51 results about "Bessel function" patented technology

The invention discloses a data processing method and system for micro-motion detection array station distribution, and relates to the technical field of micro-motion detection, and the method comprises the steps: according to the actually measured starting point coordinates and the azimuth angle of a measuring line, setting the measuring point distance, and the radius and number of nested triangle circumcircles, generating field station coordinates in batches; collecting and preprocessing station waveform data; calculating a spatial autocorrelation coefficient of any center station and a non-center station; dBSCAN clustering is carried out based on the station distance; performing spatial averaging on the spatial autocorrelation coefficient according to a clustering result; fitting the averaged spatial autocorrelation coefficient and a zero-order Bessel function to obtain a frequency dispersion spectrum, picking up a surface wave phase velocity in the frequency dispersion spectrum, and calculating an apparent shear wave velocity; inverting the shear wave velocity of the waveform data by adopting a self-adaptive gradient inversion strategy; and generating a velocity comprehensive profile of a depth domain and a frequency domain according to the surface wave phase velocity, the apparent shear wave velocity and the inverted shear wave velocity. The invention provides a new method for station distribution to data processing for micro-motion detection.

The invention relates to the technical field of fault prediction and diagnosis systems, in particular to a multi-sensor fusion air energy heat pump fault prediction and diagnosis system, which is characterized in that a data acquisition module is used for acquiring a multi-dimensional data set in the operation process of an air energy heat pump; the data preprocessing module generates a topological variation matrix based on the data set; the fault diagnosis module comprises a feature extraction sub-module, a feature compression sub-module, a fault classification sub-module, a mode matching sub-module and a fault backtracking sub-module which are connected in sequence, and a fault classification result, an optimal matching mode and a fault reason are obtained based on progressive processing of a topological variation matrix; the fault prediction module predicts a future fault type and occurrence time based on the fault diagnosis result; the decision-making module generates an optimization strategy according to a fault prediction result, the accuracy of the system on pattern matching is remarkably improved through combination of modulus operation and an Euler function, and meanwhile, the depth and reliability of fault reason analysis are further enhanced through application of a Bessel function in fault backtracking.

The invention provides a phase generated carrier demodulation method based on two-parameter estimation. The method comprises the following steps of: firstly, realizing estimation of a C value by extracting an amplitude ratio of a carrier frequency multiplication component in an interference signal frequency spectrum and combining a Bessel function characteristic; then, carrying out operation processing by utilizing a first frequency multiplication signal and a second frequency multiplication signal to extract carrier phase delay theta c; and finally, eliminating the influence through dynamic phase compensation. According to the demodulation method provided by the invention, the nonlinear drift of the modulation depth parameter C and the synchronous estimation and compensation of the carrier phase disturbance signal theta c can be realized, the cross interference error in the traditional demodulation system is effectively inhibited, the phase demodulation robustness is remarkably improved, and the harmonic nonlinear distortion is effectively inhibited.

The invention discloses a sine frequency modulation harmonic error compensation method based on Bessel function modulation characteristics, and relates to the technical field of sine frequency modulation nonlinear parameter compensation and high-precision measurement of target absolute distance based on multi-wavelength interference. The problem that the constant phase demodulation precision is insufficient due to the fact that carrier harmonic waves, accompanying amplitude modulation and modulation depth errors cannot be effectively suppressed due to laser modulation nonlinearity in existing sine frequency modulation distance measurement is solved. According to the method, after sine frequency modulation interference signals are collected, high-pass filtering is carried out to remove low-frequency components, Hilbert transform is carried out to remove envelope suppression associated amplitude modulation, window function frequency mixing is carried out to extract modulation depth, a matched carrier containing second harmonics is constructed, and frequency modulation harmonic parameter optimization is achieved through baseband amplitude maximization. And finally, carrying out orthogonal demodulation on the compensated interference signal to obtain a high-precision constant phase. The method is suitable for high-precision multi-wavelength interference ranging, precision displacement measurement and optical metering systems.

The invention discloses a microwave antenna with a low side lobe. The microwave antenna comprises a main reflecting surface, a feed source and a surrounding edge, wherein the main reflecting surface is of a rotating paraboloid structure, and a feed source is arranged at the focus of the main reflecting surface; the feed source comprises a radiation source, an auxiliary reflecting surface, a circular waveguide and a dielectric ring arranged on the splashing plate; the surrounding edge is arranged around the edge of the main reflecting surface and is used for absorbing signals exceeding the receiving range of the main reflecting surface; geometric parameters of the dielectric ring are configured to enable a feed source directional diagram to conform to improved generalized Taylor displacement distribution, an expression of the improved generalized Taylor displacement distribution is # imgabs0 #, rb is a center shielding radius, B1 is a constant larger than 0.45, J0 is a value of a first zero point of a zeroth-order Bessel function, and the feed source directional diagram is adjusted by adjusting the geometric parameters of the dielectric ring on the basis of the expression. And the microwave antenna can achieve the effect of low side lobe.

This invention discloses a method and system for measuring the frequency response of an electro-optic modulator based on a spectral analyzer. The system includes a laser, a 95:5 single-mode fiber splitter, an optical power meter, an electro-optic modulator, a control power supply, an RF signal generator, and a spectral analyzer. The measurement method includes the following steps: calculating a calibration factor to correct optical power drift through optical path splitting, driving the modulator by applying several discrete single-frequency RF points, and measuring the carrier power P0(f) using the spectral analyzer. i ) and the first-order sideband power P1(f i ), and determined by the power ratio R(f) i )=10 (P1‑P0) / 10 Combining the Jacobi–Anger expansion / Bessel function relation, the phase modulation index β(f) is solved by inverse solution. i Then, the phase transfer function H(f) at each frequency point is calculated and fitted. i The continuous frequency response S of the modulator is obtained. 21 This invention simplifies the testing process, reduces reliance on high-speed photodetectors and vector network analyzers, and enables high-precision electro-optic response testing of electro-optic modulators at high frequencies.

According to the method, a surface gravity wave and inner interface wave velocity potential field is analyzed into a product form of a vertical characteristic item and a horizontal diffraction field, and dimensionality reduction solution of a three-dimensional wave problem is realized; a vertical characteristic function orthogonal system meeting free liquid level, seabed boundary and interface coupling conditions is constructed, horizontal diffraction potential is decomposed into an incident field, a local column and an adjacent column scattering effect, and a Bessel function addition theorem is applied to construct a closed linear equation set of a multi-column interference field; establishing an extended dispersion equation containing density spring layer parameters, and revealing a modulation rule of layered strength on complex wave propagation characteristics; and finally, through tensor product coupling of a vertical mode and a horizontal diffraction field, constructing a full-three-dimensional diffraction velocity potential analytical solution, synthesizing a cross-layer pressure field integral by adopting a domain decomposition technology, and establishing a multi-column array generalized wave excitation force forecasting model. According to the method, efficient analytical calculation of the wave load of the multi-column system in the layered fluid is innovatively achieved.

The application discloses a non-circular sparse array DOA estimation performance evaluation method based on information theory, which comprises the following steps: firstly, a multi-dimensional probability density function (PDF) of a received signal is constructed, a joint PDF of the received signal and DOA and a DOA posteriori PDF are derived through information theory, and a system DOA information quantity is obtained by simplifying the DOA posteriori PDF with a Bessel function; then, a DOA posteriori PDF of given noise is derived, and a DOA information approximate upper limit is obtained by simplifying the DOA posteriori PDF with a Taylor expansion; finally, a DOA estimation performance index entropy error is obtained by using the posteriori differential entropy; the application builds a non-circular sparse array system DOA information theory framework based on information theory, in actual signal processing, the entropy error of a parameter can be calculated only by estimating the posteriori PDF of the parameter, and a performance limit independent of an algorithm is provided; in addition, it is found through simulation that the DOA information quantity approaches the DOA information upper limit under a high signal-to-noise ratio, and the entropy error approaches the Cramer-Rao limit, thereby verifying the rationality of the index.

The invention discloses a single-stage gear parametrically-excited vibration response frequency spectrum prediction method based on modulation feedback, and the method comprises the steps: building a single-degree-of-freedom kinetic equation containing time-varying meshing stiffness based on the Newton second law, and solving a main oscillation frequency through employing a modulation feedback theory and a trigonometric series approximation method; constructing a quantitative prediction model of excitation parameters and dominant side frequency orders on the basis of a first-class Bessel function, and solving system response by applying a four-order Runge-Kutta method in combination with fast Fourier transformation to verify the prediction model; a parameter sensitivity analysis framework is established through a harmonic coefficient method, and the influence of excitation parameters on the main oscillation frequency and the side frequency amplitude ratio is quantified.

The invention belongs to the technical field of ink-jet printing, provides a Bezier curve-based pulse generation method, device and equipment and a medium, and solves the technical problem that the acceleration of an acceleration section and a deceleration section of a printing trolley in the prior art is a fixed value, so that the printing trolley cannot run stably. The method comprises the following steps: acquiring an actual printing trolley speed curve according to a preset printing trolley speed curve, and acquiring acceleration and deceleration coefficients at each moment according to a third-order Bezier function corresponding to the actual printing trolley speed curve; according to the acceleration and deceleration coefficient at each moment, acquiring the frequency of a driving pulse at each moment; and generating the driving pulse according to the frequency of the driving pulse at each moment. The printing trolley can run stably, and the problems of liquid level warning misinformation, overall printer displacement and the like caused by machine shaking are solved.

The invention discloses a pile body torsion dynamic response analysis method and system based on a virtual soil pile in the technical field of pile foundation dynamic response analysis. The method comprises the following steps: constructing a total energy function of the pile-soil coupling system; variation is conducted on the total energy function of the pile-soil coupling system on the basis of the variation principle, and a pile periphery soil body radial control function in a general solution form and a Bessel function form of a pile body control differential equation is obtained; according to the general solution form of the pile body control differential equation and the built-in boundary conditions of the bottom of the virtual soil pile section, an equivalent complex impedance function of the top of the virtual soil pile section is constructed; according to the continuity condition and the boundary condition of the pile body and the equivalent complex impedance function of the top of the virtual soil pile section, a system response linear algebraic equation set is constructed; and iteratively updating the control variable of each layer of soil body to obtain the converged control variable of each layer of soil body, further calculating a torsion power response value at the pile top, and obtaining a torsion impedance function of the pile body based on the torsion power response value at the pile top.

The invention discloses a technical scheme of a laser power detection rapid response realization method, and the method comprises the steps: describing a laser-induced thermal voltage time response characteristic curve through employing a Bessel function when laser-induced thermal voltage is measured through employing a thermopile temperature difference sensing principle based on a plane heat conduction process; and predicting a thermal voltage steady-state value in advance and converting the thermal voltage steady-state value into a laser power value. Differential calculation is used, the starting time of a thermoelectric signal caused by laser input does not need to be preset, the rising edge and the falling edge of a sensing signal can be automatically and continuously detected in an unattended mode, the convenience and operability of laser power detection are greatly improved, the thermal voltage steady-state value can be obtained through calculation only by accurately collecting 4-6 pieces of thermal voltage data, and the detection accuracy is improved. Therefore, the thermoelectric response time is shortened from conventional 9s to 4s, the steady-state time is shortened from 30s to 6s, and the error of the steady-state value is less than 2%.

The invention discloses a novel modal shape function construction method suitable for a variable cross-section flexible structure, and the method comprises the following steps: firstly, building a linear kinetic equation of a flexible wing based on an Euler-Bernoulli beam theory and a Lagrange principle; secondly, geometric and physical parameters in the equation are normalized through dimensionless variable substitution, and the coupling relation between different variables is simplified; secondly, formalizing the solution into a linear combination of a first type of Bessel function and a second type of Bessel function by adopting a special function expansion method so as to ensure that boundary conditions are met and effectively reflect the influence of section change on modal characteristics; and finally, solving the inherent frequency and a modal shape function by constructing a novel modal shape function. According to the method, iteration and approximate truncation are not needed, the inherent frequency and the modal shape can be rapidly and accurately calculated, the calculation efficiency is remarkably improved, high calculation precision is guaranteed, and the method is suitable for efficient dynamic analysis of a complex structure.

The invention discloses a micro-motion exploration frequency dispersion curve extraction method, device and medium, and relates to the technical field of micro-motion exploration, and the method comprises the following steps: S1, calculating the average cross-correlation spectrum of each station pair according to the recorded data of a plurality of stations in an observation array; s2, aiming at the average cross-correlation spectrum of each station pair, identifying a first intersection point frequency of the average cross-correlation spectrum and a frequency axis; s3, based on the first intersection point frequency, performing piecewise fitting on the average cross-correlation spectrum to extract a phase velocity: for a frequency band not greater than the first intersection point frequency, performing fitting by adopting a zero-order Bessel function J0; and for a frequency band of which the frequency is greater than the frequency of the first intersection point, performing fitting by adopting a first-class zero-order Hankel function H0 (1). In a single method, the contradiction of artifact interference in a high frequency band and insufficient detection depth in a low frequency band in the prior art is overcome at the same time, the accuracy and reliability of frequency dispersion curve extraction under the sparse array condition are improved, and the detection depth of micro-motion exploration is effectively expanded.

The invention relates to the technical field of geodetic parameter inversion, and discloses a horizontal hierarchical geodetic parameter inversion method, system, equipment and medium, and the method comprises the steps: constructing an inversion objective function according to an apparent resistivity prediction function and an apparent resistivity measurement value which are constructed through employing a kernel function and a first-class zero-order Bessel function; and representing the kernel function by adopting an odd polynomial and an even polynomial, representing the odd polynomial and the even polynomial on the basis of an adjacent layered soil resistivity change rate set and a layered thickness sum set obtained by adopting a permutation and combination algorithm, and then performing partial derivative calculation, according to the obtained first partial derivative relational expression and the second partial derivative relational expression, a complex mirror image method is adopted to obtain a third partial derivative relational expression of the inversion target function to the soil resistivity and a fourth partial derivative relational expression of the inversion target function to the layering thickness; and carrying out horizontal layered geodetic parameter inversion by adopting a trust region algorithm to obtain an inversion result. According to the method provided by the invention, the accuracy and reliability of a horizontal layered geodetic parameter inversion result are improved.

The application discloses a nonlinear phase error compensation method of an optical fiber demodulator, and relates to the technical field of phase error compensation.The method comprises the following steps: synchronously collecting interference signals output by a photoelectric detector by an analog-to-digital converter, performing low-pass filtering and amplitude extraction on the digitized interference sequence by using a carrier wave and a twice-frequency orthogonal reference signal, calculating a current amplitude ratio according to a fundamental wave amplitude and a second harmonic amplitude, estimating a current actual phase modulation depth by using a Bessel function relationship, and generating an error signal by a digital PID.The application adjusts a driving voltage amplitude in real time by using an analog voltage control programmable high-voltage driving source, thereby guaranteeing the safety monitoring of a high-pressure gas pipeline and solving the problem of system failure caused by phase modulation depth drift in long-distance oil and gas pipeline network distributed optical fiber sensing in the prior art.

The invention provides a rapid calculation and compensation method for influences of rainfall on visible light-near infrared band optical communication, and aims to solve the problems that a traditional Mie scattering calculation method depends on Bessel function, continued fraction recursion and other methods, the programming implementation technology is complex, the calculation speed is low, and numerical instability is prone to occurring. And rapid and efficient requirements of related research are difficult to meet. According to the rapid calculation and compensation method for the influence of rainfall on visible light-near infrared band optical communication, an extinction coefficient rapid calculation model, a scattering coefficient rapid calculation model and an asymmetry factor rapid calculation model are established; according to the method, the Mie scattering optical parameters of rainfall of three rainfall types and any rainfall intensity in the visible light-near infrared band can be rapidly and stably calculated, the calculation result is rapidly output in real time on the basis of ensuring the calculation accuracy, and the method can be widely applied to the optical communication compensation technology in the fields of laser communication, automatic driving and the like.

The invention discloses a carbonate rock gas reservoir productivity prediction method and device. The method comprises the following steps: establishing a first seepage equation of a quasi-steady-state seepage mode and a second seepage equation of an unsteady-state seepage mode in the carbonate rock gas reservoir in combination with a non-darcy effect and a stress sensitive effect; performing dimensionless processing and Laplace transformation to obtain a first comprehensive control differential equation and a second comprehensive control differential equation; performing Fourier cosine transform, combining a Bessel function general solution, and obtaining a pressure distribution solution in the pull-type space through point source and line source functions; a real space quasi-pressure solution is obtained through inversion according to the pressure distribution solution in the pull-type space, and then a yield prediction model under the fixed flowing bottomhole pressure condition is obtained; and based on the established productivity prediction model, predicting the yield of the target well according to the fixed bottomhole flowing pressure of the target well in the carbonate rock gas reservoir. According to the method, complex relevance among triple media of the carbonate gas reservoir is fully considered, and reasonable yield prediction is achieved.

The invention provides a double-interferometer system demodulation method and device, and the method comprises the steps: generating laser through a modulation laser, and inputting the laser into a signal interferometer and a reference interferometer, determining a first orthogonal signal and a second orthogonal signal corresponding to the signal interferometer, and a third orthogonal signal and a fourth orthogonal signal corresponding to the reference interferometer; the arm length differences of the signal interferometer and the reference interferometer are equal; solving a first modulation depth of the signal interferometer and a second modulation depth of the reference interferometer through an ellipse fitting algorithm, calculating Bessel function values of the first modulation depth and the second modulation depth, and obtaining an orthogonal signal without the modulation depth according to the orthogonal signal; and constructing a product sum-difference formula according to the orthogonal signal of which the modulation depth is eliminated, and obtaining an optical phase signal of which the noise is eliminated through arc tangent operation.

The invention belongs to the technical field of electric automobiles, and particularly relates to a design method of a cam rotary drum type gear shifting executing mechanism. The method comprises the steps that S1, the relation between the angular speed of a motor and the rotating arc length of a cam is determined; s2, designing an optimization method for reducing impact at a gear shifting corner by calculating an arc equation at the corner and a transverse acceleration; s3, optimizing a path at a corner through a Bessel function; and determining two optimization methods, namely a Bezier function optimization method for changing the corner position of the groove and a Bezier function optimization method for changing the corner position of the groove according to the selected control points forming the Bezier curve and different optimized positions. According to the method, the connecting part between the inclined area and the flat area of the surface groove of the cam drum is optimized, the impact generated when the shifting fork pin passes through the corner in the gear engaging process is reduced, and the problems that impact is generated and gear shifting is not smooth when the shifting fork pin passes through the corner of the surface groove of the cam drum are solved.

The invention relates to the technical field of satellite system engineering and micro-vibration suppression, in particular to a method for quickly constructing and optimizing an optical remote sensing satellite micro-vibration suppression index system, which comprises the following steps of: acquiring an imaging quality index threshold, a system static modulation transfer function value, a structure transfer function data set and a flywheel disturbance source characteristic data set; constructing a system-level frequency domain response model based on a frequency domain transfer function chain, calculating a modulation transfer function attenuation factor caused by high-frequency micro-vibration by utilizing a zero-order Bessel function and a time delay integral smoothing function, and establishing a reverse design inequality to solve an allowable maximum disturbance force upper limit curve of the flywheel under different rotating speed frequencies; and vibration isolation device design parameters or flywheel model selection strategies are output through comparison with a flywheel actual measurement disturbance spectrum. According to the method, the problems that existing time domain simulation calculation is low in efficiency and lacks parameter inverse solution capacity are solved, millisecond-level rapid evaluation and direct design guidance are achieved, and the overall satellite scheme argumentation period is remarkably shortened.

The invention discloses a demodulation stability improving method and system based on primary ellipse fitting, and belongs to the technical field of phase demodulation. According to the invention, based on a one-time ellipse fitting technology, an additional low-frequency sinusoidal signal is superposed in laser modulation, so that an interference signal generates a complete elliptical orbit, and an ellipse fitting algorithm is utilized to extract a direct current amount, an alternating current amplitude and a phase difference of fitting parameters in advance. A modulation depth value C is inquired and matched through fitting parameters in combination with a Bessel function table, accurate calibration of key parameters is achieved, then the phase difference of non-strict orthogonal signals is corrected, direct current is removed, and demodulation distortion caused by phase deviation is eliminated. Meanwhile, an intensity disturbance signal B containing light intensity fluctuation and circuit noise is calculated in real time based on the modulation depth value C and the fitting parameter, and is dynamically removed in the demodulation process, so that the intensity disturbance signal B is prevented from being superposed to a sensing signal, and the stability of a demodulation amplitude value is remarkably improved.

The invention relates to the technical field of transformer station grounding grid evaluation, and provides a dynamic evaluation method and system for power station grounding short circuit transfer potential, and the method comprises the steps: employing a Wenner quadrupole method to measure the apparent resistivity of soil, and constructing an apparent resistivity-depth change curve; reversely deducing the resistivity and the thickness of each layer of soil by adopting an inversion algorithm and combining an analysis kernel function and Bessel function expansion, so as to obtain soil layering parameters of a multi-layer and non-uniform structure; and obtaining a short-circuit current, a grounding grid structure and the obtained soil layering parameters, and obtaining a grounding short-circuit transfer potential of the grounding grid of the to-be-evaluated power station by adopting coupling simulation analysis mixed with a finite element method and a moment method. According to the method, the real soil model is constructed by combining the Wenner quadrupole method measurement and the inversion algorithm, and the finite element and moment method coupling simulation is introduced, so that the grounding short circuit transfer potential is accurately evaluated, and the prediction precision and the system safety under the complex geological condition are remarkably improved.

The application discloses an ocean drilling stratum structure detection method and related equipment, and the method comprises the following steps: obtaining early data of a candidate area, and collecting seabed background noise of the candidate area by using a concentric circular ring array to obtain original noise data; preprocessing and segmenting the original noise data to obtain segmented noise data; performing azimuth weighted average and Bessel function fitting on the segmented noise data based on a noise main direction of the concentric circular ring array to obtain a target dispersion curve; taking the target dispersion curve as a constraint, performing nonlinear inversion by using a genetic algorithm to obtain a transverse wave velocity structure model; performing joint verification based on the transverse wave velocity structure model and the early data, and screening drilling hole positions according to a judgment result of the joint verification. The application provides independent, quantitative and traceable geophysical basis for pre-drilling site selection, can effectively reduce drilling risks, and can be widely applied to the technical field of seismic structure detection.

The invention discloses a vehicle adaptive cruise method based on vehicle speed planning, which comprises the following steps that: a vehicle receives a satellite signal to determine a current position, and obtains the altitude and speed limit data of a front road; an n-order Bezier function is constructed, and a vehicle speed curve of the vehicle speed relative to the road position is generated through the Bezier function; an evaluation function of the vehicle speed curve is constructed, and constraints are established; a wild horse optimization algorithm is improved, and Gaussian distribution is introduced to generate an initial population and an individual position updating strategy based on Levy flight so as to improve the global search capability and the convergence speed; inputting the Bezier function and the evaluation function into an improved wild horse optimization algorithm, and finally outputting an optimal cruise speed curve; based on the optimal cruise speed curve, the conversion relation between fuel energy and electric energy is determined by using an ECMS global optimization strategy and introducing an equivalent factor, a global optimal control strategy can be obtained by minimizing a Hamilton value, then an optimal control method of an engine and a motor at each moment is obtained, and the engine is controlled.

The present invention discloses a data processing method and system for the layout of a microseismic detection array, which relates to the technical field of microseismic detection. The method includes: setting the measuring point distance, the radius and quantity of the circumscribed circles of nested triangles according to the measured starting point coordinates and the azimuth angle of the survey line, and batch generating the coordinates of field stations; collecting the waveform data of the stations and preprocessing it; calculating the spatial autocorrelation coefficient between any central station and non-central stations; performing DBSCAN clustering based on the station distances; performing spatial averaging on the spatial autocorrelation coefficient according to the clustering results; fitting the averaged spatial autocorrelation coefficient with the zero-order Bessel function to obtain the dispersion spectrum, picking up the surface wave phase velocity in the dispersion spectrum, and calculating the apparent shear wave velocity; adopting an adaptive gradient inversion strategy to invert the shear wave velocity of the waveform data; generating a velocity comprehensive profile in the depth domain and frequency domain according to the surface wave phase velocity, the apparent shear wave velocity, and the inverted shear wave velocity. The present invention provides a new method for microseismic detection from station layout to data processing.

This invention discloses a method and related equipment for detecting geological structures during ocean drilling. The method includes: acquiring preliminary data of a candidate area and collecting seabed background noise in the candidate area using a concentric ring array to obtain raw noise data; preprocessing and segmenting the raw noise data to obtain segmented noise data; performing azimuth-weighted averaging and Bessel function fitting on the segmented noise data based on the principal noise direction of the concentric ring array to obtain a target dispersion curve; using the target dispersion curve as a constraint, performing nonlinear inversion using a genetic algorithm to obtain a shear wave velocity structure model; jointly verifying the shear wave velocity structure model with the preliminary data, and selecting drilling sites based on the joint verification results. This invention provides independent, quantitative, and traceable geophysical evidence for pre-drilling site selection, effectively reducing drilling risks, and can be widely applied in the field of seismic structure detection technology.

The invention discloses a layered medium electromagnetic field calculation method and device, electronic equipment and a medium. The method comprises the following steps: establishing a Bessel function integral expression of a uniform layered medium electromagnetic field; segmenting an integral region according to the distance from an emission source to a receiving point, and further carrying out segmented discretization on a Bessel function; performing quadratic interpolation on the Bessel function integral expression of each integral unit through a shape function to obtain an integral expression corresponding to the integral unit; an integral expression corresponding to each integral unit is calculated, and an integral result of the layered medium electromagnetic field is obtained through accumulation calculation. The method is suitable for high-precision calculation of a complex layered electromagnetic field, and solves the problem of low universality and precision of an algorithm in the prior art.

A three-dimensional imaging method of a vortex electromagnetic wave radar based on a bistatic mode. Step 1: A rectangular coordinate system is constructed with the center of the UCA as the origin. Then, two independent transmitting array elements are set at different positions on the positive X-axis direction, and two transceiver channels TR1 and TR2 are respectively formed with the UCA receiving unit. Step 2: The echo signals of the two dual transceiver channels TR1 and TR2 are respectively subjected to matched filtering in the range dimension to reconstruct the one-dimensional range image of the target. Step 3: The Hilbert transform is respectively used for the two dual transceiver channels TR1 and TR2 in the mode number domain to eliminate the influence of the square term of the Bessel function, and then the FFT transform is used to reconstruct the one-dimensional azimuth image. Step 4: The ranges obtained from TR1 and TR2 and the azimuth are combined to solve the true range and elevation angle of the target, and the three-dimensional coordinates of the target space are reconstructed. It can achieve high resolution for small elevation angle targets without increasing the complexity of the array structure, and the computational amount of the method is significantly better than that of the MUSIC algorithm.

The invention discloses a rapid calculation method and system for a grid-connected current THD of a high-voltage direct-hanging energy storage system, and belongs to the technical field of high-voltage direct-hanging energy storage systems. The method aims at solving the problems that existing THD calculation depends on multi-power-frequency period sampling, is slow in updating and cannot adapt to a scene with inconsistent modulation signals of in-phase sub-modules. The method comprises the following steps: sampling to obtain system parameters and modulation signals; calculating modulation signal adjustment quantity amplitude and additional fundamental frequency voltage; a final modulation signal is obtained through alpha-beta axis vector superposition; calculating a harmonic voltage amplitude based on a carrier phase-shifting modulation model and a Bessel function; deriving a harmonic current amplitude and a fundamental current amplitude, and solving THD; and the harmonic calculation frequency is dynamically adjusted through error verification. Only control variables are used for calculation, the calculation speed is high, the precision is high, the relative error is smaller than or equal to 5%, the DSP burden is reduced, control strategy adjustment can be rapidly supported, and stable operation of a power grid is guaranteed.