Alt-Azimuth Ephemeries

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Extending common-azimuth migration

We present a review of common-azimuth prestack depth migration theory and propose a new extension to the original method. In common-azimuth migration theory, source and receiver raypaths are constrained to lie on the same plane at each depth level. By using data with a broader range of cross-line offsets, we increase the number of raypaths examined and consider more information. Consequently, o...

Multi-azimuth velocity estimation

It is well known that the inverse problem of estimating interval velocities from reflection data is poorly constrained in 2-D. We show that the interval velocity estimation problem in 3-D is much better constrained when the velocity function is estimated by jointly inverting the data collected along multiple offset-azimuth, even when the azimuth range is fairly limited. We extend to 3-D the lin...

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ALT: Another Likelihood Tool

Although there are many phylogenetic reconstruc-tion tools available [1][4], their purpose is in generalto solve specific problems or to apply a limited num-ber of evolution models.We present a new program, ALT — AnotherLikelihood Tool, which implements Felsenstein’smaximum likelihood algorithm [2][3] two importantcharacteristics: it is written in a highly modular<lb...