26 results about "Electron density distribution" patented technology

The invention discloses a VLF propagation signal prediction method based on a three-dimensional finite element and a neural network, and belongs to the technical field of electronic communication. The method comprises the following steps: firstly, constructing a geosphere-ionosphere waveguide model based on a three-dimensional frequency domain finite element method, and solving by using a multi-grid method to improve the operation efficiency; secondly, constructing a VLF signal propagation data set of a plurality of known paths at one time based on a three-dimensional frequency domain finite element method; then, constructing a neural network model reflecting a mapping relation between an ionized layer electron density parameter and a VLF wave characteristic based on the data set; then, obtaining electron density distribution on a plurality of known paths based on neural network inversion; and finally, carrying out inversion by adopting an inverse square weight formula to obtain electron density distribution on the to-be-solved path. According to the method, the VLF signal transmission characteristics on multiple paths can be simulated at a time, the workload of modeling simulation is effectively reduced, and the method is suitable for the fields of inversion of a multi-path electron density parameter model, prediction of very low frequency wave propagation and the like.

The invention discloses a plasma field three-dimensional chromatography reconstruction method based on microwave reflection and probe combined measurement, which comprises the following steps: firstly setting the frequency of a microwave antenna and the measurement position of a probe, and then realizing high-precision combined diagnosis of electron density distribution by combining the global non-contact measurement advantage of a microwave reflection method and the local fine measurement capability of an electrostatic probe; and then realizing high-precision fitting of the electron density based on a physical constraint Gaussian process regression model, establishing a mapping relation between the electron density and an emission coefficient, and finally reconstructing a three-dimensional electron density field with millimeter-level resolution.

The invention relates to a terahertz wave diagnosis system and method for plasma in an extreme environment. The diagnosis system comprises a terahertz wave transmitting module, a first terahertz feed source, a first cooling cavity, a first high-temperature-resistant focusing lens, a terahertz wave receiving module, a second terahertz feed source, a second cooling cavity, a second high-temperature-resistant focusing lens and a vector network analyzer assembly. According to the terahertz wave diagnosis system, normal-temperature and normal-pressure environments can be created in high-temperature and low-pressure extreme environments, the effect of protecting the terahertz wave module is achieved, interference of strong electromagnetic interference brought by plasmas on processing of received and transmitted signals is avoided, and link loss is effectively reduced; meanwhile, the terahertz wave is higher in frequency, plasma in a higher electron density state can be diagnosed, the focusing lens transmitting antenna and the focusing lens receiving antenna are adopted, and due to the fact that the terahertz wave is shorter in wavelength and smaller in focused focal spot, electron density distribution with higher spatial resolution can be obtained.

This invention discloses a plasma local current measurement device and method based on optical methods, belonging to the field of optical measurement technology. The device includes: a high-energy pulsed laser, a beam splitter, a photodiode for triggering an ICCD camera, a beam sampling mirror for providing optical signals to the photodiode, a focusing lens for focusing the high-energy pulsed laser, a pulsed power device for generating Z-pinch plasma, a beam collector, an achromatic lens for collecting scattered light, a reflective grating spectrometer, an ICCD camera, and a Mach-Zehnder interferometer. Electron density distribution, electron temperature, ion temperature, plasma velocity, and relative electron-ion drift velocity can be simultaneously obtained through plasma interference fringe images and Thomson scattering spectra. The local current at the measurement point is obtained by multiplying the electron density, electron charge, and relative electron-ion drift velocity at the measurement point.

The application discloses a kind of particle evolution simulation methods based on multi-component plasma radiation effect in tokamak, belong to magnetic confinement controlled nuclear fusion technical field.Firstly, the evolution of impurity density distribution, electron density distribution and ion density distribution is calculated, then continuous radiation and linear radiation are calculated, and then a variety of plasma radiation is accurately added inside magnetic island.Calculating the magnetic field configuration under the plasma radiation correction, and continue to calculate the evolution of plasma total radiation and related parameters under advanced magnetic field configuration, so repeated calculation, achieve the simulation effect of long time evolution.The application realizes the calculation of impurity, electron and ion real-time dynamic distribution, and can also calculate the evolution of a variety of plasma radiation under real three-dimensional magnetic field configuration, and then obtain the plasma related parameter profile at any time;Meanwhile, the spatial distribution of plasma radiation and the situation of magnetohydrodynamic instability under advanced magnetic field configuration are more accurately described.

This invention discloses a method and system for dynamic communication reconfiguration of high-speed aircraft. The method calculates plasma characteristic parameters by real-time acquisition of flight status parameters and communication link quality parameters, establishing a plasma sheath electron density distribution model; calculates plasma attenuation based on electromagnetic wave propagation theory, and predicts future link attenuation using a flight trajectory analytical extrapolation method; determines whether to initiate reconfiguration by integrating multi-dimensional triggering criteria of link attenuation, signal-to-noise ratio, and bit error rate; and jointly optimizes communication frequency, transmit power, and beam pointing angle using a multi-objective collaborative optimization method aimed at minimizing communication interruption probability and maximizing power efficiency. The optimal parameters are then distributed to execute reconfiguration and form a closed-loop control. This invention can dynamically adjust communication parameters according to real-time flight status and plasma characteristics, significantly improving the communication support capability and energy utilization efficiency of high-speed aircraft in a plasma sheath environment.

This invention provides a method for diagnosing parameters of non-uniform plasmas based on the local microwave penetration effect. This method relates to the fields of electromagnetics and plasma diagnostics, and includes a combined diagnosis of the electron density distribution and collision frequency of a plasma profile. The method models the plasma to the left of the peak layer by layer and iteratively optimizes the distribution results. The method also uses the maximum reflection coefficient amplitude slope to derive the plasma electron density peak. For the plasma to the right of the peak, the method models multiple distribution models, determining the model using the attenuation coefficient. Furthermore, the method uses the maximum reflection coefficient amplitude to diagnose the collision frequency. This method addresses the problem of diagnosing parameters of non-uniform plasma profiles.

The invention relates to the technical field of satellite navigation and space environment detection, in particular to an ionosphere electron density reconstruction method based on compressed sensing, which comprises the following steps of: directly outputting a sparse representation matrix aligned with a three-dimensional grid voxel by voxel and support priori and weight of the sparse representation matrix under the input of multi-source data and physical constraint conditions by using a CGAN generator; the problem that the rapid change environment is not matched is solved from the source; physical constraints are added in target generation, and electron density distribution of'spurious spurious spurious' is inhibited; excessive / insufficient regularization caused by fixed weight is avoided on the observation side; according to the quality evaluation, a discriminator is introduced to judge electron density reconstruction and an independent high-credibility reference, error feature confrontation is fed back to a generator and a solver for regularization, closed-loop optimization of generation-reconstruction-evaluation-feedback is achieved, a sparse representation matrix is continuously corrected in an online / quasi-real-time mode, and the quality is evaluated. And the problem of learning solidification deviation of the offline sparse representation matrix is solved.

The invention discloses a method for calculating the electron density of a large-scale structure of a medium weft slot in an ionized layer. The method comprises the following steps: step 1, determining calculation time and a maximum value of the strength of the medium weft slot; step 2, acquiring solar activity data and geomagnetic activity indexes; 3, calculating the electron density of the background ionized layer when the weft slot structure in the ionized layer is not considered; 4, determining the latitude position of a latitude slot in the ionized layer; 5, calculating the zenith angle of the sun; and step 6, determining the longitude position of the weft slot in the ionized layer. According to the method, the influence of the solar geomagnetic activity on the ionosphere midlatitudinal slot is fully considered, the electron density distribution model considering the midlatitudinal slot structure is constructed according to the midlatitudinal slot electron density spatial-temporal change rule obtained through early-stage data statistical analysis, and the calculation precision of an ionosphere model in a related region is effectively improved.

The invention discloses a high-speed aircraft communication dynamic reconstruction method and system, and the method comprises the steps: building a plasma sheath electron density distribution model through collecting flight state parameters and communication link quality parameters in real time, and calculating plasma characteristic parameters; calculating plasma attenuation based on an electromagnetic wave propagation theory, and predicting future link attenuation by adopting a flight path analysis extrapolation method; judging whether reconstruction is started or not through a multi-dimensional comprehensive triggering criterion fusing link attenuation, a signal-to-noise ratio and a bit error rate; performing joint optimization on communication frequency, transmitting power and a beam pointing angle by adopting a multi-target collaborative optimization method taking communication outage probability minimization and power efficiency maximization as targets; the optimal parameters are issued to execute reconstruction, and closed-loop control is formed; communication parameters can be dynamically adjusted according to the real-time flight state and plasma characteristics, and the communication guarantee capability and energy utilization efficiency of the high-speed aircraft in the plasma sheath environment are remarkably improved.

A method, system, device and medium for inverting electron density based on stimulated electromagnetic radiation characteristics of a hypersonic target wake, the method comprising: signal acquisition, signal processing, peak value screening, and inversion result obtaining; the system, device and medium are used to implement a method for inverting electron density based on stimulated electromagnetic radiation characteristics of a hypersonic target wake; the present application can achieve the effect of inverting the electron density distribution in the plasma without directly contacting the target by analyzing the stimulated electromagnetic radiation signal, can solve the problems of interference of the probe method on the fluid field, temperature sensitivity, limited measurement range and high cost of the laser interference method, has the non-invasive electron density measurement capability, and high sensitivity, and can have high sensitivity inversion effect without disturbing the target fluid.

The application discloses a method for calculating laser propagation distance in a water cloud system based on a plasma-optical field coupling model, comprising the following steps: calculating the number density of liquid droplets of different sizes in different water cloud systems; according to the difference in the sizes of the liquid droplets, calculating the distribution of the electron density of the plasma generated by the laser in a single liquid droplet; according to the change in the electron density distribution, calculating the feedback of the liquid droplet to the optical field and the change in the optical property of the liquid droplet; and through the calculation of the change in the optical property, calculating the nonlinear absorption of the liquid droplet to different laser intensities. Through the consideration of the scattering and absorption of the liquid droplet to the optical field, the propagation distance of the laser in different atmospheric water cloud systems can be obtained.

The invention discloses a method and device for reconstructing vertical electron density distribution by using a TEC map, and the method comprises the steps: obtaining ionosphere frequency-height distribution data from a meridian engineering data center through setting software, and converting the ionosphere frequency-height distribution data into electron density-height distribution data; performing data quality control on the electron density data to obtain quality-controlled electron density data; based on the electron density data after quality control, time-space collaborative TEC data are matched; based on the TEC data, matching space-time collaborative space physical parameters; on the basis of a symbol regression algorithm of genetic programming, calculation is carried out through an empirical formula of station fitting, and TEC physical fitting features are extracted; training a three-hidden-layer full-connection neural network based on the attention mechanism to obtain a trained neural network; and inputting the current time and the set data into the trained neural network for processing to obtain the electron density distribution of the altimeter station position at the current time. According to the invention, real-time reporting can be realized, and the high-precision application requirement is met.

The application discloses a regional ionospheric electron density calculation method and device and computer equipment. The method comprises the following steps: according to all absolute STEC values, all station coordinate information and the coordinate information of the GNSS satellite, the signal ray intercept length through each grid in the to-be-tomographic region is calculated, and a tomographic observation equation is established; according to the position of each grid point, an air-based occultation ionospheric electron density empirical model is used to generate the prior initial value of the electron density of each grid point at the tomographic moment; and the prior initial value of the grid point electron density is iteratively corrected according to the tomographic observation equation, so that the regional ionospheric electron density distribution is obtained. According to the application, the constrained ambiguity float solution is used as the ambiguity initial value of the next epoch, so that the influence of the decimal part of the ambiguity parameter is eliminated, and the initial value of the air-based ionospheric empirical model is greatly accelerated, and the convergence speed is greatly accelerated.

The invention provides a pulse electron gun and a uniform electron beam generation method, and the pulse electron gun comprises a cathode which is used for emitting electrons; the femtosecond laser is used for generating ultra-short pulse laser, and the cathode absorbs the ultra-short pulse laser to excite and form a pulse electron beam; the anode acceleration structure is used for accelerating the pulse electron beam; and the focusing shaping structure is used for carrying out collimation shaping on the accelerated pulse electron beam to obtain a uniform pulse electron beam. The focusing shaping structure is arranged in the pulse electron gun, the transverse electron density distribution of the pulse electron beam is homogenized, beam bunch expansion caused by the space charge effect can be effectively restrained, and the problems that in the prior art, a radio frequency bunching device is large in size and large in size are solved. The equipment cost is high; and the time jitter may be caused by using a radio frequency compression technology.

The application discloses a three-dimensional ionospheric disturbance extraction method, which comprises the following steps: acquiring double-frequency observation data of a research area from a GNSS receiving station; then, calculating STEC from the GNSS double-frequency signal and converting the STEC into dSTEC to highlight the ionospheric disturbance signal; secondly, constructing an observation matrix containing prior ionospheric model information and utilizing an improved three-dimensional tomography algorithm to iteratively correct and gradually approach the real electron density distribution; thirdly, in the iteration process, adopting inverse distance weighted interpolation to correct the pixels not being passed through, so as to ensure the overall smoothness; finally, inputting the dSTEC data into the improved three-dimensional tomography model, obtaining the three-dimensional ionospheric electron density distribution through iterative solution, and comparing the three-dimensional ionospheric electron density distribution with the actual observation data to verify the accuracy of the method. The method can effectively extract the three-dimensional structure of the ionospheric disturbance, improve the reconstruction accuracy and resolution, and provide an effective tool for studying the response of the ionosphere to events such as earthquakes.

The invention discloses an ionosphere prediction method and device based on a white spectrum method and deep learning, and belongs to the technical field of intersection of spatial physics and satellite navigation, and the method comprises the steps: carrying out the preprocessing of multi-source observation data, obtaining time series data, carrying out the white spectrum method analysis of the time series data, and obtaining a disturbance time series; processing the disturbance time sequence to generate a global solar activity level index, a middle and low latitude geomagnetic disturbance index and a polar region geomagnetic disturbance index; the indexes and satellite inversion data serve as input, a deep learning reconstruction model formed by a multi-layer full-connection feedforward neural network is adopted, and ionosphere four-dimensional electron density distribution is output; ionized layer four-dimensional electron density distribution and total electron content observation data serve as input, a space-time prediction model is adopted, and an ionosphere prediction result at the future moment is output. The problems that a traditional spatial index is poor in timeliness and low in resolution and cannot effectively capture the complex time-space characteristics of the ionized layer can be solved.

The invention discloses a plasma electron density distribution microwave diagnosis method based on a particle swarm algorithm, and the method comprises the steps: measuring the phase of an electromagnetic wave without / with plasma through a phase interference principle, obtaining actually-measured phase interference data, calculating an electron density mean value according to the actually-measured phase interference data, and carrying out the calculation of the electron density mean value; generating a plurality of different initial electron density distributions, and then performing multi-order fitting on the initial electron density distributions to obtain an electron density distribution fitting formula; fitting coefficients in the fitting formula serve as particles of a particle swarm algorithm, and an initial population is generated; according to the initial population, plasma electron density distribution is obtained through iterative solution by means of the particle swarm algorithm, phase interference data, corresponding to the electron density distribution, of particles are calculated through a ray tracing method in iteration and serve as analog phase interference data, and the particle fitness is calculated according to the analog phase interference data and actually-measured phase interference data. According to the invention, the electron density distribution diagnosis precision and the resource utilization rate in the strong refraction scene are effectively improved.

The present invention relates to a method for identifying the radial position and amplitude evolution of a fishbone pattern based on a fast-sweep microwave reflectometer, and belongs to the field of plasma diagnosis. The physical principle underlying the method is that a fishbone pattern causes a change in the electron density gradient at its location, and that the electron density gradient is greatest at the location of the fishbone pattern. The present invention radially differentiates the electron density distribution obtained by a fast-sweep microwave reflectometer with high temporal and spatial resolution, and extracts the radial position and value of the maximum electron density gradient in the plasma core region to identify the radial position and amplitude evolution of the fishbone pattern. Compared to conventional methods of identifying the position and amplitude of a fishbone pattern using line integral measurement results from soft X-ray diagnosis, the present invention has higher temporal and spatial resolution, can more accurately identify the radial position and amplitude evolution of a fishbone pattern, is simple to operate, and is reliable and efficient.

The application discloses a GNSS-S radar echo phase correction method based on a spaceborne vertical sounding instrument and a occultation receiver, which utilizes a GNSS-S radar, an occultation receiver and a spaceborne vertical sounding instrument on the same low-orbit satellite platform for cooperative detection. The first electron density profile from the bottom to the top of the ionosphere at a specific position in front of the satellite is acquired by the occultation receiver; when the satellite flies to the position, the second electron density profile from the peak height of the ionosphere to the height of the satellite platform is acquired by the vertical sounding instrument; the second profile is used to calibrate and fuse the first profile to obtain a corrected profile; based on the fused profile, the complete electron density distribution of the downlink and uplink propagation paths of the GNSS-S radar signal is reconstructed, and the total electron content of the paths is calculated respectively; then, the phase error correction amount is calculated according to the total electron content and a phase delay model, and finally, the radar echo is phase compensated to correct the target positioning result. The application can realize accurate correction of the GNSS-S radar phase error caused by the ionosphere.

The invention provides a three-dimensional electron density prediction method and device, equipment, a storage medium and a product, and the method comprises the steps: inputting scattering curve features into a trained electron density prediction model, and obtaining an electron density vector outputted by the electron density prediction model; performing three-dimensional remodeling based on the electron density vector to obtain three-dimensional electron density distribution; wherein the electron density prediction model comprises an input layer, a first hidden layer, a second hidden layer and an output layer; the input layer is used for receiving scattering curve characteristics; the first hidden layer and the second hidden layer are used for carrying out nonlinear mapping and regularization processing from the scattering curve to the electron density on the characteristics of the scattering curve to obtain potential characteristics of the electron density; and the output layer is used for mapping the potential characteristics of the electron density to a final output space and outputting an electron density vector. According to the method, efficient mapping from the scattering curve to the electron density can be realized without manually establishing a physical model, and the three-dimensional electron density distribution can be efficiently and automatically predicted.

The invention relates to a method for calculating the electron density of plasma cloud blocks of an ionized layer in the arctic region. The method comprises the following steps: step 1, determining calculation time and parameters of the plasma cloud blocks; step 2, acquiring solar activity data and geomagnetic activity indexes; 3, calculating background ionized layer electron density distribution when the ionized layer plasma cloud block structure is not considered; and step 4, determining an ionized layer plasma cloud block distribution area. According to the method provided by the invention, the influence of solar geomagnetic activity on the plasma cloud block of the ionized layer is fully considered, the spatial-temporal change rule of the structure is obtained according to early-stage data statistical analysis, the defect of an existing ionized layer model in plasma cloud block description is overcome, and an electron density distribution model considering the plasma cloud block is constructed; the precision of the ionosphere model is improved, the performance of a communication and navigation system is optimized, and the application effect of the ionosphere model in related fields is improved.

The invention discloses a three-dimensional ionosphere disturbance extraction method. The method comprises the following steps: acquiring double-frequency observation data of a research area from a GNSS receiving station; thirdly, STEC is calculated from the GNSS double-frequency signals, and the STEC is converted into dSTEC to highlight ionosphere disturbance signals; secondly, constructing an observation matrix containing prior ionosphere model information, and performing iterative correction by using an improved three-dimensional tomography algorithm to gradually approach real electron density distribution; thirdly, in the iteration process, pixels which are not traversed are corrected through inverse distance weighted interpolation, and the overall smoothness is ensured; and finally, inputting the dSTEC data into the improved three-dimensional chromatography model, obtaining the electron density distribution of the three-dimensional ionosphere through iterative solution, and comparing the electron density distribution with actual observation data to verify the accuracy of the method. According to the method, the three-dimensional structure disturbed by the ionized layer can be effectively extracted, the reconstruction precision and resolution are improved, and an effective tool is provided for researching the response of the ionized layer to events such as earthquakes.

The application relates to a method for removing low-concentration ammonia nitrogen by catalytic oxidation, and relates to a method for removing low-concentration ammonia nitrogen by catalytic oxidation. The application aims to solve the technical problems of the existing ammonia nitrogen removal method, such as strict reaction conditions, high energy consumption and cost, and low practical application feasibility. The porous carbon-nitrogen-coated FeMn bimetallic catalyst prepared by the application has a large specific surface area and a porous structure, which is helpful for the rapid occurrence of a catalytic reaction. Meanwhile, the Fe / Mn bimetal and the nitrogen element doping can adjust the electronic structure and the electron density distribution of the material, greatly increase the number of active sites, and improve the catalytic activity. The porous carbon structure on the surface of the material provides a stable chemical structure for the catalyst, which is helpful for the material to resist corrosion and change under different reaction conditions, so that the material can be used repeatedly. The ammonia nitrogen removal rate is more than 90% within 30 minutes.

The invention provides a laminated imaging method based on an X-ray tomography device, which is applied to the crossing field of X-ray microscopic imaging and integrated circuit testing, and comprises the following steps: constructing the X-ray tomography device, scanning a sample based on a Fermat spiral path, and obtaining an original diffraction pattern of the sample; performing sub-pixel displacement correction on the original diffraction pattern; performing low-rank constraint frame fusion on the original diffraction pattern based on the diffraction pattern sequence after grouping correction and a displacement parameter for frame fusion to obtain a synthetic diffraction pattern; performing mixed state lamination reconstruction on the synthesized diffraction pattern to obtain an electron density distribution diagram and a three-dimensional electron density distribution model; based on a three-dimensional electron density distribution model, a holographic correlation classification graph is obtained through density threshold segmentation and a random forest classifier, a Fresnel zone plate is adopted to generate a focusing probe, and high-precision phase recovery is realized through time-sharing acquisition of multiple frames of low-exposure diffraction graphs and superposition of diffraction data in a Fermat spiral path.

The application relates to a plasma flow field electron density distribution electromagnetic correction method, and relates to the electromagnetic correction field, and comprises the following steps: simulating the electron density of a model surface, and taking the simulated flow field electron density distribution as a basic distribution; inverting a correction function through the RCS measurement result of an observation point; expanding the correction function at the original point into a Taylor series to obtain the correction function; multiplying the correction function and the basic distribution at any position to obtain the correction value of the electron density at the any position; and the optimal individual screened out by a genetic algorithm is the inversion correction result, so that the simulation result of the plasma flow field electron density distribution can be corrected after the known target shape, the simulation result of the plasma flow field electron density distribution, the change amount of the RCS of the target within a limited azimuth angle and a limited frequency point after being affected by the plasma, and the accuracy of the simulation result of the plasma electron density is further improved.