513,491 research outputs found
Does a low solar cycle minimum hint at a weak upcoming cycle?
The maximum amplitude (Rm) of a solar cycle, in the term of mean sunspot
numbers, is well-known to be positively correlated with the preceding minimum
(Rmin). So far as the long term trend is concerned, a low level of Rmin tends
to be followed by a weak Rm, and vice versa. In this paper, we found that the
evidence is insufficient to infer a very weak Cycle 24 from the very low Rmin
in the preceding cycle. This is concluded by analyzing the correlation in the
temporal variations of parameters for two successive cycles.Comment: 5 pages, 2 figures. Accepted by RA
On solvability of an indefinite Riccati equation
This note concerns a class of matrix Riccati equations associated with
stochastic linear-quadratic optimal control problems with indefinite state and
control weighting costs. A novel sufficient condition of solvability of such
equations is derived, based on a monotonicity property of a newly defined set.
Such a set is used to describe a family of solvable equations.Comment: 11 page
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