307 results about "Frequency wave" patented technology

The invention provides a frequency converter dynamic fault diagnosis method and system based on a multi-brand load test platform. According to the method, multiple real-time operation parameter sets are acquired, the amplitude attenuation threshold and the frequency fluctuation interval of a voltage waveform fragment are dynamically adjusted according to a load mode configuration file, the dynamic voltage reference parameter corresponding to the current load mode is generated, and then the actual waveform and an expected current phase curve are compared frame by frame; the method comprises the following steps: firstly, calculating to obtain a phase offset, then constructing a multi-dimensional operation characteristic spectrum, then carrying out time sequence cross validation on a sudden change time node of a power factor jump trajectory and an abnormal waveform position in a harmonic distortion incidence matrix, outputting an abnormal mode code, and finally, matching a load adaptation grade constraint condition to generate a diagnosis report; according to the technical scheme provided by the invention, the fault diagnosis precision and the cross-brand system adaptation capability in a complex load scene are remarkably improved, and the problem of misjudgment of a single brand threshold rule in a multi-device scene is effectively solved.

The invention relates to a time-varying power high-precision calculation technology of an electric drive system under strong electromagnetic noise interference, and mainly solves the problem of inaccurate power calculation of the electric drive system under strong electromagnetic environment noise and frequency time-varying fluctuation scenes. According to the core technology, a dominant frequency fluctuation curve of a signal is obtained through dynamic tracking of a dominant frequency, and a dynamic band-pass filter changing along with the dominant frequency of the electric drive system is constructed; suppressing pulse noise by combining amplitude self-adaptive filtering of a nonlinear weighting function; a phase demodulation technology fusing zero crossing point correction and Hilbert transform is adopted to eliminate the phase interference problem caused by complex waveforms and weak noise signals; and finally, establishing a time-varying power physical model based on the sliding window. According to the technology, the power calculation accuracy of the electric driving system under the conditions of strong field environmental noise and continuous main frequency conversion is remarkably improved.

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 discloses a broadband wave-absorbing material based on an MAX-phase metasurface structure and an impedance matching optimization method of the broadband wave-absorbing material. The wave-absorbing material comprises an MAX-phase ceramic substrate and periodic metasurface structures which are arranged on the surface of the MAX-phase ceramic substrate in an array mode and composed of conductive resonance units. The resonance units are isolated through gaps, an equivalent R1L1C1 series resonance circuit is formed in an electromagnetic field, and a base body is equivalent to a parallel resistor R2. By establishing an equivalent circuit model and optimizing parameters R1, L1, C1 and R2, impedance matching of the wave-absorbing material in a target frequency band can be regulated and controlled, so that the wave-absorbing material at least has an absorption peak of which the reflection loss is less than-10 dB. According to the optimization method, electromagnetic simulation and circuit simulation are combined, optimized circuit parameters are reversely mapped into structure geometric parameters, material preparation is guided, and accurate design and broadband absorption of the wave absorbing performance are achieved.

The invention discloses a low ionosphere intelligent inversion method based on VLF radio wave detection, and the method comprises the steps: collecting ground-based very-low-frequency wave amplitude data, defining a gated cycle unit network objective function as an optimized performance index, and employing a mean square error as the objective function; and carrying out dynamic position updating by adopting a whale optimization algorithm, setting a double-stop criterion, and stopping iterative training to obtain an optimal model when the maximum number of iterations or a verification error convergence threshold value is reached. The calculation result of the LWPC model is used as a training set, the GRU network is used as an objective function estimator from foundation very low frequency data to low ionosphere parameters, the inversion method can accurately approach a real model, and the algorithm performance is effective and feasible and is remarkably improved compared with an existing model.

The invention belongs to the technical field of comprehensive utilization of ocean renewable energy sources, and particularly relates to a pilot frequency coupling-based wind wave energy multi-degree-of-freedom broadband control method, which comprises the following steps of: performing frequency domain identification on wind wave environment characteristics, and constructing a wind wave pilot frequency energy coupling model; based on the motion response characteristics of the multi-degree-of-freedom floating platform, designing a pilot frequency energy regulation and conversion mechanism; a full-working-condition dynamic optimization control strategy is adopted, and cooperative operation and energy flow self-adaptive distribution of the wind energy conversion unit and the wave energy conversion unit are achieved. Aiming at the significant difference and relevance of wind energy and wave energy in frequency characteristics, time scale and spatial distribution, a pilot frequency wind wave coupling dynamic model is established, and broadband capture of low-frequency wind-induced and high-frequency wave-induced coupling energy is realized under complex sea conditions through multi-degree-of-freedom motion decoupling and state observation, so that the wind-induced and high-frequency wave-induced coupling energy is obtained. The energy utilization rate, the attitude stability and the structural safety of the system are effectively improved, and good robustness and engineering adaptability are achieved.

To ensure the power supply adjustment capability to respond appropriately on a node-by-node basis to frequency fluctuations on a node-by-node basis.SOLUTION: A power system adjustment power management system 100 includes a frequency fluctuation index calculation unit 102 that calculates a frequency fluctuation index that represents a frequency fluctuation within a predetermined time at a point connected to each generator in the power system in response to a fault disturbance, a frequency fluctuation index constraint determination unit 103 that compares the frequency fluctuation index of the power system with a threshold value and determines whether the frequency fluctuation index is within an appropriate range or not, and an output response amount increment calculation unit 104 that calculates a change sensitivity of the frequency fluctuation index to an output response amount when the frequency fluctuation index is not within the appropriate range, and calculates an increment in the output response amount at the point on the basis of the change sensitivity of the calculated frequency fluctuation index.SELECTED DRAWING: Figure 2

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 provides a TMD lockout control method for motion suppression of a semi-submersible platform, and the method comprises the steps: carrying out the frequency domain decomposition of a random wave predicted by a target sea condition, obtaining the energy distribution of each frequency component, obtaining the equivalent amplitude of each frequency component according to the energy distribution, considering the amplitude response of the platform under the action of waves of different frequencies, and achieving the motion suppression of the semi-submersible platform. The method comprises the following steps of: calculating a weight ratio of platform motion response caused by each frequency component under the action of random waves by integrating three types of information, namely amplitude, amplitude response and motion suppression effect, and finally carrying out weighted combination on the locking time corresponding to each frequency component according to the weight ratio, so as to obtain the motion suppression effect of the platform. And the optimal locking control time suitable for the current random wave is obtained. According to the method, a high-complexity non-causal control command does not need to be deduced, control parameters can be updated in real time according to short-term sea condition changes, pitching response of a platform is effectively reduced, and comprehensive optimization control over multi-frequency waves is achieved.

The present invention relates to a tip for a high-frequency skin care device, the tip comprising: a housing; a first substrate which is disposed inside the housing; at least one electrode which is disposed on the first substrate and applies high-frequency waves to the skin; a second substrate which is disposed opposite the first substrate inside the housing in order to supply power to the first substrate; and a connector which electrically connects the first substrate and the second substrate, wherein the connector has a length which is longer than the distance between the first substrate and the second substrate.

The invention discloses a magnetic suspension bearing displacement detection method and device, a magnetic suspension bearing system, a storage medium and a computer program product, an axial displacement detection area of a magnetic suspension bearing is provided with four displacement detection probes used for detecting axial displacement of a rotor, and the four probes are divided into two groups; the first group of two probes are installed along a first symmetrical direction, the second group of two probes are installed along a second symmetrical direction orthogonal to the first symmetrical direction, the design parameters of the same group of probes are consistent, and the design parameters of the different groups of probes are not consistent; the method comprises the following steps: carrying out mean value and difference operation on signals acquired by four probes to eliminate radial coupling interference; and filtering the signal subjected to mean value operation and differential operation by adopting same-frequency notch processing so as to filter radial coupling interference. According to the scheme, high-precision stable operation of magnetic suspension axial displacement is realized.

The invention discloses a shield segment support crack disease impact elastic wave detection method and device based on KNN-BiLSTM. The detection method specifically utilizes impact elastic wave equipment to test a shield segment support, collects the frequency, wave velocity, amplitude, frequency and curve change characteristics of Rayleigh waves propagated from the surface of a structure, and uses a network structure based on KNN-BidirectionalLSTM to carry out data processing on a multi-element elastic wave characteristic and lining disease characteristic mapping model. And obtaining the shield segment support crack depth and water permeability detection result at the detection position. According to the method, the accuracy of crack depth detection is remarkably improved, the over-fitting phenomenon is effectively relieved, the recognition accuracy and speed of the model are improved, meanwhile, the crack depth prediction result can be obtained, the crack water permeability type can be detected, and the method has important practical value and popularization significance.

The invention provides hot-melt wave-absorbing resin, a low-frequency wave-absorbing prepreg and application of the hot-melt wave-absorbing resin and the low-frequency wave-absorbing prepreg in a low-broadband magnetic wave-absorbing composite material. The hot-melt wave-absorbing resin is prepared from the following raw materials: hot-melt resin and a composite absorbent, the composition comprises a combination of a coupling agent modified conductive absorbent and a magnetic absorbent. The raw materials of the low-frequency wave-absorbing prepreg comprise the hot-melt wave-absorbing resin and reinforced fibers with low dielectric constant and low gram weight. The hot-melt wave-absorbing resin provided by the invention realizes the low-frequency wave-absorbing performance covering 1GHz. Through the synergistic effect of the conductive absorbent and the magnetic absorbent, the broadband wave-absorbing prepreg covering low frequency is prepared by using a hot melting method, the dielectric loss of the wave-absorbing prepreg is improved, and the low-frequency wave-absorbing performance is enhanced. And the formula can be changed according to frequency band requirements to meet the wave absorbing requirements of different frequency bands (from 0.3 GHz to 18GHz). According to the low-broadband magnetic wave-absorbing composite material with the wave-absorbing honeycomb provided by the invention, the wave-absorbing bandwidth coverage is expanded by 1-18 GHz.

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 L-band wave-absorbing material and a preparation method thereof, the wave-absorbing material comprises a Fe-Si-Al composite material, and the composite material is Fe-Si-Al soft magnetic particles with oxide layers formed on the surfaces; wherein the content of each element in the raw materials of the Fe-Si-Al soft magnetic particles is as follows: 84.5 to 85.5 weight percent of Fe, 9.5 to 10 weight percent of Si and 5 to 5.5 weight percent of Al; the diameter-thickness ratio of the Fe-Si-Al soft magnetic particle raw material is 50-100, and the average diameter of the Fe-Si-Al soft magnetic particle raw material is 20-40 [mu] m; and the thickness of the oxide layer is 5-12 nm. The wave-absorbing material disclosed by the invention has excellent low-frequency wave-absorbing performance and has the characteristics of being thin, light, wide and strong; the impedance matching Z of the wave-absorbing material is larger than or equal to 4, the minimum reflectivity of a product with the thickness being 5 mm is smaller than-10 dB within 1-2 GHz, and the wave-absorbing material can be suitable for being used under multiple wavelengths of the L wave band and meets the use requirement of the wave-absorbing material.

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.

The invention provides a temperature-resistant radar infrared compatible stealth coating and a preparation method thereof. The problems that an existing radar infrared compatible stealth coating is insufficient in temperature resistance and poor in low-frequency wave absorbing performance are solved. The temperature-resistant radar and infrared compatible stealth coating sequentially comprises a bonding layer, a wave absorbing layer and an infrared stealth layer from bottom to top, the bonding layer is made of NiCrAlY or NiCoCrAlY, and the bonding layer is made of NiCoCrAlY; the material of the wave absorbing layer is 20 wt%-65 wt% of a ceramic matrix and 80 wt%-35 wt% of an absorbent; the chemical formula of the absorbent is Fe0. 7Al0. 3Ti (1-x) RxO3, in the formula, x is equal to 0.2-0.55, and R is Ni, Nb or Ta; the infrared stealth layer is a precious metal layer arranged in a periodic structure.

The invention relates to the technical field of crossing of geophysical exploration and artificial intelligence, and discloses a three-dimensional VSP data reconstruction method based on a three-dimensional blind sidewalk time frequency-space multi-domain interpolation network model, and the method comprises the steps: obtaining a to-be-reconstructed three-dimensional VSP data volume containing an irregular missing sidewalk; inputting the three-dimensional VSP data volume into a trained three-dimensional space-time-frequency mixed domain convolutional network model; performing down-sampling on the input data through an encoder to extract initial spatial-temporal characteristics; inputting the initial spatiotemporal features into a residual spatiotemporal-frequency wavenumber domain joint convolution feature fusion module to obtain fusion features; and inputting the fusion features into a decoder, and reconstructing a complete three-dimensional VSP data volume through up-sampling operation. According to the invention, through joint learning of ground seismic data (providing a macrostructure) and illuminance data (providing a physical propagation path), a reconstruction result with a reasonable geologic structure and extremely high fidelity of wave field features can be generated.

The invention provides a method, device and equipment for exciting a single-mode guided wave in grounding flat steel, and belongs to the technical field of engineering structure detection, and the method comprises the steps: building a two-dimensional section model of the detected grounding flat steel through finite element analysis software, defining boundary conditions for the width and thickness in the two-dimensional section model, and carrying out the mode analysis and solving of the grounding flat steel. Performing statistics to obtain frequency-wave number data; based on frequency-wave number data, a phase velocity frequency dispersion curve and a group velocity frequency dispersion curve are drawn, after a corresponding mode is selected, excitation of specific single-mode guided waves is achieved in combination with a wave structure diagram and the application size and direction of a modulation load, and due to the fact that a two-dimensional section model including a width condition is obtained through finite element analysis, the excitation accuracy of the guided waves is improved. The phase velocity frequency dispersion curve and the group velocity frequency dispersion curve are recalculated, the corresponding wave structure diagram is combined, and the appropriate modal guided wave under the specific frequency is reselected for single excitation, so that the appropriate modal can be more accurately selected, and the defect detection accuracy is improved.

The device for separating good and bad seeds using resonant frequencies includes several key components: a lifting unit(7) with a seed inlet, outlet, and bucket elevator to transport seeds vertically into an air tunnel(11); an air tunnel with an air blower to separate light waste from heavier seeds; a screening device(14) with holes to sort seeds based on size or shape; a divider(15) that disperses seeds using an air stream over a grooved shaft; a low-frequency wave transmitter that vibrates the seed collection; and a high-frequency wave transmitter with piezoelectric elements connected to a frequency generator and amplifier. The screening device is designed to separate seeds based on size, and the low-frequency transmitter uses a diaphragm to convert electrical signals into sound waves. The separation surface features at least two jacks for adjusting its slope, helping control the seed ejection path.

The invention discloses a small surveying and mapping blind area double-frequency synthetic aperture underwater acoustic imaging system and method, and the system comprises a double-frequency acoustic array, a multi-channel transmitting and receiving machine, a double-frequency synthetic aperture imaging signal processing module, a double-frequency image fusion imaging module, and a high-frequency acoustic array and a low-frequency acoustic array for synchronous transmission. The high-frequency acoustic array transmits and receives high-frequency chirp signals to detect a short-range to medium-range area of a target area, the low-frequency acoustic array transmits and receives low-frequency chirp signals to detect a medium-range to remote area of the target area, and the beam opening angle of the high-frequency acoustic array is larger than that of the low-frequency acoustic array; and an overlapping region exists between the detection regions of the high-frequency acoustic array and the low-frequency acoustic array. According to the invention, the dual-frequency wave beams emitted by the dual-frequency acoustic array are used for cooperative detection to cover a larger surveying and mapping range, and the structural parameter optimization of the acoustic array is combined, so that the blind area is controlled within the minimum range acceptable by engineering on the premise of ensuring the remote high resolution, and the balance between the detection efficiency and the technical feasibility is realized.

The invention relates to the technical field of seismic exploration, and provides a three-component seismic data vector anti-aliasing interpolation reconstruction method and device. The method comprises the following steps: representing three-component seismic data as a pure quaternion in a time domain, and carrying out vector combination; converting the pure quaternion data of the time-space domain into a frequency-space domain to obtain frequency-space domain data; converting the frequency-space domain data into a frequency-wave number domain; constructing a mask matrix in the frequency-wavenumber domain by using an inclination angle scanning strategy; performing vector anti-aliasing interpolation reconstruction based on the frequency-space domain data and the mask matrix to obtain a frequency-space domain reconstruction result; and inversely transforming the frequency-space domain reconstruction result to a time-space domain to obtain a time domain three-component three-dimensional data anti-aliasing reconstruction result. The method can effectively solve the problem of anti-aliasing reconstruction of three-component seismic data vectors containing irregular missing traces and regular missing traces, and can improve the accuracy of effective wave event identification.

The invention discloses an oil abrasive particle detection device based on pseudo-random signal excitation and an inversion method, a pseudo-random excitation module outputs pseudo-random alternating current excitation formed by combining a plurality of waveforms, and the pseudo-random waveforms are not less than three frequency waveforms; the sensing module is a three-coil balance type, double-coil mutual inductance type or single-coil self-inductance type inductance sensing unit, coils in the sensing module construct a detection area with an alternating magnetic field under the excitation of alternating current, and the alternating magnetic field has pseudo-random characteristics; the signal acquisition and fitting module detects an induced voltage signal of the coil, and signal pulses generated by the metal abrasive particles under different excitation waveforms are obtained through fitting according to pseudo-random alternating current excitation characteristics; and the abrasive particle feature inversion module performs inversion according to the abrasive particle pulse signals generated by fitting under each excitation, and calculates the equivalent radius, the conductivity and the magnetic conductivity corresponding to the abrasive particles, so as to determine the material and the size of the abrasive particles. According to the invention, the material, size and concentration information of the abrasive particles can be accurately obtained.

The invention belongs to the technical field of signal and information processing, relates to a modal time delay compensation continuous sound signal target depth estimation method based on a linear array, and is suitable for sonar signal processing. According to the method, on the basis of F-K transformation, through fitting of a sound velocity profile, compensation of modal time delay of each order of each array element, separation of modal of each order in an array receiving signal and a frequency-wavenumber domain, and design of a theoretical curve binary mask filter, modal energy of each order is extracted to be matched with a search depth; and depth estimation of a continuous sound signal target under a general sound velocity profile condition is realized. According to the invention, the depth estimation of a continuous sound signal target is realized, and the problems that a vertical array is difficult to maintain in engineering practice, modal aliasing exists in a continuous signal time-frequency domain by a single hydrophone, and the depth estimation precision error of a depth estimation method under a general sound velocity profile condition is large are solved.

The invention provides a frequency-wavenumber domain-based matrix array full-matrix capture three-dimensional ultrasonic imaging method and system, and belongs to the technical field of ultrasonic imaging. Five-dimensional time-space domain radio frequency data are collected through a two-dimensional full-sampling matrix array and are converted into a frequency-wave number domain through five-dimensional fast Fourier transform, angular frequency is mapped into axial wave number through Stolt interpolation, data resampling is achieved, then three-dimensional image frequency spectrum data are synthesized by defining spatial wave number coordinates of an image and conducting coherence stacking, and the image frequency spectrum data are obtained. And finally, reconstructing a high-quality three-dimensional ultrasonic image through three-dimensional inverse fast Fourier transform. Compared with a traditional delay summation beam forming method, the method has the advantages that the calculation efficiency is remarkably improved, the speed is increased by several times to dozens of times, the spatial resolution, the contrast noise ratio and the spot signal-to-noise ratio are remarkably improved, and the method is suitable for high-resolution real-time three-dimensional and four-dimensional ultrasonic imaging application.

The invention relates to the technical field of pipeline flow velocity measurement, and provides a non-contact pipeline fluid flow velocity measurement method based on a neural network model, and the method comprises the steps: collecting signal data sets at different pipeline flow velocities through a piezoelectric film sensor; performing two-dimensional Fourier transform on the signal data set, and converting the signal into a two-dimensional energy spectrogram of a frequency-wavenumber domain; the two-dimensional energy spectrogram predicts the flow velocity of the fluid through a two-dimensional neural network model. The collected signals are subjected to two-dimensional Fourier transform and converted into the two-dimensional energy spectrogram of the frequency-wavenumber domain, the signal processing capacity is effectively improved, more accurate and meaningful input data are provided for the two-dimensional neural network model, the two-dimensional neural network model is adopted for flow velocity prediction, the two-dimensional energy spectrogram serves as input, and the flow velocity prediction accuracy is improved. And features are automatically extracted and the flow velocity is predicted through a deep learning technology. According to the method, a traditional signal algorithm for processing the workpiece problem in the complex turbulence environment through the flow speed is overcome, and the measurement precision and robustness are improved.

The invention discloses a marine radar target detection algorithm and system based on a space-time joint filtering technology, and belongs to the technical field of marine remote sensing. In order to solve the problem of low target detection probability under strong sea clutter interference, three-stage processing is adopted: firstly, same-frequency interference suppression is performed on an original radar image sequence, polar coordinate echo data is converted to a frequency wavenumber domain through three-dimensional Fourier transform, and sea clutter energy in a frequency band [kx, ky] is filtered by using a dispersion relation filter; secondly, intercepting a central region of a specific wave number spectrum, extracting target energy meeting a linear equation by adopting a Hough straight line detection filter, and reconstructing a target enhanced image through three-dimensional inverse Fourier transform; and finally, performing target point fine detection on the processing sequence. According to the method, the strong sea clutter signal can be effectively suppressed and the target signal can be extracted only by using the echo amplitude information of the radar, so that the signal-to-noise ratio of the image is enhanced, the target detection probability under the strong sea clutter condition is further improved, and the method is suitable for all marine radars.

The invention discloses a metal internal defect rapid imaging detection method based on frequency domain interpolation and laser ultrasound, and belongs to the field of laser ultrasound nondestructive testing. The method comprises the following steps: firstly, carrying out large-interval rapid scanning on a local area of the surface of a tested piece by utilizing laser ultrasound, obtaining a group of ultrasonic body wave time domain signals with the number of x at different positions of the surface of a material, and then carrying out two-dimensional Fourier transform on the obtained time domain signals to obtain a frequency-wave number two-dimensional signal matrix; zero filling is carried out on a high-frequency part in the frequency domain, and then two-dimensional inverse Fourier transform is carried out to obtain interpolation to obtain a group of n time domain signal matrixes (n is gt; and finally, carrying out synthetic aperture imaging processing on the interpolated time domain signal to obtain a high-resolution synthetic aperture imaging result. According to the invention, for metal internal defect detection and imaging, the problems of long time consumption, large required data volume and the like of traditional laser ultrasonic synthetic aperture detection can be effectively solved, and the laser ultrasonic synthetic aperture detection efficiency and the imaging resolution are greatly improved.

The invention relates to a Lamb wave frequency dispersion characteristic sparse reconstruction method based on non-convex optimization, and belongs to the technical field of high-end equipment perception and test.The method comprises the steps that excitation is conducted on a U-shaped suspension arm, and time domain sampling signals at the junction of a U-shaped suspension arm structure are obtained; the time domain sampling signals are preprocessed; constructing a non-convex sparse frequency dispersion curve estimation model based on the preprocessed signal; and converting the non-convex sparse frequency dispersion curve estimation model into an optimization problem, searching a convex preserving condition of a target function, selecting a forward and backward splitting algorithm for solving, obtaining frequency-wave number distribution, and further extracting a frequency dispersion curve. The method solves the problems that a traditional convex regularization method is limited in induction sparse capability and underestimates signal amplitude. Through a non-convex optimization method, the purpose of accurate estimation of the frequency dispersion curve based on fewer measurement points is achieved.

The invention discloses an ultra-wideband honeycomb wave-absorbing structure and equipment with independently regulated electromagnetic loss. The structure comprises a supporting structure, a low-frequency magnetic wave-absorbing structure and a high-frequency electric resonance type wave-absorbing structure. Wherein the supporting structure is a main body structure of the ultra wide band honeycomb wave-absorbing structure with independently regulated electromagnetic loss, and is used for supporting and fixing the low-frequency magnetic wave-absorbing structure and the high-frequency electric resonance type wave-absorbing structure. The low-frequency magnetic wave-absorbing structure is used for absorbing electromagnetic waves of P and L wave bands, and the high-frequency electric resonance type wave-absorbing structure is used for absorbing electromagnetic waves of S to Ku wave bands. According to the structure, the advantages of different wave-absorbing mechanisms are comprehensively utilized, the advantages of broadband, low-frequency coverage and low reflectivity are considered under the low-profile performance, the independent regulation and control capacity of the low-frequency wave-absorbing structure and the high-frequency wave-absorbing structure is good, the high-frequency wave-absorbing structure can introduce different performances by flexibly designing different structures, and the flexibility is higher. The invention relates to the technical field of electromagnetic protection and radar stealth.