8,304 research outputs found
Antenna beam-shaping apparatus Patent
Device for improving efficiency of parabolic horn antenna system for linearly polarized signal
Parabolic reflector horn feed with spillover correction Patent
Device for improving efficiency of parabolic reflector horn for linearly or circularly polarized wave
Insertion loss measuring apparatus having transformer means connected across a pair of bolometers Patent
High impedance alternating current sensing transformer device between two bolometers for measuring insertion loss of test componen
Do columnar defects produce bulk pinning?
From magneto-optical imaging performed on heavy-ion irradiated YBaCuO single
crystals, it is found that at fields and temperatures where strong single
vortex pinning by individual irradiation-induced amorphous columnar defects is
to be expected, vortex motion is limited by the nucleation of vortex kinks at
the specimen surface rather than by half-loop nucleation in the bulk. In the
material bulk, vortex motion occurs through (easy) kink sliding. Depinning in
the bulk determines the screening current only at fields comparable to or
larger than the matching field, at which the majority of moving vortices is not
trapped by an ion track.Comment: 5 pages, 5 figures, submitted to Physical Review Letter
Cold Formed Steel Tension Members with Two and Three Staggered Bolts
The second edition of the North American Specification for the Design of Cold Formed Steel Structural Members was published in October of 2007 for use in Canada, Mexico, and the United States. This Specification contains two country specific a ppe ndices, namely Appendix A (ANSI/AISI S100- 07) for use in the US and Mexico and Appendix B (CSA S136- 07) for use in Canada. Both Appendix A and B require that a bolt stagger reduction factor of 0.90 be used when calculating the tearing failure strength [resistance] of a cold formed steel member in tension with staggered bolts. This 10% reduction was based on limited testing that was carried out by Dr. Roger LaBoube of the University of Missouri-Rolla, which has now changed its name to the Missouri University of Science & Technology . The objective of this study was to establish if this bolt stagger reduction factor is indeed necessary since the stagger term of [s 2 /4g] has been used in the steel industry for many years without such a reduction. Experimental testing of two and three staggered bolt tension members was carried out in the Structures Laboratory of the Department of Civil Engineering at the University of Waterloo. Based on the test results of the 1.6 mm, 2.1 mm, 2.9 mm, 4 mm, 5 mm, and 6 mm thick steel sheet, it can be concluded that the 0.90 bolt stagger reduction factor is not necessary for the steel plate thicknesses tested
Computation of aircraft component flow fields at transonic Mach numbers using a three-dimensional Navier-Stokes algorithm
A computer analysis was developed for calculating steady (or unsteady) three-dimensional aircraft component flow fields. This algorithm, called ENS3D, can compute the flow field for the following configurations: diffuser duct/thrust nozzle, isolated wing, isolated fuselage, wing/fuselage with or without integrated inlet and exhaust, nacelle/inlet, nacelle (fuselage) afterbody/exhaust jet, complete transport engine installation, and multicomponent configurations using zonal grid generation technique. Solutions can be obtained for subsonic, transonic, or hypersonic freestream speeds. The algorithm can solve either the Euler equations for inviscid flow, the thin shear layer Navier-Stokes equations for viscous flow, or the full Navier-Stokes equations for viscous flow. The flow field solution is determined on a body-fitted computational grid. A fully-implicit alternating direction implicit method is employed for the solution of the finite difference equations. For viscous computations, either a two layer eddy-viscosity turbulence model or the k-epsilon two equation transport model can be used to achieve mathematical closure
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