3,641 research outputs found
Hot air ballon deceleration and recovery system Patent
Development and characteristics of hot air balloon deceleration and recovery syste
Drag coefficients for partially inflated flat circular parachutes
Free-body tests of flat circular parachutes and determination of aerodynamic drag coefficients during partial inflatio
Low-speed aerodynamic characteristics of a 0.08-scale YF-17 airplane model at high angles of attack and sideslip
Data were obtained with and without the nose boom and with several strake configurations; also, data were obtained for various control surface deflections. Analysis of the results revealed that selected strake configurations adequately provided low Reynolds number simulation of the high Reynolds number characteristics. The addition of the boom in general tended to reduce the Reynolds number effects
Low speed aerodynamic characteristics of an 0.075-scale F-15 airplane model at high angles of attack and sideslip
An 0.075 scale model representative of the F-15 airplane was tested in the Ames 12 foot pressure wind tunnel at a Mach number of 0.16 to determine static longitudinal and lateral directional characteristics at spin attitudes for Reynolds numbers from 1.48 to 16.4 million per meter (0.45 to 5.0 million per foot). Angles of attack ranged from 0 to +90 deg and from -40 deg to -80 deg while angles of sideslip were varied from -20 deg to +30 deg. Data were obtained for nacelle inlet ramp angles of 0 to 11 deg with the left and right stabilators deflected 0, -25 deg, and differentially 5 deg and -5 deg. The normal pointed nose and two alternate nose shapes were also tested along with several configurations of external stores. Analysis of the results indicate that at higher Reynolds numbers there is a slightly greater tendency to spin inverted than at lower Reynolds numbers. Use of a hemispherical nose in place of the normal pointed nose provided an over correction in simulating yawing moment effects at high Reynolds numbers
Technical Note: Temporal disaggregation of spatial rainfall fields with generative adversarial networks
Creating spatially coherent rainfall patterns with high temporal resolution from data with lower temporal resolution is necessary in many geoscientific applications. From a statistical perspective, this presents a high- dimensional, highly underdetermined problem. Recent advances in machine learning provide methods for learning such probability distributions. We test the usage of generative adversarial networks (GANs) for estimating the full probability distribution of spatial rainfall patterns with high temporal resolution, conditioned on a field of lower temporal resolution. The GAN is trained on rainfall radar data with hourly resolution. Given a
new field of daily precipitation sums, it can sample scenarios of spatiotemporal patterns with sub-daily resolution. While the generated
patterns do not perfectly reproduce the statistics of observations,
they are visually hardly distinguishable from real patterns. Limitations that we found are that providing additional input (such as geographical information) to the GAN surprisingly leads to worse results, showing that it is not trivial to increase the amount of used input information. Additionally, while in principle the GAN should learn the probability distribution in itself, we still needed expert judgment to determine at which point the training should stop, because longer training leads to worse results.</p
Finite size effects on in QCD from Chiral Perturbation Theory
We present a determination of the shift due to the finite
spatial box size by means of Chiral Perturbation Theory and
L\"uscher's formula. The range of applicability of the chiral prediction is
discussed.Comment: 3 pages, 3 figures, Lattice2002(spectrum
ANALYTICAL INVESTIGATION AND PREDICTION OF SPIN AND RECOVERY CHARACTERISTICS OF THE NORTH AMERICAN X-15 AIRPLANE
Spin and recovery characteristics of north american x-15 aircraf
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