2,875 research outputs found
Necessary Condition for Near Optimal Control of Linear Forward-backward Stochastic Differential Equations
This paper investigates the near optimal control for a kind of linear
stochastic control systems governed by the forward backward stochastic
differential equations, where both the drift and diffusion terms are allowed to
depend on controls and the control domain is not assumed to be convex. In the
previous work (Theorem 3.1) of the second and third authors [\textit{%
Automatica} \textbf{46} (2010) 397-404], some problem of near optimal control
with the control dependent diffusion is addressed and our current paper can be
viewed as some direct response to it. The necessary condition of the
near-optimality is established within the framework of optimality variational
principle developed by Yong [\textit{SIAM J. Control Optim.} \textbf{48} (2010)
4119--4156] and obtained by the convergence technique to treat the optimal
control of FBSDEs in unbounded control domains by Wu [% \textit{Automatica}
\textbf{49} (2013) 1473--1480]. Some new estimates are given here to handle the
near optimality. In addition, an illustrating example is discussed as well.Comment: To appear in International Journal of Contro
Tunable Intrinsic Plasmons due to Band Inversion in Topological Materials
The band inversion has led to rich physical effects in both topological
insulators and topological semimetals. It has been found that the inverted band
structure with the Mexican-hat dispersion could enhance the interband
correlation leading to a strong intrinsic plasmon excitation. Its frequency
ranges from several to tens of and can be
effectively tuned by the external fields. The electron-hole asymmetric term
splits the peak of the plasmon excitation into double peaks. The fate and
properties of this plasmon excitation can also act as a probe to characterize
the topological phases even in the lightly doped systems. We numerically
demonstrate the impact of the band inversion on plasmon excitations in
magnetically doped thin films of three-dimensional strong topological
insulators, V- or Cr-doped (Bi, Sb)Te, which support the quantum
anomalous Hall states. Our work thus sheds some new light on the potential
applications of topological materials in plasmonics.Comment: 6 pages, 5 figures, Accepted in PR
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