20,914 research outputs found
Alternatives with stronger convergence than coordinate-descent iterative LMI algorithms
In this note we aim at putting more emphasis on the fact that trying to solve
non-convex optimization problems with coordinate-descent iterative linear
matrix inequality algorithms leads to suboptimal solutions, and put forward
other optimization methods better equipped to deal with such problems (having
theoretical convergence guarantees and/or being more efficient in practice).
This fact, already outlined at several places in the literature, still appears
to be disregarded by a sizable part of the systems and control community. Thus,
main elements on this issue and better optimization alternatives are presented
and illustrated by means of an example.Comment: 3 pages. Main experimental results reproducible from files available
on http://www.mathworks.com/matlabcentral/fileexchange/33219 This work has
been submitted to the IEEE for possible publication. Copyright may be
transferred without notice, after which this version may no longer be
accessibl
Lorentz invariance violation and charge (non--)conservation: A general theoretical frame for extensions of the Maxwell equations
All quantum gravity approaches lead to small modifications in the standard
laws of physics which lead to violations of Lorentz invariance. One particular
example is the extended standard model (SME). Here, a general phenomenological
approach for extensions of the Maxwell equations is presented which turns out
to be more general than the SME and which covers charge non--conservation
(CNC), too. The new Lorentz invariance violating terms cannot be probed by
optical experiments but need, instead, the exploration of the electromagnetic
field created by a point charge or a magnetic dipole. Some scalar--tensor
theories and higher dimensional brane theories predict CNC in four dimensions
and some models violating Special Relativity have been shown to be connected
with CNC and its relation to the Einstein Equivalence Principle has been
discussed. Due to this upcoming interest, the experimental status of electric
charge conservation is reviewed. Up to now there seem to exist no unique tests
of charge conservation. CNC is related to the precession of polarization, to a
modification of the --Coulomb potential, and to a time-dependence of the
fine structure constant. This gives the opportunity to describe a dedicated
search for CNC.Comment: To appear in Physical Review
Exploring Language-Independent Emotional Acoustic Features via Feature Selection
We propose a novel feature selection strategy to discover
language-independent acoustic features that tend to be responsible for emotions
regardless of languages, linguistics and other factors. Experimental results
suggest that the language-independent feature subset discovered yields the
performance comparable to the full feature set on various emotional speech
corpora.Comment: 15 pages, 2 figures, 6 table
- …