10,760 research outputs found
Dynamics of Charged Bulk Viscous Collapsing Cylindrical Source With Heat Flux
In this paper, we have explored the effects of dissipation on the dynamics of
charged bulk viscous collapsing cylindrical source which allows the out follow
of heat flux in the form of radiations. Misner-Sharp formulism has been
implemented to drive the dynamical equation in term of proper time and radial
derivatives. We have investigated the effects of charge and bulk viscosity on
the dynamics of collapsing cylinder. To determine the effects of radial heat
flux, we have formulated the heat transport equations in the context of
Mller-Israel-Stewart theory by assuming that thermodynamics
viscous/heat coupling coefficients can be neglected within some approximations.
In our discussion, we have introduced the viscosity by the standard
(non-casual) thermodynamics approach. The dynamical equations have been coupled
with the heat transport equation equation, the consequences of resulting
coupled heat equation have been analyzed in detail.Comment: 17 Pages, no figur
Higher Dimensional Inhomogeneous Perfect Fluid Collapse in \emph{f(R)} Gravity
This paper is about the -dimensional gravitational contraction of
inhomogeneous fluid without heat flux in the framework of metric theory
of gravity. Matching conditions for two regions of a star has been derived by
using the Darmois junction conditions. For the analytic solution of equations
of motion in modified theory of gravity, we have taken scalar curvature
as constant. Hence final result of gravitational collapse in this frame work is
the existence of black hole and cosmological horizons, both of these form
earlier than singularity. It has been shown that constant curvature term
( is constant scalar curvature) slows down the collapsing
process.Comment: 17 Pages, to appear in European Physical Journal
Evaluating the Success of Malaysia’s Exchange Controls (1998-99)
The paper evaluates in depth, the exchange control measures imposed by Malaysia in September-1998. Controls are evaluated using three alternative benchmarks—Malaysia vs. itself (pre-controls), vs. ex-ante forecasts of Malaysia for the year-1999, and Malaysia vs. the other affected East Asian economies. The comparisons suggest that controls were effective in turning some key variables around, especially the stock market index, and also enabled Malaysia to incur fewer social costs vis-à -vis the other crisis-economies. Finally, a GARCH measure of Malaysia’s interest-rate and stock-market volatility is obtained and the impact of controls on volatility studied. Evidence was found of volatility responding differentially to the Russian crisis (before controls) and the Brazilian crisis (after controls), indicating that controls helped insulate Malaysia from developments in global financial markets. Overall the paper confirms the necessity of LDCs retaining the capital controls option in the absence of material efforts to reform the international financial architecture and the inadequacy of conventional policy tools to effectively deal with present-day capital flows.
Effects of Electromagnetic Field on Gravitational Collapse
In this paper, the effect of electromagnetic field has been investigated on
the spherically symmetric collapse with the perfect fluid in the presence of
positive cosmological constant. Junction conditions between the static exterior
and non-static interior spherically symmetric spacetimes are discussed. We
study the apparent horizons and their physical significance. It is found that
electromagnetic field reduces the bound of cosmological constant by reducing
the pressure and hence collapsing process is faster as compared to the perfect
fluid case. This work gives the generalization of the perfect fluid case to the
charged perfect fluid. Results for the perfect fluid case are recovered.Comment: 17 pages, accepted for publication in Mod. Phys. Lett
M-ATTEMPT: A New Energy-Efficient Routing Protocol for Wireless Body Area Sensor Networks
In this paper, we propose a new routing protocol for heterogeneous Wireless
Body Area Sensor Networks (WBASNs); Mobility-supporting Adaptive
Threshold-based Thermal-aware Energy-efficientMulti-hop ProTocol (M-ATTEMPT). A
prototype is defined for employing heterogeneous sensors on human body. Direct
communication is used for real-time traffic (critical data) or on-demand data
while Multi-hop communication is used for normal data delivery. One of the
prime challenges in WBASNs is sensing of the heat generated by the implanted
sensor nodes. The proposed routing algorithm is thermal-aware which senses the
link Hot-spot and routes the data away from these links. Continuous mobility of
human body causes disconnection between previous established links. So,
mobility support and energy-management is introduced to overcome the problem.
Linear Programming (LP) model for maximum information extraction and minimum
energy consumption is presented in this study. MATLAB simulations of proposed
routing algorithm are performed for lifetime and successful packet delivery in
comparison with Multi-hop communication. The results show that the proposed
routing algorithm has less energy consumption and more reliable as compared to
Multi-hop communication.Comment: arXiv admin note: substantial text overlap with arXiv:1208.609
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