Research On Target Detection Technology Under Buried Mines

In our country, offshore area and port si given priority to sand bottom, after a period oftime, bottom mine will be buried by sediments. the performances of the buried mine fuze willbe poor,and the energy of the fuze wil be reduced, which lead to the method of regionalcontrol no longer valid. In such a background, the paper studied sound propagaton attenuationcharacteristics of the sediment, established sound attenuation model of different sedimentsand depths, evaluated the performance of the buried mines, proposed the ke y technologies ofthe anti burid mines, which sovled the regional control problem caused by buried and reducedthe advese effect on the buried mines, improved the target detection ability of buried mines.The thesis research results and innovations are as follows:1. An improved Biot-Stoll sound attenuation model parameters estimation method isproposed, which solved the problem of deviation estimation caused by Kozeny-carmanequation. At the same time of simplified model parameter calculation, permeability and porescale estimation emprirical formula is optimized, whch reduced the permeability and pore sizeestimation deviation. The improved model paramers estimation method can more accuratelypredict sediment sound propagation attenuation characteristics of buried mines.2. Models of different sediments and different depths of the buried mines are establishedfor single layer bottom, the sound transmission loss and spread loss is definition and deduced,and the attenuation of buried mines in corse sand, silt and silty sand are predicted. Formulti-layer bottom, models of buried mines are established either. Finally the model isverified by experiment on the lake.3. Evaluation method of buried mine fuzes is proposed, whch use the attenuation model,assessed the ship spectrum structure characteristic, target through feature, band energy anddetection performance. Theoretical analysis and simulation results show that the attenuationof low frequency energy is low, the frequency of high frequency energy is high. In order toreduce the adverse effects on the fuze, the fuze working band should be reduced.4. Based on attenuation energky of different depths and different sediments, the paperproposed a method of calculating the energy of mine fuze working band. Predict the energyloss of10Hz~5kHz band, under the buried depths of1m and2m. Theoretical analysis andsimulation show that under the same depths, coarse sand has the most impact on fuze, silt hasthe least impact on fuze, and with the increase of porosity and with the decrease of average particle diameter, buried impact on acoustic fuze has a tendency to decrease gradually.5. Put forword the anti buried bottom mine passive acoustic fuze scheme. By theapplication of the vector hydrophone, the working frequency band is reduced and the adveseeffect on the propertied of fuze is reduced too. In order to solve the problem of regionalcontrol, two key technologies is proposed which are target estimation based on vectorhydrophone and target azimuth correction based on attitude Angle sensor. Getting the attitudeinformation through of attitude Angle sensor, and by the method of rear signal processing,achieved the farget transformation between mine platform coordinae system and earthcoordiate system, which solved the problem of regional control problem and avoid themisoperation caused by buried.