Fast prediction method and device for sound scattering characteristics of complex target under limited beam incidence

Abstract

The application relates to a fast prediction method and device for sound scattering characteristics of a complex target under limited beam incidence, which comprises the following steps: constructing a three-dimensional geometric model of the complex target, and dividing the surface into a triangular facet grid; based on the set incidence parameters of the limited beam, calculating the included angle between the direction vector of the triangular facet to the sound source and the beam direction vector, and screening the illuminated facets in response to the included angle being less than half of the beam angle; calculating the scattering contribution of all the screened illuminated facets in the frequency domain, coherently superimposing the scattering contribution, obtaining the frequency domain scattering sound field of the complex target under the limited beam incidence, and interpolating the frequency domain scattering sound field in the wideband frequency range to obtain the wideband scattering response, and calculating the wideband time domain scattering waveform of the complex target under the limited beam incidence. The application can be applied to the near-field incidence condition of the limited beam, can consider the calculation accuracy and efficiency, and can process the underwater target sound scattering characteristics of the complex target geometric shape.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic engineering technology, and in particular to a method and apparatus for rapid prediction of the acoustic scattering characteristics of complex targets under finite beam incidence. Background Technology

[0002] In the field of active sonar detection technology, accurately predicting the acoustic scattering characteristics of underwater targets is fundamental to target identification, detection system performance evaluation, and underwater combat environment simulation. For a long time, target acoustic scattering models have primarily been established based on the far-field plane wave assumption. This assumption assumes that the distance between the sound source and the target is much greater than the wavelength of the sound wave, the incident sound field can be approximated as an omnidirectional plane wave, and the target scattered sound field is independent of distance. Under this assumption, techniques such as physical optics approximation, plate element method, and bright spot model have been widely used to estimate target intensity. However, with the widespread application of underwater unmanned vehicles, torpedoes, and new types of underwater weapons, the modern underwater combat environment has shifted from traditional large-scale search and detection to near-field precision guidance and rapid response strikes. This has led to a significant reduction in the distance between the sound source and the target, with targets frequently located in the near-field region of the sound source. To improve spatial resolution and suppress reverberation interference, practical detection systems often employ sound sources with strict spatial directivity, forming a finite sound beam with limited angle and concentrated energy. Under such finite beam incidence conditions, the target scattered sound field depends not only on the target's own geometry, but also strongly on factors such as the spatial distribution of the incident beam, the beam opening angle, the relative distance between the sound source and the target, and the azimuth angle. It exhibits significant distance dependence and azimuth sensitivity. Traditional modeling methods based on far-field plane waves can no longer accurately describe this type of physical process.

[0003] Currently, research on acoustic scattering under finite beam incidence conditions mainly focuses on ultrasonic testing, and often involves analytical calculations for regular geometries such as spheres, infinitely long cylinders, or flat plates. The theoretical results are difficult to directly apply to actual targets such as underwater vehicles and submarines with complex shapes and multiple scales and curvatures. For complex targets, while the traditional plate-element method can discretize complex geometries using surface elements, its theoretical derivation is strictly based on the plane wave incidence assumption and lacks the ability to characterize the sound field distribution characteristics of finite beams. Methods based on iterative physical acoustics can consider blocking effects and multiple scattering, but the computational load increases dramatically with target complexity, making it difficult to meet the real-time requirements of engineering. Furthermore, under broadband signal incidence conditions, using traditional frequency-point-by-frequency calculation methods to obtain time-domain echo characteristics is extremely time-consuming, failing to meet the stringent speed requirements of near-field dynamic measurement and characteristic analysis applications. Summary of the Invention

[0004] Therefore, it is necessary to address the problems of failure of the far-field assumption, difficulty in accurately defining the illuminated area of ​​the finite beam, and low computational efficiency of broadband signals. A rapid prediction method and apparatus for the acoustic scattering characteristics of complex underwater targets under finite beam incidence conditions should be provided, which can be applied to finite beam near-field incidence conditions, balance computational accuracy and efficiency, and handle the acoustic scattering characteristics of underwater targets with complex geometries.

[0005] This invention provides a rapid prediction method for the acoustic scattering characteristics of complex targets under finite beam incidence, the method comprising: A three-dimensional geometric model of a complex target is constructed, and the surface of the three-dimensional geometric model is divided into a triangular mesh, the maximum size of which is set according to the wavelength of the incident sound wave. Based on the incident parameters of the finite beam, including the sound source location, beam direction vector, and beam angle, for each triangular element in the triangular element grid, the angle between the direction vector of the triangular element to the sound source and the beam direction vector is calculated, and in response to the angle being less than half of the beam angle, the triangular element is selected as an element illuminated by the finite beam. Using the physical acoustic block element method, the scattering contribution of all selected illuminated surface elements in the frequency domain is calculated, and the scattering contributions of all illuminated surface elements are coherently superimposed to obtain the frequency domain scattering sound field of the complex target under the incident finite beam. Using the Chebyshev series uniform approximation theory, the frequency-domain scattered sound field is interpolated and approximated over a wide frequency range to obtain a wide-bandgap scattering response. The wide-bandgap time-domain scattering waveform of the complex target under finite beam incident is then calculated using inverse Fourier transform.

[0006] In one embodiment, dividing the surface of the three-dimensional geometric model into a triangular mesh specifically involves: The target surface is divided into triangular elements according to the requirement that the maximum size does not exceed one-quarter of the incident sound wave wavelength.

[0007] In one embodiment, calculating the angle between the direction vector of the triangular element to the sound source and the beam direction vector, and filtering the triangular element as an element illuminated by the finite beam in response to the angle being less than half of the beam angle, includes: Calculate the vector from the target surface element to the sound source. , The coordinates of the target surface source, The coordinates of the sound source; Calculate the unit vector from the target surface element to the sound source. ,in ; Obtain the unit vector of the transmitted beam acoustic axis direction ; Calculate the included angle cosine value ; Determine if it satisfies ,in The beam angle is half of the beam angle, i.e., the beam half angle. If this condition is met, the triangular element is determined to be located within the finite beam and illuminated.

[0008] In one embodiment, the physical acoustic slab element method is used to calculate the scattering contribution of all selected illuminated surface elements in the frequency domain, specifically as follows: Based on the high-frequency assumption, the boundary conditions on the illuminated surface element are satisfied. and The sound field was calculated using Rayleigh Kirchhoff's integral formula, where the scattering contribution of each surface element was determined. Let be the incident wave potential function. Let be the potential function of the scattered wave. For the surface element normal direction.

[0009] In one embodiment, for a combined transceiver sound source and receiver, the frequency domain scattering contribution of each illuminated surface element is based on an integral. Calculation, where The expression form is: , In the formula, It is a vector from any point on the surface element to a preset reference point. It is the unit normal vector of this surface element. It is the unit vector from the reference point to the far-field receiving point. It is the wave number. This represents the illuminated triangular facet region.

[0010] In one embodiment, based on the integral Calculate the echo intensity of the complex target under the finite beam incident light. and far-field target intensity The calculation formula is: , , In the formula, The distance between the sound source or receiver and the reference point. For wave number, The distance from the sound source to the reference point. The distance from the reference point to the receiver. It is the imaginary unit.

[0011] In one embodiment, the method of interpolating and approximating the frequency-domain scattered sound field over a wide frequency range using Chebyshev series uniform approximation theory includes: The integral term characterizing the contribution of the frequency-domain scattered sound field Separate into rapidly changing terms Mild variable , , , , In the formula, The distance from the sound source to the reference point. The distance from the reference point to the receiver. It is the wave number. The imaginary unit, , These are weighting coefficients related to the geometry of the surface element. Let these be the coordinates of the vertex of the surface element in the local coordinate system. The wavenumber components are related to the incident and scattering directions. The slope parameter is related to the vertex coordinates. ; For the slowly varying term The Chebyshev polynomial approximation calculation is applied.

[0012] In one embodiment, the gradual change term is... The calculations using Chebyshev polynomial approximation include: The broadband frequency range to be calculated Transform to wavenumber domain ,in , The speed of sound in water, For frequency; Through coordinate transformation Wavenumber calculation area Mapped to ; use Chebyshev polynomial of the first kind For functions Approximation is performed within the aforementioned wideband frequency range: , In the formula, the approximation coefficient , The wave value at the corresponding Chebyshev node is obtained by calculating... Chebyshev polynomial of the first kind exist On Zero points ; through inverse transformation The Chebyshev nodes in the wavenumber domain are obtained. .

[0013] In one embodiment, the method further includes: Based on the frequency-domain scattered sound field or the broadband time-domain scattered waveform, the scattering transmission characteristic curve of the complex target under dynamic measurement conditions is calculated. The transmission characteristic curve reflects the relationship between the target echo intensity and the horizontal distance between the sound source and the target.

[0014] In one embodiment, the size of each triangular element in the triangular element mesh satisfies the non-near-field calculation condition: the distance between the sound source or receiver and a single triangular element. The feature dimensions of this element incident sound wave wavelength satisfy This is to ensure the applicability of the physical acoustic module method.

[0015] This invention also provides a device for rapid prediction of the acoustic scattering characteristics of complex targets under finite beam incidence, comprising: The triangular surface mesh module is used to construct a three-dimensional geometric model of a complex target and divide the surface of the three-dimensional geometric model into a triangular surface mesh. The maximum size of the triangular surface mesh is set according to the wavelength of the incident sound wave. The triangular element filtering module is used to calculate the angle between the direction vector of the triangular element to the sound source and the beam direction vector for each triangular element in the triangular element grid, based on the incident parameters including the sound source position, beam direction vector and beam angle of the set finite beam, and to filter the triangular element as an element illuminated by the finite beam if the angle is less than half of the beam angle. The frequency domain scattering sound field acquisition module is used to calculate the scattering contribution of all selected illuminated surface elements in the frequency domain using the physical acoustic block element method, and to coherently superimpose the scattering contributions of all illuminated surface elements to obtain the frequency domain scattering sound field of the complex target under the finite beam incident. The broadband time-domain scattering waveform calculation module is used to interpolate and approximate the frequency-domain scattering sound field in a broadband frequency range using the Chebyshev series uniform approximation theory to obtain the broadband scattering response, and to calculate the broadband time-domain scattering waveform of the complex target under finite beam incident by inverse Fourier transform.

[0016] The aforementioned method and apparatus for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence firstly constructs a triangular mesh of the target surface and geometrically selects each mesh based on the sound source location, beam direction, and beam angle parameters. This precisely defines the target surface area actually illuminated by the finite beam, overcoming the limitations of the far-field plane wave assumption in traditional acoustic scattering modeling and extending its applicability to near-field finite beam incidence conditions. Next, based on the physical acoustic plate principle, the scattering contribution is calculated and coherently superimposed only on the selected illuminated meshes, achieving accurate and efficient prediction of the target's frequency-domain scattered sound field under finite beam spatial energy distribution constraints. Furthermore, to address the demands of broadband computing, the Chebyshev series uniform approximation theory is employed to interpolate and approximate the frequency domain scattering response, avoiding the enormous computational overhead associated with traditional frequency-by-frequency calculations. Finally, the time-domain scattering waveform is rapidly obtained through inverse Fourier transform, thereby significantly improving the prediction efficiency of broadband acoustic scattering characteristics of complex targets under finite beam incidence, particularly the time-domain dynamic characteristics, while ensuring accuracy. This meets the real-time computational requirements of practical engineering applications such as near-field detection and dynamic characteristic analysis. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating a method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence, as shown in one embodiment. Figure 2 A three-dimensional geometric model diagram of a typical complex target; Figure 3 This is a typical complex target triangular surface mesh model diagram; Figure 4 This is a schematic diagram of the target surface mesh generation and processing. Figure 5 A schematic diagram for calculating acoustic scattering of complex targets under finite beam incidence; Figure 6 This is a technical roadmap for a method of rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence, as shown in one embodiment. Figure 7 A schematic diagram for determining the integration region; Figure 8 A schematic diagram of the illumination area when incident at different beam angles; Figure 9 The graph shows the variation of echo intensity of a benchmark target with incident sound frequency when a finite beam is incident transversely. Figure 10 This is a comparison chart of computational efficiency after applying the acceleration algorithm; Figure 11 Time-domain waveforms of scattering from different parts of the target under broadband finite beam incident conditions; Figure 12 A schematic diagram illustrating the benchmark pass characteristics calculation under finite beam incidence. Figure 13 The transmission characteristics curves of the Benchmark target under finite beam incidence at different depth differences are shown. Figure 14 A schematic diagram of a rapid prediction device for acoustic scattering characteristics of complex targets under finite beam incidence, as shown in one embodiment. Figure 15 This is an internal structural diagram of an electronic device according to one embodiment. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The following is combined with Figures 1-15 This invention describes a method and apparatus for rapid prediction of the acoustic scattering characteristics of complex targets under finite beam incidence.

[0021] like Figure 1 As shown in one embodiment, a method for rapid prediction of the acoustic scattering characteristics of complex targets under finite beam incidence includes the following steps: Step S110: Construct a three-dimensional geometric model of the complex target and divide the surface of the three-dimensional geometric model into a triangular mesh. The maximum size of the triangular mesh is set according to the wavelength of the incident sound wave.

[0022] Specifically, CAD geometric modeling software is used to construct a three-dimensional geometric model of a typical complex underwater target for reference. Figure 2 The 3D geometric model was imported into mesh generation software. The target surface was selected as the target area for mesh generation, and the mesh type was specified as triangular mesh. The maximum mesh size was set to one-quarter of the incident sound wave wavelength, meaning the target surface was divided into triangular elements according to the requirement that the maximum size should not exceed one-quarter of the incident sound wave wavelength. Mesh generation was then performed to obtain a mesh element model of the complex target. Figure 3 Export the node coordinates of the mesh elements. The topology results for each facet node (each facet contains three node numbers) are shown in the reference. Figure 4 The target surface mesh generation and processing provides a discretized geometric basis for subsequent finite beam illumination region determination and scattering calculations, ensuring the computational accuracy of the physical acoustic plate element method. (Refer to...) Figure 5 A schematic diagram illustrating the acoustic scattering calculation of a complex target under finite beam incidence is provided. The diagram shows the relative positional relationship between the sound source and the benchmark target, including different incidence azimuths such as 90° transverse incidence, 180° bow incidence, and 0° stern incidence, as well as geometric parameters such as the beam angle θ and depth difference H of the finite beam. Simultaneously, reference is made to... Figure 6 The technical approach includes, in sequence, a preprocessing stage (using CAD modeling software to establish a complex target geometric model and dividing the complex target surface into triangular surface element meshes), a parameter setting and surface element selection stage (setting the incident beam parameters and selecting surface elements of the target illuminated by a finite beam), a scattering calculation stage (using a physical acoustic plate element fast calculation method combined with Chebyshev series broadband acoustic scattering waveform fast calculation), and a result display stage (outputting the acoustic scattering intensity and time-domain waveform of the complex target under underwater finite sound beam incident, as well as the transmission characteristic curve of the acoustic scattering of the moving target).

[0023] Step S120: Based on the incident parameters of the set finite beam, including the sound source position, beam direction vector and beam angle, for each triangular element in the triangular element grid, calculate the angle between the direction vector of the triangular element to the sound source and the beam direction vector, and in response to the angle being less than half of the beam angle, filter the triangular element as an element illuminated by the finite beam.

[0024] The specific screening process includes calculating the vector from the target surface element to the sound source. , The coordinates of the target surface source (usually the center or vertex coordinates of the surface element). Given the coordinates of the sound source; calculate the unit vector from the target surface element to the sound source. ,in ; Obtain the unit vector of the transmitted beam's acoustic axis direction Calculate the included angle cosine value Determine if the condition is met. ,in The beam angle is half of the stated beam angle; if this condition is met, the triangular element is determined to be within the finite beam and illuminated. (Refer to...) Figure 7 The diagram shows the integral region for determining the main sound axis. The vector from the sound source to the surface element The angle between the surface element and the main sound axis and beam half-angle The geometric relationship, by judging Right now Determine whether the surface element is located within the illuminated area of ​​the finite beam. (Refer to...) Figure 8 Irradiation area at different beam angles (including plane wave, , , , , (Beam angle) As the beam angle decreases, the illuminated area gradually shrinks from the entire target surface to a localized area. Specifically... Figure 8 (a) Shows that the entire surface of the model is illuminated when illuminated by a plane wave. Figure 8 (b) to Figure 8 (f) Shows how the illuminated area gradually shrinks from a large area on the side of the target to a small, localized bright spot as the beam angle decreases from 80° to 10°, where 8(b) is the 80° beam angle illumination area, 8(c) is the 60° beam angle illumination area, 8(d) is the 45° beam angle illumination area, 8(e) is the 30° beam angle illumination area, and 8(f) is the 10° beam angle illumination area. Furthermore, when the beam angle is 10°, only a very small area of ​​the target surface is illuminated. In specific implementation, the incident sound wave frequency is set to 50kHz, the distance between the finite beam sound source and the target center is 40m, and the incident azimuth angle is 90°. The wave types are plane wave, beam angle 80°, beam angle 60°, beam angle 45°, beam angle 30°, and beam angle 10°. The cosine of the angle between the center of the surface element and the direction of the sound source's emission axis is calculated using the above formula. Then, the surface elements illuminated by the beam are selected using a judgment condition. This surface element selection mechanism transforms the calculation of target acoustic scattering under finite beam incidence into a surface scattering integral problem on the target surface of the region illuminated by the finite beam, avoiding complex finite beam sound source modeling. Only the two-dimensional beam angle and the distance parameters between the sound source and the target need to be considered. It is applicable to arbitrary beam conditions such as circular beams, square beams, conical beams, and Gaussian beams. The dimensions of each triangular surface element in the triangular surface element mesh satisfy the non-near-field calculation condition: the distance between the sound source or receiver and a single triangular surface element... The feature dimensions of this element incident sound wave wavelength satisfy To ensure the applicability of the physical acoustic plate element method, this condition guarantees that the basic assumptions of the plate element method hold, making the calculation model applicable to the calculation of acoustic scattering characteristics in both the near-field region (Fresnel region) and the far-field region (Fraunhofer region).

[0025] Step S130: Using the physical acoustic block element method, calculate the scattering contribution of all selected illuminated surface elements in the frequency domain, and coherently superimpose the scattering contributions of all illuminated surface elements to obtain the frequency domain scattering sound field of the complex target under finite beam incidence.

[0026] Based on the high-frequency assumption, the boundary conditions on the illuminated surface element will be satisfied. and The sound field was calculated using Rayleigh Kirchhoff's integral formula, where the scattering contribution of each surface element was determined. Let be the incident wave potential function. Let be the potential function of the scattered wave. For the surface element normal direction. The expression is Surface acoustic impedance Under the assumption of rigid boundaries, the sound field tends to infinity. The expression for the sound field can be derived from the boundary conditions of the target surface: In this formula That is, the potential function of the scattered wave; for the case of combined transmission and reception. , The formula can be simplified to: In principle, this formula applies to any propagation distance range, including both near and far fields. The intensity of the sonar target under far-field conditions is obtained: ,in Specifically, for a combined transceiver sound source and receiver, the frequency domain scattering contribution of each illuminated surface element is based on the integral. calculate, The expression form is: In the formula, It is a vector from any point on the surface element to a preset reference point. It is the unit normal vector of this surface element. It is the unit vector from the reference point to the far-field receiving point. It is the wave number. This represents the illuminated triangular facet region. Specifically, the plate-based method integrates... Represented as For a single triangular plate element, its integral ,in , , , It is the number of vertices of the polygon (for triangles) ), These are the coordinates of the polygon's vertices. and The expression is , To calculate the echo intensity of a complex target, first divide the target surface into a series of triangular sections, and then use CAD software to section the target surface. Each grid is used to obtain the element of each segment. Topological information: surface index and node coordinates, which can be expressed as the sum of plate contributions using an integral formula: ,in It is during the combined sending and receiving process. The angle between the normal of each plate element and the incident and reflection directions is such that, since the normals of each plate element are different, they need to be mapped to a unified reference plane before integration, resulting in: ,in , It is the first after unified mapping The node coordinates of each segment It is the first The angle between the normal to the plate and the incident sound ray.

[0027] Based on points Calculate the echo intensity of complex targets under finite beam incidence. and far-field target intensity The calculation formulas are as follows: and In the formula, The distance between the sound source or receiver and the reference point. For wave number, The distance from the sound source to the reference point. The distance from the reference point to the receiver. The unit is imaginary. For near-field conditions, echo intensity... Characterizing the relationship between the intensity of target scattering and the distance from the target to the sound pressure level; for the far field, the target intensity... Independent of distance, this physical acoustic block-based method efficiently determines the incident region of a finite beam by discretizing the complex target surface into triangular elements and combining them with an element selection strategy. It achieves efficient solution for the scattered sound field of arbitrary beam angles and target structures, offering advantages such as clear physical concepts and high computational accuracy. In practical implementation, the scattered sound field under finite acoustic beam incidence is calculated using a benchmark model. The calculation uses a 1:10 scaled-down benchmark model with rigid boundary conditions. Based on the emission and target distances, the action region is divided into the Fraunhofer region, the Fresnel region, and the near-field region. ( (For the target size), the incident frequency range is set to 20kHz-50kHz, and the incident sound amplitude is 1Pa. To ensure that the surface elements of the plate element meet the non-near-field conditions, the surface mesh is divided according to the maximum size. This corresponds to a wavelength of 50kHz, the highest calculation frequency. Far-field distance criterion for a single surface element The far-field criterion is satisfied at a horizontal distance of 40m. See [link / reference]. Figure 9The curves showing the variation of echo intensity of a benchmark target incident on a finite beam with incident sound frequency are presented. The solid line represents the significant fluctuation of echo intensity with frequency under omnidirectional sound source illumination. The dashed line (beam angle 4°) and the dotted line (beam angle 2°) show that as the beam angle decreases, the range of echo intensity fluctuation gradually decreases. When the beam angle is 2°, the amplitude of echo intensity variation with frequency does not exceed 4dB, which is relatively stable. This indicates that when the sound beam angle gradually narrows, the beam only illuminates a local area of ​​the target, the number of scattering paths is significantly reduced, the interference term weakens, and the main path (such as positive transverse specular reflection) dominates the scattering response, resulting in a decrease in the amplitude of echo intensity variation with frequency.

[0028] Step S140: Using the Chebyshev series uniform approximation theory, the frequency domain scattered sound field is interpolated and approximated in the broadband frequency range to obtain the broadband scattering response, and the broadband time domain scattering waveform of the complex target under finite beam incident is calculated by inverse Fourier transform.

[0029] The integral term characterizing the contribution of the frequency-domain scattered sound field Separate into rapidly changing terms Mild variable , , , In the formula, The distance from the sound source to the reference point. The distance from the reference point to the receiver. The imaginary unit, , These are the weighting coefficients related to the geometry of the surface element, corresponding to the weighting coefficients for the incident and scattering directions, respectively. , and mapping factor Related, specifically manifested as ,and , In , Let be the direction cosine components of the incident and scattered directions in the local coordinate system. Let these be the coordinates of the vertex of the surface element in the local coordinate system. The wavenumber components are related to the incident and scattering directions. The slope parameter is related to the vertex coordinates and For slowly changing terms The Chebyshev polynomial approximation calculation is applied.

[0030] Specifically, let for The recurrence relation for a Chebyshev polynomial of the first kind of order is defined as follows: , , ; , For a given function domain objective function First, perform a coordinate transformation, let: Then the objective function can be expressed as: Then the Chebyshev approximation of the objective function in its domain is: ;like for of Then, by the properties of Chebyshev polynomials, we have: , ; ;in for The Chebyshev nodes in the equation can be obtained by inverse calculation using the following formula: , Specifically, this includes calculating the broadband frequency range. Transform to wavenumber domain ,in , The speed of sound in water, For frequency, through coordinate transformation Wavenumber calculation area Mapped to ,use Chebyshev polynomial of the first kind For functions Approximation is performed over a wide frequency range: The approximation coefficient , The wave value at the corresponding Chebyshev node is obtained by calculation. Chebyshev polynomial of the first kind exist On Zero points Through inverse transformation Obtain Chebyshev nodes in the wavenumber domain This Chebyshev approximation uses the roots of the first-kind Chebyshev polynomial to interpolate the objective function. The corresponding interpolation polynomial minimizes the Runge phenomenon and provides the best uniform approximation for continuous functions, requiring only a finite number of zeros. Integral terms The values ​​at other frequency points are obtained through approximation, which increases the calculation speed of target echoes under broadband signal incidence by nearly two orders of magnitude (see reference). Figure 10 The figure compares the computational efficiency after adopting the accelerated algorithm, showing that the computation time before acceleration varies with the number of discrete surface elements. Present Growth, and then acceleration The computational speed has increased by nearly two orders of magnitude, solving the problem of low efficiency in frequency-point-by-frequency calculations and enabling rapid prediction of broadband time-domain scattering waveforms. Specifically, the time-domain scattering waves are calculated when a broadband finite beam is incident from different parts of the target. The beam angle is 50°, and the incident directions are sequentially from the head, middle, and tail of the target. The incident sound wave frequency is a 20kHz-50kHz frequency-modulated signal with a pulse width of 0.5ms. First, a frequency domain transformation is performed based on the transmitted time-domain signal. Then, the time delay is calculated based on the distance between the transmitter and the target. The frequency-domain scattering intensity of the Benchmark model calculated by the finite beam physical acoustic module method is interpolated using Chebyshev uniform approximation to obtain the broadband acoustic scattering transfer function. Then, the transmitted signal and the superimposed frequency-domain transfer function are multiplied, and an inverse Fourier transform is performed, referring to... Figure 11 The time-domain scattering waveforms of different parts (head, middle, and tail) of a target under broadband finite beam incident light, among which... Figure 11 (a) Displays the echo signal when incident from the target's head. Figure 11 (b) Displays the echo signal when incident from the center of the target. Figure 11 (c) The echo signal is shown when it is incident from the tail of the target. The three have significant differences in waveform structure, peak amplitude and arrival time. This is mainly due to the different illuminated area of ​​the surface element under the finite beam incident, and the significant difference in the total scattered sound field after the coherent superposition of the scattered sound fields of each surface element.

[0031] Based on the frequency domain scattered sound field or broadband time domain scattered waveform, the scattering transmission characteristic curve of complex targets under dynamic measurement conditions is calculated. This characteristic curve reflects the relationship between the target echo intensity and the horizontal distance between the sound source and the target. In specific implementation, the sound source is considered to be located below the target, with the sound beam incident vertically upwards, and the sound source passing directly below the target at a certain speed. Specifically, considering the sound source is located below the target, the sound beam incident vertically upwards, and the sound source passing directly below the target at a certain speed, the depth differences between the sound source and the target are calculated to be 10m and 40m, respectively, with the sound beam's starting and ending points 20m from the bottom of the target. During the cross-beam intersection process, the benchmark target echo intensity transmission characteristic curve is calculated at different beam angles. The horizontal axis represents the horizontal distance between the sound source and the target, with 0m indicating the source is directly below the target. The vertical axis represents the echo intensity value. (Refer to...) Figure 12 A schematic diagram of the benchmark characteristic calculation under finite beam incidence, calculating the depth difference between the emitted sound source and the target at different depths (e.g., , The variation law of the target echo intensity at time ) is obtained as follows Figure 13 The transmission characteristic curves of the Benchmark target under finite beam incidence at different depth differences are shown below. Figure 13(a) Displays the transmission characteristic curves of an omnidirectional sound source with beam angles of 8°, 4°, and 2° when the depth difference is 10m. Figure 13 (b) The corresponding curve is shown when the depth difference is 40m. It can be seen that as the depth difference increases, the illumination range at the same beam angle expands, the width of the characteristic curve increases, and the smaller the beam angle, the narrower the main lobe of the curve and the more obvious the side lobe suppression effect. The horizontal axis is the horizontal distance between the sound source and the target. (Indicates that it is located directly below the target), and the vertical axis represents the echo intensity value. This characteristic curve can be used to analyze the variation of the near-field echo intensity of the target with the incident beam opening angle and the distance between the sound source and the target. It provides theoretical support for predicting the acoustic scattering characteristics of complex targets under finite beam incidence, accurately identifying target parts with different curvatures, and evaluating the detection accuracy and strike effect of underwater combat systems.

[0032] The following describes the rapid prediction device for the acoustic scattering characteristics of complex targets under finite beam incidence provided by the present invention. The rapid prediction device for the acoustic scattering characteristics of complex targets under finite beam incidence described below can be referred to in correspondence with the rapid prediction method for the acoustic scattering characteristics of complex targets under finite beam incidence described above.

[0033] like Figure 14 As shown, in one embodiment, a device for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incident includes a triangular surface segmentation module 1410, a triangular surface screening module 1420, a frequency domain scattering sound field acquisition module 1430, and a broadband time domain scattering waveform calculation module 1440.

[0034] The triangular surface meshing module 1410 is used to construct a three-dimensional geometric model of a complex target and to mesh the surface of the three-dimensional geometric model into triangular surface meshes. The maximum size of the triangular surface meshes is set according to the wavelength of the incident sound wave.

[0035] The triangular element filtering module 1420 is used to calculate the angle between the direction vector from the triangular element to the sound source and the beam direction vector for each triangular element in the triangular element grid, based on the incident parameters including the sound source location, beam direction vector and beam angle of the set finite beam, and to filter the triangular element as an element illuminated by the finite beam if the angle is less than half of the beam angle.

[0036] The frequency domain scattering sound field acquisition module 1430 is used to calculate the scattering contribution of all selected illuminated surface elements in the frequency domain using the physical acoustic block element method, and coherently superimpose the scattering contributions of all illuminated surface elements to obtain the frequency domain scattering sound field of the complex target under finite beam incidence.

[0037] The broadband time-domain scattering waveform calculation module 1440 is used to interpolate and approximate the frequency-domain scattering sound field in the broadband frequency range using the Chebyshev series uniform approximation theory, obtain the broadband scattering response, and calculate the broadband time-domain scattering waveform of complex targets under finite beam incident by inverse Fourier transform.

[0038] Figure 15 This example illustrates a schematic diagram of the physical structure of an electronic device, which can be a smart terminal. Its internal structure diagram can be as follows: Figure 15 As shown. The electronic device includes a processor, memory, and a network interface connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The network interface is used to communicate with external terminals via a network connection. When the computer program is executed by the processor, it implements a method for rapid prediction of the acoustic scattering characteristics of complex targets under finite beam incidence, the method including: A three-dimensional geometric model of a complex target is constructed, and the surface of the three-dimensional geometric model is divided into a triangular mesh, the maximum size of which is set according to the wavelength of the incident sound wave.

[0039] Based on the incident parameters of the finite beam, including the sound source location, beam direction vector, and beam angle, for each triangular element in the triangular element mesh, the angle between the direction vector from the triangular element to the sound source and the beam direction vector is calculated. In response to the angle being less than half of the beam angle, the triangular element is selected as an element to be illuminated by the finite beam.

[0040] The physical acoustic block element method is used to calculate the scattering contribution of all selected illuminated surface elements in the frequency domain, and the scattering contributions of all illuminated surface elements are coherently superimposed to obtain the frequency domain scattering sound field of complex targets under finite beam incidence.

[0041] Using the Chebyshev series uniform approximation theory, the frequency-domain scattered sound field is interpolated and approximated in the broadband frequency range to obtain the broadband scattering response. The broadband time-domain scattering waveform of complex targets under finite beam incident is calculated by inverse Fourier transform.

[0042] Those skilled in the art will understand that Figure 15 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the electronic device to which the present invention is applied. A specific electronic device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0043] On the other hand, the present invention also provides a computer storage medium storing a computer program, which, when executed by a processor, implements a method for rapid prediction of the acoustic scattering characteristics of complex targets under finite beam incidence. This method includes: A three-dimensional geometric model of a complex target is constructed, and the surface of the three-dimensional geometric model is divided into a triangular mesh, the maximum size of which is set according to the wavelength of the incident sound wave.

[0044] Based on the incident parameters of the finite beam, including the sound source location, beam direction vector, and beam angle, for each triangular element in the triangular element mesh, the angle between the direction vector from the triangular element to the sound source and the beam direction vector is calculated. In response to the angle being less than half of the beam angle, the triangular element is selected as an element to be illuminated by the finite beam.

[0045] The physical acoustic block element method is used to calculate the scattering contribution of all selected illuminated surface elements in the frequency domain, and the scattering contributions of all illuminated surface elements are coherently superimposed to obtain the frequency domain scattering sound field of complex targets under finite beam incidence.

[0046] Using the Chebyshev series uniform approximation theory, the frequency-domain scattered sound field is interpolated and approximated in the broadband frequency range to obtain the broadband scattering response. The broadband time-domain scattering waveform of complex targets under finite beam incident is calculated by inverse Fourier transform.

[0047] In another aspect, a computer program product or computer program is provided, comprising computer instructions stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium, and when the processor executes the computer instructions, it implements a method for rapid prediction of the acoustic scattering characteristics of complex targets under finite beam incidence, the method comprising: A three-dimensional geometric model of a complex target is constructed, and the surface of the three-dimensional geometric model is divided into a triangular mesh, the maximum size of which is set according to the wavelength of the incident sound wave.

[0048] Based on the incident parameters of the finite beam, including the sound source location, beam direction vector, and beam angle, for each triangular element in the triangular element mesh, the angle between the direction vector from the triangular element to the sound source and the beam direction vector is calculated. In response to the angle being less than half of the beam angle, the triangular element is selected as an element to be illuminated by the finite beam.

[0049] The physical acoustic block element method is used to calculate the scattering contribution of all selected illuminated surface elements in the frequency domain, and the scattering contributions of all illuminated surface elements are coherently superimposed to obtain the frequency domain scattering sound field of complex targets under finite beam incidence.

[0050] Using Chebyshev series uniform approximation theory, the frequency-domain scattered sound field is interpolated and approximated over a wide frequency range to obtain a wideband scattering response. The wideband time-domain scattering waveform of a complex target under finite beam incident is then calculated using inverse Fourier transform. Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. This computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory.

[0051] By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0052] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0053] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence, characterized in that, The method includes: A three-dimensional geometric model of a complex target is constructed, and the surface of the three-dimensional geometric model is divided into a triangular mesh, the maximum size of which is set according to the wavelength of the incident sound wave. Based on the incident parameters of the finite beam, including the sound source location, beam direction vector, and beam angle, for each triangular element in the triangular element grid, the angle between the direction vector of the triangular element to the sound source and the beam direction vector is calculated, and in response to the angle being less than half of the beam angle, the triangular element is selected as an element illuminated by the finite beam. Using the physical acoustic block element method, the scattering contribution of all selected illuminated surface elements in the frequency domain is calculated, and the scattering contributions of all illuminated surface elements are coherently superimposed to obtain the frequency domain scattering sound field of the complex target under the incident finite beam. Using the Chebyshev series uniform approximation theory, the frequency-domain scattered sound field is interpolated and approximated over a wide frequency range to obtain a wide-bandgap scattering response. The wide-bandgap time-domain scattering waveform of the complex target under finite beam incident is then calculated using inverse Fourier transform.

2. The method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence according to claim 1, characterized in that, The process of dividing the surface of the three-dimensional geometric model into a triangular mesh is as follows: The target surface is divided into triangular elements according to the requirement that the maximum size does not exceed one-quarter of the incident sound wave wavelength.

3. The method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence according to claim 1 or 2, characterized in that, The step of calculating the angle between the direction vector of the triangular surface element to the sound source and the beam direction vector, and in response to the angle being less than half of the beam angle, filtering the triangular surface element as a surface element illuminated by the finite beam, includes: Calculate the vector from the target surface element to the sound source. , The coordinates of the target surface source, The coordinates of the sound source; Calculate the unit vector from the target surface element to the sound source. ,in ; Obtain the unit vector of the transmitted beam acoustic axis direction ; Calculate the included angle cosine value ; Determine if it satisfies ,in The beam angle is half of the beam angle, i.e., the beam half angle. If this condition is met, the triangular element is determined to be located within the finite beam and illuminated.

4. The method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence according to claim 1 or 2, characterized in that, The method employing physical acoustics block element theory calculates the scattering contribution of all selected illuminated surface elements in the frequency domain, specifically as follows: Based on the high-frequency assumption, the boundary conditions on the illuminated surface element are satisfied. and The sound field was calculated using Rayleigh Kirchhoff's integral formula, where the scattering contribution of each surface element was determined. Let be the incident wave potential function. Let be the potential function of the scattered wave. For the surface element normal direction.

5. The method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence according to claim 4, characterized in that, For a combined transceiver sound source and receiver, the frequency domain scattering contribution of each illuminated surface element is based on an integral. Calculation, where The expression form is: ， In the formula, It is a vector from any point on the surface element to a preset reference point. It is the unit normal vector of this surface element. It is the unit vector from the reference point to the far-field receiving point. It is the wave number. This represents the illuminated triangular facet region.

6. The method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence according to claim 5, characterized in that, Based on the integral Calculate the echo intensity of the complex target under the finite beam incident light. and far-field target intensity The calculation formula is: ， ， In the formula, The distance between the sound source or receiver and the reference point. For wave number, The distance from the sound source to the reference point. The distance from the reference point to the receiver. It is the imaginary unit.

7. The method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence according to claim 1, characterized in that, The method of using Chebyshev series uniform approximation theory to interpolate and approximate the frequency-domain scattered sound field over a wide frequency range includes: The integral term characterizing the contribution of the frequency-domain scattered sound field Separate into rapidly changing terms Mild variable , , ， ， In the formula, The distance from the sound source to the reference point. The distance from the reference point to the receiver. It is the wave number. The imaginary unit, , These are weighting coefficients related to the geometry of the surface element. Let these be the coordinates of the vertex of the surface element in the local coordinate system. The wavenumber components are related to the incident and scattering directions. The slope parameter is related to the vertex coordinates. ; For the slowly varying term The Chebyshev polynomial approximation calculation is applied.

8. The method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence according to claim 7, characterized in that, The slowly varying term The calculations using Chebyshev polynomial approximation include: The broadband frequency range to be calculated Transform to wavenumber domain ,in , The speed of sound in water, For frequency; Through coordinate transformation Wavenumber calculation area Mapped to ; use Chebyshev polynomial of the first kind For functions Approximation is performed within the aforementioned wideband frequency range: ， In the formula, the approximation coefficient , For the corresponding cut ratio The wave value at the Shev node is obtained by calculating... Chebyshev polynomial of the first kind exist On Zero points ; through inverse transformation The Chebyshev nodes in the wavenumber domain are obtained. .

9. The method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence according to claim 1, characterized in that, The method further includes: Based on the frequency-domain scattered sound field or the broadband time-domain scattered waveform, the scattering transmission characteristic curve of the complex target under dynamic measurement conditions is calculated. The transmission characteristic curve reflects the relationship between the target echo intensity and the horizontal distance between the sound source and the target.

10. The method for rapid prediction of acoustic scattering characteristics of complex targets under finite beam incidence according to claim 1, characterized in that, The dimensions of each triangular element in the triangular mesh satisfy the non-near-field calculation condition: the distance between the sound source or receiver and a single triangular element. The feature dimensions of this element incident sound wave wavelength satisfy This is to ensure the applicability of the physical acoustic module method.

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