57 results about "Nonlinear coefficient" patented technology

The invention belongs to the technical field of nondestructive testing, and particularly relates to a detection method for quantitatively evaluating fatigue damage in a pipeline through a nonlinear ultrasonic technology. 316 stainless steel and SA335GRP-11 ferrite steel samples are adopted, a welding seam area is formed through V-shaped groove welding, fatigue loading is conducted, and actual pipeline fatigue damage is simulated; for the samples with different fatigue cycles, nonlinear response signals of the samples are obtained; fourier transform is carried out on the obtained signal to obtain an energy spectrum of the signal, and energy changes of the signal on a fundamental frequency band and a second harmonic frequency band are analyzed; and calculating a nonlinear coefficient, and analyzing a change rule of the nonlinear coefficient along with fatigue cycles, so that the evolution process of fatigue damage in the pipeline is evaluated. According to the method, energy is used for replacing the amplitude value, on the basis of the formula principle, integration is used for replacing the amplitude value to improve the intensity of the characterization nonlinear ultrasonic signal, the early stage of damage and the later stage of crack initiation are detected, and reliable guarantee is provided for safe operation of an industrial pipeline system.

The invention provides a comprehensive noise reduction performance evaluation method for a nonlinear ultrasonic detection signal noise reduction algorithm, and the method comprises the steps: firstly constructing a multi-working-condition noise reduction performance pre-screening mechanism based on error band analysis based on early-stage experimental data, and then introducing a radar map as an evaluation tool for the comprehensive noise reduction effect of the signal noise reduction algorithm. The noise reduction effects of a moving average method (MA), a spectral subtraction method (SS), a short-time Fourier transform method (STFT), a wavelet transform method (WT) and an orthogonal matching pursuit algorithm (OMP) are compared, and finally a signal noise reduction algorithm with the optimal comprehensive efficiency is screened out. On the basis of algorithm optimization, quantitative mapping rules between microcrack three-dimensional geometric parameters and relative nonlinear coefficients are analyzed through regression modeling, and the significant level of the correlation degree of the relative nonlinear coefficients and microcrack size parameters is effectively improved; and a high-confidence theoretical support is provided for quantitative nondestructive detection of the microcracks in engineering practice.

The invention belongs to the technical field of ultrasonic imaging, and particularly relates to an ultrasonic nonlinear parameter imaging method and system, a medium and a program product. The method comprises the following steps: calculating a fundamental signal and a harmonic signal based on an ultrasonic echo RF signal; extracting the amplitude of the fundamental wave signal and the amplitude of the harmonic wave signal, and calculating to obtain a fundamental wave amplitude ratio and a harmonic wave amplitude ratio; calculating an initial value of a nonlinear coefficient according to a ratio of the fundamental wave amplitude ratio to the harmonic wave amplitude ratio, and estimating a value range of the nonlinear coefficient by using a Newton iteration method; and generating an ultrasonic image based on the value range of the nonlinear coefficient. In the ultrasonic non-linear parameter imaging process, a method for solving a non-linear coefficient by adopting a Newton iteration method is further disclosed, so that the dynamic range of the estimated non-linear coefficient value is expanded, the distinguishing between normal tissues and focus tissues in an obtained ultrasonic image is more obvious, and the sensitivity is higher.

The invention discloses a carbon fiber prepreg laying layer defect detection method and system based on nonlinear guided waves, and the method comprises the steps: arranging excitation and receiving sensor arrays at the inner side and the outer side of a carbon fiber prepreg region, transmitting Hanning window modulation sine wave signals through the excitation sensor arrays, arranging an acoustic metamaterial layer on the surface of a detection region, and detecting the defects of the carbon fiber prepreg laying layer through the acoustic metamaterial layer. An excitation sensor array is divided into two groups to emit different phase signals, so that wave beams are focused at specified positions in a detection area and interact with each other, normalized time-frequency analysis is performed on reference signals and to-be-detected signals, second harmonic components and sideband frequency components are extracted, a relative nonlinear coefficient is calculated based on a signal difference value, and the relative nonlinear coefficient is calculated. And processing and receiving full matrix data of the sensor array by adopting a full focusing method, and reconstructing a nonlinear coefficient distribution image in the carbon fiber prepreg to carry out defect positioning and quantitative evaluation on the acoustic metamaterial layer. According to the invention, accurate and reliable detection and early warning of micro-defects in the carbon fiber prepreg laying process are realized.

The invention discloses a 2-micron-waveband adjustable all-fiber high-repetition-frequency pulse light source generator, belongs to the technical field of laser light source manufacturing, and aims to solve the problem that an existing 2-micron-waveband passive all-fiber mode-locked pulse laser light source is difficult to give consideration to fs-magnitude narrow pulse width and ultra-short-cavity-length high-fundamental-frequency repetition frequency output. The laser comprises a semiconductor laser pumping source, a wavelength division multiplexer, an extrusion type polarization controller I, a polarization-maintaining highly-doped gain fiber, an extrusion type polarization controller II, a long cone region tapering micro-nano fiber, a 2 * 2 fiber coupler and a fiber Faraday mirror. According to the invention, the long-cone micro-nanofiber is introduced into the cavity, and the long-cone micro-nanofiber has the characteristic of high nonlinear coefficient, so that the cavity length can be greatly shortened, enough nonlinear phase shift can be accumulated, and fs-magnitude ultrashort pulse can be output. The device is low in loss, stable in performance and easy to integrate with other optical fiber systems. The laser can be applied to the fields of optical communication, non-metallic material processing, laser medical treatment, intermediate infrared laser pumping sources and the like.

The invention discloses an XLPE cable insulation defect type identification and severity evaluation method. The method comprises the following steps: S1, sample preparation, S2, data acquisition, S3, feature parameter extraction, S4, feature fusion and preprocessing, S5, hierarchical model construction, S6, model training and verification, and S7, model practical application. According to the method, through multi-dimensional feature fusion, dielectric loss (aging overall characterization) and a nonlinear coefficient (local defect sensitivity) are combined, and the recognition accuracy is improved; meanwhile, through a hierarchical model, the defect type is determined firstly, and then the severity is evaluated in a targeted manner, so that feature confusion of different defects can be avoided, and accurate classification and severity quantitative evaluation of the XPLE cable insulation defects are realized; the problem that no diagnosis technology for other defects except for the partial discharge defect exists in XLPE cable insulation at present is solved.

Optical transmission property estimation device comprising:a transmission waveform restoration unit configured to restore a transmission signal from a reception signal obtained by receiving an optical signal by a coherent detection system; andan estimation unit configured to estimate an optical power distribution in a transmission line by estimating a nonlinear coefficient in a propagation equation of a light wave by a linear least square method based on the restored transmission signal and the reception signal.

The present invention discloses a method for determining an on-orbit calibration nonlinear coefficient of a satellite-borne microwave radiometer before launch. The method comprises: sequentially observing three calibration blackbodies by the satellite-borne microwave radiometer to be measured within a scanning cycle to obtain observation voltages and brightness temperatures corresponding to three different temperatures; the three calibration blackbodies comprise: a cold calibration blackbody at the boiling point of liquid nitrogen, a hot calibration blackbody at ambient temperature, and a calibration blackbody at an intermediate temperature between the cold and ambient temperatures; obtaining a secondary calibration curve from the observation voltages and brightness temperatures at the three different temperatures; determining virtual cold space data from the secondary calibration curve through virtual cold space observation; if observation data at an intermediate value between the virtual cold space data and the hot calibration blackbody data can be determined from the virtual cold space data and the hot calibration blackbody data, calculating the nonlinear coefficient from the virtual cold space data and the hot calibration blackbody data; otherwise, calculating the nonlinear coefficient from the virtual cold space data, the hot calibration blackbody data, and the intermediate temperature blackbody data.

This invention belongs to the field of ultrasound imaging technology, specifically relating to an ultrasound nonlinear parameter imaging method, system, medium, and program product. The method includes: calculating a fundamental wave signal and harmonic signals based on ultrasound echo RF signals; extracting the amplitudes of the fundamental wave signal and the harmonic signals, and calculating the fundamental wave amplitude ratio and harmonic amplitude ratio; calculating an initial value of the nonlinear coefficient based on the ratio between the fundamental wave amplitude ratio and the harmonic amplitude ratio, and estimating the range of values ​​for the nonlinear coefficient using Newton's iteration method; and generating an ultrasound image based on the range of values ​​for the nonlinear coefficient. In the process of ultrasound nonlinear parameter imaging, a method for solving the nonlinear coefficient using Newton's iteration method is further disclosed, thereby expanding the dynamic range of the estimated nonlinear coefficient values, resulting in a clearer distinction between normal tissue and lesion tissue in the obtained ultrasound image, and higher sensitivity.

The application discloses a controllable adjustment method and system for a spatial optical soliton motion state, and belongs to the optical field, and comprises the following steps: periodically modulating a transverse refractive index and a nonlinear coefficient in an optical lattice; constructing a nonlinear Schrodinger equation for describing a light beam transmission characteristic based on the optical lattice subjected to the periodic modulation; solving the nonlinear Schrodinger equation by using an equivalent particle method to obtain an optical soliton center position; and based on the optical soliton center position, completing controllable adjustment of the spatial optical soliton motion state through numerical simulation verification. The application periodically modulates the transverse refractive index and the nonlinear coefficient in the optical lattice, derives a new nonlinear Schrodinger equation, solves the nonlinear Schrodinger equation by using the equivalent particle method, analyzes several states of the optical soliton transmission in the optical lattice, and verifies the correctness of the equation through numerical simulation, so that the motion trajectory control problem of the optical soliton transmission in the optical lattice is solved.

The embodiment of the invention discloses an infrared band multi-mode calibration method and device. The method comprises the following steps: calculating a point spread function (PSF) of an original infrared image, and generating a spatial response matching filter function (SRMF) according to the PSF; carrying out two-dimensional convolution calculation on the SRMF to obtain an infrared image after effective space calibration; generating a possible spectral response function of ice pollution, and evaluating an optimal ice pollution spectral response through a cross calibration method; according to the optimal ice pollution spectral response, a spectral response function after possible spectral offset is generated, the optimal possible spectral offset is evaluated through a cross calibration method, and a spectral response function after spectral calibration is obtained through optimal sampling; calculating a linear coefficient, a nonlinear coefficient and a constant coefficient of radiometric calibration; and according to each coefficient of radiometric calibration, calculating the radiation quantity of the infrared image after multi-modal calibration. The method can overcome the existing problems and promote the quantification and multi-source fusion application of the satellite infrared data.

The invention relates to a multi-target equivalent static wind load calculation method suitable for a nonlinear structure. The method comprises the following steps: firstly, carrying out a nonlinear structure wind tunnel test and establishing a corresponding finite element model; secondly, obtaining an average component of the equivalent static wind load through a wind tunnel test result, obtaining an equivalent static wind load not including the average component through time-history analysis of a finite element model, namely a pulsation component, and obtaining a multi-target linear equivalent static wind load through combined analysis of the pulsation component and the average component; and finally, on the basis of the multi-target linear equivalent quiet wind load, correcting the multi-target linear equivalent quiet wind load in combination with a nonlinear coefficient, calculating to obtain a multi-target nonlinear equivalent quiet wind load, and expressing the multi-target nonlinear equivalent quiet wind load as a wind pressure coefficient form. The simultaneous equivalence of multiple extreme responses of a nonlinear structure is realized, and a convenient and accurate equivalent static wind load is provided for engineering design.

This invention discloses a system and method for monitoring the hydrogen damage state of metals, comprising: a hydrogen charging device for electrochemically charging a plate-shaped sample of the same metal as the target metal that has not undergone hydrogen damage; a hydrogen permeation measuring device for converting hydrogen atoms permeating into the sample into hydrogen ions during the hydrogen charging process and measuring the current generated by the free electrons produced during the conversion process in real time to obtain a hydrogen permeation curve; and an ultrasonic measuring device for emitting ultrasonic guided waves to the sample during the hydrogen charging process and receiving the nonlinear response signal generated by the guided waves exciting ultrasonic waves inside the sample, and then performing cepstral analysis on the received signal to obtain the nonlinear coefficients at different time periods. Based on this, combined with the hydrogen permeation curve, the correlation between the nonlinear response signal and the degree of hydrogen damage is determined, and then the nonlinear response signal of the target metal is substituted into the correlation to obtain the hydrogen damage state inside the metal. This invention can monitor and evaluate the degree of hydrogen damage inside metals in real time.

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for applying non-linearity to digital subcarriers. A receiver includes a detector circuit operable to receive a first optical signal over an optical link, the first optical signal carrying first data. The receiver includes a carrier recovery estimation circuit operable to generate compensated data by correcting errors in the first data. The receiver includes a non-linear coefficient estimation circuit operable to (i) receive the compensated data, and (ii) estimate one or more non-linear coefficients, wherein information indicative of the estimated non-linear coefficients is transmitted over an optical network, such that a second optical signal is transmitted based, at least in part, on the estimated non-linear coefficients, the second optical signal being received by the receiver.

An optical nonlinearity measurement method according to the present disclosure utilizes photon pair generation through a spontaneous four-wave mixing process, to observe photon pairs using an optical waveguide loaded with a two-dimensional material. Compared with the Z-scan method, the influence of free carriers on nonlinear refractive indexes is only indirect. With a parameter being the length of the attached two-dimensional material in the optical waveguide direction, a theoretical value of the coincidence rate of the photon pairs based on the coupled wave equation is fitted to a measured value of the coincidence rate of the photon pairs. For the coincidence rate of the photon pairs, the theoretical value based on the coupled wave equation is fitted to the measured value in a state reflecting the structure of the optical waveguide loaded with the two-dimensional material, and nonlinear coefficients γ1 and γ2 at that time are obtained.

This invention discloses a numerical inversion method for nonlinear stress fields, comprising: selecting a study area and constructing a three-dimensional geological model; discretizing the boundary surface of the three-dimensional geological model into multiple surface elements, assigning a nonlinear variation coefficient to each surface element to generate the nonlinear variation coefficient of the model boundary surface; determining the stress components with significant influence on the study area based on measured geostress values ​​as linear boundary conditions applied to the model; adjusting the nonlinear coefficients of the linear boundary conditions to obtain nonlinear boundary conditions; determining the calculated stress component values ​​at measured points under preset working conditions based on the nonlinear boundary conditions; determining the regression coefficients for each preset working condition using the principle of linear superposition and the least squares method based on the measured and calculated stress component values; and generating a nonlinear geostress field based on the nonlinear boundary conditions and regression coefficients and a numerical calculation model. This method achieves the loading of nonlinear stress boundaries, thereby determining the optimal nonlinear geostress field.

This invention discloses a method for extracting radio frequency fingerprints of broadband signals based on nonlinear features, comprising the following steps: extracting all preamble symbol groups from the received signal frame and performing preprocessing; constructing a matrix using the known preamble signal to obtain the vector value of the nonlinear coefficient mixed with multipath propagation; eliminating multipath effects based on the vector value to obtain a fingerprint value containing only nonlinear features; obtaining the nonlinear feature value of the mixture of nonlinear coefficient and local preamble based on linear convolution rules; and combining the above values ​​containing only nonlinear coefficients with the values ​​of the mixture of nonlinear coefficient and local preamble to provide a reliable transmitter identification method as a nonlinear fingerprint. The radio frequency fingerprint extraction method proposed in this invention is less affected by channel conditions and has high feature dimension scalability, thus providing a technical means for high-precision transmitter identification using radio frequency fingerprinting technology.

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

The invention provides a low-complexity nonlinear compensation method and system for digital subcarrier multiplexing optical communication, and the method comprises the steps: calculating a nonlinear coefficient of a digital subcarrier multiplexing optical communication system, and carrying out the quantization processing of the nonlinear coefficient through employing a uniform quantization mode; by taking the cross-section length as a processing step length, converting the time domain signal of each subcarrier to a frequency domain for dispersion compensation, and then converting the compensated signal back to the time domain; calculating nonlinear phase noise in the subcarriers based on the time domain signal intensity of each subcarrier by taking the cross-section length as a processing step length, and performing phase rotation compensation; and calculating inter-subcarrier nonlinear phase noise and inter-polarization crosstalk based on the quantized nonlinear coefficient, subcarrier signal strength and inter-polarization crosstalk strength by taking the cross-section length as a processing step length, constructing a nonlinear compensation matrix and performing matrix compensation. According to the invention, the calculation complexity of an optical fiber nonlinear compensation algorithm is reduced, and efficient nonlinear compensation of a digital subcarrier multiplexing optical communication system is realized.

The invention discloses a large dynamic reverse demodulation method and device based on a TDMA (Time Division Multiple Access) system. The method comprises the following steps: maintaining and storing a terminal portrait lookup table of received power statistics of each terminal; before the target time slot of the terminal arrives, predicting the received power distribution of the terminal based on the portrait, and constructing a risk objective function for balancing overload risk and quantitative loss; an optimal pre-cut gain is determined by optimizing the function. In the login time slot, the absolute gain deviation and the nonlinear coefficient of the receiving link are further estimated by using the coded power reference pilot frequency on the basis of applying the pre-cut gain, and the secondary calibration gain and the linearization compensation parameter are calculated. In a subsequent service time slot, demodulation is carried out by using secondary calibration gain and linear compensation. And after demodulation, updating the terminal portrait in a closed loop by using the actually measured power. According to the invention, through predictive risk minimization gain decision and nonlinear online compensation, accurate and adaptive gain control is realized, and the receiving performance and the dynamic range of the system are improved.

The present application belongs to the field of ultrafast laser and nonlinear optics, and particularly relates to a near-infrared few-cycle pulse generation system and method based on high-pressure nonlinear enhancement. The method fills inert gas into a hollow-core anti-resonant optical fiber and adjusts the gas pressure to the high-pressure interval of 20 bar-90 bar, enhances the nonlinear coefficient of the gas to realize the dispersion and nonlinear dynamic balance of the pulse in the waveguide, thereby compensating for the insufficient peak power of the low-energy pump pulse. The pulse feedback module collects the output time-domain intensity waveform and extracts the main peak energy proportion and the splitting factor as feedback indexes. The control module diagnoses the offset state of the self-compression focal point relative to the truncated end face according to the feedback indexes, controls the small-step pressure regulation of the gas pressure regulation module to anchor the focal point on the truncated end face, and directly outputs high-quality and high-coherence near-infrared few-cycle pulses without external dispersion compensation devices.

The embodiments of the present disclosure disclose an infrared waveband multi-modal calibration method and device. The method comprises: calculating a point spread function (PSF) of an original infrared image, and generating a spatial response matching filter function (SRMF) according to the PSF; performing two-dimensional convolution calculation on the SRMF to obtain an infrared image after effective spatial calibration; generating a possible spectral response function affected by ice pollution, and evaluating an optimal ice pollution spectral response by a cross-calibration method; generating a possible spectral response function after possible spectral shift according to the optimal ice pollution spectral response, and evaluating an optimal possible spectral shift amount by the cross-calibration method, and obtaining a spectral response function after spectral calibration by optimal sampling; calculating a linear coefficient, a nonlinear coefficient and a constant coefficient of radiation calibration; and calculating an infrared image radiation after multi-modal calibration according to the coefficients of radiation calibration and. The method can overcome existing problems and promote quantitative satellite infrared data and multi-source fusion application.

The invention provides a harmonic correction method and device for a high-precision analog-to-digital converter, electronic equipment and a medium, and the method comprises the steps: obtaining a set step length and an index coefficient, inputting the index coefficient and the set step length into a preset analog-to-digital converter, constructing an analog-to-digital conversion operation relational expression, constructing a positive offset relational expression and a negative offset relational expression on the basis of the analog-to-digital conversion operation relational expression, so as to determine the change direction of the set step length according to the second harmonic power of the two offset relational expressions; and extracting harmonic distortion of a calculation result of the analog-to-digital conversion operation relational expression, adjusting an index coefficient based on the harmonic distortion and a preset harmonic distortion threshold value, and determining a nonlinear coefficient according to the adjusted index coefficient and a set step length so as to correct corresponding harmonic waves. According to the harmonic correction method provided by the invention, the nonlinear coefficient of each order of the analog-to-digital converter is rapidly obtained through an indirect measurement mode, the harmonic of the high-precision analog-to-digital converter is conveniently and accurately corrected, and the yield and the consistency of a circuit are improved.

The invention provides a non-reference damage imaging method based on nonlinear Lamb waves and Bayesian inference, and relates to the field of damage imaging, and the method specifically comprises the following steps: collecting nonlinear Lamb wave signals of a plurality of propagation paths; an enhanced second harmonic signal is obtained through a pulse inversion technology; extracting a flight time feature of the envelope signal; the frequency spectrum of the nonlinear Lamb wave signal is obtained through fast Fourier transform, and nonlinear coefficient damage index features are obtained through calculation; feature level fusion is carried out based on Bayesian estimation; and solving a posterior probability density function of the damage position parameter by using Hamiltonian Monte Carlo sampling, and carrying out damage probability imaging positioning according to posterior probability distribution. According to the technical scheme, the problems that in the prior art, a large number of sensors usually need to be deployed, and the dual requirements for high-precision damage detection and sensor number minimization in engineering practice are difficult to meet are solved.

This invention discloses a performance analysis method, apparatus, terminal device, and storage medium for hard-isolated passive optical fiber (POB) networks. The method constructs a simulation model characterizing the propagation of optical signals in each channel of the POB network based on the group velocity dispersion parameters, preset attenuation coefficients, and preset nonlinear coefficients. The simulation model is then solved to obtain an approximate analytical solution characterizing the temporal and spatial variations of the optical signal in each channel. Based on this approximate analytical solution, the bit error rate (BER) and achievable information rate (RI) of each channel in the POB network are calculated. Finally, the performance analysis results of the POB network are generated based on the BER and RI. Compared to existing laboratory testing methods, this invention achieves the goal of low-cost and efficient performance analysis of hard-isolated POB networks.

The invention discloses a method and a device for detecting the interface pressure of a combined prefabricated intermediate joint of a high-voltage cable. The method comprises the following steps: acquiring an ultrasonic echo signal of an intermediate joint of a to-be-detected cable; performing spectral analysis on the ultrasonic echo signal to obtain a fundamental wave amplitude and a second harmonic amplitude; calculating a nonlinear coefficient according to the fundamental wave amplitude and the second harmonic amplitude; and according to the nonlinear coefficient and a pressure calibration curve constructed through a pressure loading experiment, determining the interface pressure of the intermediate joint of the to-be-tested cable.

The application discloses a kind of nonlinear ultrasonic time-frequency dual-branch modal fusion concrete damage identification methods, it is related to nondestructive testing technical field.The application is identified to concrete micro-damage by fusing time domain, frequency domain dual-branch and the multimodal deep learning model of nonlinear coefficient;In time domain branch, the time domain characteristics and time sequence dependent relationship of nonlinear ultrasonic signal are jointly modeled by combining wavelet energy analysis and multi-scale time domain block time series analysis;In frequency domain branch, the effective extraction and adaptive weighting of spectral feature are realized by using lightweight convolutional neural network and introducing attention mechanism;At the same time, a variety of nonlinear coefficients are integrated into feature fusion stage to enhance damage representation ability;As described above, the application can improve nonlinear ultrasonic recognition concrete damage efficiency, while ensuring the accuracy of concrete damage identification.

The application discloses a microstrip line passive intermodulation prediction method based on a nonlinear coefficient R n , and belongs to the technical field of passive intermodulation prediction. The application obtains a parameter nonlinear coefficient R2 based on an edge defect index of a microstrip line, applies a multiple linear regression method, and establishes a passive intermodulation prediction model to predict third-order passive intermodulation power levels of the microstrip line under different processes. The mapping relation between the microscopic defect index and the nonlinear coefficient is substituted into an expression for solving third-order passive intermodulation transmission and reflection power, the error between the prediction and the test result is within the range of ±6 dB, and a feasible method is provided for the prediction and analysis of the third-order passive intermodulation power of the microstrip line.

This invention discloses a measuring device and method for detecting the nonlinear coefficient and attenuation coefficient of surface waves on a main beam, relating to the technical field of cranes. It solves the problem of difficulty in online measurement of fatigue damage state assessment parameters for crane main beams. The device includes: a piezoelectric surface wave transducer and two dual-electrode piezoelectric thin-film sensors, both pressed firmly onto the surface of the steel plate to be tested; the dual-electrode piezoelectric thin-film sensor closer to the piezoelectric surface wave transducer is designated as sensor number one, and the dual-electrode piezoelectric thin-film sensor farther from the transducer is designated as sensor number two; the piezoelectric surface wave transducer is used to excite surface waves, and sensors number one and two are used to receive surface waves. In this invention, the measuring device is fixed using magnets, making it easy to install and remove, reliably fixed, and compact, adaptable to the working environment of cranes.

This invention belongs to the field of mechanical analysis technology and provides a method and system for elastic beam deformation analysis based on fourth-order nonlinear differential equations. The method includes: obtaining the stress-strain relationship and lateral displacement function of the elastic beam; constructing a fourth-order nonlinear mechanical response function of the elastic beam based on the obtained stress-strain relationship and lateral displacement function; solving the constructed fourth-order nonlinear mechanical response function to identify the local buckling location and higher-order shear effects of the elastic beam; taking the minimum weight of the elastic beam as the objective function, considering the displacement and stress constraints of the elastic beam, performing sensitivity analysis of the elastic beam based on the obtained local buckling location and higher-order shear effects, adjusting the nonlinear coefficient of the elastic beam, and completing the elastic beam deformation analysis based on fourth-order nonlinear differential equations.