734 research outputs found
Sigma Point Belief Propagation
The sigma point (SP) filter, also known as unscented Kalman filter, is an
attractive alternative to the extended Kalman filter and the particle filter.
Here, we extend the SP filter to nonsequential Bayesian inference corresponding
to loopy factor graphs. We propose sigma point belief propagation (SPBP) as a
low-complexity approximation of the belief propagation (BP) message passing
scheme. SPBP achieves approximate marginalizations of posterior distributions
corresponding to (generally) loopy factor graphs. It is well suited for
decentralized inference because of its low communication requirements. For a
decentralized, dynamic sensor localization problem, we demonstrate that SPBP
can outperform nonparametric (particle-based) BP while requiring significantly
less computations and communications.Comment: 5 pages, 1 figur
Close-circuit domain quadruplets in BaTiO nanorods embedded in SrTiO film
Cylindrical BaTiO3 nanorods embedded in (100)-oriented SrTiO3 epitaxial film
in a brush-like configuration are investigated in the framework of the
Ginzburg-Landau-Devonshire model. It is shown that strain compatibility at
BaTiO3/SrTiO3 interfaces keeps BaTiO3 nanorods in the rhombohedral phase even
at room temperature. Depolarization field at the BaTiO3/SrTiO3 interfaces is
reduced by an emission of the 109-degree or 71-degree domain boundaries. In
case of nanorods of about 10-80 nm diameter, the ferroelectric domains are
found to form a quadruplet with a robust flux-closure arrangement of the
in-plane components of the spontaneous polarization. The out-of-plane
components of the polarization are either balanced or oriented up or down along
the nanorod axis. Switching of the out-of-plane polarization with coercive
field of about V/m occurs as a collapse of a 71-degree cylindrical
domain boundary formed at the curved circumference surface of the nanorod. The
remnant domain quadruplet configuration is chiral, with the macroscopic
symmetry. More complex stable domain configurations with coexisting clockwise
and anticlockwise quadruplets contain interesting arrangement of strongly
curved 71-degree boundaries.Comment: Erratta - corrected error in Fig.
Simultaneous Distributed Sensor Self-Localization and Target Tracking Using Belief Propagation and Likelihood Consensus
We introduce the framework of cooperative simultaneous localization and
tracking (CoSLAT), which provides a consistent combination of cooperative
self-localization (CSL) and distributed target tracking (DTT) in sensor
networks without a fusion center. CoSLAT extends simultaneous localization and
tracking (SLAT) in that it uses also intersensor measurements. Starting from a
factor graph formulation of the CoSLAT problem, we develop a particle-based,
distributed message passing algorithm for CoSLAT that combines nonparametric
belief propagation with the likelihood consensus scheme. The proposed CoSLAT
algorithm improves on state-of-the-art CSL and DTT algorithms by exchanging
probabilistic information between CSL and DTT. Simulation results demonstrate
substantial improvements in both self-localization and tracking performance.Comment: 10 pages, 5 figure
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