Institution
Langley Research Center
Facility•Hampton, Virginia, United States•
About: Langley Research Center is a facility organization based out in Hampton, Virginia, United States. It is known for research contribution in the topics: Mach number & Wind tunnel. The organization has 15945 authors who have published 37602 publications receiving 821623 citations. The organization is also known as: NASA Langley & NASA Langley Research Center.
Topics: Mach number, Wind tunnel, Aerodynamics, Boundary layer, Supersonic speed
Papers published on a yearly basis
Papers
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TL;DR: The strategy of using multiple versions of independently developed software as a means to tolerate residual software design faults is discussed and the effectiveness of multiversion software is studied by comparing estimates of the failure probability of these systems with the failure probabilities of single versions.
Abstract: The strategy of using multiple versions of independently developed software as a means to tolerate residual software design faults is discussed. The effectiveness of multiversion software is studied by comparing estimates of the failure probabilities of these systems with the failure probabilities of single versions. The estimates are obtained under a model of dependent failures and compared with estimates obtained when failures are assumed to be independent. The experimental results are based on 20 versions of an aerospace application developed and independently validated by 60 programmers from 4 universities. Descriptions of the application and development process are given, together with an analysis of the 20 versions. >
188 citations
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TL;DR: In this paper, the first survey of CH4 flux from northern peatlands of the United States was presented, with emissions ranging from 0.003 to 1.94 g CH4 m−2 day−1.
Abstract: The concentration of methane (CH4) in the global troposphere is increasing. Ambient air measurements document an approximate rate of increase of 1–2% yr−1 over the past decade1–4. Measurements of CH4 in air bubbles trapped in polar ice indicate that tropospheric concentrations of CH4 several hundred years ago may have been ∼45% of present levels5–7. To understand and assess possible causes of the atmospheric CH4 increase requires improved quantitative knowledge of global sources and sinks of CH4. Previous attempts to estimate sources of atmospheric CH4, based on very few measurements, have suggested that natural and agricultural wetlands are major sources8,9. The major wetland regions of the world are in boreal, low Arctic and tropical ecosystems10. It is these regions, particularly in peatland habitats where major accumulations of organic materials occur under anaerobic conditions, that should be significant sources of global tropospheric CH4. The most extensive peatlands in the world occur in the boreal taiga zone between ∼45° and 65° N latitude. More than 95% of world peat resources occur in the Soviet Union, Canada, the United States, Sweden, Norway, Finland and the United Kingdom10. We report here the first survey of CH4 flux from northern peatlands of the United States. Emission rates ranged from 0.003 to 1.94 g CH4 m−2 day−1, with half of these values between 0.1 and 0.4 g CH4 m−2 day−1. The frequency distribution is log normal (Fig. 1) and the mean emission rate is 0.337 g CH4 m−2 day−1. Such fluxes are higher than most values reported for other ecosystems, suggesting that northern peatlands may be an important source of global tropospheric CH4.
187 citations
01 Jan 1966
TL;DR: Guidelines applicable to grit-type boundary layer transition trips near leading edges of wind tunnel models are given in this article, where the transition point is defined as the leading edge of the wind tunnel model.
Abstract: Guidelines applicable to grit-type boundary layer transition trips near leading edges of wind tunnel models
187 citations
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TL;DR: In this paper, a cubic spline approximation is used for the solution of several problems in fluid mechanics, including the Burgers' equation, the diffusion equation and the vorticity-stream function system describing viscous flow in a driven cavity.
187 citations
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TL;DR: In this paper, a parametric analysis of postbuckled through-width delaminations in laminated coupons was performed, where a finite element analysis was developed to analyze the coupons as a combination of linear and geometrically nonlinear components.
Abstract: A parametric study of postbuckled through-width delaminations in laminated coupons was performed. A finite element analysis was developed to analyze the coupons as a combination of linear and geometrically nonlinear components. Because most of the coupon configuration studied behaves linearly, the mixed linear and nonlinear analysis greatly reduced computational costs. The analysis was verified by comparing numerical with exact solutions for simple hypothetical problems. In addition, measured lateral deflections of postbuckled through-width delaminations in laminated coupons were compared with predicted deflections. In the parametric study, stress distributions and strain-energy release rates were calculated for various delamination lengths, delamination depths, applied loads, and lateral deflections. Also, a small number of coupons with through-width delaminations were fatigue tested to obtain delamination growth data. Calculated strain-energy release rates were compared with the observed growth rates to determine the relative importance of the Mode 1 and Mode 2 components of energy release. Growth process was dominated by G sub I.
187 citations
Authors
Showing all 16015 results
Name | H-index | Papers | Citations |
---|---|---|---|
Daniel J. Jacob | 162 | 656 | 76530 |
Donald R. Blake | 118 | 727 | 49697 |
Veerabhadran Ramanathan | 100 | 301 | 47561 |
Raja Parasuraman | 91 | 402 | 41455 |
Robert W. Platt | 88 | 638 | 31918 |
James M. Russell | 87 | 691 | 29383 |
Daniel J. Inman | 83 | 918 | 37920 |
Antony Jameson | 79 | 474 | 31518 |
Ya-Ping Sun | 79 | 277 | 28722 |
Patrick M. Crill | 79 | 228 | 20850 |
Richard B. Miles | 78 | 759 | 25239 |
Patrick Minnis | 77 | 490 | 23403 |
Robert W. Talbot | 77 | 297 | 19783 |
Raphael T. Haftka | 76 | 773 | 28111 |
Jack E. Dibb | 75 | 344 | 18399 |