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

The COLD-SAT Experiment for Cryogenic Fluid Management Technology

Future national space transportation missions will depend on the use of cryogenic fluid management technology development needs for these missions. In-space testing will be conducted in order to show low gravity cryogenic fluid management concepts and to acquire a technical data base. Liquid H2 is the preferred test fluid due to its propellant use. The design of COLD-SAT (Cryogenic On-orbit Liquid Depot Storage, Acquisition, and Transfer Satellite), an Expendable Launch Vehicle (ELV) launched orbital spacecraft that will perform subcritical liquid H2 storage and transfer experiments under low gravity conditions is studied. An Atlas launch vehicle will place COLD-SAT into a circular orbit, and the 3-axis controlled spacecraft bus will provide electric power, experiment control, and data management, attitude control, and propulsive accelerations for the experiments. Low levels of acceleration will provide data on the effects that low gravity might have on the heat and mass transfer processes used. The experiment module will contain 3 liquid H2 tanks; fluid transfer, pressurization and venting equipment; and instrumentation

A Selective Advantage for Conservative Viruses

In this letter we study the full semi-conservative treatment of a model for the co-evolution of a virus and an adaptive immune system. Regions of viability are calculated for both conservatively and semi-conservatively replicating viruses interacting with a realistic semi-conservatively replicating immune system. The conservative virus is found to have a selective advantage in the form of an ability to survive in regions with a wider range of mutation rates than its semi-conservative counterpart. This may help explain the existence of a rich range of viruses with conservatively replicating genomes, a trait which is found nowhere else in nature.Comment: 4 pages, 2 figure

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