Temperature measurements behind reflected shock waves in air

A radiometric method for the measurement of gas temperature in self-absorbing gases has been applied in the study of shock tube generated flows. This method involves making two absolute intensity measurements at identical wavelengths, but for two different pathlengths in the same gas sample. Experimental results are presented for reflected shock waves in air at conditions corresponding to incident shock velocities from 7 to 10 km/s and an initial driven tube pressure of 1 torr. These results indicate that, with this technique, temperature measurements with an accuracy of + or - 5 percent can be carried out. The results also suggest certain facility related problems

Feasibility of using neutron radiography to inspect the Space Shuttle solid rocket booster aft skirt, forward skirt and frustum. Part 1: Summary report

The space shuttle's solid rocket boosters (SRB) include components made primarily of aluminum that are parachuted back for retrieval from the ocean and refurbished for repeated usage. Nondestructive inspection methods used on these aging parts to reduce the risk of unforeseen problems include x-ray, ultrasonics, and eddy current. Neutron radiography tests on segments of an SRB component show that entrapped moisture and naturally occurring aluminum corrosion can be revealed by neutron radiography even if present in only small amounts. Voids in sealant can also be evaluated. Three alternatives are suggested to follow-up this study: (1) take an SRB component to an existing neutron radiography system; (2) take an existing mobile neutron radiography system to the NASA site; or (3) plan a dedicated system custom designed for NASA applications

Quantized time correlation function approach to non-adiabatic decay rates in condensed phase: Application to solvated electrons in water and methanol

A new, alternative form of the golden rule formula defining the non-adiabatic transition rate between two quantum states in condensed phase is presented. The formula involves the quantum time correlation function of the energy gap, of the non-adiabatic coupling, and their cross terms. Those quantities can be inferred from their classical counterparts, determined via MD simulations. The formalism is applied to the problem of the non-adiabatic relaxation of an equilibrated p-electron in water and methanol. We find that, in both solvent, the relaxation is induced by the coupling to the vibrational modes and the quantum effects modify the rate by a factor of 2-10 depending on the quantization procedure applied. The resulting p-state lifetime for a hypothetical equilibrium excited state appears extremely short, in the sub-100 fs regime. Although this result is in contrast with all previous theoretical predictions, we also illustrate that the lifetimes computed here are very sensitive to the simulated electronic quantum gap and to the strongly correlated non-adiabatic coupling

Connected component identification and cluster update on GPU

Cluster identification tasks occur in a multitude of contexts in physics and engineering such as, for instance, cluster algorithms for simulating spin models, percolation simulations, segmentation problems in image processing, or network analysis. While it has been shown that graphics processing units (GPUs) can result in speedups of two to three orders of magnitude as compared to serial codes on CPUs for the case of local and thus naturally parallelized problems such as single-spin flip update simulations of spin models, the situation is considerably more complicated for the non-local problem of cluster or connected component identification. I discuss the suitability of different approaches of parallelization of cluster labeling and cluster update algorithms for calculations on GPU and compare to the performance of serial implementations.Comment: 15 pages, 14 figures, one table, submitted to PR

Compensation of hemispheric albedo asymmetries by shifts of the ITCZ and tropical clouds

Despite a substantial hemispheric asymmetry in clear-sky albedo, observations of Earth's radiation budget reveal that the two hemispheres have the same all-sky albedo. Here, aquaplanet simulations with the atmosphere general circulation model ECHAM6 coupled to a slab ocean are performed to study to what extent and by which mechanisms clouds compensate hemispheric asymmetries in clear-sky albedo. Clouds adapt to compensate the imposed asymmetries because the intertropical convergence zone (ITCZ) shifts into the dark surface hemisphere. The strength of this tropical compensation mechanism is linked to the magnitude of the ITCZ shift. In some cases the ITCZ shift is so strong as to overcompensate the hemispheric asymmetry in clear-sky albedo, yielding a range of climates for which the hemisphere with lower clear-sky albedo has a higher all-sky albedo. The ITCZ shift is sensitive to the convection scheme and the depth of the slab ocean. Cloud-radiative feedbacks explain part of the sensitivity to the convection scheme as they amplify the ITCZ shift in the Tiedtke (TTT) scheme but have a neutral effect in the Nordeng (TNT) scheme. A shallower slab ocean depth, and thereby reduced thermal inertia of the underlying surface and increased seasonal cycle, stabilizes the ITCZ against annual-mean shifts. The results lend support to the idea that the climate system adjusts so as to minimize hemispheric albedo asymmetries, although there is no indication that the hemispheres must have exactly the same albedo. © 2014 American Meteorological Society

LABA/LAMA combinations versus LAMA monotherapy or LABA/ICS in COPD : a systematic review and meta-analysis

Acknowledgments The meta-analysis work was performed by Guruprasad Rao KS and Sharanbasappa Durg of Molecular Connections (P) Ltd, Bangalore, India, under the guidance of the manuscript authors and Novartis Pharma AG (Basel, Switzerland). Medical writing assistance was provided by Colette O’Sullivan, PhD, of Scriva Medical Communications Ltd, a professional medical writer funded by Novartis. Development of the manuscript was supported by Novartis Pharma AG (Basel, Switzerland). The authors received no compensation related to the development of the manuscript.Peer reviewedPublisher PD

Development of a new laser Doppler velocimeter for the Ames High Reynolds Channel No. 2

A new two-channel laser Doppler velocimeter developed for the Ames High Reynolds Channel No. 2 is described. Design features required for the satisfactory operation of the optical system in the channel environment are discussed. Fiber optics are used to transmit the megahertz Doppler signal to the photodetectors located outside the channel pressure vessel, and provision is made to isolate the optical system from pressure and thermal strain effects. Computer-controlled scanning mirrors are used to position the laser beams in the channel flow. Techniques used to seed the flow with 0.5-micron-diam polystyrene spheres avoiding deposition on the test-section windows and porous boundary-layer removal panels are described. Preliminary results are presented with a discussion of several of the factors affecting accuracy