A transversely isotropic (TI) model in which the tilt is constrained to be normal to the dip (DTI model) allows for simplifications in the imaging and velocity model building efforts as compared to a general TI (TTI) model. Although this model cannot be represented physically in all situations, for example, in the case of conflicting dips, it handles arbitrary reflector orientations under the a...

The problem of optimal economic operation of hydrothermal electric power systems is solved using powerful continuation method. While in conventional approach, fixed generation voltages are used to avoid convergence problems, in the proposed algorithm, they are treated as variables so that better solutions can be obtained. The algorithm is tested for a typical 5-bus and 17-bus New Zealand networ...

Twelve consecutive cases are reviewed of unilateral hypotropia due to various causes. In most of them the presenting complaint was of ipsilateral blepharoptosis. Some patients had undergone previous ineffective surgery. The surgical techniques employed and the results obtained are discussed, with emphasis on the necessity to test for inferior rectus restriction. Some interesting sensory results...

We study a data-driven approach to multi-mode interval velocity analysis in laterally inhomogeneous and anisotropic media. We obtain a simple model-independent description of long-spread reflection moveout versus offset for both symmetric and asymmetric wave modes. It resolves a trade-off between anisotropy and lateral heterogeneity. This is done using offset-dependent arrivalangle and wavefron...

We present a simple method for computing angle-domain Common Image Gathers (CIGs) using prestack reverse time migration. The proposed method is an extension of the method proposed by Rickett and Sava (2001) to compute CIGs by downward-continuation shot-profile migration. We demonstrate with a synthetic example the use of the CIG gathers for migration velocity updating. A challenge for imaging b...

Prestack depth migration of shot profiles by downward continuation is a practical imaging algorithm that is especially cost-effective for sparse-shot wide-azimuth geometries. The interpretation of offset as the displacement between the downward-propagating (shot) wavefield and upward-propagating (receiver) wavefield enables us to extract offset-domain common imagepoint (CIP) gathers during shot...