3,294 research outputs found
Which Surrogate Works for Empirical Performance Modelling? A Case Study with Differential Evolution
It is not uncommon that meta-heuristic algorithms contain some intrinsic
parameters, the optimal configuration of which is crucial for achieving their
peak performance. However, evaluating the effectiveness of a configuration is
expensive, as it involves many costly runs of the target algorithm. Perhaps
surprisingly, it is possible to build a cheap-to-evaluate surrogate that models
the algorithm's empirical performance as a function of its parameters. Such
surrogates constitute an important building block for understanding algorithm
performance, algorithm portfolio/selection, and the automatic algorithm
configuration. In principle, many off-the-shelf machine learning techniques can
be used to build surrogates. In this paper, we take the differential evolution
(DE) as the baseline algorithm for proof-of-concept study. Regression models
are trained to model the DE's empirical performance given a parameter
configuration. In particular, we evaluate and compare four popular regression
algorithms both in terms of how well they predict the empirical performance
with respect to a particular parameter configuration, and also how well they
approximate the parameter versus the empirical performance landscapes
Low-lying charmed and charmed-strange baryon states
In this work, we systematically study the mass spectra and strong decays of
and charmed and charmed-strange baryons in the framework of
nonrelativistic constituent quark models. With the light quark cluster-heavy
quark picture, the masses are simply calculated by a potential model. The
strong decays are studied by the Eichten-Hill-Quigg decay formula. Masses and
decay properties of the well-established and states can be reproduced
by our method. can be assigned as a
or state. We prefer to interpret the
signal as a state although at present we cannot
thoroughly exclude the possibility that this is the same state as
. or could be
explained as the state or state,
respectively. We propose to measure the branching ratio of
in future,
which may disentangle the puzzle of this state. Our results support
as the first radial excited state of
with . The assignment of is analogous to
, \emph{i.e.}, a or
state. In addition, we predict some typical ratios
among partial decay widths, which are valuable for experimental search for
these missing charmed and charmed-strange baryons.Comment: 16 pages, 3 figures, 13 tables. Accepted by Eur. Phys. J.
A high order unfitted finite element method for time-Harmonic Maxwell interface problems
In this paper, we propose a high order unfitted finite element method for
solving time-harmonic Maxwell interface problems. The unfitted finite element
method is based on a mixed formulation in the discontinuous Galerkin framework
on a Cartesian mesh with possible hanging nodes. The regularity of the
solution to Maxwell interface problems with interfaces in each subdomain
is proved. Practical interface resolving mesh conditions are introduced under
which the hp inverse estimates on three-dimensional curved domains are proved.
Stability and hp a priori error estimate of the unfitted finite element method
are proved. Numerical results are included to illustrate the performance of the
method
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