11,833 research outputs found
Seam tracking performance of a Coaxial Weld Vision System and pulsed welding
This report describes a continuation of a series of tests on the Coaxial Weld Vision System at MSFC. The ability of the system to compensate for transients associated with pulsed current welding is analyzed. Using the standard image processing approach for root pass seam tracking, the system is also tested for the ability to track the toe of a previous weld bead, for tracking multiple pass weld joints. This Coaxial Weld Vision System was developed by the Ohio State University (OSU) Center for Welding Research and is a part of the Space Shuttle Main Engine Robotic Welding Development System at MSFC
Interactive solution-adaptive grid generation procedure
TURBO-AD is an interactive solution adaptive grid generation program under development. The program combines an interactive algebraic grid generation technique and a solution adaptive grid generation technique into a single interactive package. The control point form uses a sparse collection of control points to algebraically generate a field grid. This technique provides local grid control capability and is well suited to interactive work due to its speed and efficiency. A mapping from the physical domain to a parametric domain was used to improve difficulties encountered near outwardly concave boundaries in the control point technique. Therefore, all grid modifications are performed on the unit square in the parametric domain, and the new adapted grid is then mapped back to the physical domain. The grid adaption is achieved by adapting the control points to a numerical solution in the parametric domain using control sources obtained from the flow properties. Then a new modified grid is generated from the adapted control net. This process is efficient because the number of control points is much less than the number of grid points and the generation of the grid is an efficient algebraic process. TURBO-AD provides the user with both local and global controls
Spatial and Temporal Habitat Use of an Asian Elephant in Sumatra
Increasingly, habitat fragmentation caused by agricultural and human development has forced Sumatran elephants into relatively small areas, but there is little information on how elephants use these areas and thus, how habitats can be managed to sustain elephants in the future. Using a Global Positioning System (GPS) collar and a land cover map developed from TM imagery, we identified the habitats used by a wild adult female elephant (Elephas maximus sumatranus) in the Seblat Elephant Conservation Center, Bengkulu Province, Sumatra during 2007â2008. The marked elephant (and presumably her 40â60 herd mates) used a home range that contained more than expected medium canopy and open canopy land cover. Further, within the home range, closed canopy forests were used more during the day than at night. When elephants were in closed canopy forests they were most often near the forest edge vs. in the forest interior. Effective elephant conservation strategies in Sumatra need to focus on forest restoration of cleared areas and providing a forest matrix that includes various canopy types
The Replication Argument for Incompatibilism
In this paper, I articulate an argument for incompatibilism about moral responsibility and determinism. My argument comes in the form of an extended story, modeled loosely on Peter van Inwagenâs ârollback argumentâ scenario. I thus call it âthe replication argument.â As I aim to bring out, though the argument is inspired by so-called âmanipulationâ and âoriginal designâ arguments, the argument is not a version of either such argumentâand plausibly has advantages over both. The result, I believe, is a more convincing incompatibilist argument than those we have considered previously
Nucleosynthesis in Outflows from the Inner Regions of Collapsars
We consider nucleosynthesis in outflows originating from the inner regions of
viscous accretion disks formed after the collapse of a rotating massive star.
We show that wind-like outflows driven by viscous and neutrino heating can
efficiently synthesize Fe-group elements moving at near-relativistic
velocities. The mass of 56Ni synthesized and the asymptotic velocities attained
in our calculations are in accord with those inferred from observations of
SN1998bw and SN2003dh. These steady wind-like outflows are generally proton
rich, characterized by only modest entropies, and consequently synthesize
essentially nothing heavier than the Fe-group elements. We also discuss
bubble-like outflows resulting from rapid energy deposition in localized
regions near or in the accretion disk. These intermittent ejecta emerge with
low electron fraction and are a promising site for the synthesis of the A=130
r-process peak elements.Comment: 35 pages, 6 figures, added discussion of the influence of nuclear
recombination on wind dynamics, to appear in Ap
Freire re-viewed
The work of Paulo Freire is associated with themes of oppression and liberation, and his critical pedagogy is visionary in its attempts to bring about social transformation. Freire has created a theory of education that embeds these issues within social relations that center around both ideological and material domination. In this review essay, Sue Jackson explores three books: Freireâs final work Pedagogy of Indignation; Cesar Augusto Rossattoâs Engaging Paulo Freireâs Pedagogy of Possibility, which attempts to engage Freireâs pedagogy of possibility; and C.A. Bowers and Frederique Apffel-Marglinâs edited collection Re-thinking Freire, which asks readers to reconsider Freireâs work in light of globalization and environmental crises. Jackson questions the extent to which Freireâs pedagogical approaches are useful to educators as well as to âthe oppressed,â and whether challenges to re-think Freire can lead to new kinds of critical pedagogies
Optical Visualization of Radiative Recombination at Partial Dislocations in GaAs
Individual dislocations in an ultra-pure GaAs epilayer are investigated with
spatially and spectrally resolved photoluminescence imaging at 5~K. We find
that some dislocations act as strong non-radiative recombination centers, while
others are efficient radiative recombination centers. We characterize
luminescence bands in GaAs due to dislocations, stacking faults, and pairs of
stacking faults. These results indicate that low-temperature,
spatially-resolved photoluminescence imaging can be a powerful tool for
identifying luminescence bands of extended defects. This mapping could then be
used to identify extended defects in other GaAs samples solely based on
low-temperature photoluminescence spectra.Comment: 4 pages, 4 figure
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