A method, device and medium for calculating the position of deep-sea convergence zone based on acoustic diffraction phase shift

Abstract

The present invention proposes a method, device and medium for calculating the position of a deep-sea convergence zone based on acoustic diffraction phase shift. Based on MRT, the present invention uses a numerical method to introduce an additional functional phase shift at the sound line inversion point, and uses the functional phase shift to obtain the additional horizontal displacement of the sound line at the inversion point, so that the sound line in the deep-sea waveguide and the simple normal wave can establish an accurate equivalent relationship under low-frequency conditions through the WKB method. Here, the reflection phase shift caused when the inversion point in MRT is close to the waveguide interface and the functional phase shift introduced at the inversion point are collectively referred to as acoustic diffraction phase shift. Research has found that only by considering these two types of acoustic diffraction phase shifts at the same time can the span, propagation delay and group velocity of the sound line in the deep-sea waveguide be accurately corrected. On this basis, the present invention proposes a method suitable for calculating the position of a deep-sea convergence zone under low-frequency conditions. Finally, by studying the position of different types of convergence zones in a complete deep-sea sound channel at low frequencies, the formation mechanism of the convergence zone at low frequencies is revealed.

Description

Technical Field

[0001] The present invention belongs to the technical field of position calculation of deep-sea convergence zones, and in particular relates to a method, device and medium for calculating the position of deep-sea convergence zones based on acoustic diffraction phase shift. Background Art

[0002] The sound wave is generated by the sound line reversal point Phase shift is an ideal approximation at high frequencies. At low frequencies, a functional phase shift should also be considered at the ray reversal point. A reflection phase shift also occurs when the ray reversal point is close to the waveguide interface. These two phase shifts occur alongside the phenomenon of acoustic diffraction, and the phase shift becomes more pronounced at lower frequencies. This is referred to in this paper as acoustic diffraction phase shift. To accurately calculate the position of the deep-sea convergence zone at low frequencies, the acoustic diffraction phase shift is used to correct the errors in classical ray theory when calculating ray span, propagation delay, and group velocity. The validity of the correction results is verified using simple normal wave theory. Based on this, a method for calculating the position of the deep-sea convergence zone under low-frequency conditions is proposed. This method takes into account the influence of acoustic diffraction phase shift, has clear physical meaning, and is simple and accurate in calculation. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems in the prior art and to propose a method, device and medium for calculating the position of a deep-sea convergence zone based on acoustic diffraction phase shift.

[0004] The present invention is achieved through the following technical solutions: a method for calculating the position of a deep-sea convergence zone based on acoustic diffraction phase shift is proposed. Based on MRT, a numerical method is used to introduce an additional functional phase shift at the sound ray inversion point. The functional phase shift is used to obtain the additional horizontal displacement of the sound ray at the inversion point, thereby establishing an accurate equivalent relationship between the sound ray and the simple normal wave in the deep-sea waveguide under low-frequency conditions using the WKB method.

[0005] Let c0 be the speed of sound at the sound source, and θ0 be the grazing angle of the sound ray:

[0006]

[0007] The horizontal distance from the upper inversion point to the sound source and receiver, as well as the sound line span, are:

[0008]

[0009]

[0010]

[0011] Where a and b are the depths of the upper and lower inversion points respectively;

[0012] In a complete deep-sea sound channel, the convergence zone is divided into RR-type convergence zone and RSR-type convergence zone according to the different types of sound rays; according to the position of the convergence zone relative to the sound channel axis, it is divided into upper convergence zone and lower convergence zone; according to the formation mechanism of the convergence zone, it is divided into caustic convergence zone and inversion point convergence zone; according to the horizontal distance from the upper inversion point to the sound source and receiver, as well as the sound ray span, four types of RR-type refracted sound rays are summarized:

[0013] r1=jL+L0-L z (11a)

[0014] r2=jL-L0+L z (11b)

[0015] r3=jL-L0-L z (11c)

[0016] r4=jL+L0+L z (11d)

[0017] Where j represents the number of spans that the sound line travels;

[0018] If the above four types of sound rays satisfy the following conditions at distance r*:

[0019]

[0020] Then the sound rays intersect, and the sound energy is focused here to form a caustic point. Adjacent caustic points in the two-dimensional plane are connected to form caustic lines.

[0021] According to the characteristics of the four types of sound rays, the contribution of the non-uniform plane wave outside the upper and lower inversion points to the propagation distance, the contribution of the sea surface and seabed reflection phase shift to the propagation distance, and the propagation distance error within a span calculated using the diffraction phase shift are used to correct equations (11a), (11b), (11c), and (11d) to obtain:

[0022] r1 m =j(L-Δr)+L0-L z (13a)

[0023]

[0024]

[0025]

[0026] It can be seen from equations (13a), (13b), (13c) and (13d) that the introduction of the acoustic diffraction phase shift will re-change the positions of the acoustic ray inversion point and the caustics in the classical ray theory, thereby affecting the positions of the inversion point convergence area and the caustics convergence area. When the frequency gradually increases so that the acoustic diffraction phase shift can be ignored, equations (13a), (13b), (13c) and (13d) degenerate into equations (11a), (11b), (11c) and (11d).

[0027] Furthermore, the sound velocity distribution is given by the Munk model, which has the following general form:

[0028] c(z)=C1[1+ε(η+e -η -1)] (1)

[0029] Where C1 is the sound velocity of the sound channel axis, ε=Bγ A / 2=7.41×10 -3 , B = 1300m is the scale depth, γ A =1.14×10 -5 m -1 is the sound velocity gradient in an adiabatic environment, η = 2(z-z1) / B is a dimensionless distance parameter, and z1 is the axial depth of the sound channel.

[0030] Furthermore, the reflection phase shift caused when the inversion point in MRT is close to the waveguide interface and the functional phase shift introduced at the inversion point are collectively referred to as the acoustic diffraction phase shift.

[0031] Furthermore, combined with the modal eigenfunction, additional functional phase shifts are introduced at the upper and lower inversion points of the sound line:

[0032]

[0033]

[0034] In formulas (2a) and (2b), a and b are the depths of the upper and lower inversion points, respectively. c'(a) and c'(b) are the derivatives of the sound velocity at the upper and lower inversion points, respectively. k r is the horizontal wave number, H is the sea depth, and δ is the Dirac function:

[0035]

[0036]

[0037] Furthermore, according to the MRT theory, the reflection phase shift caused by the sound ray reversal point approaching the absolute soft boundary can be written as:

[0038]

[0039] The reflection phase shift caused by the impedance boundary near the seabed can be written as:

[0040]

[0041] In equations (3a) and (3b), Ai and Bi represent the Airy function and Biry function, respectively, and τ is the Airy function and Biry function variable. When the inversion point is inside the waveguide:

[0042]

[0043]

[0044] When the inversion point exceeds the waveguide boundary, the sound velocity profile needs to be extended. In this case:

[0045]

[0046]

[0047] A zero τ value indicates that the inversion point is exactly at the waveguide boundary. A larger absolute value of τ indicates that the inversion point is farther from the waveguide boundary. The value of κ is related to the relative position of the inversion point and the waveguide interface:

[0048]

[0049]

[0050] Furthermore, the contributions of the non-uniform plane waves to the propagation distance outside the upper and lower inversion points are defined as:

[0051]

[0052]

[0053] Furthermore, the contributions of the sea surface and seabed reflection phase shift to the propagation distance are:

[0054]

[0055]

[0056] Furthermore, the propagation distance error within a span is calculated using the diffraction phase shift:

[0057] Δr=r pr +r bot -r a -r b (8).

[0058] The present invention proposes an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method for calculating the position of a deep-sea convergence zone based on acoustic diffraction phase shift are implemented.

[0059] The present invention proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of a method for calculating the position of a deep-sea convergence zone based on acoustic diffraction phase shift.

[0060] The beneficial effects of the present invention are:

[0061] 1) By comparing the calculation results with those of the simple normal wave, the acoustic diffraction phase shift can be used to accurately correct the errors of the classical ray theory in calculating the acoustic ray span, propagation delay and group velocity.

[0062] 2) A method suitable for calculating the caustic structure of deep-sea convergence zones under low-frequency conditions is proposed. This method takes into account the influence of diffraction phase shift, has clear physical meaning, and is simple and accurate to calculate. When the frequency gradually increases and the acoustic diffraction phase shift can be ignored, it degenerates into the method of classical ray theory. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a schematic diagram of the deep-sea sound channel model;

[0064] Figure 2 Schematic diagram of four types of refracted sound rays when the sound source depth is 500m and the receiving depth is 1000m; (a) r1; (b) r2; (c) r3; (d) r4;

[0065] Figure 3 The sound source depth is 500m; (a) caustics of the RR-type convergence zone at different frequencies; (b) propagation loss at 3kHz; (c) propagation loss at 100Hz; (d) propagation loss at 30Hz. DETAILED DESCRIPTION

[0066] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0067] The study of the first upper convergence zone in a complete deep-sea sound channel shows that under high-frequency conditions, the RR (Refracted-Refracted, RR) type convergence zone has three caustics, and the RSR (Refracted Surface-Reflected, RSR) type convergence zone has four caustics. By comparing with the high-frequency results, after considering the diffraction phase shift under low-frequency conditions, it was found that the horizontal sound line displacement caused by the interface reflection phase shift will cause the RR type caustics to shift horizontally toward the direction close to the sound source, and the RSR type sound line will produce several additional caustics, while the contribution of the non-uniform plane wave to the distance will cause both the RR type and RSR type caustics to shift horizontally away from the sound source. As the frequency increases, the sound diffraction effect decreases, and the caustic structure of the convergence zone tends to the calculation result of the classical ray theory. The present invention is applicable to both complete deep-sea sound channels and incomplete deep-sea sound channels.

[0068] At low frequencies, when sound waves pass through the sound line inversion point, they cannot be simply considered to be a constant phase shift. In order to accurately calculate the position of the convergence zone under low-frequency conditions, the present invention, based on MRT, uses a numerical method to introduce an additional functional phase shift at the sound line inversion point, and uses the functional phase shift to obtain the additional horizontal displacement of the sound line at the inversion point, so that the sound line in the deep-sea waveguide and the simple normal wave can establish an accurate equivalent relationship under low-frequency conditions through the WKB method. Here, the reflection phase shift caused when the inversion point in MRT is close to the waveguide interface and the functional phase shift introduced at the inversion point are collectively referred to as the acoustic diffraction phase shift. Studies have found that only by considering these two types of acoustic diffraction phase shifts at the same time can the span, propagation delay and group velocity of the sound line in the deep-sea waveguide be accurately corrected. On this basis, the present invention proposes a method suitable for calculating the position of the deep-sea convergence zone under low-frequency conditions. Finally, by studying the position of different types of convergence zones in a complete deep-sea sound channel at low frequencies, the formation mechanism of the convergence zone at low frequencies is revealed.

[0069] Combine Figure 1-Figure 3 The present invention proposes a method for calculating the position of deep-sea convergence zones based on acoustic diffraction phase shift. Based on MRT, a numerical method is used to introduce an additional functional phase shift at the sound ray inversion point. The functional phase shift is used to obtain the additional horizontal displacement of the sound ray at the inversion point, thereby establishing an accurate equivalent relationship between the sound ray and the simple normal wave in the deep-sea waveguide under low-frequency conditions using the WKB method.

[0070] Let c0 be the speed of sound at the sound source, and θ0 be the grazing angle of the sound ray:

[0071]

[0072] The horizontal distance from the upper inversion point to the sound source and receiver, as well as the sound line span, are:

[0073]

[0074]

[0075]

[0076] Where a and b are the depths of the upper and lower inversion points respectively;

[0077] exist Figure 1 In the complete deep-sea sound channel shown, the convergence zone is divided into RR-type and RSR-type convergence zones according to the type of sound rays. According to the position of the convergence zone relative to the sound channel axis, it is divided into upper and lower convergence zones. According to the formation mechanism of the convergence zone, it is divided into caustic convergence zone and inversion point convergence zone. In order to study the RR-type upper convergence zone formed by the sound source above the sound channel axis, four types of RR-type refracted sound rays are summarized based on the horizontal distance from the upper inversion point to the sound source and receiver, as well as the sound ray span:

[0078] r1=jL+L0-L z (11a)

[0079] r2=jL-L0+L z (11b)

[0080] r3=jL-L0-L z (11c)

[0081] r4=jL+L0+L z (11d)

[0082] Where j represents the number of spans that the sound line travels;

[0083] Figure 2 The red curve in the middle is a schematic diagram of four types of RR-type refracted sound rays when j = 1, with a source depth of 500m and a receiving depth of 1000m. The horizontal dotted line represents the receiving depth. It can be found that r1 and r2 both have one upper inversion point and one lower inversion point, r3 has only one lower inversion point, and r4 has two upper inversion points and one lower inversion point. This idea can be easily extended to RSR-type sound rays. When j = 1, for RSR-type sound rays, r1 and r2 both have one sea surface reflection and one lower inversion point, r3 has only one lower inversion point, and r4 has two sea surface reflections and one lower inversion point, as shown in the figure below. Figure 2 Indicated by the blue dotted line.

[0084] If the above four types of sound rays satisfy the following conditions at distance r*:

[0085]

[0086] Then the sound rays intersect, and the sound energy is focused here to form a caustic point. Adjacent caustic points in the two-dimensional plane are connected to form caustic lines.

[0087] Combine Figure 2The characteristics of the four types of sound lines in the equation (11a), (11b), (11c) and (11d) are corrected by using the contribution of the non-uniform plane wave outside the upper and lower inversion points to the propagation distance, the contribution of the sea surface and seabed reflection phase shift to the propagation distance, and the propagation distance error within a span calculated using the diffraction phase shift to obtain:

[0088] r1 m =j(L-Δr)+L0-L z (13a)

[0089]

[0090]

[0091]

[0092] From equations (13a), (13b), (13c) and (13d), we can see that r a With r b Increase the horizontal distance between the sound line and the sound source, r pr With r bot By reducing the horizontal distance between the sound line and the sound source, it can be foreseen that the introduction of the acoustic diffraction phase shift will re-change the positions of the sound line inversion point and the caustics in the classical ray theory, thereby affecting the positions of the inversion point convergence area and the caustics convergence area. When the frequency gradually increases so that the acoustic diffraction phase shift can be ignored, equations (13a), (13b), (13c) and (13d) degenerate into equations (11a), (11b), (11c) and (11d).

[0093] consider Figure 1 The horizontal layered environment model shown is independent of distance. The sea depth H = 5000m, the seabed is a semi-infinite liquid space, and the seabed sound speed c bot Take 1700m / s, longitudinal wave attenuation α bot =0.6dB / λ, λ is the wavelength of the sound wave, and the seabed density ρ bot =1.7g / cm 3 , the density of seawater is 1g / cm 3 , the sound velocity distribution is given by the Munk model, and its general form is as follows:

[0094] c(z)=C1[1+ε(η+e -η -1)] (1)

[0095] Where C1 is the sound velocity of the sound channel axis, ε=Bγ A / 2=7.41×10 -3 , B = 1300m is the scale depth, γ A =1.14×10 -5 m -1is the sound velocity gradient in an adiabatic environment, η = 2(z-z1) / B is a dimensionless distance parameter, and z1 is the axial depth of the vocal tract. Figure 1 z1=1200m,C1=1500m / s,conjugate depth z conj =4117m, the vertical distance from the conjugate depth to the seabed is the depth margin.

[0096] The reflection phase shift caused when the inversion point in MRT is close to the waveguide interface and the functional phase shift introduced at the inversion point are collectively referred to as acoustic diffraction phase shift.

[0097] Combined with the modal eigenfunction, additional functional phase shifts are introduced at the upper and lower inversion points of the sound line:

[0098]

[0099]

[0100] In formulas (2a) and (2b), a and b are the depths of the upper and lower inversion points, respectively. c'(a) and c'(b) are the derivatives of the sound velocity at the upper and lower inversion points, respectively. k r is the horizontal wave number, H is the sea depth, and δ is the Dirac function:

[0101]

[0102]

[0103] According to the MRT theory, the reflection phase shift caused by the sound ray reversal point approaching the absolute soft boundary (sea surface) can be written as:

[0104]

[0105] The reflection phase shift caused by the impedance boundary near the seabed can be written as:

[0106]

[0107] In equations (3a) and (3b), Ai and Bi represent the Airy function and Biry function, respectively, and τ is the Airy function and Biry function variable. When the inversion point is inside the waveguide:

[0108]

[0109]

[0110] When the inversion point exceeds the waveguide boundary, the sound velocity profile needs to be extended. In this case:

[0111]

[0112]

[0113] A zero τ value indicates that the inversion point is exactly at the waveguide boundary. A larger absolute value of τ indicates that the inversion point is farther from the waveguide boundary. The value of κ is related to the relative position of the inversion point and the waveguide interface:

[0114]

[0115]

[0116] Reusing the steady phase point condition, we define the contributions of the inhomogeneous plane wave to the propagation distance outside the upper and lower inversion points as follows:

[0117]

[0118]

[0119] The contributions of the sea surface and seabed reflection phase shift to the propagation distance are:

[0120]

[0121]

[0122] The propagation distance error within one span calculated using the diffraction phase shift is:

[0123] Δr=r pr +r bot -r a -r b (8).

[0124] Example

[0125] The present invention takes the first RR-type upper convergence zone as an example, and uses j as 1 in Formulas (11a), (11b), (11c) and (11d) and Formulas (13a), (13b), (13c) and (13d) to illustrate the use of the deep-sea convergence zone position calculation method based on acoustic diffraction phase shift to calculate the caustic structure of the convergence zone at low frequencies, and discusses the influence of acoustic diffraction phase shift on the caustic structure.

[0126] According to the method for calculating the position of the deep-sea convergence zone based on the acoustic diffraction phase shift described in the present invention, the caustic points are obtained from the entire depth from the sea surface to the sound channel axis (1200m) to obtain the caustic lines of the RR type convergence zone at different frequencies, such as Figure 3 As shown in (a). Figure 3 The black solid lines in (a) are RR-type caustics at high frequencies. The r1 type sound line forms a caustic line between the sea surface and the sound source depth (500 m), and the r2 type sound line forms a caustic line between the sound source depth and the sound channel axis. These two caustics intersect at the sound source depth to form a sharp focus. The r3 type sound line forms a caustic line between the sea surface and the sound channel axis. Figure 3 The red dotted and blue dashed lines in (a) are the RR-type caustics after considering the diffraction phase shift at 30 Hz and 100 Hz, respectively. Because the dispersion of the simple normal wave increases as the frequency decreases, the depth of the upper inversion point of the ray corresponding to the simple normal wave cannot continuously change from 0 m to 1200 m. Therefore, compared with the classical ray solution, the r1-type caustics and r3-type caustics are still some distance away from the sea surface at low frequencies, and the r1 and r2-type caustics cannot intersect at the sound source depth to form a sharp focus. Figure 3 (b) to Figure 3 (d) is a pseudo-color image of the propagation loss of the RR-type convergence zone at different frequencies. The sound field at 3 kHz is regarded as a high-frequency sound field, and the curve in the figure is the caustic line at the corresponding frequency. It can be seen that the caustic lines at different frequencies accurately appear in the orange-red highlighted area with low propagation loss in the pseudo-color image.

[0127] To accurately calculate the caustics in the convergence zone under low-frequency conditions, this paper combines the simple normal wave method with a detailed physical analysis of the causes of errors in classical ray theory. A ray method that incorporates acoustic diffraction phase shifts is proposed. The main conclusions of this paper are as follows:

[0128] 1) By comparing the calculation results with those of the simple normal wave, the acoustic diffraction phase shift can be used to accurately correct the errors of the classical ray theory in calculating the acoustic ray span, propagation delay and group velocity.

[0129] 2) A method suitable for calculating the caustic structure of deep-sea convergence zones under low-frequency conditions is proposed. This method takes into account the influence of diffraction phase shift, has clear physical meaning, and is simple and accurate to calculate. When the frequency gradually increases and the acoustic diffraction phase shift can be ignored, it degenerates into the method of classical ray theory.

[0130] The present invention proposes an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method for calculating the position of a deep-sea convergence zone based on acoustic diffraction phase shift are implemented.

[0131] The present invention proposes a computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the steps of a method for calculating the position of a deep-sea convergence zone based on acoustic diffraction phase shift.

[0132] The memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. The non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus RAM (DRRAM). It should be noted that the memory of the methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0133] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated therein. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a high-density digital video disc (DVD)), or a semiconductor medium (eg, a solid state disc (SSD)).

[0134] During implementation, each step of the above method can be completed by an integrated logic circuit of the hardware in the processor or by instructions in the form of software. The steps of the method disclosed in conjunction with the embodiments of the present application can be directly embodied as being executed by a hardware processor, or can be executed by a combination of hardware and software modules in the processor. The software module can be located in a storage medium mature in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in conjunction with its hardware. To avoid repetition, it will not be described in detail here.

[0135] It should be noted that the processor in the embodiments of the present application can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiment can be completed by an integrated logic circuit of the hardware in the processor or by instructions in the form of software. The above processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. The various methods, steps, and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor. The steps of the method disclosed in the embodiments of the present application can be directly embodied as being executed by a hardware decoding processor, or can be executed by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0136] The above is a detailed introduction to the method, equipment and medium for calculating the position of the deep-sea convergence zone based on acoustic diffraction phase shift proposed in the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technical personnel in this field, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for calculating the position of a deep-sea convergence zone based on acoustic diffraction phase shift, characterized in that: Based on MRT, a numerical method is used to introduce an additional functional phase shift at the sound ray inversion point. The functional phase shift is used to obtain the additional horizontal displacement of the sound ray at the inversion point, so that the sound ray and the simple normal wave in the deep-sea waveguide can be accurately equivalent under low-frequency conditions through the WKB method. remember is the speed of sound at the source, is the sound ray exit grazing angle: (9) The horizontal distance from the upper inversion point to the sound source and receiver, as well as the sound line span, are: (10a) (10b) (10c) in, a , b are the depths of upper and lower reversal points respectively; In a complete deep-sea sound channel, the convergence zone is divided into RR-type convergence zone and RSR-type convergence zone according to the different types of sound rays; according to the position of the convergence zone relative to the sound channel axis, it is divided into upper convergence zone and lower convergence zone; according to the formation mechanism of the convergence zone, it is divided into caustic convergence zone and inversion point convergence zone; according to the horizontal distance from the upper inversion point to the sound source and receiver, as well as the sound ray span, four types of RR-type refracted sound rays are summarized: (11a) (11b) (11c) (11d) In the formula Indicates the number of spans that the sound line travels; If the above four types of sound rays are at a distance Satisfaction: (12) Then the sound rays intersect, and the sound energy is focused here to form a caustic point. Adjacent caustic points in the two-dimensional plane are connected to form caustic lines. According to the characteristics of the four types of sound rays, the contribution of the non-uniform plane wave outside the upper and lower inversion points to the propagation distance, the contribution of the sea surface and seabed reflection phase shift to the propagation distance, and the propagation distance error within a span calculated using the diffraction phase shift are used to correct equations (11a), (11b), (11c), and (11d) to obtain: (13a) (13b) (13c) (13d) It can be seen from equations (13a), (13b), (13c) and (13d) that the introduction of the acoustic diffraction phase shift will reshape the positions of the acoustic ray inversion point and the caustics in the classical ray theory, thereby affecting the positions of the inversion point convergence area and the caustics convergence area. When the frequency gradually increases and the acoustic diffraction phase shift is negligible, equations (13a), (13b), (13c) and (13d) degenerate into equations (11a), (11b), (11c) and (11d).

2. The method according to claim 1, characterized in that The sound velocity distribution is given by the Munk model, which is as follows: (1) In the formula C 1 is the sound velocity of the channel axis, , B =1300 m is the scale depth, m -1 is the sound velocity gradient in an adiabatic environment, =2( z - z 1) / B is the dimensionless distance parameter, z 1 is the channel axis depth.

3. The method according to claim 2, characterized in that The reflection phase shift caused when the inversion point in MRT is close to the waveguide interface and the functional phase shift introduced at the inversion point are collectively referred to as acoustic diffraction phase shift.

4. The method according to claim 3, characterized in that Combined with the modal eigenfunction, additional functional phase shifts are introduced at the upper and lower inversion points of the sound line: (2a) (2b) In formula (2a) and (2b) a , b are the depths of the upper and lower reversal points respectively, and are the derivatives of the speed of sound at the upper and lower inversion points, respectively. is the horizontal wave number, H is the depth of seawater, is the Dirac function: 。 5. The method according to claim 4, characterized in that According to the MRT theory, the reflection phase shift caused by the sound ray reversal point approaching the absolute soft boundary can be written as: (3a) The reflection phase shift caused by the impedance boundary near the seabed is written as: (3b) In formula (3a) and (3b) Ai and Bi Represent Airy function and Biry function respectively, are the Airy function and Biry function quantities. When the inversion point is inside the waveguide: (4a) (4b) When the inversion point exceeds the waveguide boundary, the sound velocity profile needs to be extended. In this case: (4c) (4d) A value of zero indicates that the inversion point is exactly at the waveguide boundary. The larger the absolute value of , the farther the inversion point is from the waveguide boundary; The value of is related to the relative position of the inversion point and the waveguide interface: (5a) (5b)。 6. The method according to claim 5, characterized in that The contributions of the non-uniform plane wave to the propagation distance outside the upper and lower inversion points are defined as: (6a) (6b)。 7. The method according to claim 6, characterized in that The contributions of the sea surface and seabed reflection phase shift to the propagation distance are: (7a) (7b)。 8. The method according to claim 7, characterized in that The propagation distance error within one span calculated using the diffraction phase shift is: (8)。 9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium for storing computer instructions, characterized in that: When the computer instructions are executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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