66 results about "Amplitude ratio" patented technology

The invention relates to the technical field of fault detection, and discloses a diesel generating set fault detection method and system based on deep learning, and the method comprises the steps: obtaining first vibration signal data, and carrying out the time-frequency decomposition, and obtaining a dynamic change feature; de-noising processing is carried out on the dynamic change features to obtain a time-frequency feature sequence; extracting a peak energy distribution data set, and calculating each frequency band entropy value to obtain a frequency band entropy value sequence; classifying the frequency band entropy sequence, determining a random fluctuation reference mode, and separating to obtain an abnormal frequency component; calculating a spectral line spacing and amplitude ratio, obtaining a spectral line feature data set, classifying the spectral line feature data set, and determining a fault classification result; obtaining current second vibration signal data, performing similarity calculation on the current second vibration signal data and a pre-established normal mode library, and outputting a fault feature vector; and verifying the fault feature vector to obtain a final fault detection result. According to the method, closed-loop diagnosis from signal acquisition to fault classification can be realized, and the fault detection precision of the diesel generating set is improved.

The invention discloses a double-frequency anti-interference ultrasonic water meter and a metering method thereof, and relates to the technical field of fluid metering. A 500kHz sound velocity reference channel is constructed in a self-transmitting and self-receiving mode of a single transducer, the sound path length under solidified pure water is calibrated through a factory, the current water quality sound velocity is calculated in real time in a zero flow state, the zero offset of a 1MHz main channel is dynamically corrected, and a high-precision temperature sensor is omitted. Meanwhile, online water quality diagnosis is realized by utilizing a double-frequency cooperation mechanism: turbidity is quantized according to the amplitude ratio of 500kHz and 1MHz signals (based on the characteristics of high-frequency scattering sensitivity and high low-frequency penetrability), and bubbles are detected according to the time domain volatility of the 1MHz signals; and dynamically optimizing the flow metering precision of the main channel according to a diagnosis result by combining a sound velocity compensation model (the sound velocity is inversely proportional to the turbidity) and a graded bubble compensation model (the sound velocity or the flow is corrected according to the volatility). According to the method, medium interference is effectively overcome, measurement reliability is improved, and real-time monitoring and reporting of basic water quality (turbidity and bubbles) are achieved at low cost.

The invention discloses an asymmetric coupling rigidity disturbance type MEMS modal localization accelerometer and a detection method. The accelerometer comprises an upper signal conversion layer and a lower glass substrate layer. The upper signal conversion layer comprises a sensitive mass block, a supporting structure and asymmetrical coupled resonator pairs which are symmetrically distributed. According to the asymmetric coupling resonator pair, a first type resonator and a second type resonator form a weak coupling system through electrostatic coupling, the first type resonator is fixed to a glass substrate layer through anchor points, the second type resonator is fixed to a sensitive mass block, and the first type resonator and the second type resonator meet the mass and rigidity asymmetric relation. When being subjected to the acceleration effect, the sensitive mass block generates micro displacement, changes the static coupling rigidity and triggers the modal localization effect, so that the amplitude ratio of the two resonators is changed, and acceleration measurement is realized by detecting the amplitude ratio change. By adopting the asymmetric structure, the sensitivity of the accelerometer is doubled compared with that of a symmetric structure, and meanwhile, the accelerometer has good linearity and anti-interference capability.

The invention provides a CEEMDAN-SSA-based power distribution network fault identification method, and the method comprises the steps: receiving a traveling wave signal of a power distribution network, and carrying out the preprocessing of the traveling wave signal; decomposing the preprocessed traveling wave signal by adopting CEEMDAN to obtain an intrinsic mode function component set, and selecting a high-frequency intrinsic mode function component from the intrinsic mode function component set; performing noise reduction on the high-frequency intrinsic mode function component by using singular spectrum analysis to obtain a pure fault feature signal; analyzing and reconstructing the frequency spectrum characteristics of the pure fault characteristic signal by using fast Fourier transform, and calculating the average frequency spectrum content of the low-frequency-band signal and the amplitude ratio of the high-frequency-band signal according to the frequency spectrum characteristics; and generating a fault identification result of the power distribution network by taking the average frequency spectrum content of the low-frequency-band signal as a main criterion and taking the amplitude proportion of the high-frequency-band signal as an auxiliary criterion according to the fault traveling wave transmission characteristics. Therefore, high-precision power distribution network fault identification can be realized in a complex working condition and a high-noise environment.

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

The invention relates to the technical field of seismic exploration, in particular to a method for determining structural parameters and sweep frequency signals of a controllable impact seismic source, which is used for carrying out an indoor physical test of a controllable impact seismic source model machine and ensuring the effectiveness of a design scheme of the controllable impact seismic source. Constructing and verifying a multi-body dynamics numerical model of single impact, performing single variable sensitivity analysis on key structure parameters, and determining an optimal structure parameter combination by taking a frequency domain of output seismic waves as an evaluation index; constructing a multi-impact model, performing a simulation test on the sweep frequency control parameter, and determining an optimal sweep frequency signal parameter based on the main lobe amplitude and the main lobe-side lobe amplitude ratio of the output signal autocorrelation function; through forward modeling and cross-correlation-scattered wave inversion imaging processing, an application method of a controllable impact seismic source is established, and validity is verified. The technical problems that a traditional trial and error method is low in efficiency, main lobe energy of seismic source output signals is dispersed due to an unknown parameter influence mechanism, side lobe interference is large, and the signal-to-noise ratio is low are solved.

This invention relates to a method for measuring the stability margin of a constant-temperature hot-wire anemometer based on in-situ open-loop frequency characteristics, belonging to the field of fluid measurement and automatic control technology. The method disclosed in this invention includes the following steps: S1. Connecting an ultra-low frequency low-pass filter to the closed-loop circuit to form an in-situ open-loop system with a DC closed loop and an AC open loop; S2. Injecting a sweep frequency excitation signal E at the bias circuit. stimu And measure the output response E of the amplifier circuit. a By comparing the amplitude ratio and phase difference of the two, the open-loop frequency response G of the system under actual operating conditions of the hot wire is obtained. open (jω); S3. According to G open (jω) Obtain the phase margin of the system and determine its stability. This invention proposes a new method for measuring the stability margin of a constant-temperature hot-wire anemometer, transforming the complex system stability problem into a measurable and analyzable open-loop frequency characteristic stability margin problem, providing a direct and reliable engineering basis for the circuit design of constant-temperature hot-wire anemometers.

This application relates to the field of electromagnetic waves, specifically providing a polarization state detection method and apparatus. The method utilizes a polarization state detection device for detection and includes: inputting the beam to be detected into the polarization state detection device to obtain orthogonal first and second Bessel beams; using a polarizer to obtain the azimuth angles corresponding to the interference weakening or enhancement regions in the interference patterns of the first and second Bessel beams, and determining the phase difference between the first and second Bessel beams based on the azimuth angles; using the polarizer to obtain the first amplitude of the first Bessel beam and the second amplitude of the second Bessel beam, respectively, and obtaining the amplitude ratio based on the first and second amplitudes; and calculating the polarization state of the wave to be detected based on the phase difference and amplitude ratio. This polarization state detection method simplifies the polarization state detection process for terahertz and millimeter waves, promoting the miniaturization and integration of detection equipment.

This improves the reliability and throughput of characteristic measurement of films formed on substrates. [Solution] Polarization components consisting of p-polarized and s-polarized terahertz waves with mutually orthogonal vibration planes are incident on a substrate, the time waveforms of the electric field strengths of the p-polarized and s-polarized waves are obtained from the time waveform of the electric field strength of the polarization components reflected from the substrate, the spectra of the measured amplitude ratio of the p-polarized and s-polarized waves and the spectra of the measured phase difference of the p-polarized and s-polarized waves are obtained, the spectra of the calculated amplitude ratio of the p-polarized and s-polarized waves and the spectra of the calculated phase difference of the p-polarized and s-polarized waves are obtained by simulation using an optical model of the substrate, the properties of the film formed on the substrate are measured by fitting which at least matches the spectra of the calculated amplitude ratio to the spectra of the measured amplitude ratio, and the most reliable measurement value is used from among the multiple measurement values ​​used when measuring the properties of the film.

The application discloses a three-dimensional positioning method of a seismic source based on a multi-channel amplitude ratio. The method obtains waveform data of the same event on at least four sensor channels and spatial coordinates of the sensors, pre-processes the waveforms, determines an event window corresponding to the event, extracts amplitude indicators of each channel in the event window and performs channel consistency correction, constructs an amplitude logarithm ratio observation on an arbitrary channel based on an exponential decay model to eliminate a source intensity factor, and further forms a constraint related to a distance difference of the seismic source and the sensor. A redundant channel constraint set is further constructed, and an abnormal channel is down-weighted or removed. A weighted nonlinear least square is used in combination with an iterative reweighted least square or a robust loss function to solve the problem, a residual threshold is determined and is updated with iteration. A plurality of candidate solutions are obtained by solving a multi-initial value or a coarse grid initial value in a preset feasible region, and an optimal solution is output. The method reduces the dependence on the arrival time picking, and can be used for microseismic monitoring, acoustic emission positioning and underground engineering safety monitoring.

The embodiment of the invention relates to the technical field of seismic data processing, in particular to a frequency band width determination method and device, equipment, a medium and a product program. The invention provides a method for determining a frequency bandwidth. The method comprises the following steps: determining the total amplitude of target channel data in shot gather data; determining an amplitude ratio between the amplitude of each frequency in the target channel data and the total amplitude; determining a target frequency set of high-amplitude frequencies meeting a preset condition according to the amplitude ratio; constructing a kernel density curve according to the target frequency set; and determining the frequency band width of the low-frequency high-amplitude data according to the kernel density curve. According to the method, the problem that seismic traces containing low-frequency high-amplitude data in seismic trace data cannot be determined is solved, whether high-amplitude low-frequency data is needed in the seismic trace data or not is quickly determined, and if the high-amplitude low-frequency data exists, the frequency band width of the low-frequency data is quickly positioned.

The application discloses a kind of self-adapting noise reduction filtering method, system, medium and equipment, the method includes to input dynamic signal and carry out direct current offset preprocessing;Time-frequency representation matrix is generated by time-frequency transform, and amplitude spectrum is calculated accordingly;Along time axis analysis amplitude spectrum, extract short time and long time noise amplitude and fusion generate basic noise amplitude;Signal noise amplitude ratio is calculated based on basic noise amplitude, and final noise amplitude is determined;According to final noise amplitude, calculate noise reduction spectrum amplitude, retain original phase information, reconstruct as noise reduction time domain signal by inverse transform;The system includes preprocessing module, amplitude spectrum generation module, double time scale noise estimation module, denoising module, noise reduction and signal reconstruction module;The application is accurately described by double time scale noise estimation Dynamic distribution of noise, combined with the adaptive noise reduction adjustment based on signal noise amplitude ratio, effectively suppress complex, non-stationary noise, while enhancing the relative intensity of characteristic frequency band.

The invention discloses an adaptive integrated empirical mode decomposition method based on a quartile difference algorithm. The adaptive integrated empirical mode decomposition method comprises the following steps: inputting an initial decomposition signal; initializing a value range for adding white noise amplitude ratio coefficients and an amplitude ratio coefficient interval value, and gradually increasing the white noise amplitude ratio coefficients in the value range by taking the quartile difference of the initial decomposition signal as a reference to obtain white noise corresponding to each white noise amplitude ratio coefficient; sequentially adding white noise into the initial decomposition signal from small to large to obtain a noise-added decomposition signal; solving a local maximum value point position and a local minimum value point position of the noise-added decomposition signal to obtain a sequence formed by maximum value points and a sequence formed by minimum value points; calculating a quartile difference between the maximum value point sequence and the minimum value point sequence by adopting a quartile difference calculation method to obtain an extreme point distribution characteristic of the noise-added decomposition signal and a corresponding change relation curve between the extreme point distribution characteristic and a coefficient; obtaining the optimal value of the added white noise amplitude ratio coefficient according to the corresponding change relation curve; and performing integrated empirical mode decomposition on the initial decomposition signal by using the optimal value to obtain an n-order intrinsic mode component. By using the method, the purpose of adaptively optimizing decomposition parameters according to actual decomposition signals in integrated empirical mode decomposition can be achieved, signal extreme points are distributed more uniformly, the fluctuation degree is as small as possible, mode aliasing is reduced, and adaptive decomposition of nonlinear and non-stationary signals is achieved.

The invention discloses an electrosurgical tissue impedance measurement system and method based on frequency domain analysis. The system comprises a main energy generation module, a modulation signal generation module, an output superposition module, a signal acquisition module, an impedance calculation module and a feedback control module. The main energy generation module outputs a high-frequency main waveform for tissue cutting or blood coagulation; the modulation signal generation module is used for generating a modulation signal, and the modulation signal comprises one of a multi-cosine signal or a multi-frequency sweep-frequency signal and a pseudo-random sequence; the output superposition module is used for superposing the modulation signal into the main waveform; the signal acquisition module synchronously acquires tissue voltage and current signals after the modulation signal is loaded; the impedance calculation module is used for performing frequency domain analysis on the voltage and current signals acquired by the signal acquisition module, extracting frequency components corresponding to modulation signals by using fast Fourier transform (FFT), phase lock detection (PLL) or a time-frequency analysis algorithm, and performing frequency domain analysis on multi-cosine signals or frequency sweep signals; by comparing the amplitude ratio and the phase difference of the corresponding frequency components of the modulation signal output end and the response end, the impedance Z = RZ < Z of the measured tissue is inverted according to the known reference impedance, and Z is the impedance of the measured tissue; rZ is the amplitude of the measured impedance and reflects the magnitude of the impedance; < Z represents the phase difference between the voltage and the current; for a pseudo-random sequence signal, a matched filter is used for carrying out related detection on an input signal, and a pseudo-random sequence value is extracted so as to obtain a system signal and control data; a feedback control module adjusts the output power or the cutting / coagulation mode of the electrosurgical equipment in real time according to the tissue impedance obtained through calculation and the dynamic change of the tissue impedance; wherein the dynamic change is a group of dynamic sequence values of the impedance of the measured tissue from the time dimension. By means of the design, real-time accurate measurement can be achieved, the anti-interference capability is high, errors are small, and efficient and safe cutting / blood coagulation can be achieved.

The invention discloses a sub-pixel positioning method, system and device based on a signal amplitude ratio and a medium, and is applied to the technical field of semiconductor radiation detection and imaging, and the method comprises the steps: obtaining induction signals generated by the same energy deposition event in at least two adjacent pixel units; processing the sensing signal to obtain digital amplitude values respectively corresponding to the at least two pixel units; calculating an amplitude ratio according to the digital amplitude value; determining sub-pixel level position information of the energy deposition event relative to the at least two pixel units according to the amplitude ratio based on a preset mapping relation between the amplitude ratio and the sub-pixel position; outputting a positioning result containing the sub-pixel level position information; according to the invention, the precise function relation between the amplitude ratio of the adjacent pixel induction signals and the action position is established, so that the high-precision positioning of the sub-pixel level can be realized through simple and efficient calculation, and the spatial resolution of the detector is remarkably improved.

The invention discloses a dangerous rock mass stability evaluation method and system based on an amplitude ratio and a frequency ratio, and relates to the technical field of geological disaster risk assessment, and the method comprises the steps: collecting dangerous rock three-way vibration data and bed rock three-way vibration data in the same time interval; the dangerous rock three-dimensional vibration data and the bedrock three-dimensional vibration data are synthesized into dangerous rock one-dimensional amplitude data and bedrock one-dimensional amplitude data respectively, and the ratio of the dangerous rock amplitude standard deviation to the bedrock amplitude standard deviation is calculated to obtain an amplitude ratio; calculating the ratio of the dangerous rock peak frequency to the bedrock peak frequency to obtain a frequency ratio; and inputting the amplitude ratio and the frequency ratio as inputs into a trained dangerous rock mass stability evaluation model, and identifying the stable state of the dangerous rock mass. According to the method, the problem that the accuracy of a stability evaluation result is insufficient due to excitation and equipment temperature drift in dangerous rock mass vibration monitoring in the prior art is solved.

The invention relates to the technical field of image processing, and discloses a coke quality stability evaluation method comprising the following steps: step S101, obtaining a normalized angle frame sequence; s102, performing weighted least square fitting on the curve of the intensity of each pixel changing along with the polarization angle; step S103, obtaining a pixel-level polarization biharmonic normalization amplitude ratio; step S104, obtaining a field-of-view polarization biharmonic normalized amplitude ratio; step S105, obtaining a stability distance; and S106, obtaining a polarization stability index. According to the method, the influence of gain drift is eliminated through angle frame space mean value normalization, a harmonic projection layer adapts to non-equiangular or unfilled corner sampling through weighted least squares and generates a reliability weight to eliminate abnormal angle frame interference, and visual indexes are output by combining effective domain screening, distribution comparison quantification batch difference and index mapping. Therefore, the anisotropy and stability characteristics of the coke can be accurately reflected.

The invention discloses a step frequency imaging method based on speed matched filtering and false scattering point elimination, and the method comprises the steps: firstly, obtaining a distance unit corresponding to the maximum amplitude in a non-coherent processing channel and a speed matched filtering result, and calculating a target compensation speed range; traversing each speed value in the compensation speed range, and generating a target one-dimensional range profile corresponding to different speeds according to the sub-pulse data; taking the ratio of the kurtosis of the range profile to the envelope entropy as a cost function, and taking the range profile corresponding to the maximum cost function as a range profile after speed compensation; and finally, calculating a scattering point correlation coefficient by using the distance image after speed compensation and the scattering point sample, performing false scattering point judgment according to the scattering point correlation coefficient and an amplitude ratio, and obtaining a high-resolution one-dimensional distance image of the target through false scattering point elimination. According to the invention, accurate estimation of the target speed is realized, the imaging accuracy of the step frequency system is improved, and the measurement and calculation precision of detection target parameters is improved.

The invention discloses a trace water content detection method based on a tunable laser absorption spectrum, and relates to the technical field of gas moisture detection.The method comprises the steps that a laser generating device is adopted to generate an optical signal, the optical signal is irradiated into an integrated small gas chamber storing to-be-detected gas, and a first harmonic signal and a second harmonic signal of the optical signal passing through the to-be-detected gas are collected; performing light energy compensation by using the first harmonic signal and the second harmonic signal to obtain an inversion parameter; and performing water vapor concentration nonlinear fitting inversion by using the inversion parameters to obtain the moisture content of the gas to be detected. The extracted first harmonic signal and the extracted second harmonic signal are utilized, and a stable signal amplitude ratio is adopted as a subsequent processing signal. The signal amplitude ratio makes the detection signal no longer depend on the absolute value of the light intensity, but is determined by the relative relationship between the two harmonic components. The influence of light intensity fluctuation is compensated, periodic noise such as optical interference fringes is inhibited to a certain degree, and then rapid and high-precision detection of the gas water content is achieved.

The invention proposes a system for monitoring the vibrations, in particular the natural frequency, of a tower (1) of a wind turbine (2), comprising vibration sensors (3) associated with the tower (1) and comprising an evaluation device (4) for processing vibration sensor data. In order to be able to make reliable statements about damage to the tower (1), it is proposed that a plurality of vibration sensors (3) are arranged annularly around the tower axis (6) in three or more tower cross-sectional planes (5) along the tower axis (6), wherein the evaluation device (4) stores, in addition to the natural frequency (fi), vibration amplitudes (A) associated with the respective tower cross-sectional planes (5) at observation times (Ti) and identifies structural damage in the tower (1) by way of comparing the natural frequencies (fi) and the amplitude ratios (A) over an observation period.

The application discloses a Loran-C carrier phase tracking method and system considering sky wave interference, and relates to the technical field of radio signal reception. The specific implementation scheme is as follows: a sky wave and a ground wave are separated to obtain an amplitude ratio and a time delay difference, and whether the sky wave is strong is determined according to the amplitude ratio; a phase discrimination correction number is calculated based on the amplitude ratio and the time delay difference, and an integral interval A of in-phase branch and quadrature branch signals of a carrier phase tracking loop is determined; the in-phase branch signal and the quadrature branch signal are integrated according to the integral interval A, a phase discrimination result is calculated, the phase discrimination result is corrected to obtain a phase discrimination correction value; and the local carrier is adjusted based on the phase discrimination correction value to realize carrier phase tracking. The method of the application expands the effective length of the Loran-C signal used for carrier phase tracking, optimizes the phase discrimination process of the Loran-C carrier phase tracking algorithm, and improves the carrier phase tracking performance.

The invention discloses a three-dimensional Rayleigh wave attenuation relative variation imaging method taking a stable plot as a reference value, relates to the technical field of Rayleigh wave attenuation relative variation measurement, and aims to solve the problems that in the prior art, a seismic source and a path effect are difficult to effectively strip, and a medium attribute change signal cannot be directly extracted. The invention aims to improve the capability of monitoring the change of the state of the earth crust medium and improve the recognition precision of the earthquake precursor abnormity. Comprising the following steps: respectively calculating Rayleigh wave amplitude ratios of seismic stations in a research area and a reference area to two seismic events; correcting the amplitude ratio of the seismic station in the research area by using the amplitude ratio of the seismic station in the reference area, and calculating to obtain the relative variation of the Rayleigh wave attenuation coefficient of the medium of the station in the research area between the two seismic events; on the basis of relative variation of attenuation coefficients calculated by multiple stations and multiple frequencies, spatial interpolation is performed on each single-frequency data to generate a two-dimensional plane distribution diagram, and then different-frequency two-dimensional diagrams are combined according to corresponding depths to generate a three-dimensional space distribution image.

[Problem] To increase the reliability and throughput of measurement of the properties of a film formed on a substrate. [Solution] A substrate is illuminated with polarization components consisting of p-polarization and s-polarization of terahertz waves with mutually orthogonal planes of vibration. Time waveforms of the electric field intensities of the p-polarization and the s-polarization are acquired from a time waveform of the electric field intensity of a polarization component reflected from the substrate. A spectrum of an actually measured amplitude ratio of the p-polarization and the s-polarization, and a spectrum of an actually measured phase difference between the p-polarization and the s-polarization are acquired. A spectrum of a calculated amplitude ratio of the p-polarization and the s-polarization, and a spectrum of a calculated phase difference between the p-polarization and the s-polarization are acquired through simulation using an optical model of the substrate. The properties of a film formed on the substrate are measured by fitting involving at least alignment of the spectrum of the calculated amplitude ratio with the spectrum of the actually measured amplitude ratio. Among a plurality of measurement values used in the measurement of the properties of the film, those with high reliability are employed.

This application relates to the field of equipment condition monitoring technology, and discloses a method and system for fault diagnosis of the secondary circuit of a current transformer. The method includes: connecting a detection device in series to the secondary circuit to establish a physical circuit; injecting a step-scanning high-frequency excitation signal; synchronously sampling the input power signal and output voltage signal to obtain time-series discrete data; performing a fast Fourier transform on the data to extract the frequency domain complex components; calculating the amplitude ratio and phase difference at different scanning frequencies to generate a joint amplitude-frequency-phase-frequency distribution curve; extracting fusion features from the curve; dividing the dataset after normalization; constructing a basic classifier based on the LightGBM algorithm; introducing the TPE algorithm for hyperparameter global optimization; training a state identification model and outputting fault diagnosis results; and using the SHAP interpretation model to calculate the contribution value of the fusion features and outputting feature distribution information. This invention improves the accuracy and engineering interpretability of secondary circuit fault classification.

The application relates to a single-pole cross-ring antenna signal direction finding method combining amplitude comparison and variable step size MUSIC, which mainly comprises the following steps: obtaining an initial estimated angle through an amplitude comparison algorithm; if the angle is located in a cross-angle domain of a ring antenna, the high-precision characteristic of the amplitude comparison algorithm in the angle domain is utilized to directly take the angle as a final result, so that the direction finding performance of the angle domain is improved; if the angle is not located in the cross-angle domain, the initial estimated result is further utilized to reduce the spectral peak search range of a MUSIC algorithm, and a variable step size mode is adopted to search a spatial spectrum function, so that the direction finding resolution of the MUSIC algorithm is improved, and the calculation complexity is reduced. The application utilizes two direction finding algorithms of amplitude comparison and MUSIC, realizes high-precision direction finding in the cross-angle domain of the ring antenna, shows higher resolution success rate, effectively improves direction finding efficiency, and has important application value in the fields of high-frequency radar sea current detection and short-wave communication.

The application relates to an over-the-horizon chirp spread spectrum communication signal-to-noise ratio estimation method, a system and a storage medium, and relates to the technical field of over-the-horizon communication. The method comprises the following steps: S1, acquiring a received signal in over-the-horizon chirp spread spectrum communication, performing despread and Fourier transform on the received signal to obtain corresponding frequency spectrum data; S2, extracting a useful signal amplitude and a noise signal amplitude from the frequency spectrum data; S3, calculating a log-domain amplitude ratio feature of the received signal by using the useful signal amplitude and the noise signal amplitude; and S4, inputting the log-domain amplitude ratio feature into a pre-trained signal-to-noise ratio estimation model to obtain a signal-to-noise ratio estimation value of the received signal; wherein the pre-trained signal-to-noise ratio estimation model is a piecewise linear regression model trained based on training samples under different signal-to-noise ratio conditions. Compared with the prior art, the application can avoid increasing the calculation overhead of additional discrete Fourier transform, thereby reducing the calculation complexity and accurately calculating the signal-to-noise ratio under different intensity noise environments, and the real-time performance and the estimation accuracy are considered.

The application belongs to the field of piezoelectric driver nonlinear modeling, and particularly discloses a piezoelectric driver creep nonlinear dynamics model and a construction method and system thereof. c (s)=s ‑μ ; wherein s is a Laplace operator; the identification method of the parameter mu includes: constructing input voltage signals with different frequencies omega i , calculating input voltage signal amplitudes U i ; according to the input voltage signals, obtaining output displacement signals of the piezoelectric driver, and simultaneously calculating output displacement signal amplitudes D i ; calculating the amplitude ratio A i of D i and U i ; obtaining a discrete data point set (x i , y i ) which satisfies: according to the linear fitting of the discrete data point set (x i , y i ), determining the slope of the fitted straight line, and determining the parameter mu according to the slope. The model constructed based on the fractional order involves fewer unknown parameters, is easy to identify, and at the same time, the modeling method is not limited by special discrete points in the time / frequency domain, and has higher universality.

This invention relates to a stability measurement method for a constant-temperature hot-wire anemometer based on the identification of equivalent pure delay element parameters, belonging to the field of fluid measurement and automatic control technology. The method disclosed in this invention includes the following steps: S1. Connecting an ultra-low frequency low-pass filter to the closed-loop circuit of the system to form an in-situ open-loop system with a DC closed loop and an AC open loop; S2. Injecting a sweep frequency excitation signal E at the bias circuit. stimu And measure the output response E of the amplifier circuit. a By comparing the amplitude ratio and phase difference of the two, the open-loop frequency response G of the system under actual operating conditions of the hot wire is obtained. open (jω); S3. Using the preset transfer function model G * open (s) Fit the measured frequency response to identify the pure delay element G introduced by non-ideal factors such as circuit distributed parameters and device hysteresis. delay (s), and uses its parameter b to quantify the non-ideal factors of the system. This invention realizes in-situ measurement of system stability, quantifies non-ideal factors into measurable parameters, and provides a reliable basis for system stability analysis and circuit design.

This application relates to the field of wave energy simulation technology and discloses a simulation method and system for dual-mode frequency tuning of oscillating water columns in a double-slit caisson. The method includes: establishing a two-degree-of-freedom dynamic equation system based on the displacements of the water columns in the front and rear cavities, using the slit transmission coefficient as a parameter to obtain the coupling stiffness; substituting the coupling stiffness into the eigenvalue equation to decompose the oscillation modes of the two cavities to obtain the mode transformation matrix and mode amplitude ratio; performing convolution integration on the mode amplitude ratio and the wave power spectrum of the target sea area to obtain the first-order mode weight and second-order mode weight; using a preset target first-order mode weight as the outer convergence target and a preset target natural frequency as the inner convergence constraint to perform a double-layer nested iterative solution on the slit transmission coefficient and the rear cavity volume to obtain the optimal slit width and the optimal rear cavity volume. This application solves the problem of unobservable and undesignable energy contribution ratios of each mode in existing technologies, leading to spectral mismatch.

The invention relates to the technical field of signal processing, in particular to an accurate frequency estimation method combining an amplitude ratio method and an interpolation method, which comprises the following steps of: generating a pulse single-frequency signal with zero filling, and setting a signal frequency value, a pulse width and a total signal length; performing M-point FFT calculation on the received signal to obtain a maximum spectral level position and an adjacent spectral line coefficient, and intercepting a noise segment to estimate noise power; performing coarse frequency estimation through a corrected amplitude ratio method; performing accurate estimation based on a zero-filling improved fractional Fourier coefficient interpolation method; and outputting a final accurate frequency estimation result. According to the method, the problems that the requirement of a fractional Fourier coefficient interpolation method for coarse estimation is high and estimation is inaccurate under the condition that the initial error of a signal frequency domain is large are solved, meanwhile, the problem that an amplitude ratio method does not consider noise power is corrected, and compared with a traditional amplitude ratio method, the accuracy is greatly improved.