13,122 research outputs found
Continuous-time consensus under persistent connectivity and slow divergence of reciprocal interaction weights
In this paper, we present new results on consensus for continuous-time multi-
agent systems. We introduce the assumptions of persistent connectivity of the
interaction graph and of slow divergence of reciprocal interaction weights.
Persistent connectivity can be considered as the counterpart of the notion of
ultimate connectivity used in discrete- time consensus protocols. Slow
divergence of reciprocal interaction weights generalizes the assumption of
cut-balanced interactions. We show that under these two assumptions, the
continuous-time consensus protocol succeeds: the states of all the agents
converge asymptotically to a common value. Moreover, our proof allows us to
give an estimate of the rate of convergence towards the consensus. We also
provide two examples that make us think that both of our assumptions are tight
Synthesis for Constrained Nonlinear Systems using Hybridization and Robust Controllers on Simplices
In this paper, we propose an approach to controller synthesis for a class of
constrained nonlinear systems. It is based on the use of a hybridization, that
is a hybrid abstraction of the nonlinear dynamics. This abstraction is defined
on a triangulation of the state-space where on each simplex of the
triangulation, the nonlinear dynamics is conservatively approximated by an
affine system subject to disturbances. Except for the disturbances, this
hybridization can be seen as a piecewise affine hybrid system on simplices for
which appealing control synthesis techniques have been developed in the past
decade. We extend these techniques to handle systems subject to disturbances by
synthesizing and coordinating local robust affine controllers defined on the
simplices of the triangulation. We show that the resulting hybrid controller
can be used to control successfully the original constrained nonlinear system.
Our approach, though conservative, can be fully automated and is
computationally tractable. To show its effectiveness in practical applications,
we apply our method to control a pendulum mounted on a cart
Continuous-Time Consensus under Non-Instantaneous Reciprocity
We consider continuous-time consensus systems whose interactions satisfy a
form or reciprocity that is not instantaneous, but happens over time. We show
that these systems have certain desirable properties: They always converge
independently of the specific interactions taking place and there exist simple
conditions on the interactions for two agents to converge to the same value.
This was until now only known for systems with instantaneous reciprocity. These
result are of particular relevance when analyzing systems where interactions
are a priori unknown, being for example endogenously determined or random. We
apply our results to an instance of such systems.Comment: 12 pages, 4 figure
Nutrigenomics and immune function in fish : new insights from omics technologies
This study was funded by BBSRC grant BB/M026604/1.Peer reviewedPublisher PD
Tweezers controlled resonator
We experimentally demonstrate trapping a microdroplet with an optical tweezer
and then enabling it as a microresonator by bringing it close to a tapered
fiber coupler. Our tweezers facilitated the tuning of the coupling from the
under-coupled to the critically coupled regime with an optical Q of 12 million
and microresonator size at the 85 mirons scale.Comment: 5 pages, 4 figure
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