18 results about "Periodogram" patented technology

The invention relates to the technical field of vibration monitoring, and discloses a steam turbine cold end fault diagnosis method and system based on a fusion time sequence convolutional network, and the method comprises the steps: eliminating the frequency spectrum drift caused by the rotation speed fluctuation through band-limited filtering and order domain resampling, and automatically extracting the specific low-frequency modulation component of a cold end through the envelope square and a periodogram, and finally, the asymmetric dynamic response characteristics of the rotor system are quantified by third-order spectrum phase bias, and the phase change rule is adaptively learned by the pre-trained convolutional network. According to the method, the problem that traditional amplitude spectrum analysis is high in misjudgment rate under the strong noise, variable speed and unsteady environment is effectively solved, the fault features show higher stability and distinguishability in the phase domain, and therefore high-robustness and high-precision automatic diagnosis of the turbine cold end rotor faults is achieved.

A method and apparatus for radar sensing in a disaggregated radio access network. The apparatus includes interface circuitry to receive data from a radio unit and processing circuitry to perform radar sensing processing on the received data to determine at least one of range, velocity, or direction of at least one target in an environment. The radar sensing processing includes range processing, Doppler processing, two-dimensional range-Doppler periodogram processing, constant false alarm rate (CFAR) detection processing, angular resolution processing, and post processing. The data received from the radio unit is beam domain data obtained by receive beamforming, and the processing circuitry is configured to perform decompression processing for converting the beam domain data to antenna domain data and perform at least the angular resolution processing and the post processing on the antenna domain data. The processing circuitry may perform the decompression processing after the CFAR detection processing.

This invention discloses a method for verifying and confirming numerical prediction thrust spectrum results of propellers, belonging to the field of computational fluid dynamics (CFD) result verification and confirmation. While maintaining consistency between the physical model and boundary conditions, this invention encrypts the CFD calculation settings with joint discrete parameters and quantitatively characterizes simulation errors and uncertainties based on Richardson extrapolation. This invention employs the Lomb-Scargle periodogram method to directly process non-uniformly sampled data, avoiding spectral distortion caused by resampling interpolation and improving the accuracy of spectrum estimation. This invention automatically selects the optimal AR model order through information criteria, models colored noise backgrounds in actual engineering, and achieves adaptive noise modeling. This invention simultaneously evaluates the statistical significance of the global maximum peak value and each expected harmonic frequency in a single Monte Carlo simulation cycle. This invention uses a block bootstrap method to calculate the frequency band power confidence interval, maintaining the local correlation of the time series and achieving reliable confidence interval quantification.

The invention discloses a wireless coherent full-duplex double-sided bidirectional ranging method and system. The method comprises the following steps: setting two wireless incoherent radars to be respectively positioned on two sides to be subjected to ranging; in a full duplex transmission mode between the two radars, the two radars respectively emit linear frequency modulation continuous wave signals and receive signals from the other radar; extracting a synthesized beat frequency signal from the received signal; determining the maximum value of the periodogram, and estimating the distance of the line-of-sight path from the beat frequency signal; respectively calculating phase estimation values of up and down frequency modulation according to the up and down frequency modulation slopes, and calculating a displacement step estimation value through the phase estimation values of the up and down frequency modulation; and performing periodic error modeling and correction on the plurality of displacement step length estimation values to obtain an absolute position estimation value. According to the method, beat frequency estimation and coherent phase tracking are combined, high-precision transmission can still be achieved in a complex and severe environment, beat frequency estimation is adopted for distance measurement, and the absolute position is measured with millimeter-level precision.

This invention discloses a respiratory rate extraction method based on multimodal pulse wave feature fusion, comprising: 1. filtering and windowing the pulse wave signal; 2. extracting four types of non-uniform sampling feature sequences from each signal window: respiratory induction amplitude variation, respiratory induction intensity variation, respiratory induction frequency variation, and respiratory induction continuous contraction difference variation; 3. converting each sequence to the frequency domain using a Lomb-Scargle periodogram, extracting the corresponding respiratory rate estimate, and calculating signal quality indices including main peak significance, in-band signal-to-noise ratio, and harmonic energy ratio; 4. constructing a four-dimensional feature vector based on the respiratory rate and quality indices corresponding to each feature, obtaining a preliminary frequency estimate through comprehensive confidence weighting, consensus cluster fusion, and harmonic correction, and then outputting the final respiratory rate after time-series smoothing. This invention can achieve complementary fusion of multiple features, thereby effectively improving the robustness and accuracy of respiratory rate estimation.

The invention discloses a river ecological water demand multi-scale dynamic evaluation method considering environmental changes. Comprising the following steps: acquiring historical runoff data of a target river reach, and taking a sequence minimum value as low water runoff of the period; periodically identifying the low water runoff time sequence, performing correlation analysis, drawing a periodic diagram, selecting three periods with the highest correlation as main periods, and constructing a time periodic function; constructing a candidate model and estimating parameters; selecting an optimal model to calculate the dynamic ecological flow, and calculating the traditional ecological flow based on a time-invariant model; performing high-low judgment on the investigation period to obtain a high-low criterion, and combining the high-low criterion, the dynamic ecological flow and the traditional ecological flow to generate a recommendation threshold value; and respectively executing each step on a plurality of scales of year, season and month, and outputting a recommendation threshold value of the corresponding scale. A dynamic model is combined with a traditional fixed value to generate a recommendation threshold value, so that the scientific frontier of the method is ensured, and the feasibility and robustness of management decision are enhanced.

The invention discloses an underwater acoustic quaternary frequency shift keying signal carrier frequency estimation method, which comprises the following steps of: performing periodogram method power spectrum estimation on an underwater acoustic signal which is identified as quaternary frequency shift keying, and finding four frequency points with the strongest energy; the first frequency point, the second frequency point, the third frequency point and the fourth frequency point are sorted from small to large, and the difference values of the adjacent frequency points after sorting are calculated as the first difference value, the second difference value and the third difference value. The underwater acoustic quaternary frequency shift keying signal carrier frequency estimation method provided by the invention is established on the basis that an identified communication signal is a quaternary frequency shift keying signal, so that the carrier frequency estimation method provided by the invention only aims at the condition that the power spectrum frequency does not decline or declines by one in a periodogram method; when two or more frequencies are lost, the signal can be directly identified as other signals and cannot enter the process, so that the effects of minimum calculation amount, simplest implementation and highest estimation precision are achieved.

The application discloses a moving target echo interference suppression method of a full-duplex sensing integrated system, and comprises the following steps: S1. signal transmission and reception are performed to suppress static self-interference signals; S2. OFDM radar processing based on a periodogram is performed on the signals after self-interference suppression to obtain an initial ambiguity function, and delay / Doppler information of moving target echoes is extracted; S3. targets are numbered according to target echo power, and a termination threshold is set; S4. the absolute value of the ambiguity function is compared with the termination threshold; S5. reconstruction of the first target echo is performed to obtain the first iteration signal; S6. the ambiguity function of the first iteration is obtained; S7. steps S4-S6 are repeatedly executed until the maximum value of the absolute value of the ambiguity function is smaller than the termination threshold, and finally, the output signal is obtained. The application enables the receiver to suppress static self-interference of the same frequency at the same time, and to decouple moving target echo signals and uplink communication signals of the same frequency at the same time, so as to extract sensing information and uplink communication information.

A system for measuring long-distance respiration rate is provided. The system includes a processing unit configured to receive and normalized a sensor output signal. The processing unit is further configured to compute a series of four Discrete Prolate Spheroid window functions. For each of the series of four Discrete Prolate Spheroid window functions, the processing unit is configured to (1) multiply the normalized sensor output signal by the Discrete Prolate Spheroid window function to produce a windowed output signal, and (2) compute a Lomb-Scargle periodogram based on the windowed output signal. The processing unit is further configured to compute a weighted average of the Lomb-Scargle periodograms to produce an averaged periodogram. The processing unit is further configured to compute a frequency corresponding to a peak estimated spectral density on the averaged periodogram. The processing unit is further configured to output breaths per minute data based on the frequency.

The invention discloses an image transmission signal detection method and device for multiple unmanned aerial vehicles, equipment and a medium, and relates to the technical field of wireless radio frequency signal detection, and the method comprises the steps: carrying out the power spectrum density estimation of radio frequency signals of multiple unmanned aerial vehicles through a Weili improved periodogram method, and obtaining a power spectrum density sequence; symmetrical moving average smoothing and morphological filtering are carried out on the frequency spectrum sequence to obtain a preprocessed frequency spectrum sequence; performing local and global noise estimation according to the noise candidate set to obtain an initial noise threshold; adjusting the initial noise threshold value according to the signal intensity quantization factor to obtain a self-adaptive detection threshold value; pre-processing an energy abrupt change boundary of the spectrum sequence through spectrum gradient positioning and generating a signal mask; and finally, aggregating and screening the to-be-clustered frequency point set marked by the signal mask by using DBSCAN clustering to obtain an image transmission signal detection result. According to the invention, the image transmission signal of the unmanned aerial vehicle can be accurately extracted in a complex electromagnetic environment in which multiple unmanned aerial vehicles coexist.

This invention discloses a meteorological signal spectral moment estimation method based on B-ELM. The method includes the following steps: acquiring meteorological pulse data; converting the meteorological pulse data into a meteorological power spectrum using the average corrected periodogram method; using the meteorological power spectrum as the input of the network training samples and the spectral moments as the output of the network training samples to construct the training samples; randomly setting the parameters of the hidden nodes, determining the number of input layer nodes and the number of output layer nodes, and selecting the activation function; constructing a prediction model based on the B-ELM algorithm to obtain the optimal meteorological signal radial velocity and spectral width prediction model; substituting the training samples, the set number of input layer nodes, and the number of output layer nodes into the obtained optimal meteorological signal radial velocity and spectral width prediction model to obtain the radial velocity and spectral width of the meteorological signal. This method has a fast convergence speed, small error, improves the accuracy of meteorological signal spectral moment estimation, and has low computational complexity, which is beneficial for engineering implementation.

A method for electro-acoustic detection of a leak in a pipe conveying a fluid, implemented by a portable device and includes: a step of acquiring a sound signal emitted by the pipe by means of a microphone; a step of processing the signal in real-time with a frequency analysis of the signal by means of a periodogram and extracting features of the signal, including the entropy, a damage-sensitive feature referred to as DSF and a centered frequency corresponding to the barycenter of the periodogram; a step of applying a Kalman filter to estimate residuals; a step of principal component analysis allowing modeling a normal signal of the pipe and of detecting any leak by comparing the signal observed in the normal signal; and an alert and / or notification step in case of detection of a leak.

The invention discloses a real-time anxiety level assessment method and system based on electroencephalogram signals, and belongs to the technical field of biological information processing and psychological health, the method comprises the following steps: continuously collecting original electroencephalogram signals through an EEG electrode, and completing preprocessing through overlapped sliding time window segmentation, Butterworth band-pass filtering and power frequency notch filtering; extracting relative alpha power, relative beta power, relative theta power and beta / alpha power ratio by adopting a Weili average periodogram method to construct feature vectors; the matching system comprises four core modules, namely a data acquisition and preprocessing module, a feature extraction and baseline calibration module, a time sequence analysis and PAI generation module and a biological feedback and data management module. According to the method, individualized accurate evaluation of the anxiety level is realized, the anti-interference capability and the evaluation stability are improved, a'perception-action 'closed loop is constructed, and the method is suitable for scenes such as health management and psychological monitoring.

The application discloses a high-precision velocity measurement method for an FSK radar and a computer readable medium. The method comprises the following steps: sampling a beat frequency signal obtained by mixing a target-reflected echo signal received by the FSK radar with a transmission signal of the FSK radar, to obtain two discrete beat frequency signals with different frequencies; performing fast Fourier transform on the two discrete beat frequency signals, to obtain FFT spectrums of the two discrete beat frequency signals, and taking the frequencies of the spectrum peak positions of the two FFT spectrums as coarse estimation frequencies; taking a range of adjacent spectrum lines on both sides of the coarse estimation frequencies as a reference interval, calculating a periodogram according to the reference interval, and taking a frequency corresponding to a maximum value of the periodogram as a final fine estimation frequency; and calculating a velocity of the target based on the fine estimation frequency. The application can more accurately obtain a specific value of a required frequency, thereby improving the velocity measurement precision of the FSK radar. Compared with a CZT algorithm, the application can greatly reduce an operation amount, and is thus better applied to engineering.

An apparatus including a memory and a processor configured to: obtain a range-Doppler periodogram of received sensing signals, wherein the range-Doppler periodogram is representative of one or more targets within a Doppler span; estimate a range-Doppler coordinate outside the Doppler span for the one or more targets; and selectively process a range-Doppler spectrum of the received sensing signals for the range-Doppler coordinate within a Doppler interval smaller than the Doppler span.

This invention discloses a personalized binaural beat music generation method based on quantitative analysis of EEG frequency bands. This method automatically parses eight mainstream EEG data formats and standardizes the data through adaptive preprocessing. It uses the Welch periodogram method to calculate the power spectrum of five frequency bands, extracts key clinical indicators, and outputs a quantitative state score. Based on the EEG state, it intelligently recommends or allows manual selection of target beat frequencies, embedding the binaural beats into user-selected background audio using AM double-sideband modulation technology. A quantitative verification step for the modulation effect is introduced to ensure the effectiveness of neural feedback. This invention achieves full-process integration of EEG analysis, personalized recommendation, audio synthesis, and playback control, providing a scientific, convenient, and quantifiable technical solution for mood regulation, concentration improvement, and sleep enhancement.

An apparatus including a memory and a processor configured to: obtain a range-Doppler periodogram of received sensing signals, wherein the range-Doppler periodogram is representative of one or more targets within a Doppler span; estimate a range-Doppler coordinate outside the Doppler span for the one or more targets; and selectively process a range-Doppler spectrum of the received sensing signals for the range-Doppler coordinate within a Doppler interval smaller than the Doppler span.

The application discloses a kind of based on random medium model seismic wave tunnel geological prediction method and system, belong to tunnel construction seismic wave method advanced geological prediction technical field.The application is by being arranged in tunnel face line of measurement collection original seismic record, using autocorrelation method extraction seismic wavelet and calculating its power spectrum;Setting sliding window is partitioned to seismic record, in combination with periodogram method calculation each partitioned seismic record power spectrum, solve and obtain random medium power spectrum, Fourier inverse transform is obtained random medium autocorrelation function, after inversion velocity parameter, construct random medium velocity model, in combination with existing geological data completes tunnel front side geological prediction.This method can also restore stratum large-scale velocity distribution and small-scale heterogeneity characteristics simultaneously, effectively improve the accuracy and resolution of tunnel geological prediction, suitable for the advanced prediction scene of complex heterogeneous stratum, provide reliable data support for tunnel construction geological risk prediction.