Two challenging problems still remain for optical absorbers consisting of an ultrathin planar semiconductor film on top of an opaque metallic substrate. One is the angle-insensitive mechanism and the other is the system design needed for broadband solar energy harvesting. Here, first we theoretically demonstrates that the high refractive index, instead of the ultrathin feature as reported in pr...

Proton beams in medical applications deal with relatively thick targets like the human head or trunk. Therefore, relatively small differences in the total proton stopping power given, for example, by the different models provided by GEANT4 can lead to significant disagreements in the final proton energy spectra when integrated along lengthy proton trajectories. This work presents proton energy ...

We report the first high-pressure single-crystal structures of hybrid perovskites. The crystalline semiconductors (MA)PbX3 (MA = CH3NH3 (+), X = Br(-) or I(-)) afford us the rare opportunity of understanding how compression modulates their structures and thereby their optoelectronic properties. Using atomic coordinates obtained from high-pressure single-crystal X-ray diffraction we track the pe...

Large emittance muon beam must be reduced or cooled both longitudinally and transversely before it can be accelerated in an accelerator complex for a neutrino factory or a muon collider. In practice, ionization cooling is considered to be one of the most promising transverse cooling schemes for muon beams. When traversing an ionization cooling channel, which consists of absorbers and low freque...

To study the nature of low z Lyα absorbers in the spectra of QSOs, we have obtained high signalto-noise UV spectra of H 1821+643 (zem = 0.297) and PG 1116+215 (zem = 0.177) with the Goddard High Resolution Spectrograph on the Hubble Space Telescope. The spectra have minimum S/N ∼ 70-100 and 3σ limiting equivalent widths of 50-75 mÅ at a resolution of ∼150 km s. Excluding lines within 3000 km s ...

One way to characterize and understand H I-selected galaxies is to study their metallicity properties. In particular, we show that the metallicity of absorbers is a bivariate function of the H I column density (NH I) and the Mg II equivalent width (W λ2796 r ). Thus, a selection upon W r is not equivalent to a H I selection for intervening absorbers. A direct consequence for damped absorbers wi...

We use the observed number and column-density distributions of intergalactic O VI absorbers to constrain the distribution of metals in the low-redshift intergalactic medium (IGM). In this simple model the metals in the O VI absorbers are assumed to be produced in and propagated from lowredshift galaxies drawn from a real sample, in this case the Sloan Digital Sky Survey (SDSS). This model can e...

Title of dissertation: HIGH STRENGTH SEMI-ACTIVE ENERGY ABSORBERS USING SHEARAND MIXED-MODE OPERATION AT HIGH SHEAR RATES Andrew Craig Becnel Doctor of Philosophy, 2014 Dissertation directed by: Professor Norman M. Wereley Department of Aerospace Engineering This body of research expands the design space of semi-active energy absorbers for shock isolation and crash safety by investigating and c...

In this paper the potential of kinetic energy absorption by means absorbing and storing mechanisms was discussed. The use absorbers is intended to reduce maximum working forces when stopping body.