|
Choosing by Mapping
of Models for Propagation Losses and Interference Parameters
for Radio Networks Design
--S
R Meneses G , R Linares y M , M Cuevas and J López-Bonilla
The development of
radio networks has prompted an examination of the propagation
characteristics encountered at coverage zone. Many models
have been proposed to predict propagation losses and communication
performance, without considering interference problems. In
addition, because of variety of the available methods, the
appropriate selection of one of them for a particular situation
can be difficult. In this paper, a new technique to radio
networks design in urban and rural areas, which allows choosing
the best, by mapping of models for the propagation losses
and interference parameters is presented. Field strength and
the problems of the interference parameter estimation are
described by using the average distance conception performance
for a variety of radio communication links. A concrete mapping
of models for different kinds of zones is presented.
©
2008 IUP . All Rights Reserved.
Factorization Method
for Three Scalar Fields and
BPS Bounds
--J
Sadeghi and A Mohammadi
In this paper, a class
of systems of three coupled real scalar fields is considered
and also the general form of the stability equation is constructed.
In order to discuss the stability of system the equations
of motion with factorization method are solved. With the help
of associated Jacobi differential equation the normal mode
fluctuation is obtained .
©
2008 IUP . All Rights Reserved.
Electronic Structure
of the Interface YBa2Cu3O7/GaAs
--A
E García, J Camas, S Mendoza,R Baquero-Salaquarda,
L M García-Cruz and R Baquero
Charge redistribution
in high-Tc superconductors due to structural defects
or interfaces is known to be crucial for electronic applications
as the band structure is modified on a local scale. In order
to investigate these effects in more detail, the interface
of YBa2Cu3O7 (YBCO) with
the semiconductor GaAs is considered. It is started from ab
initio calculations for the normal state YBCO-metal and
for the GaAs semiconductor. For that purpose, the Density
Functional Theory (DFT) together with the Full-Potential Linearized
Augmented Plane Wave (FP-LAPW) method is used as it is implemented
in the Wien2k code. The GaAs interface layer is found to be
metallic, a result that is of intrinsic interest.
©
2008 IUP . All Rights Reserved.
Conductivity and
Ion Transport Characterization of a PEO Based Conducting Polymer
Electrolyte System
--K
Vijaya Kumar , G Keerthi , G Nataraju and U V Subba Rao
Solid polymer electrolyte
system, Polyethylene Oxide (PEO) complexed with potassium
bicarbonate (KHCO3) salt has been prepared by solution-cast
technique. Several experimental techniques such as IR, Differential
Scanning Calorimetry (DSC), composition dependence conductivity,
temperature dependence conductivity in the temperature range
of 308-368 K and transport number measurements have been employed
to characterize this polymer electrolyte system. The conductivity
of the (PEO+KHCO3) electrolyte is about 103
times larger than that of pure PEO at room temperature.
The transference data has shown that the charge transport
in these polymer electrolyte systems is predominantly due
to ions.
©
2008 IUP . All Rights Reserved.
The Photon and
its Mass
--Baiju
George and P Appala Naidu
Gauge theory, the
fundamental theory of interaction and the special theory of
relativity, with its firm roots in Maxwell's electrodynamics,
were the two main constituents of the die in which photon
was moulded. So it naturally produced a zero mass photon.
Advent of general theory of relativity greatly reduced the
domain of validity of special theory. But it did not challenge
the assigned characters of photon. Momentum, an inherent property
of photon caused to think in the direction of massive photon,
a theoretically and conceptually viable alternative. Proca
electrodynamics is the most successful frame work for this
alternative concept. Based on this frame work, the finite
range theory has been analyzed for the nature of potential,
field and dispersion of electromagnetic radiations at terrestrial
and extra terrestrial levels to set an upper limit for rest
mass of photon. The upper limit set by various experimental
methods so far not reached up to the limit set by the principle
of uncertainty. But the present limit is not too far from
this ultimate limit. In a similar manner efforts are in progress
to set an upper limit to photon charge. Stability of photon
is also a matter of concern.
©
2008 IUP . All Rights Reserved.
|
