Abstract: The present invention is related to a method for identifying in a given semantic graph of linked concepts a set of concepts matching the content of a text, the semantic graph of linked concepts being stored in at least one equipment connected to a network, the methods comprising of the following steps: inputting a sample text in natural language at a workstation connected to the network; performing a semantic analysis of the sample text to extract a set of initial concepts belonging to the given semantic graph; accessing the equipment to identify a list of candidate concepts in the given semantic graph, the candidate concepts being the concepts of the semantic graph within a given maximum distance according to a given distance function away from an initial concept; calculating for each candidate concept a proximity score representative of the distances between the candidate concept and each initial concept; identifying as matching concepts the candidate concepts with the highest proximity score.

Abstract: The present invention is related to a method for identifying in a given semantic graph of linked concepts a set of concepts matching the content of a text, the semantic graph of linked concepts being stored in at least one equipment connected to a network, the methods comprising of the following steps: inputting a sample text in natural language at a workstation connected to the network; performing a semantic analysis of the sample text to extract a set of initial concepts belonging to the given semantic graph; accessing the equipment to identify a list of candidate concepts in the given semantic graph, the candidate concepts being the concepts of the semantic graph within a given maximum distance according to a given distance function away from an initial concept; calculating for each candidate concept a proximity score representative of the distances between the candidate concept and each initial concept; identifying as matching concepts the candidate concepts with the highest proximity score.

Abstract: A hybrid wavefront generator for bridging shadow zones for use with Kirchhoff migration. A graticule of travel-time grid points is mapped over a velocity model of an area of interest. The data assigned to each travel-time grid point are initialized using a unique code. By use of a conventional travel-time generator, wavefront travel times are calculated for the respective travel-time grid points. The calculated travel time, if valid, replaces the unique code previously resident therein. Wavefront travel times are re-evaluated for each travel-time grid point using a finite-difference travel-time solver. The quantity resident in each travel-time grid point is examined. If the quantity found is the unique initialization code, the unique initialization code is replaced by the re-evaluated finite-difference travel time. If a valid wavefront travel time is found, no further action takes place.

Abstract: An array of output image points is distributed over a velocity model of a subsurface region of interest. A fan of rays is shot from each of a plurality of acoustic source points along the surface, the angular separation between the rays being equal to .pi./n, where n is the number of rays. A family of traveltime wavefronts is erected at selected time intervals, .DELTA.t, along the ray trajectories. The resulting wavefront map is superimposed over the array of output image points. Sub-arrays of output image points will lie within discrete traveltime cells, the widths of which are defined by the separation between adjacent rays paths and the heights are defined by the wavefront separation distance. Ray segments, wavefront segments and output image points are identified by a velocity layer index. A velocity interface that may cut across a traveltime cell, divides the cell into two parts, each having a different layer index.