539 research outputs found
G-band and Hard X-ray Emissions of the 2006 December 14 flare observed by Hinode/SOT and RHESSI
We report on G-band emission observed by the Solar Optical Telescope onboard
the Hinode satellite in association with the X1.5-class flare on 2006 December
14. The G-band enhancements originate from the footpoints of flaring coronal
magnetic loops, coinciding with non-thermal hard X-ray bremsstrahlung sources
observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager. At the
available 2 minute cadence, the G-band and hard X-ray intensities are
furthermore well correlated in time. Assuming that the G-band enhancements are
continuum emission from a blackbody, we derived the total radiative losses of
the white-light flare (white-light power). If the G-band enhancements
additionally have a contribution from lines, the derived values are
overestimates. We compare the white-light power with the power in hard X-ray
producing electrons using the thick target assumption. Independent of the
cutoff energy of the accelerated electron spectrum, the white-light power and
the power of accelerated electrons are roughly proportional. Using the observed
upper limit of ~30 keV for the cutoff energy, the hard X-ray producing
electrons provide at least a factor of 2 more power than needed to produce the
white-light emission. For electrons above 40 keV, the powers roughly match for
all four of the time intervals available during the impulsive phase. Hence, the
flare-accelerated electrons contain enough energy to produce the white-light
flare emissions. The observed correlation in time, space, and power strongly
suggests that electron acceleration and white-light production in solar flares
are closely related. However, the results also call attention to the
inconsistency in apparent source heights of the hard X-ray (chromosphere) and
white-light (upper photosphere) sources.Comment: 15 pages, 7 figures, accepted for publication in Ap
Evaluation of Liquefaction Resistance by In-situ Testing and Its Application to Reliability Design
A calculation method of probability of liquefaction is proposed in this paper. The spatial variability of soil parameters for the dynamic shear strength, i.e., N-values, median grain size, fines contents, and the statistical characteristics of the earthquake frequency are considered in the analysis. The standard penetration test (SPT) is convenient to estimate the spatial variability of the dynamic shear strength and mainly used in this study. Furthermore the determination of dynamic shear strength based on Swedish weight Sounding test also introduced here, because it is the simpler test than SPT. While the statistical model of the earthquake frequency is determined based on the record of historical earthquakes. Using this method the probability of liquefaction is calculated. The sand compaction pile method is considered for the ground improvement against the liquefaction. Finally, the relationship between the sand replacement rate and the probability of liquefaction is clarified
Can High Frequency Acoustic Waves Heat the Quiet Sun Chromosphere?
We use Hinode/SOT Ca II H-line and blue continuum broadband observations to
study the presence and power of high frequency acoustic waves at high spatial
resolution. We find that there is no dominant power at small spatial scales;
the integrated power using the full resolution of Hinode (0.05'' pixels, 0.16''
resolution) is larger than the power in the data degraded to 0.5'' pixels
(TRACE pixel size) by only a factor of 1.2. At 20 mHz the ratio is 1.6.
Combining this result with the estimates of the acoustic flux based on TRACE
data of Fossum & Carlsson (2006), we conclude that the total energy flux in
acoustic waves of frequency 5-40 mHz entering the internetwork chromosphere of
the quiet Sun is less than 800 W m, inadequate to balance the radiative
losses in a static chromosphere by a factor of five.Comment: 6 pages, 8 figures, accepted for publication in PASJ (special Hinode
issue
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