42 results about "Spectral density function" patented technology

The invention discloses a method for regulating and controlling a cosine multi-Gaussian correlation structure light field, and the method comprises the steps: introducing a hyperbolic cosine function and a multi-Gaussian function, and constructing a weighting function and a kernel function based on the hyperbolic cosine function and the multi-Gaussian function; introducing a partially coherent light construction formula, and constructing a cross spectral density function of a cosine multi-Gaussian correlation structure light field at the source plane by combining a weighting function and a kernel function; introducing a free space transmission formula, and constructing a light intensity expression of a cosine multi-Gaussian correlation structure light field at any transmission distance according to a cross spectral density function, namely, an expression of the cosine multi-Gaussian correlation structure light field; adjusting the transmission distance and parameters of the cosine multi-Gaussian correlation structure light field to obtain light intensity distribution regulation and control of the cosine multi-Gaussian correlation structure light field, and further obtaining an array form in which sub-beams are flat-topped beams according to the light intensity distribution regulation and control; according to the invention, controllable transmission of the cosine multi-Gaussian correlation structure light field can be realized, and effective regulation and control of the array form in which the sub-beams are flat-topped beams can be realized.

Disclosed in the present invention are a method and apparatus for synthesizing spatially cross-correlated multi-point ground motions fitting a response spectrum. The method comprises: using an influence matrix method to obtain ground motion acceleration time histories fitting a target reaction spectrum with high precision, and calculating a Fourier amplitude spectrum and a phase spectrum thereof; and considering a calculation relationship between a power spectral density function and the Fourier amplitude spectrum, taking the power spectral density function of the obtained time histories as an initial value, using a random vibration theory and Cholesky decomposition to obtain spatially cross-correlated multi-point ground motion time histories, further taking into account a phase spectrum of the ground motion time histories fitting the target reaction spectrum with high precision, and performing correction and iteration to obtain spatially cross-correlated multi-point ground motions fitting a response spectrum. The present invention overcomes the shortcomings in current multi-point ground motion time history synthesis techniques, such as the difficulty in ensuring good fitting to a target response spectrum and the non-stationarity of synthesized ground motions, helping to improve the reliability of dynamic response analysis results for large-scale engineering structures under the action of multi-point ground motions.

The invention discloses a method for generating a hollow light array with rectangular distribution. The method comprises the following steps: constructing a kernel function based on a spiral phase and a Gaussian function; superposing hyperbolic cosine functions to construct a weighting function so as to obtain a multi-cosine correlation vortex light field; introducing a partially coherent light construction formula, and constructing a cross spectral density function of the multi-cosine correlation vortex light field at the initial plane in combination with the kernel function and the weighting function; a free space transmission formula is introduced, a light intensity expression of the multi-cosine correlation vortex light field at any transmission distance is constructed in combination with a cross spectral density function, parameters of the transmission distance and the multi-cosine correlation vortex light field are adjusted, and light intensity distribution regulation and control of the multi-cosine correlation vortex light field are obtained. According to parameter regulation and control, the array form that the sub-beams are hollow beams is obtained, and a rectangular distribution hollow light array is obtained; according to the invention, the controllable transmission of the multi-cosine Gaussian correlation vortex beam can be realized, and the effective regulation and control of the array distribution with the sub-beams being hollow beams can be realized.

The invention relates to a method and a system for generating a fractional order circular coherent correlation light beam, and relates to the technical field of partially coherent light beam design, and the method comprises the following steps: in a space-frequency domain, representing a partially coherent light beam through a cross-spectral density function, and converting the cross-spectral density function into an integral form; a fractional order is introduced into the cross-spectral density function in the integral form to serve as a regulation dimension, and a cross-spectral density function of the partially coherent light beams at the light source is obtained; normalizing the cross spectral density function at the light source to obtain a coherence degree function of the partially coherent light beams; representing the propagation process of the partially coherent light beams, and representing a cross-spectral density function in a discrete form; and substituting the representation of the partially coherent light beam in the propagation process and the cross spectral density function in the discrete form into the coherence degree function to obtain a fractional order circular coherent correlation light beam. According to the invention, a fractional order circular coherent correlation beam with beam shaping capability is constructed.

The present application provides a kind of quantitative evaluation method of the influence of wind tunnel inner surface roughness on airflow quality, belongs to the technical field of wind tunnel, the present application is collected by laser confocal scanner wall roughness multi-resolution point cloud data, high frequency, medium frequency and low frequency roughness component is extracted by wavelet decomposition, power spectral density function and fractal dimension are calculated to establish random roughness field probability distribution model, local velocity field and vorticity distribution are obtained by using lattice Boltzmann algorithm to simulate rough wall near flow field, the uniformity of airflow is calculated by generating equivalent random roughness field sample using Monte Carlo method for statistical analysis, the polynomial mapping function of roughness statistical characteristic parameter and airflow quality degradation index is established, when degradation index exceeds allowable threshold, wall roughness is over standard, solve the technical problems of low precision and insufficient calculation efficiency in quantitative evaluation of the influence of multi-scale random roughness on wind tunnel airflow quality.

The invention relates to a signal bandwidth estimation method for power spectral density function integration, which is used for realizing bandwidth estimation of a signal under a satellite communication channel, and comprises the following steps of: firstly, performing fast Fourier transform (FFT) on the signal, squaring a module value of the converted signal, and then converting a component value to obtain power spectral density; integrating the power spectrum density, and obtaining rough estimation values of the upper limit and the lower limit of the signal in the frequency spectrum according to the extreme value of the slope change of the integrated power spectrum; and performing power change estimation on the power spectral density according to the coarse estimation value to obtain a fine estimation value, and converting the real bandwidth of the signal according to the sampling rate of the signal and the FFT point number. According to the invention, high-precision bandwidth estimation under low calculation complexity can be realized.

A method of forming an illumination mode using an illumination system comprising an array of individually controllable reflective elements arranged to direct portions of a radiation beam to desired locations in a pupil plane. The method comprises allocating different reflective elements of the array to direct radiation to different locations in the illumination mode by: determining a desired power spectral density function of radiation directed by the array of reflective elements to the illumination mode, the desired power spectral density function including a cutoff frequency; applying different phases to frequency components of the power spectral density function; transforming the power spectral density function into a spatial domain signal that varies as a function of positions of the reflective elements; and using the spatial domain signal to allocate reflective elements that direct radiation to different locations in the illumination mode.

The invention relates to a method and a system for simulating internal noise of a slave clock in a master-slave synchronization network in the technical field of clock synchronization. The method comprises the following steps: establishing a first equivalent model and a second equivalent model; generating a first phase-locked loop output power spectral density function based on the first equivalent model, and generating a second phase-locked loop output power spectral density function based on the second equivalent model; calculating equivalent loop bandwidth conditions of the first equivalent model and the second equivalent model; a second phase-locked loop output power spectral density function is updated by using a loop bandwidth condition, a gain coefficient and a slave clock bandwidth of a second equivalent model are calculated by using a TDEV template and an MTIE template, and the second phase-locked loop output power spectral density function is updated for the second time to obtain a noise generation time domain function; the problem that the stability of the slave clock cannot be accurately simulated due to the fact that the MTIE corresponding to the generated time domain noise exceeds the limit of the MTIE template because only the TDEV template is considered and the MTIE template is not considered in the existing method for simulating the internal noise of the slave clock is solved.

The application discloses a method for generating a flat-top beam array, comprising the following steps: introducing a multi-Gaussian function and a hyperbolic function, superimposing the hyperbolic function, constructing a weight function and a kernel function with Gaussian distribution intensity based on the superimposed hyperbolic function and the multi-Gaussian function; introducing a partial coherent light construction formula, combining the weight function and the kernel function to obtain a cross-spectral density function of a multi-cosine multi-Gaussian correlation light field containing a multi-cosine function at a source plane; introducing a free space transmission formula, constructing an intensity expression of the multi-cosine multi-Gaussian correlation light field at an arbitrary transmission distance according to the cross-spectral density function of the multi-cosine multi-Gaussian correlation light field, that is, an expression of the multi-cosine multi-Gaussian correlation light field; adjusting the transmission distance and the parameters of the multi-cosine multi-Gaussian correlation light field to obtain a flat-top beam array with different numbers of rows and columns, and realizing an array form with adjustable flat-top sub-beams; and the application can effectively control the number of the flat-top beam array sub-beams.

The invention relates to an offshore wind speed synthesis method and a wind power prediction method. The method is suitable for the technical field of offshore wind power. The technical problem to be solved by the invention is to provide an offshore wind speed synthesis method and a wind power prediction method. According to the technical scheme, the offshore wind speed synthesis method comprises the steps of generating wind speed data under a second time scale on the basis of an average wind speed under a first time scale in combination with a Weibull distribution model and wind speed time characteristics; and generating wind speed data under a third time scale based on the wind speed data under the second time scale in combination with a Vor-karman power spectral density function and an autoregressive moving average model.

The application discloses a kind of based on the partial coherence light field generation method and system of multi-core optical fiber, method includes: according to the cross spectral density function of target partial coherence light field determines multiple electric field modes and generates hologram;The phase distortion between the each core of multi-core optical fiber is measured and compensation chart is generated;After the superposition of both as synthetic hologram, the wavefront modulation of incident laser is carried out;Modulated light is coupled into multi-core optical fiber and exports target light field.The corresponding system includes mode and compensation chart generation module, hologram synthesis module, wavefront modulation module and coupling transmission module.The present application realizes system miniaturization and strong environmental adaptability using multi-core optical fiber, by hologram sequence and phase compensation combination, can flexibly generate and transmit multiple partial coherence light with specific spatial coherence structure, solve the problem that prior art is not flexible, difficult to apply in tortuous narrow environment.

The application discloses a method for measuring threshold enhancement factor size by using spectral effective width, and belongs to the technical field of laser design; the method comprises the following steps: encoding a PRBS signal; based on the phase of the PRBS signal, modulating a fiber laser at a preset modulation depth to obtain a power spectral density function after phase modulation; performing denoising processing on the power spectral density function after phase modulation to obtain a spectral effective width; and measuring the threshold enhancement factor size according to the spectral effective width. The application also provides a system for measuring threshold enhancement factor size by using spectral effective width. The application provides a spectral effective width calculation method, and aims to solve the problems of large calculation error and incomplete application of the spectral effective width in the existing simulation.

A kind of underwater vehicle noise prediction correction method based on bayesian inference, calculation model (1) includes Corcos autospectrum and Corcos normalized cross power spectral density function calculation model;According to calculation model (1), construct the schematic diagram (2) of bayesian network, the key factor identification and state analysis of the key factor of the modeling of the influencing factor of turbulent fluctuation pressure in bayesian network in schematic diagram (2) of bayesian network are built-in bayesian inference;According to the schematic diagram (2) of bayesian network, model in NETICA software, construct directed acyclic bayesian network (3);Reference calculation model (1) and directed acyclic bayesian network (3) are simulated setting (4) and noise signal comparison (5).The present application has the advantages of ensuring the precision of low-frequency noise prediction in sparse grid large size, improves the problem that the grid scale of finite element model and the space related scale of turbulent boundary layer pressure do not match and the calculation amount is too large when fine grid is used.

The invention discloses a self-similar fluctuating wind speed frequency spectrum simulation method, a storage medium and electronic equipment, and the method comprises the steps: obtaining an actually-measured wind number, carrying out the data analysis, and carrying out the calculation to obtain a power spectrum density function, an average wind speed and a turbulence value in three component directions; determining Kaimal power spectrums of the three component directions according to the average wind speed and the turbulence value of the three component directions, and determining connection frequencies of the three component directions by combining a power spectrum density function; generating a low-frequency wind speed curve from the low-frequency part smaller than the connection frequency by adopting a harmonic superposition method; a Weierstrass-Mandelbrot function is adopted for the high-frequency part with the frequency larger than the connection frequency to generate a high-frequency wind speed curve; and superposing the low-frequency wind speed curve and the high-frequency wind speed curve to synthesize a pulse wind speed curve. A harmonic superposition method and a Weierstrass-Mandelbrot function simulation method are fused, the randomness and the multi-scale performance of real atmospheric wind speed fluctuation can be simulated, meanwhile, the multi-scale characteristic of the real atmospheric wind speed fluctuation is achieved, and input conditions closer to the real wind condition are provided for load calculation of a draught fan.

The invention discloses an extreme wave spectrum calculation method based on a wave element co-occurrence recurrence period, and belongs to the technical field of coast and ocean engineering. Comprising the following steps: acquiring significant wave height and spectral peak period length time sequence data of a certain station, constructing an annual extreme value sample pair, and mapping the annual extreme value sample pair to a unified probability space; based on the Copula theory, quantitative characterization is carried out on a dependent structure among wave elements, and optimal selection is carried out on candidate Copula models according to an AIC information criterion; determining a joint exceeding target probability according to the co-occurrence recurrence period definition, and determining a joint design point based on a maximum probability density criterion; and based on the joint design points, inversely calculating spectral scale parameters through zero-order spectral moment energy matching and finishing effective wave height consistency checking, and further calculating an extreme wave spectral density function curve meeting the co-occurrence recurrence period constraint. According to the method, the co-occurrence recurrence period design sea condition is determined, wave spectrum calculation self-consistency is achieved, and the rationality and engineering applicability of an extreme wave spectrum calculation result are improved.

The invention belongs to the technical field of aircraft fatigue life design, and particularly relates to a random stress amplitude vibration fatigue curve determination method and device. The method comprises the following steps: carrying out random vibration response analysis on a structural dynamic finite element model of a cantilever beam with one end clamped and supported, and obtaining a vibration stress power spectral density function and a vibration stress root-mean-square; determining a k-order moment of the power spectral density function; determining an expected value of the number of stress amplitudes in unit time; determining a coefficient value of a vibration stress amplitude probability density function formula, and determining vibration fatigue life time by using a Miner damage accumulation theory; determining a random vibration fatigue life cycle number; and determining a curve parallel to the equal stress amplitude S-N curve and passing through the random vibration fatigue life cycle number and the vibration stress root-mean-square corresponding point as a random stress amplitude vibration fatigue curve. The random stress amplitude vibration fatigue curve constructed by the invention improves the efficiency of evaluating the vibration fatigue life of the structure.

The invention belongs to the technical field of image analysis, and provides an image noise analysis method and system, and the method can respond to an image input instruction, verify an input image based on a preset condition, convert the verified input image into a grayscale image, obtain an image frequency spectrum based on the grayscale image, and calculate a power distribution spectrum of the image frequency spectrum. Averaging the power distribution spectrum along the radial direction to extract a power spectrum density function, analyzing the power spectrum density function through a logarithm fitting mode, and displaying an analysis result. According to the scheme provided by the invention, an efficient, accurate and automatic noise analysis means is provided, the noise characteristics of the image can be analyzed in a concentrated manner, the overall noise characteristics of the image can be extracted, interference of local noise is avoided, noise analysis is smoother and more accurate, the spectral characteristics of the image noise can be quantitatively described, and the method is suitable for popularization and application. A user can visually know the noise characteristics in the image, and the accuracy of image quality evaluation and processing can be improved.

The invention provides a substation network slice division and interference suppression method and system, and relates to the technical field of network slices. Comprising the following steps: analyzing terminal request data and network channel data to establish a planning function, solving the planning function to generate initial network slices, establishing a dynamic evolution equation according to the initial network slices, deducing an interference transfer function between the initial network slices, and alternately solving to obtain an optimal power spectral density function and a time-frequency resource block allocation rule. Carrying out interference component separation and phase compensation on an interfered signal, quantifying a network resource state deviation degree in combination with quality evaluation processing, and reconstructing an initial network slice to obtain a network slice; the execution efficiency, the reliability and the anti-interference performance of substation network slice division are improved, and the communication service quality is optimized.

The application relates to a method and system for simulating internal noise of a slave clock in a master-slave synchronization network in the technical field of clock synchronization, and comprises the following steps: establishing a first equivalent model and a second equivalent model; generating a first phase-locked loop output power spectral density function based on the first equivalent model and generating a second phase-locked loop output power spectral density function based on the second equivalent model; calculating a loop bandwidth condition equivalent to the first equivalent model and the second equivalent model; updating the second phase-locked loop output power spectral density function using the loop bandwidth condition, and calculating the gain coefficient and the slave clock bandwidth of the second equivalent model using a TDEV template and an MTIE template, and then updating the second phase-locked loop output power spectral density function again to obtain a noise generation time domain function. The method solves the problem that the existing method for simulating internal noise of a slave clock only considers a TDEV template and does not consider an MTIE template, so that the corresponding MTIE of the generated time domain noise exceeds the MTIE template limit, and the stability of the slave clock cannot be accurately simulated.

This invention discloses a polar underwater pulse normal wave acoustic ranging method, belonging to the field of polar acoustic ranging. Based on the physical characteristics of low-frequency normal waves in the polar environment, a passive distance estimation method for low-frequency long-distance pulse sound sources in polar seas, based on a single hydrophone, is proposed. The method includes the following steps: acquiring actual polar sound field environmental parameters; collecting and filtering signals with the hydrophone; calculating the power spectral density function of the signal; estimating the normal wave dispersion constant and waveguide invariants; calculating the dispersion reduction transform of the power spectral density function; and determining the sound source distance based on the maximum value principle. Results demonstrate that the proposed method can effectively estimate the distance of pulses in polar underwater environments.

The invention discloses a lateral deviation measurement system and method based on modulated sine waves, and belongs to the technical field of space laser interference and optical precision measurement, and the method comprises the steps: in a laser heterodyne interference measurement and control system, an advanced pointing mechanism is driven to make periodic sine deflection with the frequency of Y. Detecting a phase value of a beat frequency signal in the four-quadrant detector through a phase meter; decoupling a time domain light beam included angle and a time domain optical path difference; solving a logarithmic amplitude spectral density function of the light beam included angle and the optical path difference; solving a complex mode of the logarithmic amplitude spectral density function of the light beam included angle and the optical path difference at the frequency of the modulated sinusoidal signal; calculating lateral offset through the complex modulus ratio of the optical path difference to the light beam included angle; and judging whether the lateral offset is smaller than a threshold value, if so, inhibiting the TTL coupling effect, otherwise, adjusting the high-precision displacement table through the controller to reduce the lateral offset, and circulating the steps until the lateral offset is smaller than the threshold value. According to the invention, high-precision quantization and suppression of lateral offset are realized.

The invention discloses a weighted multi-scale entropy-based electroencephalogram signal analysis method and a cognitive function state evaluation system, and the method comprises the steps: carrying out the preprocessing of collected original electroencephalogram signals, so as to remove noise and artifacts; multi-scale entropy calculation is carried out on the preprocessed electroencephalogram signals, and entropy value sequences of the electroencephalogram signals under multiple time scales are obtained; calculating energy distribution of the preprocessed electroencephalogram signals on different frequency bands through a power spectral density function, wherein the energy distribution is used for quantitatively representing activity intensity of each electroencephalogram frequency band; determining a weight factor corresponding to each time scale based on the energy distribution on different frequency bands; and carrying out weighted fusion on the entropy value sequence by using a weight factor, and calculating to obtain a weighted multi-scale entropy. In this way, the complexity measurement can represent the dynamic characteristics on the time scale and the structural change of the frequency energy dimension at the same time, and therefore time-frequency double-domain fusion analysis of the electroencephalogram signals is achieved.

This invention discloses a rotor damping ratio identification method based on key phase sensing measurement, belonging to the technical field of rotating machinery. The method includes: bandpass filtering of the key phase signal; calculating the self-power spectral density and then implementing vectorized Hampel filtering to construct a window matrix to detect and replace outliers caused by harmonics; reconstructing the complex spectrum and inversely transforming it to generate a time-domain pulse decay signal; extracting eigenvalues ​​using an inverse autoregressive model and automatically obtaining stability parameters using a clustering algorithm. This method analyzes the modal parameters of the rotor through key phase signals, expanding the application of key phase signals in rotor dynamics analysis. During signal analysis, the power spectral density function is treated as a special "time series," and vectorized Hampel filtering achieves excellent harmonic interference effects. Furthermore, replacing the cyclic sliding window with vectorized operations significantly improves computational efficiency, providing a reliable technical means for real-time monitoring of rotating machinery.

The application discloses a method for regulating and controlling cosine multi-Gaussian associated structured light field, comprising the following steps: introducing hyperbolic cosine function and multi-Gaussian function, constructing weight function and kernel function based on the hyperbolic cosine function and the multi-Gaussian function; introducing a partial coherent light construction formula, combining the weight function and the kernel function to construct the cross-spectral density function of the cosine multi-Gaussian associated structured light field at a source plane; introducing a free space transmission formula, constructing the light intensity expression of the cosine multi-Gaussian associated structured light field at an arbitrary transmission distance according to the cross-spectral density function, i.e. the expression of the cosine multi-Gaussian associated structured light field; adjusting the transmission distance and the parameters of the cosine multi-Gaussian associated structured light field to obtain the light intensity distribution regulation of the cosine multi-Gaussian associated structured light field, and then obtaining the array form of the sub-beam as a flat-top beam according to the light intensity distribution regulation; the application can realize the controllable transmission of the cosine multi-Gaussian associated structured light field and effectively regulate and control the array form of the sub-beam as a flat-top beam.

The invention discloses an offshore structure fatigue damage assessment method and related equipment, and the method comprises the steps: obtaining the stress time history and duration of an offshore structure, and obtaining a power spectral density function through Fourier transform; spectral moment parameters are extracted, characteristic spectral width parameter pairs are constructed, and stress distribution moment parameters are established in combination with the reverse slope of the S-N curve of the material; and finally, the damage amount is calculated according to the S-N curve type, the fatigue damage amount is calculated by directly utilizing a stress distribution moment parameter, a spectrum moment parameter and a material constant when the slope is single, and a result is obtained through piecewise integration of multiple slopes through a bi-component probability density function. The method is based on frequency domain parameter analysis, does not need complete long-term stress recording, greatly reduces the calculation and storage cost, and meets the requirements of real-time evaluation and the like. Gaussian broadband signal features are accurately captured through spectral moment parameter and feature spectral width parameter pairs, and the prediction precision under complex working conditions is remarkably improved. A unified framework is constructed by means of stress distribution moment parameters, and different types of S-N curves and fatigue limit effects can be compatible.

The invention relates to the technical field of simulation calculation, and discloses a photovoltaic support foundation design method based on wind energy simulation calculation, and the method comprises the steps: introducing a self-spectral density function in a random vibration theory to describe the turbulence intensity of a single-point wind speed based on specific meteorological and topographic data of a photovoltaic support target site; outputting a three-dimensional fluctuating wind field model containing complete information of spatial and temporal distribution of wind pressure; taking the obtained three-dimensional fluctuating wind field model as a fluid domain boundary condition, acting on a parameterized photovoltaic array overall structure model, and performing complete transient fluid-solid coupling simulation calculation; outputting the substrate dynamic response time history of the reaction force and the torque of six degrees of freedom at the top connection part of each support foundation along with the time change; and outputting the most unfavorable design internal force and long-term displacement of the foundation after the influence of the quantized wind-induced vibration second-order effect. According to the method, the structural response envelope value of the whole wind vibration process is directly obtained through time-history analysis.

The invention relates to the technical field of optical sensing fiber-optic gyroscopes, in particular to a fiber-optic gyroscope optical path spectral error analysis method based on OSA and OCDP fusion, which comprises the following steps: measuring a power spectral density function of a fiber-optic gyroscope light source and spectral transmission functions of a coupler and a Y waveguide; acquiring a polarization coupling intensity distribution curve; obtaining the optical path difference and the amplitude intensity ratio of a plurality of characteristic coupling points of the polarization coupling intensity distribution curve; sequentially multiplying the power spectral density function of the optical fiber gyroscope light source and the spectral transmission functions of the coupler and the Y waveguide to obtain an ideal normalized main spectrum; obtaining a full-optical-path spectrum of the fiber-optic gyroscope based on the ideal normalized main spectrum and the optical path difference and the amplitude-intensity ratio of the plurality of feature coupling points; analyzing based on the full-optical-path spectrum to obtain a physical defect position and error intensity; the error analysis accuracy of the fiber-optic gyroscope can be improved.

The invention discloses an efficient simulation method and system for a steady fluctuating wind field based on adaptive wave number sampling. The method comprises the following steps: obtaining frequency discrete points; calculating an equivalent probability density function; obtaining an equivalent cumulative distribution function, obtaining wavenumber discrete points, and calculating a discrete value of the equivalent cumulative distribution function under the wavenumber corresponding to each wavenumber discrete point; obtaining non-uniform wavenumber discrete sampling points of a wavenumber domain; obtaining a frequency-wavenumber discrete point matrix and a non-uniform wavenumber discrete point interval matrix of the frequency-wavenumber joint power spectral density function; and generating a wind speed time history sample of the simulation point by adopting fast Fourier transform and non-uniform fast Fourier transform. According to the method, the non-uniform discrete sampling points are obtained, the characteristics of the given frequency-wave number joint spectrum on the wave number domain can be well captured, the self-adaption is high, the wind speed time history sample of each simulation point can be generated by adopting fast Fourier transform and non-uniform fast Fourier transform, and the simulation efficiency and precision can be improved.

A to-be-measured partially coherent fractional vortex beam passes through a scattering object, an error between measurable information and to-be-measured information is minimized by using an optimization algorithm, and a main electric field mode and a weight of a to-be-measured fractional vortex beam are reconstructed by using a multimode stacked diffraction algorithm. A cross-spectral density function of the partially coherent fractional vortex beam is calculated, a cross-spectral density of a partially coherent fractional vortex optical field is reconstructed, and complete information including light intensity, a light intensity association, an electric field association, a phase, and the like of the partially coherent fractional vortex optical field is obtained. After the complete information of the partially coherent fractional vortex optical field is obtained, reverse transmission calculation is performed to obtain a source field vortex phase distribution, thereby implementing accurate topological charge measurement of the fractional vortex beam under low coherence conditions.

The present invention relates to a three-dimensional undulating green generation system for realistic putting simulation. The present invention comprises: an input module that sets terrain generation parameters of the green according to the difficulty or set value of the putting simulation; and a green generation module that generates a undulating surface in three-dimensional space based on the terrain generation parameters. In particular, the green generation module is characterized by generating a random field having an irregular height distribution using a spectral density function, and selectively superimposing tilting and stepping elements thereon to generate a three-dimensional green map similar to an actual field. Furthermore, the present invention provides a realistic putting physics environment by precisely tracking the altitude of the ball through natural coordinate calculations based on triangle elements and dynamically correcting the coefficient of friction according to the slope of the green.