| Marine oil spill accidents,such as collision of ships or oil tankers in transit,oil spill from sunken ships and oil and gas pipeline leakage,do great harm to Marine environment and sea traffic safety.After an oil spill accident occurs,detecting the distribution of the oil spill area on the sea surface is conducive to the treatment of oil spill recovery and ablation,and can greatly reduce the harm of oil spill accident.Marine navigation radar has the advantages of strong antijamming ability and 24 hours continuous monitoring,and its monitoring ability of sea oil spill and other targets has attracted more and more scholars’ attention.It is of great theoretical and practical significance to carry out oil spill monitoring research based on Marine navigation radar.In this thesis,the relevant problems of Marine navigation radar monitoring of sea oil spill,such as sea clutter inversion,same frequency interference,noise processing and other issues are studied,and the sea clutter information inversion model of sea oil spill identification effect is compared and analyzed.The main contents are as follows:(1)The formation mechanism of sea clutter and sea clutter model are analyzed.Three models of sea clutter attribute are briefly introduced: the normalized radar cross-sectional area model,the sea clutter amplitude statistical model and the sea clutter power spectrum model.The characteristics of classical models are introduced respectively,and their advantages and disadvantages and application range are analyzed.(2)According to the definition and calculation formula of backscatter cross-sectional area of sea clutter,the basic principle of Marine navigation radar detecting oil spill targets is introduced.Combining the relationship between time sequence signal and image,two mathematical models based on sea clutter inversion are proposed: sea clutter inverse model with negative exponential and sea clutter polynomial.Based on sea clutter inversion in Marine navigation radar image,the purpose of sea clutter suppression is realized,so as to realize oil spill information recognition.(3)An oil spill identification method based on sea clutter information inversion is proposed.Firstly,the original Marine navigation radar image is preprocessed,and coordinate transformation,same frequency interference suppression and speckle noise suppression are carried out to obtain the radar image after noise reduction.Secondly,the difference between the reconstructed sea clutter radar image and the preprocessed radar image is calculated to obtain the abnormal dark area in the Marine navigation radar image.Finally,the oil spill information in the image is identified and extracted by the method of threshold segmentation algorithm and connected region analysis.(4)Based on the radar image data of Dalian "July 16" oil spill accident,the feasibility and effectiveness of the oil spill information extraction method of Marine navigation radar image based on sea clutter inversion model is verified.Meanwhile,the oil spill information identification effect of two sea clutter inversion models in Marine navigation radar image is compared.It shows that the sea clutter inversion model of negative exponential model is more advantageous in oil spill identification and extraction. |
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