Based on the characteristic of the scattering light by the underwater bubble film that the declining edge has a obvious hypo-peak region, the arithmetic of distilling the characteristic
parameters of the region is designed and applied to the experimental signals. These parameters serve as the input of the perceptron neural network and the network's output judges whether the
bubble film exists or not. The result indicates that this method has effective detecting capability against the different underwater bubble films.
To fix the strict relation between the valve pressure and bubble film's parameter the
high-speed camera is used in this paper to record the situation of underwater air bubble films in
the flume. Then the single picture is intercepted from the record to calculating the size distribution
and numeric density of bubbles through partitioning the picture into some special districts
combined with element analysis. Moreover the moving speed of bubbles could be also fixed by
drawing the track of bubbles when several consecutive intercepted pictures were compared
together. These results can provide some reference of the target character for laboratorial
underwater laser detection of wake bubbles.
The primary characteristics of light scattering by water medium and small particles are analyzed based on the
scattering theory. Compare the differences between two method to fix the deflection angle, one is Rayleigh expressions,
the other is sampling the H-G function. The light scattering intensity distribution on conditions of variety of wavelengths
and particle's semidiameters are calculated using Mie scattering expressions. The emluator of photon moving underwater
is completed, which is validated taking exponential attenuation law of beam transmitting as standard, then several set of
simulations proceed, accordingly some rules of underwater optical echo signal are concluded. In the end, the attenuation
experiment of beams in different wavelengths, and the experiment of pulse laser detecting underwater air bubble film are
conducted.
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