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154results about How to "Good anti-noise performance" patented technology

Image mosaic method based on neighborhood Zernike pseudo-matrix of characteristic points

The invention relates to an image mosaic method based on neighborhood Zernike pseudo-matrix of characteristic points, which leads image statistical information (Zernike pseudo-matrix) to be interrelated with the characteristic points of an image by using the following steps: firstly, extracting interest points of an inference image and an input image by utilizing a Harris angle detector, and taking rectangular neighborhoods using the interest points as a center as a local characteristic region with characteristic matching; secondly, calculating the Zernike pseudo-matrix to the rectangular characteristic regions to be used as descriptors of the characteristic region, and realizing the matching of the characteristic points through comparing the Euclidean distance of the characteristic vector of the descriptor of each characteristic region. The matching can have less wrong matching points which are eliminated through a RANSAC (RANdom Sample Consensus) algorithm, and the right matching relation can be calculated to realize the image mosaic. The invention can effectively realize the image registration and mosaic with geometric transformation relations of translation, rotation, small scale zooming, and the like, and can be used for image treatment and image synthesis of fields such as communication, multimedia technology, and the like.
Owner:郭宝龙 +1

Linear frequency-modulated parameter estimating method and implementing device thereof

The invention belongs to the technical field of digital signal processing and provides a linear frequency-modulated parameter estimating method with high precision, low complexity, high speed and high efficiency and an implementing device thereof. The invention adopts a technical scheme that: by means of an energy barycentre interpolation estimation and Radon ambiguity transformation (RAT) based modulating frequency estimating method, the method mainly comprises the following steps of: for a given input signal s(n), calculating an ambiguity function AFs(tau, xi) of the input signal s(n); exchanging scanning straight lines xi=k tau continuously; figuring out the projection of AFs(tau, xi) on the scanning straight lines by means of Radon transformation; recording all projection values; constructing a panorama discrete spectrum; searching out the peak position of the panorama discrete spectrum; estimating the projection value of the actual peak value; obtaining the estimated value of thesignal modulating frequency; searching out the peak value spectrum of a fractional order Fourier spectrum; and figuring out the energy barycentre position of the spectrum so as to estimate the signalbarycentre frequency. The method is mainly applied to the linear modulating frequency signal parameter estimation in the digital signal processing.
Owner:LIANYUNGANG RES INST NANJING UNIV OF SCI & TECH

Rapid fingerprint identification method

The invention discloses a rapid fingerprint identification method based on image characteristics and minutia characteristics. The method comprises the following steps: firstly, detecting a reference point and determining a direction thereof, and determining the reference direction of the reference point by observing the difference between the fingerprint direction and the radial direction in sector regions with different sizes; carrying out image characteristic extraction, performing feature selection after normalization, and finally, obtaining the characteristic vector of the fingerprint image; establishing a minutia template and transforming the obtained minutiae under a polar coordinate system to establish a fingerprint minutia template; and carrying out the characteristic matching, i.e. as for the input fingerprints to be compared, judging whether the two fingerprints are matched or nor by using the fingerprint image characteristics and the minutia template obtained from the three steps. The invention not only can effectively inhibit the influence generated during the fingerprint image translation and the rotation, but also avoids the dependence to the detected reference point and the direction thereof in the recognition process and can also rapidly and accurately judge whether the fingerprint to be identified is matched with the template fingerprint or not.
Owner:NANJING UNIV OF SCI & TECH

Pseudo-differential capacitive successive approximation register analog-digital converter

The invention discloses a pseudo-differential capacitive successive approximation register analog-digital converter. The analog-digital converter comprises a first capacitor array, a second capacitor array, a calibration capacitor array and a comparator, wherein lower-bit-segment sub-capacitor arrays of the first capacitor array keep single-end structures; a higher-bit first-segment sub-capacitor array of the first capacitor array and the second capacitor array construct a differential structure; and the first capacitor array and the second capacitor array construct a pseudo-differential capacitor array in which single ends are combined with the differential structure. In an analog-digital conversion process, a transition code value is formed after completion of a least-significant differential weight bit, thereby realizing differential-single end transition. An output end of the calibration capacitor array is connected with an output end of the second capacitor array through a coupling capacitor, and the calibration capacitor array is used for calibrating mismatch of capacitors in the pseudo-differential capacitor array and the offset of the comparator. Through adoption of the analog-digital converter, the chip area can be saved; self-calibration can be performed; and the conversion accuracy is increased.
Owner:SHANGHAI HUAHONG GRACE SEMICON MFG CORP

Method and device for measuring frequencies of high-frequency cosine signals under undersampling rate

The invention discloses a method and device for measuring the frequencies of high-frequency cosine signals under the undersampling rate, and relates to the field of digital signal processing. By combining the type of the zero crossing point with the distribution characteristic of apFFT phase spectrums, L spectrum position index values are selected from 2L peak value magnitude spectrum positions; according to the remainder selecting result, each apFFT phase spectrum is corrected through the all-phase ratio interpolation method so that the frequency of the apFFT phase spectrum can be estimated; the frequency estimation value obtained after each apFFT phase spectrum is corrected is used as a remainder, the remainders are processed according to the Chinese remainder theorem of the closed analysis form, and the frequencies of the original high-frequency signals are reconstituted through the frequency estimation values. According to the method and the device, the frequencies of the multiple paths of high-frequency cosine signals under the undersampling rate are measured, and the measuring range of the frequencies of the high-frequency signals is greatly widened; the novel spectrum correction method is adopted, and therefore the measuring accuracy of the frequencies of the high-frequency cosine signals is improved, and novel anti-noise performance of the high-frequency cosine signals under the low undersampling rate is ensured.
Owner:TIANJIN UNIV

Hyperspectral image nonlinear abundance estimation method based on constrained least squares

The invention belongs to the technical field of remote sensing image processing and particularly relates to a hyperspectral image nonlinear abundance estimation method based on constrained least squares. According to the method, through introducing abundance nonnegative constraint, abundance sum-to-one constrain and the bounded constraint of a nonlinear parameter, a hyperspectral image nonlinear unmixing problem is transformed into a problem of solving the constraint nonlinear least squares of an abundance vector and the nonlinear parameter. Furthermore, an alternating iteration optimization algorithm is employed to solve the problem. According to the method, starting from a mixed model of a hyperspectral observation pixel, combined with abundance and nonlinear physics significances in the model, the shortcomings of linear unmixing are effectively overcome, and the method also has good anti noise performance and can be used as an effective solution of the hyperspectral remote sensing image nonlinear unmixing. The method has an important application value at the aspect of high precision unmixing based on a hyperspectral remote sensing image and the detection and identification of a ground target.
Owner:FUDAN UNIV

High precision frequency measurement method and instrument at under-sampling rate

The invention discloses a high precision frequency measurement method and instrument at the under-sampling rate. The method includes the steps that spectrum correction is conducted through a triple-spectrum-line interpolation method, L pairs of frequency estimated values obtained after spectrum correction is obtained, and L pairs of phase information obtained after peak position correction is obtained; with the combination of the zero crossing point type and the L pairs of phase information obtained after correction, L frequency estimation values are picked out from the L pairs of frequency estimation values; all spectrum correction values and the L frequency estimation values are adopted as the remainder, and the frequency of an original high-frequency signal is reconstituted according to the Chinese remainder theorem in the closed analytical form. According to the measurement instrument, a single to be tested is subjected to the zero crossing point measurement processing firstly, and the original phase of the signal to be tested is determined; then sample sequences are obtained after analog / digital converter sampling with multi-path sampling frequency is conducted, the sample sequences enter a DSP device in the form of parallel digital input respectively, and frequency estimation of a high-frequency signal is obtained after internal processing is conducted through the DSP device; finally the frequency value is displayed with the help of an output driver and a display circuit of the output driver.
Owner:TIANJIN UNIV

Nonlinear un-mixing method of hyperspectral images based on kernel sparse nonnegative matrix decomposition

InactiveCN104392243ASolve nonlinear unmixingOvercoming the Insufficiency of Linear UnmixingCharacter and pattern recognitionMatrix decompositionAlgorithm
The invention relates to a nonlinear un-mixing method of hyperspectral images based on kernel sparse nonnegative matrix decomposition. The nonlinear un-mixing method comprises the following steps: estimating the number of end members for hyperspectral images by utilizing a dimension virtual method; then, popularizing the conventional un-mixing algorithm based on a linear mixing model to a nonlinear characteristic space by utilizing a kernel method, and solving a nonlinear spectrum un-mixing problem by using an alternative iterative optimization method. The nonlinear un-mixing method of hyperspectral images based on kernel sparse nonnegative matrix decomposition has the beneficial effects that from a mixing model of hyperspectral observation pixels, the sparsity of the hyperspectral abundance is added into a sparse model, and the linear mixing model is mapped into a nonlinear mixing model by virtue of the kernel method, so that the defects of linear un-mixing are effectively overcome, and good noise resistances are simultaneously achieved, and therefore, the nonlinear un-mixing method can be used as an effective means for solving the un-mixing of hyperspectral remote sensing images.
Owner:扬州匠新精密数控设备有限公司

Method for detecting high impedance grounding fault based on fault resistance nonlinear identification

A method for detecting a high impedance grounding fault based on fault resistance nonlinear identification comprises the steps: collecting phase voltages of a detected feeder line and an instantaneous value of a zero sequence current, respectively calculating a correlation coefficient of each phase voltage and the zero sequence current, if the correlation coefficient of one phase voltage and the zero sequence current is larger than a threshold value R, fitting a current voltage characteristic curve composed of the phase voltage and the zero sequence current in a sectional and linear mode through a least square method, accordingly, calculating and obtaining a coefficient, namely, a fault resistance nonlinear coefficient which can effectively present characteristics of the high impedance grounding fault according to the slope of each fitting straight line, judging whether a suspected high impedance grounding fault exists by comparing the fault resistance nonlinear coefficient and the threshold value, continuously detecting the lasting time of the suspected high impedance grounding fault, and if the lasting time exceeds delayed time, finally judging that the high impedance grounding fault occurs. Compared with a detecting method based on a harmonic wave, the method achieves high sensitivity, and compared with a method simply based on the time domain amount, the method achieves a better noise resisting capacity.
Owner:TSINGHUA UNIV

Image tracking method and device based on multi-neighborhood-aided two-dimensional ultrasonic deformed microstructure

The invention designs an image tracking method based on multi-neighborhood-aided two-dimensional ultrasonic deformed microstructure, which comprises the steps as follows: a two-dimensional ultrasonic cardiogram of a tested heart object is collected under a high frame frequency condition and used for offline analysis firstly; then any visible image is used as a selected initial frame of a region of interest (ROI) so that the ROI includes cardiac muscular tissues, simultaneously the interferences of grey scale signals is eliminated; after the ROI of the initial frame on an initial image I is completely selected, the original ROI is set as a center; moreover, the ROI and eight areas coating the surrounding of the original ROI and having same sizes are used as a new searching source region, the tracking vectors of all subregions with the sizes the same as the size of the original ROI in the searching area are traversed through an SAD (Sum of Absolute Differences) arithmetic; and weighted average is implemented on each tracking vector finally, thus obtaining the tracking result of the original ROI. Compared with the traditional SAD tracking method, the neighborhood tracking result of the ROI is sufficiently considered; therefore, the image tracking method based on multi-neighborhood-aided two-dimensional ultrasonic deformed microstructure has excellent noise immunity, and is especially beneficial for movement estimation and parameter calculation on movement issues.
Owner:SICHUAN ACADEMY OF MEDICAL SCI SICHUAN PROVINCIAL PEOPLES HOSPITAL

Edge computing terminal security level evaluation method for random forest

The invention discloses an edge computing terminal security level evaluation method for a random forest. The terminal security level evaluation method comprises the following steps: S1, setting security test items of a terminal and test results of the security test items; S2, testing the accessed intelligent terminal; S3, determining a corresponding relationship between the security level of the intelligent terminal and the single test result set; S4, calculating a security level corresponding to each edge terminal to obtain a data set; S5, dividing the data set into a training set and a testset; s6, inputting the training set into a random forest for training to obtain a mature classifier model; s7, inputting the test set into a random forest classifier model obtained through training, and comparing an obtained test result with the security level in the step S4 to obtain a standard classifier; and S8, evaluating the security level of the newly accessed terminal by using the standardclassifier model. According to the method, the data security requirements of the edge terminal are divided according to the grades, and edge computing side terminal security assessment can be carriedout through a quantized objective standard according to confronted security risks and system complexity.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA +1
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