3,369 research outputs found
Determination of RF source power in WPSN using modulated backscattering
A wireless sensor network (WSN) is a wireless network consisting of spatially
distributed autonomous devices using sensors to cooperatively monitor physical
or environmental conditions, such as temperature, sound, vibration, pressure,
motion or pollutants, at different locations. During RF transmission energy
consumed by critically energy-constrained sensor nodes in a WSN is related to
the life time system, but the life time of the system is inversely proportional
to the energy consumed by sensor nodes. In that regard, modulated
backscattering (MB) is a promising design choice, in which sensor nodes send
their data just by switching their antenna impedance and reflecting the
incident signal coming from an RF source. Hence wireless passive sensor
networks (WPSN) designed to operate using MB do not have the lifetime
constraints. In this we are going to investigate the system analytically. To
obtain interference-free communication connectivity with the WPSN nodes number
of RF sources is determined and analyzed in terms of output power and the
transmission frequency of RF sources, network size, RF source and WPSN node
characteristics. The results of this paper reveal that communication coverage
and RF Source Power can be practically maintained in WPSN through careful
selection of design parametersComment: 10 pages; International Journal on Soft Computing (IJSC) Vol.3, No.1
(2012). arXiv admin note: text overlap with arXiv:1001.5339 by other author
Conformally Invariant Path Integral Formulation of the Wess-Zumino-Witten Liouville Reduction
The path integral description of the Wess-Zumino-Witten Liouville
reduction is formulated in a manner that exhibits the conformal invariance
explicitly at each stage of the reduction process. The description requires a
conformally invariant generalization of the phase space path integral methods
of Batalin, Fradkin, and Vilkovisky for systems with first class constraints.
The conformal anomaly is incorporated in a natural way and a generalization of
the Fradkin-Vilkovisky theorem regarding gauge independence is proved. This
generalised formalism should apply to all conformally invariant reductions in
all dimensions. A previous problem concerning the gauge dependence of the
centre of the Virasoro algebra of the reduced theory is solved.Comment: Plain TeX file; 28 Page
Duality in Liouville Theory as a Reduced Symmetry
The origin of the rather mysterious duality symmetry found in quantum
Liouville theory is investigated by considering the Liouville theory as the
reduction of a WZW-like theory in which the form of the potential for the
Cartan field is not fixed a priori. It is shown that in the classical theory
conformal invariance places no condition on the form of the potential, but the
conformal invariance of the classical reduction requires that it be an
exponential. In contrast, the quantum theory requires that, even before
reduction, the potential be a sum of two exponentials. The duality of these two
exponentials is the fore-runner of the Liouville duality. An interpretation for
the reflection symmetry found in quantum Liouville theory is also obtained
along similar lines.Comment: Plain TeX file; 9 page
Path Integral Formulation of the Conformal Wess-Zumino-Witten to Liouville Reduction
The quantum Wess-Zumino-Witten Liouville reduction is formulated using
the phase space path integral method of Batalin, Fradkin, and Vilkovisky,
adapted to theories on compact two dimensional manifolds. The importance of the
zero modes of the Lagrange multipliers in producing the Liouville potential and
the WZW anomaly, and in proving gauge invariance, is emphasised. A previous
problem concerning the gauge dependence of the Virasoro centre is solved.Comment: Plain TeX file, 15 page
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