53 results about "Forward wave" patented technology

The present application relates to the technical field of seismic data imaging and migration in geophysical prospecting for petroleum. Provided are a multi-wave migration imaging method and apparatus based on an iterative deconvolutional imaging condition. The method comprises: acquiring a seismic wave forward wave field and a seismic wave reverse wave field; using a deconvolutional imaging condition to perform multi-wave imaging on the seismic wave forward wave field and the seismic wave reverse wave field so as to obtain an initial imaging result; taking the seismic wave forward wave field, the seismic wave reverse wave field and the initial imaging result as inputs, using an iterative deconvolutional imaging method to perform multi-wave imaging, so as to obtain an iterative deconvolutional multi-wave imaging result; during the multi-wave imaging, determining an objective function value of the deconvolutional imaging; if the objective function value does not meet a preset condition, iterating the imaging result until the objective function value of the deconvolutional imaging meets the preset condition, and generating a final iterative deconvolutional multi-wave imaging result according to an imaging result obtained after iteration.

The invention relates to an elastic wave full waveform inversion method based on an optimal transmission function, and belongs to the field of seismic velocity modeling. The method comprises the following steps: firstly, establishing an observation system, selecting an excitation source with a certain frequency and a speed model, and receiving an actual seismic record and a simulated seismic record through the excitation source; secondly, introducing an optimal transmission function as a target function of inversion, and establishing a target functional formula; a timing wave field and a reverse time wave field are obtained through forward modeling and reverse time continuation, derivation is carried out on a target functional formula to obtain a gradient calculation formula, the gradient calculation formula is substituted into the timing wave field and the reverse time wave field, and the gradient is obtained. And optimizing the obtained gradient by using an Adam gradient optimization algorithm, and substituting the optimized gradient into iterative inversion to update the model. And repeating the steps until an inversion result meeting the precision requirement is obtained. Model experiments show that compared with a traditional L2 objective function, the method has the advantages that the event continuity of the inversion model is enhanced, the deep structure is clearer, and the overall precision is greatly improved.

The invention provides an orientation and imaging method and system for sound wave detection data in a tunnel hole, and the method comprises the steps: obtaining sound wave data in different directions responding to the same excitation sound wave, rotating the sound wave data until an orthogonal component disappears, and determining the direction of a reflector according to a rotation angle; carrying out weighted summation on the sound wave data acquired by the receiving array to obtain scalar output, calculating an optimal weight to receive a target signal from a reflector orientation to the greatest extent, and carrying out weighted processing according to the optimal weight to obtain a superposed signal; and solving a three-dimensional elastic wave wave equation based on the processed superposed signal to obtain a forward wave field and a reverse wave field, and performing migration imaging by using a cross-correlation imaging condition to obtain a three-dimensional migration imaging result. The method can enhance the signal-to-noise ratio of the weak reflection signal, and achieves the quick and accurate judgment of the orientation of the target body in front of the tunnel face.

The invention belongs to the technical field of tunnel engineering geophysical prospecting, and particularly relates to a full-wave-field tunnel advanced prospecting method based on rock physical constraint, which comprises the following steps of: constructing an initial geologic model, sampling on an upper interface of a layer section where a tunnel is located and carrying out longitudinal and transverse wave velocity measurement to obtain a longitudinal wave velocity Vp and a transverse wave velocity Vs; combining all sampled longitudinal wave velocities Vp and transverse wave velocities Vs, calculating longitudinal wave velocities and transverse wave velocities of a target layer section, obtaining elastic parameters of the target layer section, importing the obtained elastic parameters into an initial geologic model, obtaining a parameter inversion initial model, constructing a forward wave field and a simulated seismic record, and making a difference between an actual observation record and a simulation record, so as to obtain an initial geologic model; and conjugate gradient inversion is carried out. According to the method, all wave field information excited by the shield tunneling machine is fully utilized, and high-precision parameter inversion is carried out under rock physical constraints, so that more accurate tunnel front geological prediction can be provided, and a scientific basis is provided for safe and efficient construction of the shield tunneling machine.

The invention discloses an ultrasonic imaging method for a complex-surface multilayer anisotropic composite material. The method comprises the steps that an acoustic propagation model is established according to profile characteristics of the composite material, acoustic anisotropy characteristics changing along with the appearance and a preset ultrasonic detection mode, and the acoustic propagation model comprises medium attribute information of all spatial positions of the composite material and position and geometric information of an ultrasonic excitation unit and an ultrasonic receiving unit; for the acoustic propagation model, performing excitation in the preset ultrasonic detection mode, and obtaining an excitation signal waveform and a received acquisition signal waveform; and on the basis of the excitation signal waveform and the acquisition signal waveform, positive wave field information and reverse wave field information are calculated, and then a self-defined target is used for reverse time migration imaging to obtain an imaging result. According to the invention, full-depth synchronous focusing imaging in an anisotropic and complex molded surface coupling scene can be realized, and the imaging effect is improved.

The present disclosure, calculating an impedance change considering a reflected wave due to IMD, provides an impedance matching device for performing impedance matching between a source power supply side and a load side, including: a detector that detects a forward wave power supplied from the source power supply and a reflected wave power from the load and outputs a forward wave voltage as a component of the forward wave power and a reflected wave voltage as a component of the reflected wave power, an impedance information output part that calculates impedance from the forward wave voltage and the reflected wave voltage, and a matching part that performs matching operation based on an impedance value supplied from the impedance information output part. The impedance information output part complexifies each of the forward wave voltage and the reflected wave voltage to calculate an impedance value to generate an impedance locus.

The invention relates to the field of exploration geophysics, and discloses a wave equation inversion method for constructing a middle-deep part background velocity field, which comprises the steps of S1, inputting observation gun record data and an initial velocity model, S2, performing forward modeling on the initial velocity field to calculate a forward propagation wave field, and performing back propagation on observation data to calculate a back propagation wave field; s3, calculating and simulating primary reflected wave data according to the migration imaging result and the initial velocity field back migration, solving a data residual error by using an optimal transmission distance, constructing an adjoint source, substituting the adjoint source into reflected wave inversion, calculating a gradient under the optimal transmission measure, and calculating a gradient under the optimal transmission measure; and S4, iteratively updating the background velocity field according to the calculated gradient, and performing full-waveform inversion by using the background velocity field information to obtain a final high-precision inversion result. Wave field residual errors are extracted more accurately based on an optimal transmission distance strategy, and background field gradient information more conforming to an underground structure is constructed.

An electronic device may include signal transmission circuitry having a signal path and a signal source that transmits a signal on the signal path. First and second signal couplers may be coupled to the signal path. Control circuitry may use the first signal coupler to measure the signal at a first reference plane and may use the second signal coupler to concurrently measure the signal at a second reference plane. The signal measurements may include power wave, forward wave, reverse wave, impedance, and / or delivered power measurements. Terminations in the signal couplers may be adjusted to dynamically shift the reference planes. The first and second signal couplers may be formed from first and third metallization layers on a stacked dielectric substrate, where the signal path is formed from a second metallization layer. Additional signal couplers may be coupled to the signal path for concurrently measuring additional reference planes.

A reflective focusing-based depth-velocity modeling method, relating to the field of seismic exploration, comprising: determining an actual seismic record and an initial velocity model (S1); on the basis of a seismic observation system, performing forward simulation on the initial velocity model, and obtaining forward wave field data (S2); on the basis of the actual seismic record and the forward wave field data, calculating a focusing function of a reflected wave residual response, calculating a Green's function of the reflected wave residual response on the basis of the focusing function, and, on the basis of the Green's function and the forward wave field data, calculating a gradient of an objective function with respect to a longitudinal wave velocity (S3); determining an updated velocity model on the basis of the gradient of the objective function with respect to the longitudinal wave velocity and an update step size (S4); and on the basis of the actual seismic record and the updated velocity model, determining whether a termination condition has been met (S5), if so, using the finally obtained updated velocity model as a depth-velocity model, and if not, re-performing forward simulation and the following steps. Further related is a reflective focusing-based depth-velocity modeling apparatus.

The invention relates to the technical field of inverter fault diagnosis, in particular to an inverter fault diagnosis method, device and system, and the method comprises the steps: obtaining the three-phase current data of each moment outputted by an inverter in each period; obtaining a forward wave crest of any phase in each period; determining a wave crest abnormal coefficient of any phase of current in each period; determining the wave crest area ratio of each forward wave crest of any phase in each period; determining a waveform abnormal coefficient of any phase of current in each period; determining a current abnormal coefficient of any phase current in each period; determining the fault sensitivity of any phase of current in each period; and performing fault diagnosis on the inverter based on the fault sensitivity. According to the invention, the fault of the inverter can be detected in real time, and the sensitivity of fault diagnosis of the inverter is improved, so that fault detection can be carried out more accurately.

A high-frequency power supply system according to the present disclosure includes a first power supply, a second power supply, and a first matcher. The first power supply performs frequency modulation control in a second power supply ON period and performs frequency offset control to output a forward wave voltage VF3 having a fundamental frequency F3 obtained by adding an offset frequency to a fundamental frequency F1 in a second power supply OFF period. An optimum value of an initial phase α of a modulation signal is searched for, and an offset frequency Fos at which a difference between a reflection coefficient ρ11 or load-side impedance Z11 corresponding to a center of a locus and a reflection coefficient ρ12 or load-side impedance Z12 is minimum is searched for, and the fundamental frequency F3 in the second power supply OFF period is set.

The invention relates to the technical field of forward wave oscillators, in particular to a K-band TE11 mode microwave oscillator. Comprising a cylindrical waveguide, and sequentially comprises a cut-off transition section, an interaction section and an output transition section, the cathode structure is mounted in the cut-off transition section; the anode waveguide structure comprises a plurality of slotted circular ring metamaterial units which are arranged in the interaction section at intervals in the axial direction, are linked through a metal cylinder to form a serial structure and are connected to the wall of the cylindrical waveguide to form a double-spiral anode slow wave structure; electron beams generated by the cathode structure rotate in the axial direction under the action of an external electromagnetic field, interact with each other in the anode slow wave structure to excite forward waves in a TE11 mode, and radiate outwards along an output transition section; the collector is arranged in the output transition section. On the basis of realizing a Gaussian beam TE11 mode, a traditional mode conversion structure is omitted, the structure is more compact, and light weight and miniaturization are easy to realize.

The application relates to the technical field of bone imaging, and provides an ultrasonic cancellous bone imaging method based on full-wave inversion, which comprises the following steps: S1: setting an imaged bone phantom model, emitting an ultrasonic pulse signal, recording the ultrasonic pulse signal passing through the model, and sampling the signal as a simulation experiment wave field signal; S2: establishing a simulation wave field, setting an initial sound velocity model as a current sound velocity model; S3: based on the current sound velocity model, carrying out forward modeling on the simulation wave field, carrying out incremental extrapolation of the forward wave field signal along the propagation direction of the ultrasonic pulse signal, recording the simulation wave field signal after completing one round of emission-reception; S4: constructing a loss function, solving the loss function by using a conjugate gradient method, and updating the current sound velocity model; and S5: judging whether the loss function converges or not, and outputting the current sound velocity model if the loss function converges. High-resolution ultrasonic imaging of bone and microstructure is realized, and the demand of bone medical treatment and diagnosis with high precision requirements is met.

An electronic device may include signal transmission circuitry having a signal path and a signal source that transmits a signal on the signal path. First and second signal couplers may be coupled to the signal path. Control circuitry may use the first signal coupler to measure the signal at a first reference plane and may use the second signal coupler to concurrently measure the signal at a second reference plane. The signal measurements may include power wave, forward wave, reverse wave, impedance, and / or delivered power measurements. Terminations in the signal couplers may be adjusted to dynamically shift the reference planes. The first and second signal couplers may be formed from first and third metallization layers on a stacked dielectric substrate, where the signal path is formed from a second metallization layer. Additional signal couplers may be coupled to the signal path for concurrently measuring additional reference planes.

The invention provides a PP and PS combined reverse time migration imaging method based on cosine similarity measurement, and the method comprises the steps: 1, obtaining observed seismic data, and extracting seismic wavelets; step 2, calculating a P-wave forward propagation wave field at a seismic source end, a P-wave backward propagation wave field at a detection point end and an S-wave backward propagation wave field at the detection point end; 3, calculating a PP imaging data volume and a PS imaging data volume; 4, calculating the cosine similarity of the PP and PS imaging data volumes; 5, filtering the PP imaging data volume and the PS imaging data volume by using cosine similarity; and step 6, superposing the filtered PP imaging data volume and PS imaging data volume corresponding to all the single shot records, and outputting the PP imaging data volume and the PS imaging data volume. According to the PP and PS combined reverse time migration imaging method based on cosine similarity measurement, the overall quality of PP and PS imaging data volumes is improved, calculation is simple, implementation is easy, high practicability is achieved, and the reliability of the imaging result is high.

A device for estimating bioinformation is provided. The device for estimating bioinformation according to an embodiment of the present disclosure includes: a sensor configured to obtain a biosignal from a subject; and a processor configured to obtain a second-order differential signal of the biosignal and extract a forward wave component from the biosignal based on whether a first local minimum point of the second-order differential signal is stable.

The invention provides an adaptive differential beam forming method and system based on Kalman filtering. The method comprises the following steps: acquiring a forward beam and a backward beam; inputting the forward wave beam and the backward wave beam into a preset Kalman filter, so that the Kalman filter updates a current first Kalman filtering parameter group according to the forward wave beam and the backward wave beam to obtain a second Kalman filtering parameter group, according to the second Kalman filter parameter set, differential beam forming frequency domain signals corresponding to the forward beam and the backward beam are generated, and the Kalman filter is constructed and obtained based on a neural network; and converting the differential beam forming frequency domain signal into a corresponding time domain voice signal to be output, thereby improving the accuracy and adaptability of differential beam forming.

The invention relates to the technical field of power distribution network protection, and discloses a power distribution network protection method and system based on transient traveling wave timing domain characteristic quantity matching, and the method comprises the steps: collecting three-phase voltage data and three-phase current data on a line in real time at a protection installation part, and calculating a current front traveling wave and a current reverse traveling wave; performing wavelet transformation on the current forward traveling wave and the current backward traveling wave, determining the arrival time of the wave head of the first traveling wave in the current forward traveling wave and the current backward traveling wave by adopting a maximum value method, and determining the fault direction; if the fault direction is a forward line fault, acquiring a wavelet transform coefficient of a current backward traveling wave in a preset time period to determine a fault area; and protecting the power distribution network according to the fault area. According to the method, the transient characteristic quantity, namely the fault transient traveling wave, after the fault occurs is adopted, the fault transient traveling wave is only related to the fault and is not influenced by the distributed power supply, and the fault area can be effectively identified under inter-phase non-grounding short circuit and symmetrical metal short circuit faults.

The invention discloses a double-end flexible direct current transmission line protection method based on a line mode voltage forward wave. The method specifically comprises the following steps: calculating the line mode voltage forward wave; solving a valley point of a line mode voltage forward wave in a protection time window, and judging an external grounding fault; identifying a peak value point and a secondary valley value point from the valley value point, and judging whether the protected line has an intra-region grounding fault or not; carrying out special valley value point identification processing on the initial fitting arrays before and after the valley value points to obtain two groups of fitting arrays; performing linear fitting on the two groups of fitting arrays to obtain an included angle between two straight lines and a time axis; and comparing the included angle with a preset external grounding fault setting threshold value and an internal grounding fault setting threshold value, and judging the fault type. The problems that according to an existing line fault protection method, it is difficult to distinguish the ground fault in the line area from lightning stroke interference, and effective recognition of the ground fault in the line area and the ground fault outside the line area cannot be achieved under the low sampling frequency are solved.

The invention discloses a waveguide system for a medical linear accelerator, comprising: a first three-terminal circulator, a second three-terminal circulator, a forward wave sampling waveguide, a reverse wave sampling waveguide and a waveguide; the first three-terminal circulator is used to isolate the reflected wave from entering the waveguide to avoid sparking of the waveguide; the second three-terminal circulator is used to further isolate the magnetron from the waveguide system to ensure stable operation of the magnetron; the forward wave sampling waveguide is used to guide microwaves; the reverse wave sampling waveguide is used to guide microwaves; and the waveguide is used to guide microwaves. The waveguide system for a medical linear accelerator is isolated by two three-terminal circulators. The first three-terminal circulator close to the accelerating tube is used to isolate the reflected wave from entering the waveguide to avoid sparking of the waveguide; the second three-terminal circulator close to the magnetron further isolates the magnetron from the waveguide system to ensure stable operation of the magnetron.

The application discloses a kind of plant fiber reinforced composite based on three-dimensional waveguide wave field's full complex stiffness matrix identification method and system, comprising: narrow-band waveguide excitation is applied to sample and three-dimensional velocity time-domain response signal is collected;Signal is converted to polar coordinate system and modal separation is carried out;Real wave number-frequency pair representing dispersion characteristics and imaginary wave number-frequency pair representing attenuation characteristics are extracted respectively;Based on material structure parameter, establish stiffness matrix method forward wave propagation model and calculate theoretical complex wave number;Two-stage optimization objective function of real and imaginary wave number joint constraint is constructed, and full complex stiffness matrix is obtained by mixed optimization algorithm inversion.This application realizes the decoupling of geometric diffusion and material dissipation by multi-modal three-dimensional wave signal processing and complex wave number separation extraction;Combined with efficient forward model and global-local mixed optimization strategy, the stability and precision of high-dimensional parameter inversion are improved, which can be used for nondestructive testing and viscoelastic parameter accurate identification of plant fiber reinforced composite.

The invention provides a radio frequency power supply phase synchronization method, a phase calibration method and a calibration device thereof. In one embodiment, the radio frequency power supply phase synchronization calibration method comprises the steps of obtaining a phase of a co-excitation input signal, obtaining a phase of a sampling signal, calculating a first phase difference between the sampling signal and the co-excitation input signal, obtaining a phase of a forward wave signal in a load signal, and calculating a second phase difference between the sampling signal and the co-excitation input signal. A second phase difference between the forward wave signal and the co-excitation input signal is calculated, a third phase difference between the forward wave signal and the load signal is calculated, and the third phase difference is calculated based on the load signal and the forward wave signal and the reflected wave signal in the load signal; and calculating a fixed phase difference based on the first phase difference, the second phase difference and the third phase difference, wherein the fixed phase difference serves as a phase synchronization calibration parameter of the radio frequency power supply. The phase synchronization calibration method can realize phase synchronization of the radio frequency power supply output signal and the co-excitation input signal under any load impedance.

The present application relates to a kind of back wave field synthesis processing method, device, computer equipment and storage medium, method includes the following steps: respectively obtaining source back wave data and source wavelet data;According to source back wave data and source wavelet data, determine sparse linear filter coefficient;Using the numerical value of non-zero sparse linear filter coefficient and delay, time delay weighted superposition of forward wave field, synthesis back wave field.The above-mentioned back wave field synthesis processing method, based on source back data is the convolution of source wavelet data and sparse linear filter, determine sparse linear filter coefficient by source back data and source wavelet data, then according to the principle of superposition, time delay weighted superposition of forward wave field, synthesis back wave field.No need to rely on back data to obtain back wave field by solving wave equation, power is greatly reduced, can improve processing efficiency, reduce processing time, can also reduce memory consumption, so as to reduce power cost.

The invention relates to a fault property pre-judgment method and equipment for a multi-terminal flexible direct current selective coincidence line. The method comprises the following steps: judging whether the line has a fault or not; judging an area where a fault occurs; selecting one end from the transmitting end and the receiving end as an injection end according to the fault occurrence area, and controlling the injection end to inject a mixed voltage wave sequence; calculating an injection end line mode voltage fault forward wave; building an equivalent calculation circuit model for lossless traveling wave calculation, and theoretically calculating a fault-free forward traveling wave of the line mode voltage of the injection end; and reconstructing the injection end line mode voltage fault forward wave and the fault-free forward wave, and calculating the Hausdorff distance between the reconstructed injection end line mode voltage fault forward wave and the fault-free forward wave so as to judge the line fault property. According to the method, the overcurrent risk of the direct current circuit breaker or the MMC converter is completely eliminated, the safety of primary equipment is greatly improved, and the method has the advantages of high transition resistance resistance and dead zone fault identification capability.

The invention discloses a power transmission line three-point fault distance measurement method and system, and the method comprises the steps: obtaining the initial fault traveling wave arrival time of all measurement points of a power transmission line when the power transmission line triggers fault distance measurement, and calculating the front traveling wave waveform and the reverse traveling wave waveform of a third measurement point; and judging the direction of an initial fault traveling wave of the third measurement point based on the forward traveling wave waveform and the reverse traveling wave waveform, selecting a distance measurement formula corresponding to the direction, and calculating the distance between the first measurement point and the fault point and the distance between the second measurement point and the fault point by using the distance measurement formula according to the arrival time of the initial fault traveling wave. The approximate position interval of a fault point can be indirectly judged in a mode of calculating a forward wave waveform and a reverse wave waveform, so that a distance measurement formula needing to be used is determined, accurate fault distance measurement can be realized by using the distance measurement formula according to the arrival time of an initial fault traveling wave, and the process does not need to depend on the wave velocity; therefore, the fault distance measurement precision is improved.

The invention discloses a heart-shaped channel positive and negative wave coupling sound production and pickup device. A sound box relates to the technical field of acoustics, and is characterized in that a plurality of sound outlet holes are formed in the front surface of a box body shell along the edge of the box body shell; the loudspeaker unit is embedded in the box body shell and faces the front face of the box body shell, and the other face of the loudspeaker unit is located in the box body shell; the heart-shaped main cavity and the crescent-shaped auxiliary cavity are arranged in the box body shell, the heart-shaped main cavity is arranged on the peripheral side of the loudspeaker unit in a surrounding mode, and the crescent-shaped auxiliary cavity is located below the heart-shaped main cavity. According to the heart-shaped channel positive and negative wave coupling sound production and pickup device, a heart-shaped main cavity is firstly filled with backward waves generated by vibration of a vibrating diaphragm of a loudspeaker unit, and the backward waves enter a crescent-shaped auxiliary cavity through an opening in the apex part of the heart-shaped main cavity according to the physical function characteristics of the heart shape; and the air enters the air through a plurality of small holes distributed in the edge part of the crescent-shaped auxiliary cavity and is coupled with the forward wave of the loudspeaker unit.

The present application belongs to the field of tunnel engineering geophysical prospecting technology, and particularly relates to a full-wave field tunnel advanced exploration method based on rock physics constraints, which comprises the following steps: constructing an initial geological model, sampling at the upper interface of the tunnel layer and carrying out longitudinal and transverse wave velocity measurement to obtain longitudinal wave velocity Vp and transverse wave velocity Vs, combining all the sampled longitudinal wave velocity Vp and transverse wave velocity Vs according to the VRH theory to calculate the longitudinal and transverse wave velocities of the target layer, obtaining the elastic parameters of the target layer, importing the obtained elastic parameters into the initial geological model to obtain a parameter inversion initial model, constructing a forward wave field and simulated seismic record, making a difference between the actual observation record and the simulated record, and carrying out conjugate gradient inversion. The present application can provide more accurate tunnel front geological prediction by fully utilizing all the wave field information excited by the shield machine and carrying out high-precision parameter inversion under the rock physics constraints, thereby providing a scientific basis for safe and efficient construction of the shield machine.

To perform protection control regardless of an output set value of progressive wave power of a repetition period.SOLUTION: The high-frequency power supply device 101 outputs progressive wave power PF having a plurality of levels of power values during a repetition period T to a load, and includes an instantaneous power upper limit setting unit 50 that sets a first instantaneous power upper limit value Pmax, a first output setting unit 60 that sequentially outputs an output power set value Pfset corresponding to an elapsed time, a coefficient setting unit 61 that sets an output power coefficient k within a range in which an average power value during the repetition period does not exceed an average power upper limit value, a multiplication unit 70 that outputs a second instantaneous power upper limit value k·Pmax obtained by multiplying the first instantaneous power upper limit value Pmax by the output power coefficient k, a second output setting unit 80 that outputs a second output set value PFset2 that is a smaller one of the first instantaneous power upper limit value Pmax and the second instantaneous power upper limit value k·Pmax, and an output power control unit 90 that performs control so that a progressive wave power value pf becomes equal to the second output set value PFset2.SELECTED DRAWING: Figure 2

The present invention relates to a full waveform inversion method, device, medium and equipment based on a self-accompanied VTI equation. The method comprises the following steps: splitting a VTI acoustic wave equation and a VTI elastic wave equation to obtain split VTI acoustic wave equation and VTI elastic wave equation; constructing auxiliary variables p and q and introducing them into the split VTI acoustic wave equation and VTI elastic wave equation to obtain a self-accompanied VTI acoustic wave equation and a self-accompanied VTI elastic wave equation; solving the self-accompanied VTI acoustic wave equation and the self-accompanied VTI elastic wave equation to calculate a forward wave field u and predicted data d. pre ; Using the objective function and prediction data d pre Calculate the residual d res Solve the self-adjoint VTI acoustic wave equation and the self-adjoint VTI elastic wave equation, and back-propagate the residual d res Calculate the accompanying wave field u * Based on the gradient formula of the objective function to the model parameters, the forward wave field u and the accompanying wave field u are used to calculate the * Calculate the gradient calculation step size α and update the model m through the gradient and iterative update formula to determine whether the objective function converges.

The invention discloses an earth and rockfill dam hidden danger full-waveform inversion method based on a simulated inter-well observation system, and the method comprises the steps: laying excitation points and detection points at a dam crest and upstream and downstream dam slopes along the cross section of an earth and rockfill dam, and constructing the simulated inter-well observation system to collect seismic data; establishing a hidden-danger-free initial model, performing forward modeling as a current model, and constructing a target function based on observation and simulation records; when the target function value does not reach the preset threshold value, performing wave field back-stepping through the residual record, and calculating the physical property parameter gradient of the current model in combination with the forward modeling wave field; processing by adopting a conjugate gradient method to obtain a conjugate gradient, and then constructing a precondition operator for suppressing surface wave interference and accelerating deep updating in a dam body to correct the precondition operator; and obtaining an optimal inversion step length through step length search, updating the model, and carrying out iteration until an objective function is converged, so as to obtain a physical property parameter model reflecting the earth and rockfill dam hidden danger. According to the invention, the accuracy and inversion efficiency of earth and rockfill dam hidden danger detection can be effectively improved.