297,019 research outputs found
An Efficient Approach for Computing Optimal Low-Rank Regularized Inverse Matrices
Standard regularization methods that are used to compute solutions to
ill-posed inverse problems require knowledge of the forward model. In many
real-life applications, the forward model is not known, but training data is
readily available. In this paper, we develop a new framework that uses training
data, as a substitute for knowledge of the forward model, to compute an optimal
low-rank regularized inverse matrix directly, allowing for very fast
computation of a regularized solution. We consider a statistical framework
based on Bayes and empirical Bayes risk minimization to analyze theoretical
properties of the problem. We propose an efficient rank update approach for
computing an optimal low-rank regularized inverse matrix for various error
measures. Numerical experiments demonstrate the benefits and potential
applications of our approach to problems in signal and image processing.Comment: 24 pages, 11 figure
Concept of spinsonde for multi-cycle measurement of vertical wind profile of tropical cyclones
Tropical cyclones and cyclogenesis are active areas of research.
Chute-operated dropsondes jointly developed by NASA and NCAR are capable of
acquiring high resolution vertical wind profile of tropical cyclones. This
paper proposes a chute-free vertical retardation technique (termed as
spinsonde) that can accurately measure vertical wind profile. Unlike the
expendable dropsondes, the spinsonde allows multi-cycle measurement to be
performed within a single flight. Proof of principle is demonstrated using a
simulation software and results indicate that the GPS ground speed correlates
with the wind speeds to within +/-5 km/h. This technique reduces flying weight
and increases payload capacity by eliminating bulky chutes. Maximum cruising
speed (Vh) achieved by the spinsonde UAV is 372 km/h.Comment: arXiv admin note: substantial text overlap with arXiv:1407.845
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