36 results about "Diffraction model" patented technology

Post-migration common image gathers (CIGs) are generated in a dip angle domain from measured seismic data. From a CIG, a hybrid Radon model is determined, including a reflection model related to concave features in the CIG and a diffraction model related to linear features in the CIG. The reflection model is transformed with a reflection Radon operator applied along inversion trajectories restricted around apices of the concave features to obtain reflection data. The diffraction model is transformed with a diffraction Radon operator to obtain diffraction data. The reflection and diffraction data at different horizontal positions can then be combined and summed to generate a migrated image of the subsurface.

A method for estimating a radar cross-section (RES) of a given object by using a diffraction model of this object. With the model, it is possible to determine a basis adapted to said object on which is projected a vector of measurement. With the projected vector, it is possible to obtain a more complete reconstructed vector than the measurement vector in terms of incident wave and diffracted wave observation directions/polarizations and the components of which have a better signal/noise ratio than the measurements. The reconstructed vector is then used for calculating the RCS.

A novel method for evaluating the loss index of railway wireless environment path is use in the railway wireless mobile communication system in which the radio wave propagation environment is rather complex. The method is an improvement of the evaluation method for the loss index of land mobile communication system path and is based on wedge-shaped diffraction model and cubic spline interpolation. The method requires the system to provide enough train measurement reporting samples, the time advance of the samples and the distance image take on a V shape, and topographic relief factor is already known. The scheme can effectively reduces the collection cost of evaluation data and selects appropriate evaluation parameter towards different radio wave propagation environment, thus being benefit to reduce computational complexity.

The invention discloses a mode division modulation and multiplexing communication method based on POV light under an ocean turbulence condition. The method comprises the steps: building a diffraction model of POV-like light in a free space based on an ABCD optical system, and obtaining a far-field distribution expression of the POV light; further obtaining a mathematical expression of the OAM detection probability spectrum disturbed by the ocean turbulence; selecting wave parameters of POV light suitable for turbulent ocean wireless optical communication; selecting a phase power spectrum function and a phase screen interval suitable for simulating transmission of POV light in the multi-layer phase screen; calculating instantaneous attenuation and transfer factors of POV light; and constructing a mode division modulation and channel multiplexing communication model based on POV light. According to the method, the POV light is applied to the UWOC system which is limited by ocean turbulence and based on the mode division modulation and channel multiplexing technology, and compared with a UWOC communication system based on traditional vortex light, the method has superior communication performance.

The invention provides a multi-band fusion algorithm based on an improved relaxation algorithm. The algorithm comprises the steps of receiving a plurality of sub-band signals, selecting one sub-band signal from the plurality of sub-band signals as a reference signal, and compensating incoherent terms between the rest sub-band signals and the reference signal based on the improved relaxation algorithm, and estimating geometric diffraction model parameters of the large-bandwidth signal by using an improved relaxation algorithm on the basis of each sub-band signal subjected to incoherent term compensation, and substituting the geometric diffraction model parameters into a geometric diffraction model to reconstruct the large-bandwidth signal. According to the algorithm provided by the invention, in coherent processing, geometric diffraction model parameters of each sub-band are estimated based on an improved relaxation algorithm, and incoherent items are calculated and compensated by usingthe estimated parameters, so that the incoherent items can be accurately estimated under a strong clutter condition; because the algorithm can accurately estimate the frequency sampling point corresponding to the target position, the imaging resolution is high; a missing frequency band signal can be estimated so as to estimate a large-bandwidth radar signal, and the estimation precision is high.

The invention relates to a method and device of extracting the characteristics of a target scattering center, and the implementation of the method of extracting the characteristics of target scattering center comprises the following steps: two-dimensional imaging of the target echo signal, and determining the location of a plurality of candidate scattering centers in the image; selecting two sub-bands in the frequency domain of the echo signal for two-dimensional imaging, and estimating the type parameters of each candidate scattering center by using the pixel values corresponding to the positions of the multiple candidate scattering centers in the two images; constructing a sparse dictionary matrix according to the position and type parameter estimate of the multiple candidate scatteringcenters; solving the two-dimensional geometric diffraction model based on the sparse dictionary matrix, and obtaining the characteristics of multiple scattering centers of the target. The implementation of extracting the characteristics of target scattering center can accurately extract the scattering center characteristics of the target by using two-dimensional geometric diffraction model.

The invention provides a conical surface holographic display method for expanding a vertical field angle. According to the method, firstly, a conical surface diffraction model and a rapid calculation method thereof are provided, then on the basis of the conical surface diffraction model, a conical surface hologram generation and reconstruction method is provided, and the provided conical surface holographic display method can enlarge the vertical direction view field angle of cylindrical surface holographic display. Due to the fact that field angle expansion research and technical methods of holographic display are only limited to the horizontal direction, a method for expanding the field angle in the vertical direction is never researched and put forward. Therefore, the method solves the problem that the field angle in the vertical direction of holographic display is limited for the first time, and has good creativity and novelty; in addition, the method can be applied to desktop holographic three-dimensional display and has great application potential.

The invention provides a photon sieve aberration analysis method. A photon sieve diffraction model is built according to a mathematical relationship between a phase of a pupil plane of a photon sieveand a point spread function, and the point spread function of the photon sieve is calculated; and the phase of the pupil plane of the photon sieve is reversely derived according to the point spread function of the photon sieve, namely, the phase of the pupil plane is an equivalent wave aberration of the photon sieve. Compared with the prior art, the method has the advantages that inertial thinkingis broken through, and starting from the mathematical relationship between the phase of the pupil plane of the photon sieve and the point spread function, the phase of the pupil plane of the photon sieve is reversely derived according to the point spread function of the photon sieve. The wave aberration is an important evaluation index of an optical system, and single aberrations such as a spherical aberration, a coma aberration, astigmatism, field curvature and distortion can be easily derived according to the wave aberration. In addition, a photon sieve wave aberration model is built, so that the mixed design of the photon sieve and other optical systems such as a refraction lens is also facilitated.

The invention relates to a two-dimensional super-resolution radar imaging method based on a fusion technology. The two-dimensional super-resolution radar imaging method comprises the following steps of 1, receiving each sub-band radar signal in each sub-pulse time period; 2, carrying out motion compensation on the signal in each pulse time period; 3, representing the sub-band signals in the pulse time period by using a geometric diffraction model; 4, selecting the sub-band signal distributed in the lowest frequency band as a reference signal, and calculating and compensating the incoherent terms between other sub-band signals and the sub-band signal based on the improved root-MUSIC; 5, based on the improved root-MUSIC, estimating the geometric diffraction model parameters of the large-bandwidth signals from all the sub-band signals subjected to incoherent item compensation; 6, substituting the estimated large-bandwidth signal parameters into the geometric diffraction model to reconstruct a large-bandwidth signal; 7, carrying out distance dimension compression imaging on the estimated large-bandwidth signal; and 8, for a plurality of sub-pulse echo bands corresponding to each distance unit, obtaining a pulse echo signal of long pulse accumulation time, and performing azimuth compression to realize the azimuth super-resolution.

The invention provides a diffraction wave imaging method and device and electronic equipment, wherein the method comprises the following steps: acquiring seismic data and velocity data; carrying out simulation processing on a preset seismic model according to the speed data to obtain simulated seismic data, wherein the seismic model comprises a reflection model and a diffraction model; obtaining awave field residual error objective function and a wave field residual error value based on the seismic data and the simulated seismic data; performing migration processing on the wave field residualerror value to obtain a gradient of a wave field residual error objective function, wherein the gradient comprises a reflection gradient and a diffraction gradient; updating the reflection model andthe diffraction model respectively according to the reflection gradient and the diffraction gradient to obtain an updated reflection model and an updated diffraction model; performing iterative updating processing on the wave field residual error objective function according to the updated reflection model and the updated diffraction model to obtain a diffraction wave imaging result. According tothe diffraction wave imaging method, the migration method is utilized, and the least square idea is combined, thereby effectively improving the diffraction wave imaging precision, and improving the accuracy and the focusing performance of an imaging result.

The invention provides a spherical pure-phase hologram generation method based on a spherical self-diffraction model. The method comprises the following steps: firstly, proposing a spherical self-diffraction calculation model, wherein the diffraction process of the model is that an object plane diffraction field is propagated to the same object plane through spherical center diffraction; generating a spherical pure-phase hologram based on a spherical self-diffraction iterative algorithm; and enabling the spherical surface self-diffraction iterative algorithm mainly to depend on object surfaceamplitude to provide iterative amplitude limitation, so that rapid convergence of the iterative algorithm is guaranteed by utilizing energy conservation of the same object surface so as to generate aspherical surface pure phase hologram capable of being reconstructed at high quality. Compared with a traditional iterative algorithm, the reconstructed image of the spherical pure-phase hologram generated by adopting the method is high in quality, and speckle noise of the reconstructed image of the spherical pure-phase hologram is effectively suppressed.

The invention provides a multi-network auxiliary positioning method for a distributed large-scale multi-antenna system. A diffraction model used for feature collection is introduced into RSS-based DBN positioning, the new RSS features effectively consider the influence of other UE on target UE, and the adaptability of a trained DLBP network in a multi-user scene is improved; the motion trail of a UE is analyzed by utilizing LSTMN under the condition that only a small amount of trail information exists, the complete trail of the UE can be effectively obtained by utilizing a DBN estimation result and a small amount of position samples, and compared with a traditional method, the historical trail information acquisition and measurement cost is greatly reduced; and according to the method, the estimation results of the DBN and the LSTMN are combined through the BPNN, and high positioning precision can be achieved.

The invention provides a cylindrical holographic occlusion removing method based on an optical path limiting function. According to the method, on the basis of a concentric double-cylindrical-surfacediffraction model, a diffraction propagation point spread function is limited by adopting the optical path limiting function, so that the purpose of removing cylindrical holographic self-occlusion isachieved. The optical path limiting function HOLF is determined by the magnitude relation between the angle direction propagation optical path difference Dop and the system parameter Pc, when the Dopis larger than the Pc, the HOLF is 0, shielding is removed, and otherwise, shielding is not removed. According to the provided de-occlusion method, the quality of the reconstructed image is high, andthe de-overlapping effect is remarkable; meanwhile, the calculation amount additionally increased by the optical path limiting function is very small, and the calculation and generation speed of the cylindrical hologram is not influenced; the method can also be used for cylindrical holographic display of a three-dimensional object based on cylindrical chromatography, and has a good application prospect.

The invention discloses an image processing method and device, a storage medium and a terminal, which relate to the technical field of image processing. The method comprises steps of firstly, acquiring a target image shot by a camera assembly, wherein the target image comprises a diffraction image area, then obtaining an inverse operation result corresponding to the display screen assembly, wherein the inverse operation result is a result obtained by performing inverse operation on a diffraction model of diffraction of the display screen assembly, and finally, eliminating the diffraction image area in the target image based on the inverse operation result. Because the light is diffracted when passing through the display screen assembly and forms the diffraction image area in the target image, the diffraction model of diffraction of the display screen assembly is subjected to inverse operation, and the diffraction image area in the target image can be effectively eliminated according to the inverse operation result. And the photographing effect of the camera assembly below the screen assembly is effectively improved.

The invention discloses a method for measuring displacement of quasi-sphere cell in height direction in lens-free imaging system, and the method comprises the steps: building a Fresnel diffraction model according to the characteristics of a lensless imaging system, and building a quasi-sphere cell height direction displacement measurement model of the lensless imaging system; obtaining a distance from the diffraction ring of the quasi-sphere cell to the real cell boundary through the diffraction image of the quasi-sphere cell in the biological cell sample to be measured, and substituting the distance into the measurement model to obtain the displacement of the quasi-sphere cell in the height direction. The method can solve the problem that the displacement of the quasi-sphere cells in the micro-fluidic chip in the height direction cannot be accurately measured, is very suitable for POTC combining the micro-fluidic chip and lens-free imaging, is simple to operate and high in real-time performance, and has very important significance on biological cell detection combining a lens-free imaging system and micro-fluidic.

A multi-LED multiplexing 3D-FPM reconstruction algorithm based on a multi-layer diffraction model relates to the technical field of computational imaging, solves the problem that the acquisition rate is too slow when a plurality of LEDs illuminate, and comprises the following steps: step 1, constructing a loss function between a low-resolution picture obtained by the multi-layer diffraction model and a low-resolution picture actually acquired by a camera; step 2, updating a sample refractive index function of the thin sample layer by adopting a gradient descent method by utilizing the newest loss function, the newest incident light complex amplitude of the thin sample layer and the newest sample refractive index function of the thin sample layer, and updating a phase part of a newest pupil function by utilizing the gradient descent method; and step 3, judging whether the number of times of completing the step 2 reaches a preset number, if so, outputting a sample refractive index function, and otherwise, performing the step 1 again according to an updated result. According to the method, the number of LR pictures needing to be collected is greatly reduced, meanwhile, the influence of system aberration on a reconstruction result is effectively reduced, and the reconstruction precision of an algorithm is improved.

The invention discloses a method and a system for measuring plasma parameters of femtosecond laser-induced gas ionization, picosecond laser is used as detection light to detect the dynamic evolution process of plasma obtained by femtosecond laser-induced gas ionization, and a diffraction model is established based on Fraunhofer diffraction and Fresnel diffraction theories; the detected diffraction spectrum is fit with a diffraction spectrum obtained based on a diffraction model to obtain detection light phase shift frequency domain evolution and further obtain time domain evolution of plasma parameters; according to the invention, the space-time evolution process of the plasma can be obtained in single shot measurement, and a delay line in the device does not need to be adjusted for repeated measurement in the measurement process, so that the operation process is greatly simplified, the measurement time is saved, the measurement error is reduced, and the detection accuracy is improved; and moreover, the time domain evolution of the plasma parameters can be calculated and obtained only by fitting the diffraction spectrum for one time, multiple times of extraction and fitting are not needed, and the parameter obtaining speed is improved to a great extent.

The invention relates to the technical field of power equipment assets, and discloses a power equipment asset unified modeling method, which comprises the following steps: acquiring three-dimensional model data of power equipment, and performing space division on a three-dimensional model of the power equipment; extracting model sub-bodies located in the plurality of sub-spaces, and extracting coordinate information of feature points of the model sub-bodies; coordinate information of feature points of the model daughter is extracted, and according to the position coordinate information of the feature points, a closed entity taking a surface formed by the feature points as an external boundary is constructed as a diffraction model daughter of the model daughter; and in the three-dimensional model of the original power equipment, replacing the model daughter with the diffraction model daughter corresponding to the model daughter so as to form the diffraction model of the power equipment. The original complex model data is replaced by the simple entity, so that the three-dimensional model data does not occupy too much computer memory during the matching design of the subsequent power equipment, and the probability of computer jamming or crash is reduced.