8 results about "Power bandwidth" patented technology

This invention belongs to the field of bridge quality inspection technology, specifically a method for evaluating the quality of box girders based on the MH wavelet average evolved power spectrum. The method includes: selecting a qualified standard beam, deploying vibration sensors to collect vertical acceleration time-history signals; preprocessing the signals by performing wavelet transform, calculating the squared modulus of the wavelet coefficients and normalizing them to obtain a three-dimensional evolved power spectrum, and then averaging the time dimension to obtain the average evolved power spectrum; extracting three characteristic parameters—frequency at maximum power, half-power bandwidth, and skewness—using the standard beam spectrum as a benchmark; repeating the above steps on the beam to be evaluated, comparing the deviations of the characteristic parameters, and combining a grading threshold and a differentiated review process to determine the quality, and statistically analyzing the batch data dispersion to provide feedback on the stability of the beam manufacturing process. This invention achieves non-destructive, batch, and accurate evaluation of box girder quality, and can effectively identify hidden defects such as insufficient elastic modulus of concrete and prestress loss.

The invention discloses a pressure vessel local defect detection method and system based on sound wave and micro-vibration spectrum fusion, and relates to the field of mechanical vibration or sound wave measurement. The system comprises an intelligent excitation hammer with a built-in force sensor, a composite sound and vibration acquisition unit and a data processing terminal, wherein the composite sound and vibration acquisition unit and the data processing terminal are coaxially designed. The method comprises the steps that a force sensor signal is used as a trigger source, and impact force, air sound waves and shell vibration signals are synchronously collected; calculating a sound-force transfer function to realize input energy normalization and eliminate manual knocking force difference; constructing an adaptive filter by using the sound-vibration coherence function, and performing weighting processing on the acoustic spectrum to filter environmental background noise to generate an enhanced structure sound spectrum; and finally, based on the characteristic frequency offset and the half-power bandwidth damping ratio, constructing a damage index (DI) to carry out quantitative judgment on defects. The method solves the problems that traditional acoustic detection is poor in noise immunity and cannot be quantified, and high signal-to-noise ratio detection on defects such as corrosion and delamination of the pressure vessel in a strong noise environment is achieved.

This invention belongs to the field of thin-walled component working modal parameter measurement technology, and discloses a method and system for omnidirectional working modal testing of thin-walled components based on binocular vision intelligent collaborative tracking. The method includes: dimensionality reduction of measurement point data based on principal component analysis; denoising and outlier processing of the data; singular value decomposition based on the power spectral density matrix to generate a singular value spectrum; automatic identification of candidate modal frequencies in the EFDD singular value spectrum using a peak search algorithm, and automatic estimation of their half-power bandwidth to determine the fine analysis frequency band of SSI-DATA; use of an integrated machine learning clustering algorithm for automated interpretation of the stability graph; and addition of a nonlinear diagnosis and identification module for nonlinear detection. This invention constructs a more efficient, intelligent, accurate, and capable modern solution for thin-walled component working modal parameter identification in complex real-world environments, fully leveraging the enormous potential of machine vision non-contact measurement.

The present application provides a data transmission method, a communication device, and a storage medium. The data transmission method comprises: performing an interpolation operation on a first data sequence, so as to obtain a second data sequence (S110); performing a filtering operation on the second data sequence, so as to generate a time-domain signal (S120); and transmitting the time-domain signal, wherein the half-power bandwidth of a frequency-domain filtering function of the filtering operation is equal to 1 / (N+1) times the sampling rate of the second data sequence, N being the number of pieces of data interpolated between every two adjacent elements in the first data sequence (S130).

The invention relates to the technical field of hybrid direct-current power transmission systems, in particular to a harmonic detection method and device for a hybrid direct-current power transmission system. The method comprises the following steps: determining segmentation duration based on a dominant frequency extracted from a component, and dividing the component into signal segments according to the segmentation duration; determining a waveform consistency index according to amplitude fluctuation similarity between adjacent signal segments; determining an initial harmonic confidence coefficient according to the waveform consistency index, the amplitude of the main frequency and the half-power bandwidth; determining the dynamic correlation degree of the component and the fundamental wave signal according to the active power data of the system and the amplitude change characteristics of the component and the fundamental wave signal; determining integer frequency multiplication integrating degree according to the deviation degree of the dominant frequency of the component relative to the fundamental wave frequency; according to the dynamic correlation degree and the integer frequency multiplication integrating degree, determining the comprehensive harmonic confidence degree of the component; and judging whether the component is a harmonic component according to the initial harmonic confidence and the comprehensive harmonic confidence, and analyzing and outputting the electrical characteristic parameters of the harmonic component, thereby improving the accuracy of harmonic identification.

The application discloses a road construction quality detection method based on an intelligent sensor, which comprises the following steps: step one, collecting drum vibration acceleration signals and performing sliding time window segmentation to form a vibration signal segment sequence; step two, performing direct current removal on the vibration signal segment sequence and calculating a frequency spectrum amplitude distribution to screen effective vibration signal segments; step three, extracting a main peak coupling frequency, a half-power bandwidth, a harmonic energy ratio and a self-correlation delay parameter to construct a characteristic vector; step four, normalizing the characteristic vector and calculating a vector angle to obtain a characteristic angle distance mapping value; step five, constructing a characteristic spectrum representation matrix by using an improved Gegenbauer polynomial and a fractional order modulation; step six, performing a fractional order spectrum operator mapping calculation to obtain a construction quality calculation value; and step seven, performing section determination according to a quality threshold value. The application realizes stable detection and evaluation of road construction quality.

The present application relates to the technical field of hybrid DC power transmission system, and particularly relates to a harmonic detection method and device of a hybrid DC power transmission system. The method determines a segment duration based on a main frequency extracted from a component, and divides the component into signal segments according to the segment duration; determines a waveform consistency index according to the amplitude fluctuation similarity between adjacent signal segments; determines an initial harmonic confidence according to the waveform consistency index, the amplitude of the main frequency and the half-power bandwidth; determines a dynamic correlation degree between the component and the fundamental signal according to the system active power data and the amplitude variation characteristics of the component and the fundamental signal; determines an integer frequency coincidence degree according to the deviation degree of the main frequency of the component relative to the fundamental frequency; determines a comprehensive harmonic confidence of the component according to the dynamic correlation degree and the integer frequency coincidence degree; determines whether the component is a harmonic component according to the initial harmonic confidence and the comprehensive harmonic confidence, analyzes and outputs the electrical characteristic parameters of the harmonic component, thereby improving the accuracy of harmonic identification.

The invention relates to the technical field of low-orbit satellite communication Doppler frequency shift compensation, and provides a low-orbit satellite communication Doppler frequency shift estimation comprehensive compensation method and a low-orbit satellite communication Doppler frequency shift estimation comprehensive compensation system. Calculating a half-power bandwidth of the satellite communication signal, an autocorrelation coefficient under a preset time delay and a maximum peak phase difference, calculating a carrier distortion coefficient of an acquisition moment corresponding to the satellite communication signal, and constructing a carrier distortion sequence of the acquisition moment; according to the first-order differential value of the denoised carrier distortion sequence at the collection moment and the Doppler frequency shift data at the adjacent collection moment, calculating the look-ahead tracking complexity at the collection moment; and in combination with Doppler frequency shift data, calculating an interference frequency correction value at an acquisition moment, and realizing Doppler frequency shift compensation of low-orbit satellite communication according to the interference frequency correction value. According to the invention, the accuracy of frequency shift compensation can be improved.