12,015 research outputs found
Stabilization over power-constrained parallel Gaussian channels
This technical note is concerned with state-feedback stabilization of multi-input systems over parallel Gaussian channels subject to a total power constraint. Both continuous-time and discrete-time systems are treated under the framework of H2 control, and necessary/sufficient conditions for stabilizability are established in terms of inequalities involving unstable plant poles, transmitted power, and noise variances. These results are further used to clarify the relationship between channel capacity and stabilizability. Compared to single-input systems, a range of technical issues arise. In particular, in the multi-input case, the optimal controller has a separation structure, and the lower bound on channel capacity for some discrete-time systems is unachievable by linear time-invariant (LTI) encoders/decoder
Orthogonal learning particle swarm optimization
Particle swarm optimization (PSO) relies on its
learning strategy to guide its search direction. Traditionally,
each particle utilizes its historical best experience and its neighborhood’s
best experience through linear summation. Such a
learning strategy is easy to use, but is inefficient when searching
in complex problem spaces. Hence, designing learning strategies
that can utilize previous search information (experience) more
efficiently has become one of the most salient and active PSO
research topics. In this paper, we proposes an orthogonal learning
(OL) strategy for PSO to discover more useful information that
lies in the above two experiences via orthogonal experimental
design. We name this PSO as orthogonal learning particle swarm
optimization (OLPSO). The OL strategy can guide particles to
fly in better directions by constructing a much promising and
efficient exemplar. The OL strategy can be applied to PSO with
any topological structure. In this paper, it is applied to both global
and local versions of PSO, yielding the OLPSO-G and OLPSOL
algorithms, respectively. This new learning strategy and the
new algorithms are tested on a set of 16 benchmark functions, and
are compared with other PSO algorithms and some state of the
art evolutionary algorithms. The experimental results illustrate
the effectiveness and efficiency of the proposed learning strategy
and algorithms. The comparisons show that OLPSO significantly
improves the performance of PSO, offering faster global convergence,
higher solution quality, and stronger robustness
Error Function Attack of chaos synchronization based encryption schemes
Different chaos synchronization based encryption schemes are reviewed and
compared from the practical point of view. As an efficient cryptanalysis tool
for chaos encryption, a proposal based on the Error Function Attack is
presented systematically and used to evaluate system security. We define a
quantitative measure (Quality Factor) of the effective applicability of a chaos
encryption scheme, which takes into account the security, the encryption speed,
and the robustness against channel noise. A comparison is made of several
encryption schemes and it is found that a scheme based on one-way coupled
chaotic map lattices performs outstandingly well, as judged from Quality
Factor
Probing Dark Energy with the Kunlun Dark Universe Survey Telescope
Dark energy is an important science driver of many upcoming large-scale
surveys. With small, stable seeing and low thermal infrared background, Dome A,
Antarctica, offers a unique opportunity for shedding light on fundamental
questions about the universe. We show that a deep, high-resolution imaging
survey of 10,000 square degrees in \emph{ugrizyJH} bands can provide
competitive constraints on dark energy equation of state parameters using type
Ia supernovae, baryon acoustic oscillations, and weak lensing techniques. Such
a survey may be partially achieved with a coordinated effort of the Kunlun Dark
Universe Survey Telescope (KDUST) in \emph{yJH} bands over 5000--10,000 deg
and the Large Synoptic Survey Telescope in \emph{ugrizy} bands over the same
area. Moreover, the joint survey can take advantage of the high-resolution
imaging at Dome A to further tighten the constraints on dark energy and to
measure dark matter properties with strong lensing as well as galaxy--galaxy
weak lensing.Comment: 9 pages, 6 figure
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