4,148 research outputs found
Local null controllability of the N-dimensional Navier-Stokes system with N-1 scalar controls in an arbitrary control domain
In this paper we deal with the local null controllability of the
N-dimensional Navier-Stokes system with internal controls having one vanishing
component. The novelty of this work is that no condition is imposed on the
control domain
Competition, efficiency and collective behavior in the "El Farol" bar model
The El Farol bar model, proposed to study the dynamics of competition of
agents in a variety of contexts (W. B. Arthur, Amer. Econ. Assoc. Pap. and
Proc. 84, 406 (1994)) is studied. We characterize in detail the three regions
of the phase diagram (efficient, inefficient and better than random) of the
simplest version of the model (D. Challet and Y.-C. Zhang, Physica A, 246, 407
(1997)). The efficient region is shown to have a rich structure, which is
investigated in some detail. Changes in the payoff function enhance further the
tendency of the model towards a wasteful distribution of resources.Comment: 7 pages Latex, 7 Postscript figures; changed reference,
acknowledgments included. Accepted for publication in Europen Physics Journal
Barter, Bearer, and Bitcoin: The Likely Future of Stateless Virtual Money
Over the past few years, virtual money has emerged via the Internet. Although currently unregulated, Internal Revenue System Notice 2014-21 will most likely cause virtual money to lose its mass appeal in the United States. Historically, other means of tax avoidance, including barter transactions and bearer bonds, have suffered the same fate. Virtual money will likely have more success as a technology than as a means of value
MOJAVE: Monitoring of Jets in AGN with VLBA Experiments. IV. The Parent Luminosity Function of Radio-Loud Blazars
(Abridged) We use a complete sample of active galactic nuclei (AGN) selected
on the basis of relativistically beamed 15 GHz radio flux density to derive the
parent radio luminosity function (RLF) of bright radio-selected blazar cores.
We use a maximum likelihood method to fit a beamed RLF to the observed data and
thereby recover the parameters of the intrinsic (unbeamed) RLF. We analyze two
subsamples of the MOJAVE sample: the first contains only objects of known FR II
class, with a total of 103 sources, and the second subsample adds 24 objects of
uncertain FR class for a total of 127 sources. Both subsamples exclude four
known FR I radio galaxies and two gigahertz-peaked spectrum sources. We obtain
good fits to both subsamples using a single power law intrinsic RLF with pure
density evolution function. We find that a previously reported break in the
observed MOJAVE RLF actually arises from using incomplete bins (because of the
luminosity cutoff) across a steep and strongly evolving RLF, and does not
reflect a break in the intrinsic RLF. The derived space density of the parent
population of the FR II sources from the MOJAVE sample (with L>1.3e25 W/Hz) is
approximately 1600/Gpc^3.Comment: 31 pages, 7 figures and 2 tables. Accepted for publication in ApJ.
Changes: classification of sources based on radio morphology instead of
optical classes; added the parameters of the RLF of the FR II sources; added
more explanations; added a table listing the sample sources; added 2 extra
figures related to the observed break in the RLF; updated reference
Barter, Bearer, and Bitcoin: The Likely Future of Stateless Virtual Money
Over the past few years, virtual money has emerged via the Internet. Although currently unregulated, Internal Revenue System Notice 2014-21 will most likely cause virtual money to lose its mass appeal in the United States. Historically, other means of tax avoidance, including barter transactions and bearer bonds, have suffered the same fate. Virtual money will likely have more success as a technology than as a means of value
Influence of external information in the minority game
The influence of a fixed number of agents with the same fixed behavior on the
dynamics of the minority game is studied. Alternatively, the system studied can
be considered the minority game with a change in the comfort threshold away
from half filling. Agents in the frustrated, non ergodic phase tend to
overreact to the information provided by the fixed agents, leading not only to
large fluctuations, but to deviations of the average occupancies from their
optimal values. Agents which discount their impact on the market, or which use
individual strategies reach equilibrium states, which, unlike in the absence of
the external information provided by the fixed agents, do not give the highest
payoff to the collective.Comment: 8 pages, 6 figure
Exact controllability to the trajectories for parabolic PDEs with nonlocal nonlinearities
This paper deals with the analysis of the internal control of a parabolic PDE with nonlinear diffusion, nonlocal in space. In our main result, we prove the local exact controllability to the trajectories with distributed controls, locally supported in space. The main ingredients of the proof are a compactness-uniqueness argument and Kakutani’s Fixed-Point Theorem in a suitable functional setting. Some possible extensions and open problems concerning other nonlocal systems are presented.Ministerio de EconomÃa y Competitividad (MINECO). Españ
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