15,578 research outputs found
Reliable routing scheme for indoor sensor networks
Indoor Wireless sensor networks require a highly dynamic, adaptive routing scheme to deal with the high rate of topology changes due to fading of indoor wireless channels. Besides that, energy consumption rate needs to be consistently distributed among sensor nodes and efficient utilization of battery power is essential. If only the link reliability metric is considered in the routing scheme, it may create long hops routes, and the high quality paths will be frequently used. This leads to shorter lifetime of such paths; thereby the entire network's lifetime will be significantly minimized. This paper briefly presents a reliable load-balanced routing (RLBR) scheme for indoor ad hoc wireless sensor networks, which integrates routing information from different layers. The proposed scheme aims to redistribute the relaying workload and the energy usage among relay sensor nodes to achieve balanced energy dissipation; thereby maximizing the functional network lifetime. RLBR scheme was tested and benchmarked against the TinyOS-2.x implementation of MintRoute on an indoor testbed comprising 20 Mica2 motes and low power listening (LPL) link layer provided by CC1000 radio. RLBR scheme consumes less energy for communications while reducing topology repair latency and achieves better connectivity and communication reliability in terms of end-to-end packets delivery performance
Speckle-visibility spectroscopy: A tool to study time-varying dynamics
We describe a multispeckle dynamic light scattering technique capable of
resolving the motion of scattering sites in cases that this motion changes
systematically with time. The method is based on the visibility of the speckle
pattern formed by the scattered light as detected by a single exposure of a
digital camera. Whereas previous multispeckle methods rely on correlations
between images, here the connection with scattering site dynamics is made more
simply in terms of the variance of intensity among the pixels of the camera for
the specified exposure duration. The essence is that the speckle pattern is
more visible, i.e. the variance of detected intensity levels is greater, when
the dynamics of the scattering site motion is slow compared to the exposure
time of the camera. The theory for analyzing the moments of the spatial
intensity distribution in terms of the electric field autocorrelation is
presented. It is demonstrated for two well-understood samples, a colloidal
suspension of Brownian particles and a coarsening foam, where the dynamics can
be treated as stationary. However, the method is particularly appropriate for
samples in which the dynamics vary with time, either slowly or rapidly, limited
only by the exposure time fidelity of the camera. Potential applications range
from soft-glassy materials, to granular avalanches, to flowmetry of living
tissue.Comment: review - theory and experimen
Radiation-induced nucleic acid synthesis in L cells under energy deprivation
Radiation induced nucleic acid synthesis in energy deprived L cell
The Dynamics of a Classical Spinning Particle in Vaidya Space-Time
Based on the Mathisson-Papapetrou-Dixon (MPD) equations and the Vaidya
metric, the motion of a spinning point particle orbiting a non-rotating star
while undergoing radiation-induced gravitational collapse is studied in detail.
A comprehensive analysis of the orbital dynamics is performed assuming distinct
central mass functions which satisfy the weak energy condition, in order to
determine a correspondence between the choice of mass function and the spinning
particle's orbital response, as reflected in the gravitational waves emitted by
the particle. The analysis presented here is likely most beneficial for the
observation of rotating solar mass black holes or neutron stars in orbit around
intermediate-sized Schwarzschild black holes undergoing radiation collapse. The
possibility of detecting the effects of realistic mass accretion based on this
approach is considered. While it seems unlikely to observe such effects based
on present technology, they may perhaps become observable with the advent of
future detectors.Comment: REVTeX file, 20 pages, 26 figure
Asymmetric Non-Abelian Orbifolds and Model Building
The rules for the free fermionic string model construction are extended to
include general non-abelian orbifold constructions that go beyond the real
fermionic approach. This generalization is also applied to the asymmetric
orbifold rules recently introduced. These non-abelian orbifold rules are quite
easy to use. Examples are given to illustrate their applications.Comment: 30 pages, Revtex 3.
Interferometric weak value deflections: quantum and classical treatments
We derive the weak value deflection given in a paper by Dixon et al. (Phys.
Rev. Lett. 102, 173601 (2009)) both quantum mechanically and classically. This
paper is meant to cover some of the mathematical details omitted in that paper
owing to space constraints
On explicit results at the intersection of the Z_2 and Z_4 orbifold subvarieties in K3 moduli space
We examine the recently found point of intersection between the Z_2 and Z_4
orbifold subvarieties in the K3 moduli space more closely. First we give an
explicit identification of the coordinates of the respective Z_2 and Z_4
orbifold theories at this point. Secondly we construct the explicit
identification of conformal field theories at this point and show the
orthogonality of the two subvarieties.Comment: Latex, 23 page
Spinning test particles and clock effect in Schwarzschild spacetime
We study the behaviour of spinning test particles in the Schwarzschild
spacetime. Using Mathisson-Papapetrou equations of motion we confine our
attention to spatially circular orbits and search for observable effects which
could eventually discriminate among the standard supplementary conditions
namely the Corinaldesi-Papapetrou, Pirani and Tulczyjew. We find that if the
world line chosen for the multipole reduction and whose unit tangent we denote
as is a circular orbit then also the generalized momentum of the
spinning test particle is tangent to a circular orbit even though and
are not parallel four-vectors. These orbits are shown to exist because the spin
induced tidal forces provide the required acceleration no matter what
supplementary condition we select. Of course, in the limit of a small spin the
particle's orbit is close of being a circular geodesic and the (small)
deviation of the angular velocities from the geodesic values can be of an
arbitrary sign, corresponding to the possible spin-up and spin-down alignment
to the z-axis. When two spinning particles orbit around a gravitating source in
opposite directions, they make one loop with respect to a given static observer
with different arrival times. This difference is termed clock effect. We find
that a nonzero gravitomagnetic clock effect appears for oppositely orbiting
both spin-up or spin-down particles even in the Schwarzschild spacetime. This
allows us to establish a formal analogy with the case of (spin-less) geodesics
on the equatorial plane of the Kerr spacetime. This result can be verified
experimentally.Comment: IOP macros, eps figures n. 2, to appear on Classical and Quantum
gravity, 200
Speckle visibility spectroscopy and variable granular fluidization
We introduce a dynamic light scattering technique capable of resolving motion
that changes systematically, and rapidly, with time. It is based on the
visibility of a speckle pattern for a given exposure duration. Applying this to
a vibrated layer of glass beads, we measure the granular temperature and its
variation with phase in the oscillation cycle. We observe several transitions
involving jammed states, where the grains are at rest during some portion of
the cycle. We also observe a two-step decay of the temperature on approach to
jamming.Comment: 4 pages, 4 figures, experimen
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