Translations:Convolutional model/4/en

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The basic building block of such a model is a description of the oscillating bubble produced by an air gun. The model must be able to cope with the interactions of the bubbles produced by the array, including the problem of heat transfer between the bubble and the water. Such models are required to predict accurately the shape of the pressure wave generated by the air-gun array. It is well known that the surface reflection coefficient (for an upgoing pressure wave) of the sea-to-air interface approximates the value of -1. This nearly perfect reflection leads to a strong ghost at both the source and the receiver. At different frequencies, ghosts will interfere destructively or constructively with the primary reflection arrival. The source wavelet produced by the air-gun array, along with the ghosting effects and any other near-surface effects, result in a waveform called the signature wavelet. Because it is produced by a physical phenomenon, a signature wavelet necessarily must be causal (i.e., one-sided). However, because the bubble pulses of the air guns have large oscillations well after the time of initiation (i.e., time zero), the source signature that results from an air-gun array generally is not minimum phase.