Showing papers by "Ioannis Pitas published in 1985"
01 Apr 1985
TL;DR: Estimation theory is used to determine good estimates of the velocity and of the object image from known wavefield measurements to improve the quality of the final image.
Abstract: Waves (acoustic or electromagnetic) are used in many areas, such as ultrasonic medicine, geophysical oil prospecting, etc., for non-destructive imaging of the interior of objects, such as the earth and the human body. Wavefield measurements recorded on the surface of an object are inverted according to the wave equation to give an "image" of the interior of the object. This inversion usually enhances the noise present in the measurements and degrades the quality of the final image. Another source of degradation of the image is the insufficient knowledge of some properties of the medium, such as the wave propagation velocity. The aim of this paper is to use estimation theory to determine good estimates of the velocity and of the object image from known wavefield measurements.
1 citations
TL;DR: In this article, a method for the computation of cyclic convolutions in Galois fields that minimizes the computational complexity of the algorithm is presented. But this method is not suitable for all applications.
Abstract: The computation of cyclic convolutions in Galois fields is an integral part of coding theory and formulation as well as of many signal processing applications. In this paper, we introduce a method for the computation of such convolutions that minimizes, in theory, the computational complexity of the algorithm. We also propose special-purpose computer architecture schemes for the efficient realization of the algorithm, and in general, for efficient calculation of convolutions in Galois fields.
1 citations
TL;DR: A fixed point error analysis reveals that the realization proposed has better error characteristics than other realizations considered and is suitable to VLSI implementation.
TL;DR: These techniques can be used as an alternative in the construction of convolution algorithms when the optimal method (formulated by Winograd) is inapplicable.