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51 results about "Matrix projection" patented technology

A projection matrix is an square matrix that gives a vector space projection from to a subspace . The columns of are the projections of the standard basis vectors, and is the image of . A square matrix is a projection matrix iff .

Random sampling analog circuit compressed sensing measurement and signal reconstruction method

The invention relates to a random sampling analog circuit compressed sensing measurement and signal reconstruction method, which belongs to the field of electronic system test and fault diagnosis. Aiming at a fault signal having a sparsity distribution characteristic per se or in an orthogonal space in an output response of an analog circuit, a test node is selected according to a circuit topology structure, circuit output responses are randomly sampled under a distributed sensor test network, response signals are expressed in a sparse way on a transform domain by utilizing discrete orthonormal basis, compressed sensing measurement of the sparse signals is completed under observability matrix projection, and when the recovery rate of signal reconstruction by randomly compressed sampling points reaches more than 80 percent, the compressed measurement values of the circuit output responses are effective, can form a characteristic set and can be used for analog circuit fault diagnosis. The method solves the problems that the traditional analog signal sampling occupies a large number of hardware resources, large signal reconstruction calculated amount and the like; and the random sampling compressed sensing measurement method is utilized to improve the efficiency of electronic system testing.
Owner:BEIJING UNIV OF TECH

Frequency domain compressive sensing method aiming at sparse SAR (Synthetic Aperture Radar) images in airspace

The invention discloses a frequency domain compressive sensing method aiming at sparse SAR (Synthetic Aperture Radar) images in airspace and belonging to the technical field of signal processing. The frequency domain compressive sensing method particularly comprises the following steps of: step 1: determining the directions of original SAR images, with sparsity; step 2: carrying out Fourier transform on the original SAR images along the directions with the sparsity to obtain frequency domain images of the directions; step 3: building frequency domain sparse reconstructed models, solving model parameters, establishing observation vectors, and reconstructing frequency domain signals so as to form reconstructed frequency domain images; and step 4: carrying out the Fourier transform on the reconstructed frequency domain images along the directions to obtain reconstructed images. In the invention, by analyzing the sparsity of the SAR images in the airspace, the frequency domain sparse reconstructed models are built by aiming at the frequency domain signals, the model parameters are estimated, projection is carried out on the basis of an appropriate observation matrix and the frequency domain signals are reconstructed by utilizing a small quantity of observed values.
Owner:BEIHANG UNIV

Phase encoding characteristic and multi-metric learning based vague facial image verification method

The invention discloses a phase encoding characteristic and multi-metric learning based vague facial image verification method. The phase encoding characteristic and multi-metric learning based vague facial image verification method comprises (1) a training phase, namely, partitioning sampling images and extracting multi-scale primary characteristics of every image block, performing fisher kernel dictionary learning through the above characteristics to generate into partitioning fisher kernel coding characteristics, performing multi-metric matrix learning on the above coding characteristics to generate a plurality of metric matrixes and obtain the metric distance after training samples are performed on multi-metric matrix projection, calculating the average metric distance and variance of positive samples and negative samples to a set and confirming a final classification threshold through a probability calculation formula of Gaussian distribution and (2) a verification phase, namely, partitioning input facial images and extracting multi-scale primary characteristics, generating partitioning fisher kernel coding characteristics, obtaining the final metric distance through the multi-metric matrix and comparing the distance and the threshold to obtain a facial image verification result. The phase encoding characteristic and multi-metric learning based vague facial image verification method has the advantages that the identification rate is high and the universality is strong.
Owner:SUN YAT SEN UNIV

Inter-class inner-class face change dictionary based single-sample face identification method

The invention discloses an inter-class inner-class face change dictionary based single-sample face identification method to solve the problem of limitations of the current single-sample face identification algorithm. The method comprises the steps of step1, obtaining expressions of face images in the compression domain; step2, building a face image training sample matrix containing k classes; step3, building an average face matrix and an inter-class face change matrix of a face database; step4, adding low rank and sparse constraints into the inter-class face change matrix; step5, solving an inter-class similarity matrix and an inter-class difference matrix; step6, projecting the average face matrix, the inter-class similarity matrix and the inter-class difference matrix to low-dimensionality space; step7, performing normalization processing on the dimensionality reduced average face matrix, the inter-class similarity matrix and the inter-class difference matrix through a normalization method, and performing iterative solution on the face image training sample matrix based sparse coefficient vectors through a norm optimization algorithm; step8, selecting column vector face labels in the average face matrix, which are corresponding to the sparse coefficient maximum, to serve as the final face identification result.
Owner:BEIJING INSTITUTE OF TECHNOLOGYGY

Human face feature extraction and classification method

The invention relates to a human face feature extraction and classification method. The method includes the following steps that feature dimension reduction is performed on human face images through a 2D-PCA method, and a high-dimensional image matrix is converted into a low-dimensional image matrix; the low-dimensional image matrix is converted into one-dimensional column vectors; according to the one-dimensional vectors of images of a training set, an intra-class divergence matrix S<W> and an inter-class divergence matrix S in the training set are solved, and eigenvalue decomposition is performed on the S<W> and the S respectively, wherein the eigenvalue decomposition formulae are as follows: and ; D<alpha> is used for estimating , D<beta> is used for estimating , and the formulae and can be obtained; the column space W<1> of and the column space W<2> of are respectively solved, and the optimum projection space W=[W<1>,W<2>] of a feature extraction algorithm with two stages of LDA based on 2D-PCA is obtained; the low-dimensional image matrix in the first step is projected into the optimum projection space W, and then feature vectors of the images are obtained; classifier training is performed on the feature vectors obtained in the sixth step through an SVM+NDA model, and a final human face classifier is obtained.
Owner:ZHEJIANG UNIV

Method for determining theoretic porosity of fabric through image method

InactiveCN103471974ATightness is objective and accurateQuick calculationPermeability/surface area analysisPorosityCentral line placement
The invention relates to a method for determining the theoretic porosity of a fabric through an image method, and in particular relates to a method for determining the theoretic porosity of a latticed sparse fabric through an image method. The method comprises the following steps of analyzing and processing a sparse fabric image through a digital image processing technology to obtain a theoretic porosity index; converting a gray image into a binary image according to a gray histogram two-peak method threshold of the fabric image, setting the pixel of a yarn region in a binary matrix corresponding to the binary image as 1, respectively projecting the binary matrix in the warp yarn direction and the weft yarn direction, and analyzing the central line positions of warp yarns and weft yarns; analyzing a cut image peripheral region according to the central positions of side yarns, wherein the quantity of the warp yarns and the quantity of the weft yarns in a new image are integers; acquiring the diameters of the yarns according to analysis on a wavy curve formed by projection of the binary matrix; calculating warp tightness and weft tightness so as to obtain the theoretic porosity index. By the adoption of the method, the theoretic porosity index can be objectively, accurately and quickly calculated.
Owner:DONGHUA UNIV

Fully passive polarization quantum state chromatography method and chip

The invention discloses a fully passive polarization quantum state chromatography method and a chip. The method comprises the steps: 1) converting polarization information of a to-be-measured optical signal into path information by using an on-chip integrated polarization-path converter, and respectively outputting the path information through 2n paths of waveguides; 2) leading out an optical signal in each path of waveguide to 3n paths through an on-chip integrated multimode interference device and waveguide crossers, and dividing path information into 6n paths of output light; 3) combining every two output lights on the 6n paths into 3n identical input quantum states by using the waveguide crossers; 4) dividing each input quantum state into two paths of output, measuring each path of output through an on-chip integrated superconducting single-photon detector, and achieving measurement of the input quantum states under any two-dimensional unitary matrix projection basis vector; and 5) fitting a measurement result to reconstruct a density matrix of the quantum states, and realizing the chromatographic measurement of the quantum state. According to the method, the complex quantum state chromatography process is simplified, full automation is achieved, and high expansibility is achieved.
Owner:PEKING UNIV

Observation matrix construction method based on low-coherence unit norm tight frame

ActiveCN111475768AAvoid the problem of difficult structureRobustImage memory managementImage acquisitionComputation complexityTight frame
The invention relates to an observation matrix construction method based on a low-coherence unit norm tight frame, and belongs to the technical field of signal processing, and the method comprises thesteps: S1, initializing an initial observation matrix phi 0 into a random part Fourier matrix, and enabling the initial observation matrix phi 0 to serve as an initial alpha tight frame F; s2, calculating a Gram matrix corresponding to the framework F, and projecting the matrix to a structure constraint set of a tight framework by using a contraction function to generate a new Gram matrix; s3, updating the Gram matrix through a weighted iteration process; s4, reducing the rank of the new Gram matrix, calculating the square root of the new Gram matrix, and finding out a tight frame closest toa unit norm tight frame; and S5, solving the optimal target function to obtain an observation matrix. According to the method, the mutual interference coefficient between the observation matrix and the sparse basis is reduced, the dependence degree on signal sparsity is reduced, the problem that an ETF frame is difficult to construct is avoided, the initial observation matrix is initialized into apart of Fourier matrix, the calculation complexity is reduced, and the pressure of storage and processing equipment is reduced.
Owner:CHONGQING UNIV OF POSTS & TELECOMM

Model order determination method based on S-shaped function random subspace identification

The invention discloses a model order determination method based on S-shaped function random subspace identification. The method comprises the following steps: establishing a Hankel matrix according to a measured structural dynamic response; performing matrix projection calculation on the Hankel matrix to obtain a projection matrix P; carrying out singular value decomposition on the projection matrix, and arranging singular values obtained through decomposition in a descending order; normalizing the singular value sequence arranged in a descending order, and converting singular values to a closed interval of [epsilon, 1-epsilon]; carrying out nonlinear least square fitting on the relationship between the normalized singular value and the order by adopting an S-shaped function in a proper order interval; according to an S-shaped function obtained through fitting, solving a tangent line passing through (n0, 0.5), and then further solving an intersection point (n *, 0) of the selected tangent line and a horizontal axis, so that the model order N of the random subspace is 2. [n *]. The bad influence of a modal omission phenomenon and model order over-estimation on modal parameter identification can be effectively avoided, the method can be applied to adaptive model order determination of various vibration structures, and the accuracy of random subspace identification can be improved.
Owner:SOUTHEAST UNIV

Spatial orientation measuring instrument precision evaluation method based on single-star projection

The invention discloses a spatial orientation measuring instrument precision evaluation method based on single-star projection. The method comprises the specific steps of: firstly, calculating an observation vector of each star point in a measuring instrument body system according to the position coordinates of the star points and a calibration coefficient; secondly, searching an inertial vector corresponding to the star point according to a navigation star number, and projecting the inertial vector to the instrument body system according to an attitude matrix, so as to obtain a projection position vector of the navigation star in the system; thirdly, calculating the deviation of the projection position vector relative to the observation vector, and calculating a three-axis error angle according to a measuring instrument imaging model; and finally, calculating a weight coefficient corresponding to each identified star in the frame of star map according to star magnitude, and comprehensively evaluating the measurement precision of the frame according to a multi-star attitude determination principle. Compared with a polynomial fitting method based on multi-frame analysis and a difference method based on adjacent two-frame analysis, the influence of a spacecraft platform on the method is minimum, and the evaluation result is closest to the measurement precision of an instrument.
Owner:BEIJING INST OF CONTROL ENG
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