6,824 research outputs found
A Flight Investigation of the STOL Characteristics of an Augmented Jet Flap STOL Research Aircraft
The flight test program objectives are: (1) To determine the in-flight aerodynamic, performance, and handling qualities of a jet STOL aircraft incorporating the augmented jet flap concept; (2) to compare the results obtained in flight with characteristics predicted from wind tunnel and simulator test results; (3) to contribute to the development of criteria for design and operation of jet STOL transport aircraft; and (4) to provide a jet STOL transport aircraft for STOL systems research and development. Results obtained during the first 8 months of proof-of-concept flight testing of the aircraft in STOL configurations are reported. Included are a brief description of the aircraft, fan-jet engines, and systems; a discussion of the aerodynamic, stability and control, and STOL performance; and pilot opinion of the handling qualities and operational characteristics
Operational experience with a powered-lift STOL aircraft
The experience gained in over four years of STOL operations with the augmentor wing research aircraft and the background of operation of other STOL powered-lift aircraft indicate that the use and percent of lift achieved by powered lift have significant effects on the operational characteristics of STOL aircraft and, therefore, on the performance that can be achieved. A brief description of the augmentor wing including the means by which it achieves its powered lift is presented. Specific problem areas relating to the control of longitudinal flight path are discussed as well as the consequences these might have on the design and operation of this class of aircraft. Particular emphasis is given to the approach and landing phase of flight where the consequences of the powered lift are most pronounced, and the resultant characteristics most different from those of conventional aircraft
Lattice thermal conductivity of graphene nanostructures
Non-equilibrium molecular dynamics is used to investigate the heat current
due to the atomic lattice vibrations in graphene nanoribbons and nanorings
under a thermal gradient. We consider a wide range of temperature, nanoribbon
widths up to 6nm and the effect of moderate edge disorder. We find that narrow
graphene nanorings can efficiently suppress the lattice thermal conductivity at
low temperatures (~100K), as compared to nanoribbons of the same width.
Remarkably, rough edges do not appear to have a large impact on lattice energy
transport through graphene nanorings while nanoribbons seem more affected by
imperfections. Furthermore, we demonstrate that the effects of
hydrogen-saturated edges can be neglected in these graphene nanostructures
Disseminated chlorellosis in a dog
An adult dog with ataxia and a lingual mass, previously diagnosed as protothecosis, was euthanized. At the postmortem examination, the lingual mass, regions of the lungs and hilar lymph nodes, liver, mesenteric and sublumbar lymph nodes, and spinal meninges had pronounced green discoloration. Histologically, pyogranulomatous inflammation and algal organisms were found in the tongue, spinal meninges, hilar and mesenteric lymph nodes, liver, and lung. The algae had cell walls positive for periodic acid-Schiff and cytoplasmic granules. Ultrastructurally, the algae had a well-defined cell wall, stacks of grana and thylakoid membrane, and dense bodies, typical of starch granules. The organisms were identified as Chlorella, a green alga, based on the results of histochemistical and electron microscopic examination. To the author's knowledge this is the first report of disseminated Chlorella infection and the first report in a companion animal.The published version of this article may be found at http://www.vetpathology.org/cgi/content/abstract/46/3/43
The Cut-Constructible Part of QCD Amplitudes
Unitarity cuts are widely used in analytic computation of loop amplitudes in
gauge theories such as QCD. We expand upon the technique introduced in
hep-ph/0503132 to carry out any finite unitarity cut integral. This technique
naturally separates the contributions of bubble, triangle and box integrals in
one-loop amplitudes and is not constrained to any particular helicity
configurations. Loop momentum integration is reduced to a sequence of algebraic
operations. We discuss the extraction of the residues at higher-order poles.
Additionally, we offer concise algebraic formulas for expressing coefficients
of three-mass triangle integrals. As an application, we compute all remaining
coefficients of bubble and triangle integrals for nonsupersymmetric six-gluon
amplitudes.Comment: 78 pages, 3 fig
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