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35 results about "Set estimation" patented technology

In statistics, a random vector x is classically represented by a probability density function. In a set-membership approach or set estimation, x is represented by a set X to which x is assumed to belong. This means that the support of the probability distribution function of x is included inside X. On the one hand, representing random vectors by sets makes it possible to provide fewer assumptions on the random variables (such as independence) and dealing with nonlinearities is easier. On the other hand, a probability distribution function provides a more accurate information than a set enclosing its support.

Self-adaptive valid signal type positioning method for determining leakage of fluid pipeline

The invention belongs to the technical field of leakage and loss prevention, examination and position determining, and discloses a self-adaptive valid signal type positioning method for determining leakage of a fluid pipeline. The method comprises the steps of selecting a primary function of wavelet decomposition based on a pipeline leakage signal; determining the number of the optimal decomposition layer of the wavelet decomposition; determining the threshold, and performing wavelet denoising on the leakage signal by a soft-threshold method; setting estimation length and shift step length ofa valid signal; determining the valid signal in the leakage signal; determining the time delay value of the leakage signal arriving at the head end and the tail end of the pipeline based on the validsignal in the leakage signal; decreasing the length of the valid signal to obtain two time delay value sets; counting the average value of the three time delay value sets to obtain the final time delay value; determining the difference of the times of the leakage signal arriving at the head end and the tail end of the pipeline; and calculating the position of a leakage source based on the time difference. Compared with an existing positioning method, the method has the advantages that the influence of noise on the leakage signal is reduced; and the leakage positioning error is reduced.
Owner:XIDIAN UNIV

Cesium fountain clock and hydrogen clock frequency difference estimation method for optimizing wavelet neural network on basis of genetic algorithm

The invention discloses a cesium fountain clock and hydrogen clock frequency difference estimation method for optimizing a wavelet neural network on the basis of a genetic algorithm, and belongs to the technical field of atomic time scales. Accordingly, cesium fountain clock and hydrogen clock frequency difference data is subjected to preprocessing which comprises outlier detection and missing data quasi complement. Input layers and hidden layers of the wavelet neural network, the number of the hidden layers and wavelet base selection are determined according to the frequency difference data, and a fountain clock data estimation model for optimizing the wavelet neural network on the basis of the genetic algorithm is built for further improving the fountain clock data estimation precision and estimation stability. In the fountain clock controlled hydrogen clock set estimation process, prediction is conducted through the genetic wavelet neural network for the first time, the prediction precision is greatly improved compared with that of an existing linear prediction, data is more stable, and therefore the control precision of a fountain clock controlled hydrogen clock set is improved, and a more accurate basis is provided for generating TA(NIM) higher in stability and accuracy.
Owner:BEIJING UNIV OF TECH

Data assimilation method based on adaptive covariance expansion

The invention discloses a data assimilation method based on adaptive covariance expansion, and the method comprises the steps of obtaining an atmospheric observation value, and carrying out the mode integration based on a t-1 analysis value, and obtaining a forecast field at an analysis moment t; according to the forecast field set, estimating to obtain an ensemble forecast error covariance matrix Pt and an expansion factor vector at the moment t; updating ensemble members of ensemble Kalman filtering in the assimilation initial process by using the expansion factor vector to increase the ensemble variance of new ensemble Kalman filtering to form new ensemble members, and performing iterative updating on the new ensemble members by using an ensemble Kalman filtering method to obtain final analysis ensemble members; and carrying out pattern forecasting by using analysis set members as initial fields. According to the invention, the expansion factor is adjusted, so that the updated prediction error covariance matrix conforms to the statistical relationship of the prediction error covariance, the information quantity and the observation error covariance, the calculated expansion factor is more reasonable, and the assimilation performance is obviously improved.
Owner:NAT UNIV OF DEFENSE TECH

Single-connecting-rod flexible mechanical arm control method and system

ActiveCN108015761AImplement trackingOvercome the difficulty of obtaining accurate model parametersProgramme-controlled manipulatorState spaceSet estimation
The invention provides a single-connecting-rod flexible mechanical arm control method and system. The single-connecting-rod flexible mechanical arm control method comprises the following steps: acquiring the value of the state quantity of a single-connecting-rod flexible mechanical arm in real time; according to the value of the state quantity, utilizing a set estimation model to estimate unknownparameters in a state space model of the single-connecting-rod flexible mechanical arm and to obtain the estimated value of the corresponding unknown parameter; according to the given track, the estimated value of the unknown parameter and a self-adaption near-optimality control rate formula, obtaining a controlled quantity to enable the controlled quantity to control the single-connecting-rod flexible mechanical arm to run along the given track; and utilizing the controlled quantity to control the single-connecting-rod flexible mechanical arm to run. With adoption of the single-connecting-rodflexible mechanical arm control method, under the condition that the value of the unknown parameter in the state space model of the single-connecting-rod flexible mechanical arm is unknown, the single-connecting-rod flexible mechanical arm can be controlled through the controlled quantity to realize the situation that the tail end of the single-connecting-rod flexible mechanical arm tails after the given track.
Owner:THE HONG KONG POLYTECHNIC UNIV SHENZHEN RES INST

Method and device for estimating frequency modulation ratio of linear frequency modulation signal

The invention provides a method and a device for estimating the frequency modulation ratio of a linear frequency modulation signal. The method comprises the following steps: presetting a time delay set; determining a received current signal; performing autocorrelation operation on the current signal and each signal which is a set time delay from the current signal to get autocorrelation functions corresponding to the set time delays respectively; performing FFT operation on the autocorrelation functions corresponding to the set time delays to get corresponding fuzzy functions; determining the over-threshold peak positions in the fuzzy functions corresponding to the set time delays to get corresponding over-threshold peak position sets; judging the linear relationship between the over-threshold peak positions in the over-threshold peak position sets corresponding to the different set time delays, determining target over-threshold peak positions satisfying the linear relationship in the different set time delays, and forming a target over-threshold peak position set; and estimating the frequency modulation ratio according to the target over-threshold peak position set. With the method and the device, estimation within a large frequency range is realized, and the accuracy of frequency modulation ratio estimation is improved.
Owner:大唐联诚信息系统技术有限公司

Medical purpose neural network robustness verification method and system based on shell protection

The invention discloses a medical purpose neural network robustness verification method and system based on shell protection. Physical examination data of a healthy user is collected; generating an input set based on the physical examination data of the healthy user; the input set serves as a root node of the binary tree, each layer of node is obtained by bisecting a super rectangle represented by a father node of the node until the super rectangle represented by a certain layer of node reaches the specified size limit, bisecting is not continued any more, the current layer of node is a leaf node, and the binary tree for searching is obtained; traversing the binary tree, searching each node of the binary tree, inputting the hyper-rectangle represented by each node of the binary tree into a neural network to be verified, and outputting a reachable set by the neural network to be verified; if it is found that the output reachable set estimation of the hyper-rectangle represented by a certain leaf node is not included in the output limitation, obtaining a conclusion that the current neural network to be verified is unsafe; otherwise, obtaining a conclusion that the current to-be-verified neural network is safe.
Owner:SHANDONG UNIV

Time-frequency dual-selection channel estimation method and device based on structured compressed sensing

The invention discloses a time-frequency dual-selection channel estimation method and device based on structured compressed sensing. The method comprises the following steps: performing, by a transmitting end, transmission by using orthogonal frequency division multiplexing OFDM, transmitting, and filling a time domain training sequence in the time domain, meanwhile setting a part of the subcarriers in the frequency domain as a frequency domain pilot group, and transmitting the frequency domain pilot group after analog processing; performing cross-correlation on the received training sequenceand the transmitted time domain training sequence to obtain position labels whose autocorrelation vectors are greater than a preset threshold so as to form non-zero set estimation of channel impulse response; performing frame reconstruction on a received OFDM frame and converting the received OFDM frame into a circular convolution for transmitting the OFDM frame and the channel impulse response; and obtaining an observation matrix according to a preset frequency domain pilot group, and estimating a time-frequency dual-selection channel by using non-zero subcarriers in the received pilot groupand a partial non-zero set of the channel impulse responses through the structured compressed sensing. The method has the characteristics of low complexity, high spectral efficiency and high precision.
Owner:RESEARCH INSTITUTE OF TSINGHUA UNIVERSITY IN SHENZHEN +1
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