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335 results about "Window Width" patented technology

Health state assessment method for rotary machine based on probability density function

The invention relates to a health state assessment method for a rotary machine based on statistical methods such as kernel density estimation and K-L divergence calculation. The method comprises the following steps that 1) original vibration data of a monitored object is collected; 2) time-domain and frequency-domain features are extracted from the original vibration data; 3) the dimensions of the time-domain and frequency-domain features are reduced to obtain sensitive features; 4) a movable sliding window of the width k is used to dynamically select sample sets, and the statistical characteristics of the sample sets are calculated; 5) the probability density function of each sample set under each sensitive feature is calculated; 6) the K-L divergence between the probability density functions of two adjacent sample sets under the same sensitive feature is calculated; and 7) an integrated K-L divergence is calculated and serves as a health assessment index of the monitored object. The health state assessment method has the advantages that the statistical uncertainty of the samples is fully considered, and the accuracy and generalization performance of a health state assessment model are improved.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA

Voltage sag detection method for S-transformation on basis of time-frequency gathering characteristic criteria

The invention discloses a voltage sag detection method for S-transformation on the basis of time-frequency gathering characteristic criteria. The method includes the first step of obtaining voltage sag disturbance signals to be detected generated in a power distribution network, the second step of conducting analog-digital conversion on an obtained voltage sag disturbance signal model, the third step of conducting optimized selection on gaussian time-frequency window width adjustment parameters in an improved S-transformation method according to time-frequency gathering characteristic criteria, substituting the gaussian time-frequency window width adjustment parameters selected according to empirical values, and conducting characteristic extraction, detection and analysis on digital signals to be detected in the second step through the improved S-transformation. Selection of condition parameters of a gaussian window function is optimized through the constraint condition that the value of a time-frequency gathering characteristic expression is maximized when the signals are analyzed through the improved S-transformation, and the improved S-transformation is applied to characteristic extraction, detection and analysis on voltage sags. The voltage sag detection method for S-transformation on the basis of time-frequency gathering characteristic criteria has the higher detection accuracy degree and signal denoising capacity on transient-state electric energy quality signals.
Owner:JIANGSU UNIV

Design and adjusting method for fuel oil metering device starting flow characteristics

Disclosed is a design and adjusting method for fuel oil metering device starting flow characteristics. The design and adjusting method for the fuel oil metering device starting flow characteristics includes the following six steps: 1) a valve adopting a rectangular fuel window is calculated by adopting a constant pressure difference fuel oil metering flow metering method so that the starting flow characteristics are linear; 2) a bypass adjusting element is arranged so that an intercept of the starting flow characteristics can be adjusted; 3) a fuel oil metering device is used as a standard part, the parameters such as pressure intensity difference of differential pressure valves or differential pressure fuel oil return valves, a metering valve core initial position feedback value, metering valve oil fuel control window width and bypass adjusting element circulation area are respectively in the middle range of design allowable errors; 4) the installation position of a metering valve core displacement sensor is adjusted; 5) a rake ratio of an adjusted product starting flow characteristics are enabled to be equal to that of the standard part; 6) the intercept of the adjusted product starting flow characteristics can be equal to that of the standard part. The design and adjusting method for the fuel oil metering device starting flow characteristics has the advantages that uniformity of the starting flow characteristics can be greatly improved, and good interchangeability of the fuel oil metering device can be ensured.
Owner:AECC SHENYANG ENGINE RES INST

Rolling bearing fault intelligent diagnosis method based on improved S-transformation and deep learning

The invention discloses a rolling bearing fault intelligent diagnosis method based on improved S-transformation and deep learning. According to the method, a window width adjustment factor is added toS-transformation, so that the window width of a Gaussian window function can be changed, and therefore, the time-frequency resolution of the S-transformation can be improved, and the S-transformationcan accurately detect an impact component in vibration signals, and thus, the fault characteristics of the vibration signals of a rolling bearing can be better extracted. Improved S-transformation isperformed on the vibration signals of the fault of the bearing, so that the feature matrix of the signals can be obtained; the feature matrix is subjected to column-based expansion so as be convertedinto a feature vector, and the feature vector is inputted into a sparse autoencoder model; on the basis of the characteristics of the encoder, the deep features of the data are further extracted, sothat some important hidden information that is not recognized by humans can be mined; the extracted features are accurately classified. With the method of the invention adopted, the accuracy of the fault diagnosis of the rolling bearing can be effectively improved.
Owner:YANSHAN UNIV

Satellite navigation positioning resolving method based on Doppler smoothing pseudorange under high-sensitivity environment

The invention discloses a satellite navigation positioning resolving method based on Doppler smoothing pseudorange under a high-sensitivity environment. In the invention, a pseudorange measuring value is smoothened through a Doppler measuring value reproduced by a receiver, the problem of serious distortion of a carrier phase during the smoothing pseudorange of the carrier phase under a condition of weak signals is solved. The method comprises the following steps of: correcting the pseudorange at every new epoch moment according to Doppler frequency offset reproduced by the receiver from the moment to the initial moment to acquire an initial moment pseudorange corrected value; averaging the initial moment pseudorange corrected value to obtain the initial moment pseudorange corrected average value when the quantity of the initial moment pseudorange corrected value reaches to the requirement of window width; and finally carrying out Doppler frequency offset correction from any moment to the initial moment based on the initial moment pseudorange corrected value to finally acquire high-accuracy pseudorange at any moment. The invention is suitable for various satellite navigation positioning resolving systems, such as a GPS (Global Position System), a GLONASS (Global Navigation Satellite System) and the like.
Owner:ZHEJIANG UNIV

Near infrared spectrum analysis method based on CC-PLS-RBFNN optimization model

ActiveCN107064054AHigh precisionReduce Nonlinear Regression ResidualsMaterial analysis by optical meansInfraredCorrelation coefficient
The invention belongs to the field of spectral analysis and especially relates to a near infrared spectrum analysis method based on a CC-PLS-RBFNN optimization model. According to the method, a correlation coefficient method (CC), partial least squares (PLS) and a radial basis function neural network (RBFNN) are combined for optimizing important parameters. The method comprises the following steps: utilizing three-order Savitzky-Golay convolution smooth filtering and first-order derivative correction to preprocess the original spectrum; establishing a PLS model on a whole wavelength section, and optimizing and selecting window width and PLC extracted main constituent quantity; calculating a correlation coefficient of each wavelength variable, selecting the wavelength variable with the correlation coefficient more than a preset threshold value, participating in modeling, and optimizing and selecting the threshold size; utilizing the optimized and selected window width, the main constituent quantity and the wavelength variable to acquire an optimized PLS model; and using a main constituent score and a nature matrix extracted by the optimized PLS model to train the RBF neural network, thereby acquiring the final CC-PLS-RBFNN optimization model. According to the method, the robustness and precision of near infrared spectroscopy analysis can be obviously promoted.
Owner:ZHEJIANG UNIV

Data inquiry method and device

ActiveCN103218423AMake up for the lack of precise querySmall footprintSpecial data processing applicationsLower limitData stream
The invention relates to a data inquiry method and a data inquiry device. The data inquiry method comprises the following steps: receiving inquiry conditions provided by a user, wherein the inquiry conditions comprise inquiry keywords, an edit distance threshold value and a sliding window width; extracting characteristic values of the inquiry keywords to form a keyword characteristic index; extracting characteristics values of basic windows in a current sliding window to form a characteristic index of the sliding window, wherein the sliding window comprises a set number of basic windows and the characteristic index of the sliding window is a queue consisting of characteristic indexes of all the basic windows in the sliding window; when a preset inquiry trigger condition is reached, triggering inquiry for the current sliding window; and according to the keyword characteristic index and the edit distance threshold value, filtering the characteristic index of the current sliding window to obtain a candidate character string set which meets the filtering lower limit. According to the data inquiry method and the data inquiry device, which are disclosed by the invention, the defect of carrying out accurate inquiry of the keywords in a data stream scene can be effectively made up; and the data inquiry method and the data inquiry device have good inquiry fault-tolerant capability.
Owner:INST OF INFORMATION ENG CHINESE ACAD OF SCI

Communication signal modulating and identifying method based on generalized S transformation

The invention provides a communication signal modulating and identifying method based on generalized S transformation. The communication signal modulating and identifying method comprises the following steps of: (1) carrying out analytic signal configuration on an input modulating signal according to the characteristic of an input signal to noise ratio modulating signal to obtain an analytic signal to be used as a signal for carrying out generalized S transformation; (2) configuring a Gaussian window function needed by the generalized S transformation; (3) determining a Gaussian window width factor sigma according to an expression formula of the generalized S transformation; carrying out the generalized S transformation on an input modulation signal by combining short-time Fourier transformation and the Gaussian window function to obtain time-frequency energy distribution images of the modulation signal; and (4) comparing energy images of all modulation signals according to the time-frequency energy distribution images obtained by the step (3) to find out a difference between the time-frequency energy distribution images of all modulation signals which are subjected to the generalized S transformation; selecting a frequency strip quantity with concentrated energy, a maximum value ratio of high-frequency component energy to low-frequency component energy, energy time domain distribution, high-frequency and low-frequency component extreme value time domain distribution and high-frequency component extreme value distribution so as to identify all modulation signals. According to the invention, a high identification rate is achieved under the condition of a low signal to noise ratio, and the method is suitable for modulating and identifying communication signals under a heavy clutter environment.
Owner:BEIHANG UNIV

Steering engine reliability simulation sampling method based on Markova chain Monte Carlo

The invention discloses a steering engine reliability simulation sampling method based on Markova chain Monte Carlo, which comprises four stages: 1, Markova process simulation, namely selecting the initial state of a Markova chain, determining a random transition sampling probability density function, determining the next state of the Markova chain and constantly repeating to generate random sample points, of which the limit distribution is asymptotically optimal, of an importance sampling density function; 2, kernel density estimation, namely selecting a kernel density function, determining a window width parameter and a local bandwidth factor and generating a mixed importance sampling probability density function by using a self-adaptive width and kernel density estimation method according to Markova state points; 3, importance sampling, namely performing importance sampling according to the mixed importance sampling probability density function generated in the second stage; and 4,statistical calculation, performing failure probability estimation according to the important sample points generated in the third stage and calculating the failure probability of the system. The method effectively solves the problems of low simulation efficiency, low precision and mixed system.
Owner:陕西可维卓立科技有限公司

High-spatial resolution long-distance distributed optical fiber temperature strain sensing system

The present invention relates to a high-spatial resolution long-distance distributed optical fiber temperature strain sensing system. The system injects an optical pulse pair of which the pulse widths have a slight difference in a sensing optical fiber based on a pulse pair secondary frequency spectrum differential technology, detects and acquires a time domain brillouin scattering signal generated by each pulse, and adopts two sets of different time window widths to extract the data separately for the spectral analysis, and carries out the secondary frequency spectrum differential operation based on the obtained four sets of brillouin frequency spectrum data, thereby obtaining the space position sensing information covered by the pulse width difference of the optical pulse pair corresponding to the secondary differential brillouin spectrums, and improving the spatial resolution. By designing the pulse widths and the pulse width difference of the optical pulse pair in the system reasonably, the action of a brillouin nonlinear effect is full, and the information within a sensing range of dozens of kilometers is acquired on the condition of keeping a higher signal-to-noise ratio of the system, so that the distributed optical fiber temperature strain sensing system of high spatial resolution (cm magnitude), long distance (greater than 50 kilometers) and high measurement precision (plus or minus 1 DEG C, plus or minus 20 Mu Epsilon) can be realized.
Owner:SOUTH CHINA UNIV OF TECH

Method of modifying dynamic performance of phase-locked loop on basis of sliding filter

The invention discloses a method of modifying dynamic performance of a phase-locked loop on basis of a sliding filter. The method includes: sampling three-phase grid voltage, and performing Park coordinate transform to obtain voltage components v<q> and v<d> in a two-phase dq rotating coordinate system; subjecting the voltage component v<d> to differentiation and then to dividing by an angular frequency parameter, and summing a quotient and the voltage component v<q> to obtain q ; subjecting q to differentiation and then to dividing by the angular frequency parameter, and summing a quotient and the voltage component v<d> to obtain d; subjecting d to the sliding filter to obtain a fundamental wave positive-sequence voltage amplitude V<1><+>; subjecting q to the sliding filter and a PI (proportion integration) regulator, and summing an output of the PI regulator and a preset angular frequency to obtain a grid voltage angular frequency , with the preset angular frequency being power frequency usually; subjecting to differentiation to obtain a grid voltage phase 1+; feeding back 1+ to the input end to finish closed-loop control. The method has the advantages that a proportional algorithm of input signal frequency changes is introduced to MAF-PLL (moving average filter-phase-locked loop), the lowest frequency fluctuation component in the PLL is eliminated, the window width of the MAF is decreased, and dynamic performance of the MAF-DLL is improved.
Owner:SHANDONG UNIV
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