| Sea surface oil spill pollution usually exists on the sea surface with different weathering states,such as different thickness oil films,different distribution states,emulsified oil spill and so on.Ocean laser induced fluorescence(LIF)is one of the most effective monitoring techniques for sea surface oil spills.It has the advantages of high sensitivity,convenience and flexibility,strong real-time performance and no blind area detection.Except for the detection method of thin oil film with continuous distribution in the unemulsified stage of oil spill pollution in LIF detection technology,there are no available theoretical research results and mature detection methods for discontinuously distributed oil film,thick oil film,water-in-oil and oil-in-water in two different emulsification stages.In view of the fact that LIF detection has not yet established targeted detection theories and methods for different stages and distribution types of sea surface oil spill,it is necessary to carry out LIF oil spill area classification detection.To study the detection characteristics of different types of oil spill areas is the basis and premise of identifying and detecting different areas of surface oil spill pollution.On the basis of adding a visual camera to the LIF detection system,detection characteristics of different sea surface oil spill areas base on LIF and visual image were studied.First of all,the oil spill area of the sea surface was divided and the optical properties of all kinds of areas were studied.The complex weathering state of oil spill on the sea surface was deeply analyzed.Combined the ability and detection method of LIF to detect sea surface oil spill and the weathering state,the oil spill area was divided.The optical properties of oil spill area category,namely,inherent optical properties,fluorescence properties and Raman scattering light properties,were studied.Combined with the particle size distribution characteristics of oil droplets and water droplets in oil emulsions,the intrinsic optical properties of oil-in-water emulsion and water-in-oil emulsion were studied based on Mie scattering theory,and the effects of emulsification time and concentration on the intrinsic optical properties were analyzed.The fluorescence characteristics of oil-in-water emulsion and water-in-oil emulsion were studied by stern-volmer method,and the effects of different concentrations on the fluorescence characteristics were analyzed.Secondly,the fluorescent simulation studies of sea surface oil spill category were carried out.Based on Monte Carlo method,the fluorescence simulation model of sea surface oil spill was constructed.Based on the fluorescence simulation model and the intrinsic optical parameters of different oil spill regions,the fluorescence simulations of different oil products,different thickness oil films,different water cut oil-in-water emulsions and different concentrations of water-in-oil emulsion were carried out,and the fluorescence distribution was analyzed from different emission directions and different spatial locations.The influences of several detection parameters including excitation and emission wavelength,incident angle,fluorescence receiving area,receiving field angle and emulsification time of oil spill emulsion on the fluorescence of oil spill were analyzed.Thirdly,the fluorescence spectrum features and image features of the oil spill film region of the sea surface were analyzed and extracted.Fluorescence intensity ratio,Raman peak intensity ratio and fluorescence intensity ratio inhomogeneity were defined respectively for continuous and discontinuous oil film regions on the sea surface.The reduced oil spill thickness was used to reflect the pollution of oil spill emulsion,and the characteristics of different oil spill regions were extracted by simulation and experiment.The oil spill image was collected,and the edge detection of the oil spill image was carried out by using Susan operator.The image features of different oil spill regions were analyzed,and the color moments and color histogram features of each component of RGB and HIS color space were obtained and analyzed.Finally,thickness characteristics of different oil film areas of sea surface oil spill were studied.For thin,thick and discontinuous oil films,the corresponding thickness estimation methods were used to characterize the thickness characteristics of the corresponding regions.Raman inversion algorithm was used to characterize the thickness characteristics of thin oil film.For the thick oil film region,the determination methods of even and uneven thick oil film regions were given,and the fluorescence intensity ratio edge thickness assessment method suitable was proposed to characterize the thickness characteristics of even thick oil film region.The multi-point acquisition method was used to characterize the thickness characteristics of discontinuous oil film area.The correctness and rationality of the methods used in this paper were verified by experiments. |
