4,131 research outputs found
Magnetic microcompressor
Issued as final reportVirtual Aerosurface Technologie
Exit plane H2O concentration measurements correlated with OH PLIF near-injector mixing measurements for scramjet flows
Mixing and combusting high enthalpy flows, similar to those encountered in scramjet engines, were investigated using a shock tunnel to produce the flow in conjunction with non-intrusive optical diagnostics which monitored the performance of two injector configurations. The shock tunnel is configured to produce Mach 3 flow and stagnation enthalpies corresponding to flight equivalent Mach numbers between 7 and 11. A pulsed hydrogen injection capability and interchangeable injector blocks provide a means of examining high speed, high enthalpy reacting flows. Planar laser induced fluorescence (PLIF) of OH molecules in the near injector region produced images which show the combusting and mixing zones for the reacting flow. Line-of-sight exit plane measurement of water concentration and temperature were used to provide a unique method of monitoring exit plane products. These results demonstrated that a velocity matched axial injection system produced a fuel jet that lifted off the floor of the duct. Mixing was observed to increase for this system as a velocity mismatch was introduced. Comparison of exit plane water concentrations for a wall jet injection system and a velocity matched injection system indicated similar mixing performance but an accurate pressure measurement is necessary to further validate the result. In addition, exit plane measurements indicated an approximate steady-state condition was achieved during the 1 to 2 ms test times
Laser Applications to Chemical and Environmental Analysis: Introduction to the Feature Issue
This issue of Applied Optics features 16 papers describing chemical and environmental measurements made possible by lasers. Many of these contributions were presented at the Optical Society of America Topical Meeting on Laser Applications to Chemical and Environmental Analysis, held in Orlando, Florida, 9–11 March 1998.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86759/1/Sick33.pd
Nitrogen and Oxygen Photochemistry following SL9
The collision of Shoemaker Levy 9 (SL9) with Jupiter caused many new molecular species to be deposited in the Jovian stratosphere. We use a photochemical model to follow the evolution of the impact derived species. Our results regarding the nitrogen and oxygen compounds are presented here. NH3 photolysis initiates the nitrogen photochemistry. Much of the nitrogen ends up in N2, nitrogen-sulfur compounds, and HCN, but NH3 and nitriles such as C2H3CN may also exist in observable quantities for a year or so after the impacts. Oxygen species survive for a long time in the Jovian stratosphere. The only major oxygen containing compounds that exhibit dramatic changes in the lower stratosphere in the first year following the impacts are SO, SO2, and OCS - H2O, CO2, and CO are comparatively stable. We discuss the important photochemical processes operating on the nitrogen and oxygen species in the Jovian stratosphere, make prediction concerning the temporal variation of the major species, and identify molecules that might act as good tracers for atmospheric dynamics
How today’s shocks predict tomorrow’s leaving
Purpose
This research explores “shocking events” as part of the unfolding model of turnover, extending our understanding of the influence of various types of shocks on future voluntary employee separations.
Design/Methodology/Approach:
1536 new hires at a large financial institution reported shocks monthly during their first 8 months at work as well as their job satisfaction and perceptions of marketability. We used event history to estimate the basic distributional properties of the shocks and Cox proportional hazards models to examine the effects of shocks on job satisfaction and turnover over the subsequent year as reported by the organization.
Findings:
Organizational shocks generally occur earlier than personal shocks. Further, unexpected shocks have a stronger impact than expected shocks on subsequent turnover. Finally, the effects of organizational shocks on turnover are mediated by job satisfaction, whereas personal shocks have direct effects on turnover.
Implications:
Our findings offer evidence for the utility of the shock construct in the unfolding model of turnover and speak to the importance of encouraging managers to monitor shocks on an ongoing basis in order to predict when different types of shocks will occur and their likely influence on turnover.
Originality/Value:
Ours is the first study to examine shocks as they occur. This is a contrast to prior studies that relied on retrospective accounts. Thus, we are able to test new hypotheses (e.g., direct effects vs. mediation) that expand the unfolding model of turnover
Improving Software Citation and Credit
The past year has seen movement on several fronts for improving software
citation, including the Center for Open Science's Transparency and Openness
Promotion (TOP) Guidelines, the Software Publishing Special Interest Group that
was started at January's AAS meeting in Seattle at the request of that
organization's Working Group on Astronomical Software, a Sloan-sponsored
meeting at GitHub in San Francisco to begin work on a cohesive research
software citation-enabling platform, the work of Force11 to "transform and
improve" research communication, and WSSSPE's ongoing efforts that include
software publication, citation, credit, and sustainability.
Brief reports on these efforts were shared at the BoF, after which
participants discussed ideas for improving software citation, generating a list
of recommendations to the community of software authors, journal publishers,
ADS, and research authors. The discussion, recommendations, and feedback will
help form recommendations for software citation to those publishers represented
in the Software Publishing Special Interest Group and the broader community.Comment: Birds of a Feather session organized by the Astrophysics Source Code
Library (ASCL, http://ascl.net/ ); to be published in Proceedings of ADASS
XXV (Sydney, Australia; October, 2015). 4 page
Fcc-bcc transition for Yukawa interactions determined by applied strain deformation
Calculations of the work required to transform between bcc and fcc phases
yield a high-precision bcc-fcc transition line for monodisperse point Yukawa
(screened-Couloumb) systems. Our results agree qualitatively but not
quantitatively with previously published simulations and phenomenological
criteria for the bcc-fcc transition. In particular, the bcc-fcc-fluid triple
point lies at a higher inverse screening length than previously reported.Comment: RevTex4, 9 pages, 6 figures. Discussion of phase coexistence
extended, a few other minor clarifications added, referencing improved.
Accepted for publication by Physical Review
The MAPPINGS III Library of Fast Radiative Shock Models
We present a new library of fully-radiative shock models calculated with the
MAPPINGS III shock and photoionization code. The library consists of grids of
models with shock velocities in the range v=100-1000 km/s and magnetic
parameters B/sqrt(n) of 10^-4 - 10 muG cm^(3/2) for five different atomic
abundance sets, and for a pre-shock density of 1.0 cm^(-3). Additionally, Solar
abundance model grids have been calculated for densities of 0.01, 0.1, 10, 100,
and 1000 cm^(-3) with the same range in v and B/sqrt(n). Each model includes
components of both the radiative shock and its photoionized precursor, ionized
by the EUV and soft X-ray radiation generated in the radiative gas. We present
the details of the ionization structure, the column densities, and the
luminosities of the shock and its precursor. Emission line ratio predictions
are separately given for the shock and its precursor as well as for the
composite shock+precursor structure to facilitate comparison with observations
in cases where the shock and its precursor are not resolved. Emission line
ratio grids for shock and shock+precursor are presented on standard line ratio
diagnostic diagrams, and we compare these grids to observations of radio
galaxies and a sample of AGN and star forming galaxies from the Sloan Digital
Sky Survey. This library is available online, along with a suite of tools to
enable the analysis of the shocks and the easy creation of emission line ratio
diagnostic diagrams. These models represent a significant increase in parameter
space coverage over previously available models, and therefore provide a unique
tool in the diagnosis of emission by shocks.Comment: 39 pages, 34 figures, accepted for publication in ApJS, April 200
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