5,327 research outputs found
Time-and event-driven communication process for networked control systems: A survey
Copyright © 2014 Lei Zou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.In recent years, theoretical and practical research topics on networked control systems (NCSs) have gained an increasing interest from many researchers in a variety of disciplines owing to the extensive applications of NCSs in practice. In particular, an urgent need has arisen to understand the effects of communication processes on system performances. Sampling and protocol are two fundamental aspects of a communication process which have attracted a great deal of research attention. Most research focus has been on the analysis and control of dynamical behaviors under certain sampling procedures and communication protocols. In this paper, we aim to survey some recent advances on the analysis and synthesis issues of NCSs with different sampling procedures (time-and event-driven sampling) and protocols (static and dynamic protocols). First, these sampling procedures and protocols are introduced in detail according to their engineering backgrounds as well as dynamic natures. Then, the developments of the stabilization, control, and filtering problems are systematically reviewed and discussed in great detail. Finally, we conclude the paper by outlining future research challenges for analysis and synthesis problems of NCSs with different communication processes.This work was supported in part by the National Natural Science Foundation of China under Grants 61329301, 61374127, and 61374010, the Royal Society of the UK, and the Alexander von Humboldt Foundation of Germany
Intermingled basins in coupled Lorenz systems
We consider a system of two identical linearly coupled Lorenz oscillators,
presenting synchro- nization of chaotic motion for a specified range of the
coupling strength. We verify the existence of global synchronization and
antisynchronization attractors with intermingled basins of attraction, such
that the basin of one attractor is riddled with holes belonging to the basin of
the other attractor and vice versa. We investigated this phenomenon by
verifying the fulfillment of the mathematical requirements for intermingled
basins, and also obtained scaling laws that characterize quantitatively the
riddling of both basins for this system
Kepler-413b: a slightly misaligned, Neptune-size transiting circumbinary planet
We report the discovery of a transiting, Rp = 4.347+/-0.099REarth,
circumbinary planet (CBP) orbiting the Kepler K+M Eclipsing Binary (EB) system
KIC 12351927 (Kepler-413) every ~66 days on an eccentric orbit with ap =
0.355+/-0.002AU, ep = 0.118+/-0.002. The two stars, with MA =
0.820+/-0.015MSun, RA = 0.776+/-0.009RSun and MB = 0.542+/-0.008MSun, RB =
0.484+/-0.024RSun respectively revolve around each other every
10.11615+/-0.00001 days on a nearly circular (eEB = 0.037+/-0.002) orbit. The
orbital plane of the EB is slightly inclined to the line of sight (iEB =
87.33+/-0.06 degrees) while that of the planet is inclined by ~2.5 degrees to
the binary plane at the reference epoch. Orbital precession with a period of
~11 years causes the inclination of the latter to the sky plane to continuously
change. As a result, the planet often fails to transit the primary star at
inferior conjunction, causing stretches of hundreds of days with no transits
(corresponding to multiple planetary orbital periods). We predict that the next
transit will not occur until 2020. The orbital configuration of the system
places the planet slightly closer to its host stars than the inner edge of the
extended habitable zone. Additionally, the orbital configuration of the system
is such that the CBP may experience Cassini-States dynamics under the influence
of the EB, in which the planet's obliquity precesses with a rate comparable to
its orbital precession. Depending on the angular precession frequency of the
CBP, it could potentially undergo obliquity fluctuations of dozens of degrees
(and complex seasonal cycles) on precession timescales.Comment: 48 pages, 13 figure
Trojan pairs in the HD 128311 and HD 82943 planetary systems?
Two nearby stars, HD 128311 and HD 82943, are believed to host pairs of
Jupiter-like planets involved in a strong first order 2:1 mean motion resonance
(MMR). In this work we reanalyze available radial velocity (RV) measurements
and demonstrate that it is also possible to explain the observed RV variations
of the parents stars as being induced by a pair of Trojan planets (i.e., in a
1:1 MMR). We show that these Trojan configurations reside in extended zones of
stability in which such systems may easily survive in spite of large masses of
the planets, large eccentricities and nonzero mutual inclinations of their
orbits. We also show that HD 82943 could harbor a previously unknown third
planet about of 0.5 Jupiter masses in 2.1 AU orbit.Comment: 18 pages (total), 17 figures in low resolution format suitable for
arXiv, revised version resubmitted to ApJ. The preprint with high resolution
images is available from
http://www.astri.uni.torun.pl/~chris/astroph.0510109v2.ps.g
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