17,671 research outputs found
Pre-flare coronal dimmings
In this paper, we focus on the pre-flare coronal dimmings. We report our
multiwavelength observations of the GOES X1.6 solar flare and the accompanying
halo CME produced by the eruption of a sigmoidal magnetic flux rope (MFR) in
NOAA active region (AR) 12158 on 2014 September 10. The eruption was observed
by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamic Observatory
(SDO). The photospheric line-of-sight magnetograms were observed by the
Helioseismic and Magnetic Imager (HMI) aboard SDO. The soft X-ray (SXR) fluxes
were recorded by the GOES spacecraft. The halo CME was observed by the white
light coronagraphs of the Large Angle Spectroscopic Coronagraph (LASCO) aboard
SOHO.} {About 96 minutes before the onset of flare/CME, narrow pre-flare
coronal dimmings appeared at the two ends of the twisted MFR. They extended
very slowly with their intensities decreasing with time, while their apparent
widths (89 Mm) nearly kept constant. During the impulsive and decay phases
of flare, typical fanlike twin dimmings appeared and expanded with much larger
extent and lower intensities than the pre-flare dimmings. The percentage of 171
{\AA} intensity decrease reaches 40\%. The pre-flare dimmings are most striking
in 171, 193, and 211 {\AA} with formation temperatures of 0.62.5 MK. The
northern part of the pre-flare dimmings could also be recognized in 131 and 335
{\AA}.} To our knowledge, this is the first detailed study of pre-flare coronal
dimmings, which can be explained by the density depletion as a result of the
gradual expansion of the coronal loop system surrounding the MFR during the
slow rise of the MFR.Comment: 6 pages, 8 figures, to be accepted for publication by A&
On the scalar nonet in the extended Nambu Jona-Lasinio model
We discuss the lightest scalar resonances, , ,
and in the extended Nambu Jona-Lasinio model. We find
that the model parameters can be tuned, but unnaturally, to accommodate for
those scalars except the . We also discuss problems encountered in
the K Matrix unitarization approximation by using counting technique.Comment: 23 pages 3 eps figures, To appear in Nucl. Phys.
Non-damping oscillations at flaring loops
Context. QPPs are usually detected as spatial displacements of coronal loops
in imaging observations or as periodic shifts of line properties in
spectroscopic observations. They are often applied for remote diagnostics of
magnetic fields and plasma properties on the Sun. Aims. We combine imaging and
spectroscopic measurements of available space missions, and investigate the
properties of non-damping oscillations at flaring loops. Methods. We used the
IRIS to measure the spectrum over a narrow slit. The double-component Gaussian
fitting method was used to extract the line profile of Fe XXI 1354.08 A at "O
I" window. The quasi-periodicity of loop oscillations were identified in the
Fourier and wavelet spectra. Results. A periodicity at about 40 s is detected
in the line properties of Fe XXI, HXR emissions in GOES 1-8 A derivative, and
Fermi 26-50 keV. The Doppler velocity and line width oscillate in phase, while
a phase shift of about Pi/2 is detected between the Doppler velocity and peak
intensity. The amplitudes of Doppler velocity and line width oscillation are
about 2.2 km/s and 1.9 km/s, respectively, while peak intensity oscillate with
amplitude at about 3.6% of the background emission. Meanwhile, a quasi-period
of about 155 s is identified in the Doppler velocity and peak intensity of Fe
XXI, and AIA 131 A intensity. Conclusions. The oscillations at about 40 s are
not damped significantly during the observation, it might be linked to the
global kink modes of flaring loops. The periodicity at about 155 s is most
likely a signature of recurring downflows after chromospheric evaporation along
flaring loops. The magnetic field strengths of the flaring loops are estimated
to be about 120-170 G using the MHD seismology diagnostics, which are
consistent with the magnetic field modeling results using the flux rope
insertion method.Comment: 9 pages, 9 figures, 1 table, accepted by A&
Excitation Energy as a Basic Variable to Control Nuclear Disassembly
Thermodynamical features of Xe system is investigated as functions of
temperature and freeze-out density in the frame of lattice gas model. The
calculation shows different temperature dependence of physical observables at
different freeze-out density. In this case, the critical temperature when the
phase transition takes place depends on the freeze-out density. However, a
unique critical excitation energy reveals regardless of freeze-out density when
the excitation energy is used as a variable insteading of temperature.
Moreover, the different behavior of other physical observables with temperature
due to different vanishes when excitation energy replaces temperature.
It indicates that the excitation energy can be seen as a more basic quantity to
control nuclear disassembly.Comment: 3 pages, 2 figures, Revte
Advantage of low quality in short life cycle products
This study explores the factors influencing customers’ purchase intention for low quality products. The traditional thinking is that products with high quality and low price will win more customers. However, we can notice that high quality products usually have high cost. Therefore, it is necessary to do more research on how customers can accept low quality products, in order to and help companies to win more customers and market share. We take fast fashion products and smart phones as empirical studies, collecting data from customer’s online survey. Based on the methodology of fuzzy-set qualitative comparative analysis (fsQCA), we analyses the relationship between the factors of short lifecycle, low quality, design and price and influence customer purchase intention. It shows that the product price and design are major driving factors for customers to accept low quality products. The result has implications for other industries that sell products with low cost
Large-scale customized indemnificatory housing area system design: Shenzhen 2011 "1unit - 100families - 10000residents" comprehensive gold award program in indemnificatory housing design contest: E-dot
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