29 results about "Nonlinear acoustics" patented technology

The invention provides a method for detecting dissolved gas in transformer oil, and belongs to the technical field of dissolved gas in transformer oil, and the method comprises the following steps: firstly, transmitting a plurality of groups of ultrasonic waves with different frequencies into the transformer oil at the same time, obtaining and preprocessing a joint spectrum, and then utilizing a wavelet multi-scale decomposition technology considering a time sliding window to obtain a pre-processed joint spectrum; the signal is disassembled into a stable spectrum and three levels of fluctuation spectrums. Extracting the characteristics of interference, spectrum attenuation, waveform complexity, coupling, energy distribution and the like from each level of fluctuation spectrum, and calculating the influence characteristics of microbubbles on ultrasonic waves, including acoustic attenuation, propagation velocity, scattering, acoustic impedance change and nonlinear acoustic characteristics. By performing weight fusion on the three-level fluctuation spectrum energy ratio, comprehensive characteristics are generated and input into a gas calculation model, so that the state of gas in transformer oil is accurately evaluated and diagnosed, and the technical problem that an existing offline sampling analysis method is difficult to meet the requirement of a power system for evaluating the running state of a transformer in real time is solved.

The invention discloses a wind turbine blade internal damage diagnosis method based on a sound field graph neural network, and belongs to the technical field of wind turbine blade state detection, and the method comprises the steps: deploying a microphone array in a cabin, and collecting an acoustic signal when a blade rotates; constructing a space sound field graph structure by taking the microphone as a node and the sound wave propagation path as an edge; extracting nonlinear acoustic features by using a physical constraint graph neural network PC-GNN; generating a damage embedding vector based on self-supervised training contrast learning; and outputting a damage probability thermodynamic diagram and positioning information. According to the method, a directional microphone array is deployed in a cabin, and a sound wave propagation space diagram structure is constructed; designing a physical constraint graph neural network PC-GNN, and embedding an acoustic wave equation as a regularization item; the problem of scarcity of damaged samples is solved by adopting self-supervised contrast learning; and finally outputting a positioning thermodynamic diagram of the internal damage of the blade.

The invention discloses an acoustic black hole vibration reduction structure, and relates to the technical field of vibration reduction and noise reduction, the acoustic black hole vibration reduction structure comprises an acoustic black hole beam, a supporting part and a damping layer, the thickness of the longitudinal section of the acoustic black hole beam is gradually increased in a power function mode in the length direction of the acoustic black hole beam, and the damping layer is arranged on the acoustic black hole beam; one end face, in the thickness direction, of the acoustic black hole beam is a plane end, one end of the supporting part makes contact with the plane end, and the contact end face, making contact with the acoustic black hole beam, of the supporting part is arc-shaped. The effective length of the acoustic black hole beam is changed through contact between the arc shape of the supporting part and the acoustic black hole beam, then the inherent frequency of the acoustic black hole beam is changed, widening of the working frequency band is achieved, the nonlinear acoustic black hole vibration reduction structure with the variable rigidity is provided, the certain working frequency band is achieved, and the vibration reduction effect is improved.

The invention discloses a method for predicting the residual fatigue life of a titanium alloy component based on frequency mixing nonlinear ultrasound. The method comprises the following steps: firstly, building a detection system; the detection system is controlled to generate low-frequency f1 and high-frequency f2 sinusoidal signals to carry out frequency mixing excitation on the titanium alloy component, and ultrasonic response signals are collected; performing frequency domain analysis on the ultrasonic response signal, extracting a characteristic amplitude and calculating a nonlinear modulation parameter beta m; then, a Nazarov-Sutin equation and an Elber equation are combined, and a theoretical prediction model of the nonlinear modulation parameter beta m changing along with the fatigue life percentage f is constructed; finally, actual measurement parameters are substituted into the model to reversely derive the consumed fatigue cycle number N, and the residual fatigue life Nr is predicted by combining the critical failure total cycle number Nt of the component. According to the method, the quantitative mapping relation between the nonlinear acoustic parameters and fatigue damage accumulation is revealed by establishing the physical model, and accurate quantitative prediction of the residual fatigue life of the titanium alloy component is achieved.

A method of non-linear acoustic non-destructive testing of a testpiece (3) comprising (i) determining a resonance frequency of a testpiece (3) by applying at least one excitation vibration to the testpiece (3) and analysing a vibrational response of the testpiece (3) to the at least one excitation vibration, (ii) applying at least one excitation vibration to the testpiece (3) at the determined resonance frequency and / or over a range of frequencies that includes the determined resonance frequency, and (iii) determining if the testpiece (3) has one or more flaws by analysing a vibrational response of the testpiece, to the at least one excitation vibration in step (ii), for non-linear behaviour. An apparatus (1) for non-linear acoustic non-destructive testing of a testpiece (3) according to the method.

The invention discloses a nonlinear acoustic transducer control method and system based on an Aubry-Mather set, and belongs to the technical field of acoustic transducers. The method comprises the following steps: firstly, based on an Aubry-Mather set theory, constructing a nonlinear vibration model used for describing nonlinear vibration of a transducer diaphragm; secondly, based on a nonlinear vibration model, regional piezoelectric driving and dynamic phase regulation are carried out to simulate a quasi-periodic fluctuation mode; then, on the basis of fluctuation characteristics disclosed by the nonlinear vibration model, a multi-diaphragm collaborative vibration system is constructed, and quasi-periodic superposition of sound waves is realized by optimizing diaphragm space layout; and finally, based on stiffness parameters in the nonlinear vibration model, integrating a micro electro mechanical system (MEMS) process and a nonlinear material, and realizing equivalent nonlinear stiffness on a physical device through gradient polarization design. The dynamic adaptability, the energy transfer efficiency and the high-frequency output performance of the transducer in a broadband range are effectively improved, and the transducer is particularly suitable for ultrasonic imaging and other high-frequency acoustic application scenes.

The invention belongs to the technical field of nonlinear acoustics, and particularly relates to an array amplitude-phase consistency calibration method of a parametric array, a program, equipment and a storage medium. According to the invention, by measuring the amplitude phase response of the high-frequency sound wave emitted by each array element, the amplitude phase response of the difference frequency sound wave is determined and compensated, so that the array amplitude phase consistency calibration of the parametric array in multiple test scenes such as a pool and an anechoic chamber can be realized. The method has high robustness for installation errors, and the calibrated array elements have more consistent difference frequency amplitude-phase response. The method is simple in implementation mode, can be suitable for various test scenes, provides necessary pre-calibration for beam forming of the parametric array, and has high application value.

The invention discloses an ultrasonic temperature measurement method and system based on multi-feature fusion, and belongs to the technical field of medical ultrasonic monitoring. The system comprises a signal acquisition module, a data processing module and an output module. The method comprises the following steps: acquiring an original radio frequency signal acquired by a monitoring probe spatially associated with a focused ultrasound treatment probe; extracting three temperature rise characteristics based on thermal strain, nonlinear sound attenuation and a Nakagami distribution statistics principle in parallel; inputting the multi-parameter characteristics into a pre-trained knowledge distillation physical information neural network model, and directly outputting a predicted temperature value; and the accumulated equivalent heat dose can be calculated according to the predicted temperature to carry out damage judgment. Through multi-parameter complementary fusion and a lightweight intelligent model, accurate and real-time non-intrusive monitoring of the temperature change of a high-temperature treatment interval greater than 50 DEG C is realized, the temperature measurement root mean square error is less than or equal to 0.8 DEG C, the single-frame processing time is less than or equal to 5ms, meanwhile, standardized thermal damage assessment is provided, and the controllability and safety of focused ultrasonic treatment are improved.

The invention relates to the technical field of nondestructive testing, and discloses a defect positioning method, device and system, electronic equipment and a medium, and the method comprises the following steps: receiving an ultrasonic signal in real time through a first ultrasonic transducer; when the ultrasonic signals are non-linear effect echoes, Fourier transform analysis is carried out on the non-linear effect echoes, a third-order non-linear coefficient is determined, and the position of a resonance center where the non-linear effect echoes are generated on the tested piece is recorded; and comparing the sizes of the three-order nonlinear coefficients corresponding to the resonance center positions, determining a target resonance center position, and positioning the target resonance center position as a defect. The defect of the tested piece is positioned by capturing the nonlinear acoustic response (nonlinear effect echo) generated when the ultrasonic wave interacts with the material defect, and the nonlinear acoustic response is not influenced by the size of the defect, so that the defect positioning precision is improved.

Embodiments relate to devices, systems, and methods for creating highly localized, remote audible zones or noise control zones by utilizing nonlinear interactions of ultrasonic beams. Ultrasonic sources may produce inaudible, straight or curved trajectories that can bypass obstacles, such as human heads or barriers or follow direct paths in open space. When intersecting at a designated target zone, the nonlinear acoustic interaction generates an audible difference-frequency wave within the human audible range, delivering targeted sound content without disturbing surrounding areas. Alternatively, the ultrasonic sources may produce beams to control and / or cancel audible content in a designated zone. These approaches enable precise, scalable, and obstacle-agnostic spatial audio and noise control with broad bandwidth, compact size, and high robustness even in reverberant environments, expanding possibilities in private communication, immersive audio, sound masking, and environmental noise mitigation.

The application discloses a strain sensor deformation real-time monitoring method and system embedded in a loudspeaker diaphragm, and relates to the technical field of intelligent control of electroacoustic transducers; a micrometer flexible sensor network is conformally sprayed on the surface of the diaphragm to collect a micro-strain sequence of the diaphragm in real time without destroying zero acoustic parameters; a one-dimensional sequence is reconstructed into a continuous three-dimensional micro-deformation topology by using an orthogonal basis matrix, and a spatial nonlinear acoustic error is extracted in combination with a rigid body reference model to perform Volterra active acoustic compensation; the fatigue degree of the diaphragm is calculated in real time based on rain flow counting and cumulative damage theory, a frequency band compression limit is automatically triggered when the fatigue is critical, and the fatigue degree is used as a safety constraint factor to dynamically limit the step length of acoustic compensation; the application breaks the offline limitation of traditional laser vibration measurement, effectively offsets the acoustic distortion caused by segmented vibration, constructs a dynamic restraint closed loop of sound quality compensation and mechanical anti-tearing, and realizes the balance between high-fidelity driving of the loudspeaker and the limit physical life.

The invention discloses a rear axle gear wear diagnosis method and system, and relates to the technical field of mechanical fault diagnosis, and the method comprises the steps: analyzing the matching relation between the wear degree and the working condition when a gear is fractured, and building a wear and fracture working condition matching model; a piezoelectric sensing network is installed outside a rear axle shell corresponding to a rear axle gear, guided waves in an ultrasonic frequency band are transmitted to the rear axle shell, ultrasonic guided wave response signals are received, nonlinear acoustic parameters are calculated, and the abrasion degree of the rear axle gear is evaluated; and performing wear degree matching analysis according to the wear fracture condition matching model, and outputting a predicted fracture matching condition for reminding. The technical problems that an existing rear axle gear abrasion diagnosis method depends on regular disassembly and inspection or an internal sensor, early warning is difficult to achieve, and the method is not suitable for mass production of vehicles are solved, the piezoelectric sensing network is installed outside the rear axle shell, non-intrusive real-time monitoring and early abrasion early warning are achieved, and the service life of the rear axle gear is prolonged. And the monitoring feasibility and adaptability are improved.

This invention discloses a modeling and optimization method for an ultrasonic enhancement device. It analyzes the device's acoustic field signal, designs a three-dimensional geometric configuration including a concave energy-concentrating structure, a metamaterial microstructure, and an acoustic lens structure, sets corresponding material and geometric parameters for each structure, evaluates the performance of the current configuration through nonlinear acoustic field simulation, and accurately simulates the simulation results of the heterogeneous interface. Then, it inputs the main field and adjoint field dual-channel solutions to obtain the sensitivity information of the design variables. Furthermore, it constructs a deep neural network model, using the geometric parameters of the metamaterial microstructure as input and the equivalent acoustic response as output, to achieve real-time performance prediction and dynamic impedance matching optimization. Combined with objective function evaluation and constraint projection mechanisms, a simulation optimization feedback loop is formed, iteratively outputting the optimal manufacturable configuration. The device designed in this invention has advantages such as being passive, low-cost, and highly adaptable, and is suitable for complex industrial applications such as partial discharge monitoring of power equipment and fault diagnosis in rail transit.

The present application relates to the technical field of intelligent sensor, specifically to a stainless steel pipe quality evaluation method and system based on detection response, comprising: constructing and emitting a specific phase encoding excitation flow, and collecting the response after the propagation in the stainless steel pipe; generating the response spectrum available for analysis by processing the response signal; determining two key physical performance parameters representing the material by analyzing the response spectrum: the bulk nonlinear acoustic characteristic value reflecting the microscopic physical properties, and the interface modulation acoustic characteristic value reflecting the structural integrity; finally, based on the comprehensive evaluation of the two determined physical performance parameters, the precise differentiation of the material physical property degradation and the internal structure discontinuity is realized. The present application can realize the synchronous analysis and evaluation of multiple physical performances of the material through one nondestructive testing.

The application discloses a choir balance guidance method and system based on voiceprint recognition, relates to the technical field of digital audio signal processing, and comprises the following steps: extracting acoustic energy features and ontology voiceprint matching features of a current time window of multiple pickup channels, and calculating time sequence change rates of both relative to historical time windows; performing orthogonal state deviation judgment based on the time sequence change rates, and locking a target pickup channel interfered by a howling sound; determining a howling sound emission source channel and an absolute propagation time delay by cross-correlation ranging within a preset time delay constraint range; inversely calculating a physical propagation distance according to the time delay, and constructing a spatial spectrum dissipation filter in combination with a nonlinear acoustic dissipation model; performing phase shift and frequency response deformation constraint on a frequency domain signal of the howling sound source by using the time delay and the filter, and generating a physically deformed howling sound prediction signal; performing targeted cancellation on the frequency domain signal of the target channel and the prediction signal, reconstructing a pure acoustic energy parameter, and generating a balance guidance instruction; and the application can solve the balance guidance distortion problem caused by howling sound aliasing.

The application discloses an intelligent ultrasonic bone knife system based on multi-modal cooperation, which comprises a low-frequency cutting module, a high-frequency pulse early warning module, a motion sensing unit, a nonlinear identification module and a coupling control module. The high-frequency pulse early warning module adopts no less than two micro piezoelectric elements, which are embedded in the blind hole in the end of the amplitude transformer knife head. The directional near-field detection towards the advancing direction of the knife head is realized through the emission phase delay or the reception phase difference. The system emits 1-3 MHz pulses during the intermittent period of low-frequency cutting, and combines the motion vector, the boundary of the soft tissue in front and the nonlinear acoustic fingerprint result to dynamically adjust the detection gap, the identification threshold and the low-frequency output power, so that the power is reduced or the output is cut off before the knife head contacts the non-bone soft tissue.

A method for generating low-frequency limited acoustic beams in a well, the method comprising: determining a transducer aperture according to a downhole borehole size, calculating a nonlinear action region of a radiated acoustic field based on the transducer aperture and a distance parameter; selecting a sound source design modulation theory model according to the nonlinear action region, determining sound source parameters of the transducer based on the sound source design modulation theory model and the transducer aperture; carrying out nonlinear radiated acoustic field simulation according to the sound source parameters, determining a critical propagation distance corresponding to a maximum value of a difference frequency sound source level, and extracting nonlinear acoustic wave signal characteristics at the distance, generating a loadable modulation signal based on the characteristics; measuring and comparing signal characteristics of the transducer under a loadable modulation signal loading state and under a natural radiated modulation signal loading state, and determining the loadable modulation signal with a larger difference frequency sound source level. The present application can generate nonlinear acoustic wave signals containing larger low-frequency components at a smaller radiated distance, and the difference frequency conversion efficiency of the generated nonlinear radiated signals is high.

The invention discloses an ultrasonic enhancement device modeling and optimizing method, which comprises the following steps of: analyzing a sound field signal of equipment, designing a three-dimensional geometrical configuration of the device, including a concave surface energy gathering structure, a metamaterial microstructure and an acoustic lens structure, setting corresponding material parameters and geometrical parameters of each structure, and evaluating the performance of the current configuration through nonlinear sound field simulation. The method comprises the following steps of: constructing a metamaterial microstructure, accurately simulating a simulation result of a heterogeneous interface, then inputting two channels of a main field and an adjoint field to solve and obtain sensitivity information of a design variable, and by constructing a deep neural network model, taking a metamaterial microstructure geometric parameter as input and taking equivalent acoustic response as output, realizing real-time performance prediction and dynamic impedance matching optimization. And a simulation optimization feedback closed loop is formed by combining objective function evaluation and a constraint projection mechanism, and an optimal manufacturable configuration is iteratively output. The device designed by the invention has the advantages of being passive, low in cost, high in adaptability and the like, and is suitable for complex industrial application scenes such as power equipment partial discharge monitoring, rail transit fault diagnosis and the like.

The invention belongs to the technical field of nonlinear acoustics and active noise control, and particularly relates to an underwater active noise control method, program and equipment adopting a virtual sensing and parameter emission technology, and a storage medium. According to the method, the auxiliary filter absorbs the information of the optimal error in the training stage to form the virtual error estimator, in the noise control process of the target noise source, an error hydrophone does not need to be arranged, signals collected by the auxiliary hydrophone are constructed into virtual error signals through the trained auxiliary filter, and the target noise source is subjected to noise control through the virtual error signals. And updating the auxiliary filter by taking the virtual error signal as a cost function, and adjusting a transmitting signal of the transmitting transducer according to the output of the updated auxiliary filter. According to the method, errors are estimated in real time through virtual sensing and closed-loop control is conducted, meanwhile, the parametric array serves as a secondary sound source, interference to the surrounding environment is reduced by means of the efficient effect of the high directivity of the parametric array in a target area, and meanwhile the low-frequency applicability is improved.

The present application relates to a method and device for calculating the effective elastic wave amplitude range of a nonlinear acoustic metamaterial, which includes: obtaining the unit cell structure of the nonlinear acoustic metamaterial, performing a force analysis on the unit cell structure to obtain the motion relationship of the unit cell structure; determining the bandgap characteristics of the nonlinear acoustic metamaterial based on the motion relationship and the perturbation method; determining the effective elastic wave amplitude range of the nonlinear acoustic metamaterial according to the bandgap characteristics of the nonlinear acoustic metamaterial, so as to re-determine the bandgap characteristics of the nonlinear acoustic metamaterial according to the effective elastic wave amplitude range and determine the use environment of the nonlinear acoustic metamaterial. The present application can improve the calculation accuracy of the bandgap characteristics of the nonlinear acoustic metamaterial, and determine the use environment of the nonlinear acoustic metamaterial according to the effective elastic wave amplitude range, so as to achieve vibration reduction and noise reduction and improve the performance of structural components.

The application discloses a semi-blind source separation method for nonlinear acoustic echo cancellation. The method comprises the following steps: (1) obtaining a microphone signal containing nonlinear echo to be processed; (2) performing basis function expansion on a nonlinear mapping input signal, and obtaining a time-frequency domain observation model by using a short-time Fourier transform based on a convolution transfer function approximation, so as to obtain a semi-blind source separation model for nonlinear acoustic echo cancellation; (3) according to the semi-blind source separation model, realizing semi-blind source separation of the signal based on an auxiliary function independent vector analysis method or an independent low-rank matrix analysis method, optimizing a separation matrix, and separating out a near-end time-frequency domain signal; and (4) obtaining a time-domain near-end signal by using an inverse short-time Fourier transform. The method has effective nonlinear echo cancellation performance.

A numerical modeling method for an underwater complete axial symmetry space three-wave coupling sound field belongs to the field of nonlinear acoustics, and comprises the following steps: carrying out simple harmonic hypothesis on sound waves, and substituting the sound waves meeting difference frequency three-wave frequency matching conditions into a KZK equation to obtain a difference frequency three-wave coupling equation set; decomposing the equation set into a diffraction equation, a dissipation equation and a nonlinear equation by using a second-order Strong operator splitting method; a diffraction equation is solved by using a chasing method, a dissipation equation is solved by using an accurate analytical solution, and a nonlinear equation is solved by using an explicit Euler method; and setting boundary conditions, and calculating an underwater complete axial symmetry space three-wave coupling sound field. According to the method, a three-wave coupling sound field model is established based on a KZK equation, efficient solving of a three-wave coupling equation set is achieved by utilizing a second-order Strong operator splitting method and combining finite difference and an explicit Euler method, and the three-wave coupling sound field in the underwater complete axial symmetry space is accurately calculated. According to the invention, the calculation complexity is reduced, the calculation efficiency is improved, and the calculation result is accurate.

The application discloses a high-power ultrasonic focusing transducer with adjustable focus, belongs to the technical field of transducers, and relates to a concentric ring built-in nonlinear acoustic field focusing system, the nonlinear acoustic field focusing system is electrically connected with the concentric ring piezoelectric element, the nonlinear acoustic field focusing system provides a driving electric signal for the concentric ring piezoelectric element, sound waves are generated on the ceramic sheet, the sound waves emitted by adjacent ceramic sheets cross to form a focus point focusing on the pathological tissue, and dynamic superposition of multi-frequency signals is generated. Different moving depths of the ceramic sheets moving simultaneously are used to break the focus point formed by the sound waves emitted by the originally static ceramic sheets and to generate a combined focus point of multiple frequencies again, so that dynamic enhancement of the focus points at different depths is realized. The application not only realizes focusing on pathological tissues at different depths, but also realizes more accurate and stronger focusing, and the pathological ablation effect is better.

This invention discloses a logging probe anti-sticking and retrieval system and method based on negative Poisson's ratio materials. Unlike typical positive Poisson's ratio materials, the outstanding mechanical property of negative Poisson's ratio materials is that when subjected to compressive load in a certain direction, they do not exhibit compressive characteristics in the vertical direction, but rather compressive characteristics. Therefore, when subjected to compressive loads, the negative Poisson's ratio material structure can exhibit overall volume reduction, without compressing adjacent mechanical equipment or geological structures, making it particularly suitable for downhole anti-sticking technology. Simultaneously, by combining a piezoelectric ultrasonic transducer and utilizing the nonlinear acoustic elasticity effect of solid media, the propagation characteristics of ultrasonic waves inside the negative Poisson's ratio material probe subjected to compressive loads will change accordingly. This allows for the assessment of the magnitude of the environmental compressive load and the degree of sticking risk, facilitating quantitative analysis by the control system and enabling retrieval action decisions. Combined with the anti-sticking control system and anti-sticking retrieval device, the logging instrument can be retrieved.

This invention relates to a non-destructive testing method, system, and equipment for the burial depth of utility poles based on nonlinear acoustic features. The testing method includes: S1, applying a broadband transient impact excitation to the sidewall of a concrete utility pole to induce a vibration response in the dominant resonant mode; S2, simultaneously acquiring the force signal of the impact excitation and the acceleration signal of the vibration response to obtain a time-domain response signal; S3, extracting nonlinear acoustic features from the response signal, including at least one of higher harmonic features and resonant frequency shift features; S4, inputting the extracted nonlinear acoustic features into a calibrated regression model to output a quantitative index characterizing the degree of delamination damage at the steel-concrete interface in the concrete utility pole. This invention overcomes the limitation of existing linear acoustic methods, which can only qualitatively judge severe damage, and enables early detection and quantitative assessment of hidden damage such as early delamination and microcracks at the steel-concrete interface.

This invention belongs to the field of nonlinear acoustics technology, specifically relating to a method, program, equipment, and storage medium for calibrating the amplitude and phase consistency of parametric arrays. This invention determines and compensates for the difference-frequency amplitude and phase response of the high-frequency acoustic waves emitted by each array element, thereby enabling the calibration of the amplitude and phase consistency of parametric arrays in various experimental scenarios such as water tanks and anechoic chambers. This invention exhibits high robustness to installation errors, and the calibrated array elements possess a more consistent difference-frequency amplitude and phase response. The invention has a simple implementation, is applicable to various experimental scenarios, and provides necessary pre-calibration for beamforming of parametric arrays, possessing high application value.

A sum frequency wave suppression method under underwater acoustic pulse three-wave mixing belongs to the field of nonlinear acoustics, and comprises the following steps: performing time integration on a KZK equation, and converting the KZK equation into a TBE equation by using generalized traveling wave transformation; dividing the TBE equation into four partial differential equations according to physical meanings by utilizing an operator splitting thought; the X-direction diffraction equation, the Y-direction diffraction equation and the dissipation equation are all solved by adopting a finite difference method, and the nonlinear equation is solved by adopting linear interpolation; setting initial conditions and boundary conditions; setting a sound source boundary condition to send a pulse signal, and adding a phase factor in a pulse signal expression; and changing the phase factor to obtain sum frequency wave suppression and difference frequency wave enhancement under the optimal phase factor. According to the method, the KZK equation is solved through the time domain, the sound field under the first-class pulse three waves is accurately described, and powerful support is provided for follow-up further research on influence factors of the sum frequency sound field and the difference frequency sound field. According to the invention, the difference frequency wave energy can be increased by 5dB at most.

The invention relates to the technical field of marine acoustic detection, in particular to a buried shellfish density detection nonlinear sonar system based on penetration inversion. Comprising a signal transceiving unit; a motion compensation unit; a data fusion module; a signal processing unit; a data resolving unit; and a control unit. According to the method, the spatial resolution of the shellfish micro shell structure is improved by utilizing the second harmonic, and collaborative optimization of the penetration depth and the resolution is realized; based on the characteristic that resonant frequency and reflected harmonic characteristics of a thin shell structure of a shellfish shell are distributed in a higher frequency band, a broadband nonlinear signal containing second harmonics is generated through a signal generator, and a characteristic extraction module extracts multi-dimensional nonlinear acoustic characteristics such as a ratio of second harmonic energy to fundamental wave energy, a signal phase mutation coefficient and the like; an acoustic reflection signal of the shellfish shell can be effectively excited; through the motion compensation unit, high-frequency surge disturbance in a shallow water area can be effectively dealt with.