25,505 research outputs found
Observations of Early Optical Afterglows
The Swift Ultra-Violet/Optical Telescope (UVOT) has performed extensive
follow-up on 71 Swift Burst Alert Telescope triggered gamma-ray bursts (GRBs)
in its first ten months of operations. In this paper, we discuss some of the UV
and optical properties of UVOT detected afterglows such as XRF 050406, the
bright GRB 050525A, the high redshift GRB 050730, the early flaring GRB 050801,
and others. We also discuss some of the implications of why 75% of GRB
afterglows observed by UVOT in less than one hour are "dark."Comment: 10 pages, 6 figures, to appear in the Proceedings of the 16th Annual
Astrophysics Conference in Maryland "Gamma Ray Bursts in the Swift Era,"
Washington, DC, November 29 - December 2, 200
Development of technology for modeling of a 1/8-scale dynamic model of the shuttle Solid Rocket Booster (SRB)
A NASTRAN analysis of the solid rocket booster (SRB) substructure of the space shuttle 1/8-scale structural dynamics model. The NASTRAN finite element modeling capability was first used to formulate a model of a cylinder 10 in. radius by a 200 in. length to investigate the accuracy and adequacy of the proposed grid point spacing. Results were compared with a shell analysis and demonstrated relatively accurate results for NASTRAN for the lower modes, which were of primary interest. A finite element model of the full SRB was then formed using CQUAD2 plate elements containing membrane and bending stiffness and CBAR offset bar elements to represent the longerons and frames. Three layers of three-dimensional CHEXAI elements were used to model the propellant. This model, consisting of 4000 degrees of freedom (DOF) initially, was reduced to 176 DOF using Guyan reduction. The model was then submitted for complex Eigenvalue analysis. After experiencing considerable difficulty with attempts to run the complete model, it was split into two substructres. These were run separately and combined into a single 116 degree of freedom A set which was successfully run. Results are reported
EC808 Cost of Producing Corn : Fillmore and Saunders Counties
Extension Circular 808 Explains and illustrates the cost of producing corn
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