William J. Fitzgerald

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Bright and dark flashes are typical artifacts in degraded motion picture material. The distortion is referred to as "dirt and sparkle" in the motion picture industry. This is caused either by dirt becoming attached to the frames of the film, or by the film material being abraded. The visual result is random patches of the frames having grey level values(More)
—We propose some Bayesian methods to address the problem of fitting a signal modeled by a sequence of piecewise constant linear (in the parameters) regression models, for example, autoregressive or Volterra models. A joint prior distribution is set up over the number of the changepoints/knots, their positions, and over the orders of the linear regression(More)
The core/periphery structure is ubiquitous in network studies. The discrete version of the concept is that individuals in a group belong to either the core, which has a high density of ties, or to the periphery, which has a low density of ties. The density of ties between the core and the periphery may be either high or low. If the core/periphery structure(More)
This paper presents a number of model based interpolation schemes tailored to the problem of interpolating missing regions in image sequences. These missing regions may be of arbitrary size and of random, but known, location. This problem occurs regularly with archived film material. The film is abraded or obscured in patches, giving rise to bright and dark(More)
—In this paper, an efficient particle filtering algorithm is developed to solve the problem of demodulation of-ary modulated signals under conditions of fading channels in the presence of non-Gaussian additive noise. Simulations for MDPSK signals are presented. The results show that the algorithm outperforms the current methods.
In this paper, application of particle filtering techniques to different classes of problems arising in digital communications is considered. Several approaches are reviewed, and a brief simulation study for demodulation in fading conditions and joint symbol/channel coefficients/code delay estimation for DS spread-spectrum systems is carried out.
We develop a new receiver for joint symbol, channel characteristics, and code delay estimation for DS spread spectrum systems under conditions of multipath fading. The approach is based on particle filtering techniques and combines sequential importance sampling, a selection scheme, and a variance reduction technique. Several algorithms involving both(More)