4,762 research outputs found
LEP Indications for Two Light Higgs Bosons and U(1)' Model
Reanalyses of LEP data have shown preference to two light CP-even Higgs
bosons. We discuss implications of such a Higgs boson spectrum for the minimal
supersymmetric model extended by a Standard Model singlet chiral superfield and
an additional Abelian gauge invariance (the U(1)' model). We, in particular,
determine parameter regions that lead to two light CP-even Higgs bosons while
satisfying existing bounds on the mass and mixings of the extra vector boson.
In these parameter regions, the pseudoscalar Higgs is found to be nearly
degenerate in mass with either the lightest or next-to-lightest Higgs boson.
Certain parameters of the U(1)' model such as the effective mu parameter are
found to be significantly bounded by the LEP two-light-Higgs signal.Comment: 20 pp, 7 figs, 2 table
Cooperative Localization under Limited Connectivity
We report two decentralized multi-agent cooperative localization algorithms
in which, to reduce the communication cost, inter-agent state estimate
correlations are not maintained but accounted for implicitly. In our first
algorithm, to guarantee filter consistency, we account for unknown inter-agent
correlations via an upper bound on the joint covariance matrix of the agents.
In the second method, we use an optimization framework to estimate the unknown
inter-agent cross-covariance matrix. In our algorithms, each agent localizes
itself in a global coordinate frame using a local filter driven by local dead
reckoning and occasional absolute measurement updates, and opportunistically
corrects its pose estimate whenever it can obtain relative measurements with
respect to other mobile agents. To process any relative measurement, only the
agent taken the measurement and the agent the measurement is taken from need to
communicate with each other. Consequently, our algorithms are decentralized
algorithms that do not impose restrictive network-wide connectivity condition.
Moreover, we make no assumptions about the type of agents or relative
measurements. We demonstrate our algorithms in simulation and a
robotic~experiment.Comment: 9 pages, 5 figure
On the Positive Effect of Delay on the Rate of Convergence of a Class of Linear Time-Delayed Systems
This paper is a comprehensive study of a long observed phenomenon of increase
in the stability margin and so the rate of convergence of a class of linear
systems due to time delay. We use Lambert W function to determine (a) in what
systems the delay can lead to increase in the rate of convergence, (b) the
exact range of time delay for which the rate of convergence is greater than
that of the delay free system, and (c) an estimate on the value of the delay
that leads to the maximum rate of convergence. For the special case when the
system matrix eigenvalues are all negative real numbers, we expand our results
to show that the rate of convergence in the presence of delay depends only on
the eigenvalues with minimum and maximum real parts. Moreover, we determine the
exact value of the maximum rate of convergence and the corresponding maximizing
time delay. We demonstrate our results through a numerical example on the
practical application in accelerating an agreement algorithm for
networked~systems by use of a delayed feedback
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