Force and its sister services, because recent and projected reductions in defense spending are forcing reductions in their operational variables, and insufficient research exists to help them understand how this may influence indirect costs. Furthermore, although academic research on indirect costs has advanced the knowledge behind the modeling and behavior of indirect costs, significant gaps in the …


Unequal A Priori Probability Multiple Hypothesis Testing In Space Domain Awareness With The Space Surveillance Telescope, Tyler J. Hardy, Stephen C. Cain, Travis F. Blake Jan 2016

Unequal A Priori Probability Multiple Hypothesis Testing In Space Domain Awareness With The Space Surveillance Telescope, Tyler J. Hardy, Stephen C. Cain, Travis F. Blake

Faculty Publications

This paper investigates the ability to improve Space Domain Awareness (SDA) by increasing the number of detectable Resident Space Objects (RSOs) from space surveillance sensors. With matched filter based techniques, the expected impulse response, or Point Spread Function (PSF), is compared against the received data. In the situation where the images are spatially undersampled, the modeled PSF may not match the received data if the RSO does not fall in the center of the pixel. This aliasing can be accounted for with a Multiple Hypothesis Test (MHT). Previously, proposed MHTs have implemented a test with an equal a priori prior …


Landing Zone Determination For Autonomous Rotorcraft In Surveillance Applications, Timothy Mclain, Gary J. Ellingson, Justin Mackay Jan 2016

Landing Zone Determination For Autonomous Rotorcraft In Surveillance Applications, Timothy Mclain, Gary J. Ellingson, Justin Mackay

Faculty Publications

This paper presents an approach for finding possible landing sites for a rotorcraft from an inertially referenced point-cloud model of the environment. To identify potential landing sites that are suitably flat and level, a grid-based random sample consensus algorithm separates the terrain map into discrete areas for plane-fitting analysis. Landing sites are selected that satisfy constraints on flatness and levelness while optimizing the surveillance target’s visibility. Flight test results are presented from a small multirotor aircraft flying over a scale-model cityscape. Results from real-time landing-site experiments are presented and discussed.