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Proposed expandable bag contains debris from explosion. Permanently surrounds vessel or devices prone to explosive disintegration or slipped around small bomb. Finned cells shaped like outward-opening cups. Cells built up from overlapped sheets of fabric and stitched together to form expandable polyhedral bag. Cells pentagonal, triangular or square.
Device uses friction to dissipate kinetic energy. When moving mass pushes in one direction, it offers substantial friction. Pushed in opposite direction, it offers negligible friction. Built-in spring resets for another shock-absorption cycle. Used in industrial machinery, automobile bumpers and suspensions, and parachute lanyards.
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Optical emission has been observed corresponding to vibrational bands in the NH (A 3Pi - X 3Sigma(-)) electronic transition during collisions of 5 eV, ground-state oxygen O(3P) atoms with MgF2 and Ni surfaces continuously exposed to a beam of hydrazine (N2H4). The NH emission intensity is observed to be about five times greater for MgF2 than for Ni. No dependence on temperature was observed for either surface in the range 240 - 340 K, implying that the NH-producing intermediate species is tightly bound. The half-lifetime for desorption of hydrazine from each surface was measured. This was found to be 120 min for the MgF2 surface at 240 K, and less than 20 min for Ni. After exposure, the surface composition was measured using X-ray photoelectron spectroscopy on the exposed and unexposed areas of both targets.
Modified process for anodizing 5657 aluminum alloy results in Al2O3 surfaces with infrared emissivities as great as 0.92 and solar absorptivities as small as 0.2. Coating enables fabrication of radiators requiring less surface, and hence less weight: radiators with coating weigh approximately 7 percent less than thermally equivalent radiators made with older anodizing processes. Coating applied easily and economically, and retains all of desirable properties of standard anodized coatings.
Leaves of the dominant grass species of the ISCLP FIFE site reflect and transmit radiation in a like manner to other healthy green leaves. Visible reflectance factors (RFs) and transmittance factors (TFs) were less for older leaves than younger leaves except during senescence, when RF and TF values were greater. NIR-RF values increased and TF values decreased with leaf age, with the reverse occurring as the leaf went through senescence.
A process is described for producing gold black films with high absorptance in the far IR. The optical and electrical properties of these films have been studied with particular emphasis on the absorptance of films at wavelengths as long as 50 microns. A substantial decrease in absorptance near 50 microns has been observed for pure gold black films on aging in air. This degradation can be largely avoided by alloying the gold with a small percentage of copper during the deposition. Preliminary results on two methods for delineating gold black films are also presented.
An analytical solution was obtained by Siegel (1991, 1992) for local boundary heat fluxes by a radiating medium at uniform temperature in a 2D rectangular region. It is shown here that, after local fluxes from the medium to the walls have been evaluated, it is very easy to compute local fluxes arriving from the adjacent and opposite walls. This extends the previous analysis and provides convenient relations to include radiation from a black boundary, each side of the rectangle being at a different uniform temperature. The final expressions are helpful in performing spectral calculations that must be made for many spectral bands.
The energy absorption response and crushing characteristics of geometrically scaled graphite-Kevlar epoxy composite plates were investigated. Three different trigger mechanisms including chamfer, notch, and steeple geometries were incorporated into the plate specimens to initiate crushing. Sustained crushing was achieved with a simple test fixture which provided lateral support to prevent global buckling. Values of specific sustained crushing stress (SSCS) were obtained which were comparable to values reported for tube specimens from previously published data. Two sizes of hybrid plates were fabricated; a baseline or model plate, and a full-scale plate with in-plane dimensions scaled by a factor of two. The thickness dimension of the full-scale plates was increased using two different techniques; the ply-level method in which each ply orientation in the baseline laminate stacking sequence is doubled, and the sublaminate technique in which the baseline laminate stacking sequence is repeated as a group. Results indicated that the SSCS is independent of trigger mechanism geometry. However, a reduction in the SSCS of 10-25 percent was observed for the full-scale plates as compared with the baseline specimens, indicating a scaling effect in the crushing response.
Laboratory spectra through the mid-infrared (4000 to 500/cm (2.5-20 microns) have been used to calculate the optical constants (n and k) and integrated absorption coefficients (A) for a variety of pure and mixed molecular ices of relevance to astrophysics. The ices studied were H2O, CH3OH, CO2, OCS, CH4, CO2 + CH4, CO2 + OCS, CO + CH4, CO + OCS, O2 + CH4, O2 + OCS, N2 + CH4, N2 + OCS, H2O + CH4, H2O + OCS, and H2O + CH3OH + CO + NH3. In addition, the measurements have been extended through the far-infrared (500 to 50/cm (20-200 microns) for the H2O, CH3OH, and H2O + CH3OH + CO + NH3 ices.
The H I column density distribution function of QSO absorption line systems is investigated using recent data with high spectral resolution, and extensive surveys of the Lyman limit systems and damped Ly-alpha systems. The hypothesis that the differential distribution function is fitted by a single power law is rejected at the 99 percent confidence level. A double power law, with a break at N(H I) = 10 exp 16/sq cm, also provides a poor fit over the range in which the sample is complete. While there are no discontinuities in the observed distribution, there is a clear flattening at N(H I) of about 10 exp 16/sq cm, compared to lower column densities. These observed features can be understood using models of photoionized clouds which are confined by an external pressure with density profiles governed by gravity. In particular, the flattening at N(H I) of about 10 exp 16/sq cm can be explained in terms of a transition between metal-poor and metal-rich systems.
NASA-Johnson has acquired a preprototype/full-scale metal oxide CO2 and humidity remover (MOCHR), together with its regeneration module. Tests conducted prior to delivery by the MOCHR's manufacturer have demonstrated the concurrent removal of H2O and CO2 at rates, and under conditions, that are applicable to EVA Portable Life Support Systems.
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