6,690 research outputs found
Cooperative Global Robust Stabilization for a Class of Nonlinear Multi-Agent Systems and its Application
This paper studies the cooperative global robust stabilization problem for a
class of nonlinear multi-agent systems. The problem is motivated from the study
of the cooperative global robust output regulation problem for the class of
nonlinear multi-agent systems in normal form with unity relative degree which
was studied recently under the conditions that the switching network is
undirected and some nonlinear functions satisfy certain growth condition. We
first solve the stabilization problem by using the multiple Lyapunov functions
approach and the average dwell time method. Then, we apply this result to the
cooperative global robust output regulation problem for the class of nonlinear
systems in normal form with unity relative degree under directed switching
network, and have removed the conditions that the switching network is
undirected and some nonlinear functions satisfy certain growth condition.Comment: 9 pages, 1 figure. This paper was submitted to the journal
"Automatica
Event-Triggered Cooperative Robust Practical Output Regulation for a Class of Linear Multi-Agent Systems
In this paper, we consider the event-triggered cooperative robust practical
output regulation problem for a class of linear minimum-phase multi-agent
systems. We first convert our problem into the cooperative robust practical
stabilization problem of a well defined augmented system Based on the
distributed internal model approach. Then, we design a distributed
event-triggered output feedback control law together with a distributed
output-based event-triggered mechanism to stabilize the augmented system, which
leads to the solvability of the cooperative robust practical output regulation
problem of the original plant. Our distributed control law can be directly
implemented in a digital platform provided that the distributed triggering
mechanism can monitor the continuous-time output information from neighboring
agents. Finally, we illustrate our design by an example.Comment: This paper has been accepted for publication in Automatica on May 21,
201
Adaptive Leader-Following Consensus for a Class of Higher-Order Nonlinear Multi-Agent Systems with Directed Switching Networks
In this paper, we study the leader-following consensus problem for a class of
uncertain nonlinear multi-agent systems under jointly connected directed
switching networks. The uncertainty includes constant unbounded parameters and
external disturbances. We first extend the recent result on the adaptive
distributed observer from global asymptotical convergence to global exponential
convergence. Then, by integrating the conventional adaptive control technique
with the adaptive distributed observer, we present our solution by a
distributed adaptive state feedback control law. Our result is illustrated by
the leader-following consensus problem for a group of van der Pol oscillators.Comment: 21 pages, 5 figures. In this replacement version, the higher-order
case is considered instead of the second-order case. Also, the main
difference of this version from the reference [16] is that Appendix B is
added to show the existence of the limit of the function V(t) defined in the
equation (33) as t tends to infinit
Cooperative Global Robust Output Regulation for a Class of Nonlinear Multi-Agent Systems by Distributed Event-Triggered Control
This paper studies the event-triggered cooperative global robust output
regulation problem for a class of nonlinear multi-agent systems via a
distributed internal model design. We show that our problem can be solved
practically in the sense that the ultimate bound of the tracking error can be
made arbitrarily small by adjusting a design parameter in the proposed
event-triggered mechanism. Our result offers a few new features. First, our
control law is robust against both external disturbances and parameter
uncertainties, which are allowed to belong to some arbitrarily large prescribed
compact sets. Second, the nonlinear functions in our system do not need to
satisfy the global Lipchitz condition. Thus our systems are general enough to
include some benchmark nonlinear systems that cannot be handled by existing
approaches. Finally, our control law is a specific distributed output-based
event-triggered control law, which lends itself to a direct digital
implementation.Comment: This paper has been submitted to a journal on July 17, 201
Exploring Lexical, Syntactic, and Semantic Features for Chinese Textual Entailment in NTCIR RITE Evaluation Tasks
We computed linguistic information at the lexical, syntactic, and semantic
levels for Recognizing Inference in Text (RITE) tasks for both traditional and
simplified Chinese in NTCIR-9 and NTCIR-10. Techniques for syntactic parsing,
named-entity recognition, and near synonym recognition were employed, and
features like counts of common words, statement lengths, negation words, and
antonyms were considered to judge the entailment relationships of two
statements, while we explored both heuristics-based functions and
machine-learning approaches. The reported systems showed robustness by
simultaneously achieving second positions in the binary-classification subtasks
for both simplified and traditional Chinese in NTCIR-10 RITE-2. We conducted
more experiments with the test data of NTCIR-9 RITE, with good results. We also
extended our work to search for better configurations of our classifiers and
investigated contributions of individual features. This extended work showed
interesting results and should encourage further discussion.Comment: 20 pages, 1 figure, 26 tables, Journal article in Soft Computing
(Spinger). Soft Computing, online. Springer, Germany, 201
Baryon number fluctuations in the 2+1 flavor low energy effective model
High order cumulants of the baryon number distribution are calculated in a
2+1 flavor low energy effective model. Quantum fluctuations are encoded through
the functional renormalization group approach. The chiral and deconfinement
phase transitions are investigated at finite temperature and baryon chemical
potential. The equation of state for the QCD matter, fluctuations of the baryon
number and the strangeness up to sixth order are calculated, and one finds the
results are consistent with those from lattice QCD.Comment: 17 pages, 13 figures, 2 tables. One figure added and one figure
updated, references added. To match the version published in PR
Quantum bit commitment with cheat sensitive binding and approximate sealing
This paper proposes a cheat sensitive quantum bit commitment (CSQBC) scheme
based on single photons, in which Alice commits a bit to Bob. Here, Bob only
can cheat the committed bit with probability close to with the increasing
of used single photons' amount. And if Alice altered her committed bit after
commitment phase, she will be detected with probability close to with the
increasing of used single photons' amount. The scheme is easy to be realized
with nowadays technology
Online dictionary learning for kernel LMS. Analysis and forward-backward splitting algorithm
Adaptive filtering algorithms operating in reproducing kernel Hilbert spaces
have demonstrated superiority over their linear counterpart for nonlinear
system identification. Unfortunately, an undesirable characteristic of these
methods is that the order of the filters grows linearly with the number of
input data. This dramatically increases the computational burden and memory
requirement. A variety of strategies based on dictionary learning have been
proposed to overcome this severe drawback. Few, if any, of these works analyze
the problem of updating the dictionary in a time-varying environment. In this
paper, we present an analytical study of the convergence behavior of the
Gaussian least-mean-square algorithm in the case where the statistics of the
dictionary elements only partially match the statistics of the input data. This
allows us to emphasize the need for updating the dictionary in an online way,
by discarding the obsolete elements and adding appropriate ones. We introduce a
kernel least-mean-square algorithm with L1-norm regularization to automatically
perform this task. The stability in the mean of this method is analyzed, and
its performance is tested with experiments
Edge-Preserving Piecewise Linear Image Smoothing Using Piecewise Constant Filters
Most image smoothing filters in the literature assume a piecewise constant
model of smoothed output images. However, the piecewise constant model
assumption can cause artifacts such as gradient reversals in applications such
as image detail enhancement, HDR tone mapping, etc. In these applications, a
piecewise linear model assumption is more preferred. In this paper, we propose
a simple yet very effective framework to smooth images of piecewise linear
model assumption using classical filters with the piecewise constant model
assumption. Our method is capable of handling with gradient reversal artifacts
caused by the piecewise constant model assumption. In addition, our method can
further help accelerated methods, which need to quantize image intensity values
into different bins, to achieve similar results that need a large number of
bins using a much smaller number of bins. This can greatly reduce the
computational cost. We apply our method to various classical filters with the
piecewise constant model assumption. Experimental results of several
applications show the effectiveness of the proposed method
Global Robust Practical Output Regulation for Nonlinear Systems in Output Feedback Form by Output-Based Event-Triggered Control
In this paper, we study the event-triggered global robust practical output
regulation problem for a class of nonlinear systems in output feedback form
with any relative degree. Our approach consists of the following three steps.
First, we design an internal model and an observer to form the so-called
extended augmented system. Second, we convert the original problem into the
event-triggered global robust practical stabilization problem of the extended
augmented system. Third, we design an output-based event-triggered control law
and a Zeno-free output-based event-triggered mechanism to solve the
stabilization problem, which in turn leads to the solvability of the original
problem. Finally, we apply our main result to the tracking problem of the
controlled hyper-chaotic Lorenz systems.Comment: This work was submitted to a journal on June 7, 201
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