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Institution

Wright-Patterson Air Force Base

OtherWright-Patterson AFB, Ohio, United States
About: Wright-Patterson Air Force Base is a other organization based out in Wright-Patterson AFB, Ohio, United States. It is known for research contribution in the topics: Laser & Mach number. The organization has 5817 authors who have published 9157 publications receiving 292559 citations. The organization is also known as: Wright-Patterson AFB & FFO.


Papers
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Proceedings ArticleDOI
14 Jun 2006
TL;DR: This work develops a low-complexity, accurate and reliable scheme to estimate the motion fields from UAV navigation videos, which allows us to accurately estimate ego-motion parameters of the UAV and refine (or correct) the motion measurements from other sensors.
Abstract: In this work, we explore various ideas and approaches to deal with the inherent uncertainty and image noise in motion analysis, and develop a low-complexity, accurate and reliable scheme to estimate the motion fields from UAV navigation videos. The motion field information allows us to accurately estimate ego-motion parameters of the UAV and refine (or correct) the motion measurements from other sensors. Based on the motion field information, we also compute the range map for objects in the scene. Once we have accurate knowledge about the vehicle motion and its navigation environment (range map), control and guidance laws can be designed to navigate the UAV between way points and avoid obstacles.

77 citations

Journal ArticleDOI
TL;DR: In this article, a microelectro-mechanical system-based experimental technique was used to measure thermal conductivity of freestanding ultra-thin films of amorphous silicon nitride (Si3N4) as a function of mechanical strain.
Abstract: We present a micro-electro-mechanical system-based experimental technique to measure thermal conductivity of freestanding ultra-thin films of amorphous silicon nitride (Si3N4) as a function of mechanical strain. Using a combination of infrared thermal micrography and multi-physics simulation, we measured thermal conductivity of 50 nm thick silicon nitride films to observe it decrease from 2.7 W (m K)?1?at zero strain to 0.34 W (m K)?1?at about 2.4% tensile strain. We propose that such strong strain?thermal conductivity coupling is due to strain effects on fraction?phonon interaction that decreases the dominant hopping mode conduction in the amorphous silicon nitride specimens.

77 citations

Journal ArticleDOI
TL;DR: A survey of the key aeroengine technology trends can be found in this paper, where the authors present a survey of recent advances in the field of aero-engine technology.
Abstract: Second only to the invention of an airplane by the Wright Brothers 100 years ago, the jet engine has revolutionized both military and civil aviation. We present a survey of the key aeroengine technology trends. Since 1939, engine thrust has increased over 100-fold and the (thrust/weight) ratio to 7. Whereas the early jet engines barely lasted for less than 10 hours, today's civil engines can stay on wings for up to 10,000 hours, and high-performance military engines can last several hundred hours. Advances in blade cooling technologies and high-temperature materials have permitted an increase in turbine inlet temperature from 1280 to 3200°F. Today, engine thermal efficiency is approaching 50%. Also, today's most powerful aeroengines already meet the International Civil Aviation Organization ultra-low gaseous and smoke requirements. Finally, civil and military technology is moving along the direction set by the versatile affordable advanced turbine engines (VAATE) propulsion capability goals. The spectacular achievements of the last century truly provide an outstanding start for many future achievements to come in the field of aeroengine technology, along the lines of the VAATE goals

77 citations

Journal ArticleDOI
TL;DR: It is suggested that inadequate venous return might not be the primary limitation of exercise capacity in this population of Fontan patients, and diastolic dysfunction and relatively excessive peak exercise pulmonary vascular resistance might be more important factors in Fontan exercise limitation.
Abstract: Fontan patients have a reduced exercise capacity, primarily owing to limitations in the ability to augment pulmonary blood flow and stroke volume. To date, the mechanism of peak exercise pulmonary blood flow restriction has not been elucidated. We performed a single-center, prospective, crossover trial of supine and upright exercise in Fontan patients and healthy controls to determine the mechanisms of exercise limitation in the Fontan-palliated patient. A total of 29 Fontan patients and 16 control subjects completed the protocol. The duration of exercise, percentage of predicted peak oxygen consumption (VO 2 ) and peak work were reduced in the Fontan group, regardless of posture (p ≤0.03). The percentage of predicted oxygen pulse, a surrogate for pulmonary stroke volume, was not increased with supine posture in the Fontan cohort (upright, 82.3 ± 18.8% vs supine, 82.4 ± 19.7%; p = 0.6). In both groups, the percentage of predicted peak VO 2 was lower with supine exercise than with upright exercise (p ≤0.002). Diastolic dysfunction was present in 57% of the Fontan patients and was associated with a reduced percentage of predicted peak VO 2 (p = 0.04) and supine peak work (p = 0.008). Six Fontan patients who underwent supine exercise with indwelling catheters failed to demonstrate the expected decrease in pulmonary vascular resistance characteristically seen with peak exercise (at rest, 2.8 ± 0.7 mm Hg/L/min/m 2 vs at peak, 2.8 ± 0.9 mm Hg/L/min/m 2 ; p = 0.9). In conclusion, supine exercise in Fontan patients does not result in an increased VO 2 or oxygen pulse, suggesting that inadequate venous return might not be the primary limitation of exercise capacity in this population. Diastolic dysfunction and relatively excessive peak exercise pulmonary vascular resistance might be more important factors in Fontan exercise limitation.

77 citations

Journal ArticleDOI
TL;DR: In this paper, the authors review and assess the data base for shock boundary-layer interaction that is pertinent to the flow prediction in supersonic inlets and identify specific areas related to shock wave/boundary layer interaction bleed, for flow separation control.
Abstract: The performance of supersonic inlets is strongly affected by the boundary-layer development over its internal surfaces. Boundary-layer bleed is used to suppress separation and to provide the desired inlet performance. The gain in pressure recovery and stability is accompanied, however, with a loss in mass flow and an increase in drag that must be minimized by optimizing the amount of bleed and bleed configuration. The purpose of this work is to review and assess the data base for shock boundary-layer interaction that is pertinent to the flow prediction in supersonic inlets. The first part of the review concerns mixed compression supersonic inlets and their bleed system performance at design and off-design conditions. Based on the assessment of this data, specific areas related to shock wave/boundary-layer interaction bleed, for flow-separation control, are identified, the last part of the review addresses this phenomena in various twoand three-dimensional flow configurations. The effect of bleed in the interaction zone is especially emphasized.

77 citations


Authors

Showing all 5825 results

NameH-indexPapersCitations
John A. Rogers1771341127390
Liming Dai14178182937
Mark C. Hersam10765946813
Gareth H. McKinley9746734624
Robert E. Cohen9141232494
Michael F. Rubner8730129369
Howard E. Katz8747527991
Melvin E. Andersen8351726856
Eric A. Stach8156542589
Harry L. Anderson8039622221
Christopher K. Ober8063129517
Vladimir V. Tsukruk7948128151
David C. Look7852628666
Richard A. Vaia7632425387
Kirk S. Schanze7351219118
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20234
202211
2021279
2020298
2019290
2018272