2,612 research outputs found
Neuro-flow Dynamics and the Learning Processes
A new description of the neural activity is introduced by the neuro-flow
dynamics and the extended Hebb rule. The remarkable characteristics of the
neuro-flow dynamics, such as the primacy and the recency effect during
awakeness or sleep, are pointed out.Comment: 8 pages ,10 Postscript figures, LaTeX file, to appear in Chaos,
Solitons and Fractal
Scaling of the magnetic entropy and magnetization in YbRh_2(Si_{0.95}Ge_{0.05})_2
The magnetic entropy of YbRh_2(Si_{0.95}Ge_{0.05})_2 is derived from
low-temperature ( mK) specific heat measurements. Upon field-tuning
the system to its antiferromagnetic quantum critical point unique temperature
over magnetic field scaling is observed indicating the disintegration of heavy
quasiparticles. The field dependence of the entropy equals the temperature
dependence of the dc-magnetization as expected from the Maxwell relation. This
proves that the quantum-critical fluctuations affect the thermal and magnetic
properties in a consistent way.Comment: 6 pages, 2 figures, manuscript submitted to SCES2004 conferenc
Coefficient of Restitution for Viscoelastic Spheres: The Effect of Delayed Recovery
The coefficient of normal restitution of colliding viscoelastic spheres is
computed as a function of the material properties and the impact velocity. From
simple arguments it becomes clear that in a collision of purely repulsively
interacting particles, the particles loose contact slightly before the distance
of the centers of the spheres reaches the sum of the radii, that is, the
particles recover their shape only after they lose contact with their collision
partner. This effect was neglected in earlier calculations which leads
erroneously to attractive forces and, thus, to an underestimation of the
coefficient of restitution. As a result we find a novel dependence of the
coefficient of restitution on the impact rate.Comment: 11 pages, 2 figure
Inferring network connectivity using kinetic Ising models
Poster presentation</p
Orientation and Alignment Echoes
We present what is probably the simplest classical system featuring the echo
phenomenon - a collection of randomly oriented free rotors with dispersed
rotational velocities. Following excitation by a pair of time-delayed impulsive
kicks, the mean orientation/alignment of the ensemble exhibits multiple echoes
and fractional echoes. We elucidate the mechanism of the echo formation by
kick-induced filamentation of phase space, and provide the first experimental
demonstration of classical alignment echoes in a thermal gas of CO_2 molecules
excited by a pair of femtosecond laser pulses
Analysis of ensemble learning using simple perceptrons based on online learning theory
Ensemble learning of nonlinear perceptrons, which determine their outputs
by sign functions, is discussed within the framework of online learning and
statistical mechanics. One purpose of statistical learning theory is to
theoretically obtain the generalization error. This paper shows that ensemble
generalization error can be calculated by using two order parameters, that is,
the similarity between a teacher and a student, and the similarity among
students. The differential equations that describe the dynamical behaviors of
these order parameters are derived in the case of general learning rules. The
concrete forms of these differential equations are derived analytically in the
cases of three well-known rules: Hebbian learning, perceptron learning and
AdaTron learning. Ensemble generalization errors of these three rules are
calculated by using the results determined by solving their differential
equations. As a result, these three rules show different characteristics in
their affinity for ensemble learning, that is ``maintaining variety among
students." Results show that AdaTron learning is superior to the other two
rules with respect to that affinity.Comment: 30 pages, 17 figure
Method of variational calculation of influence of the propulsion plants of forestry machines upon the frozen and thawing soil grounds
The forests, which grow in the conditions of complete expansion of the perpetually frozen ground, are unique forests in accordance with their taxational characteristics, quality indicators of the felled timber, and the ecological functions, which these forests perform in the nature. They are characterised by the low biological productivity, as well as by the high vulnerability due to climatological changes and human economic activities. It is fair to say that conservation of the permafrost is one of the main functions of the forests, which grow within the cryolithozone. Because of this, it is necessary to ensure special regimes for the forestry management and forest exploitation within the forests of the cryolithozone. We formulated the variational problem in order to determine influence of the changeability of the physical and mechanical properties of the thawing soil ground at the boundary with the permafrost ground. © 2019 SERSC
Effects of Diversity on Multi-agent Systems: Minority Games
We consider a version of large population games whose agents compete for
resources using strategies with adaptable preferences. The games can be used to
model economic markets, ecosystems or distributed control. Diversity of initial
preferences of strategies is introduced by randomly assigning biases to the
strategies of different agents. We find that diversity among the agents reduces
their maladaptive behavior. We find interesting scaling relations with
diversity for the variance and other parameters such as the convergence time,
the fraction of fickle agents, and the variance of wealth, illustrating their
dynamical origin. When diversity increases, the scaling dynamics is modified by
kinetic sampling and waiting effects. Analyses yield excellent agreement with
simulations.Comment: 41 pages, 16 figures; minor improvements in content, added
references; to be published in Physical Review
Optimal Resource Allocation in Random Networks with Transportation Bandwidths
We apply statistical physics to study the task of resource allocation in
random sparse networks with limited bandwidths for the transportation of
resources along the links. Useful algorithms are obtained from recursive
relations. Bottlenecks emerge when the bandwidths are small, causing an
increase in the fraction of idle links. For a given total bandwidth per node,
the efficiency of allocation increases with the network connectivity. In the
high connectivity limit, we find a phase transition at a critical bandwidth,
above which clusters of balanced nodes appear, characterised by a profile of
homogenized resource allocation similar to the Maxwell's construction.Comment: 28 pages, 11 figure
Higher-order Kerr terms allow ionization-free filamentation in gases
We show that higher-order nonlinear indices (, , , )
provide the main defocusing contribution to self-channeling of ultrashort laser
pulses in air and Argon at 800 nm, in contrast with the previously accepted
mechanism of filamentation where plasma was considered as the dominant
defocusing process. Their consideration allows to reproduce experimentally
observed intensities and plasma densities in self-guided filaments.Comment: 11 pages, 6 figures (11 panels
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