16,967 research outputs found
Robust identification from band-limited data
Consider the problem of identifying a scalar bounded-input/bounded-output stable transfer function from pointwise measurements at frequencies within a bandwidth. We propose an algorithm which consists of building a sequence of maps from data to models converging uniformly to the transfer function on the bandwidth when the number of measurements goes to infinity, the noise level to zero, and asymptotically meeting some gauge constraint outside. Error bounds are derived, and the procedure is illustrated by numerical experiment
Patch-recovery filters for curvature in discontinuous Galerkin-based level-set methods
In two-phase flow simulations, a difficult issue is usually the treatment of
surface tension effects. These cause a pressure jump that is proportional to
the curvature of the interface separating the two fluids. Since the evaluation
of the curvature incorporates second derivatives, it is prone to numerical
instabilities. Within this work, the interface is described by a level-set
method based on a discontinuous Galerkin discretization. In order to stabilize
the evaluation of the curvature, a patch-recovery operation is employed. There
are numerous ways in which this filtering operation can be applied in the whole
process of curvature computation. Therefore, an extensive numerical study is
performed to identify optimal settings for the patch-recovery operations with
respect to computational cost and accuracy.Comment: 25 pages, 8 figures, submitted to Communications in Computational
Physic
Rational-operator-based depth-from-defocus approach to scene reconstruction
This paper presents a rational-operator-based approach to depth from defocus (DfD) for the reconstruction of three-dimensional scenes from two-dimensional images, which enables fast DfD computation that is independent of scene textures. Two variants of the approach, one using the Gaussian rational operators (ROs) that are based on the Gaussian point spread function (PSF) and the second based on the generalized Gaussian PSF, are considered. A novel DfD correction method is also presented to further improve the performance of the approach. Experimental results are considered for real scenes and show that both approaches outperform existing RO-based methods
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