693 research outputs found
Kolmogorov Dispersion for Turbulence in Porous Media: A Conjecture
We will utilise the self-avoiding walk (SAW) mapping of the vortex line
conformations in turbulence to get the Kolmogorov scale dependence of energy
dispersion from SAW statistics, and the knowledge of the disordered fractal
geometries on the SAW statistics. These will give us the Kolmogorov energy
dispersion exponent value for turbulence in porous media in terms of the size
exponent for polymers in the same. We argue that the exponent value will be
somewhat less than 5/3 for turbulence in porous media.Comment: 3 page
Universal Scaling Property of System Approaching Equilibrium
In this Letter we show that the diffusion kinetics of kinetic energy among
the atoms in non- equilibrium crystalline systems follows universal scaling
relation and obey Levy-walk properties. This scaling relation is found to be
valid for systems no matter how far they are driven out of equilibrium.Comment: 6 pages, 4 figure
Energy Management in a Cooperative Energy Harvesting Wireless Sensor Network
In this paper, we consider the problem of finding an optimal energy
management policy for a network of sensor nodes capable of harvesting their own
energy and sharing it with other nodes in the network. We formulate this
problem in the discounted cost Markov decision process framework and obtain
good energy-sharing policies using the Deep Deterministic Policy Gradient
(DDPG) algorithm. Earlier works have attempted to obtain the optimal energy
allocation policy for a single sensor and for multiple sensors arranged on a
mote with a single centralized energy buffer. Our algorithms, on the other
hand, provide optimal policies for a distributed network of sensors
individually harvesting energy and capable of sharing energy amongst
themselves. Through simulations, we illustrate that the policies obtained by
our DDPG algorithm using this enhanced network model outperform algorithms that
do not share energy or use a centralized energy buffer in the distributed
multi-nodal case.Comment: 11 pages, 4 figure
Persistent time intervals between features in solar flare hard X-ray emission
Several solar hard X-ray events (greater than 100 keV) were observed simultaneously with identical instruments on the Venera 11, 12, 13, 14, and Prognoz spacecraft. High time resolution (= 2 ms) data were stored in memory when a trigger occurred. The observations of modulation are presented with a period of 1.6 s for the event on December 3, 1978. Evidence is also presented for fast time fluctuations from an event on November 6, 1979, observed from Venera 12 and another on September 6, 1981, observed from the Solar Maximum Mission. Power spectrum analysis, epoch folding, and Monte Carlo simulation were used to evaluate the statistical significance of persistent time delays between features. The results are discussed in light of the MHD model proposed by Zaitsev and Stepanov
Crustal Oscillations of Slowly Rotating Relativistic Stars
We study low-amplitude crustal oscillations of slowly rotating relativistic
stars consisting of a central fluid core and an outer thin solid crust. We
estimate the effect of rotation on the torsional toroidal modes and on the
interfacial and shear spheroidal modes. The results compared against the
Newtonian ones for wide range of neutron star models and equations of state.Comment: 15 page
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