32,978 research outputs found
Cohen-Macaulay graphs and face vectors of flag complexes
We introduce a construction on a flag complex that, by means of modifying the
associated graph, generates a new flag complex whose -factor is the face
vector of the original complex. This construction yields a vertex-decomposable,
hence Cohen-Macaulay, complex. From this we get a (non-numerical)
characterisation of the face vectors of flag complexes and deduce also that the
face vector of a flag complex is the -vector of some vertex-decomposable
flag complex. We conjecture that the converse of the latter is true and prove
this, by means of an explicit construction, for -vectors of Cohen-Macaulay
flag complexes arising from bipartite graphs. We also give several new
characterisations of bipartite graphs with Cohen-Macaulay or Buchsbaum
independence complexes.Comment: 14 pages, 3 figures; major updat
International Ultraviolet Explorer (IUE) satellite mission analysis
The results are presented of the mission analysis performed by Computer Sciences Corporation (CSC) in support of the International Ultraviolet Explorer (IUE) satellite. The launch window is open for three separate periods (for a total time of 7 months) during the year extending from July 20, 1977, to July 20, 1978. The synchronous orbit shadow constraint limits the launch window to approximately 88 minutes per day. Apogee boost motor fuel was computed to be 455 pounds (206 kilograms) and on-station weight was 931 pounds (422 kilograms). The target orbit is elliptical synchronous, with eccentricity 0.272 and 24 hour period
Using rewards and penalties to obtain desired subject performance
Operant conditioning procedures, specifically the use of negative reinforcement, in achieving stable learning behavior is described. The critical tracking test (CTT) a method of detecting human operator impairment was tested. A pass level is set for each subject, based on that subject's asymptotic skill level while sober. It is critical that complete training take place before the individualized pass level is set in order that the impairment can be detected. The results provide a more general basis for the application of reward/penalty structures in manual control research
Analysis of the Learjet 35/36 Wing and Correlation with Experimental Results
Two NASTRAN models of the Gates Learjet Corporation Model 35/36 Wing were developed. The models and the problems encountered in their development are discussed. A skin buckling analysis used for the ultimate loading conditions is presented. A discussion of the static tests and the correlation of the static test with the NASTRAN results and the results of a supplementary semimonocoque beam analysis are also included
Exotic Meson Decay Widths using Lattice QCD
A decay width calculation for a hybrid exotic meson h, with JPC=1-+, is
presented for the channel h->pi+a1. This quenched lattice QCD simulation
employs Luescher's finite box method. Operators coupling to the h and pi+a1
states are used at various levels of smearing and fuzzing, and at four quark
masses. Eigenvalues of the corresponding correlation matrices yield energy
spectra that determine scattering phase shifts for a discrete set of relative
pi+a1 momenta. Although the phase shift data is sparse, fits to a Breit-Wigner
model are attempted, resulting in a decay width of about 60 MeV when averaged
over two lattice sizes.Comment: 9 pages, 8 figures, RevTex4, minor change to Fig.
Preliminary Abundance Analysis of Galactic Bulge Main Sequence, Subgiant, and Giant Branch Stars Observed During Microlensing with Keck/HIRES
We present an abundance analysis of six main sequence turnoff, subgiant, and
giant branch stars toward the Galactic bulge that were observed with Keck/HIRES
during microlensing events. This is an early look at the first detailed
chemical analysis of main sequence stars in the Galactic bulge. Lensing events
allow the effective aperture of Keck to be increased beyond its current
dimensions; although, some events still stretched its spectroscopic
capabilities. Future large telescopes with high resolution and high throughput
spectrometers will allow the study of abundances in distant stellar populations
and in less evolved stars with greater ease.Comment: 8 pages including 2 figures. To appear in SPIE proceedings on
Astronomical Telescopes and Instrumentation. Uses spie.cl
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