28,898 research outputs found
Wind energy system time-domain (WEST) analyzers
A portable analyzer which simulates in real time the complex nonlinear dynamics of horizontal axis wind energy systems was constructed. Math models for an aeroelastic rotor featuring nonlinear aerodynamic and inertial terms were implemented with high speed digital controllers and analog calculation. This model was combined with other math models of elastic supports, control systems, a power train and gimballed rotor kinematics. A stroboscopic display system graphically depicting distributed blade loads, motion, and other aerodynamic functions on a cathode ray tube is included. Limited correlation efforts showed good comparison between the results of this analyzer and other sophisticated digital simulations. The digital simulation results were successfully correlated with test data
Pyrotechnic shock analysis and testing methods
Pyrotechnic shock analysis and testing methods for Ranger and Mariner spacecraft measurement
Measuring the Influence of Commodity Fund Trading on Soybean Price Discovery
The increase in commodity fund trading in the agricultural commodity futures markets has raised concern that this trading is degrading the price discovery performance of these markets. We used the Beveridge-Nelson Decomposition procedure to estimate the price discovery performance of the soybean futures and spot markets. We found that the price discovery performance of the soybean futures market has improved along with the increased commodity fund trading. Our results indicated that a portion of the price discovered in the soybean futures market is passed to the spot market.price discovery, commodity funds, cointegration, Beveridge-Nelson decomposition,
Nuclear Aspects of Nucleosynthesis in Massive Stars
Preliminary results of a new set of stellar evolution and nucleosynthesis
calculations for massive stars are presented. These results were obtained with
an extended reaction network up to Bi. The discussion focuses on the importance
of nuclear rates in pre- and post-explosive nucleosynthesis. The need for
further experiments to study specific reactions and nuclear properties (optical
alpha+nucleus potentials) is emphasized.Comment: 6 pages, 2 figures; invited talk, to appear in the Proceedings of the
Int. Conf. "Structure of the Nucleus at the Dawn of the Century", May 2000,
Bologna, Ital
Nucleosynthesis in massive stars revisited
We have performed the first calculations to follow the evolution of all
stable nuclei and their radioactive progenitors in a finely-zoned stellar model
computed from the onset of central hydrogen burning through explosion as a Type
II supernova. Calculations were done for 15, 20, and 25 solar masses Pop I
stars using the most recently available set of experimental and theoretical
nuclear data, revised opacity tables, and taking into account mass loss due to
stellar winds. Here results are presented for one 15 solar masses model.Comment: 4 pages, 1 figure; needs espcrc1.sty; talk at "Nuclei in the Cosmos
2000", Aarhus, Denmark, June 2000; will appear in Nucl. Phys.
A terminal guidance scheme for lifting body entry vehicles
Perturbation feedback guidance for terminal phase of lifting body entry vehicl
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