197 results about "Frequency meter" patented technology

The invention discloses a self-adaptive fault reflection method and device based on adjustable excitation frequency, and belongs to the technical field of cable fault detection and positioning. The method comprises the following steps: injecting an excitation signal which can be adjusted in a range of 1kHz-10MHz through an adjustable impedance matching network; collecting a reflected signal and calculating an SNR (f) curve; optimizing by adopting a particle swarm optimization algorithm and taking maximization of a signal-to-noise ratio as a target, and determining an optimal excitation frequency; and finally, calculating the fault position and type based on the optimal frequency. The particle swarm optimization algorithm is adopted to perform adaptive optimization on the excitation frequency, and the adjustable impedance matching network is combined to form a closed-loop adaptive detection framework of excitation-acquisition-analysis-optimization-re-excitation, so that the excitation frequency can be automatically adjusted according to a real-time detection result, and the detection accuracy is improved. And the fault detection sensitivity, the positioning precision and the energy efficiency are obviously improved.

The invention relates to the technical field of anti-seismic performance detection, in particular to an anti-seismic performance detection method and system for an assembled steel-wood composite structure, and the method comprises the steps: arranging a multidirectional acoustic emission sensor in a steel-wood structure node area, applying simulated seismic vibration, and synchronously collecting acoustic emission signals; the method comprises the following steps: preprocessing collected acoustic emission signals, dividing the acoustic emission signals into signals corresponding to microcracks and contact slippage, respectively calculating an energy attenuation rate and a phase offset, and constructing a matrix; micro-impact is applied to the steel-wood node through an electromagnetic excitation device, a response signal is collected, resonant frequency is extracted, the drift distance between the resonant frequency and a reference value is calculated, and the severity of interface damage is determined according to the value of the drift distance; the damage correlation index calculation takes the characteristic value of the interface wave propagation characteristic matrix and the resonance frequency drift distance as input, the damage correlation index is calculated through the correlation coefficient, and the damage grade is divided according to the correlation coefficient. And differential characterization of different damage types is realized through the interface wave propagation characteristic matrix.

The invention discloses a fan frequency control method and device, electronic equipment and a computer medium, and belongs to the technical field of automatic incineration. According to the specific scheme, the method comprises the steps of obtaining a parameter sequence value of a control parameter of the automatic combustion control system in a historical period, a current flow value of main steam flow, a flow set value of the main steam flow, a real-time value of steam pocket pressure, a hearth material layer pressure difference value and a control variable sequence value in the historical period; calculating a flow predicted value of the main steam flow; calculating flow deviation; calculating the frequency of an intermediate fan; the steam drum fan frequency is calculated; the flow fan frequency is obtained; calculating a primary frequency given value; and the primary frequency set value is dynamically corrected, and the target primary fan frequency of the primary fan is obtained and adopted to control the primary fan. The response speed of the automatic combustion control system can be effectively improved, so that the control of the frequency of the extension set can be closer to the actual production condition.

The invention relates to a square wave generation method and system based on a DDS signal transmitter, and belongs to the technical field of digital electronic signal synthesis. The method comprises the following steps: calculating a digital analog signal sampling frequency based on a square wave output frequency set by a user, and obtaining a digital fundamental frequency phase signal according to a phase-locked loop precision range; mapping the digital fundamental frequency phase signal into a sinusoidal amplitude signal according to a digital phase accumulation mechanism to obtain a digital-analog conversion clock, binarizing the sinusoidal amplitude signal, and outputting a square wave output period; dividing a square wave output period into a low level region and a high level region according to the precision range of the phase-locked loop, reading a square wave output frequency set by a user through a random storage address, and outputting a non-offset phase-locked square wave; and constructing an error accumulation self-checking architecture to calculate a frequency control word, and when detecting that the frequency control word has a decimal discarding error, recalculating the frequency control word.

The invention relates to the technical field of electronic measurement and sensing, and discloses a capacitance monitoring method and system based on a sweep frequency resonance point, and the method comprises the steps: carrying out the coarse sweeping in an initial frequency range, obtaining an impedance spectrum, and recognizing a coarse resonance interval; carrying out fine scanning in the interval and calculating an accurate resonant frequency by adopting a quadratic interpolation method; calculating a capacitance value in combination with the mapping table; and dynamically adjusting the frequency sweeping window of the next period based on the historical resonant frequency. The system comprises an excitation signal generation unit, an impedance response acquisition unit, a coarse / fine scanning control unit, a resonant frequency calculation unit, a capacitance resolving unit and a dynamic frequency window updating unit, and integrates a temperature compensation and anomaly detection mechanism. Through the two-stage frequency sweeping and self-adaptive frequency window strategy, the monitoring period is shortened to 1 / 5 or below of that of a traditional method while it is guaranteed that the resonant frequency measurement precision is superior to 0.01 Hz, and the real-time performance, stability and environmental adaptability are remarkably improved.

The invention belongs to the technical field of cable insulation material aging detection, and relates to a cable aging degree judgment method based on an impedance spectrum and a related device. The method comprises the steps of obtaining a reflection coefficient curve based on an impedance spectrum curve; obtaining a reflection coefficient real part curve based on the reflection coefficient curve, and extracting a resonant frequency corresponding to a resonant point of the reflection coefficient real part curve; calculating a relative dielectric constant real part of an insulating medium of the cable to be measured under different resonant frequencies; outputting an attenuation constant curve based on the reflection coefficient curve and a cable reflection coefficient amplitude calculation model; extracting a plurality of attenuation constant values of the attenuation constant curve on the resonant frequency; substituting the attenuation constant value and the relative dielectric constant real part into a dielectric loss angle tangent value calculation model to obtain a dielectric loss angle tangent value of the to-be-measured cable under the resonant frequency; and carrying out aging degree judgment based on the dielectric loss angle tangent value. The problem that an existing method is long in time consumption or cannot acquire full-band dielectric information of a cable insulating material is solved.

The application discloses a transformer operation state monitoring and fault early warning method based on state index calculation, relates to the technical field of transformer operation state monitoring, and aims to solve the problem of reduced accuracy of potential fault identification. In the transformer operation process, winding temperature is collected to calculate temperature rise trend and monitor vibration state, vibration frequency is obtained, operation stress coefficient is calculated in combination with the temperature rise trend and the vibration frequency, the electric conductivity of insulation oil in the oil circulation pipeline is detected, the state index is generated by comprehensively considering the electric conductivity and the operation stress coefficient, and the transformer operation state is classified accordingly. When the state is warning, multiple groups of different cooling powers are inputted, the monitoring time is set, the corresponding radiator outlet air temperature is collected, the power change amount and the outlet air temperature difference change amount are calculated after the cooling powers are sorted, the heat dissipation characteristics are comprehensively evaluated, and it is judged whether a fault warning signal is generated, so that early warning of potential faults of the transformer is realized, and operation safety and reliability are improved.

The invention provides a dynamic phase compensation method based on double DDS modules, and belongs to the technical field of digital frequency synthesis. The invention provides the following technical scheme: 1, a dynamic phase inheritance mechanism: through alternate work of double DDS modules, seamlessly transmitting an integer part and a decimal remainder contained in a phase accumulated value of a main DDS to a standby DDS during switching, and combining a shared clock source and a high-speed multiplexer to ensure phase continuity; 2, remainder compensation closed-loop control is carried out, a remainder accumulator is designed to record truncation errors in real time, FTW is dynamically adjusted through a PID algorithm, and long-term frequency error closed-loop suppression is achieved in combination with feedback of an external frequency meter; 3, according to a dual-mode triggering strategy, time period triggering and phase threshold triggering are supported, switching logic is started when a triggering condition (a fixed period or a phase threshold theta th is set) is met, and the phase accumulated value theta 1 (t) and the remainder epsilon 1 of the DDS1 are transmitted to the DDS2. According to the invention, through dynamic phase synchronization and closed-loop compensation, the problems of DDS phase accumulative errors and switching discontinuity are systematically solved.

The invention provides a method for improving PT residual voltage frequency measurement accuracy based on rotation vector characteristics, and relates to the technical field of generator set rotation speed measurement. The method comprises the following steps: acquiring a three-phase voltage alternating current signal through a generator end PT; processing the three-phase voltage signal to obtain projections of a voltage rotation vector on alpha and beta static coordinate axes; frequency characteristics are extracted based on projection and voltage amplitude and can be realized through direct calculation or a phase locking link; performing low-pass filtering on the frequency characteristic direct current quantity; a generator speed is calculated based on the filtered frequency and provided to a governor. According to the method, the limitation that a traditional PT residual voltage method only depends on zero crossing point information is broken through, frequency characteristics are extracted through a complete voltage sequence, alternating current signal filtering distortion is avoided through direct current filtering, high measurement precision and high anti-interference capacity can still be kept under the low-speed working condition, the problems that an existing speed measurement method is insufficient in precision and weak in anti-interference capacity are effectively solved, and the method is suitable for popularization and application. And reliable guarantee is provided for safe and stable operation of a unit.

The invention discloses a hybrid high-precision frequency weighting method and system and electronic equipment, and the method comprises the steps: obtaining an original sound signal, carrying out the analog-to-digital conversion, and carrying out the preprocessing of the sound signal after the analog-to-digital conversion, so as to obtain a signal frequency spectrum; segmenting the signal spectrum, and weighting each segment to obtain a first weighting sound level and a second weighting sound level; superposing the first weighted sound level and the second weighted sound level to determine a total weighted sound level; and performing dynamic error calibration on the total weighted sound level, determining a standard error, and when the standard error is smaller than or equal to a preset error threshold value, outputting the total weighted sound level. According to the invention, a differentiated optimization strategy is adopted, and the attenuation deviation of a traditional digital filter in a low-frequency area is effectively corrected in a low-frequency band; in the middle and high frequency bands, the accuracy is ensured, meanwhile, the occupation of operation resources is remarkably reduced, the signal processing delay time is shortened, and the response requirement of real-time noise monitoring can be met.

A method for adjusting and measuring a photovoltaic power plant including a photovoltaic string having solar panels in series and an inverter to convert a DC voltage generated by the photovoltaic string into an AC voltage, the inverter having a DC-voltage inputs, includes:measuring a frequency of an AC voltage generated by the photovoltaic power plant and computing a frequency variation of the AC voltage with respect to a reference frequency and computing a power variation applied by the photovoltaic power plant based on the frequency variation,selecting a DC-voltage input, being the i-th input, to measure a curve of current vs. voltage of the input, having an initial DC voltage, thencomputing a residual power variation applied by the photovoltaic power plantif the residual power variation is non-zero, distributing it over inputs different from the i-th input,repeating the steps to create different points of the measured curve.

The application provides a modal frequency-based multi-span pipeline discrimination method, which comprises the following steps: S1, calculating a single-span modal frequency f0 of a suspended pipeline A section; S2, calculating a multi-span modal frequency f of the suspended pipeline A section i ; S3, calculating a difference between the single-span modal frequency f0 and the initial multi-span modal frequency f i , and comparing a ratio of the difference to the single-span modal frequency f0 with a predetermined threshold value to determine an initial critical span length ratio; S4, gradually increasing an initial span interval ratio α1 by a predetermined span interval ratio interval γ to obtain a plurality of equally-spaced span interval ratios and critical span length ratios corresponding to each span interval ratio; S5, drawing a multi-span discrimination curve, and discriminating a suspended pipeline section under a working condition of the suspended pipeline A section based on the multi-span discrimination curve. The method judges the influence degree between spans according to the change of the pipeline modal frequency under different span interval ratios and span length ratios, and improves the discrimination accuracy.

The application discloses a brake method and system of an automatic portal crane, and the method comprises the following steps: setting a target position of a grab bucket when braking is needed; and cyclically executing the following steps a to e until a difference between an actual position of the grab bucket and a stopping position is less than or equal to a threshold value, and outputting a frequency converter shutdown instruction and a brake starting instruction: a. collecting a real-time frequency of the frequency converter; b. calculating the actual position of the grab bucket; c. calculating a theoretical stopping distance under a current real-time frequency; d. compensating the theoretical stopping distance by considering a load; and e. calculating the stopping position based on the target position of the grab bucket and the compensated stopping distance. The application solves a long-existing problem of 'incompatibility between speed and accuracy' in the field of crane positioning by means of a trinity of non-linear modeling, dynamic calculation and data driving, and provides high-efficiency automatic operation for port automation.

The invention provides a test method and platform for a target capture square wave signal frequency calculation module. The method comprises the following steps: S1, determining a plurality of target capture square wave signal waveform templates which correspond to a tested module and meet preset test requirements; s2, generating a plurality of target capture square wave signals which respectively correspond to the plurality of target capture square wave signal waveform templates, meet preset test requirements and are adjustable in single period; s3, selecting a target capture square wave signal and inputting the target capture square wave signal into the tested module; s4, executing the tested module to obtain a target capture square wave signal frequency measured value; s5, judging whether the measured frequency value of the target capture square wave signal is consistent with the expected frequency value of the target capture square wave signal or not; the target capture square wave signal frequency expected value is calculated based on a target capture square wave signal input into the tested module; and S6, under the condition of consistency, determining that the test result is passed. According to the scheme, the function test, the boundary test and the like of the target capture square wave signal frequency calculation module can be more accurately carried out.

A built-in vibrator control system of a low-voltage electronic variable frequency motor belongs to the technical field of engineering machinery. According to the technical scheme, the control system is composed of four vibrators with built-in motors, a machine frame, a frequency conversion control cabinet, a grounding wire and a low-voltage electronic frequency converter. A cable of the vibrator with the built-in motor is inserted into the frequency conversion control cabinet through an industrial plug and is tightly and reliably fixed with the rack; a system circuit is composed of an air switch, a voltmeter, an ampere meter, a frequency meter, an indicating lamp, a thermal relay, an intermediate relay, a cooling fan, a low-voltage electronic frequency converter and a matched remote control device. A circuit of the frequency conversion control cabinet is divided into a manual unit and a remote control unit which can be switched to start, operate and reset. The system has the advantages of overcoming the defects of an existing system, guaranteeing vibration compaction quality, achieving mechanization and intellectualization of concrete compaction construction, and being high in operation efficiency, good in compaction effect, novel in design, reasonable in structure, comfortable to operate, easy and convenient to maintain, safe and reliable.

The embodiment of the invention discloses a method for constructing a pile foundation scouring depth prediction model based on multi-modal parameters. The method comprises the steps that acceleration and scouring depth time history data of a pile foundation in the scouring process are obtained; for each scouring depth, the following operations are executed: according to the acceleration time history data, the frequencies of the pile foundation before and after scouring and the vibration modes of a plurality of measuring points on the pile foundation are identified; calculating a frequency change rate according to the frequencies before and after washing; calculating modal curvature and diagonal flexibility of each measuring point according to the vibration mode of each measuring point; performing principal component analysis on the modal curvature and the diagonal flexibility of each measuring point, retaining the principal components of the first plurality of levels as curvature features, and forming a feature vector with the frequency change rate; and training an ANFIS model by using each scouring depth and the corresponding feature vector, wherein the trained model is used for automatically predicting the corresponding scouring depth according to one feature vector. According to the embodiment of the invention, through multi-modal parameters, the uncertainty influence is reduced, and the prediction reliability and accuracy are improved.

The invention relates to a stator core fault standard local excitation temperature rise measurement method and system, computer equipment, a storage medium and a computer program product. The method is applied to a temperature rise measurement system, and comprises the following steps: after a standard local excitation frequency is applied to a fault tooth part, calculating first flux density power according to the reading of a first power analyzer and the reading of a second power analyzer; calculating standard flux density power based on the first flux density power, the standard local excitation frequency and the target local excitation frequency; after the target local excitation frequency is applied to the fault tooth part, second flux density power is calculated according to the reading of the first power analyzer and the reading of the second power analyzer; and when the second flux density power is equal to the standard flux density power, carrying out temperature rise measurement for preset time to obtain the standard local excitation temperature rise of the fault tooth part. By adopting the method, the standard local excitation temperature rise of the stator core fault can be measured under the condition that the standard excitation frequency is changed.

This invention discloses an additional frequency regulation control method for a multi-terminal flexible DC system based on multiple agents, comprising the following steps: configuring an Agent for each battery swapping station participating in frequency regulation control in the multi-terminal flexible DC system; adjacent Agents being connected via a communication network; each Agent including a weighted frequency calculation module and a frequency droop control module; the weighted frequency calculation module calculating the system weighted frequency using a discrete consensus algorithm based on information from the local and adjacent Agents. f ref The Agent information includes: the frequency droop control coefficient of the converter station. K f and weighted frequency f K Where, f is the frequency of the AC system connected to the converter station; the frequency droop control module is based on the system weighted frequency. f ref Calculate the additional frequency regulation power of the converter station P f The frequency droop control module will P f Superimposed on the converter station power setpoint P set The invention changes the output power of the converter station to participate in system frequency regulation. It has the advantages of low communication burden, high reliability, easy implementation of decentralized control, and easy expansion.

The invention discloses a rotating speed measuring device and method. The device converts an echo based on a time domain into a power spectrum based on a frequency domain, wherein the echo corresponds to a reference acoustic wave having a reference frequency emitted by the device. The device retrieves a sidelobe frequency corresponding to the reference frequency in the power spectrum, where the sidelobe frequency has a relative peak with respect to a plurality of adjacent frequencies. Based on the sidelobe frequency and the reference frequency, the device calculates a rotating speed of an object to be measured during operation.

The application discloses a kind of pseudo-random code control's multi-parameter composite modulation short-range detector high-precision ranging velocity measurement method, comprising: echo signal and local oscillator mixing, obtain the intermediate frequency signal containing Doppler signal and difference frequency signal by low-pass filter, filter out high-frequency component;The input signal is converted into complex signal first after FFT, determine the refinement interval, then utilize spectrum refinement algorithm to accurately measure difference frequency signal frequency, calculate target distance by difference frequency frequency;Difference frequency signal is under-sampled to extract Doppler frequency, and the frequency of Doppler signal is measured by FFT, and the target speed is calculated by Doppler frequency.The application is from the establishment of composite system difference frequency signal model, using CZT conversion and time domain under-sampling technique to process difference frequency signal, finally extract difference frequency and Doppler signal frequency.

This application relates to the field of artificial intelligence technology, and in particular to a frequency regulation system, method, and storage medium for thermal power units. It includes: an end-side processing device comprising an end-side acquisition layer and an edge computing layer. The end-side acquisition layer acquires the operating data of the thermal power unit and the frequency of the power grid. The edge computing layer calculates the frequency deviation based on the actual frequency and target frequency of the power grid. It deploys a lightweight intelligent agent that outputs a load adjustment amount for the thermal power unit based on at least one of the operating data, frequency, and frequency deviation. This load adjustment amount is then sent to the control system of the thermal power unit. The control system generates a target frequency regulation command based on the load adjustment amount and controls the thermal power unit to perform a frequency regulation action based on the target frequency regulation command. A cloud-based system is used to train the intelligent agent using a training module and distribute the lightweight intelligent agent to the end-side processing device. This solves the problems of difficulty in meeting the low-latency requirements of frequency regulation and poor real-time performance in related technologies.

The application provides a peak value orientation-based vibration characteristic frequency calculation method and device. The peak value orientation-based vibration characteristic frequency calculation method comprises: obtaining a target frequency spectrum corresponding to a device acceleration signal; determining a scanning range on the target frequency spectrum according to a characteristic frequency range of a preset component in the device; calculating characteristic frequencies of each component corresponding to each position in the scanning range according to frequencies corresponding to the positions; determining a peak value number of each position according to the characteristic frequencies of each component corresponding to the positions; and determining a target characteristic frequency of each component according to a position with the most peak values in the scanning range. Through the application, the characteristic frequency can be determined based on the peak value attribute of the characteristic frequency, the operation can be simplified, the calculation accuracy of the characteristic frequency can be improved, the fault recognition rate can be improved, and the fault characteristic frequency can be found early.

The present application relates to a kind of sound barrier noise reduction structure and its design method, comprising: the high-frequency valley of high-frequency noise of the measured noise spectrum is determined as the valley frequency of the high-frequency sound insulation amount of the resonant unit, the low-frequency peak of low-frequency noise is determined as the peak frequency of the low-frequency sound insulation amount of the composite waveguide layer, according to the number of low-frequency peak determines the number of Helmholtz cavity;According to valley frequency, obtain the thickness of micro-perforated plate layer, the diameter of small hole on micro-perforated plate layer, the thickness of hollow cavity layer and its cross-sectional size parameter relationship formula, so as to optimize the selection of relevant parameters;According to each peak frequency, respectively calculate and obtain the volume of corresponding Helmholtz cavity, and the effective area, cross-sectional length relationship of its corresponding throat pipe, so as to optimize the selection of effective area.The structure designed by resonance system controls high-frequency noise, utilizes the Helmholtz cavity of composite waveguide layer to control low-frequency noise, realizes selective sound insulation in large frequency range.

This application discloses a high-precision microwave frequency measurement method and system based on continuous-time crystal phase transitions, belonging to the field of quantum sensing technology. This method utilizes the characteristic of the Rydberg atom system at the critical point of a continuous-time crystal phase transition where the response slope of the detected light transmission signal to the microwave frequency is significantly enhanced, breaking through the resolution limit of traditional linear responses. The system includes a quantum sensing unit, an optical excitation and detection module, a microwave modulation and scanning module, an auxiliary radio frequency field module, and a signal processing and control center. By precisely adjusting the parameters, the system is driven to the vicinity of the critical point, the critical frequency is identified, and its high response slope is used to achieve precise frequency measurement. This invention employs a two-stage measurement process, balancing wide dynamic range and high precision, and can be flexibly tuned to adapt to different frequency bands, possessing broad application prospects, especially in microwave communication, frequency metrology, and other fields with significant technical value.

A leaf tip timing signal spectrum reconstruction method based on delay sampling comprises the steps that leaf tip timing sensors collect leaf data, discrete Fourier transform is carried out on vibration displacement data, collected by each sensor, of each leaf, and an aliasing spectrum is obtained; according to a given amplitude threshold value, determining a to-be-reconstructed spectral clue index; spectral line aliasing conflict detection is carried out according to a given spectrum coefficient difference threshold value; determining a frequency spectrum folding frequency M according to the signal highest frequency prior, and further determining a possible target frequency corresponding to each spectral line to be reconstructed; calculating the least square solution of the real spectrum coefficient according to the aliasing spectrum coefficient and the possible target frequency, and calculating an estimation error; all possible target frequencies are traversed, the possible target frequency with the minimum estimation error serves as the final target frequency, and the least square solution corresponding to the possible target frequency serves as the real spectrum coefficient.

The application provides a small hydropower frequency prediction method based on weighted distribution; the same prediction interval and standard interval values are set; the frequency of the prediction interval after the current time point is calculated from the reference frequency of the standard interval of the small hydropower operation record; the duration of the small hydropower operation is divided into n standard intervals A; then the weighted value K corresponding to each standard interval A is calculated; and then the average frequency E of the prediction interval is calculated. The value range of the value n is set; the minimum value of the value n is 2, because the values of the standard interval A and the prediction interval C are the same; the prediction frequency of the small hydropower operation in the prediction interval C is calculated from the reference frequency of the small hydropower operation in more than two standard intervals A; if n is not an integer, n is rounded down to an integer, and the complete standard interval is used for calculation; the accuracy is high; the maximum value of the value n is set as 10, the result reliability is improved, and the calculation amount is reduced.

The application relates to a reflective optical fiber turbine oxygen supply flow detection and avionics conversion system and method, and belongs to the technical field of airborne oxygen supply detection and avionics bus. The system comprises the following: an optical fiber turbine oxygen supply flow detection unit, which is used for rectifying the oxygen supply airflow to be detected and then conveying the airflow to a turbine to drive the turbine to rotate, and collecting a periodic light pulse signal generated by the rotation of the turbine; a signal processing and conversion unit, which is used for converting the periodic light pulse signal into a voltage pulse signal and performing hierarchical processing, and obtaining a calibrated pulse signal after waveform shaping and proportional scaling; a bus conversion unit, which is used for measuring the frequency of the calibrated pulse signal, calculating an instantaneous oxygen supply flow value and converting the value into an ARINC429 protocol data frame; and a driving differential output circuit, which is used for converting the ARINC429 protocol data frame into a differential electrical signal of bipolar return-to-zero code and outputting the signal to an avionics bus network. The application can meet the urgent needs of high-performance aircraft for intelligentization and high reliability of an oxygen supply system.

A vehicle charging device according to the present embodiment comprises: an amplitude detection unit that detects a magnitude of a grid voltage being inputted to the vehicle charging device; a frequency detection unit that detects a frequency of the grid voltage; a PLL (Phase Locked Loop) unit that monitors a phase of the grid voltage; and a gain selection unit that inputs a coefficient calculated using the magnitude and frequency of the grid voltage to the PLL unit, wherein the amplitude detection unit and the frequency detection unit detect a plurality of points at which the state of the grid voltage changes.

The invention relates to the technical field of construction site safety monitoring and Internet of Things, and discloses an automatic alarm safety helmet which comprises a safety helmet body, an integrated module and a lower jaw belt are detachably installed on the safety helmet body, and a resistance sensor and a reference capacitor assembly which are used for making contact with the skin of a wearer are packaged in the lower jaw belt. The resistance inductor and the reference capacitor assembly are connected to form a passive network of an RC oscillation detection loop, and a chip, a WiFi module, a buzzer, a power supply, a signal excitation source and a frequency meter are arranged in the integrated module. According to the invention, the reference capacitor assembly is implanted in the mandibular belt and the RC oscillation detection loop is constructed, and the wearing judgment is carried out by using the characteristic that the oscillation frequency is changed after the human skin resistor is connected to the circuit, so that the problem of cheating caused by the pressing of a heavy object or the short circuit of a lead in the prior art is effectively solved, and the monitoring accuracy and the anti-cheating capability are improved.

The application provides a sparse auxiliary variational nonlinear signal decomposition method and system, comprising: determining the number of sub-signals of an original signal and initial instantaneous frequencies of each sub-signal, calculating a preliminary demodulation signal of each sub-signal, calculating an optimized demodulation signal of each sub-signal, calculating an initial instantaneous frequency increment of each sub-signal, calculating an optimized instantaneous frequency increment of each sub-signal, calculating an initial optimized instantaneous frequency of each sub-signal, calculating a final optimized instantaneous frequency of each sub-signal, reconstructing each sub-signal x according to the optimized demodulation signal and the final optimized instantaneous frequency of each sub-signal i ; setting a termination iteration threshold value ε, and judging whether the reconstructed sub-signal satisfies the set termination iteration threshold value; if not, repeating the execution, and if yes, completing the decomposition of the original signal. The application realizes the decomposition of a complex multi-component signal, accurately estimates the instantaneous frequency of each sub-signal and reconstructs each sub-signal.