78 results about "Wavenumber" patented technology

This invention relates to a method for extracting guided wavenumbers in variable thickness structures, belonging to the field of nondestructive testing technology. It utilizes an excitation signal to generate guided wave signals on the surface of the object under test. Based on a set window function and a set window length, the two-dimensional wavefield signal obtained by sampling the guided wave signal is divided into multiple local wavefield signals. A short-space Fourier transform is then performed on each local wavefield signal to obtain the amplitude-frequency-wavenumber array corresponding to each local space. A frequency range is then selected by summing the amplitude-frequency-wavenumber arrays of each local space, using the center frequency of the excitation signal as the midpoint. The weighted average wavenumber of each frequency point within the selected frequency range is calculated using the amplitude corresponding to the wavenumber sequence at each frequency point as the weight. The mean of the sum of the weighted average wavenumbers at each frequency point is then used as the wavenumber corresponding to the center position of each local signal space, and these values ​​are sequentially spliced ​​to obtain the wavenumber curve of the guided wave signal. This method solves the problem in existing technologies where the obtained guided wavenumbers cannot accurately reflect the thickness changes of variable thickness structures.

This application provides a method and system for locating low-frequency broadband pulse signals under unknown environmental information. The method includes: obtaining the broadband wavenumber spectrum of the pulse signal using a hypothetical dedispersion formula; obtaining preliminary estimates of each mode using a variational Bayesian method; searching for optimal waveguide invariants and reference sound velocities; re-estimating each mode; and finally, substituting the wavenumber and phase information of each mode into a distance estimation cost function to estimate the distance to the pulse source. The advantages of this application are: by using the dedispersion formula and the variational Bayesian method, mode separation of broadband pulse signals can be achieved even with a short horizontal array aperture; and the phase difference between different modes can be used to estimate the source distance. Through this method, the optimal waveguide invariants and reference sound velocities can be searched under conditions lacking environmental information, reducing the error in source distance estimation.

This invention provides a method and system for three-dimensional high-frequency controllable source electromagnetic numerical simulation with dual-source excitation. The method constructs a single-source electromagnetic field grid model and a three-dimensional spatial domain total field equation, converting it into a quadratic field control equation by separating the primary and secondary fields. Fourier transform is used to transform the equations to the wavenumber domain, and shape function interpolation is performed iteratively to obtain the wavenumber domain numerical solution. A single-source forward excitation solution is obtained through inverse Fourier transform. A single-source reverse excitation solution is obtained by reversing the current direction. Finally, the forward and reverse solutions are vector-superimposed to obtain the dual-source excitation simulation result. This invention solves the technical problems of existing technologies, such as simulation distortion caused by neglecting displacement current in the 100kHz-10MHz frequency band, numerical calculation interference from field source singularities, and low spatial resolution of complex underground anomalies under single-source excitation. By simulating gradient field response characteristics through dual-source reverse superposition, the sensitivity and exploration resolution of underground target boundaries are significantly improved.

This invention proposes a wavenumber spectrum reconstruction and rapid fusion imaging method and system for arbitrary bistatic SAR. It proposes a method to consistently center the wavenumber spectrum of the spatial domain signal of the imaging scene, introduces a two-dimensional wavenumber spectrum position correction filter to compress the wavenumber spectrum width of the imaging scene, reduces the Nyquist sampling requirement in the spatial domain, and achieves accurate SAR imaging of the imaging scene with less computation, thus improving the imaging efficiency of the imaging method. Furthermore, while achieving accurate and consistent centering of the wavenumber spectrum of the imaging scene, this invention proposes a new method for calculating the minimum Nyquist sampling requirement of the spatial domain signal of the imaging scene. Based on the framework of the time-domain FFBP imaging method, this invention enables the imaging method to have good parallelism, utilizing parallel processing mechanisms on hardware platforms such as GPUs and FPGAs, which will further significantly improve the imaging efficiency of the time-domain FFBP imaging method in bistatic SAR systems in practical applications.

This application provides a wavefield decomposition method, apparatus, device, and medium based on wavefront phase direction, belonging to the field of geophysical exploration technology. The method includes: determining a wavefield decomposition operator based on the original wavefield and Thomsen parameters; the wavefield decomposition operator is a first-order pseudo-Helmholtz decomposition operator based on the wavefront phase direction; determining the wavenumber domain wavefield obtained after transforming the original wavefield to the wavenumber domain; performing computational processing based on the wavenumber domain wavefield and wavenumber, followed by inverse Fourier transform to obtain multiple intermediate quantities constituting an auxiliary wavefield; determining the auxiliary wavefield based on the multiple intermediate quantities and Thomsen parameters through an auxiliary wavefield expression; and performing wavefield decomposition based on anisotropic wavefield decomposition formula to achieve P-wave and S-wave separation, obtaining the P-wave and S-wave wavefields. This method not only achieves P-wave and S-wave vector wavefield separation and reduces imaging crosstalk noise, but also reduces computational load, balancing wavefield decomposition effect and computational efficiency.

This invention discloses a method for inverting the effective elastic thickness of the lithosphere based on intelligent truncation and inflection point matching, applied to a processor. The method includes the following steps: reading gridded topographic data and Bouguer gravity data stored on a hard disk or in memory to obtain the observation curve of coherence as a function of wavenumber; obtaining the monotonically decreasing coherence spectrum after truncation; solving for the logarithmic wavenumber corresponding to the coherence value at a preset value, denoted as the observed inflection point logarithmic wavenumber; establishing a mapping relationship between the theoretical inflection point logarithmic wavenumber and the effective elastic thickness; obtaining the effective elastic thickness of the lithosphere at the target grid point; traversing all grid points within the study area to generate a full-grid effective elastic thickness distribution array, thus obtaining the inversion result of the effective elastic thickness of the lithosphere. This invention significantly improves computational efficiency, achieves robust noise suppression while preserving the effective signal, and exhibits strong noise robustness.

This invention belongs to the field of imaging analysis technology and discloses a rapid detection method for illegal food additives based on Raman imaging. The method includes: at the start of the detection task, performing sparse Raman imaging scanning on the boundary of the target region of the sample to be tested to obtain a target pixel spectrum set; constructing a reference spectrum set, and generating a detection wavenumber interval by analyzing the stability changes of the wavenumber highlight ratio in the reference spectrum set and the spatial thermal variation characteristics of different wavenumbers in the sample to be tested; obtaining an evidence heatmap by analyzing the similarity of the detection intensity of candidate gratings in the reference spectrum set and the target pixel spectrum set within the detection wavenumber interval; continuously updating the target pixel spectrum set by analyzing the correlation between the change attributes of evidence gain and the growth of connected regions in the evidence heatmap; and outputting suspicious regions by analyzing the convergence change attributes of the evidence coverage heat increment and the stability characteristics of the region to be matched. This invention generates spatial evidence and location results for suspicious regions more quickly.

The application provides an array performance quantification analysis method and system for sea wave direction spectrum estimation, and relates to the technical field of array performance quantification analysis. The method comprises the following steps: determining the analytical upper limit of the array through wave number spectrum window calculation; determining the information utilization rate of the array by comparing the equivalent measurement point number and the real measurement point number of the array; obtaining the wave number sidelobe level by calculating the ratio of the maximum sidelobe peak value to the main lobe peak value in the wave number spectrum window, and then determining the energy leakage level of the array; determining the observation ability of the array by calculating the normalized average nearest neighbor distance between each measurement point of the array; obtaining the main lobe concentration degree by calculating the angle deviation between the direction of the vector and the direction of the center line of the correlation matrix of the array, and then determining the advantages and disadvantages of the main lobe shape of the array; and comprehensively evaluating the quantitative evaluation results of the above five dimensions to form the quantitative evaluation of the comprehensive performance of the array. The application is suitable for arrays with any measurement point number, and the performance pre-evaluation can be completed before the array is deployed.

The application discloses a dynamic sweep frequency range compensation method of an optical frequency domain reflectometry system, comprising the following steps: reading an actual beat frequency sequence of a main interferometer and an auxiliary interferometer, wherein the actual beat frequency sequence is obtained by primary sampling of an actual beat frequency sequence of the main interferometer and the auxiliary interferometer under a preset sweep frequency range, and the preset sweep frequency range is greater than a theoretical sweep frequency range required by the optical frequency domain reflectometry system under a target application scenario; determining a mapping relationship between time and wave number according to the actual beat frequency sequence of the auxiliary interferometer; mapping a resampling wave number sequence with equal wave number intervals to a time domain according to the mapping relationship between time and wave number, to obtain a resampling time sequence, wherein the resampling wave number sequence is constructed according to the theoretical sweep frequency range; and resampling the actual beat frequency sequence of the main interferometer according to the resampling time sequence, to obtain a theoretical beat frequency sequence of the main interferometer under the theoretical sweep frequency range. The dynamic sweep frequency range compensation method can adapt to the dynamic change of the sweep frequency range for compensation. The application further discloses an optical frequency domain reflectometry system and a demodulation method based on the above dynamic sweep frequency range compensation method.

This invention relates to the field of micro-motion surface wave exploration methods, and discloses an automatic extraction method for dispersion curves of micro-motion surface waves based on connected component analysis. The method includes cross-correlation extraction of virtual source surface wave shot gathers, frequency-wavenumber domain amplitude spectrum calculation, adaptive threshold binarization, connected component analysis, frequency-wavenumber domain surface wave mask generation, mask-amplitude matrix element multiplication, phase velocity picking, Hampel filtering, and automatic generation of dispersion curves. This invention utilizes image connected component analysis and other operations to process the amplitude spectrum of micro-motion surface waves, separating the surface wave signal region from the frequency-wavenumber domain amplitude spectrum image. It automatically identifies discrete phase velocity points from images containing only surface wave dispersion energy stripes and uses Hampel filtering to remove distortion points, ultimately achieving high-precision automated measurement of the dispersion curve.

This invention proposes a high-precision method for measuring airflow thrust by extracting the Doppler frequency shift difference from the scanning absorption spectrum. A tunable laser performs forward and reverse scanning of the absorption spectrum. The laser wavenumber scanning waveform is symmetrical about the lowest wavenumber point. The laser beam is split into two beams, which cross the longitudinal section of the airflow center. The target gas absorption spectrum curve is obtained by measuring the laser intensity curve. The sum of the central wavenumbers of the absorption spectrum in both forward and reverse scans along the airflow path is calculated, as is the sum of the central wavenumbers in both forward and reverse scans against the airflow path. The Doppler frequency shift difference is extracted from the difference between the two sums of central wavenumbers, thus measuring the airflow velocity. The static temperature of the airflow is obtained using colorimetric thermometry, and the static pressure of the airflow is obtained using a nonlinear fitting method. The thrust is calculated by combining the airflow velocity, static temperature, and static pressure. This invention achieves airflow velocity measurement resistant to temporal noise interference and has significant application prospects in the field of integrated space-ground thrust measurement for engines.

The application provides a point spread function fast spatial convolution method, which comprises the following steps: step 1, calculating an imaging profile and a point spread function field; step 2, determining the spatial position coordinates of the center position of the point spread function by circulation; step 3, determining an interpolation method and calculating the interpolation coefficients of the local imaging profile which contributes to the point spread function; step 4, performing wave number domain fast spatial convolution; step 5, multiplying the profile by the corresponding interpolation coefficients after filtering; and step 6, accumulating the filtering results of the local imaging profile to obtain a final filtered profile. The point spread function fast spatial convolution method can greatly improve the calculation efficiency of the point spread function spatial convolution filtering process and reduce the calculation cost based on the linear accumulation characteristics of the interpolation method.

The application provides a measurement method for reconstructing time-varying absorption based on fixed-point wavelength modulation technology, which comprises the following steps: applying a high-frequency sinusoidal scanning signal to a laser, wherein the scanning frequency is f m ; the wave number response of the laser has a nonlinear relationship with the current, and the nonlinear fitting of discrete wave numbers obtains a continuously changing wave number function v(t); the Beer-Lambert law is used to express the absorption rate α v (t) of the laser by the absorption medium; the Fourier transform and the lock-in filtering extraction are performed on α v (t) to extract the harmonic waves of the absorption rate function with time; the wave number information of the dynamic harmonic waves at any time is supplemented by numerically solving the inverse function of the wave number function at the rising edge or the falling edge, so that the absorption rate at each time is reconstructed, and the calibration-free measurement is realized. The absorption rate reconstructed by the application has a higher signal-to-noise ratio and does not reduce the time resolution of the spectrum.

The present application relates to the technical field of thickness measurement, and discloses a linear dimensional measurement method for AR module thickness, comprising: obtaining a spectral interference signal and resampling to a wave number space to generate a wave number domain complex sequence; extracting a real part, an imaginary part and a first derivative term of the wave number domain complex sequence; establishing an orthogonal component set; extracting a transient phase slope by using differential mapping between the orthogonal components; determining a wave number domain group delay distribution; calling a dispersion calibration matrix to correct nonlinear deviation; converting nonlinear phase evolution into linear phase gradient; fitting the linear phase gradient to solve a physical thickness value; and bypassing arctangent calculation and phase unwrapping by establishing phase gradient mapping logic, suppressing phase jump caused by interference envelope aliasing from the dimension of physical energy distribution, improving thickness calculation stability of an extremely thin medium layer under environmental interference, and realizing physical decoupling of material dispersion characteristics and geometric dimensional parameters.

The invention relates to a shallow sea equivalent earth sound model inversion method based on sparse Bayesian learning dispersion curve estimation, and the method comprises the following steps: 1, carrying out the time-frequency transformation of broadband sound source data received by a shallow sea vertical array, and obtaining multi-frequency-point and multi-snapshot frequency domain vertical array data; step 2, constructing a horizontal wavenumber hypothesis interval and a modulus depth function hypothesis space corresponding to each frequency point according to a water layer sound velocity profile and environmental prior information; and step 3, based on a normal mode sound propagation theory, frequency domain vertical array data of each frequency point is modeled as a weighted sum of each mode depth function in the mode depth function hypothesis space, and a weight vector is a horizontal wave number spectrum. According to the method, the sound field intrinsic characteristic, namely the dispersion curve, irrelevant to the sound source is directly extracted from the vertical array data, and an equivalent earth sound model concept is utilized, so that an earth sound parameter inversion scheme which is more stable, is more tolerant to model mismatch and can effectively avoid attenuation coefficient coupling influence is realized.

To provide a structural component with a highly durable protective film against plasma. [Solution] The structural member 10 comprises a base material 100 and a protective film 200 covering the surface 110 of the base material 100. The protective film 200 mainly contains yttria, and in the Raman spectrum of the protective film 200 obtained by Raman spectroscopy, 370 cm⁻¹ -1 The half-width of the peak at nearby wavenumbers is 23 cm. -1 That's all.

The application discloses a hybrid domain intelligent seismic data processing method for old two-dimensional seismic data reprocessing, and relates to the technical field of oil exploration, evaluation and development. The method comprises the following steps: extracting the structural features of the preprocessed seismic data in the time-space domain, and obtaining the local structural direction of the seismic reflection based on the structural features; constructing a structure-noise coupling state quantity based on the local structural direction; performing state-driven structure-oriented update processing on the preprocessed seismic data in the structural domain according to the structure-noise coupling state quantity, so as to obtain the updated seismic data in the structural domain; introducing the structural dip angle information of the structural domain into the frequency-wavenumber domain, and performing structure-restricted frequency-wavenumber domain suppression processing on the updated seismic data in the structural domain, so as to obtain the target seismic data processed in the hybrid domain; and solving the problems that the structure-oriented filtering and the frequency-wavenumber domain filtering are independent of each other, the parameters are static, and the processing stability is insufficient in the prior art.

The application provides a longitudinal and transverse wave separation water exploration method and system based on a reflection coefficient and a stress gradient, and the method comprises the following steps: collecting original seismic record data of a tunnel site and performing pretreatment; a longitudinal and transverse wave separation method is used to separate longitudinal waves and transverse waves from the pretreated seismic wave data; wherein, F-K filtering separates wave fields with different apparent velocities through frequency-wavenumber domain transformation, and realizes preliminary separation of longitudinal waves and transverse waves; for the overlapping part of the longitudinal waves and the transverse waves remaining in the F-K domain; linear Radon transformation is used to map the data from the time-space domain to the ray parameter domain, and further separate the wave fields with similar apparent velocities; a polarization filter is used to finally separate the longitudinal waves and the transverse waves by using the polarization characteristics; based on the separated longitudinal waves and the transverse waves, reflection coefficient imaging and stress gradient imaging are calculated respectively; and according to the reflection coefficient imaging result and the stress gradient imaging result, the underground water occurrence condition is identified. The identification precision of the underground water occurrence condition is improved.

This invention discloses a phase correction method for a GPU-accelerated swept-frequency OCT imaging system, belonging to the field of signal processing technology. The method constructs an SS-OCT system and acquires MZI reference signals and OCT interferometric signals; it locally upsamples the MZI signals, calculates the sub-pixel shift of each column of signals through threshold detection and reduction operations; it uses frequency-domain phase compensation to correct the nonlinear error of the OCT signal; and it achieves wavenumber domain resampling based on the Hilbert transform of the reference columns. This invention employs CUDA parallel computing to optimize the upsampling, frequency-domain shift, and phase unwrapping processes, and combines local computation strategies to reduce redundant operations, significantly reducing the processing time per frame and increasing the scanning rate to 2.48 times that of traditional methods. This improvement is significant and can meet the data processing requirements of higher-speed SS-OCT.

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.

This invention discloses a method and system for extracting vehicle signals based on distributed acoustic sensing, comprising: acquiring raw spatiotemporal vibration signals collected along a road by a distributed fiber optic acoustic sensing system; performing bandpass filtering on the raw spatiotemporal vibration signals to obtain a preliminary filtered signal; superimposing the preliminary filtered signals in the time dimension within a preset time window to obtain a signal-enhanced superimposed signal; normalizing the signal amplitude of each sensing channel in the superimposed signal to obtain a normalized vibration signal; transforming the normalized vibration signal to the frequency-wavenumber domain; and applying a hard threshold filter to the frequency-wavenumber domain signal to remove irregular noise to obtain a first filtered signal. The method and system of this application improve the accuracy and robustness of extracting vehicle signals from complex road noise backgrounds.

This invention relates to the field of ground-penetrating radar (GPR) detection technology, and particularly to a method for constructing an initial model for GPR imaging. The method includes: acquiring GPR data and preprocessing it; performing frequency-wavenumber domain migration imaging under multi-velocity scanning to obtain migration imaging results at different velocities; constructing a two-dimensional focusing evaluation index system to evaluate all migration imaging results and obtain the optimal velocity and optimal focusing imaging result; extracting subsurface medium structural features based on the optimal focusing imaging result, and constructing an initial GPR imaging model by combining the physical mapping relationship between electromagnetic wave velocity and relative permittivity. This invention solves the technical problems of traditional initial model construction relying on human experience, insufficient prior information, and low matching degree between the model and the actual subsurface structure. The final output initial model can be directly used as input for subsequent GPR imaging or inversion algorithms, effectively improving the focusing of subsequent imaging and the stability and reliability of inversion results.

The application discloses an industrial pipeline flow velocity measurement method based on a differential array and an MVDR algorithm, wherein step 1 is that fluid flow signals in a pipeline are collected through a multi-sensor array distributed on the outer wall of the pipeline, and adjacent channel differential preprocessing is carried out to suppress common-mode noise; step 2 is that a frequency domain signal is constructed by using STFT, a time recursive smoothing mechanism is adopted to update a covariance matrix, and dynamic adaptability is enhanced; step 3 is that an improved MVDR algorithm is used to calculate a wave number-frequency (k-f) spectrum diagram in combination with adaptive diagonal loading and SVD regularization technology; step 4 is that background noise suppression and energy enhancement processing are carried out on the k-f two-dimensional power spectrum diagram, and effective turbulent flow characteristics are highlighted; and step 5 is that high-precision real-time measurement of fluid flow velocity is realized through a tilt superposition method in combination with a spline interpolation fine search strategy. The application effectively solves the problems of inaccurate covariance matrix estimation and difficult feature extraction under low signal-to-noise ratio in complex working conditions.

This application proposes a near-field three-dimensional imaging method for sparse MIMO arrays based on efficient spectrum reconstruction. The method includes: establishing a two-dimensional MIMO array imaging model, assuming that the receiving antennas of the two-dimensional MIMO array are fully arranged, and analyzing the imaging process of a single transmitter; further assuming that the receiving antennas of the two-dimensional MIMO array are sparsely arranged along the X-axis, and determining the actual recoverable spatial scattering signal based on the imaging process of a single transmitter; performing a Fourier transform on the actual recoverable spatial scattering signal first along the Y-axis and then along the X-axis to obtain a uniform wavenumber spectrum; performing a two-dimensional inverse Fourier transform on the uniform wavenumber spectrum to obtain the target spatial scattering signal, and then converting it to the frequency domain; extracting the component corresponding to the frequency of the target distance in the frequency domain, and performing phase compensation to recover the sub-image corresponding to a single transmitter; and finally accumulating the sub-images corresponding to all transmitters to obtain a complete three-dimensional imaging result.

This invention relates to a damage imaging method for variable-thickness thin-walled structures based on 2D-CWT local wavenumber analysis, belonging to the field of nondestructive testing technology. The method involves exciting the test object at a preset excitation point on the variable-thickness thin-walled structure to generate guided wave signals. The guided wave signals on the test object surface are sampled to obtain a three-dimensional wavefield signal. This signal is then subjected to a three-dimensional Fourier transform, and the wavenumber-amplitude array corresponding to the center frequency is extracted. After filtering, the A0 mode signal, which better reflects structural changes, is retained. After conversion back to the spatial domain, multiple wavelet transforms are performed to extract multiple wavelet coefficient spectra. Finally, the multiple wavelet coefficient spectra are superimposed to obtain a damage image that reflects the distribution and changes in damage location. Compared with existing technologies, this embodiment not only simplifies the detection process but also solves the problems of effectiveness and accuracy in signal processing and the difficulty in imaging damage in variable-thickness thin-walled structures.

The application provides an X-band radar significant wave height inversion method based on Bayesian optimization and an adaptive threshold, comprising the following steps: acquiring an X-band radar image and preprocessing; defining a parameter space of a local window size and a false alarm probability, constructing a multi-dimensional shadow quality score function as an optimization objective function, and performing Bayesian iteration optimization to select an optimal parameter combination; calculating a threshold value of each pixel point through a local dynamic threshold value formula, generating a binary shadow mask based on the threshold value of each pixel point, and calculating an optimal shadow rate of the whole image; performing wave number spectrum analysis on the preprocessed X-band radar image, screening effective wave numbers through a wave number spectrum mask, calculating a sea wave root mean square wave steepness based on the optimal shadow rate, and combining the zero-crossing period to calculate the significant wave height. The method realizes high-precision and adaptive significant wave height inversion without the support of buoys.

This invention provides a target depth discrimination method based on wavenumber difference domain feature extraction of a horizontal array of negative-gradient waveguides, belonging to the field of target depth discrimination technology. This invention uses a horizontal linear array deployed on the seabed to receive broadband acoustic pressure signals from shallow-sea negative-gradient waveguides. After performing Fourier transform on the received signal, wavenumber domain beamforming is performed in the frequency domain to obtain the beam output. The beam output is scanned on the horizontal wavenumber domain to obtain the wavenumber spectrum. A two-dimensional distribution matrix of horizontal wavenumber difference versus frequency is obtained through coordinate transformation, and a two-layer game model is used to optimize the sampling accuracy. Energy accumulation is performed along the full bandwidth of the signal at each sampling point in the horizontal wavenumber difference domain to construct a cumulative energy versus horizontal wavenumber difference curve. The coordinates corresponding to the peak value of the cumulative energy versus horizontal wavenumber difference curve are calculated and compared with the criteria to complete the depth discrimination, thus solving the technical problem of insufficient accuracy in sound source depth discrimination in shallow-sea negative-gradient waveguides.