2,020 research outputs found
On Distributed Power Control for Uncoordinated Dual Energy Harvesting Links: Performance Bounds and Near-Optimal Policies
In this paper, we consider a point-to-point link between an energy harvesting
transmitter and receiver, where neither node has the information about the
battery state or energy availability at the other node. We consider a model
where data is successfully delivered only in slots where both nodes are active.
Energy loss occurs whenever one node turns on while the other node is in sleep
mode. In each slot, based on their own energy availability, the transmitter and
receiver need to independently decide whether or not to turn on, with the aim
of maximizing the long-term time-average throughput. We present an upper bound
on the throughput achievable by analyzing a genie-aided system that has
noncausal knowledge of the energy arrivals at both the nodes. Next, we propose
an online policy requiring an occasional one-bit feedback whose throughput is
within one bit of the upper bound, asymptotically in the battery size. In order
to further reduce the feedback required, we propose a time-dilated version of
the online policy. As the time dilation gets large, this policy does not
require any feedback and achieves the upper bound asymptotically in the battery
size. Inspired by this, we also propose a near-optimal fully uncoordinated
policy. We use Monte Carlo simulations to validate our theoretical results and
illustrate the performance of the proposed policies.Comment: 8 page
Dielectric properties of Li2O-3B2O3 glasses
The frequency and temperature dependence of the dielectric constant and the
electrical conductivity of the transparent glasses in the composition
Li2O-3B2O3 (LBO) were investigated in the 100 Hz- 10 MHz frequency range. The
dielectric constant and the loss in the low frequency regime were electrode
material dependent. Dielectric and electrical relaxations were respectively
analyzed using the Cole-Cole and electric modulus formalisms. The dielectric
relaxation mechanism was discussed in the framework of electrode and charge
carrier (hopping of the ions) related polarization using generalized Cole-Cole
expression. The frequency dependent electrical conductivity was rationalized
using Jonscher's power law. The activation energy associated with the dc
conductivity was 0.80 \pm 0.02 eV, which was ascribed to the motion of Li+ ions
in the glass matrix. The activation energy associated with dielectric
relaxation was almost equal to that of the dc conductivity, indicating that the
same species took part in both the processes. Temperature dependent behavior of
the frequency exponent (n) suggested that the correlated barrier hopping model
was the most apposite to rationalize the electrical transport phenomenon in
Li2O-3B2O3 glasses. These glasses on heating at 933 K/10h resulted in the known
non-linear optical phase LiB3O5.Comment: 32 pages, 13 figure
The glass transition and crystallization kinetic studies on BaNaB9O15 glasses
Transparent glasses of BaNaB9O15 (BNBO) were fabricated via the conventional
melt-quenching technique. The amorphous and the glassy nature of the
as-quenched samples were respectively, confirmed by X-ray powder diffraction
(XRD) and differential scanning calorimetry (DSC). The glass transition and
crystallization parameters were evaluated under non-isothermal conditions using
DSC. The correlation between the heating rate dependent glass transition and
the crystallization temperatures was discussed and deduced the Kauzmann
temperature for BNBO glass-plates and powdered samples. The values of the
Kauzmann temperature for the plates and powdered samples were 776 K and 768 K,
respectively. Approximation-free method was used to evaluate the
crystallization kinetic parameters for the BNBO glass samples. The effect of
the sample thickness on the crystallization kinetics of BNBO glasses was also
investigated.Comment: 23 pages, 12 figure
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