Research On Ultrasonic Method For Localization Of Pressure Gas Microporous Leakage Source

Leakage of pressurized gas will cause incalculable loss to people's lives and property safety,so it is of great significance to locate the source of microporous leakage.However,the existing positioning methods based on Direction of Arrival(DOA)and Time Delay of Arrival(TDOA)respectively have defects like false alarming,grid mismatching,and accuracy decreasing in the environment of coherent source and noise interference.In response to these problems,based on the existing research results,this paper conducts the following research work on sparse representation DOA estimation methods and TDOA methods,including:(1)Propose a sparse reconstruction DOA estimation method without grid division.In order to overcome the noise interference,an improved Pulse Coupled Neural Network(PCNN)combined with Ensemble Empirical Mode Decomposition(EEMD)is used to preprocess the collected signal to eliminate the noise interference and obtain the noise matrix at the same time.In order to overcome the interference of coherent source signals,the Toeplitz matrix reconstruction method is used to restore the rank of the covariance matrix.In order to avoid grid mismatch,the signal model is gradually decomposed around the constraint criterion of minimizing the total change,so as to gradually transform the global optimization problem into the individual wave arrival angle optimization problem with the trace minimization.In order to verify the effectiveness of the proposed method,a comparative experiment was conducted with the existing DOA estimation method.The proposed method can distinguish power spectrum peaks more easily,achieve higher estimation accuracy in an environment with low signal-to-noise ratio and interference from coherent sources and resolve power of multiple adjacent targets.(2)Propose an improved quantum genetic positioning method based on the inversion satellite model.In order to reduce the dependence of the positioning effect on the number of sensor array elements,referring to the principle of satellite four-element positioning,a set of nonlinear overdetermined equations is deduced based on the inversion relationship between the sensors and the leak source "one sending and four receiving".In order to solve the equations,the Quantum Genetic Algorithm(QGA)is introduced.In order to solve the defect that the algorithm falls into the local optimal solution,the fmincon constraint condition is added to improve it,and to search the space optimal value.In order to obtain a more accurate time delay,the internal activity items of the PCNN model is added to the denominator of the weight function for improvement,and the delay between each element is obtained and substituted into the equation solution.In order to verify that the proposed method is effective,it is compared with different calculation methods.The proposed method has better convergence performance,calculation stability,more stability and accurate positioning results in a low signal-to-noise ratio environment when only 4 sensor array elements are used.