Abstract: Embodiments of this application disclose a headword extraction method performed by a computer device. The method includes: obtaining a sentence feature of a target sentence and word features of a plurality of words in the target sentence; extracting semantics of the sentence feature of the target sentence to obtain a semantic feature of the target sentence, and extracting semantics of the word feature of each word to obtain a semantic feature of the word; obtaining a respective matching degree between the semantic feature of each of the plurality of words and the semantic feature of the target sentence; and determining, among the plurality of words in the target sentence, a word with a largest corresponding matching degree as a headword of the target sentence. The method can improve the accuracy of headwords extracted from the target sentence.

Abstract: A method includes: obtaining a first image including a target item; selecting a plurality of reference images corresponding to the first image from a database; performing word segmentation on item text information corresponding to the plurality of reference images to obtain a plurality of words; and extracting a key word meeting a reference condition from the plurality of words, and determining the extracted key word as an item name of the target item.

Abstract: The present application relates to geophysical survey, particularly provides an inversion velocity model, a method for establishing the same and a method for acquiring images of underground structure. The method for establishing inversion velocity model comprises: converting observation seismic records into first intermediary data which contains data with frequency no higher than a first predetermined frequency; calculating synthetic seismic records based on a set initial velocity model and converting the synthetic seismic records into second intermediary data which also contains data with frequency no higher than the first predetermined frequency; establishing an objective function based on the first intermediary data and the second intermediary data; calculating a velocity gradient of seismic wave based on the objective function; calculating a iteration step of the velocity gradient; determining the inversion velocity model based on the velocity gradient and the iteration step.

Abstract: The present application relates to geophysical survey, particularly provides an inversion velocity model, a method for establishing the same and a method for acquiring images of underground structure. The method for establishing inversion velocity model comprises: converting observation seismic records into first intermediary data which contains data with frequency no higher than a first predetermined frequency; calculating synthetic seismic records based on a set initial velocity model and converting the synthetic seismic records into second intermediary data which also contains data with frequency no higher than the first predetermined frequency; establishing an objective function based on the first intermediary data and the second intermediary data; calculating a velocity gradient of seismic wave based on the objective function; calculating a iteration step of the velocity gradient; determining the inversion velocity model based on the velocity gradient and the iteration step.