514 results about "Wavenumber" patented technology

The invention discloses a road cavity volume calculation method and device based on a three-dimensional FK migration algorithm, equipment and a medium, and relates to the technical field of road cavity detection, and the method comprises the steps: obtaining three-dimensional ground penetrating radar data, and carrying out the preprocessing of the data, and obtaining target radar data; converting the target radar data to a frequency wavenumber domain to obtain frequency wavenumber domain radar data; establishing a road hierarchical velocity model, and performing hierarchical wave field extrapolation and double weight correction based on the frequency wave number domain radar data and the road hierarchical velocity model to obtain corrected wave field data; performing sparse constraint optimization imaging processing on the corrected wave field data to obtain a target imaging result; and carrying out boundary extraction processing on the target imaging result to obtain a three-dimensional cavity boundary point set, and carrying out voxelization processing based on the three-dimensional cavity boundary point set to obtain a road cavity volume. According to the invention, high-precision restoration of the shape of the road cavity and automatic extraction of the volume can be realized in three-dimensional GPR imaging.

The invention relates to the technical field of pipeline detection, and provides a non-contact pipeline fluid flow velocity measurement method based on a frequency wavenumber domain spatial spectrogram, and the method comprises the steps: collecting a turbulence signal in a pipeline through a piezoelectric film sensor; carrying out snapshot number segmentation on the turbulence signal to obtain a plurality of segmented turbulence time domain signals; fourier transform and narrowband signal processing are carried out on the segmented turbulence time domain signals, and a spatial spectrum corresponding to each narrowband signal component is obtained; constructing a three-dimensional frequency-wave number domain spectrogram according to the spatial spectrum function; and according to the three-dimensional frequency-wavenumber domain spectrogram, calculating the flow velocity of the pipeline fluid. According to the method, a three-dimensional spectrogram characteristic space is constructed through conjoint analysis of the frequency and the wave number, the angle, distance and frequency characteristics of the turbulence signals are decoupled through spatial spectrum estimation methods such as the MUSIC algorithm, multipath interference and noise are effectively restrained, the flow speed of fluid in a pipeline can be accurately estimated, and limitation in a traditional method is overcome.

The invention relates to a near-surface defect positioning method based on a laser ultrasonic surface wave, which comprises the following steps of: extracting a defect tiny inverse signal and calculating reflection time delay by utilizing a high-frequency surface wave signal excited by laser through a wavenumber domain method to determine a defect position, and determining the burial depth of the defect through a reflection wave amplitude value of the defect; comprising the steps of S1, laser ultrasonic finite element simulation; s2, acquiring high-frequency laser ultrasonic signals; s3, direct wave and reflected wave extraction and time delay calculation; s4, determining defect space coordinates; and S5, determining the burial depth of the defect. The method makes full use of the advantages of high frequency and long propagation distance of surface waves, can effectively solve the problem of defect detection and positioning of the tested piece, can quickly detect the submillimeter defects, is high in positioning precision, and is suitable for positioning and detecting the submillimeter defects on the near surface of a structure.

The invention discloses a near-fault broadband strong vibration simulation method, which comprises the following steps: S1, data collection and preprocessing: collecting a small vibration record in a research area as a source of an empirical Green function, and simultaneously obtaining information such as a geologic structure and stratum parameters of the area for model construction of a discrete wave number method; s2, correcting an empirical Green function, and selecting records similar to a target earthquake focus mechanism from the collected small earthquake records; and S3, calculating based on a geological structure and stratum parameters of a research area by using a discrete wavenumber method. According to the near-fault broadband strong vibration simulation method, the advantages of the two methods are fused, the description of the discrete wave number method on the medium structure at the low frequency band is accurate, the corrected empirical Green function can consider more actual factors at the high frequency band, accurate simulation of the broadband is achieved, and small vibration records are used as the empirical Green function, so that the simulation accuracy of the near-fault broadband strong vibration simulation method is improved. And information such as a real field effect is included, so that a simulation result is closer to an actual seismic oscillation condition.

The invention provides synthetic aperture sonar equipment towed by an unmanned aerial vehicle and a method, and belongs to the technical field of underwater sonar detection. The equipment comprises an unmanned aerial vehicle, a sonar towed body, a towing cable and a water surface control unit, the method comprises: establishing a measurement reference; based on the measurement basis, acquiring state data of the synthetic aperture sonar under the dragging of the unmanned aerial vehicle, and resolving in real time to obtain pose data; extracting a track direction velocity component from the pose data, performing displacement integration on the track direction velocity component, and generating a pulse trigger signal when the displacement integration quantity reaches a sound wave half-wavelength threshold value; synchronously latching current pose data and collecting acoustic echoes based on the pulse trigger signal, and generating a timestamp binding data packet; geometric phase compensation is applied to the timestamp binding data packet, an aliasing-free image is reconstructed through wave number domain resampling, and spatial spectrum aliasing caused by carrier motion disturbance is eliminated.

The invention relates to an unsteady-state sea wave direction spectrum estimation method. The method comprises the steps of S1, signal decomposition; s2, direction distribution calculation; s3, adaptively adjusting the time domain analysis step length; s4, performing nonparametric kernel estimation on the transient wavelet distribution probability; and S5, direction spectrum time domain adaptive reconstruction is carried out. In the time domain analysis process of wavelet analysis, a two-dimensional plug-in non-uniform bandwidth algorithm is adopted to determine a data-adaptive two-dimensional non-uniform and non-parametric kernel function, the probability of different wavelets in a wave number-direction space is analyzed, the lateral propagation sea wave energy in the non-main wave direction is estimated, and the wave energy in the non-main wave direction is obtained. Therefore, the precision and the anti-noise capability of the direction spectrum estimation method are improved. In the time domain analysis process of wavelet analysis, a sea wave signal fluctuation intensity detection algorithm based on the frequency-direction-wave number three-dimensional change rate of wave energy distribution is introduced, the time duration of sea wave signal sections is divided according to the fluctuation intensity, the time domain precision is adjusted, the calculation efficiency is improved, and meanwhile, the sea wave signals which rapidly change in the time domain are accurately captured. Measurement is avoided.

The invention provides an aero-engine blade damage detection method based on an improved ultrasonic sparse reconstruction algorithm, and relates to the technical field of aero-engine damage detection positioning, and the method comprises the steps: S1, setting a sensor array and a detection region of a to-be-detected blade, and obtaining an actual measurement damage reflection signal dictionary through a sensor; s2, wave number distribution of a detection area is determined according to a variable thickness structure Lamb wave propagation model, signal reconstruction is carried out, and a theoretical damage reflection signal dictionary is obtained; s3, an aero-engine blade damage detection model is constructed, an improved sparse reconstruction algorithm is adopted to solve and optimize, and damage judgment is carried out; and S4, according to the pixel value distribution condition of the aero-engine blade detection area, generating an aero-engine blade damage detection image, and positioning a damage position. According to the method, the reflected wave amplitude information can be obtained from the array sensor signals, and the reflected wave amplitude information is compared with the reconstructed theoretical reflected signals, so that the damage condition of the aero-engine blade is identified and positioned.

The invention provides a method for testing flow-induced noise of a pipeline. The method comprises the following steps: S1, determining measurement positions at an upstream flow channel and a downstream flow channel of a measured element, carrying out normalization processing on measured signals, and calculating the pressure power spectrum density of the inner wall surface of a pipe; s2, calculating a wall surface pressure fluctuation time domain cross correlation coefficient, and analyzing correlation characteristics between wall surface pressure pulsation; s3, spectrum intrinsic orthogonal decomposition is carried out on the pressure pulsation field, and space-time decoupling is achieved through time domain-frequency domain conversion; s4, extracting a dominant flow-induced noise mode, constructing an empirical frequency-wave number spectrum, and decomposing fluctuating energy distribution into contributions of different frequency and wave number combinations; s5, analyzing the decoupled flow-induced noise characteristic result, and identifying the amplitude-frequency characteristic of the flow-induced noise; according to the invention, real-time measurement of pressure pulsation in the pipeline can be realized, decoupling analysis of flow field pulsation and sound pressure pulsation can be carried out on the measured signal, and characteristics and a generation mechanism of pipeline flow-induced noise can be identified.

The invention discloses a multi-scale sea surface electromagnetic scattering calculation method and device based on marine environment elements and a storage medium, and belongs to the technical field of marine detection and physical remote sensing. The method comprises the following steps: calculating a tension wave sea spectrum according to an Elfouhail sea spectrum in combination with a Longuet-Higgins directional spectrum; a JONSWAP sea spectrum is combined with a Longuet-Higgins directional spectrum to calculate a gravity wave sea spectrum; superposing the tension wave on the gravity wave according to the slope by using a linear superposition method, and calculating a self-adaptive cut-off wave number; the contribution of small-scale waves to scattering is calculated by adopting an integral equation method, mirror scattering of large-scale waves is counted by adopting a Kirchhoff approximation method, and statistics and fusion are carried out on each scale wave according to the self-adaptive cut-off wave number, so that an electromagnetic scattering value is obtained. According to the method, a sea surface geometric calculation method based on real marine environment element driving is adopted, and accurate calculation is performed aiming at sea surface scattering characteristics under different sea conditions in combination with an integral equation method-Kirchhoff approximation electromagnetic scattering calculation model of an adaptive cut-off wave number, so that the calculation precision of scattering intensity is improved.

The invention discloses a noise reduction method of a bionic fish scale blade centrifugal pump, which comprises the following steps that a long and short blade centrifugal pump is selected for research, and the main design parameters of the long and short blade centrifugal pump are as follows: the specific speed ns is equal to 40.79, the rated flow Qd is equal to 10.6 m < 3 > / h, the lift H is equal to 34m, and the rotating speed n is equal to 2900r / min; a computational domain three-dimensional model of the long and short vane centrifugal pump is established through Creo8.0; in order to prevent backflow of inlet and outlet sections, ensure that fluid stably flows into an impeller and ensure the accuracy of a simulation result, extension pipelines are additionally arranged at an impeller inlet and a volute outlet of the centrifugal pump, the pipe diameter of the inlet extension section is 4 times that of the outlet extension section, and the pipe diameter of the outlet extension section is 8 times that of the inlet extension section; in order to verify the accuracy of a calculation result, a centrifugal pump experiment platform is built for external characteristic experiments; the bionic fish scale pit has the advantages that the dynamic and static interference between the impeller and the volute is reduced, the pressure fluctuation in the pump is stabilized, the amplitude fluctuation of a wave number-frequency spectrum and the energy region of a low wave number region are reduced, the migration of a wave number-frequency spectrum peak ridge is reduced, the curve change is gentle, and then the noise reduction effect is achieved.

The invention provides a method, a medium and a system for calculating ocean wave spectrum parameters of ocean digital twinning, and belongs to the technical field of electrical digital data processing. The method comprises the following steps: acquiring and preprocessing original sea wave spectrum data, selecting a Jonswap frequency sea wave spectrum as a theoretical model, establishing a multi-index fitting criterion, optimizing and solving a peak rise factor parameter, performing statistical analysis according to a significant wave high period level, and distinguishing sea wave spectrum characteristics of typhoon and non-typhoon working conditions. And calculating the wave amplitude wave number and the random phase to construct a wave surface height model, and finally forming a sea wave spectrum parameter database. The technical problem that sea wave spectrum parameters in the ocean digital twinning system are difficult to accurately describe and calculate is solved, the extreme sea condition simulation capability is particularly optimized, and high-precision sea wave field simulation technical support is provided for the ocean digital twinning system.

The invention provides a high-frequency electromagnetic excitation cable detection image reconstruction method and system, and belongs to the technical field of underground facility multi-field coupling detection and imaging, and the method comprises the steps: applying high-frequency electromagnetic excitation to an underground medium; receiving an electromagnetic signal transmitted through an underground medium, synchronously collecting a sound signal generated by electromagnetic excitation, and preprocessing the electromagnetic signal and the sound signal; performing structure imaging on the electromagnetic signal by adopting a frequency wave number migration imaging algorithm to obtain medium structure distribution; performing electrical parameter imaging on the electromagnetic signal by adopting a Born approximate inverse scattering imaging algorithm to obtain medium electromagnetic characteristic parameter distribution; sound source distribution reconstruction is carried out on the sound signals through a time reversal algorithm, and medium sound source response characteristic distribution is obtained; and inputting imaging results of the three algorithms into a pre-constructed deep reinforcement learning model for dynamic fusion to generate an underground medium comprehensive parameter reconstruction image.

The invention belongs to the field of optical coherence layer imaging, and particularly discloses a spectrum calibration method for a linear field spectral domain OCT (optical coherence tomography) system, which comprises the following steps: acquiring interference signal instantaneous phases corresponding to two optical path differences by adjusting a lifting platform at a sample mirror in the linear field spectral domain OCT system, and subtracting the interference signal instantaneous phases to obtain an instantaneous phase difference; based on the calibration light source, discrete spectral lines are generated on a detector through a sample arm in the shielding line view field spectral domain OCT system, and spectral intensity distribution corresponding to the calibration light source is obtained; calculating the sub-pixel position of the peak value of each spectral line and the instantaneous phase difference corresponding to the sub-pixel position based on the instantaneous phase difference and the spectral intensity distribution corresponding to the calibration light source; and based on the wave number and the instantaneous phase difference corresponding to each spectral line, determining a linear relationship between the instantaneous phase difference and the wave number through linear fitting, and calibrating the corresponding wave number based on the linear relationship. According to the method and the device, the linear field OCT spectrum calibration result with higher precision can be realized.

The invention relates to the technical field of spectrum detection, in particular to a Raman spectrum-based rice oil detection method, which comprises the following steps: extracting main and auxiliary peaks to construct a peak group structure, performing sliding comparison to output a conformity region, identifying jump to remove an abnormal signal, calibrating a peak position to generate a correction structure, and performing homing numbering to complete a detection scheme. According to the method, the feature matching rule is constructed by combining the peak position spacing, the intensity ratio and the wavenumber index, the recognition precision of the multi-peak structure in the spectrum is enhanced, non-continuous response signals are recognized and eliminated through derivative change trend and proportion deviation constraint, and the accuracy of stable response extraction is improved. Dynamic calibration and position adjustment of peak positions are realized by utilizing an offset trend sequence, the consistency of a peak group structure in an overall direction and the continuity of a local structure are ensured, a numbering system and structure attribution division is completed after homing sorting, and the integrity of feature expression in a complex sample and the orderliness and reliability of spectral data processing are improved.

The invention discloses an ultra-deep reflection imaging method based on passive source seismic data and a related device, and relates to the technical field of earth depth structure imaging, and the method comprises the following steps: firstly, for original continuous seismic waveform data, intercepting seismic waveform data with a first arrival of a P wave and a non-arrival of an S wave, and carrying out the preprocessing of the data, so as to obtain a far earthquake event data segment; the method comprises the following steps: firstly, analyzing and identifying a far earthquake event with a high signal-to-noise ratio by using a time-frequency-wavenumber domain, removing data which are greatly influenced by noise, and then, reconstructing a reflection wave field of a high-quality far earthquake data fragment by using a multi-dimensional deconvolution technology, and carrying out convolution on a seismic source wavelet to obtain ultra-deep reflection wave field data. And finally, performing reflection imaging processing in combination with velocity analysis and superposition imaging technologies, optimizing the analysis capability of a deep reflection interface, and finally obtaining an earth deep reflection imaging profile, so that a continuous structure interface extending from the shallow earth crust to the deep mantle can be clearly revealed, and coupling characteristics between shallow and deep earth structures can be effectively captured.

The invention discloses a method for generating a reflection angle domain point spread function based on an LSTM network, and belongs to the technical field of geophysical exploration, and the method comprises the following steps: S1, selecting a reference point, and constructing a label through ray tracing and wave equation forward modeling; s2, training an LSTM (Long Short Term Memory) network as a ray tracing agent model of the whole space of an imaging domain; s3, predicting a travel time gradient and an amplitude factor through a ray tracing agent model; s4, combining the seismic source and the geophone in pairs, and calculating a reflection angle through the travel time gradient; s5, solving an illumination wave number vector, and solving a wave number domain point spread function in combination with the illumination intensity; s6, performing inverse Fourier transform on the wavenumber domain point spread function to obtain a spatial domain point spread function; and S7, solving a deconvolution problem to optimize the angle gather. According to the method, the calculation efficiency of solving the Green function through seismic wave ray tracing can be improved, the imaging response described by the point spread function is eliminated from the imaging result, and the balance of the resolution of the imaging result and the illumination intensity can be improved.

The present invention relates to the technical field of seismic exploration. Provided are a three-component seismic data vector anti-aliasing interpolation reconstruction method and an apparatus. The method comprises: representing three-component seismic data in a time domain as pure quaternions for vector joint; transforming the pure quaternion data in a time-space domain to a frequency-space domain to obtain frequency-space domain data; transforming the frequency-space domain data into a frequency-wave number domain; in the frequency-wave number domain, using an inclination angle scanning strategy to construct a mask matrix; performing vector anti-aliasing interpolation reconstruction on the frequency-space domain data and the mask matrix, so as to obtain a frequency-space domain reconstruction result; and inversely transforming the frequency-space domain reconstruction result to the time-space domain to obtain a time domain three-component three-dimensional data anti-aliasing reconstruction result. The present invention can effectively solve the problem of vector anti-aliasing reconstruction for three-component seismic data that contain both irregular and regular missing traces, thus improving the accuracy of effective wave event identification.

The invention discloses a real-time wave number space resampling method and system for SS-OCT, and relates to the technical field of signal processing, and the method comprises the steps: synchronously collecting a K clock signal and an OCT interference signal, and carrying out the filtering preprocessing of the signals; carrying out Hilbert transformation on the preprocessed K clock signal, constructing an analysis signal, extracting an instantaneous phase, and forming an instantaneous phase sequence; using a preset ideal equal wave number interval phase sequence as a target phase sequence, matching the target phase sequence with the instantaneous phase sequence, calculating a corresponding position index of each target phase in the instantaneous phase sequence, and obtaining a remapping sampling point index; and processing the preprocessed OCT interference signal by using an SINC interpolation method according to the remapping sampling point index to obtain an OCT signal which is subjected to resampling and has equal wave number intervals. According to the invention, the SINC interpolation algorithm is utilized to complete resampling in real time and with high precision in the data acquisition stage, and the requirement of high-speed real-time imaging is met.

The invention discloses a mobile underwater acoustic communication multipath channel modeling method based on sound field calculation, and relates to underwater sound waves. Channel modeling is carried out by inputting environmental parameters including an ocean sound velocity profile, submarine topography and the like, and modeling parameters including initial coordinates, motion trail equations and the like of a signal transmitting end and a signal receiving end. Performing ocean sound field calculation by adopting a ray tracing model, a normal wave model or a wave number integral model and the like, and calculating a sound field at each track sampling moment according to modeling parameters. And converting a frequency domain sound field result into a channel impulse response through inverse Fourier transform, and recovering the time-varying impulse response of the whole multipath channel by using local spline interpolation. And carrying out convolution on the transmitted signal and the time-varying impulse response of the multipath channel, and adding common propagation time delay to obtain a received signal simulation result. Through accurate sound field calculation and multipath channel modeling, the signal transmission condition in a specific marine environment can be simulated without actual marine environment measurement, the marine actual measurement cost is reduced, and the research and development efficiency is improved.

The invention discloses a three-dimensional seismic simulation method based on a residual Fourier neural operator. The invention provides an embedded physics data-driven deep learning seismic wave field simulation technology. According to the method, a Fourier wave propagation operator structure is embedded into a convolutional neural network structure, and wave propagation simulation is alternately carried out in a spatial domain and a wavenumber domain. Due to the fact that the network structure conforming to the wave field propagation mode is adopted, and the implied wave field propagation mechanism in the data can be automatically met, the efficiency of the deep learning seismic simulation method is greatly improved, the requirements of the deep learning seismic simulation method for the training data volume and the training time are reduced, and meanwhile the generalization performance of a deep learning model can be enhanced. Compared with a classic finite difference numerical solution, the method has the advantages that the operation efficiency is higher, the occupied storage space is smaller, the method is not restrained by the space grid size and the time step length, and the method is more suitable for large-range high-frequency complex medium seismic wave simulation requirements.

The invention relates to the technical field of signal processing, in particular to a pipeline guided wave signal processing method and system. The method comprises the following steps: acquiring a multi-channel ultrasonic guided wave signal through a sensor array circumferentially arranged around a pipeline, and converting the multi-channel ultrasonic guided wave signal into a frequency domain response matrix; calculating a circumferential amplitude distortion degree based on the power spectrum amplitude distribution of each channel; constructing a modal coupling matrix by combining the circumferential amplitude distortion degree and the theoretical wave number of the ideal pipeline; correcting the standard orthogonal modal matrix to generate a modal projection matrix; and decomposing the frequency domain response matrix by using the projection matrix, and separating a structure echo component and a defect signal component. According to the method, the influence of geometric defects such as ovality deviation is evaluated more accurately, energy exchange between modeling modes is accurately established, and orthogonality hypothesis is corrected; modal energy leakage is inhibited, and the decomposition accuracy is improved; signals are effectively separated, coherent noise interference is solved, and the accuracy and reliability of pipeline defect detection are improved.

The invention discloses a multi-scale fractured porous medium rock physical modeling method and device. The method comprises the following steps: determining an elastic modulus of an equivalent rock containing pores and microscopic cracks by utilizing an equivalent medium model based on respective elastic moduli and geometric factors of a mineral matrix, the pores and the microscopic cracks; on the basis of the elastic modulus of the equivalent rock containing the pores and the microscopic cracks, determining the elastic modulus of the equivalent rock containing the extrusion jet effect of the microscopic cracks; based on the elastic modulus of the equivalent rock containing the microcosmic fracture extrusion jet flow effect, the far-field scattering amplitude caused by each group of mesoscopic fractures is determined, the total far-field scattering amplitude caused by all the mesoscopic fractures is obtained, and the total effective longitudinal wave number is determined; and according to the total effective longitudinal wave number, establishing a multi-scale fractured porous medium rock frequency dispersion and attenuation model. According to the method, the frequency dispersion and attenuation model comprehensively considering the crack scale effect and the frequency dispersion characteristic can be established.

The invention discloses a two-stage Raman hyperspectral imaging method, which relates to the technical field of spectral signal analysis and comprises the following steps: S0, preprocessing Raman hyperspectral data to remove abnormal values; the method comprises the following steps: S1, taking a wave number where a target characteristic peak is located as a target wave number, and based on a neighborhood of the target wave number in Raman hyperspectral data, performing spectrum denoising on the Raman hyperspectral data by using an adaptive low-rank matrix approximation algorithm to obtain the Raman hyperspectral data after spectrum denoising; and S2, using an improved BM3D method based on a rotating block to carry out image denoising on a Raman image after Raman imaging is carried out on a target wave number in the Raman hyperspectral data after spectrum denoising. According to the method, the neighborhood of the target wave number is used as the target area, the adaptive low-rank matrix approximation algorithm is used for spectrum denoising, then the improved BM3D method based on the rotating block is used for image denoising, Raman hyperspectral fast and efficient imaging is achieved, and the method has the advantages of being good in denoising effect, high in speed and light in weight.

The invention discloses a Fourier finite difference deconvolution imaging method based on inclination angle adaptive noise suppression, and relates to the technical field of geophysical exploration of petroleum. The method specifically comprises the following steps: designing a scattering point speed model to solve a partial point spread function of an underground space; solving a partial point spread function by a speed disturbance method; solving point spread functions of all positions of the underground space by carrying out Gaussian filtering technology and inverse distance weighted interpolation on part of the point spread functions; using a plane wave destruction method to solve the inclination angle attribute of the work area, and constructing an inclination angle self-adaptive diagonal diffusion Fourier finite difference migration method based on the inclination angle attribute to solve a high-quality initial image suitable for an inversion system; and performing multi-dimensional deconvolution in the wave number domain to obtain a final migration imaging result. According to the method, the point spread function is successfully introduced into Fourier finite difference imaging, and the resolution and deep amplitude of a conventional Fourier finite difference imaging method can be effectively improved.

The invention discloses a modal decomposition-based target motion velocity estimation method and a sound velocity profile inversion method, and the method comprises the following steps: 1, obtaining a two-dimensional frequency domain sound field, obtaining a normal wave vertical mode function through singular value decomposition, and obtaining a normal wave horizontal wave number through Fourier transform; 2, substituting the normal wave vertical mode function and the normal wave horizontal wave number into a mode difference equation to obtain a sound velocity profile estimated by each normal wave mode; and step 3, setting a loss function for measuring similarity between sound velocity profiles corresponding to each normal wave mode, setting a target motion velocity search interval, scanning the target motion velocity search interval, and taking a velocity value corresponding to the minimum loss function as a target motion velocity estimation value. According to the invention, target motion velocity estimation and sound velocity profile inversion in an unknown marine environment are realized by using a narrow-band signal radiated by a moving target.

The invention relates to a frequency domain full-focus imaging method, in particular to a frequency domain full-focus imaging method for bolt thread detection. The invention aims to solve the problems of huge data volume and long imaging time of a time domain full-focus algorithm image generation technology. According to the method, an ultrasonic phased array is used for detecting bolt crack defects, and a three-dimensional echo signal matrix of all transmitting / receiving combinations is obtained; then three-dimensional Fourier transform is carried out, and a time domain and a space domain are converted into a frequency domain and a wavenumber domain; the emission wave number is kept unchanged, a new wave number value is calculated through Stolt mapping interpolation, two-dimensional slices are extracted and superposed, and scatterer distribution of the target area after two-dimensional Fourier transform is obtained; and finally, carrying out two-dimensional inverse Fourier transform to obtain an ultrasonic image. The invention belongs to the technical field of frequency domain full-focusing imaging.

This paper provides a high-resolution frequency-wavenumber method capable of modal separation. Based on the frequency, wavenumber, and phase velocity characteristics of multimodal Rayleigh surface waves, a method for enhancing high-modal energy by weighting the F-K spectrum with a two-dimensional Gaussian window is proposed. This algorithmic approach enhances high-modal Rayleigh wave information, resulting in simple computation and clear physical meaning. Using probability distribution statistics, a frequency-phase velocity probability distribution is plotted. All extreme points are statistically analyzed, and the median of their phase velocity intervals is taken as the phase velocity of the frequency point in that mode. This more accurately separates and extracts multimodal dispersion curves.

The invention provides an anti-noise interference frequency parameter estimation method for high-precision optical coherence ranging, which comprises the following steps: acquiring a spectral interference signal of an optical low-coherence interference system and a reference light spectral signal output only by a reference arm, and converting the spectral interference signal into interference signals with wave number space arranged at equal intervals, carrying out spectral density amplitude normalization to obtain a standard interference signal so as to eliminate interference of light source spectrum fluctuation and non-uniform sampling on frequency estimation; hanning window modulation is applied to a standard interference signal, spectrum leakage is suppressed, spectrum analysis is performed on the modulated signal, a peak value and an adjacent secondary peak value of a spectrum main lobe are extracted, a frequency correction amount is calculated based on a peak value and secondary peak value amplitude ratio relation derived by a Hanning window spectrum mode function, and an accurate frequency of the interference signal is obtained; and calculating the displacement of the object to be measured according to the product of the accurate frequency and the spectral resolution of the optical low-coherence interference system in combination with the refractive index of the light in the measurement medium.

The invention relates to a zero Doppler clutter analysis and near-field millimeter wave imaging method based on an elliptical array, and the method comprises the steps: enabling the elliptical array designed based on zero Doppler clutter analysis to irradiate a target, obtaining original echo data, and converting the original echo data into data under an elliptical coordinate system; performing two-dimensional Fourier transform on the data under the elliptic coordinate system to generate data on a wavenumber domain; performing phase compensation on the data on the wavenumber domain; carrying out one-dimensional inverse Fourier transform on the wavenumber domain data after phase compensation; converting the wavenumber domain data in the elliptical coordinate system into a Cartesian coordinate system; and integrating at least one target wave number domain data, and performing three-dimensional inverse Fourier transform on the reconstructed images of all the wave number domains to generate a final near-field millimeter wave imaging result of the elliptical array. According to the embodiment of the invention, the inherent ZDC suppression effect of the elliptical array imaging system is explored, a traditional circular array imaging system is replaced, and the trouble of the ZDC to the traditional circular array imaging system is solved while the high irradiation area is realized. Therefore, the problems that imaging intensity distribution is not uniform, the requirement for the number of array elements is high, and imaging has obvious ZDC artifacts in the prior art are solved.

The invention discloses a deep strike-slip fracture fracture zone identification method, and the method comprises the steps: converting original seismic data into a frequency-wavenumber domain through Fourier transform, carrying out the multi-scale decomposition and downsampling through a radial filter cascade architecture, converting the data into a time-space domain through a directional basis filter, and carrying out the filtering. And acquiring an optimal direction by adopting an optimization strategy, and constructing characterization attributes based on neighborhood attribute differences to extract multi-scale fracture attributes. And introducing a plurality of level set functions to construct an energy functional model, and solving through a dynamic weight adjustment algorithm to realize internal and external band identification. And constructing a model by means of a topological relation based on distance-angle constraint to analyze the three-dimensional space topology. The problems that traditional data processing is not fine and model analysis is insufficient are solved, accurate recognition of the deep strike-slip fracture fracture zone is achieved, and the method has important application value in the fields of oil and gas exploration and development and the like.