267 research outputs found
STRATEGY MANAGEMENT IN A MULTI-AGENT SYSTEM USING NEURAL NETWORKS FOR INDUCTIVE AND EXPERIENCE-BASED LEARNING
Intelligent agents and multi-agent systems prove to be a promising paradigm for solving problems in a distributed, cooperative way. Neural networks are a classical solution for ensuring the learning ability of agents. In this paper, we analyse a multi-agent system where agents use different training algorithms and different topologies for their neural networks, which they use to solve classification and regression problems provided by a user. Out of the three training algorithms under investigation, Backpropagation, Quickprop and Rprop, the first demonstrates inferior performance to the other two when considered in isolation. However, by optimizing the strategy of accepting or rejecting tasks, Backpropagation agents succeed in outperforming the other types of agents in terms of the total utility gained. This strategy is learned also with a neural network, by processing the results of past experiences. Therefore, we show a way in which agents can use neural network models for both external purposes and internal ones.agents, learning, neural networks, strategy management multi-agent system.
Importance of grain boundary Josephson junctions in the electron-doped infinite-layer cuprate superconductor SrLaCuO
Grain boundary bicrystal Josephson junctions of the electron-doped
infinite-layer superconductor SrLaCuO () were grown
by pulsed laser deposition. BaTiO-buffered 24\,^\circ [001]-tilt
symmetric SrTiO bicrystals were used as substrates. We examined both Cooper
pair (CP) and quasiparticle (QP) tunneling by electric transport measurements
at temperatures down to 4.2\,K. CP tunneling revealed an extraordinary high
critical current density for electron-doped cuprates of A/cm
at 4.2\,K. Thermally activated phase slippage was observed as dissipative
mechanism close to the transition temperature. Out-of-plane magnetic fields
revealed a remarkably regular Fraunhofer-like pattern as well as Fiske
and flux flow resonances, both yielding a Swihart velocity of
m/s. Furthermore, we examined the superconducting gap by means
of QP tunneling spectroscopy. The gap was found to be V-shaped with an
extrapolated zero temperature energy gap meV. No zero
bias conductance peak was observed.Comment: 6 pages, 3 figure
Superconducting thin films of MgB2 on (001)-Si by pulsed laser deposition
Superconducting thin films have been prepared on Si-substrates, using pulsed
laser deposition from a target composed of a mixture of Mg and MgB2 powders.
The films were deposited at room temperature and post-annealed at 600 degrees
C. The zero resistance transition temperatures were 12 K, with an onset
transition temperature of 27 K. Special care has been taken to avoid oxidation
of Mg in the laser plasma and deposited film, by optimizing the background
pressure of Ar gas in the deposition chamber. For this the optical emission in
the visible range from the plasma has been used as indicator. Preventing Mg
from oxidation was found to be essential to obtain superconducting films
Properties of the electron-doped infinite-layer superconductor SrLaCuO epitaxially grown by pulsed laser deposition
Thin films of the electron-doped infinite-layer cuprate superconductor
SrLaCuO (SLCO) with doping were grown by means
of pulsed laser deposition. (001)-oriented KTaO and SrTiO single
crystals were used as substrates. In case of SrTiO, a BaTiO thin film
was deposited prior to SLCO, acting as buffer layer providing tensile strain to
the SLCO film. To induce superconductivity, the as-grown films were annealed
under reducing conditions, which will be described in detail. The films were
characterized by reflection high-energy electron diffraction, atomic force
microscopy, x-ray diffraction, Rutherford backscattering spectroscopy, and
electric transport measurements at temperatures down to K. We
discuss in detail the influence of different process parameters on the final
film properties.Comment: 16 pages, 14 figure
Computer simulation of leadership, consensus decision making and collective behaviour in humans
The aim of this study is to evaluate the reliability of a
crowd simulation model developed by the authors by reproducing Dyer et al.’s experiments(published in Philosophical Transactions in 2009) on human leadership and
consensus decision-making in a computer-based environment.
The theoretical crowd model of the simulation environment is presented, and its results are compared and analysed against Dyer et al.’s original experiments.
It is concluded that the results are 11 largely consistent
with the experiments, which demonstrates the reliability of
the crowd model. Furthermore, the simulation data also reveals several additional new findings, namely:
1) the phenomena of sacrificing accuracy to reach a quicker
consensus decision found in ants colonies was also discovered in the simulation;
2) the ability of reaching consensus in groups has a direct
impact on the time and accuracy of arriving at the target
position;
3) the positions of the informed individuals or leaders
in the crowd could have significant impact on the overall
crowd movement;
4) the simulation also confirmed Dyer et al.’s anecdotal
evidence of the proportion of the leadership in large crowds
and its effect on crowd movement.
The potential applications of these findings are highlighted in the final discussion of this paper
Targets for high repetition rate laser facilities: Needs, challenges and perspectives
A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10Ã\u82 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: Dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities
Superconducting thin films of MgB2 on Si by pulsed laser deposition
Superconducting thin films have been prepared on Si-substrates, using pulsed laser deposition from a target composed of a mixture of Mg and MgB2 powders. The films were deposited at room temperature and annealed at 600°C. The zero resistance transition temperatures were 11-15.5 K, with an onset transition temperature of 27 K. Special care has been taken to avoid oxidation of Mg in the laser plasma and deposited film, by optimizing the background pressure of Ar gas in the deposition chamber. For this the optical emission in the visible range from the plasma has been used as indicator. Preventing Mg from oxidation was found to be essential to obtain superconducting films
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