4,198 research outputs found
Two Step Filament Eruption During 14-15 March 2015
We present here an interesting two-step filament eruption during 14-15 March
2015. The filament was located in NOAA AR 12297 and associated with a halo
Coronal Mass Ejection (CME). We use observations from the Atmospheric Imaging
Assembly (AIA) and Heliospheric Magnetic Imager (HMI) instruments onboard the
Solar Dynamics Observatory (SDO), and from the Solar and Heliospheric
Observatory (SOHO) Large Angle and Spectrometric Coronagraph (LASCO). We also
use H-alpha data from the Global Oscillation Network Group (GONG) telescope and
the Kanzelhoehe Solar Observatory. The filament shows a first step eruption on
14 March 2015 and it stops its rise at a projected altitude ~ 125 Mm on the
solar disk. It remains at this height for ~ 12 hrs. Finally it eruptes on 15
March 2015 and produced a halo CME. We also find jet activity in the active
region during both days, which could help the filament de-stabilization and
eruption. The decay index is calculated to understand this two-step eruption.
The eruption could be due to the presence of successive
instability-stability-instability zones as the filament is rising.Comment: 11 pages, 7 figures, accepted for the publication in Solar Physic
Optimal Design of Stiffened Cylindrical Shells Based on an Asymptotic Approach
The linear differential equations describing the free vibrations of ring-stiffened thin cylindrical shells are solved with the help of asymptotic techniques. The received approximate formulas are used for the evaluation of optimal parameters corresponding to the maximal fundamental frequency of the ring-stiffened shell with given mass
Quantum Fluctuations in Josephson Junction Comparators
We have developed a method for calculation of quantum fluctuation effects, in
particular of the uncertainty zone developing at the potential curvature sign
inversion, for a damped harmonic oscillator with arbitrary time dependence of
frequency and for arbitrary temperature, within the Caldeira-Leggett model. The
method has been applied to the calculation of the gray zone width Delta Ix of
Josephson-junction balanced comparators driven by a specially designed
low-impedance RSFQ circuit. The calculated temperature dependence of Delta Ix
in the range 1.5 to 4.2K is in a virtually perfect agreement with experimental
data for Nb-trilayer comparators with critical current densities of 1.0 and 5.5
kA/cm^2, without any fitting parameters.Comment: 4 pages, 4 figures, submitted to Physical Review Letter
Wire GEM detector
A wire GEM (WGEM) detector with a gas gap between meshes was constructed. The
detector provides the amplification 5x10E5 for the gas mixture of Ar +20% CO2
at atmospheric pressure. As compared with well-known GEM detectors produced by
perforation the plastic plate metalized on both sides the WGEM does not suffer
from breakdowns between its electrodes and the effect of accumulation of
charges on holes walls is absent. As a result the WGEM has high reliability and
stability.Comment: Presented at the RD51 Collaboration Meeting, CERN, November 2009,
submitted to the Prib. Tech. Expe
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