5,484 research outputs found
The Effect of the Wings of Single Engine Airplanes on Propulsive Efficiency as Shown by Full Scale Wind Tunnel Tests
An investigation was conducted to determine the effect of the wings on propulsive efficiency. The wings are shown to cause a reduction of 1 percent to 3 percent in propulsive efficiency, which is about the same for monoplane as well as biplane wings
Isochronicity Correction in the CR Storage Ring
A challenge for nuclear physics is to measure masses of exotic nuclei up to
the limits of nuclear existence which are characterized by low production cross
sections and short half-lives. The large acceptance Collector Ring (CR) at FAIR
tuned in the isochronous ion-optical mode offers unique possibilities for
measuring short-lived and very exotic nuclides. However, in a ring designed for
maximal acceptance, many factors limit the resolution. One point is a limit in
time resolution inversely proportional to the transverse emittance. But most of
the time aberrations can be corrected and others become small for large number
of turns. We show the relations of the time correction to the corresponding
transverse focusing and that the main correction for large emittance
corresponds directly to the chromaticity correction for transverse focusing of
the beam. With the help of Monte-Carlo simulations for the full acceptance we
demonstrate how to correct the revolution times so that in principle
resolutions of dm/m=1E-6 can be achieved. In these calculations the influence
of magnet inhomogeneities and extended fringe fields are considered and a
calibration scheme also for ions with different mass-to-charge ratio is
presented.Comment: 6 figures, recised version May 201
The Twenty-Foot Propeller Research Tunnel of the National Advisory Committee for Aeronautics
This report describes in detail the new propeller research tunnel of the National Advisory Committee for Aeronautics at Langley Field, Va. This tunnel has an open jet air stream 20 feet in diameter in which velocities up to 110 M. P. H. Are obtained. Although the tunnel was built primarily to make possible accurate full-scale tests on aircraft propellers, it may also be used for making aerodynamic tests on full-size fuselages, landing gears, tail surfaces, and other aircraft parts, and on model wings of large size. (author
Federal Appellate Court Decision in Environmental Defense Fund et al., Plaintiffs Appellees, v. Tennessee Valley Authority et al., Defendants-Appellants, No. 74-1139
Federal Appellate Court decision in the case of EDF v. TVA, upholding the lower court\u27s decision in favor of TVA, allowing the construction of the Tellico Dam to go forward. This decision was published in West\u27s Federal Reporter at 492 F.2d 466 (1974)
Complementary Photocatalytic Toolbox: Control of Intramolecular endo-versus exo-trig Cyclizations of α-Phenyl Olefins to Oxaheterocyclic Products
The regioselectivity of the intramolecular cyclization of bifunctional α-phenyl alkenes can be controlled simply by the choice of the organic chromophore as the photocatalyst. The central photoredox catalytic reaction in both cases is a nucleophilic addition of the hydroxy function to the olefin function of the substrates. N,N-(4-Diisobutylaminophenyl)phenothiazine catalyzes exo-trig cyclizations, whereas 1,7-dicyanoperylene-3,4,9,10-tetracarboxylic acid bisimides catalyze endo-trig additions to products with anti-Markovnikov regioselectivity. We preliminarily report the photoredox catalytic conversions of 11 representative substrates into 20 oxaheterocycles in order to demonstrate the similarity, but also the complementarity, of these two variants in this photoredox catalytic toolbox
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