10,285 research outputs found
Testing the bus guardian unit of the FTMP
Fault-tolerant multiprocessor (FTMP) operation is discussed. Fault-modeling in the bus guardian units (BGUs) is covered. Testing the BGU is discussed. A testing algorithm is proposed
Coherent control of atomic excitation using off-resonant strong few-cycle pulses
We study the dynamics of a two-level system driven by an off-resonant
few-cycle pulse which has a phase jump at , in contrast to many
cycle pulses, under non rotating-wave approximation (NRWA). We give a closed
form analytical solution for the evolution of the probability amplitude for the upper level. Using the appropriate pulse parameters like
phase-jump , jump time , pulse width , frequency and
Rabi frequency the population transfer, after the pulse is gone,
can be optimized and for the pulse considered here, enhancement of
factor was obtained.Comment: 5 Pages, 7 Figure
Aircraft control via variable cant-angle winglets
Copyright @ 2008 American Institute of Aeronautics and AstronauticsThis paper investigates a novel method for the control of "morphing" aircraft. The concept consists of a pair of winglets; with adjustable cant angle, independently actuated and mounted at the tips of a baseline flying wing. The general philosophy behind the concept was that for specific flight conditions such as a coordinated turn, the use of two control devices would be sufficient for adequate control. Computations with a vortex lattice model and subsequent wind-tunnel tests demonstrate the viability of the concept, with individual and/or dual winglet deflection producing multi-axis coupled control moments. Comparisons between the experimental and computational results showed reasonable to good agreement, with the major discrepancies thought to be due to wind-tunnel model aeroelastic effects.This work has been supported by a Marie Curie excellence research grant funded by the European Commission
Optical Spectroscopy of Type Ia Supernovae
We present 432 low-dispersion optical spectra of 32 Type Ia supernovae (SNe
Ia) that also have well-calibrated light curves. The coverage ranges from 6
epochs to 36 epochs of spectroscopy. Most of the data were obtained with the
1.5m Tillinghast telescope at the F. L. Whipple Observatory with typical
wavelength coverage of 3700-7400A and a resolution of ~7A. The earliest spectra
are thirteen days before B-band maximum; two-thirds of the SNe were observed
before maximum brightness. Coverage for some SNe continues almost to the
nebular phase. The consistency of the method of observation and the technique
of reduction makes this an ideal data set for studying the spectroscopic
diversity of SNe Ia.Comment: Accepted for publication in the Astronomical Journal, 109 pages
(including data table), 44 figures, full resolution figures at
http://www.noao.edu/noao/staff/matheson/Iaspec.ps.g
- …