548 research outputs found
Tests on welded high strength steel plate girders subjected to shear
An earlier project report presented a theoretical determination of the ultimate strength of plate girders subjected to shear. To investigate the shear strength of plate girders experimentally, a series of tests were conducted
The temporally evolving energy and waiting time statistics of two repeating fast radio bursts
Based on two very large samples of repeating fast radio bursts (FRBs), i.e.
FRB 20121102A and FRB 20201124A observed by the FAST telescope, we study the
statistical properties of energy and waiting time. The bent power-law (BPL)
model, thresholded power-law (TPL) model and Band function are used to fit the
distribution of energy, and the BPL model and exponential (EXP) model are used
to fit the distribution of waiting time. It is found that no single model can
fit the distribution of energy or waiting time well in the full range. To
investigate the possible temporal evolution, we divide the full samples into
several subsamples according to the observing sessions. We find that the
distribution of energy for all subsamples can be well fitted by both BPL model
and TPL model, while the distribution of waiting time for all subsamples can be
well fitted by both BPL model and EXP model. Importantly, for the distribution
of energy, the BPL index of all the subsamples is almost invariant, but
the median value parameter varies significantly. Similar situation
happens in the distribution of waiting time. Furthermore, for the distribution
of waiting time, the occurrence rate parameter in EXP model varies
significantly. These features show that there may be a common emission
mechanism for repeating FRBs, but the burst energy and occurrence rate are
temporally evolving.Comment: 12 pages, 8 figures, 4 tables; accepted for publication in Monthly
Notices of the Royal Astronomical Societ
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