Radar spectral measurements of vegetation

Spectral data of 4-8 GHz radar backscatter were gathered during the 1972 growing season at look angles between 0 and 70 deg and for all four possible polarization linear combinations. The data covers four crop types (corn, milo, alfalfa, and soybeans) and a wide range of soil moisture content. To insure statistical representation of the results, measurements were conducted over 128 fields corresponding to a total of about 40,000 data points. The use of spectral response signatures to separate different crop types and to separate healthy corn from blighted corn was investigated

Evaluation criteria for commercially oriented materials processing in space proposals

An approach and criteria for evaluating NASA funded experiments and demonstrations which have commercial potential were developed. Methods for insuring quick initial screening of commercial proposals are presented. Recommendations are given for modifying the current evaluation approach. New criteria for evaluating commercially orientated materials processing in space (MPS) proposals are introduced. The process for selection of qualified individuals to evaluate the phases of this approach and criteria is considered and guidelines are set for its implementation

Space shuttle: Supersonic aerodynamic characteristics of the MSC 040A orbiter (M equals 2.0 to 4.0)

A wind tunnel test of the space shuttle orbiter configuration 040A was run in a 20 in. supersonic wind tunnel. Basic aerodynamic data for this vehicle were determined at Mach 2.0, 2.4, 3.0 and 4.0

Small quantity production of complex chromium alloy sheet /Cr-7Mo-2Ta-0.09C-0.1Y/ Final report

Fabrication of Cr-Mo-Ta-C-Y alloy shee

Continuous-wave Cascaded-Harmonic Generation and Multi-Photon Raman Lasing in Lithium Niobate Whispering-Gallery Resonators

We report experimental demonstration of continuous-wave cascaded-harmonic generation and Raman lasing in a millimeter-scale lithium niobate whispering-gallery resonator pumped at a telecommunication-compatible infrared wavelength. Intensity enhancement through multiple recirculations in the whispering-gallery resonator and quasi phase-matching through a nonuniform crystal poling enable simultaneous cascaded-harmonic generation up to the fourth-harmonic accompanied by stimulated Raman, two-photon, three-photon, and four-photon Raman scattering corresponding the molecular vibrational wavenumbers 632 cm-1 and 255 cm-1 in z-cut lithium niobate at pump power levels as low as 200mW. We demonstrate simultaneous cascaded-harmonic generation and Raman lasing by observing the spectrum of the scattered light from the resonator and by capturing the image of the decoupled light from the resonator on a color CCD camera

5D Black Rings and 4D Black Holes

It has recently been shown that the M theory lift of a IIA 4D BPS Calabi-Yau black hole is a 5D BPS black hole spinning at the center of a Taub-NUT-flux geometries, and a certain linear relation between 4D and 5D BPS partition functions was accordingly proposed. In the present work we fortify and enrich this proposal by showing that the M-theory lift of the general 4D multi-black hole geometry are 5D black rings in a Taub-NUT-flux geometry.Comment: 8 pages; version 2, with additional references and explanation

Mechanism for the failure of the Edwards hypothesis in the SK spin glass

The dynamics of the SK model at T=0 starting from random spin configurations is considered. The metastable states reached by such dynamics are atypical of such states as a whole, in that the probability density of site energies, $p(\lambda)$, is small at $\lambda=0$. Since virtually all metastable states have a much larger $p(0)$, this behavior demonstrates a qualitative failure of the Edwards hypothesis. We look for its origins by modelling the changes in the site energies during the dynamics as a Markov process. We show how the small $p(0)$ arises from features of the Markov process that have a clear physical basis in the spin-glass, and hence explain the failure of the Edwards hypothesis.Comment: 5 pages, new title, modified text, additional reference

Resolving the Structure of Cold Dark Matter Halos

We examine the effects of mass resolution and force softening on the density profiles of cold dark matter halos that form within cosmological N-body simulations. As we increase the mass and force resolution, we resolve progenitor halos that collapse at higher redshifts and have very high densities. At our highest resolution we have nearly 3 million particles within the virial radius, several orders of magnitude more than previously used and we can resolve more than one thousand surviving dark matter halos within this single virialised system. The halo profiles become steeper in the central regions and we may not have achieved convergence to a unique slope within the inner 10% of the virialised region. Results from two very high resolution halo simulations yield steep inner density profiles, $\rho(r)\sim r^{-1.4}$. The abundance and properties of arcs formed within this potential will be different from calculations based on lower resolution simulations. The kinematics of disks within such a steep potential may prove problematic for the CDM model when compared with the observed properties of halos on galactic scales.Comment: Final version, to be published in the ApJLetter

Fatigue testing a plurality of test specimens and method

Described is a fatigue testing apparatus for simultaneously subjecting a plurality of material test specimens to cyclical tension loading to determine the fatigue strength of the material. The fatigue testing apparatus includes a pulling head having cylinders defined therein which carry reciprocating pistons. The reciprocation of the pistons is determined by cyclical supplies of pressurized fluid to the cylinders. Piston rods extend from the pistons through the pulling head and are attachable to one end of the test specimens, the other end of the test specimens being attachable to a fixed base, causing test specimens attached between the piston rods and the base to be subjected to cyclical tension loading. Because all the cylinders share a common pressurized fluid supply, the breaking of a test specimen does not substantially affect the pressure of the fluid supplied to the other cylinders nor the tension applied to the other test specimens

Wind tunnel turning vanes of modern design

Rehabilitation of the Altitude Wind Tunnel includes the need for new corner turning vanes to match its upgraded performance. The design and experimental performance results from a 0.1-full scale model of the highest speed corner (M = 0.35) are presented and discussed along with some two dimensional inviscid analyses of two vaned corners. With a vane designed by an inverse two dimensional technique, the overall corner loss was about 12% of the inlet dynamic pressure of which about 4% was caused by vane skin friction. Comparable values with a conventionally designed circular arc vane were about 14% overall with about 7% due to skin friction