7,619 research outputs found
Distributed L1-state-and-fault estimation for Multi-agent systems
In this paper, we propose a distributed state-and-fault estimation scheme for
multi-agent systems. The proposed estimator is based on an -norm
optimization problem, which is inspired by sparse signal recovery in the field
of compressive sampling. Two theoretical results are given to analyze the
correctness of the proposed approach. First, we provide a necessary and
sufficient condition such that state and fault signals are correctly estimated.
The result presents a fundamental limitation of the algorithm, which shows how
many faulty nodes are allowed to ensure a correct estimation. Second, we
provide a sufficient condition for the estimation error of fault signals when
numerical errors of solving the optimization problem are present. An
illustrative example is given to validate the effectiveness of the proposed
approach
Superconductivity and Magnetism in REFeAsO1-xFx (RE=Rare Earth Elements)
Fluoride-doped iron-based oxypnictides containing rare-earth gadolinium
(GdFeAsO0.8F0.2) and co-doping with yttrium (Gd0.8Y0.2FeAsO0.8F0.2) have been
prepared via conventional solid state reaction at ambient pressure. The
non-yttrium substituted oxypnictide show superconducting transition as high as
43.9 K from temperature dependent resistance measurements with the Meissner
effect observed at a lower temperature of 40.8 K from temperature dependent
magnetization measurements. By replacing a small amount of gadolinium with
yttrium Tc was observed to be lowered by 10 K which might be caused by a change
in the electronic or magnetic structures since the crystal structure was not
altered.Comment: 4 pages, 4 figures, Journal of Physics: Conference Series
(Proceedings in the LT25 Low Temperature Physics Conference) Submitte
Forecasting U.S. Trade in Services
This paper provides a set of forecasts of United States international trade in services, both at the aggregate level and for four subcategories. These sectors are: travel, which is mostly tourist expenditures; passenger fares, which is mostly passenger air transportation; transportation, other than passenger transportation; and other private services, including education, financial services, insurance, telecommunications, and business, professional and technical services. A forecasting model is constructed and estimated, based on conventional economic forces of supply and demand, dependent on cost variables and income variables as well as relative prices. For forecasting purposes, these variables are taken from the Michigan Quarterly Econometric Model of the U.S. Economy, a macroeconomic forecasting model with forecasts provided regularly by the University of Michigan Research Seminar in Quantitative Economics. The equations of the services trade model are reported and discussed, and the performance of the estimated equations is evaluated. The quarterly forecast paths are provided for both aggregate and sectoral services trade, including exports and imports, through the end of 2001. Results indicate that imports will continue to rise over the forecast period, while exports, after remaining nearly stationary for several quarters in some sectors in 1999, will resume their rise thereafter. This forecasting work is to be continued, and it is suggested, in addition, that future research would be useful to explore the determinants of the production and sales of foreign services affiliates of U.S. parent companies.Services, International Trade
Associated production of a neutral top-Higgs with a heavy-quark pair in the \gamma\gamma collisions at ILC
We have studied the associated production processes of a neutral top-Higgs in
the topcolor assisted technicolor model with a pair of heavy quarks in
\gamma\gamma collisions at the International Linear Collider (ILC). We find
that the cross section for t\bar{t}h_t in \gamma\gamma collisions is at the
level of a few fb with the c.m. energy \sqrt{s}=1000 GeV, which is consistent
with the results of the cross section of t\bar{t}H in the standard model and
the cross section of t\bar{t}h in the minimal supersymmetric standard modeland
the little Higgs models. It should be distinct that hundreds of to thousands of
h_t per year can be produced at the ILC, this process of \gamma\gamma \to
t\bar{t}h_t is really interesting in testing the standard model and searching
the signs of technicolor.Comment: 4 pages, 4 figures, some references are adde
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