274 results about "Fourier spectrum" patented technology

A method of modeling dose and focus response in lithographic imaging to simulate an optical critical dimension (OCD) metrology system creates simulated aerial images of the object pattern to be transferred to a resist film on the substrate at different focus settings of the metrology imaging system. The method then successively creates simulated images, at different exposure dose and focus settings of the metrology imaging system, of the latent and developed image of the object pattern in the resist film on the substrate, and the etched image of the object pattern in the substrate. The method converts the simulated images into polygons having more than four sides and determines the Fourier spectrum of the polygons simulating the images of the object pattern. Using the spectrum of the polygons simulating the images of the object pattern, the method then creates simulated aerial images of the object pattern developed in the resist film, at different dose and focus settings, as viewed by the OCD metrology system.

The present invention discloses an SAR (Synthetic Aperture Radar) image target detection method based on a visual attention model and a constant false alarm rate, which mainly solves the problems of a low detection speed and a high clutter false alarm rate in the existing SAR image marine ship target detection technology. The implementation steps of the method are as follows: extracting a saliency map corresponding to an SAR image according to Fourier spectrum residual error information; calculating a saliency threshold, so as to select a potential target area on the saliency map; detecting the potential target area by adopting an adaptive sliding window constant false alarm rate method, and obtaining an initial detection result; and obtaining a final detection result after removing a false alarm from the initial detection result, and extracting a suspected ship target slice, so as to complete a target detection process. The SAR image target detection method based on the visual attention model and the constant false alarm rate provided by the present invention has the advantages of a high calculation speed, a high target detection rate and a low false alarm rate, and meanwhile the method has the advantages of simpleness and easy implementation and can be used for marine ship target detection.

A touch screen that employs a lens-less linear IR sensor array and an IR light source from a single location at the periphery of the screen to illuminate one or more objects proximate to the screen surface and detect light reflected from such objects. The sensor array is paired with a proximal grid-like barrier/reflector to create Moiré patterns on the sensor array. Digital signal processing converts such patterns into discrete Fourier transforms. The peaks of the lower order discrete Fourier spectrum as well as the complex phases of the lower order peaks can be used to determine the locations of the objects proximal to the screen accurately. A small number of pressure or surface acoustic sensors at the periphery of the screen are utilized to improve positioning reliability by providing redundant positioning information and registering physical contacts with the screen.

The invention provides a monitoring method for blade crack of a wind driven generator. The monitoring method mainly includes setup of a piezoelectric ceramic fan crack damage health monitoring system and a fan blade crack damage assessment method. The piezoelectric ceramic fan crack damage health monitoring system mainly comprises piezoelectric ceramic pieces, a function generator and an oscilloscope. The working principle is an active surveillance technology based on a piezoelectric ceramic wave method, and the working procedures include utilizing the function generator to emit sine sweeping-frequency signals and the oscilloscope is used for real-time display and storage for received detection signals. The fan blade crack damage assessment method includes utilizing Fourier spectrum analysis to calculate two defined damage indexes based on wavelet packet analysis, successfully monitoring crack areas and performing verification through time reversal. The monitoring method is easy to operate, and the identification effect of blade crack of the wind driven generator is remarkable. The monitoring method is general, and can be applied to damage monitoring of composite materials similar to fan blades.

An optical fiber Fourier measurement with switching white light interferometer implements Fourier transforms on white light spectrum output from transducer interferometer, the carrier frequency is Fourier spectrum defined by interferometer optical path difference, two sets of carrier frequency components are separated and symmetrical in the frequency space; one set of components is filtered for anti-Fourier transforms and plural logarithm operation, phase information of the transducer interferometer is set as an imaginary part of signals and separated from the background formed by lighting source spectrum outline and interference fringes contrast; the phase information of the transducer interferometer is limited within (minus Pi, Pi) according to operation procedure, the 2 Pi phases polarize of phase information is phase unwrapped, the measuring range is not limited with the 2 Pi phase; absolute optical path difference of transducer interferometer is calculated from phase information, thus realizing testing. The method of the invention prominently increases accuracy of white light spectrum peak measuring method and Fourier peak value frequency switching method.

A device for the production of holographic reconstructions having light modulators is disclosed. The device comprises at least one pixelated light modulator illuminated by at least one light source, and a focusing optical element field arrangement which images the light sources in an image plane after the light modulator. For the reconstruction, only one order of diffraction of the Fourier spectrum of the hologram should be used. The light modulator is provided with an assigned filter-aperture field arrangement which is located in the area of the image plane of the light source images and which has a plurality of aperture openings. Said aperture openings are designed in such a way that they each allow the passage of a prespecified area of the overall dimensions either smaller or the same as a diffraction order of the diffraction spectrum following Fourier transformation and produced from the holographic coding of the light modulator.

The invention discloses a method and device for sound source direction estimation based on time frequency masking and a deep neural network, electronic equipment and a storage medium, and belongs to the field of computer technologies. The method comprises the steps of acquiring a multichannel sound signal; carrying out framing, windowing and Fourier transform on each channel sound signal in the multichannel sound signal so as to form a short-time Fourier spectrum of the multichannel sound signal; carrying out an iterative operation on the short-time Fourier spectrum through a pre-trained neural network model, calculating ratio membranes corresponding to target signals in the multichannel sound signal, and fusing the multiple ratio membranes to form a single ratio membrane; and marking andweighting the multichannel sound signal according to the single ratio membrane to determine the orientation of the target sound source. The method and device for sound source direction estimation based on the time frequency masking and the deep neural network can have strong robustness in the environment with a low signal-to-noise ratio and strong reverberation, and improve the accuracy and stability of direction estimation for the target sound source.

The conductive film has a wiring pattern which, with respect to the frequencies and intensities of moire obtained by applying a human visual response characteristic to the frequency information and intensity information of moire calculated from peak frequencies and peak intensities of the two-dimensional Fourier spectrums of the transmittance image data of the wiring pattern and the transmittance image data of a pixel array pattern, causes the sum of intensities of moire each corresponding to frequencies of moire falling within a frequency range predetermined depending on the visual response characteristic to be less than or equal to a predetermined value. The conductive film allows suppression of moire and significant improvement in visibility.

The invention belongs to the technical field of mobile device data processing, and discloses a mobile terminal system and method based on table character detection and recognition. According to the relationship between the geometric direction of the object in the image and the Fourier spectrum corresponding to the image, the inclination correction is carried out on the collected image to obtain the corrected image. Through OTSU Otsu method to binarize, then define horizontal bar and vertical bar to corrode the check image, dilate the operation to obtain table lines, so as to segment the imageto obtain characters; A convolutional neural network for letter and Chinese character recognition is constructed. By randomly adjusting the brightness of image, expanding the sample of contrast and font thickness, the data can be enhanced, the classification standard can be established automatically, and the adaptability of complex background can be enhanced. The invention integrates image segmentation, character detection and recognition, and realizes table character recognition scanning application program based on convolution neural network.

The invention relates to the field of wind power output power prediction technology, in particular to a short-term wind power prediction method based on EWT-ESN. The method comprises the steps that first, EWT is adopted to disintegrate original wind power with strong nonlinearity and non-stationarity to obtain N AM-FM components, wherein F0 refers to an experience dimension component, and F1 refers to an experience wavelet component; second, an ESN prediction model for all the components is established in combination with characteristics of all the disintegrated components from F0 to FN; third, prediction results of all the components are superposed to obtain a final prediction result; and fourth, prediction result analysis is performed according to error evaluation indexes. According to the method, first, the EWT algorithm is utilized to disintegrate an original sequence of the non-stationary wind power into the AM-FM components with compact support Fourier spectrum characteristics, then ESN is utilized to perform prediction on all the AM-FM components, and superposition is performed to obtain the final prediction result. Through the method, wind power prediction precision can be effectively improved.

The invention provides a three-dimensional vibration stress relief multitask acquisition and control system which comprises at least one workpiece, at least one vibration exciter, a sensor matched with each workpiece, a mainframe device and a vibration exciter drive unit, wherein, the sensor acquires a three-dimensional signal of each workpiece; the mainframe device classifies and selects distribution of the inherent frequency and the resonant frequency of each workpiece according to the maximum energy absorption principle and the multi-vibration mode principle and drives the vibration exciter drive unit; and the vibration exciter drive unit drives the vibration exciter to vibrate according to the frequency selected by a mainframe so as to eliminate the stress of each workpiece through vibration. The system and a method thereof provided by the invention have the following advantages of achieving more simplified and more convenient acquisition, ensuring that the distribution of the resonant frequency with different vibration patterns of each workpiece is wider and data is more perfect without omission in Fourier spectrum analysis, ensuring that the obtained result is more accurate while classifying and selecting the resonant frequency for Fourier spectrum analysis, and ensuring that vibration ageing treatment effect is better.

The invention discloses the method for full-automatic vibration treating works with spectrum analyzer, comprising the following steps: 1 using the resilient support to support the work; 2 installing exciting device and sensing device on the work, and making exciting device and sensing device connect with controlling device; 3 opening the exciting device and sensing device, automatically carrying out Fourier spectrum analysis for works, getting free frequency and resonance frequency of works; 4 choosing, sorting and ordering the frequencies; 5 confirming the treating time; 6 treating the frequencies; 7 recording the results. The invention has no requirement for the location of supporting position, exciting device and sensing device position, and the process is full-automatic vibration treatment, so the treatment results is constant.

The invention provides an evaluation method for the ageing state of a composite insulator. The method comprises the following steps: selecting the umbrella skirt of an insulator at a high-voltage or medium-voltage side of a string of insulators, taking samples at different positions and slicing the samples into test pieces; taking a middle test piece of the umbrella skirt of an insulator at a low-voltage side as a reference test piece; detecting the ageing degree of each test piece by using Fourier spectrometry and calculating the change rate of the mean values of absorption peaks of test pieces at different directions relative to the reference test piece; and evaluating the ageing degree of the composite insulator according to the change rate. According to the method, the ageing state of the composite insulator is quantitatively analyzed through standardized sampling and evaluating programs; and the method has the characteristics of simple and convenient testing and high accuracy.

A scanning spot microscope for performing a Fourier spectral analysis has means for performing a repeatable scanning operation which includes scanning an incident light spot to successive locations of a specimen. An interferometer is placed across an optical light path of the microscope, the interferometer including a birefringent device between polarizing devices in the path and introducing a given path difference. Means are provided for receiving and recording an optical signal due to the incident light spot from each successive specimen location. In use the given path difference is maintained during each scanning operation but is varied between scanning operations so that the optical signals relating to these specimen locations and the values of the given path difference can be recorded.

The invention discloses an electromagnetic interference monitoring and identification method for a power LTE wireless private network. The method comprises two processes: spectrum monitoring and interference identification. The spectrum monitoring comprises the steps: employing a scanning heterodyne type frequency spectrum monitoring design at a high frequency band; through multi-stage frequency conversion processing, converting an input signal to a lower intermediate frequency, and then adopting a Fourier spectrum monitoring design at a middle frequency band to perform A/D sampling quantification on the signal which is converted to the intermediate frequency, converting the signal into a digital signal, and then employing a digital intermediate frequency technology and Fourier transform to complete spectrum monitoring. The interference source identification process comprises the following steps: firstly, performing preprocessing, feature extraction and feature selection on acquired data, learning a relationship between acquired signal features and an interference source by utilizing a machine learning algorithm to obtain a classification model based on interference source identification, extracting features from a test signal, and identifying a result by adopting the obtained classification model. According to the invention, frequency spectrum monitoring and interference identification functions of the electromagnetic frequency spectrum can be tightly combined according to the requirements of a power system, and the method is suitable for a 1.8 GLTE wireless private network.

The present invention relates to a single-pixel holographic camera, belonging to the field of holographic imaging. The working process of the system comprises the stages of recording and reconstruction. In the recording stage, the transformation matrix of a space amplitude modulating device is used to encode the Fourier spectral information of the Fresnel diffraction hologram of an object, the analysis and record of a time varying signal are completed by a single pixel intensity detection module, the corresponding measurement is carried out through changing the transformation matrix of the space amplitude modulating device for many times, and finally the compressed sensing imaging result of the Fourier spectrum of object Fresnel diffraction hologram is obtained. In the reconstruction stage, according to the selected encoding matrix, by using a minimization L1 norm algorithm, the recovery of spectral information is carried out, and the Fresnel diffraction hologram of the object is reconstructed through the Fourier transformation.

A quasi-translator for economically producing pure, smooth translational motion with broad arcuate or error-free motion regardless of orientation, which is useful in numerous interferometer applications including spectroscopy, a Fourier modulator and a Fourier spectrometer are provided. The quasi-translator utilizes a support, an arm including a driving magnet on a first end and a driven element on a second end, an axis for rotation of the arm, a bearing system that controls the rotation of the arm about the axis, a drive coil and a drive amplifier to drive the arm in the arcuate motion. The quasi-translator may be employed in a Fourier modulator to change the optical path difference of the interferometer/quasi-translator at a substantially constant rate of change. The quasi-translator and/or Fourier modulator may be used in a Fourier spectrometer to create an optical spectrum from a light beam and/or electrical signal created from the light beam.

A quasi-translator for economically producing pure, smooth translational motion with broad arcuate or error-free motion regardless of orientation, which is useful in numerous interferometer applications including spectroscopy, a Fourier modulator and a Fourier spectrometer are provided. The quasi-translator utilizes a support, an arm including a driving magnet on a first end and a driven element on a second end, an axis for rotation of the arm, a bearing system that controls the rotation of the arm about the axis, a drive coil and a drive amplifier to drive the arm in the arcuate motion. The quasi-translator may be employed in a Fourier modulator to change the optical path difference of the interferometer/quasi-translator at a substantially constant rate of change. The quasi-translator and/or Fourier modulator may be used in a Fourier spectrometer to create an optical spectrum from a light beam and/or electrical signal created from the light beam.

The invention relates to spectrum extreme value temperature detecting method. It includes the4 following steps: infrared radiation ray of the object is collected by the condenser lens into Fourier analysis spectrograph; scanning, recording spectrograph curve, and storing the spectrum into computer; calculating out the object temperature by Wien's displacement law according to the peak value wavelength of the spectrum curve; displaying on the display screen. The range of the measuring temperature is 300-3000k. The invention has the advantages of high measuring precision, wide measuring range.

The invention discloses an extensive angle measuring method for an inclination angle of a plane moving mirror in a Fourier spectrometer, which is used in the Fourier spectrometer of which moving mirror is a plane mirror, and provides accurate feedback quantity for dynamic calibration control. By inverting the phase delay of each reference laser detection element signal in real time, the method measures the inclination angle of the moving mirror. The method comprises: continuously and synchronously triggering and sampling two pairs of orthogonal signals Ia and Ia' and Ib and Ib' at high speed, and calculating the orthogonal signals to acquire a real-time direct current component parameter and an alternating current component amplitude parameter as a digital filter value parameter and a normalized parameter; sampling and normalizing the digital filter value of the signals to obtain two points (Ia', Ia'') and (Ib', Ib'') on a unit circle; calculating the phases of the two points, and limiting the phases within [0, 2phi) so as to obtain a phase difference; adjusting the phase difference by reasonably setting a threshold value; and finally calculating the inclination amount of the moving mirror according to the relation of the phase difference and the inclination angle of the moving mirror. The method can achieve overall high-precision extensive measurement of the inclination angle of the moving mirror.

The invention discloses a rubbing acoustic emission denoise method based on empirical wavelet transform. The method comprises the following steps that (1) an acoustic emission signal is acquired through a rubbing acoustic emission experimental device; (2) adaptive partition is performed on the acoustic emission signal according to the Fourier spectrum features; (3) a wavelet window is added after partition, and an empirical scale function and an empirical wavelet function are defined; (4) empirical wavelet transform is defined; and (5) wavelet denoising is performed on each empirical mode component fi and then reconstruction is performed based on EWT. The beneficial effects of the rubbing acoustic emission denoise method based on empirical wavelet transform are that adaptive partition is performed according to the Fourier spectrum of the acoustic emission signal, and a wavelet filter bank is constructed to extract different intrinsic mode components included in the acoustic emission signal so that less modes are decomposed and the phenomena of mode aliasing and endpoint effect can be effectively filtered; and wavelet denoising is performed on each empirical mode component, reconstruction is performed based on EWT and denoising is performed on the signal so that the denoised signal has high signal-to-noise ratio and the denoise effect is obvious.

The invention provides a printed file identifying method based on powdered ink stack texture analysis. At first, printed character stroke images on printed files are respectively collected through a high-precision microscopic amplifying system; small powdered ink stack blocks are extracted from the printed stroke images so that a normalized powdered ink texture picture is formed; the texture features of the printed files are extracted in a way that the texture features of the normalized texture image are extracted through a local binary pattern, a gray level concurrence matrix, a Fourier spectrum, a Gabor technology and a Wavelet technology; and the text features of the extracted printed files are classified into different patterns through a principle component analysis and a linear discriminant analysis, thus a user can judge whether the two printed files are printed and generated through the same printer or not. Through the printed file distinguishing method, the automatic printed file identification which is based on computer image analysis and has independent texts is realized and the accuracy can reach above 89 percent.

The invention discloses an object three-dimensional shape measurement method using a single pixel detector and a device thereof. A structural light field generator generates a series of cosine distribution lighting light fields which light target objects in turn through a lighting lens group; an imaging lens group performs imaging of the lighted target objects to a plane grating device so as to form target object images modulated by the plane grating device; the single pixel detector receives light signals of the modulated target object images in turn according to different lighting light fields and outputs electric signal response values in turn, and calculates the Fourier spectrum primary component I<1><~> of the modulated target object images by utilizing a series of electric signal response values; modulation phase distribution of the target object images is calculated through I<1><~>, and difference value calculation is performed on modulation phase distribution of the target object images and modulation phase distribution of reference plane plate images so that phase difference distribution deltaphi(x,y) is obtained; and then the measured values of height distribution h(x,y) of the surface shape of the target objects to be measured are obtained by utilizing the corresponding relation of phase difference and height.

The invention discloses a frequency-multiplier klystron and a manufacture method thereof, relating to the technique of electron tubes. A microwave actuating signal with the frequency of f is used as an input signal; electron beams are in manual action with multiple resonant cavities of the conventional klystron in vacuum; ultraharmonics components in the Fourier spectrum of the electron beams are obviously increased after good cybotaxis is achieved; an output structure adopts the output structure of a wave band where frequency nf is positioned or utilizes the higher order mode of the conventional structure; the ultraharmonics components of the frequency nf, namely, the input frequency f and the output frequency nf, are derived from the electron beams in high cybotaxis so that the microwave small signal is amplified and the frequency is multiplied to nf from f strictly in integer multiples. The method of the invention is simple and easy to implement, and the manufactured frequency-multiplier klystron can keep comparative frequency multiplication grain, good spectrum purity, wider absolute frequency multiplication bandwidth and higher power capability.

The invention provides an intrinsic frequency measuring method which can be widely used for measuring the intrinsic frequency of structures which are formed by permeability magnetic materials such as pipelines, anchor rods, steel wire ropes, stay cables, plates and tanks or non-permeability magnetic materials. According to the intrinsic frequency measuring method, contact type or non-contact type excitation and detection of a vibration signal are achieved by means of a sensor according to the magnetostrictive effect and the inverse magnetostrictive effect, so that the Fourier spectrum distribution curve corresponding to a system frequency response function H[a],[b] (f) is obtained, and the peak point of the Fourier spectrum distribution curve corresponding to the system frequency response function H[a],[b] (f) is determined, so that the intrinsic frequency of a system is obtained, wherein a is a measure point, and b is an excitation point. According to the intrinsic frequency measuring method, contact measurement is available, measurement of the lift-off distance between a large sensor and an object to be measured is also available, weak vibration signals can be detected, and the intrinsic frequency measuring method has a broad application prospect in intrinsic frequency measurement.