4,047 research outputs found
Star Formation Properties in Barred Galaxies(SFB). III. Statistical Study of Bar-driven Secular Evolution using a sample of nearby barred spirals
Stellar bars are important internal drivers of secular evolution in disk
galaxies. Using a sample of nearby spiral galaxies with weak and strong bars,
we explore the relationships between the star formation feature and stellar
bars in galaxies. We find that galaxies with weak bars tend to be coincide with
low concentrical star formation activity, while those with strong bars show a
large scatter in the distribution of star formation activity. We find enhanced
star formation activity in bulges towards stronger bars, although not
predominantly, consistent with previous studies. Our results suggest that
different stages of the secular process and many other factors may contribute
to the complexity of the secular evolution. In addition, barred galaxies with
intense star formation in bars tend to have active star formation in their
bulges and disks, and bulges have higher star formation densities than bars and
disks, indicating the evolutionary effects of bars. We then derived a possible
criterion to quantify the different stages of bar-driven physical process,
while future work is needed because of the uncertainties.Comment: 30 single-column pages, 9 figures, accepted for publication in A
Robust Average Formation Tracking for Multi-Agent Systems With Multiple Leaders
In this paper, the formation tracking problem of the multi-agent system under disturbances and unmodeled uncertainties has been studied. An identifier-based robust control algorithm using the neighboring relative information has been proposed to ensure the followers to maintain a given, and time-varying formation and track the average state of the leaders at the same time. Some sufficient conditions for the second-order multi-agent system with multiple leaders in the presence of disturbances and unmodeled uncertainties have been proposed based on the graph theory and the Lyapunov method. Numerical simulations are provided to testify the validity of the algorithm
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