17,990 research outputs found
Optical properties of perovskite alkaline earth titanates : a formulation
In this communication we suggest a formulation of the optical conductivity as
a convolution of an energy resolved joint density of states and an
energy-frequency labelled transition rate. Our final aim is to develop a scheme
based on the augmented space recursion for random systems. In order to gain
confidence in our formulation, we apply the formulation to three alkaline earth
titanates CaTiO_3, SrTiO_3 and BaTiO_3 and compare our results with available
data on optical properties of these systems.Comment: 19 pages, 9 figures, Submitted to Journal of Physics: Condensed
Matte
Phase stability analysis in Fe-Pt and Co-Pt alloy systems: An augmented space study
We have studied the problem of phase stability in Fe-Pt and Co-Pt alloy
systems. We have used the orbital peeling technique in the conjunction of
augmented space recursion based on the tight binding linear orbital method as
the method for the calculation of pair interaction energies. In particular, we
have generalized our earlier technique to take into account of magnetic effects
for the cases where the magnetic transition is higher than the order disorder
chemical transition temperature as in the case of CoPt. Our theoretical
results obtained within this framework successfully reproduce the
experimentally observed trends.Comment: 17 pages, 9 Figures. Accepted for publication in Journal of Physics :
Condensed Matte
Interacting spinor and scalar fields in Bianchi type-I Universe filled with viscous fluid: exact and numerical solutions
We consider a self-consistent system of spinor and scalar fields within the
framework of a Bianchi type I gravitational field filled with viscous fluid in
presence of a term. Exact self-consistent solutions to the
corresponding spinor, scalar and BI gravitational field equations are obtained
in terms of , where is the volume scale of BI universe. System of
equations for and \ve, where \ve is the energy of the viscous fluid,
is deduced. Some special cases allowing exact solutions are thoroughly studied.Comment: 18 pages, 6 figure
Minimization of Handoff Failure Probability for Next-Generation Wireless Systems
During the past few years, advances in mobile communication theory have
enabled the development and deployment of different wireless technologies,
complementary to each other. Hence, their integration can realize a unified
wireless system that has the best features of the individual networks.
Next-Generation Wireless Systems (NGWS) integrate different wireless systems,
each of which is optimized for some specific services and coverage area to
provide ubiquitous communications to the mobile users. In this paper, we
propose to enhance the handoff performance of mobile IP in wireless IP networks
by reducing the false handoff probability in the NGWS handoff management
protocol. Based on the information of false handoff probability, we analyze its
effect on mobile speed and handoff signaling delay.Comment: 16 Page
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