12,542 research outputs found
Pretreatment method for anti-wettable materials
Anti-wettable materials brazing processes using titanium and zirconium for surface pretreatmen
Development of battery separator material process Mid-program report
Heat sterilizable battery separator material prepared from low-density polyethylene fil
Development of battery separator material process Interim report
Sterilizable battery separator material preparation proces
Structural characterization of Si(m)Ge(n) strained layer superlattices
SimGen strained layer superlattice (SLS) structures were grown by molecular beam epitaxy on GexSi1-x buffer layers on Si substrates to determine the effects of buffer layer composition, SLS thickness ratio, and superlattice periodicity, on the overall quality of these structures. X-ray diffraction methods were used to determine how closely actual periodicities and compositions met targeted values, and to evaluate the quality of these samples. In most instances the as-grown structures matched the targeted values to within 10%, though in some instances deviations of 20-25% in either the period or composition were observed. The quality of the SLS structures was greatly dependent on the composition of the buffer layer on which it was grown. SimGen SLS structures grown on Si- and Ge-rich buffer layers were of much higher quality than SimGem SLSs grown on Ge0.50Si0.50 layers, but the x-ray rocking curves of the SimGen samples indicated that they were far from perfect and contained moderate levels of defects. These results were confirmed by cross sectional transmission electron microscopy, which showed that the SimGem structures contained significant numbers of dislocations and that the layers were nonuniform in thickness and wavy in appearance. SimGen structures, however, displayed fewer defects but some dislocations and nonparallelism of layers were still observed
Investigation and suppression of high dynamic response encountered on an elastic supercritical wing
The DAST Aeroelastic Research Wing had been previously in the NASA Langley TDT and an unusual instability boundary was predicted based upon supercritical response data. Contrary to the predictions, no instability was found during the present test. Instead a region of high dynamic wing response was observed which reached a maximum value between Mach numbers 0.92 and 0.93. The amplitude of the dynamic response increased directly with dynamic pressure. The reponse appears to be related to chordwise shock movement in conjunction with flow separation and reattachment on the upper and lower wing surfaces. The onset of flow separation coincided with the occurrence of strong shocks on a surface. A controller was designed to suppress the wing response. The control law attenuated the response as compared with the uncontrolled case and added a small but significant amount of damping for the lower density condition
Large perturbation flow field analysis and simulation for supersonic inlets
An analysis technique for simulation of supersonic mixed compression inlets with large flow field perturbations is presented. The approach is based upon a quasi-one-dimensional inviscid unsteady formulation which includes engineering models of unstart/restart, bleed, bypass, and geometry effects. Numerical solution of the governing time dependent equations of motion is accomplished through a shock capturing finite difference algorithm, of which five separate approaches are evaluated. Comparison with experimental supersonic wind tunnel data is presented to verify the present approach for a wide range of transient inlet flow conditions
Fabrication and testing of battery separator material from modified polyethylene Final report
Fabrication and testing of battery separator material of modified polyethylene fil
Tachyons in Compact Spaces
We discuss condensations of closed string tachyons localized in compact
spaces. Time evolution of an on-shell condensation is naturally related to the
worldsheet RG flow. Some explicit tachyonic compactifications of Type II string
theory is considered, and some of them are shown to decay into supersymmetric
theories known as the little string theories.Comment: 14 page
Cross Section Measurements Using the Zero Degree Detector
The Zero Degree Detector (ZDD) is an instrument that has been used in accelerator exposures to measure the angular dependence of particles produced in heavy ion fragmentation experiments. The ZDD uses two identical layers of pixelated silicon detectors that make coincident measurements over the active area of the instrument. The angular distribution of secondary particle produced in nuclear interactions for several heavy ions: and target materials will be presented along with performance characteristic of the instrument
Ptychographic hyperspectral spectromicroscopy with an extreme ultraviolet high harmonic comb
We demonstrate a new scheme of spectromicroscopy in the extreme ultraviolet
(EUV) spectral range, where the spectral response of the sample at different
wavelengths is imaged simultaneously. It is enabled by applying ptychographical
information multiplexing (PIM) to a tabletop EUV source based on high harmonic
generation, where four spectrally narrow harmonics near 30 nm form a spectral
comb structure. Extending PIM from previously demonstrated visible wavelengths
to the EUV/X-ray wavelengths promises much higher spatial resolution and more
powerful spectral contrast mechanism, making PIM an attractive
spectromicroscopy method in both the microscopy and the spectroscopy aspects.
Besides the sample, the multicolor EUV beam is also imaged in situ, making our
method a powerful beam characterization technique. No hardware is used to
separate or narrow down the wavelengths, leading to efficient use of the EUV
radiation
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