Study On Source Identification And Acoustic Metamaterial Lens Source Location Based On Phase Conjugation Method

With the rapid development of modernization,environmental pollution has also arisen.As a kind of environmental pollution,noise pollution is becoming more and more serious and has a serious impact on people's daily life.At present,noise control is mainly controlled by three sources: noise source,propagation path and receiver.Noise source control noise is the most effective control method,and the key to this is how to accurately identify the location noise source.Only when the position of the noise source is accurately located can the noise source be effectively controlled.The phase conjugate method as a noise source identification method can effectively identify the noise source and plays an important role in noise pollution control.In the process of sound source identification,far-field sound source recognition often fails to btain a good recognition effect.The reason is that far-field sound source recognition cannot collect the evanescent wave component of sound waves.In order to improve the resolution of far-field sound source recognition,the research and application of iterative phase conjugate method is carried out by introducing "sound" in the focus point.Acoustic hyper-lens far-field imaging is carried out by using the perfect imaging properties of acoustic hyper-lens.Research and application of positioning.In addition,in the practical application of engineering,the acoustic environment of sound source identification is usually complicated,and the sound source identification method under free field conditions is often not applicable.In order to improve the applicability of the phase conjugate method,the phase conjugate method combined with the image method is used to study the sound source identification and localization in complex environments.The main research contents of this thesis include:(1)With the aim of improving the resolution of sound source recognition,the sound source identification research based on iterative phase conjugate method and the far field sound source localization based on acoustic hyper lens are studied respectively:When the phase conjugate method is used to focus the sound source,the sound field will continue to diverge after focusing,resulting in low resolution of the sound source recognition.By introducing the concept of "sound sink",the time reversal calculation of the sound field after focusing is superimposed on the original phase conjugate sound field at the focus point.The effectiveness of the iterative phase conjugate method is verified by numerical simulation and experiment.The acoustic superlens can perform lossless propagation or even amplification propagation on the evanescent component of the acoustic wave to achieve perfect imaging of the sound source.In this thesis,a superlens with a refractive index of-1 is designed.Based on this,mul-ti-lens design is carried out to achieve perfect imaging of far-field sound sources.The phase conjugate method is combined with the acoustic hyper-lens sound source for positioning to achieve a breakthrough in sound source recognition resolution.(2)To improve the practical application ability of the project,the research on sound source identification and location under non-free field conditions is carried out.In engineering applications,the identification of sound sources requires not only the direct sound of the sound source,but also the one and multiple reflections of the boundary.In order to accurately locate the position of the noise source,phase conjugate method and image method are combined to realize sound source localization in complex environment.The phase conjugate method combined with the image method can effectively simulate multiple reflections of the boundary and eliminate the influence of interface reflection on the sound source localization.The effectiveness of the method is verified by numerical simulation.